Manufacture of Ethyl Acrylate From Glycerol (2012)
Transcript of Manufacture of Ethyl Acrylate From Glycerol (2012)
MANUFACTURE OF ETHYL ACRYLATE
FROM GLYCEROL
A Plant Design Presented to
The Faculty of the Chemical Engineering
In Partial Fulfilment of the
Requirements for the Degree of
Bachelor of Science in Chemical Engineering
Prepared by:
Ada, Mark Neil C.
Banta, Mhadel A.
Fonte, Ver Jeneth F.
Judilla, Agnes Dorothy D.
Pagasartonga, Mon Eric P.
October 2012
APPROVAL SHEET
In partial fulfillment of the requirement for the Degree of Bachelor of
Science in Chemical Engineering, this thesis entitled, “Manufacture of Ethyl
Acrylate from Glycerol” proposed and submitted by Mark Neil C. Ada, Mhadel
A. Banta, Ver Jeneth F. Fonte, Agnes Dorothy D. Judilla and Mon Eric P.
Pagasartonga is hereby recommended for approval by
Engr. Jerry G. Olay Panelist
Engr. Merlinda A. Palencia, Ph.D. Panelist
Engr. Renato C. Ong Adviser
Chemical Engineering Department Adamson University
Accepted and approved as partial compliance of the requirement for the
Degree of Bachelor of Science in Chemical Engineering.
Engr. Jerry G. Olay Chairperson
Chemical Engineering Department Adamson University
Letter of Transmittal
September 24, 2012
Engr. Renato C. Ong
Ch. E. Department
Sir:
In compliance to the requirements leading to the Degree of Bachelor of Science in
Chemical Engineering, the endorsement hereby take the pleasure in transmitting
this plant design entitled “Manufacture of Ethyl Acrylate from Glycerol”.
Respectfully yours,
Mark Neil C. Ada Mhadel A. Banta
Ver Jeneth F. Fonte Agnes Dorothy D. Judilla
Mon Eric P. Pagasartonga
ACKNOWLEDGMENT
This Plant Design is a combined effort of the group and several others who,
in one way or another, contributed to the completion of this requirement.
Therefore, it is only fitting that we acknowledge some of these people.
Firstly, this Plant Design could not have been accomplished without the
supervision of Engr. Renato Ong. He consistently encouraged and challenged us to
work with our best endeavors throughout the academic program. For all your
effort and patience, we thank you.
We would also like to give our deepest gratitude to all the authors
mentioned in the bibliography section. The collected knowledge from these
references made this Plant Design possible.
To Engr. Jerry Olay, the chairperson of the Chemical Engineering
Department; and to all the faculty members, including Dr. Merlinda Palencia, Dr.
Erickson Roque, Engr. Sherrie Mae Medez, and Engr. Albert Evangelista, we send
our sincerest appreciation to each of you for all the guidance. Furthermore, to
Engr. Mike Lester Raypan, our personal friend, we deeply appreciate every advice
and all the help we received throughout the research and design process.
We are, of course, forever grateful for the unending love and support of our
families and personal friends. Regardless of how long and tedious the entire
process took, these people were behind us all the way. The grace and heart
everyone has shown us especially through the down times served as our
inspiration to keep pushing forward.
Also, we extend our gratitude to our ChE friends: Engr. Raymond Kenneth
Dionisio, Engr. Kim Marie Barias, Engr. Leanna Mamorno, Khenbert Tecon, and
Edrian Bautista, for their earlier work, and the support they have given since.
Moreover, to our colleagues: Pinky Atregenio, Chessyrr Baylon, Camille
Candelaria, Shienah Ricarte, Rose Ann Suapero, and John Christopher Emalada;
for always being with us in the countless hours of waiting, for all the shared
laughter that kept our sanity, and simply for the company in the past few years,
and hopefully for many more years in the future, from the bottom of our hearts,
thank you.
Lastly, and most important of all, to God, who never failed to pull us when
everyone else cannot push anymore, we thank You with our entirety.
TABLE OF CONTENTS
CHAPTER 1 Product Description
I. Introduction 2
II. Product Profile 6
III. Raw Materials Profile 10
CHAPTER 2 Review of Related Literature
I. Introduction 35
II. Lists of Related Literatures 40
III. Summary of Related Literature
A. Process Description 49
B. Product Literature 72
C. Raw Material Literature 77
D. Design and Equipment Literature 97
CHAPTER 3 Process Description
I. Introduction 130
II. Process Flow Diagram 136
III. Detailed Process Description 137
CHAPTER 4 Plant Capacity Determination
I. Introduction 160
II. Supply and Demand Analysis 164
III. Raw Material Availability 169
IV. Conclusion 170
CHAPTER 5 Mass and Energy Balance
I. Introduction 174
II. Overall Mass & Energy Balance Diagram 176
III. Summary of Basis, Assumptions and Equations 177
IV. Mass Balance per Equipment 188
V. Energy Balance per Equipment 216
CHAPTER 6 Equipment Design
I. Introduction 244
II. Summary of Assumptions and Design Equations 246
III. Equipment Design
1. Dehydration Reactor 279
2. Shell and Tube Heat Exchanger 292
3. Absorption Column 309
4. Esterification Reactor 338
5. Pervaporator 354
CHAPTER 7 Cost Estimation
I. Introduction 375
II. Estimation of Capital Investment 380
III. Estimation of Product Cost 381
CHAPTER 8 Economic Evaluation
I. Introduction 436
II. Analysis and Interpretation
A. Rate of Return on Investment 437
B. Net Present Worth 438
C. Break-even Point Analysis 439
III. Conclusion 440
IV. Detailed Computations 441
APPENDICES 444
Appendix A: References for Product and Raw Material Description
Appendix B: References for Review of Related Literature
Appendix C: References for Process Description
Appendix D: References for Plant Capacity Determination
Appendix E: References for Mass and Energy Balance
Appendix F: References for Equipment Design
Appendix G: References for Cost Estimation
Appendix H: References for Economic Evaluation
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CHAPTER I
PRODUCT
DESCRIPTION
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CHAPTER I
PRODUCT DESCRIPTION
I. INTRODUCTION
Acrylic esters make the main product derived from acrylic acid and
traditionally produced by using propylene as raw material. They account for 55%
of global demand. About half of the crude acrylic acid is processed to purified
(glacial) acrylic acid, which is further processed both on-site (captive use) and by
external downstream users. The other half of crude acrylic acid is transformed into
various acrylate esters at the production sites. Identical to glacial acrylic acid,
these acrylic esters serve as commercial products, which are further processed
both on-site and by external downstream users.
Currently, the trend of using sustainable materials for production is
increasing in popularity due to the changes in global climate and as fossil sources
for hydrocarbons run short. For this reason, the production of fuel from renewable
sources such as biodiesel production is developing fast. In the biodiesel industry,
the biodiesel is produced through the transesterification of natural oils where one
mole of such oil yields three moles of hydrocarbon chains and one mole of
glycerol. The hydrocarbon chains are used as biodiesel fuels and the by-product is
glycerol. Due to the increasing awareness of climate change, these industries are
projected to increase, thus increasing in the glycerol production. However, the
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demand for glycerol is not increasing with the same tendency. This causes the
price for glycerol to decrease, making it an interesting carbon source for
intermediates.
It is known that crude oil price is increasing. In connection to that, the
propylene price increases as well, since it is mainly crude oil based. This can lead
to increasing prices for acrylic acid production. On the other hand, glycerol prices
are decreasing. The reason: Glycerol is not an important intermediate. It is mostly
used in small amounts for cosmetics and for the food industry. Global glycerol
demand is not increasing so fast as the bio-diesel production. The use of glycerol
produced during the bio-diesel process has potential to be an environmentally
carbon source for the production of acrylic acid. Moreover, the economical
valorisation of glycerol makes the bio-diesel production more attractive. Replacing
propylene by glycerol would be an indirect step for improving the sustainability in
environmental care.
The manufacturing process of acrylic acid from glycerol involves first the
dehydration of glycerol to acrolein in phase gas, in the presence of solid catalysts
such as sulfated zirconia has been developed. These catalysts deactivate slowly so
as to permit long reaction cycles and low reactor volumes. The dehydration of
glycerol to acrolein takes place in the gas phase and can be expressed as:
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That means, for each mole of glycerol, one mol of acrolein and two moles
of water (steam) are formed. In the case of the dehydration of glycerol, the
reaction is carried out in the presence of a solvent. The reaction takes place in a
catalyst fix bed, heated up by an oven with a heat homogenization system to
assure the heat homogenization. The gaseous products coming out from the reactor
are condensed in a glass reflux heat exchanger. The liquid is collected in a
continuously glass cooled double-coated flask. A sample can be taken for the
analysis, or the condensate can be transferred to the product flask.
The next process is the oxidation of acrolein which produces the product,
acrylic acid. This takes place in another catalyst fixed bed. The catalyst used is
vanadium-molybdenum oxide.
Technical Grade Acrylic Acid which usually has a purity of about 95%.
Technical acrylic acid is suitable for the production of commodity acrylate esters.
Acrylic Acid and its esters (which include methyl, ethyl, n-butyl, and 2-ethylhexyl
acrylate) are among the most versatile monomers for providing performance
properties to a wide variety of polymers. Major markets for the commodity esters
include surface coating, adhesive and sealants, textiles, plastic additives, and paper
treatment.
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Acrylic esters may also be used in solutions and emulsions; the ethyl ester
is used in water-based paints and binders in non-woven fabrics; methyl ester as the
copolymer component of acrylic fibres; the butyl ester in the water-based paints
and adhesives; and the 2-ethylhexyl ester, used like the butyl ester as well as for
stick-on labels and sealants. Co-polymers and blends of methyl methacrylate,
butyl acrylate and ethyl hexyl acrylate are used in acrylic gloss paints where the
acrylates typically represent between 20 and 30 percent (dry basis) of the
formulation.
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II. PRODUCT PROFILE
Acrylic acid and its esters have served, for more than 30 years, as an
essential building block in the production of some of our most commonly used
industrial and consumer products. One of its esters, ethyl acrylate, is used in the
production of polymers including resins, plastics, rubber, and denture material. It
is a clear liquid with an acrid penetrating odor. The human nose is capable of
detecting this odor at a thousand times lower concentration than is considered
harmful if continuously exposed for some period of time. Acrylic acid and its
esters readily combine with themselves or other monomers which are used in the
manufacture of various plastics, coatings, adhesives, elastomers, as well as floor
polishes, and paints.
A. PRODUCT IDENTIFICATION
Product Name Ethyl Acrylate
IUPAC Ethyl propenoate
Molecular Formula C5H8O2
Molecular Weight 100.12 g/mole
Specific gravity 0.922 (20°C)
Melting point -72°C
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Boiling point 99.5 °C
Viscosity 0.55 Pa⋅s (25 °C)
Surface tension 25.2 mN/m (20°C)
Vapor pressure 29.3 mmHg (20°C)
Vapor density 3.45
Solubility in water 1.5 g/100g (25 °C)
B. PRODUCT COMPOSITION
SUBSTANCE CONCENTRATION BY WEIGHT
Ethyl acrylate 98%
Acrylic acid 1%
Ethanol 1%
C. HAZARD IDENTIFICATION
Physical State and Appearance Liquid
Color Colorless to Light Yellow
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Odor Penetrating Lachrymator (Strong)
Incompatibility with various
substances
Product may react violently with water to
emit toxic gases or it may become self-
reactive under conditions of shock or
increase in temperature or pressure.
Corrosivity Non-corrosive in presence of glass.
Stability Stable
D. PRODUCT TRANSPORT, HANDLING AND STORAGE
Handling
Keep locked up Keep container dry. Keep
away from heat. Keep away from sources
of ignition. Keep away from direct sunlight
or strong incandescent light. Ground all
equipment containing material. Do not
ingest. Do not breathe
gas/fumes/vapour/spray. Never add water
to this product Avoid shock and friction. In
case of insufficient ventilation, wear
suitable respiratory equipment. If ingested,
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seek medical advice immediately and show
the container or the label. Avoid contact
with skin and eyes.
Storage
Flammable materials should be stored in a
separate safety storage cabinet or room.
Keep away from heat. Keep away from
sources of ignition. Keep container tightly
closed. Keep in a cool, well-ventilated
place. Ground all equipment containing
material. A refrigerated room would be
preferable for materials with a flash point
lower than 37.8°C (100°F).
E. PRODUCT SAFETY
(Refer to Appendix, Material Safety and Data Sheet)
F. APPLICATION
Use as main raw material in production of acrylic latex paint.
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III. RAW MATERIALS PROFILE
• GLYCEROL
Glycerol is the common name of propane-triol. It is a sweet tasting, highly
viscous colorless and odorless liquid with no known toxic properties. Glycerol has
many direct utilization fields, such as cosmetics, lubricants or explosives, and
other applications. Glycerol is a side-product of bio-diesel production. Natural oils
are triglycerides. The transesterification of one mole of such an oil yields three
moles of hydrocarbon chains and one mole of glycerol. The hydrocarbon chains
are used as bio-diesel fuels. Due to the developments in the bio-diesel industry, the
glycerol production is also increasing. Since the demand for glycerol is not
increasing with the same tendency, the glycerol price is decreasing, which makes
it an interesting carbon source for intermediates.
A. RAW MATERIAL IDENTIFICATION
Raw Material Name Glycerol
Synonyms
1, 2, 3-propanetriol
Glycerine
Glycol alcohol
Chemical Family Alcohol
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Molecular Formula C3H5(OH)3
Structural Formula
Molecular Weight 92.10 g/mol
Density 1.261 g/cm³
Specific gravity 1.261
Melting point 17.8 °C (64.2°F)
Boiling point 290 °C (554°F)
Solubility Partially soluble in water
Appearance Clear oily liquid
Color colorless
Odor odorless
Surface tension 64.00 mN/m at 20 °C
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B. RAW MATERIAL COMPOSITION
SUBSTANCE CONCENTRATION BY WEIGHT
Glycerol <60%
Water >40%
C. HAZARD IDENTIFICATION
Physical State Liquid (viscous)
Stability stable
Flammability Slight
Incompatibility Reactive with oxidizing agents
D. STABILITY AND REACTIVITY
Stability Stable under ordinary conditions of use and
storage.
Hazardous Decomposition
Products
Toxic gases and vapor may be released if
involved in a fire. Glycerin decomposes
upon heating above 290°C, forming
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corrosive gas (acrolein).
Hazardous Polymerization Will not occur.
Incompatibilities
Strong oxidizers. Can react violently with
acetic anhydride, calcium oxychloride,
chromium oxides and alkali metal
hydrides.
Conditions to Avoid Heat, flames, ignition sources and
incompatibles.
E. HANDLING AND STORAGE
Handling
Crude glycerol is shipped to
refiner/manufacturing plants in standard
tank cars or tank wagons.
Storage
Glycerol solidifies at lower temperatures,
and should be kept warm during
transportation and storing. Large storage
tanks should contain a heated loop from a
boiler or other heat source. Also, the boiler
room should be heated to prevent the
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glycerol from gelling in the fuel lines, fuel
filters, and the boiler itself.
F. RAW MATERIAL SAFETY
(Refer to Appendix, Material Safety and Data Sheet)
G. APPLICATION
Glycerol is used as the major raw material for the manufacture of acrylic
acid and thus converting the acrylic acid to ethyl acrylate.
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• AIR
Air is mainly composed of nitrogen, oxygen, and argon, which together
constitute the major gases of the atmosphere. The remaining gases are often
referred to as trace gases. Dry air contains roughly (by volume) 78.09% nitrogen,
20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other
gases. Air also contains a variable amount of water vapor, on average around 1%.
While air content and atmospheric pressure varies at different layers, air suitable
for the survival of terrestrial plants and terrestrial animals is currently only known
to be found in Earth's troposphere and artificial atmospheres.
A. RAW MATERIAL IDENTIFICATION
Raw Material Name Air
Appearance and Odor Colorless and odorless gas
Vapor Density @ 70°F 1.2 kg/m3 (0.0749 lb/ft3)
Specific Gravity Not applicable
Molecular Weight 28.97
Solubility in Water (v/v) 0.0292
Vapor Pressure Gas, ambient
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Freezing Point -216.2°C (-357.2°F)
Boiling Point (1 atm) -194.3°C (-317.8°F)
Specific Volume (ft3/lb): 13.8 (for Nitrogen)
B. RAW MATERIAL COMPOSITION
COMPONENT COMPOSITION BY MOLE
Nitrogen 79%
Oxygen 21%
C. STABILITY AND REACTIVITY
Stability
Normally stable in gaseous state. Air which
contains excess oxygen may present the
same hazards as liquid oxygen and could
react violently with organic materials such
as oil and grease.
Materials with which Substance
is Incompatible
Fuels may form explosive mixtures with
air.
Hazardous Polymerization Will not occur
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Conditions to Avoid
Contact with incompatible materials.
Avoid exposing cylinders to extremely
high temperatures, which could cause the
cylinders to rupture.
D. HANDLING AND STORAGE
Handling
Protect cylinders against physical damage.
Store in cool, dry, well-ventilated, fireproof
area, away from flammable or combustible
materials and corrosive atmospheres. Store
away from heat and ignition sources and
out of direct sunlight. Do not allow area
where cylinders are stored to exceed 52°C.
Storage
Use only DOT or ASME code containers.
Store containers away from heavily
trafficked areas and emergency exits.
Cylinders should be stored in dry, well-
ventilated areas away from sources of heat.
Cylinders should be stored upright and be
firmly secured to prevent falling or being
knocked over.
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E. RAW MATERIAL SAFETY
(Refer to Appendix, Material Safety and Data Sheet)
F. APPLICATION
Air serves as a reactant in the process of converting acrolein to acrylic acid
(oxidation process).
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• ETHYL ALCOHOL
Ethyl alcohol is classified as a primary alcohol, meaning that the carbon its
hydroxyl group attaches to has at least two hydrogen atoms attached to it as well.
Many ethanol reactions occur at its hydroxyl group. Ethanol is often abbreviated
as EtOH, using the common organic chemistry notation of representing the ethyl
group (C2H5) with OH. Ethanol has widespread use as a solvent of substances
intended for human contact or consumption, including scents, flavorings,
colorings, and medicines. In chemistry, it is both an essential solvent and a
feedstock for the synthesis of other products.
A. RAW MATERIAL IDENTIFICATION
Raw Material Name Ethanol
Appearance Colorless clear liquid
Odor Mild, pleasant
Specific Gravity 0.790
Molecular Formula C2H5OH
Molecular Weight 46.0414
Solubility Miscible
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Vapor Pressure 59.3 mmHg @ 20°C
Vapor Density 1.59
Melting Point -114.1°C
Boiling Point 78°C
B. RAW MATERIAL COMPOSITION
COMPONENT CONCENTRATION BY WEIGHT
Ethanol 100%
C. STABILITY AND REACTIVITY
Stability Stable
Conditions of Instability Excess heat, incompatible materials,
water/moisture
Materials with which Substance
is Incompatible
Strong oxidizing agents, acids, alkali
metals, ammonia, hydrazine, peroxides,
acid anhydrides, silver oxide, acid
chlorides.
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Hazardous Decomposition
Products
Carbon monoxide, carbon dioxide,
irritating and toxic fumes and gases.
Polymerization Will not occur
D. HANDLING AND STORAGE
Handling
Wash thoroughly after handling. Use only
in a well-ventilated area. Ground and bond
containers when transferring material. Use
spark-proof tools and explosion proof
equipment. Avoid contact with eyes, skin
and clothing. Keep container tightly closed.
Avoid contact with heat, sparks and flame.
Avoid ingestion and inhalation. Do not
pressurize, cut, weld, braze, solder, drill,
grind, or expose empty containers to heat,
sparks or open flames.
Storage
Keep away from heat, sparks and flame.
Keep away from the source of ignition.
Store in a tightly closed container. Keep
from oxidizing materials. Store in a cool,
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well-ventilated area away from
incompatible substances.
E. RAW MATERIAL SAFETY
(Refer to Appendix, Material Safety and Data Sheet) F. APPLICATION
Ethanol is used as a reactant in the esterification process of acrylic acid
yielding to ethyl acrylate and water.
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• TUNGSTATED ZIRCONIA
Tungstated Zirconia is a heterogeneous catalyst which is composed of
Zirconium Oxide (Zirconia) and Tungsten Oxide. Zirconia serves as the carrier of
the Tungsten Oxide which is the more active component in the system. This
catalyst will be used in the dehydration process of glycerol.
A. RAW MATERIAL IDENTIFICATION
Zirconium Oxide
Raw Material Name Zirconium Oxide
Appearance Powdered solid
Odor Odorless
Color White
Taste Tasteless
Molecular Weight 123.22
Specific Gravity 5.85
Solubility
Insoluble in cold water, hot water. Slightly
soluble in Hydrochloric acid, Nitric Acid.
Slowly soluble in HF.
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Melting Point 2680°C
Boiling Point 4300°C
Tungsten Oxide
Raw Material Name Tungsten Oxide
Appearance Powdered solid
Odor Odorless
Color yellow to yellow-green
Molecular Weight 231.85
Specific Gravity 7.16
Solubility Insoluble in cold water
Melting Point 1473°C
Boiling Point 4300°C
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B. RAW MATERIAL COMPOSITION
COMPONENT CONCENTRATION BY WEIGHT
Zirconium Oxide
(CAS 1314-23-4) ≥90%
Tungsten Oxide
(CAS 1314-35-8) ≤10%
C. HANDLING AND STORAGE
Raw Material Name Zirconium Oxide
Handling Do not breathe dust.
Storage
Keep away from incompatibles such as
oxidizing agents. Keep container tightly
closed. Keep container in a cool, well-
ventilated area.
Raw Material Name Tungsten Oxide
Handling Keep away from heat. Keep away from
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sources of ignition. Empty containers;
evaporate the residue under a fume hood.
Do not ingest. Do not breathe dust. Avoid
contact with eyes. Wear suitable protective
clothing. In case of insufficient ventilation,
wear suitable respiratory equipment. If
ingested, seek medical advice immediately.
Storage
Keep container dry. Keep in a cool place.
Ground all equipment containing material.
Keep container tightly closed. Keep in a
cool, well-ventilated place.
D. RAW MATERIAL SAFETY
(Refer to Appendix, Material Safety and Data Sheet)
E. APPLICATION
Tungstated Zirconia serves as a catalyst in the process of dehydration of
glycerol to acrolein.
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• VANADIUM-MOLYBDENUM OXIDE
Vanadium-Molybdenum Oxide Catalyst is a type of heterogeneous catalyst
which is composed of Vanadium (IV) Oxide and Molybdenum Trioxide. This
catalyst will be used for the oxidation process of acrylic acid.
A. RAW MATERIAL IDENTIFICATION
Vanadium (IV) Oxide
Raw Material Name Vanadium (IV) Oxide
Appearance crystalline powder
Odor odorless
Color blue
Molecular Weight 82.94
Specific Gravity 4.339
Solubility Insoluble in water
Melting Point 1967 oC
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Molybdenum Trioxide
Raw Material Name Molybdenum Trioxide
Appearance yellow solid
Odor odorless
Molecular Weight 143.94
Specific Gravity 4.69
Solubility in water 2.055 g/100 mL (70 °C)
Melting Point 795 °C
Boiling Point 1155 °C
B. RAW MATERIAL COMPOSITION
COMPONENT CONCENTRATION BY WEIGHT
Vanadium(IV) Oxide
(CAS 12036-21-4)
≤16%
Molybdenum Trioxide
(CAS 1313-27-5)
≥84%
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C. HANDLING AND STORAGE
Raw Material Name Vanadium(IV) Oxide
Handling
Open and handle container with care.
Wash thoroughly after use. Store away
from halogens. Do not get in eyes, on skin
or clothing. Do not breathe dust, vapor,
mist, gas.
Storage Keep container tightly closed. Store in a
cool, dry, well-ventilated area.
Raw Material Name Molybdenum Trioxide
Handling
Protect from physical damage. Containers
of this material may be hazardous when
empty since they retain product residues
(dust, solids); observe all warnings and
precautions listed for the product.
Storage Keep in a tightly closed container.
Store in a cool, dry, ventilated area away
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from sources of heat, moisture and
incompatibilities.
D. RAW MATERIAL SAFETY
(Refer to Appendix, Material Safety and Data Sheet) E. APPLICATION
Vanadium-Molybdenum Oxide Catalyst serves as a catalyst in the process
of oxidation of acrolein to acrylic acid.
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• SULFURIC ACID
Sulfuric acid is a highly corrosive strong mineral acid. It is a very important
commodity chemical. The historical name for this acid is oil of vitriol. It is a
viscous liquid and is soluble in water at all concentrations. The corrosiveness of it
is mainly due to its strong acidic nature, strong dehydrating property and if
concentrated strong oxidizing property. Principal uses include lead-acid batteries
for cars and other vehicles, mineral processing, fertilizer manufacturing, oil
refining, wastewater processing and chemical synthesis.
A. RAW MATERIAL IDENTIFICATION
Raw Material Name Sulfuric acid
Appearance Colorless to slightly yellow liquid
Odor with pungent odor
Specific Gravity 1.834 (20 °C)
Molecular Formula H2SO4
Molecular Weight 98.08
Solubility Miscible in water
Viscosity 26.7 cP (20°C)
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Melting Point 10.31°C
Boiling Point 337°C
B. RAW MATERIAL COMPOSITION
COMPONENT CONCENTRATION
Sulfuric acid 18 M (98 %wt)
C. STABILITY AND REACTIVITY
Stability Stable
Materials with which Substance
is Incompatible
Oxidizers, Acids, Metals, Bases, Alkalis,
Reducing agents, Water, Organics, Metal
carbides. Product is water reactive.
Hazardous Decomposition
Products SOx, Hydrogen Gas
Polymerization Will not occur
33
D. HANDLING AND STORAGE
Handling Keep container tightly closed in a cool,
well-ventilated place.
Storage
Store in a secure area suitable for toxic
material.
Keep locked up and out of the reach of
children. Never add water to this product.
E. RAW MATERIAL SAFETY
(Refer to Appendix, Material Safety and Data Sheet)
F. APPLICATION
Sulphuric acid is used as a catalyst in the process of esterification of acrylic
acid to the product ethyl acrylate.
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CHAPTER II
REVIEW OF
RELATED LITERATURE
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CHAPTER II
REVIEW OF RELATED LITERATURE
I. INTRODUCTION
Biodiesel is made through a catalyzed chemical reaction
(transesterification) between oils or fats and an alcohol (usually methanol). It has
showed its importance as renewable and clean source of fuel for diesel engines.
Common feedstocks are pure vegetable oil (e.g., soybean, canola, sunflower),
rendered animal fats, or waste vegetable oils. Strong bases such as sodium
hydroxide (NaOH) or potassium hydroxide (KOH) are commonly used as
catalysts.
As the biodiesel industry is rapidly expanding, a glut of crude glycerol is
being created. Crude glycerol is the major by-product of the biodiesel industry. In
general, for every 100 pounds of biodiesel produced, approximately 10 pounds of
crude glycerol are created. Because this glycerol is expensive to purify for use in
food, pharmaceutical, or cosmetics industries, biodiesel producers must seek
alternative methods for its disposal.
Glycerol itself can not be burnt as a fuel, because at high temperatures it
polymerizes and partially oxidizes to toxic acrolein. Besides it is also very difficult
to use the glycerol coming from biodiesel production for its traditional uses in
pharmacy and cosmetic since it does not have the required purity.
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As a growing concern in the abundance of waste glycerol and the lack of
areas to dispose this large waste stream, combustion of glycerol may be one of the
simplest solutions. Clean combustion of glycerol is not possible because of its
properties. In particular, burning of it will produce acrolein which is the thermal
decomposition product of glycerol and is toxic at very low concentrations.
With the increasing expansion of biomass as raw material in general, and
biodiesel production in particular, glycerol is expected to become a major
chemical platform for future biorefineries since it has emerged as an important
organic building block. However, developing selective glycerol based catalytic
processes is a major challenge. Thus, a high number of patents and research papers
are being published nowadays.
The dehydration of glycerol into acrolein has been known since the
nineteenth century. Acrolein or acrylic aldehyde is used as intermediate for the
production of many useful compounds as acrylic acid, acrylic acid esters, super
absorber polymers and detergents. A sustainable and cost efficient dehydration of
glycerol to acrolein could offer an alternative for the current commercial catalytic
petrochemical process based on the reaction of propylene over a Bi/Mo-mixed
oxide catalyst. In addition, direct synthesis of acrylonitrile and acrylic acid from
glycerol is an attractive approach since both compounds are useful chemicals as
raw materials for various synthetic resins, paints, fibbers etc.
37
Gas-phase catalytic oxidation of acrolein to acrylic acid has been given
attention since late 1960s being concerned with the development of the two-step
process fro production of acrylic acid from propene via acrolein as an
intermediate. Acrylic acid is a versatile chemical that can be esterified, aminated
or otherwise modified and polymerised to complex molecular arrangements to suit
requirements. This characteristic enables a broad range of reactions for providing
performance characteristics to a range of polymers.
A high purity form (often referred to as glacial acrylic acid) is produced by
a second distillation or crystallisation that reduces aldehyde impurities (especially
furfural) which inhibit polymerisation. Different grades of glacial acrylic acid are
available with flocculants requiring higher purity levels than dispersants and some
other applications while a technical grade of acrylic acid may be produced by a
simple distillation to produce a grade of acid suitable for the manufacture of
acrylic esters, but unsuitable for polymerisation.
The esters are produced by reacting acrylic acid with alcohols especially
ethanol, methanol and butanol that may be saponified, converted to other esters or
amides by aminolysis. Acrylates are derivatives of acrylic acid (such as methyl
and ethyl acrylate) whose properties have been sufficiently modified to enable of
acrylic acid to be used in different media as emulsion and solution polymers. As
emulsions, these products may be used as coatings, finishes and binders leading to
applications in paints, adhesives, and polishes with solutions used for industrial
38
coatings. Two-third of the world's production of acrylic acid is used to produce
acrylic esters (acrylates) primarily for use in emulsions and solution polymers for
latex-based paints, coatings, adhesives and textiles.
Ethyl and methyl acrylates are manufactured on a continuous basis by
passing acrylic acid and a small excess of the alcohol in a reactor bed at elevated
temperature extracted at a yield of about 90 to 95 percent. Acrylic esters may be
polymerised, catalysed by heat and oxidising agents in solution or emulsion
methods to form long-chain thermoplastic resins. Broadly, acrylic ester polymers
are colourless, insoluble in aliphatic hydrocarbons and resistant to alkali, mineral
oils and water so that with good resistance to degradation, adhesion and electrical
properties, they are widely used.
Researches show varieties of glycerol transformations and processing that
include the manufacture of ethyl acrylate. There are three major processes involve
in this conversion, the dehydration of glycerol into acrolein, oxidation to form
acrylic acid and esterification to produce ethyl acrylate. Synthesis of acrylic acid
from glycerol represents an economic advantage since the latter does not
contribute to global warming.
Acrylates are used in a broad range of applications directly as a resin, or as
solution or emulsion. The following provides an indication of typical applications
with the market share expressed as a percentage of all acrylic acid applications as
acrylic acid. Surface coatings, such as paints, represent the largest application for
39
acrylic esters at about 19 per cent of the market. Demand, that was motivated by
the convenience of water-based paints especially the superior acrylic-based
emulsions, is now being driven by regulations and interests to reduce atmospheric
release of volatile organic compounds (VOCs) used as solvents in traditional
(alkyd-based) surface coatings. This sector is growing at 3 to 5 per cent per year
with faster growth for newer more sophisticated applications.
Extensive research is applied to acrylic chemistry and with a very broad
range of alternative processes, this activity has become specialised with patents
and proprietary knowledge. There are now more manufacturers of specialty acrylic
esters (that do not themselves manufacture acrylic acid) than there are
manufacturers of the acid. The esters are generally produced near major traditional
markets and suppliers of acrylic acid.
40
II. LISTS OF RELATED LITERATURES
BOOKS
• Gavin T. et al. (2008). Chemical Engineering Design Principles, Practice and
Economics of Plant and Process Design. 2nd Ed. U.S.: Elsevier, Inc.
• Geankoplis, Christie J. (1993). Transport Processes and Unit Operations. 3rd
Ed. Prentice-Hall International, Inc.
• McCabe. W. et al. (2001). Unit Operations of Chemical Engineering. 6th Ed.
New York: McGraw-Hill
• Octave L. et al. (1999). Chemical Reaction Engineering. 3rd Ed. John Wiley &
Son, Inc.
• Perry, R. and Green, D. (2008). Perry’s Chemical Engineers’ Handbook. 8th
Ed. New York: McGraw-Hill
• Shah, R. et al. (2003). Fundamentals of Heat Exchanger Design. John Wiley &
Sons.
• Treybal, Robert E. (1981). Mass-Transfer Operations. 3rd Ed. New York:
McGraw-Hill
• Ullman’s (2004). Processes and Process Engineering. Wiley-VCH, Vol. 3.
ENCYCLOPEDIA
• Kirk-Othmer (1999). Concise Encylopedia of Chemical Technology. 4th Ed.
New York: John Wiley & Sons, Inc.
41
INTERNET
• Acrylic Acid. Retrieved from www.chemsystems.com
• Acrylic Acid manufacture in Western Australia
Retrieved from http://www.chemlink.com.au/acryful.htm
• Acrylic Acid Production: Separation and Purification. Lin, Stephany et al.
http://www.owlnet.rice.edu/~ceng403/gr2499/aagrp4.html
• Acrylic Acid Production via the Catalytic Partial Oxidation of Propylene:
Separation Design
http://www.owlnet.rice.edu/~ceng403/gr21099/acrylicacid2.htm
• Compilation of Henry’s Law Constant for Inorganic and Organic Species of
Potential Importance in Environmental Chemistry
http://www.mpch-mainz.mpg.de/~sander/res/henry.html
• Ethanol
http://www.chemeurope.com/en/encyclopedia/Ethanol.html
• Gases of the Air
Retrieved from http://scifun.chem.wisc.edu/chemweek/pdf/airgas.pdf
• Method for Production of Acrylic Acid
http://www.patentstorm.us/patents/7332624/fulltext.html
• Pervaporation An Overview
http://www.cheresources.com/content/articles/separation-
technology/pervaporation-an-overiew
42
• Production of Acrylic Acid
http://sbioinformatics.com/design_thesis/Acrylic_Acid/Acrylic-2520Acid.htm
• Sulfuric Acid
http://www.chemeurope.com/en/encyclopedia/Sulfuric_acid.html
• The Mechanism for the Esterification Reactor
http://www.chemguide.co.uk/physical/catalysis/esterify.html
• Turbine & High Efficiency Axial Flow Agitators
http://www.feldmeier.com/cutsheets/turbine_agitator.pdf
JOURNALS
• Alvarez, M et al. (2007). Evaluation of Liquid-Liquid Extraction Process for
Separating Acrylic Acid Produced from Renewable Sugars.
• Chai, Song-Hai et al. (2007). Sustainable Production of Acrolein: Gas-phase
Dehydration of Glycerol over Nb2O5 Catalyst. Journal of Catalysis 250: 342-
349.
• Chengwang, Z. Acrylic Acid: Raw material cost pushed prices of acrylic acid
and esters.
• Cortes-Jacome, M.A. et al. (2006). Generation of WO3-ZrO2 Catalysts from
Solid Solutions of Tungsten in Zirconia. Journal of Solid State Chemistry 179:
2663-2673.
43
• Deleplanque, J. et al. (2010). Production of Acrolein and Acrylic Acid through
Dehydration and Oxydehydration of Glycerol with Mixed Oxide Catalysts.
Catalysis Today 157: 351-358.
• El-Zanati, E. et al. (2006). Modeling and Simulation of Butanol Separation
from Aqueous Solutions Using Pervaporation. Journal of Membrane Science
280 (2006) 278–283.
• Fan, X. et al. (2010). Glycerol (Byproduct of Biodiesel Production) as a Source
for Fuels and Chemicals - Mini Review. The Open Fuels & Energy Science
Journal, Vol. 3, 17-22.
• Guerrero-Perez, M.O. et al. (2009). Recent Inventions in Glycerol
Transformations and Processing. Recent Patents on Chemical Engineering,
Vol. 2, No. 1.
• Kaszonyi, A. et al. (2009). Bioglycerol: A New Platform Chemical. 44th
International Petroleum Conference, Bratislava, Slovak Republic, September
21-22, 2009.
• Kim, Y.T. et al. (2010). Gas-phase Dehydration of Glycerol over ZSM-5
Catalysts. Microporous and Mesoporous Materials 131: 28-36.
• Kraai, G. et al. (2008). Kinetic Studies on the Rhizomucor miehei lipase
catalyzed Esterification Reaction of Oleic acid with 1-butanol in a Biphasic
System. Biochemical Engineering Journal 41 (2008) 87–94.
44
• Kujawski, W. (2000). Application of Pervaporation and Vapor Permeation in
Environmental Protection. Polish Journal of Environmental Studies Vol. 9, No.
1 (2000), 13-26
• Lipnizki, F. et al (1999). Simulation and Process Design of Pervaporation
Plate-and-Frame Modules to Recover Organic Compounds from Waste Water.
Institution of Chemical Engineers Trans IChemE, Vol 77, Part A, May 1999.
• Tao, L.Z. et al. (2010). Sustainable Production of Acrolein: Acidic Binary
Metal Oxide Catalysts for Gas-phase Dehydration of Glycerol. Catalysis
Today 158: 310-316.
• Tichy, Josef (1997). Oxidation of Acrolein to Acrylic Acid over Vanadium-
Molybdenum Oxide Catalysts. Applied Catalysts A: General 157: 363-385.
• Ulgen, A. and Hoelderich, W. (2009). Conversion of Glycerol to Acrolein in
the Presence of WO3/ZrO2 Catalysts. CatalLett 131:122-128
• Wang, F. et al. (2009). Catalytic Dehydration of Glycerol over Vanadium
Phosphate Oxides in the Presence of Molecular Oxygen. Journal of Catalysis
268, 260-267.
PATENTS
• AlArifi, S. et al. (2011). Synthesis of Acrylic or Methacrylic Acid/Acrylate or
Methacrylate Ester Polymers Using Pervaporation.
European Patent Number 2325214
United States Patent Number 2011/0124829
45
• Bunning, D. et al. (1991). Process for Producing Acrylic Ester.
United States Patent Number 4999452
• Diefenbacher, A. et al. (2009). Process for Preparing Acrylic Acid.
United States Patent Number 7566804
• Dubois, Jean-Luc (2010). Method for Preparing Acrylic Acid from Glycerol.
United States Patent Number 2010/0168471
• Dubois, Jean-Luc (2010). Process for Manufacturing Acrolein from Glycerol.
United States Patent Number 2010/0204502
• Dubois, J.L. et al. (2008). Method for Producing Acrylic Acid from Glycerol.
United States Patent Number 2008/0183013
• Dubois, J.L. et al. (2008). Process for Dehydrating Glycerol to Acrolein.
United States Patent Number 2008/0146852
United States Patent Number 2008/0214880
United States Patent Number 7396962
• Elder, J. et al. (2003). Process for Preparing and Purifying Acrylic Acid From
Propelyne Having Improved Capacity.
US Patent Number 6639106
• Figueras, F. et al. (2006). Tungsten Catalysts.
United States Patent Number 2006 /0091045
• Hammon, U. et al. (1993). Catalytic Gas-phase Oxidation of Acrolein to
Acrylic Acid.
46
United States Patent Number 5264625
• Hecquet, G. et al. (2000). Process for the Manufacture of Acrylic Acid from
Acrolein by a Redox Reaction and Use of a Solid Mixed Oxide Composition as
Redox System in the said reaction.
United States Patent Number 6025523
• Hego, M. et al. (1998). Process and Apparatus for Purification of a Gas
Stream Containing Acrolein.
United States Patent Number 5770021
• Hershberger, B.L., et al. (2005). Method of Producing Ethyl Acrylate.
United States Patent Number 2005/0107629
• Ishidoya, M. et al. (1992). Resin Composition for Use as Paint.
United States Patent Number 5091492
• Ishii, Y. et al. (2006). Method for Purification of Acrylic Acid.
Unites States Patent Number 7048834
• Jones, L. et al. (1994). Process for the Production of Plasticizers and
Polyolesters.
United States Patent Number 5324853
• Kang, S. et al. (2009). Method for Producing (Meth) Acrylic Acid.
United States Patent Number 7632968
• Kang, S. et al. (2008). Method for Producing (Meth) Acrylic Acid.
United States Patent Number 7319169
47
• Krabetz, R. et al. (1986). Production of Acrylic Acid by Oxidation of Acrolein.
United States Patent Number 4620035
• Kautter, C.T. et al. (1969). Esterification of Acrylic Acid.
United States Patent Number 3458561
• Neher, A. et al. (1995). Process for the Production of Acrolein.
United States Patent Number 005387720
• Rezkallah, Areski (2008). Method for Purification of Glycerol.
United States Patent Number 2008/0249338
• Ruppel, W. et al. (1998). Catalytic Gas-Phase Oxidation of Acrolein to Acrylic
Acid.
United States Patent Number 5739391
• Sato, T. et al. (1982). Process for Preparing and Recovering Acrylic Acid.
United States Patent Number 4317926
• Shidhar, Srinivasan (1995). Process for the Removal of Water from Acrylic
Acid.
United States Patent Number 5463121
• Soohoo, T. et al. (2007). Membrane-assisted Fluid Separation Apparatus and
Method.
United States Patent Number 7758754
• Tanimoto, M. et al. (2011). Process for Producing Acrolein and/or Acrylic
Acid.
48
United States Patent Number 2011/0015432
• Tanimoto, M. et al. (2010). Process for Producing Acrolein and Acrylic Acid.
United States Patent Number 2010/0249455
• Yukawa, Yoshiyuki (2009). Water-Based Paint Compositions.
United States Patent Number 2009/0099298
OTHER REFERENCES
• Alzate, Javier Fontalvo (2006). Design and Performance of Two-Phase Flow
Pervaporation and Hybrid Distillation Processes.
• Arda, Ulgen (2009). Conversion of Glycerol to the Valuable Intermediates of
Acrolein and Allyl Alcohol in the Presence of Heterogeneous Catalysts.
• Gott, Paige (2009). Variation in the Chemical Composition of Crude Glycerin.
• Prieto, Sergio Sabater (2007). Optimization of the Dehydration of Glycerol to
Acrolein and a Scale up in a Pilot Plant.
• Pyle, Denver J. (2008). Use of Biodiesel-Derived Crude Glycerol for the
Production of Omega-3 Polyunsaturated Fatty Acids by the Microalga
Schizochytriumlimacinum.
• US outlook for Acrylic Acid & Derivatives with forecast to 2006-2011 (THE
FREEDONIA GROUP, INC.)
• Xu, Weihua (2001). Design and Development of a Pervaporation Membrane
Separation Module.
49
III. SUMMARY OF RELATED LITERATURE
A. PROCESS DESCRIPTION
Dehydration of Glycerol to Acrolein
Conversion of glycerol to acrolein has been known since the nineteenth
century and there are several recent patents describing this process, but the
majority of them describe as the dehydration of glycerol to form acrolein. Acrolein
is a highly toxic material with extreme lachrymatory properties. At room
temperature acrolein is liquid with volatility and flammability somewhat similar to
acetone. It is usually synthesized on the site of production to minimize the storage
and transportation because of the flammability, reactivity and toxicity of acrolein.
According to Guerrero-Perez et al. in “Recent Inventions in Glycerol
Transformations and Processing” from Recent Patents on Chemical Engineering,
2009, Vol. 2, No.1, dehydration of glycerol to acrolein is normally performed over
acid catalysts. Glycerol can be supplied to the reactor in liquid or in gas phase but
it was found that acrolein yields were lower in liquid phase than in gas phase. As
by Y.T. Kim et al. in their work entitled “Gas-phase dehydration of glycerol over
ZSM-5 catalysts” from Microporous and Mesoporous Materials 131(2010), they
include to the study the information that high glycerol conversion and selectivity
for acrolein can be modulated in the gas-phase reaction. In the invention of Dubois
of US Patent 2010/0168471 with title “Method for Preparing Acrylic Acid from
Glycerol”, he stated that “the use of an aqueous solution of glycerol has a
50
drawback of producing a stream containing not only the acrolein produced and
the by-products, but also a large quantity of water, originating partly from the
glycerol solution, and partly from the water produced by the dehydration
reactor.”
There are different types of catalysts that can be incorporated in the
dehydration process. The best catalysts that would yield acrolein over 70%,
discussed by A. Kaszonyi et al. in the “Bioglycerol: A new Platform Chemical”
from the paper released by the 44th International Petroleum Conference (Slovak
Republic, September 21-22, 2009), are the most acidic catalysts with Hammett
acidity constants H0 between -10 and -16. The catalysts at lower acidity will
relatively easily deactivate and acrolein yield will be below 60%. Supported by
Dubios et al. from US Patent 2008/0214880 with invention title “Process for
Dehydrating Glycerol to Acrolein”, they claimed that the process is accompanied
by “a strongly acidic solid catalyst with Hammett acidity H0 of between -9 and -
18 and preferably between -10 and -16.”
A. Ulgen and W. Hoelderich describe the “Conversion of Glycerol to
Acrolein in the Presence of WO3/ZrO2 Catalysts” (CatalLett, 2009, 131:122-128).
They reported that with their collaboration with Arkema, they found out that
WO3/ZrO2 catalysts yields 73-80% of acrolein. Among the various solid-acid
catalysts studied by S. Prieto in his dissertation entitled “Optimization of the
Dehydration of Glycerol to Acrolein and a Scale up in a Pilot Plant”, such as
51
HZSM5, H Beta Zeolite, Phosphated zirconia and WO3/ZrO2. He found out that
experiments carried out with the WO3/ZrO2 catalyst are the most promising. The
data on his experiments is as follows.
Tungsten zirconia catalysts based from US Patent 2006/0091045 (Figueras
et al.) provide an alternative to reactions which are catalyzed by means of acid
sites and they are deactivated to a lesser extent. With high melting point at 3003
K, low thermal conductivity and high resistance to corrosion, Zirconium oxides or
zirconia (ZrO2) is widely used as catalyst. M.A. Cortes-Jacome et al. on Journal of
Solid State Chemistry 179 (2006) discussed on their study with title “Generation
of WO3-ZrO2 catalysts from solid solutions of tungsten in zirconia” that zirconia
modified with sulphate, phosphate, heteropolyacids HPA, tungsten and
molybdenum has emerged as an alternative catalysts to substitute chlorinated
alumina and liquid acid catalysts because zirconia based catalysts can be
regenerated easily. Among those different modifications, tungsten oxide dispersed
on zirconia seems to be the most stable. Prieto reported that tungsten zirconia
52
catalysts offer inherent advantages from the standpoint of industrial application,
such as higher stability under high-temperature treatments, lower deactivation
rates during catalysis, and easier regeneration.
Reaction of the dehydration of glycerol to acrolein is given in this mechanism.
Summary of the above mechanism is given below
Aqueous glycerol which is the major by-product during the biodiesel
production is supplied to the reactor. US Patent 2010/0168471 discussed that
dehydration reaction is carried at a temperature of between 150 °C and 500 °C,
preferably between 250 °C and 350 °C, and at a pressure between 1 and 5 bar,
preferably between 1 and 3 bar. Ulgen et al. stated that at temperatures higher than
240 °C, glycerol is extensively converted. The acrolein selectivity, however,
53
shows a maximum at 280 °C. At lower temperatures the intermolecular
dehydration, yielding oligomers of glycerol, is thermodynamically favoured over
the desired intramolecular dehydration forming acrolein. At temperatures higher
than 280 °C, the formation of CO and CO2 is possible. These two reasons are
responsible for the selectivity decrease of acrolein. That is also supported by the
fact that the untrapped product mass increased with rising temperatures, from 0.1
wt% at 240 °C to 2.0 wt% at 320 °C. In the mini review “Glycerol as a Source for
Fuels and Chemicals” conducted by X. Fan et al., they reported that a study has
been conducted showing lower pressures are effective for rapid removing the more
volatile products from the catalyst sites thus achieving a long catalysts service life.
Prieto included in his study that when the glycerol solution reaches 200 °C,
the mixture is completely evaporated. Between 104 and 200 °C, the system is a
mixture of liquid and vapor. The molar composition of the vapour fraction, y1, can
be obtained by reading on the condensation curve, and the molar composition of
the liquid fraction, x1, by reading on the vaporization curve. The dehydration of
glycerol leads to acrolein as a main product. He concluded that the glycerol
conversion has the following findings:
• Increases with the temperature because the dehydration of glycerol to
acrolein is endothermic. However, the kinetic can limit the process.
• Decreases when concentrated glycerol solutions are used.
54
• Decreases when high glycerol solution feed flows are used. That is
expected because faster feed flows achieve lower residence times.
While the selectivity of acrolein have these
• Increases with the temperature until approximately 280 - 285 °C, and then
decreases a little.
• Decreases with the glycerol concentration.
• Increases with the glycerol solution feed flow.
“An approach for finding an optimum working point can be determined. To
get a complete glycerol conversion it is better to work at high temperatures.
Around 280 °C the acrolein production is the highest. However, at higher
temperatures, close to 300 °C, the formation of acrolein decreases a little, and the
formation of by-products increases with the temperature. Therefore, a
temperature, around 285 °C will be appropriate to produce the highest amount of
acrolein at a complete glycerol conversion and to minimize the formation of by-
products. The glycerol concentration should be not too high because at high
glycerol concentrations, the glycerol conversion and acrolein selectivity
decreases.”
According to the US Patent 5387720, “gas phase reaction is preferable
since it enables a degree of conversion of the glycerol of close to 100% to be
obtained. A proportion of about 10% of the glycerol is converted into acetol,
which is present as the major by-product in the acrolein solution.”
55
Prieto also reported that “An appropriate feed flow could be the minimal
flow, which produces complete conversion or close to 100 % and high acrolein
selectivity, but not too high to avoid the formation of acetol.”
“In the previous analysis, it was predicted that a temperature near 280 °C
achieves the highest acrolein selectivity at complete glycerol conversion. Now, the
optimization results can be examined with temperatures between 274 and 290 °C.
However, the solutions, which achieve the highest selectivity for acrolein, show
that the optimal temperature is around 275 - 280 °C. Keeping in mind the kinetic
effect over the reaction, high temperatures will favor the reaction. However, over
290 °C neither complete glycerol conversion nor high acrolein selectivity is
reached. The explanation to this effect could be due to the boiling point of pure
glycerol. Over 290 °C pure glycerol burns, which leaves less glycerol to be
converted into acrolein and, of course, less acrolein to be produced. This effect
can explain why at high temperatures the reaction works not so well, even being
an endothermic reaction. The effect of the glycerol burning has to be also taken in
account.”
56
Removal of Water-Rich Stream by Absorption
Absorption is further utilized to achieve high purity of acrolein coming
from the stream produced in the dehydration reactor. According from the work of
Jean-Luc Dubois entitled Method for Preparing Acrylic Acid from Glycerol (US
Patent No. 2010/0168471),
“The invention relates to a method for preparing acrylic acid from an
aqueous glycerol solution, comprising a first step of dehydration of the glycerol to
acrolein, in which an intermediate step is implemented, consisting in at least
partly condensing the water and heavy by-product present in the stream issuing
from the first dehydration step.”
“The solution provided by the invention constitutes an optimization
between the quantity of water fed to the first stage dehydration reactor and the
quantity of water introduced into the second stage oxidation reactor. The solution
consists in at least partly condensing the water present in the stream issuing from
the dehydration reaction of the aqueous glycerol solution, to prevent the second
stage catalyst from being deactivated too rapidly, on the other hand, and to
prevent the acrylic acid solution produced from being too dilute, on the other.”
“In the method according to the invention, the expression at least partly
condensing means that 20% to 95%, preferably 40% to 90%, of the water present
57
in the stream issuing from the first step is removed in the intermediate step before
being sent to the second stage reactor.”
“The partial condensation unit may be an absorption column optionally
coupled to an evaporator, a heat exchanger, a condenser, a dephlegmator, and
any apparatus well known to a person skilled in the art, serving to carry out a
partial condensation of an aqueous stream.”
“The acrolein-rich stream, stripped of the heavy by-products and most of
the water, is sent to the oxidation reactor where the acrolein can then be oxidized
to acrylic acid with a controlled and higher partial pressure. The productivity of
the reactor is thereby improved.”
“The method according to the invention, even though it requires an
additional unit associated with the intermediate step, has the advantage of using
an economical raw material and of being able to optimize the two reaction stages
separately. This increase the acrylic acid productivity and selectivity. The method
remains demonstrably economical.”
Purification of acrolein is described in the US Patent No. 5770021 entitled
“Process and Apparatus for Purification of a Gas Stream Containing Acrolein”,
“This process includes cooling the reaction mixture in a cooling tower,
where it is brought into contact with condensing liquid, an effluent gas containing
58
predominantly non-condensable and acrolein being recovered at the top of the
tower.”
“Accordingly, the present invention provides a process for the purification
of acrolein present in a feed gas stream including acrolein, water, by-products
and inert gases, originating particularly from the first reactor, which process
comprises, in a first stage, fractionating the feed gas stream into a gaseous
effluent and a liquid stream in a cooling column operating such that the
temperature of the liquid stream at the bottom of the column is lower than or
equal to the condensation temperature of the feed gas stream, the difference in the
temperature not exceeding 20°C, preferably not exceeding 10°C; and then, in a
second stage, condensing the gaseous effluent at a temperature that is lower the
20°C to give a liquid fraction and a purified gaseous fraction.”
“As used herein, the term “inert gases” is intended to mean all of the
gaseous compounds that remain in the gaseous phase from the beginning to the
end of the production process of the invention and that are found in the purified
gaseous fraction after condensation stage. In this respect, the inert gases in the
mixture to be purified may, in what follows, be occasionally called “non-
condensable” since they are not condensed under the temperature and pressure
conditions used in the process of invention. The inert gases generally include
nitrogen, oxygen, and other gases from air.”
59
“The circulation of the gaseous stream in the column counter-currentwise
to a cold liquid result in condensation of the water and other condensable
components that may be present. The condensed liquid flows back down under
gravity to the bottom of the column. The gases at the top of the column are
depleted in impurities and include acrolein and non-condensable gases. The
temperature of the gases at the top of the column preferably ranges from 30° to
60°C, and still more preferably from 50° to 60°C.”
“The temperature of the liquid stream at the bottom of the column is
preferably less that 20°C, and more preferably less than 10°C, lower than the
condensation temperature of the feed gas stream. Preferably, the temperature of
the liquid stream at the bottom of the column is substantially equal to the
condensation temperature of the gaseous mixture introduced into the column to
reduce to a minimum condensation of acrolein and degradation; in most cases it is
lower than 100°C. The condensation temperature of the gaseous mixture
originating from the catalytic dehydration of glycerol preferably ranges from 70°
to 90°C, at a pressure of approximately 1.2x105 Pa.”
“The cooling column preferably operates at a pressure ranging from 105 to
3x105 Pa. The recycled stream generally contains organic acids and preferably
less than 2%, more preferably less than 1.5%, by weight of acrolein and at least
90% by weight of water.”
60
Oxidation of Acrolein to Acrylic Acid
Acrylic acid is used as a precursor for a wide variety of chemicals in the
polymers and textile industries. Direct synthesis of acrylic acid from glycerol is an
attractive approach since it is useful as raw material for various synthetic resins,
paints, fiber etc. The process involves two steps, a dehydration of glycerol to
acrolein which was mentioned earlier followed by gas-phase catalytic oxidation
carried out with an oxide catalyst. Oxidation of acrolein to acrylic acid has been
known since late 1960s attached with the manufacture of acrylic acid from
propylene but Prieto reported that crude oil is still the main propylene source and
we cannot afford to utilize more crude oil due to its scarcity. Using raw material
like glycerol will be an alternative also it has the advantage of being renewable
meeting the criteria connected to the concept of “green chemistry”.
According to J. Tichy in his work refer to “Oxidation of acrolein to acrylic
acid over vanadium-molybdenum oxide catalysts”, he reported that “oxidation of
acrolein proceeds favourably with a stoichiometric excess of oxygen, and the
reaction temperature should not exceed 573 K or else it will yield an undesirable
radical reaction”. He also believed that among the recommended catalysts, the
most efficient system for the conversion of acrolein to acrylic acid involve oxide
systems based on Mo-V, Mo-Co, V-Sb and heteropolyacids. US Patent
20100168471 also suggested the catalysts made of formulations containing Mo
61
and/or V and/or W and/or Cu and/or Sb and/or Fe should be used in the catalytic
reaction.
The present invention (US 5264625) based on the patent made by
Hammon, et. Al, “Catalytic Gas-phase Oxidation of Acrolein to Acrylic Acid”,
aims to provide a process for the catalytic gas-phase oxidation of acrolein to
acrylic acid in an fixed bed reactor having contacting tubes, at elevated
temperature on catalytically active oxides with a conversion of acrolein for a
single pass of ≥95%.
“We have found that this object is highly achieved wherein the reaction
temperature in the flow direction along the contacting tubes (along the reaction
axis) in a first reaction zone before the starting reaction gases containing the
reactants enter the contacting tubes is from 260° to 300°C until a methacrolein
conversion of a ≥95% has been reached, with the proviso that the reaction
temperature in this secondary reaction zone is not lower than 240°C.”
Conversion of crude glycerol to acrylic acid via acrolein as its intermediate
step is shown in this stoichiometric reactions.
62
Oxidation reaction from acrolein to acrylic acid.
Based on the US Patent 20100168471, oxidation reaction takes place at
temperature of between 200 °C and 350 °C, preferably from 250 °C to 320 °C and
under the pressure of between 1 and 5 bar. The reaction is carried out in the
presence of molecular oxygen which may be in the form of air having a content of
between 3 to 20% by volume, with regard to the incoming stream and optionally
in the presence of inert gases such as N2. The inert gases necessary for the method
may be optionally consist in full or in part of gases obtained at the top of the
absorption column.
US Patent 5264625 described the oxidation process is highly exothermic. It
is therefore required to control the reaction temperature in order to obtain a highly
selective conversion of acrolein to acrylic acid. Industrial production of acrylic
acid is at present carried out by vapour phase catalytic oxidation of acrolein.
A tandem reaction of dehydration and oxidation process of converting
glycerol to acrylic acid was made by Prieto. He said that the experiment ran
successfully and acrolein was completely converted to acrylic acid.
63
“In the Figure 4.23, the experiment ran successfully. No acrolein was
found anymore. That means a complete oxidation to acrylic acid took place. Other
by-products, like acetic acid and propionic acid were also observed. Due to the
oxidation, acetaldehyde and propanal were oxidized to their correspondent acids.
It is important to mention that mass loss was observed during the reaction. In the
Figure 4.23, after the first hour of the reaction no products were found. Almost a
mass loss of 100 % in carbon mass was observed. This can be explained due to the
amount of oxygen used in the reaction (see section 4.4.3.2 and Figure 4. 24). The
percentage of mass loss decreases with the reaction time, as long as acrylic acid
and other by-products such acetic and propionic acid, were formed. At the
stationary-state around 25 % of mass loss was found. Around 40 % of acrylic
64
acid, 10 % of acetic acid and 3 % of propionic acid were found. The 25 % of mass
loss should be due to the burning of compounds on the catalytic particles.”
“For the oxidation reaction, the reaction temperature in the oxidation
catalyst increases gradually during 140 minutes, and after that, it remains
constant at 310 °C. This means that the oxidation reaction is taking place. The
higher the reaction temperature in the oxidation catalytic bed, the higher is the
formation of acrylic acid. Once the temperature is stabilized at 310 °C, the
formation of acrylic acid remains also constant at around 40 %. After 300
minutes, when the oxygen flow was switched off, the temperature of the oxidation
catalytic bed dropped to 286 °C. That means, that no exothermic reaction was
taking place and in consequence no acrylic acid was formed.”
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Esterification of Acrylic Acid to form Ethyl Acrylate
Various acrylic esters are useful chemicals. Esterification of acrylic acid
with alcohol has commercially been performed by using liquid catalysts such as
sulfuric acid, hydrofluoric acid, and para-toluenesulfonic acid; however these are
toxic, corrosive and often hard to remove from the solution.
From US Patent 20050107629 – Method for Producing Ethyl Acrylate by
Rohm and Haas Company: “The present invention is directed to a continuous
process for producing ethyl acrylate and for recovering acrylic acid, ethyl
acrylate, ethanol and water from an esterification reactor mixture containing
acrylic acid, ethyl acrylate, ethanol, water and acid catalyst.”
“This invention relates to a method for combining acrylic acid and ethanol,
and processing the reaction products to produce ethyl acrylate in improved yield.
Fresh crude acrylic acid, ethanol, and esterification catalyst are fed to the
esterification reactor. Typical components of the bottoms stream comprise acrylic
acid, at 60 to 90% and acrylic acid dimer (AOPA), at 10 to 40%. The acrylic acid
from the bottoms stream comprises from 5% to 15% of the total acrylic acid fed to
the esterification reactor. The molar ratio of acrylic acid to ethanol is from 1 to
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1.1 to 1 to 1.5, preferably from 1 to 1.1 to 1 to 1.2. The esterification reactor
temperature is maintained at from 85° C. to 105° C., at reactor pressures from
220-320 mm Hg. At least one heat exchanger may be used to control the
temperature of esterification reactor.”
According to US Patent 3458561 (Esterification of Acrylic Acid), “the
minimum temperature at which the esterification is achieved depends upon the
boiling point of the formed acrylic acid ester, of the azeotrope formed from the
acrylic acid ester and water, respectively, as well as whether one uses
subatmospheric pressure, atmospheric pressure, or super-atmospheric pressure.
In general, temperature between 70 to180 °C is employed.”
“This invention relates to a novel process for esterifying acrylic acid, more
specifically this method pertains to a novel combination of variables which results
in the obtention of acrylic acid esters in high yields by a simplified and more
economical esterification which combination also includes the ester product
recovery. A number of processes are known which are directed to the conversion
of acrylic acid and an alcohol to the corresponding acrylic ester in the presence of
an esterification catalyst. However, the following problems exist: (a) ethyl
acrylate, ethanol and water form an azeotrope boiling at 77.1° C, at a pressure of
760 mm. Of mercury, which azeotope at a rather great expense can be processed
further to recover the ester product; (b) the polymerization tendency of acrylic
67
acid and its ester reduces to a considerable degree the alternatives which may be
taken when carrying out the esterification reaction.”
“Esterification of acrylic acid is possible in a liquid as well as in a gas
phase. Of primary importance as an esterification catalyst is sulfuric acid and/ or
a sulfonic acid. In respect to the amounts at which these catalysts have been
utilized, the catalyst should be used in amounts such as about 0.01% sulphuric
acid per mole of acrylic acid. In order to achieve the desired reaction, the
reduction of the formation of a ternary azeotrope of the ester, alcohol and water
and obtaining only the ester-water mixture, contrary to the heretofore recognized
methods, exceptionally large amounts of acid are necessary such as from 5 to 50%
by weight of sulfuric acid or 10 to 80% by weight of the above describe sulfonic
acid. Preferably an amount of the acid is chosen, which comprises 7 to 35% by
weight of the sulfuric acid or 20 to 70% by weight of the sulfonic acid on the basis
of the reboiler contents. Considering the esterification speed and conversion and
avoiding at the same time the formation of undesirable side reactants, the best
results are obtained when using in the reboiler from 10 to 25% by weight of
sulfuric acid or 30 to 50% by weight one of the aforementioned sulfonic acid with
a residence time of 3 hours.”
The reaction of acrylic acid and alcohol is as follows:
68
From US Patent No. 20050107629, “Reacting the acrylic acid and ethanol
to yield ethyl acrylate in a conversion of at least 90% on acrylic acid, and yielding
the esterification reaction mixture comprising ethyl acrylate, acrylic acid, ethanol
and water.”
From Biochemical Engineering Journal 41 (2008) 87–94 by G.N. Kraai et
al., “In esterification reactions, a batch reactor equipped with four baffles and a
six-bladed turbine impeller is used.”
From Turbine & High Efficiency Axial Flow Agitators,
http://www.feldmeier.com/cutsheets/turbine_agitator.pdf, “The speed range for
commercially available turbine agitator is 63 to 73 rpm.”
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Purification of Ethyl Acrylate by Pervaporation
Among the different membrane separation technologies, pervaporation is
presently considered as a process unit with high potential to recover organic
compounds from aqueous organic mixtures using hydrophobic membranes. This
application is of particular interest to the chemical industry since integration of
pervaporation into waste water treatment includes the opportunity to recover
organic compounds to a standard that both water and organic compounds could be
reused without additional processing. Hence this approach might offer both
environmental and economical benefits to industry. Pervaporation is characterized
by the evaporation of water from permeate side. In vacuum pervaporation, the heat
required for evaporation is supplied from the feed side. Consequently, there will
be a temperature gradient in direction of the feed.
A major problem in the esterification of polyacrylic or methacrylic acid is
removing water from the reaction mixture during its production due to the
presence of an azeotropic water-alcohol mixture. Sometimes the boiling points of
alcohol and water are very close and sometimes some crosslinking reaction occurs
at high temperature. The extraction of water from the reaction mixture using a
traditional technique such as distillation is a non-economical method.
Pervaporation is an energy efficient and high selective extraction process for the
extraction of volatile products and for the dehydration of organic chemicals. The
productivity and conversion rate can be significantly increased.
70
From EP 2325214A1, the present invention relates to the synthesis of ethyl
acrylate by esterification of acrylic acid with alcohol assisted by the pervaporation
technique for extracting water.
“A major problem in the esterification of polyacrylic or methacrylic acid is
removing water from the reaction mixture during its production due to the
presence of an azeotropic water-alcohol mixture. Sometimes the boiling points of
alcohol and water are very close and sometimes some crosslinking reaction
occurs at high temperature. The extraction of water from the reaction mixture
using a traditional technique such as distillation is a non-economical method.”
“The object of the present inventions is further solved by a use of a
membrane in the production of acrylate ester, for extracting water produced
during esterification of acrylic acid with alcohol in the presence of an acid as
catalyst. In one embodiment of the use, the membrane comprises or is made of
polyvinylalcohol modified and crosslinked with a crosslinking agent at 2-6 weight-
%, preferably at 2-5 weight-%, using different technique. In one embodiment of
the use, the membrane has a thickness of about 5-200υm, preferably of about 22-
55 υm, most preferably of about 25 υm. The method according to the invention
allows for the production of copolymers and terpolymers at controlled
composition (0-99 %mole). The pervaporation apparatus employed in this
invention is similar to that used by different authors, such as Bing Cao et al.”
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“Pervaporation is an energy efficient and highly selective extraction
process for the extraction of volatile products and for the dehydration of organic
chemicals. The productivity and conversion rate can be significantly increased
when the reaction is coupled with pervaporation, i. e., a pervaporation reactor.
Techno-economic studies revealed that pervaporation reactors have good market
potential in process industries.”
“The combination of an esterification reaction of polyacrylic or
polymethacrylic acid with a pervaporation process increases the conversion of
reversible reactions, such as esterification, by removing selectively the water
formed from the reacting mixture. Thus, the yield of the conversion is greatly
enhanced.”
“An esterification reaction between an alcanol and a carboxylic acid in the
presence of a catalyst is a reversible reaction, and a high industrial conversion
can be achieved by adding a large excess of acid. A water selective pervaporation
membrane can be used in the esterification reactor. This can shift the equilibrium
to the right, thus reducing excess reactants.”
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B. PRODUCT LITERATURE
Ethyl acrylate is an organic compound primarily used in the preparation of
various polymers. Ethyl acrylate can be prepared by several industrial methods.
Acrylonitrile can be reacted with ethanol using sulfuric acid as a catalyst to
produce ethyl acrylate. It may also be prepared from acetylene, carbon monoxide
and ethanol. Ethyl acrylate is used to form paint coatings that is resistant to water,
sunshine, and weather. These coatings retain flexibility even at low temperatures.
EA is also used in industrial finishes and coatings for cans and coils. Fabrics gain
texture and durability when ethyl acrylate is added during their manufacture. Ethyl
acrylate also imparts dirt resistance, improves abrasion, and binds pigments to
fabric. Paper is coated with ethyl acrylate to make it water-resistant. Magazines,
books, business paper, frozen food packaging, and folding boxboards have such
coatings, making them resistant to water, grease, and oil. Ethyl acrylate is also
used in adhesives for envelopes, labels, and decals. Caulk, glazing, and various
sealants also contain Ethyl acrylate. Leather products, such as automotive
upholstery, furniture, clothing, and shoes contain EA so that top coatings do not
migrate. Ethyl acrylate is also used as a fragrance additive in various soaps,
detergents, creams, lotions, perfumes, and as a synthetic fruit essence. Ethyl
acrylate is also found in such household items as nail mending kits and in medical
items that assist with the binding of tissues, sealing wounds, etc.
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Acrylic esters make the main product derived from acrylic acid. They
account for 55% of global demand. About half of the crude acrylic acid is
processed to purified (glacial) acrylic acid, which is further processed both on-site
(captive use) and by external downstream users. The other half of crude acrylic
acid is transformed into various acrylate esters at the production sites. Identical to
glacial acrylic acid, these acrylic esters serve as commercial products, which are
further processed both on-site and by external downstream users. Glacial acrylic
acid is used in the manufacture of super absorbing polymers (SAP), which account
for 32% of the global demand for acrylic acid. Acrylic acid and basic alkyl esters
(methyl, ethyl, butyl and 2-ethylhexyl esters) are used for the manufacture of
polymer dispersions, adhesives, super absorbent polymers, flocculants, detergents,
varnishes, fibres and plastics as well as chemical intermediates.
“Greater attention is now paid to environmental protection and energy
saving. Research organizations and production enterprises are developing and
disseminating various environmental protection and energy saving technologies.
The radiation curing technology takes special acrylic esters as major raw
materials and UV rays or electron beams as initiators to polymerize acrylic esters
into polymer films. Compared with conventional polymerization methods, this
technology does not use chemical initiators, polymerization takes place at normal
temperature and no heat is used. Initiators are saved and energy consumption is
reduced.
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“Acrylic esters and derivatives represent about 65 per cent of the market
for acrylic acid in the USA, slightly higher than in Australia.”
“Acrylates are used in a broad range of applications directly as a resin, or
as solution or emulsion. The following provides an indication of typical
applications with the market share expressed as a percentage of all acrylic acid
applications as acrylic acid (ie. including the previously described polyacrylic
acids).”
“Surface coatings, such as paints, represent the largest application for
acrylic esters at about 19 per cent of the market. Demand, that was motivated by
the convenience of water-based paints especially the superior acrylic-based
emulsions, is now being driven by regulations and interests to reduce atmospheric
release of volatile organic compounds (VOCs) used as solvents in traditional
(alkyd-based) surface coatings. This sector is growing at 3 to 5 per cent per year
with faster growth for newer more sophisticated applications (such as UV
radiation-curable polymers).”
“The Australian surface coating industry is dominated by ICI Australia,
Wattyl and Taubmans using emulsions made by companies such as Rohm and
Haas and BASF from imported ethyl and other acrylic esters. The paint industry in
Australia, like in other developed countries, is growing at about 2 per cent per
year.”
75
“Adhesives and sealants are the second largest application for a broad
range of esters that represents about 15 per cent of acrylic acid applications.
Though this sector is closely related to the variable and slower growing
construction sector, like the surface coating sector it has been stimulated by
concerns about VOCs. This sector has been growing at 4 to 6 per cent per year in
most markets and faster in Asian textile-producing regions with growing
construction sectors.”
“Textiles represent about 11 per cent of the market for acrylic esters in the
USA of which about 90 per cent is used as emulsions for use in non-woven fabrics
and textile treatment, and only 10 per cent for textile fibres. Growth in the USA
has been about 2 per cent but substantially faster in some Asian countries.”
“A range of acrylic esters are used to produce plastic forms and sheets
representing about 8 per cent of the market that is growing at about 3 per cent.”
Demand has increased for acrylic acid derivatives, specifically ethyl
acrylates used in the production of surface coatings. Still, the growth is being
limited by the current global inventory of crude acrylic acid. Due to growing
demand for acrylic acid derivatives led by SAPs, many of the major producers
have responded by expanding plants and building new production facilities at key
sites throughout the world.
76
2005 2006 2007 2008
China,
People's Republic 12,630 3,004 204,234 49,296
Indonesia
(Includes West Irian) 566,880 248,345 417,487 643,563
Japan
(Excludes Okinawa) 143,065 106,540 738,500 235,582
Korea,
Rep. of (South) 1,547,700 1,631,096 1,400,716 1,026,230
Malaysia
(Federation of Malaya) 1,572,684 1,913,767 7,425,932 6,851,514
Singapore 1,373,245 1,674,298 1,457,535 4,571,053
South Africa,
Rep. of 326,445 650,925 23,550 -
Table 2.1. Countries that Produce Ethyl Acrylate (kg)
COUNTRIES
YEAR
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C. RAW MATERIAL LITERATURE
• Glycerol
Glycerol, propane-1, 2, 3-triol, glycerin, a trihyhdric alcohol, is a clear,
water-white, viscous, sweet-tasting hygroscopic liquid at ordinary room
temperatures above its melting point. Glycerol occurs naturally in combined form
as glycerides in all animal and vegetable fats and oils, and is recovered as a by-
product when these oils are saponified in the process of manufacturing soap, when
the fats are split in the production of fatty acids, or when fats are esterified with
methanol in the production of methyl esters.
The uses of glycerol number in thousands, with large amounts going into
the manufacture of drugs, cosmetics, toothpaste, methane foam, synthetic resins
and ester gums. Tobacco processing and foods also consume large amounts either
as glycerol or glycerides.
Glycerol was introduced by Sergio Sabater Prieto to his work Optimization
of the Dehydration of Glycerol to Acrolein and a Scale up in a Pilot Plant.
“Glycerol is the common name of propane-triol. It is a sweet tasting,
highly viscous colorless and odorless liquid with no known toxic properties.”
“Glycerol has many direct utilization fields, such as cosmetics, lubricants
or explosives, and other 1300 applications, but not enough market possibilities to
take all the glycerol from diesel production.”
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“Glycerol is a side-product of bio-diesel production. Natural oils are
triglycerides. The transesterification of one mole of such an oil yields three moles
of hydrocarbon chains and one mole of glycerol. The hydrocarbon chains are used
as bio-diesel fuels. Due to the developments in the bio-diesel industry, the glycerol
production is also increasing. Since the demand for glycerol is not increasing with
the same tendency, the glycerol price is decreasing, which makes it an interesting
carbon source for intermediates.”
“The dehydration of glycerol to acrolein is an adequate reaction with
interesting economic and environmental aspects.”
“Bio-diesel is produced from agricultural products and not from crude oil.
Glycerol is formed as a by-product during the transesterification process, which is
the key step for the production of bio-diesel.”
“The use of glycerol produced during the bio-diesel process has potential
to be an environmentally carbon source for the production of acrylic acid.
Moreover, the economical valorisation of glycerol makes the bio-diesel production
more attractive. Replacing propylene by glycerol would be an indirect step for
improving the sustainability in environmental care.”
“It is known that crude oil price is increasing. In connection to that, the
propylene price increases as well, since it is mainly crude oil based. On the other
hand, glycerol prices are decreasing. The reason: Glycerol is not an important
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intermediate. It is mostly used in small amounts for cosmetics and for the food
industry. Global glycerol demand is not increasing so fast as the bio-diesel
production. The following diagram compares the price evolution of propylene and
different qualities of glycerol.”
In the thesis made by Denver J. Pyle with title “Use of Biodiesel-Derived
Crude Glycerol for the Production of Omega-3 Polyunsaturated Fatty Acids by
the Microalga Schizochytriumlimacinum”, the crude glycerol produced during the
biodiesel production process is impure and of little economic value.
“The impurities include methanol and soaps. Biodiesel producers use
excess methanol to drive the chemical transesterification and do not recover the
entire methanol. Therefore, it is present in the glycerol layer. Also, free fatty acids
present in the initial feedstock can react with the base to form soaps that are
soluble in the glycerol layer. In addition to methanol and soaps, crude glycerol
also contains a variety of elements such as calcium, magnesium, phosphorous, or
sulfur.”
“It has been reported that glycerol makes up anywhere from 65% to 85%
(w/w) of the crude glycerol streams (Gonzalez-Pajuelo et al., 2005; Mu et al.,
2006). The remaining weight in the crude glycerol streams is mainly methanol and
soaps. The wide range of the purity values can be attributed to different glycerol
purification methods used by the biodiesel producers and the different feedstocks
used in biodiesel production. For example, Thompson and He (2006) have
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characterized the glycerol produced from various biodiesel feedstocks. It was
found that the crude glycerol from any feedstock is generally between 60 and 70 %
(wt) glycerol. Mustard seed feedstocks had a lower level (62%) of glycerol, while
soy oil feedstock had 67.8 % glycerol and waste vegetable had the highest level
(76.6 %) of glycerol.”
According to US Patent 2008/0249338 (Method for Purification of
Glycerol), aside from glycerol, crude glycerol from biodiesel production typically
contains methanol, water, inorganic salts and salts of fatty acids.
“Levels of inorganic salts typically are from 5% to 50%. Levels of
inorganic salts are from 1% to 5%. These levels typically are expressed together
in terms of total cation concentration, which usually is from 0.2% to 5%. Crude
glycerol contains water, and may also be diluted further with water to reduced
load on the column and aid in the separation, so that typical water levels can be
from 5% to 40%. In some embodiments of the invention, glycerol concentration in
the crude glycerol introduced into the resin bed is at least 20%, alternatively at
least 30%, alternatively at least 40%, alternatively at least 50%, alternatively at
least 60%, alternatively at least 70%, alternatively at least 75%.
81
• Air
The air around us is a mixture of gases, mainly nitrogen and oxygen, but
containing much smaller amounts of water vapor, argon, and carbon dioxide, and
very small amounts of other gases. Air also contains suspended dust, spores, and
bacteria. Because of the action of wind, the percent composition of air varies only
slightly with altitude and location.
Air retrieved from http://scifun.chem.wisc.edu/chemweek/pdf/airgas.pdf
“The amount of water in the air varies tremendously with location,
temperature, and time. In deserts and at low temperatures, the content of water
vapor can be less than 0.1% by volume. In warm, humid zones, the air may
contain over 6% water vapor.”
“Air is the commercial source for many of the gases it contains. It is
separated into its components by fractional distillation of liquefied air. Before air
is liquefied, water vapor and carbon dioxide are removed, because these
substances solidify when cooled and would clog the pipes of the air liquefaction
plant. The dry, CO2-free air is compressed to about 200 atmospheres. This
compression causes the air to become warm, and the heat is removed by passing
the compressed air through radiators. The cooled, compressed air is then allowed
to expand rapidly. The rapid expansion causes the air to become cold, so cold that
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some of it condenses. By the alternate compressing and expanding of air, most of
it can be liquefied.”
“Nearly all commercial oxygen (over 95%) is produced by fractional
distillation of liquid air. It boils at -183EC. Oxygen is the third highest-volume
chemical produced in the U.S., and most of this product is more than 99.5% pure.
Oxygen is paramagnetic, that is, it is attracted to a magnet. Liquid oxygen is pale
blue. The major commercial uses of oxygen are in metal manufacturing (30%),
metal fabricating (33%), and in health services (13%). In the steel industry,
oxygen is passed through impure molten iron in a blast furnace to oxidize and
remove impurities such as carbon, sulfur, phosphorus, and silicon. Oxygen is also
used as the oxidant in torch cutting of steel. In this process, the steel is heated by
an oxygen-acetylene flame, and a stream of hot oxygen is directed at the hot steel.
The hot steel is oxidized by the hot oxygen and erodes away, severing the steel.
Oxygen is also used extensively in the chemical industry, such as in the production
of nitric acid, HNO3, from ammonia, NH3.”
Oxygen occurs mainly as an element in the atmosphere. It makes up 20.948
percent of the atmosphere. It also occurs in oceans, lakes, rivers, and ice caps in the form
of water. Nearly 89 percent of the weight of water is oxygen. Oxygen is also the most
abundant element in the Earth's crust. Its abundance is estimated at about 45 percent in
the earth.
83
Oxygen also reacts with many compounds. Combustion is one of the
examples, that is, it helps other compounds to burn. Another is oxidation. From
the term itself, it is the addition of oxygen to a compound yielding another kind of
compound.
The process of oxidation of acrolein to form acrylic acid was done with the
aid of a catalyst. The best suited catalyst used is a multi-metal oxide which in the
case of this process is the vanadium-molybdenum oxide catalyst.
Oxygen occurs in all kinds of minerals. Some common examples include
the oxides, carbonates, nitrates, sulfates, and phosphates. Oxides are chemical
compounds that contain oxygen and one other element. Calcium oxide, or lime or
quicklime (CaO), is an example. Carbonates are compounds that contain
oxygen, carbon, and at least one other element. Sodium carbonate, or soda, soda
ash, or sal soda (Na2CO3), is an example. It is often found in detergents and
cleaning products.
Nitrates, sulfates, and phosphates also contain oxygen and other elements.
The other elements in these compounds are nitrogen, sulfur, or phosphorus plus
one other element. Examples of these compounds are potassium nitrate, or
saltpeter (KNO3); magnesium sulfate, or Epsom salts (MgSO4); and calcium
phosphate (Ca3(PO4)2).
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• Tungstated Zirconia Catalyst
Prieto discussed the effect of tungsten zirconia in his dissertation entitled
Optimization of the Dehydration of Glycerol to Acrolein and a Scale up in a Pilot
Plant.
“Tungsten zirconia materials are very attractive, environmentally friendly
solid acids. Although less active than their sulfate-promoted counterparts,
tungston zirconia catalysts offer inherent advantages over the former from the
standpoint of industrial application, such as higher stability under high-
temperature treatments, lower deactivation rates during catalysis, and easier
regeneration7. A minimum level of WOx is required to stabilize the tetragonal
phase of the zirconia support on annealing in air at high temperatures (typically
973 – 1173 K) needed to produce catalytically active materials. Iglesia and co-
workers reported that the acid activity of WOx-ZrO2 materials is a unique
function of the tungsten surface density rather than the W loading or calcinations
temperature independently. When this parameter is considered, a maximum in the
catalyst activity is found at intermediate values of the tungsten density. It has been
proposed that strong Brönsted acid sites responsible for the high catalytic activity
of WOx-ZrO2 develop on reduction of W+6 species in the presence of H2 or other
reductants, such alkanes or alcohols, to compensate the excess of negative charge
in the polyoxotungstated domains. These types of acid sites are termed temporary
acid sites, in opposition to the permanent acidity present in calcined WOx-ZrO2
85
samples. By themselves, the latter acid sites cannot account for the observed
catalytic activity. At tungsten coverages well below the monolayer, isolated
monotungstate species predominate on the zirconia surface. These species are
difficult to reduce and thus do not allow the formation of catalytically active
Brönsted acid sites. In contrast, highly reducible three-dimensional WO3
crystallites coexist with the two-dimensional amorphous polytungstates at
coverages exceeding the monolayer, resulting a decreasing accessibility to the
active WOx species. Thus, the occurrence of a maximum in the catalytic activity at
intermediate WOx surface densities represents a compromise between the
accessibility to the surface WOx species and their reducibility.”
Ulgen et al. Conversion of Glycerol to Acrolein in the Presence of
WO3/ZrO2 Catalysts discussed that “ZrO2 powder and WO3/ZrO2 pellets with 19
wt% WO3 were kindly provided by St. GobainNorpro, Ohio, USA. WO3/ZrO2
powders with five different WO3 contents (between 2.11 and 15.43 wt% WO3)
were obtained from Daiichi KKK, Japan, via Arkema CRRA, France. In these
cases there is nothing disclosed about the method of preparation. These Daichii
KKK catalysts were used without prior modification.”
“Several homemade catalysts have been prepared according to the
following impregnation method recipe, which was conducted under ambient
atmosphere. A certain amount of ammonium (para) tungstate (Sigma Aldrich,
Germany) and 200 mL of water were heated to 80°C and stirred 2 h, yielding a
86
clear solution. Into this solution, ZrO2 (Provided by St. Gobain/Norpro, Ohio,
USA) was added and stirred for another 4 h. After evaporation of the water, the
remaining slurry was placed in a ceramic bowl and dried 6 h at 110°C followed
by calcination at 600°C for 6 h. Both drying and calcination steps were conducted
in a box shaped programmable oven (Nabertherm N 7 with a Logotherm S 19
Program Controller, Tmax = 1,000°C) under ambient pressure and atmosphere
without addition of any gases.”
“The obtained powder was formed to pellets under 10 tons for 20 min,
which was then crushed and sieved. A fraction of 0.5–1.0 mm particle size was
used for the characterisation and screening experiments.”
Figueras, F. et al. Tungsten Catalyst with US Patent No. 2006/0091045
stated that “Zirconia oxide or zirconia (ZrO2) is a solid which used in catalysis.
Amongst the physical properties which make it suitable for this application is its
high melting point (3003 K), low thermal conductivity and high resistance to
corrosion by acids.”
“With regard to the chemical properties, zirconia is an amphoteric support,
as in alumina, that can be used in oxidation and reduction reactions.
Crystallization and sintering of the crystallites by means of calcination are not
desirable for use as a support.”
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“Zirconia can be synthesized by various means, such as precipitation in an
aqueous solution of zirconium salts, such as ZrOCl3·8H2O,
ZrO(NO3)·2H2O,ZrCl4, or the sol-gel method.”
“Tungsten/Zirconia (W-ZrO2) catalysts have been known for some time
and provide an alternative to reactions which are catalyzed by means of acid sites.
The advantage which these solids have compared with sulphates is that they are
deactivated to a lesser extent. They have been describes by Hino and Arata as
strong acid catalysts. The definition as a superacid which was initially adopted
has been downgraded and it is now commonly accepted that they are strong acids
which are capable of isomerising linear paraffins into isoparaffins at
approximately 523 K. Since the acid sites have not been able to be identified, these
solids are characterized by a chemical composition and a method of preparation.”
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• Vanadium-Molybdenum Oxide Catalyst
Josef Tichy in his work entitled, Oxidation of Acrolein to Acrylic acid over
Vanadium-Molybdenum Oxide Catalysts accounted that,
“The first reports published in scientific literature which claim the
advantages of vanadium-molybdenum oxide catalysts in the oxidation of acrolein
to acrylic acid are due to Kitahara et al. [1,2]. The authors undertook extensive
research into the catalyst pre-treatment, the weight ratio of constituents, type of
support, magnitude of particles, amount of the active components coated, and the
way of preparation. On the basis of the results obtained they chose as the most
favorable catalyst one containing the components MoO3, V205, and Al203 in the
molar ratio of 8:1:0.4 coated on spongy aluminum with a 17.8 wt% content of the
active constituents. With the acrolein concentration of 3.4 vol%, molar ratio of
oxygen to acrolein equal to 1.65, that of water to acrolein equal to 16.5, the time
factor of 1.64 s, and the temperature of 573 K it was possible to achieve the
acrolein conversion degree of 97.3% and the yield of acrylic acid equal to 85.7%
with the catalyst mentioned. According to the author’s experience, the optimum
oxidation degree of the catalytically effective components was attained when the
catalyst was preliminarily exposed to action of air at temperature of 573 K and
finally stabilized in reduction atmosphere by action of the starting reaction
mixture at 673 K.”
89
“With the aim of improving the properties of vanadium-molybdenum oxide
catalyst and shortening the lengthy process necessary for establishing the
stationary state, the paper [3] suggests the use of ethylenediamine as the reducing
agent directly in its preparation, using SiO2 in the form of aerosil for the support.
The preparation started from two solutions, namely
hexaammoniumheptamolybdate solution and ammonium vanadate solution with
three fold molar amount of ethylenediamine with respect to vanadium. The
solutions were mixed and aerosol was added thereto. The suspension thus
obtained was concentrated at 353 K to give a paste. For perfect homogeneity it is
recommended to use a spray drier. Calcination at 453 K and annealing in air at
573 K gave the optimum catalyst with the molar ratio of Mo:V = 5:1 and with the
content of active constituent on support equal to 30 wt.%. With the catalyst thus
prepared it was possible to obtain 100% conversion of acrolein and 96% yield of
acrylic acid from a gaseous mixture of the following composition (vol%): acrolein
4, oxygen 6.6, steam 25, and nitrogen 64.4. Oxides of carbon and CH3COOH
being determined as the reaction side products. The catalyst specific surface
determined by the BET method from nitrogen adsorption was 57 m2g-1. The
catalyst is blue in color, and amorphous according to the X-ray diffraction. The
crystallization takes place at temperatures above 600 K, but it is accompanied by
a color change to yellow and a substantial loss of activity due to the oxidation of
V4+ to V5+.”
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• Ethyl Alcohol
Ethanol is miscible (mixable) in all proportions with water and with most
organic solvents. It is useful as a solvent for many substances and in making
perfumes, paints, lacquer, and explosives. Alcoholic solutions of non-volatile
substances are called tinctures; if the solute is volatile, the solution is called a
spirit.
Commercial Alcohols have grown to be the largest manufacturer and
supplier of industrial grade alcohol (ethyl alcohol or ethanol). The uses of the
product include industrial applications (such as solvents, detergents, paints,
printing inks, photo-chemical applications, latex processing, dyes, etc.), the
beverage market, medicinal, pharmaceutical and food products.
Because of ethanol's ease of production and because exposure to low
amounts does negligible harm, it has widespread use as a solvent for substances
intended for human contact or consumption, including scents, flavorings,
colorings, and medicines. In chemistry it is both an essential solvent and a
feedstock for the synthesis of other products. Because it burns cleanly, ethanol has
a long history as a fuel, including as a fuel for internal combustion engines.
“Under acid-catalyzed conditions, ethanol reacts with carboxylic acids to
produce ethyl esters and water:”
RCOOH + HOCH2CH3 → RCOOCH2CH3 + H2O
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“For this reaction to produce useful yields it is necessary to remove water
from the reaction mixture as it is formed.”
“Ethanol can also form esters with inorganic acids. Diethyl sulfate and
triethyl phosphate, prepared by reacting ethanol with sulfuric and phosphoric
acid respectively, are both useful ethylating agents in organic synthesis. Ethyl
nitrite, prepared from the reaction of ethanol with sodium nitrite and sulfuric acid,
was formerly a widely-used diuretic.”
(http://www.chemeurope.com/en/encyclopedia/Ethanol.html)
As a reactive chemical, ethanol in common with all alcohols reacts with
acids to produce esters. Examples include ethyl acrylate, which is used as a
reactive diluent in specialised coatings, and ethyl acetate, which is a widely used
solvent in paint and coating formulations. Ethanol is used in the production of
ethylamines, which in turn are reactive industrial chemicals used in downstream
speciality applications including agrochemicals and pharmaceuticals. It can also be
used to make ethoxypropanol, an increasingly used glycol ether solvent in coating
formulations (CEFIC, 2003).
“The relationship of the introduced amounts of acrylic acid and alcohol in
reference to the reboiler content, depends, in general, upon the available
equipment, the amount of the sulfuric acid in the reboiler, and the esterification
temperature.”
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“Esterification of acrylic acid with the necessary amount of ethanol can,
for example, be conducted by adding from one half to twice the amount of acrylic
acid, based on the weight of the reboiler content, when employing about 20% by
weight of p-toluene sulfonic acid in the reboiler, which is at a temperature of 140°
and at a pressure of 760 mmHg.” (US Patent No.3458561)
According the the “Method of Producing Ethyl Acrylate”
(US2005/0107629), the invention relates to a method for combining acrylic acid
(AA) and ethanol, and processing the reaction products to produce ethyl acrylate
(EA).
“Feeding to the esterification reactor acrylic acid and ethanol, in a molar
ratio of from 1 to 1.1 to 1.5, and the acid catalyst; wherein at least a portion of the
acrylic acid is derived from a bottoms stream from a crude acrylic acid distillation
column, said bottoms stream comprising from 60 to 90% acrylic acid.”
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• Sulfuric Acid
Sulfuric acid, H2SO4, is a strong mineral acid. It is soluble in water at all
concentrations. It was once known as oil of vitriol. Sulfuric acid has many
applications, and is one of the top products of the chemical industry. Principal uses
include ore processing, fertilizer manufacturing, oil refining, wastewater
processing, and chemical synthesis.
“Sulfuric acid is a very important commodity chemical, and indeed, a
nation's sulfuric acid production is a good indicator of its industrial strength. The
major use (60% of total production worldwide) for sulfuric acid is in the "wet
method" for the production of phosphoric acid, used for manufacture
of phosphate fertilizers as well as trisodium phosphate for detergents.”
“Sulfuric acid is used for a variety of other purposes in the chemical
industry. For example, it is the usual acid catalyst for the conversion of
cyclohexanoneoxime to caprolactam, used for making nylon. It is used for
making hydrochloric acid from salt via the Mannheim process.”
(http://www.chemeurope.com/en/encyclopedia/Sulfuric_acid.html)
Conversion of carboxylic acid and an alcohol to form its corresponding
ester is done with the presence of an acidic catalyst. Usually, sulfuric acid is used
as a catalyst in the esterification process.
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“Esterification of acrylic acid is possible in a liquid as well as in a gas
phase. Of primary importance as an esterification catalyst is sulfuric acid and/or
a sulfonic acid, e.g., p-toluene sulfonic acid. In respect to the amount at which
these catalysts have been utilized, German Patent No. 1,006,843 and published
German Patent application No. 1,161,259 teach, for example, that the catalyst
should be used in amounts such as about 0.01% sulfuric acid per mole acrylic
acid.” (US Patent No.3458561)
The sulfuric acid is employed in an amount sufficient to both catalyze the
reaction and to serve as a dehydrating agent or desiccant for the by-product water.
Accordingly, the sulfuric acid should be employed in an amount greater than about
0.05 moles per mole of carboxylic acid to be esterified and preferably above 0.1
moles and of sulfuric acid per mole of carboxylic acid, which is sufficient to both
catalyze the dehydrate the water. Most desirably, from about 0.1 to about 0.5
moles of sulfuric acid and most preferably about 0.2 moles will be employed per
mol of carboxylic acid. The reaction is carried out at elevated temperatures,
conveniently reflux conditions. With methanol as the alcohol and a carboxylic acid
having from about 6 to about 22 carbon atoms a temperature will be on the order
of about 70° to about 100° C. However, temperatures on the order at about 40° to
about 120° C. and more preferably 60° to about 80° C. will be employed. The
specific temperature employed will be determined however by the specific alcohol
employed and specific carboxylic acid to be esterified. In the laboratory reflux
95
periods of about 1 to 2 hours were sufficient to provide yields of methyl
isooctanoate in the methanol esterification of isooctanoic acid employing about
1.5 to about 2 moles of methanol per mole of isooctanoic acid which provided the
ester of greater than 99% purity. In contrast, in reactions not using an excess
of sulfuric acid (only a catalytic amount) time periods of reflux of about 10 hours
or more were required to provide about an 80% yield of ester of lower purity even
with a seven molar excess of methanol. Again, the reaction period will depend on
the specific alcohol employed and specific acid to be esterified. Generally reaction
periods will not need to exceed about 4 hours and the reaction will be complete
(about 90% yield) usually within 1 to about 3 hours employing the preferred levels
of carboxylic acid, alcohol and sulfuric acid. After completion of
the esterification the sulfuric acid layer is removed and any unesterified acid is
removed as the sodium salt by an alkaline aqueous wash. The ester may be dried
by azeotropic distillation with an aliphatic hydrocarbon solvent such as heptane.
The unreacted carboxylic acid in the aqueous alkaline wash can be recovered by
acidification with an acid, preferably spent sulfuric acid, from
the esterification step.
It has now been discovered that the use of a significant excess
of sulfuric acid in the reaction provides unexpectedly high yields of the desired
ester and the ester is of high purity. The sulfuric acid not only acts as a catalyst for
the reaction but the excess acid further unites with, dessicates, removes or
96
immobilizes the water of reaction by forming a second phase, resulting in an
increased yield of the ester, in excess of 90% of the acid being converted to the
ester. The ester further is of high purity of about 99%. While the present invention
is applicable to any esterification of a carboxylic acid with an alcohol, it is of
particular interest to the esterification of longer chain carboxylic acids such as the
branched acids having about 6 to about 22 carbon atoms with lower alkyl alcohols
containing from 1 to about 4 carbon atoms, which esters may be subsequently
converted to diketones which are useful as metal extractants.
97
D. DESIGN AND EQUIPMENT LITERATURE
• Fixed-Bed Catalytic Reactor
Synthesis of glycerol to acrolein may take place in a fixed bed reactor,
fluidized bed or moving fluidized bed reactor, or in a modular configuration.
Among the following reactors, fixed-bed or packed-bed reactor is the most
appropriate to use.
“A fixed-bed reactor typically is a cylindrical vessel that is uniformly
packed with catalyst pellets. Non-uniform packing of catalyst may cause
channeling that could lead to poor heat transfer, poor conversion, and catalyst
deactivation due to hot spots. The bed is loaded by pouring and manually packing
the catalyst or by sock loading. As discussed earlier, catalysts may be regular or
shaped porous supports, uniformly impregnated with the catalytic ingredient or
containing a thin external shell of catalyst. Catalyst pellet sizes usually are in the
range of 0.1 to 1.0 cm (0.039 to 0.39 in).” (Perry’s Chemical Engineer’s
Handbook 8th Edition)
“Packed-bed reactors are easy to design and operate. The reactor typically
contains a manhole for vessel entry and openings at the top and bottom for
loading and unloading catalyst, respectively. A metal support grid is placed near
the bottom, and screens are placed over the grid to support the catalyst and
prevent the particles from passing through. In some cases, inert ceramic balls are
98
placed above and below the catalyst bed to distribute the feed uniformly and to
prevent the catalyst from passing through, respectively. One has to guard the bed
from sudden pressure surges as they can disturb the packing and cause
maldistribution and bypassing of feed.” (Perry’s Chemical Engineer’s Handbook
8th Edition)
There are two basic types of fixed-bed reactors: those in which the solid is a
reactant and those in which the solid is a catalyst. Many examples of the first type
can be found in the extractive metallurgical industries.
In the chemical process industries, the designer will normally be concerned
with the second type: catalytic reactors. Industrial fixed-bed catalytic reactors
range in size from small tubes, a few centimeters diameter, to large-diameter
packed beds. Fixed-bed reactors are used for gas and gas-liquid reactions. Heat
transfer rates in large-diameter packed beds are poor, and where high heat transfer
rates are required, fluidized beds should be considered.
Fixed-bed reactors for industrial syntheses are generally operated in a
stationary mode over prolonged production runs, and design therefore concentrates
on achieving an optimum stationary operation. According to several experiments
that had been conducted (Deleplanque, J. et al. and US Patent 5264625), most of
them uses vertical fixed-bed reactor.
99
Ullman reported that the “Stability, dynamics, and control of fixed-bed
reactors with strongly exothermic reactions has been studied in great detail since
the early 1970s. The numerous publications could give the impression that this is a
particular critical reactor type with a large potential risk. In fact, the opposite is
true. Compared to a liquid-phase reactor of the same size, a fixed-bed reactor
with a gas-phase reaction contains a mass of reactants several orders of
magnitude smaller. There is therefore no danger of runaway exothermic reaction
due to reactants accumulating in the reactor, especially as the heat capacity of the
catalyst mass additionally damps the uncontrolled temperature rise.”
“Nevertheless, instabilities can arise in fixed-bed reactors, particularly
with strong exothermic reactions, and can lead to excess temperature that can
damage the catalyst and the reactor construction materials.”
“Fixed-bed reactors for industrial syntheses are generally operated over a
long production period with almost constant operating parameters. The task of
process control engineering is simply to keep these parameters optimal. In
contrast, for supply or disposal plants that have several users or suppliers in the
production network, there are frequent changes of feed material and throughput
which require fast, automatic reaction control. Examples are fixed-bed reactors
for synthesis gas production or off-gas treatment.”
US Patent 2010/0204502 A1 “The process according to the invention may
be carried out in the gas phase or in the liquid phase, preferably in the gas phase.
100
When the dehydration reaction is carried out in the gas phase, various process
technologies may be used, namely fixed-bed process, fluidized-bed process or
circulating fluidized-bed process. The dehydration of glycerol may also be carried
out in the liquid phase in a conventional reactor for a liquid phase reaction, but
also in a catalytic distillation type reactor. The contact time is the ratio of the
volume of the catalyst bed to the volume of gaseous reactants conveyed per
second. The average temperature and pressure conditions in a bed may vary
depending on the nature of the catalyst, the nature of the catalyst bed and the size
of the catalyst. It is possible to use, as the support, any material such as silica,
alumina, titanium oxide, silicon carbide, silica/alumina mixture, silicates, borates
or carbonates on condition that these products are stable under the reaction
condition to which the catalyst will be subjected.”
Sabater Prieto Sergio reported that the “The design of the reactor consists
in the determination of the appropriate dimensions to carry out the dehydration of
glycerol in a large scale. In practice, it is necessary to carry out the determination
of the catalytic volume, which will be placed in the reactor.”
“Therefore, it is necessary to know the dimensions of the catalytic fix-bed
for the pilot scale apparatus before the determination of the reactor dimensions. It
is necessary to know the behaviour of the reaction in the lab scale apparatus. In
this way, the glycerol conversion is the main factor, as well as, the glycerol
solution flow.”
101
“By plotting the glycerol conversion versus the ratio, volume of catalyst /
pure glycerol flow, a curve was obtained. At high conversion increases, until it
reaches a 100% conversion.”
“The objective of this curve is to determine the break point, when the
glycerol conversion reaches 100%. At this point of conversion, there is a ratio,
volume of catalyst/glycerol flow (Vcat/Fglycerol). By choosing a certain scale up
factor for the production, which means, a scale factor, for pumped glycerol, the
catalytic volume for the scale up can be calculated. It can be observed that the
break point for the glycerol conversion is found approximately at a Vcat/Fglycerol =
0.5 – 0.6. This is the smallest ratio, or in other words, the highest feed flow for a
constant catalytic bed, which can be used to obtain a 100% glycerol conversion.”
102
• Multitubular Fixed-Bed Catalytic Reactor
Catalytic fixed-bed reactors are the most important type of reactor for the
synthesis of large scale basis chemicals. In these reactors, the reaction take place
in the form of a heterogeneous catalyzed gas reaction on the surface of catalysts
that are arranged as so-called fixed bed in the reactor.
Oxidation process can be operated using a multitubular fixed-bed catalytic
reactor. Advantages of using multitubular fixed-bed are that it is easy scalability
and preferably employed for large-scale industrial implementations. According to
Perry’s Chemical Engineer’s Handbook (R. Perry and D. Green), multitubular
reactor are designed for highly endothermic reactors because it allows uniform
distribution of heat.
“As discussed earlier, heat management is an important issue in the design
of fixed-bed reactors. A series of adiabatic fixed beds with interbed cooling
(heating) may be used. For very highly exothermic (endothermic) reactions, a
multitubular reactor with catalyst packed inside the tubes and cooling (heating)
fluids on the shell side may be used. The tube diameter is typically greater than 8
times the diameter of the pellets (to minimize flow channeling), and the length is
limited by allowable pressure drop. The heat transfer required per volume of
catalyst may impose an upper limit on diameter as well. Multitubular reactors
require special procedures for catalyst loading that charge the same amount of
catalyst to each tube at a definite rate to ensure uniform loading, which in turn
103
ensures uniform flow distribution from the common header. After filling, each tube
is checked for pressure drop. In addition to the high surface area for heat
transfer/volume, the advantage of a multitubular fixed-bed reactor is its easy
scalability. A bench-scale unit can be a full-size single tube, a pilot plant can be
several dozen tubes, and a large-scale commercial reactor can have thousands of
tubes. Disadvantages include high cost and a limit on maximum size (tube length
and diameter, and number of tubes).”
According to Ullmans’ Processes and Process Engineering, the features of
this kind of reactor include temperature control with liquid or gaseous fluid n the
shell side space to improve heat transfer. Also this kind of reactor is practical in
the production of acrylic acid from acrolein. Reactions that are extremely
temperature-sensitive are carried out in reactors in which indirect heat exchange
occurs via a circulating heat transfer medium integrated in the fixed bed. The most
common arrangement is the multitubular fixed-bed reactor, in which the catalyst is
arranged in the tubes and the heat carrier circulates externally around the tubes.
The development of reactors in which the heat exchange surfaces are
integrated in the fixed bed to supply or remove the heat of reaction as close as
possible to the reaction site occurred in parallel with the development of
multistage adiabatic reactors with intermediate heating or cooling.
Ullman reported that the “multitubular fixed-bed reactor constitutes the
oldest and still predominant representative of the class of fixed-bed reactors. Here
104
the catalyst packing is located in the individual tubes of the tube bundle. The heat
transfer medium is circulated around the tube bundle and through an external
heat exchanger, in which the heat of reaction is supplied or removed. Whereas
with endothermic reactions, circulating gas can be used as heat transfer medium,
for strongly exothermic reactions exclusively liquid or boiling heat transfer
medium are used. Only in this way can the catalyst temperature be held in the
narrow temperature range necessary for selective reaction control.”
“Initially, the integration of heat exchange in the fixed bed was utilized to
ensure as isothermal a reaction control as possible, which is why the reactors of
this type are commonly termed “isothermal reactors”. They are characterized by
reaction tubes of 20-80 mm internal diameter and a carefully designed flow
control of the liquid heat transfer medium, with largely constant heat transfer
conditions throughout the tube bundle and maximum temperature changes of the
heat transfer medium in the tube bundle of a few degrees.”
“Because of the small mass storage capacity compared to liquid-phase
reactors, the danger of sudden reaction of accumulated reactants in gas-phase
multitube fixed-bed reactors is low. Leaving out the peculiarities of individual
cases, the following safety risk can be assumed for fixed-bed reactors:”
1. “Leaks which result in the release of large amounts of gas or vapour and
the formation of explosive clouds.
105
2. Leaks resulting in release of large amounts of liquid heat transfer media
(oils, salt melts).
3. Occurrence of ignitable or decomposable gas mixtures in the reactor.
4. Melting of the reactor due to a runaway reaction.”
According to US Patent No. 5264625, the process for the catalytic gas-
phase oxidation of acrolein to acrylic acid is suited using a multitubular fixed-bed
catalytic reactor.
“It is an object of the present invention to provide a process for the
catalytic gas-phase oxidation of acrolein to acrylic acid in a fixed-bed reactor
having contacting tubes, at elevated temperature on catalytically active oxides
with a conversion of acrolein for a single pass of ≥ 95%, which has a reaction
temperature program which is improved with respect to increased selectivity of
formation of acrylic acid”
“We have found that this object is achieved by a process for the catalytic
gas-phase oxidation of acrolein to acrylic acid in a fixed-bed reactor with
contacting tubes, at elevated temperature on catalytically active oxides with a
conversion of acrolein for a single pass of ≥ 95%, wherein the reaction
temperature in the flow direction along the contacting tubes (along the reaction
axis) in a first reaction zone before the starting reaction gases containing the
reactants enter the contacting tubes is from 260° to 300°C until an acrolein
106
conversion of from 20 to 40% is reached, and the reaction temperature is
subsequently reduced by a total of from 5° to 40°C, abruptly or successively in
steps or continuously along the contacting tubes until an acrolein conversion of a
≥ 95% has been reached, with the proviso that the reaction temperature in this
second reaction zone is not lower than 240°C.”
The use of multitubular fixed-bed reactor was also recommended in the
invention entitled “Catalytic Gas-Phase Oxidation of Acrolein to Acrylic Acid”
(US Patent No. 5739391). As stated in their invention,
“We have found theta this object is achieved by a process for the catalytic
gas-phase oxidation of acrolein to acrylic acid in a multiple contact tube fixed-bed
reactor through whose space surrounding the contact tubes only one heat-
exchange medium circuit is passed, at elevated temperature on catalytically active
multi-metal oxides with an acrolein conversion for a single pass of ≥ 95 mole%
and an acrylic formation selectivity of ≥ 90 mol%, which comprises firstly passing
the heat-exchange medium through the multiple contact tube fixed-bed reactor”
107
• Batch Stirred Tank Reactor
The batch reactor has the advantage of small instrumentation cost and
flexibility of operation (may be shut down easily and quickly). It has the
disadvantage of high labor and handling cost, often considerable shutdown time to
empty, clean out, and refill, and poorer quality control of the product. Hence we
may generalize to state that the batch reactor is well suited to produce small
amounts of material and to produce many different products from one piece of
equipment. On the other hand, for the chemical treatment of materials in large
amounts the continuous process is nearly always found to be more economical.
In the batch reactor, the reactants are initially charged into a container, are
well mixed, and are left to react for a certain period. The resultant mixture is then
discharged. This is an unsteady-state operation where composition changes with
time; however, at any instant the composition throughout the reactor is uniform.
“Stirred tanks are common gas-liquid reactors. Reaction requirements
dictate whether the gas and liquid are in a batch or continuous mode. For a
liquid-phase reaction with a long time constant, a batch mode may be used. The
reactor is filled with liquid, and gas is continuously fed into the reactor to
maintain pressure. If by-product gases form, these gases may need to be purged
continuously. If gas solubility is limiting, a higher-purity gas may be continuously
fed (and, if required, recycled). As the liquid residence time decreases, product
108
may be continuously removed as well.” (Perry’s Chemical Engineer’s Handbook
8th Edition)
“A basic stirred tank design is shown in Fig. 19-30. Height/diameter ratio
is H/D = 1 to 3. Heat transfer may be provided through a jacket or internal coils.
Baffles prevent movement of the mass as a whole. A draft tube can enhance
vertical circulation. The vapor space is about 20 percent of the total volume. A
hollow shaft and impeller increase gas circulation by entraining the gas from the
vapor space into the liquid. A splasher can be attached to the shaft at the liquid
surface to improve entrainment of gas. A variety of impellers is in use. The pitched
propeller moves the liquid axially, the flat blade moves it radially, and inclined
blades move it both axially and radially.” (Perry’s Chemical Engineer’s
Handbook 8th Edition)
“Gases may be dispersed in liquids by spargers or nozzles. However, more
intensive dispersion and redispersion are obtained by mechanical agitation. The
gas is typically injected at the point of greatest turbulence near the injector tip.
Agitation also provides the heat transfer and, if needed, keeps catalyst particles
(in a three-phase or slurry reactor) in suspension. Power inputs of 0.6 to 2.0
kW/m3 (3.05 to 10.15 hp/1000 gal) are suitable. Bubble sizes depend on agitation
as well as on the physical properties of the liquid. They tend to be greater than a
minimum size regardless of power input due to coalescence.” (Perry’s Chemical
Engineer’s Handbook 8th Edition)
109
“The reactor may be modeled as two ideal reactors, one for each phase,
with mass transfer between the phases. For example, if the gas has limited
solubility and is sparged through a liquid, the gas may be modeled as a PFR and
the liquid as a CSTR. Mass-transfer coefficients vary, e.g., as the 0.7 exponent on
the power input per unit volume (with the dimensions of the vessel and impeller
and the superficial gas velocity as additional factors).” (Perry’s Chemical
Engineer’s Handbook 8th Edition)
In esterification reactions, a batch reactor equipped with four baffles and a
six-bladed turbine impeller is used according to the Biochemical Engineering
Journal 41 (2008) 87–94 by G.N. Kraai et al.
Batch reactors are used widely in industry at all scales. Batch reactors are
tanks, commonly provided with agitation and a method of heat transfer (usually by
coils or external jacket). This type of reactor is primarily employed for relatively
slow reactions of several hours duration, since the downtime for filling and
emptying large equipment can be significant. Agitation is used to maintain
homogeneity and to improve heat transfer. Since residence time is uniform, a
batch reactor is preferred for better yields and to obtain a higher selectivity.
A “batch” of reactants is introduced into the reactor operated at the desired
conditions until the target conversion is reached. Batch reactors are typically tanks
in which stirring of the reactants is achieved using internal impellers, gas bubbles,
or a pump around loop where a fraction of the reactants is removed and externally
110
recirculated back to the reactor. Temperature is regulated via internal cooling
surfaces (such as coils or tubes), jackets, reflux condensers, or pump-around loop
that passes through an exchanger. Batch processes are suited to small production
rates, to long reaction times, to achieve desired selectivity, and for flexibility in
campaigning different products.
Stirred tank (agitated) reactors consist of a tank fitted with a mechanical
agitator and a cooling jacket or coils. They are operated as batch reactors or
continuously. Several reactors may be used in series. The stirred tank reactor can
be considered the basic chemical reactor, modelling on a large scale the
conventional laboratory flask. Tank sizes range from a few liters to several
thousand liters. They are used for homogeneous and heterogeneous liquid-liquid
and liquid-gas reactions, and for reactions that involve finely suspended solids,
which are held in suspension by the agitation. As the degree of agitation is under
the designer’s control, stirred tank reactors are particularly suitable for reactions
where good mass transfer or heat transfer is required.
When operated as a continuous process, the composition in the reactor is
constant and the same as the product stream, and, except for very rapid reactions,
this will limit the conversion that can be obtained in one stage.
The power requirements for agitation will depend on the degree of agitation
required and will range from about 0.2 kW/m3 for moderate mixing to 2 kW/m3
for intense mixing.
111
According to US Patent 20050107629 and US5324853 – Method for
producing Ethyl Acrylate: In producing ethyl acrylate and for recovering acrylic
acid, ethyl acrylate, ethanol and water from an esterification reactor mixture
containing acrylic acid, ethyl acrylate, ethanol, water, heavy ends, and acid
catalyst; the reaction vessel includes a mixing means which is capable of internally
recirculating at least 2.5 volumes of reactor liquid per minute. The said mixing
means comprising a reactor impeller and at least one baffle disposed about the side
wall of the reaction vessel. The mixing means further comprises a draft tube
disposed about the impeller. This draft tube is formed from either a flat sheet or
heat coils. The reactor impeller is capable of minimizing the internal recirculation
of said reaction mixture such that said reaction mixture from said lower region of
said reaction vessel is recirculated to said upper region before it returns to said
reactor impeller. The reaction vessel has a height to diameter ratio of less than 1.4.
The reactor impeller is either a pitched blade turbine or a hydrofoil type turbine.
Each baffle has a width greater than 1/12th of the diameter of reaction vessel;
whereby each baffle aids in minimizing surface turbulence and vortexing.
112
• Shell and Tube Heat Exchanger
“If larger flows are involved, a shell and tube exchanger is used, which is
the most important type of exchanger in use in the process industries. In these
exchangers the flow is continuous. Many tubes in parallel are used where one
fluid flows inside these tubes. The tubes, are arranged in a bundle, are enclosed in
a single shell and the other fluid flows outside the tubes in the shell side. The
simplest shell and tube exchanger is a 1 shell pass and 1 tube pass, or a 1-1
counterflow exchanger. The cold fluid enters and flows inside through all the
tubes in parallel in one pass. The hot fluid enters at the other end and flows
counterflow across the outside of the tubes. Cross baffles are used so that the fluid
is forced to flow perpendicular across the tube bank rather than parallel with it.
This added turbulence generated by this cross flow increases the shell-side heat-
transfer coefficient.” (Transport Processes and Unit Operations by C. Geankoplis,
3rd edition)
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Shown above is a bundle of small-diameter tubes which are arranged
parallel to each other and reside inside a much larger-diameter tube called the
“shell”. The tubes are all manifold together at other end so that the “tube fluid”
enters the left side and is distributed equally among the tubes. At the right side, the
fluid exits from each tube, is mixed together in a second manifold, and then leaves
as a single stream. The second fluid, called the “shell fluid” flows in the space in
between the outside of tube. Baffle plates inside the shell force the shell fluid to
flow across the tubes repeatedly as the fluid moves along the length of the shell.
The shell and tube exchanger is by far the most common type of heat
transfer equipment used in the chemical and allied industries. The advantages of
this type are as follows:
1. The configuration gives a large surface area in a small volume;
2. Good mechanical layout: a good shape for pressure operation;
3. Uses well-established fabrication techniques;
4. Can be constructed from a wide range of materials;
5. Easily cleaned;
6. Well-established design procedures.
Essentially, a shell and tube exchanger consists of a bundle of tubes
enclosed in a cylindrical shell. The ends of the tubes are fitted into tube sheets,
which separate the shell-side and tube-side fluids. Baffles are provided in the shell
to direct the fluid flow and support the tubes.
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The bundle of tubes in a shell and tube heat exchanger can be stacked in
one of the two different ways
The use of triangular pitch allows the tubes to be more tightly packed -
more tubes and therefore more area per unit volume of shell. This makes the shell
cheaper. On the other hand, the square pitch has the advantage that it is easier to
clean.
As described in the chapter 15: Heat-Exchange Equipment of Unit
Operations of Chemical Engineering, 6th ed. by McCabe W. et al.
“In an exchanger, the shell-side and tube-side heat transfer coefficients are
of comparable importance, and both must be large if a satisfactory overall
coefficient is to be attained. The velocity and turbulence of the shell-side liquid are
as important as those of the tube-side fluid. To promote crossflow and raise the
average velocity of the shell-side fluid, baffles are installed in the shell. In
construction, common practice is to cut away a segment having a height equal to
one-fourth the inside diameter of the shell. Such baffles are called 25 percent
baffles. The baffles are perforated to receive the tubes. To minimize leakage, the
clearances between baffles and shell and tubes should be small. The baffles are
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supported by one or more guide rods, which are fastened between the tube sheets
by setscrews. To fix the baffles in place, short sections of tube are slipped over the
rod between the baffles. In assembling such an exchanger, it is necessary to do the
tube sheets, support rods, spacers, and baffles first and then to install the tubes.
The stuffing box provides for an expansion. This construction is practicable only
for small shells.”
“Shell diameters are standardized. For shells up to and including 23 in. the
diameters are fixed in accordance with the American Society for Testing and
Materials (ASTM) pipe standards. These shells are constructed of rolled plate.”
“The distance between the baffles (center to center) is the baffle pitch, or
baffle spacing. It should not be less than one-fifth the diameter of the shell or more
than the inside diameter of the shell”.
“Tubes are usually attached to the tube sheets by grooving the holes
circumferentially and rolling the tube ends into holes by means of a rotating
tapered mandrel, which stresses the metal of the tube beyond the elastic limit, so
the metal flows into the grooves. In high-pressure exchangers, the tubes are
welded or brazed to the tube sheet after rolling.”
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• Tray Tower Absorption Column
Absorption is a process that refers to the transfer of a gaseous pollutant
from a gas phase to a liquid phase. The absorption process can be categorized as
physical or chemical. Physical absorption occurs when the absorbed compound
dissolves in the liquid; chemical absorption occurs when the absorbed compound
and the liquid react. Liquids commonly used as solvents include water, mineral
oils, non-volatile hydrocarbon oils, and aqueous solutions.
Gas absorbers are most often used to remove soluble inorganic
contaminants from an air stream. The design of an absorber used to reduce
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gaseous pollutants from process exhaust streams involves many factors including
the pollutant collection efficiency, pollutant solubility in the absorbing liquid,
liquid-to-gas ratio, exhaust flow rate, pressure drop, and many construction details
of the absorbers such as packing, plates, liquid distributors, entrainment
separators, and corrosion-resistant materials.
In absorption, mass transfer of the gaseous pollutant into the liquid occurs
as a result of a concentration difference between the liquid and gas phase.
Absorption continues as long as a concentration difference exists where the
gaseous pollutant and liquid are not in equilibrium with each other. The
concentration difference depends on the solubility of the gaseous pollutant in the
liquid. Absorbers remove gaseous pollutants by dissolving them into a liquid
called the absorbent. In designing absorbers, optimum absorption efficiency can be
achieved by doing the following:
• Providing a large interfacial contact area
• Providing for good mixing between the gas and liquid phases
• Allowing sufficient residence, or contact, time between the phases
• Choosing a liquid in which the gaseous pollutant is very soluble
Solubility is a very important factor affecting the amount of a pollutant, or
solute that can be absorbed. Solubility is a function of both the temperature and, to
a lesser extent, the pressure of the system. As temperature increases, the amount of
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gas that can be absorbed by a liquid decreases. From the ideal gas law: as
temperature increases, the volume of a gas also increases; therefore, at the higher
temperatures, less gas is absorbed due its larger volume. Pressure affects the
solubility of a gas in the opposite manner. By increasing the pressure of a system,
the amount of gas absorbed generally increases.
Solubility data are obtained at equilibrium conditions. This involves putting
measured amounts of a gas and a liquid into a closed vessel and allowing it to sit
for a period of time. Eventually, the amount of gas absorbed into the liquid will
equal the amount coming out of the solution. At this point, there is no net transfer
of mass to either phase, and the concentration of the gas in both the gaseous and
liquid phases remains constant. The gas-liquid system is at equilibrium.
Equilibrium conditions are important in operating an absorption tower. If
equilibrium were to be reached in the actual operation of an absorption tower, the
collection efficiency would fall to zero at that point since no net mass transfer
could occur. The equilibrium concentration, therefore, limits the amount of solute
that can be removed by absorption. The most common method of analyzing
solubility data is to use an equilibrium diagram. An equilibrium diagram is a plot
of the mole fraction of solute in the liquid phase, denoted as x, versus the mole
fraction of solute in the gas phase, denoted as y.
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Under certain conditions, Henry’s law may also be used to express
equilibrium solubility of gas-liquid systems. Henry’s law is expressed as:
p = Hx
where: p = partial pressure of solute at equilibrium, Pa
x = mole fraction of solute in the liquid
H = Henry’s law constant, Pa/mole fraction
Henry’s law can be written in a more useful form bt dividing both equation
by the total pressure, PT, of the system. The left side of the equation becomes the
partial pressure divided the total pressure, which equals the mole fraction in the
gas phase, y. The equation will now become:
y = H’x
where: y = mole fraction of gas in equilibrium with liquid
H’ = Henry’s law constant, mole fraction in vapour per mole
fraction in liquid
x = mole fraction of the solute in equilibrium
The most widely used model for describing the absorption process is the
two-film, or double-resistance, theory, which was first proposed by Whitman in
1923. The model starts with the three-step mechanism of absorption. From this
mechanism, the rate of mass transfer was shown to depend on the rate of migration
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of a molecule in either the gas or liquid phase. The two-film model starts by
assuming that the gas and liquid phases are in turbulent contact with each other,
separated by an interface area where they meet. This assumption may be correct,
but no mathematical expressions adequately describe the transport of a molecule
through both phases in turbulent motion.
Two-Film Theory
Therefore, the model proposes that a mass-transfer zone exists to include a
small portion (film) of the gas and liquid phases on either side of the interface. The
mass-transfer zone is comprised of two films, a gas film and a liquid film on their
respective sides of the interface. These films are assumed to flow in a laminar, or
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streamline, motion. In laminar flow, molecular motion occurs by diffusion, and
can be categorized by mathematical expressions.
For gas absorption, the two devices most often used are the packed tower
and the plate tower. Both of these devices, if designed and operated properly, can
achieve high collection efficiencies for a wide variety of gases. Other scrubbing
systems can be used for absorption, but are limited to cases where the gases are
highly soluble. For example, spray towers, venturis, and cyclonic scrubbers are
designed assuming the performance is equivalent to one single equilibrium stage
(i.e., NOG = 1) (Perry 1973).
Tray towers and similar devices bring about stepwise contact of the liquid
and the gas and are therefore countercurrent multistage cascades. On each tray of a
sieve-tray tower, for example, the gas and liquid are brought into intimate contact
and separated and the tray thus constitutes a stage. It is convenient to use the
parallel flow as an arbitrary standard for design and for measurement of
performance of actual trays regardless of their method of operation. For this
purpose a theoretical, or ideal, tray is defined as one where the average
composition of all the gases leaving the tray is in equilibrium with the average
composition of all the liquid leaving the tray.
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• Pervaporator
Pervaporation, in its simplest form, is an energy efficient combination of
membrane permeation and evaporation. It's considered an attractive alternative to
other separation methods for a variety of processes. For example, with the low
temperatures and pressures involved in pervaporation, it often has cost and
performance advantages for the separation of constant-boiling azeotropes.
Pervaporation is also used for the dehydration of organic solvents and the removal
of organics from aqueous streams.
In pervaporation, a multi-component liquid stream is passed across a
membrane that preferentially permeates one or more of the components. As the
feed liquid flows across the membrane surface, the preferentially permeated
components pass through the membrane and are removed as a permeate vapor.
Characteristics of the pervaporation process
The separation is carried out by running a feed stream of the liquid mixture
across a separation membrane under pervaporator conditions. By pervaporator
conditions, we mean that the vapor pressure of the component that it is desired to
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separate into the permeate stream is maintained at a lower level on the permeate
side than on the feed side, and the pressure on the permeate side is such that the
permeate is in the gas phase as it emerges from the membrane. The process results,
therefore, in a permeate vapor stream enriched in the desired component and a
residue liquid stream depleted in that component.
In a first aspect, the process is carried out using multiple membrane
modules or elements arranged in series within a single tube, so that the residue
stream exiting the first module in the series forms the feed to the second module,
and so on, until the final or product residue stream is withdrawn from the last
module in the series.
To maintain adequate transmembrane flux, the feed solution under
treatment is heated within the tube as it passes from one module to the next. This
interstage heating or reheating is achieved by blocking the straight flow path from
the residue end of one module to the feed end of the next, and by heating the
outside surface of the tube. Instead of passing directly to the inlet of the next
module, the feed is directed in a flow path in the annular space between the inside
wall or surface of the tube and the outer casing or surface of the membrane
module that it has just exited. By forcing the stream to flow at least partially back
along the outside of the module, it is brought into heat exchanging contact with the
inside surface of the tube.
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Simplified Pervaporation Process
The process divides the feed stream into a treated residue stream and a
permeate stream, either or both of which may be desired products of the process.
For example, if the feed solution is a dilute solution of ethanol in water, the
process of the invention may be used to form a more concentrated ethanol product
as the permeate stream. Likewise, if the feed solution is ethanol containing just a
few percent of water, the process of the invention may be used to dehydrate the
ethanol, forming a purified ethanol product as the residue stream.
The membrane modules or elements are housed in a tube. The tube serves
to house and support the membrane elements and provide a directed fluid flow. In
addition, the tube conducts heat to warm the feed solution as it passes along the
train of modules, and may provide a pressure-withstanding function if the pressure
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conditions under which the separation process is carried out are substantially
different from the pressure outside the tube.
The outside of the tube may be heated in any appropriate manner.
Preferably, low grade steam is used if available.
The membrane used to perform the separation may be any type of
membrane capable of performing an appropriate separation under
pervaporation conditions. Suitable membranes include polymeric membranes,
inorganic membranes, such as ceramic membranes, and membranes containing
inorganic particles embedded in a polymeric matrix. For example, if the feed
solution is to be dehydrated, a hydrophilic membrane, such as a polyvinyl alcohol
membrane, may be used. If the feed solution is a mixture of olefins and paraffins,
a hydrophobic membrane, such as a fluorinated polyimide membrane, may be
used.
The membranes and modules may take any convenient cylindrical form,
such as flat sheets wound into spiral-wound modules, potted hollow fibers or
tubular membranes that will fit into the tube so as to leave an annular space
between the outer longitudinal surface of a membrane module and the inside
surface of the tube. The configuration of the process and apparatus of the
invention is not suitable for plate-and-frame modules, as these are usually
assembled in stacks, not housed in tubes or cylindrical pressure vessels.
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The series includes at least two modules, and will typically include three,
four, five or six modules mounted end to end in the tube. The modules are
connected as described above such that a feed stream under treatment may enter
the feed end of the first module, flow through the modules in turn and exit as a
final residue stream from the residue end of the last module. The modules are also
connected by a permeate pipe or pipes, through which the collected permeate
stream from the series can flow.
The driving force for transmembrane permeation is the difference between
the vapor pressure of the feed liquid and the vapor pressure on the permeate side.
This pressure difference is generated at least in part by operating with the feed
liquid at above ambient temperature, usually above 30° C., and typically in the
range 30-120° C. Optionally, the permeate side may also be maintained under
vacuum to increase the driving force.
To heat the feed solution as it passes along the chain of modules, the feed
solution is prevented from flowing in a straight line immediately from the residue
end of one module to the feed of the next. Instead, the feed solution exiting the
residue end of a module is directed at least partially back along the outside of the
module it has just exited, into a reheating space or zone between the outer
longitudinal surface of that module and the inside surface of the tube. The reheated
residue solution is then directed out of the reheating space to the feed inlet end of
the next module.
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Any solution that may be treated by pervaporation may be treated by the
process of the invention. Most commonly, the liquid to be treated will be a
solution of one or more organic components in water, or of water in an organic
solvent or solvent mixture, but solutions containing only organic or only inorganic
components may also be treated. Separation of aromatics from paraffins in an oil
refinery, removal of organic sulfur compounds from hydrocarbon mixtures,
dehydration of bioethanol, recovery of ethanol from fermentation broth, and
removal of volatile organic compounds (VOCs) from wastewater are typical
representative examples of separations in which the process of the invention can
be used to advantage.
The separation is carried out by running a feed stream of the liquid mixture
across a separation membrane under pervaporation conditions.
By pervaporation conditions, we mean that the vapor pressure of the component
that it is desired to separate into the permeate stream is maintained at a lower level
on the permeate side than on the feed side, and the pressure on the permeate side is
such that permeate is in the gas phase as it emerges from the membrane. The
process results, therefore, in a permeate vapor stream enriched in the desired
component or components and a residue liquid stream depleted in that component
or components.
Alternatively, the design can be simplified by permanently welding
end 203 to the body of the vessel or manufacturing as a unitary part of the body of
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the vessel. The modules must then be loaded or unloaded from one end only, but
the manufacturing cost of the vessel may be reduced.
The tube or housing may be made of any convenient material. Housings are
usually made of metal, conforming to appropriate codes for the operating
conditions to which they are to be exposed. Pervaporation processes are not
usually operated at feed pressures substantially different from atmospheric,
although they may be operated at high temperatures, above 100° C. In the case that
the feed is introduced at ambient pressure, and 40° C., for example, a housing
made from a plastic may suffice, so long as the material has adequate thermal
conductivity. In the case that the feed is under high hydraulic pressure, or very hot,
a stainless or carbon steel housing, for example, may be needed. In general, we
prefer to use metal housings.
A feed port, 217, and a residue port, 218, are positioned near the ends of the
housing. One or both of the end plates or heads is fitted with, or adapted to accept,
permeate collection pipe,209, through which treated permeate is removed from the
processing train. Alternatively, a flanged permeate port to which the permeate
pipes are connected could be provided.
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CHAPTER III
PROCESS DESCRIPTION
130
CHAPTER III
PROCESS DESCRIPTION
I. INTRODUCTION
Conversion of glycerol into valuable-added chemicals are appearing in
recent years as a result of glycerol availability since it is the main by-product in
the biodiesel production and in other processes concerning biomass as raw
material. A higher number of applications focus in transforming crude glycerol
into more valuable chemicals since it is a molecule rich in functionalities, with
three -OH groups. Thus, several factors, its low price, availability and its
functionalities, make glycerol very attractive as starting material for many
industrial processes.
“P. Sabatier 1918 has described the catalytic conversion of glycerol to
acrolein. In 1948, H.E. Hoyt et al. have patented a heterogeneous catalyzed
continuous process for the production of acrolein from glycerol. In that patent the
consistence of the catalyst material has been reported as diatomaceous earth
supported ortho-phosphoric acid, which has been mixed with a petroleum oil
fraction with a boiling point of about 300°- 400° C. The acrolein yield is claimed
to be 72.3 %.”
“A manufacturing process of acrolein by dehydration of glycerol in phase
gas, in the presence of solid catalysts having an acidity of Hammett H0 between -9
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and -18 such as sulfated zirconia has been developed. These catalysts deactivate
slowly so as to permit long reaction cycles and low reactor volumes.” (Sergio
Sabater Prieto)
“Acrolein also can be prepared from glycerol using subcritical and
supercritical water as the reaction media. This method has shown a certain
potential for the dehydration of glycerol, although the conversion and acrolein
selectivity achieved are not significant enough for industrial application. The
addition of a mineral acid to the water is necessary to obtain high acrolein yields,
although the presence of an acid intensifies the corrosive effect. Thus, for an
attractive commercial process for the acrolein synthesis from glycerol in the near
future, low corrosive anions stable under this reaction conditions are needed.”
“Dehydration of glycerol has been performed in liquid phase with zeolites;
it was found that acrolein yields were lower in liquid phase than in gas phase. In
this sense, a recent patent claims that glycerol in water can be converted into
acrolein, olefins, and acetaldehyde catalyzed by zeolites in a continuous fluidized-
bed reactor. This reaction system allows better heat and mass transfer than fixed-
bed reactors, along with the possibility of performing continuous regeneration if
needed. The highest yield to acrolein was obtained at 350ºC with a ZSM5 zeolite-
based catalyst.” (Guerrero-Perez et al.)
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Acrylic acid is manufactured from glycerol in two steps via acrolein in a
gas phase using special catalysts.
The first stage is the dehydration of glycerol to acrolein using a tungsten
zirconia catalyst is an endothermic reaction (at about 280°C). In the second stage,
oxidation of acrolein to acrylic acid, the acrolein gas is passed over a molybdenum
vanadium oxide catalyst is a strongly exothermic reaction (at about 300°C).
The crude acrolein coming from the first reactor is cooled to about 100°C.
Acrolein containing impurities will be absorbed in water in a purifying process
before continuing to the second reactor. In the oxidation process, the acrolein is
passed through multi-metal oxides in a multitube fixed-bed reactor at temperature
of about 300°C.
From the published US Patent by Jean-Luc Dubois entitled Method for
Preparing Acrylic Acid from Glycerol, Patent No.: US 2010/0168471 A1:
“Glycerol is produced by the methanolysis of vegetable oils at the same
time as the methyl esters which are employed in particular as motor fuels or fuels
in diesel and home-heating oil. It is a natural product, available in large
quantities, and can be stored and transported without difficulty. It has the
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advantage of being a renewable raw material meeting the criteria associated with
the new concept of “green chemistry”. The development of glycerol has attracted
considerable research, and the preparation of acrylic acid is one of the
alternatives considered.”
“The invention related to a method of preparing acrylic acid from an
aqueous glycerol solution, comprising a first step of dehydration of the glycerol to
acrolein, carried out in the gas phase in the presence of a catalyst and under a
pressure of between 1 and 5 bar, and a second step of oxidation to acrylic acid.”
Acrylic acid is a corrosive chemical that is miscible in water, alcohol, and
esters and polymerizes readily in the presence of oxygen forming acrylic resins.
For this reason, the product is usually stabilized with polymerization inhibitors
such as methyl ethyl hydroquinone (MEHQ).
There are two grades of acrylic acid commercially available:
Technical Grade Acrylic Acid which usually has about 94 percent acrylic
acid content. Technical (also referred to as crude) acrylic acid is suited for the
production of commonly acrylate esters. Major markets for the commodity esters
include surface coatings, adhesives and sealants, textiles, plastic additives, and
paper treatment.
Glacial Grade Acrylic Acid is generally used to designate grades of the acid
with acrylic acid content between 98 to 99.7 percent; although in the literature of
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many companies selling the product, glacial grade is typically listed as having 99.5
to 99.7 percent acrylic acid content. Glacial acrylic acid is suited for the
production of super absorbent polymers (fro disposable diapers), detergents, water
treatment and dispersants.
For esters, whose manufacture is normally integrated with an acrylic acid
plant, the purification step is undertaken after the esterification process. The
technical grade of the acid is therefore not traded. Acrylates are derivatives of
acrylic acid (such as methyl and ethyl acrylate) whose properties have been
sufficiently modified to enable of acrylic acid to be used in different media as
emulsion and solution polymers. As emulsions, these products may be used as
coatings, finishes and binders leading to applications in paints, adhesives, and
polishes with solutions used for industrial coatings. Two-third of the world's
production of acrylic acid is used to produce acrylic esters (acrylates) primarily for
use in emulsions and solution polymers for latex-based paints, coatings, adhesives
and textiles.
According to the Esterification of Acrylic Acid from US Patent No.
3458561, “The invention related to a novel process for esterifying acrylic acid. A
number of processes are known which are directed to the corresponding acylic
acid and an alcohol to the corresponding acrylic ester in the presence of an
esterification catalyst. Esterification of acrylic acid is possible in a liquid as well
135
as in gas phase. Of primary importance as an esterification catalyst is sulphuric
acid. ”
Acrylic esters may be polymerised, catalysed by heat and oxidising agents
in solution or emulsion methods to form long-chain thermoplastic resins. Broadly,
acrylic ester polymers are colourless, insoluble in aliphatic hydrocarbons and
resistant to alkali, mineral oils and water so that with good resistance to
degradation, adhesion and electrical properties, they are widely used.
Surface coatings, such as paints, represent the largest application for acrylic
esters at about 19 per cent of the market. Demand, that was motivated by the
convenience of water-based paints especially the superior acrylic-based emulsions,
is now being driven by regulations and interests to reduce atmospheric release of
volatile organic compounds (VOCs) used as solvents in traditional (alkyd-based)
surface coatings. This sector is growing at 3 to 5 per cent per year with faster
growth for newer more sophisticated applications (such as UV radiation-curable
polymers).
136
137
Preheated Crude Glycerol T = 180-350°C
• Glycerol <60% • Water >40%
T = 180-350°C P = 1-2 bar
III. DETAILED PROCESS DESCRIPTION EQUIPMENT NAME: Preheater
EQUIPMENT CODE: B-1
Preheater is a general term to describe any device designed to heat fluid
before another process with the primary objective of increasing the thermal
efficiency of the process. Also, the unit serves to impart latent heat to a fluid.
Glycerol conversion can be modulated in the gas-phase reaction and it was
found that acrolein yields were higher. The heated crude glycerol will be sent to
dehydration reactor. Heating is conducted to introduce the crude glycerol stream
already in the gaseous phase.
Crude Glycerol • Glycerol <60% • Water >40%
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Prieto included in his study that “when the glycerol solution reaches 200
°C, the mixture is completely evaporated. Between 104 and 200 °C, the system is a
mixture of liquid and vapor” (Prieto, Sergio Sabater. Optimization of the
Dehydration of Glycerol to Acrolein and a Scale up in a Pilot Plant).Crude
glycerol solution is first sent to a preheater before sending to the dehydration
reactor. “The charge sent into the reactor may be preheated to a preheating
temperature of the order of around 180°C to 350°C.” (From US 2010/0204502)
139
T = 250-280°C P = 1-3 bar
EQUIPMENT NAME: Dehydration Reactor
EQUIPMENT CODE: R-1
Preheated crude glycerol is sent to a fixed bed reactor containing tungstated
zirconia, a dehydration catalyst, with temperature ranging from 250-280°C and
pressure of 1-3 bar. The glycerol undergoes dehydration reaction to produce the
acrolein and acetol, which is the major by-product of the reaction. Reaction of the
dehydration of glycerol to acrolein is given below.
Crude Glycerol (from B-1)
T = 180-350°C • Glycerol <60% • Water >40%
Crude Acrolein T = 250-280°C
• Acrolein (30-40%) • Acetol<5% • Water <60% • Inert gases (H2, O2)
140
At temperatures higher than 240 °C, glycerol is extensively converted. The
acrolein selectivity shows a maximum at 280 °C. At lower temperatures the
intermolecular dehydration, yielding oligomers of glycerol, is thermodynamically
favoured over the desired intramolecular dehydration forming acrolein. At
temperatures higher than 280 °C, the formation of CO and CO2 is possible. These
two reasons are responsible for the selectivity decrease of acrolein. (From Ulgen et
al. Conversion of Glycerol to Acrolein in the Presence of WO3/ZrO2 Catalysts)
By S. Prieto in his dissertation entitled “Optimization of the Dehydration of
Glycerol to Acrolein and a Scale up in a Pilot Plant”, he reported that tungsten
zirconia catalysts are the most promising because it offer inherent advantages from
the standpoint of industrial application, such as higher stability under high-
temperature treatments, lower deactivation rates during catalysis, and easier
regeneration.
“An approach for finding an optimum working point can be determined. To
get a complete glycerol conversion it is better to work at high temperatures.
Around 280 °C the acrolein production is the highest. However, at higher
temperatures, close to 300 °C, the formation of acrolein decreases a little, and the
formation of by-products increases with the temperature. Therefore, a
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temperature, around 285 °C will be appropriate to produce the highest amount of
acrolein at a complete glycerol conversion and to minimize the formation of by-
products. The glycerol concentration should be not too high because at high
glycerol concentrations, the glycerol conversion and acrolein selectivity
decreases.”
Formation of acetol with acetone as an intermediate step is also considered
in the dehydration of glycerol to acrolein.
According to the US Patent 5387720, “gas phase reaction is preferable
since it enables a degree of conversion of the glycerol of close to 100% to be
obtained. A proportion of about 10% of the glycerol is converted into acetol,
which is present as the major by-product in the acrolein solution.”
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T = 100-150°C P = 1-2 bar
EQUIPMENT NAME: Heat Exchanger
EQUIPMENT CODE: H-1
The gas stream from the dehydration reactor is sent to a heat exchanger
where it is cooled to a temperature of 100-150°C from a temperature of 250-280
°C before sending the said stream to a condensation unit where water-rich stream
with heavy by-product is removed from the crude acrolein stream.
Based from the invention made by Dubois (US 2010/0168471), “The gas
stream leaving the first reactor is cooled to 151°C in a heat exchanger.”
According to the invention based from the US Patent 5770021, Process and
Apparatus for Purification of a Gas Stream containing Acrolein, “In the first stage
of the process of the invention, the feed gas stream that typically originates from
Crude Acrolein (from R-1)
T = 250-280°C • Acrolein (30-40%) • Acetol<5% • Water <60% • Inert gases (H2, O2)
Cooled Crude Acrolein T = 250-280°C
• Acrolein (30-40%) • Acetol<5% • Water <60% • Inert gases (H2, O2)
143
the gas-phase oxidation of glycerol is preferably cooled from its production
temperature to a temperature ranging from 100 to 200°C and is introduced into
the bottom part of the cooling column”.
144
EQUIPMENT NAME: Absorption Column
EQUIPMENT CODE: A-1
In the first stage of the purification process, the feed gas stream that
typically originates from the gas-phase dehydration of glycerol to acrolein is
preferably cooled from its production temperature to a temperature ranging from
100° to 150°C and is introduced into the bottom part of the cooling column.
T = 50-60°C P = 1-2 bar
Cooled Crude Acrolein (from H-1)
T = 250-280°C • Acrolein (30-40%) • Acetol<5% • Water <60% • Inert gases (H2, O2)
Top Stream T = 50-60°C
• Acrolein (90-95%) • Inert gases (H2, O2) • Water
Bottom Stream • Water >90% • Acetol<10% • Acrolein <1.5%
Absorbing Solvent • Water (100%)
145
Accordingly, the gaseous effluent may be subjected to an absorption
operation and be carried out in an absorption column. The water circulates
countercurrentwise to the effluent with a mass flow rate preferably ranges from
0.005 to 0.05. (US Patent No. 5770021)
“The invention relates to a method for preparing acrylic acid from an
aqueous glycerol solution, comprising a first step of dehydration of the glycerol to
acrolein, in which an intermediate step is implemented, consisting in at least
partly condensing the water and heavy by-product present in the stream issuing
from the first dehydration step. The method according to the invention, even
though it requires an additional unit associated with the intermediate step, has the
advantage of using an economical raw material and of being able to optimize the
two reaction stages separately. The method remains demonstrably economical.”
(US Patent No. 2010/0168471)
Purification of acrolein is described in the US Patent No. 5770021 entitled
“Process and Apparatus for Purification of a Gas Stream Containing Acrolein”.
“The circulation of the gaseous stream in the column countercurrentwise to
a cold liquid results in condensation of the water and other condensable
components that may be present. The condensed liquid which includes acetol,
water and some part of acrolein flows back down under gravity to the bottom of
the column. The gases at the top of the column composed of acrolein, water and
146
non-condensable gases. The temperature of the gases at the top of the column
preferably ranges from 30° to 60°C, and still more preferably from 50° to 60°C.”
“The cooling column preferably operates at a pressure ranging from 105 to
3x105 Pa.”
“The bottom stream generally contains organic acids and preferably less
than 2%, more preferably less than 1.5%, by weight of acrolein and at least 90%
by weight of water.”
147
T = 180-250°C P = 1-2 bar
EQUIPMENT NAME: Preheater
EQUIPMENT CODE: B-2
Stream that exits at the top of the absorption column is sent to a preheater.
This equipment operates at temperature of 180°C to 250°C.
Acrolein from the absorption column is first sent to a preheater before
sending to the oxidation reactor. “The charge sent into the reactor may be
preheated to a preheating temperature of the order of around 180°C to 350°C.”
(From US 2010/0204502)
The acrolein from the absorption column will pass first to a preheater
before entering the oxidation reactor in order to reach the desired temperature
attainable in the reactor. Steam will serve as the heating medium.
Acrolein Stream (from A-1)
T = 50-60°C • Acrolein (90-95%) • Inert gases (H2, O2) • Water
Preheated Acrolein T = 180-250°C
• Acrolein (90-95%) • Inert gases (H2, O2) • Water
148
EQUIPMENT NAME: Oxidation Reactor
EQUIPMENT CODE: R-2
The heated stream mixture from the heat exchanger is then sent to a reactor
for the oxidation process. The oxidation reactor comprises of an oxidation catalyst,
vanadium-molybdenum oxide, at T = 250-300°C and P = 1-5 bar. The acrolein-
rich stream, stripped of the heavy by-products and most of the water, is sent to the
oxidation reactor where acrolein can then be oxidized to acrylic acid.
T = 250-300°C P = 1-5 bar
Preheated Acrolein (from B-2)
T = 180-250°C • Acrolein (90-95%) • Inert gases (H2, O2) • Water
Air
Crude Acrylic Acid T = 250-300°C
• Acrylic Acid (50-55%) • Acrolein <0.10% • Inert gases (N2, H2, O2) • Water <0.80%
149
According to J. Tichy in his work refer to “Oxidation of acrolein to acrylic
acid over vanadium-molybdenum oxide catalysts”, he reported that “oxidation of
acrolein proceeds favourably with a stoichiometric excess of oxygen, and the
reaction temperature should not exceed 573 K or else it will yield an undesirable
radical reaction”. He also believed that among the recommended catalysts, the
most efficient system for the conversion of acrolein to acrylic acid involve oxide
systems based on Mo-V, Mo-Co, V-Sb and heteropolyacids.
US Patent 20100168471 also suggested the catalysts made of formulations
containing Mo and/or V and/or W and/or Cu and/or Sb and/or Fe should be used
in the catalytic reaction.
Conversion of crude glycerol to acrylic acid via acrolein as its intermediate
step is shown in this stoichiometric reactions.
Oxidation reaction from acrolein to acrylic acid.
According from the two inventions (US Patent 5264525 and US Patent
5739391), “A process for the catalytic gas-phase oxidation of acrolein to acrylic
150
acid in a fixed-bed with contacting tubes, at elevated temperature on catalytically
active oxides with a conversion of acrolein for a single pass of ≥ 95%.”
“We have found that this object is highly achieved wherein the reaction
temperature in the flow direction along the contacting tubes (along the reaction
axis) in a first reaction zone before the starting reaction gases containing the
reactants enter the contacting tubes is from 260° to 300°C until a acrolein
conversion of a ≥95% has been reached, with the provision that the reaction
temperature in this secondary reaction zone is not lower than 240°C.”
Based on the US Patent 20100168471, “Oxidation reaction takes place at
temperature of between 200 °C and 350 °C, preferably from 250 °C to 320 °C and
under the pressure of between 1 and 5 bar. The reaction is carried out in the
presence of molecular oxygen which may be in the form of air having a content of
between 3 to 20% by volume, with regard to the incoming stream and optionally in
the presence of inert gases such as N2. The inert gases necessary for the method
may be optionally consist in full or in part of gases obtained at the top of the
absorption column”.
US Patent 5264625 entitled “Catalytic Gas-phase Oxidation of Acrolein to
Acrylic Acid” described the oxidation process is highly exothermic. It is therefore
required to control the reaction temperature in order to obtain a highly selective
conversion of acrolein to acrylic acid.
151
T = 90-100°C P = 1-2 bar
EQUIPMENT NAME: Dehumidifying Condenser
EQUIPMENT CODE: C-1
The gas effluent from the oxidation reactor is first sent to a condenser
where it is cooled to a temperature of 60-100°C from a temperature of 250-300°C.
The crude acrylic acid from the second reactor will pass through a
dehumidifying condenser where acrolein and other inert gases will separate from
the acrylic acid-water mixture. The acrylic acid and water will be condensed and
be sent to the esterification reactor.
Crude Acrylic Acid (from R-2)
T = 250-300°C • Acrylic Acid (50-55%) • Acrolein <0.10% • Inert gases (N2, H2, O2) • Water <0.80%
Condensate T = 100-150°C
• Acrylic Acid (80-85%) • Water (15-20%)
Uncondensed and inert gases • Acrolein <3% • Inert gases (N2, H2, O2)
152
Based from the invention made by Sridhar (US 005463121A), “The gas
stream leaving the reactor is cooled to 60-100°C in a heat exchanger before
undergo the pervaporation process.”
153
EQUIPMENT NAME: Esterification Reactor
EQUIPMENT CODE: R-3
Acrylic acid free of inert gases from the condenser and ethanol are fed to
the esterification reactor. “The minimum temperature at which the esterification is
achieved depends upon the boiling point of the formed acrylic acid ester and
water. In general, a reboiler temperature between 70 to 180°C with pressure of
760 mm of mercury, is employed. The novel esterification can be carried out by
T = 70-180 °C P = 0.3-0.6 bar
Ethanol
Crude Ethyl Acrylate T = 70-180°C
• Ethyl Acrylate (70-80%) • Water (20-25%) • Acrylic Acid <1.0% • Ethanol <0.50%
Condensate (from C-1)
T = 90-100°C • Acrylic Acid (80-85%) • Water (15-20%)
Sulfuric Acid Solution (Catalyst)
154
continuously introducing about equimolar amount of acrylic acid and alcohol in
the reboiler zone or “sump” of a reactor.”(US Patent No. 3458561)
The recommended catalyst in the reaction is Sulfuric Acid. “A number of
processes are known which are directed to the conversion of acrylic acid and an
alcohol to the corresponding acrylic ester in the presence of an esterification
catalyst. Considering the esterification speed and conversion and avoiding at the
same time the formation of undesirable side reactants, the best results are
obtained when using in the reboiler, from 10 to 25% by weight of sulfuric
acid.”(US Patent No. 3458561)
The reaction of acrylic acid and alcohol is as follows:
“Reacting the acrylic acid and ethanol to yield ethyl acrylate in a
conversion of at least 90% on acrylic acid, and yielding the esterification reaction
mixture comprising ethyl acrylate, acrylic acid, ethanol and water.”(US Patent
No. 20050107629)
155
T = 80-100°C P = 1-2 bar
EQUIPMENT NAME: Heat Exchanger
EQUIPMENT CODE: H-2
The gas effluent from the esterification reactor is first sent to a heat
exchanger where it is cooled to a temperature of 80-100°C from a temperature of
70-180°C.
The mixture of ethyl acrylate, water, acrylic acid and ethanol from the third
reactor reactor will pass counter-currently to the heat exchanger before entering
the ethyl acrylate purification process. Water will serve as the cooling medium.
Based from the invention made byAbdullah (EP 2 325 214 A1), “The step
of pervaporation is carried out at a temperature in the range of about 30°C to
about 100°C.”
Crude Ethyl Acrylate (from R-3)
T = 70-180°C • Ethyl Acrylate (70-80%) • Water (20-25%) • Acrylic Acid <1.0% • Ethanol <0.50%
Cooled Crude Ethyl Acrylate T = 80-100°C
• Ethyl Acrylate (70-80%) • Water (20-25%) • Acrylic Acid <1.00% • Ethanol <0.50%
156
EQUIPMENT NAME: Pervaporator
EQUIPMENT CODE: PV-1
This unit will separate water from the crude ethyl acrylate. The water will
pass through the membrane inside the unit and be separated leaving the ethyl
acrylate, ethanol and acrylic acid in the retained material stream. Pervaporation of
water will operate at 60-100 °C and atmospheric pressure.
T = 60-100°C P = 1-2 bar
Permeate • Water
Retained Material Stream T = 60-100°C
• Ethyl Acrylate (90-99%) • Acrylic Acid <1.0% • Ethanol <0.50%
Cooled Crude Ethyl Acrylate
(from H-2) T = 80-100°C
• Ethyl Acrylate (70-80%) • Water (20-25%) • Acrylic Acid <1.0% • Ethanol <0.50%
157
“Solvent dehydration is the most common application of pervaporation.
Transport rates of components through the membrane mixtures of components
with close boiling point and azeotropic mixture can be effectively separated.” (W.
Kujawski, Polish Journal of Environmental Studies Vol.9, No.1 (2000)).
The product from the third heat exchanger is sent to a pervaporator. Water
scrubbed, ethyl acrylate, acrylic acid, and ethanol goes to the bottom of the
column. Based from Polish Journal of Environmental Studies Vol.9, No.1 of W.
Kujawski, “Water is continuously extracted in a side pervaporation from the
mixture containing ester, acid and alcohol.”
According to the patent invented by Abdullah (EP 2 325 214 A1), “The
purification process allows for the production of ethyl acrylate at controlled
composition (0-99 mol-%)”
158
T = 10-15°C P = 1-2 bar
EQUIPMENT NAME: Condenser
EQUIPMENT CODE: C-2
The product from the pervaporator is sent to a condenser where it is cooled
to a temperature of 10-15°C from a temperature of 60-100°C until it reaches its
liquid state. The final product composes of ethyl acrylate with 90-99% purity.
Impurities present in the product are acrylic acid and ethanol.
Component Mole % Mass %
Ethyl Acrylate 98% 99%
Acrylic Acid 1% 0.60%
Ethanol 1% 0.40%
Retained Material Stream (from PV-1)
T = 60-100°C • Ethyl Acrylate (90-99%) • Acrylic Acid <1.0% • Ethanol <0.50% Ethyl Acrylate (Product)
T = 10-15°C • Ethyl Acrylate (90-99%) • Acrylic Acid <1.0% • Ethanol <0.50%
159
CHAPTER IV
PLANT CAPACITY
DETERMINATION
160
CHAPTER IV
PLANT CAPACITY DETERMINATION
I. INTRODUCTION
Acrylic acid has served, for more than 30 years, as an essential building
block in the production of some of our most commonly used industrial and
consumer products. Approximately two-thirds of the acrylic acid manufactured is
used to produce acrylic esters - methyl acrylates, butyl acrylates, ethyl acrylates,
and 2-ethylhexyl acrylates - which, when polymerized are ingredients in paints,
coatings, textiles, adhesives, plastics, and many other applications. The remaining
one-third of the acrylic acid is used to produce polyacrylic acid, or crosslinked
polyacrylic acid compounds, which have been successfully, used in the
manufacture of hygienic products, detergents, and wastewater treatment
chemicals.
The largest application for acrylates esters is the production of surface
coatings (48%), followed by adhesives and sealants (21%), plastic additives and
comonomers (12%), paper coatings, and textiles and surface coatings account for
55% of acrylates ester consumption. Acrylic acid and esters are perhaps the most
versatile series of monomers for providing performance characteristics to
thousands of polymer formulations.
161
Incorporation of varying percentages of acrylates monomers permits the
production of thousands of formulations for latex and solution copolymers,
copolymer plastics and cross-linkable polymer systems. Their performance
characteristics—which impart varying degrees of tackiness, durability, hardness
and glass transition temperatures—promote consumption in many end-use
applications.
The world acrylic acid business is characterized by the involvement of a
relatively few major players who have both globalized and set up a range of
strategic alliances, joint ventures and new integrated companies. According to the
leading suppliers of acrylic acid, the annual demand growth will stay at the level
of 5% in the coming years.
Glacial acrylic acid is used in the manufacture of super absorbing polymers
(SAP), which account for 32% of the global demand for acrylic acid. They predict
162
the following demand growth figures for various segments of acrylic acid
consumption: 3.6% per year for acrylates and 5% per year for super absorbent.
The global market is set to continue to grow in excess of 3%/year, pulled by Asia,
China, and India in particular. Exports of acrylic monomers from the US will
slow, as foreign additions to capacity come online, particularly in the Asia/Pacific
region. In spite of the recent economic woes of that region (which have caused the
delay or cancellation of some projects), capacity is expected to increase
significantly, eroding export markets for US producers.
The largest volume application for acrylics will continue to be in the
manufacture of paints and coatings. Acrylic monomers (both acrylate and
methacrylate types) are widely used as the base resin in coatings due to their
compatibility in reformulated products. The bulk of demand is concentrated in
architectural coatings, where product reformulation has nearly reached saturation
levels. Growth will therefore be greater in industrial and specialty coatings, an
area in which reformulation has lagged due to higher performance requirements.
Ethyl acrylate is used to form paint coatings that are resistant to water,
sunshine, and weather. These coatings retain flexibility even at low temperatures.
EA is also used in industrial finishes and coatings for cans and coils. Fabrics gain
texture and durability when ethyl acrylate is added during their manufacture. Ethyl
acrylate also imparts dirt resistance, improves abrasion, and binds pigments to
fabric. Paper is coated with ethyl acrylate to make it water-resistant. Magazines,
163
books, business paper, frozen food packaging, and folding boxboards have such
coatings, making them resistant to water, grease, and oil. Ethyl acrylate is also
used in adhesives for envelopes, labels, and decals. Caulk, glazing, and various
sealants also contain Ethyl acrylate. Ethyl acrylate is also used as a fragrance
additive in various soaps, detergents, creams, lotions, perfumes, and as a synthetic
fruit essence. Ethyl acrylate is also found in such household items as nail mending
kits and in medical items that assist with the binding of tissues, sealing wounds,
and ileostomy appliances.
164
II. SUPPLY AND DEMAND ANALYSIS
A. INTRODUCTION
Demand has increased for acrylic acid derivatives, specifically ethyl
acrylates used in the production of surface coatings. Still, the growth is being
limited by the current global inventory of crude acrylic acid. Due to growing
demand for acrylic acid derivatives led by SAPs, many of the major producers
have responded by expanding plants and building new production facilities at key
sites throughout the world.
The table below shows the percentage use of Ethyl Acrylate in surface
coatings, adhesives and sealants, plastic additives, paper coatings, and textiles.
Application % Consumption
Surface coatings 48
Adhesives and sealants 21
Plastic additives 12
Paper coatings, and textiles 19
Total 100
Table 4.1. Percent Consumption of Ethyl Acrylate
165
B. DEMAND ANALYSIS
In the Philippines, large percentage of ethyl acrylate is use in paint industry
particularly in the manufacture of water-based latex paints.
Acrylic acid and esters are perhaps the most versatile series of monomers
for providing performance characteristics to thousands of polymer formulations.
Incorporation of varying percentages of acrylates monomers permits the
production of thousands of formulations for latex and solution copolymers,
copolymer plastics and cross-linkable polymer systems.
The tables below show the plant capacity of some paint industries that uses
ethyl acrylate and the percent composition of paint.
Company Annual capacity, tons/yr
Nippon Paint Philippines, Inc.
(Cabuyao, Laguna) 30,000
Boysen Paint
(Trece Martires, Cavite) 818,776
Total 848,776
Table 4.2. Plant Capacity of Some Paint industries in the Philippines that uses Ethyl Acrylate
166
Paints are used to protect metals, timber, or plastered surfaces from the
corrosive effects of weather, heat, moisture or gases etc and to improve their
appearance.
The binder, or resin, is the actual film forming component of paint. It
imparts adhesion, binds the pigments together, and strongly influences such
properties as gloss potential, exterior durability, flexibility, and toughness. Binders
include synthetic or natural resins such as acrylics, polyurethanes, polyesters,
melamine resins, epoxy, or oils.
Components Percent by weight
Binder (Ethyl acrylate) 21
Pigment (coloring) 5
Extender (Calcium carbonate) 13
Dispersant 2
Rheology Modifier 1
Thickener 3
Auxiliary binder 3
Water 52
Total 100
Table 4.3. Percent Composition of Paint
167
C. SUPPLY ANALYSIS
There is no industry that produces Ethyl Acrylate in the Philippines. The
succeeding data is the importation of Ethyl Acrylate in the Philippines from year
2004 to 2008 acquired from the National Statistics Office of the Philippines.
YEAR
COUNTRIES
2005 2006 2007 2008
China,
People's Rep. Of
12,630 3,004 204,234 49,296
Indonesia
(Includes West Irian)
566,880 248,345 417,487 643,563
Japan
(Excludes Okinawa)
143,065 106,540 738,500 235,582
Korea,
Rep. of (South)
1,547,700 1,631,096 1,400,716 1,026,230
Malaysia
(Federation of Malaya)
1,572,684 1,913,767 7,425,932 6,851,514
Singapore 1,373,245 1,674,298 1,457,535 4,571,053
Table 4.4. Importation Data Ethyl Acrylate (in kilograms)
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South Africa,
Rep. of
326,445 650,925 23,550 -
United States
of America
3,763,022 1,799,191 220 369,128
TOTAL 9,307,671 8,027,166 11,668,174 13,746,366
The table shows the top five countries that export Ethyl Acrylate in the
Philippines; United States of America, Singapore, Korea, Indonesia and Malaysia.
The average annual importation of Ethyl Acrylate amounts to 10,687,344 kg or
about 10,687.344 MT. The average annual percentage increase in importation
between 2005 and 2008 is 16.14%.
169
III. MAJOR RAW MATERIAL AVAILABILITY
The raw material to be used for the production of Ethyl Acrylate is crude
glycerol. Glycerol is known to be one of the by-products in the production of
Biodiesel. Every 1000 kg of biodiesel about 100 kg of raw glycerol are obtained.
The table below shows the annual production of Biodiesel based on the top three
Biodiesel-producing plants in the country.
Biodiesel Producers Annual Capacity,
L/yr
Glycerol Production,
MT/yr
(By-product)
Chemrez Technology Inc. 60,000,000 5,280
Senbel Fine Chemicals Inc. 36,000,000 3,168
Romtron Philippines 300,000 26.4
Mt. Holy Coco 4,000,000 352
TOTAL 100,300,000 8,826.40
*density of biodiesel ~ 0.88 kg/L
The total annual production of biodiesel is about 100,300,000 litres. Thus,
the annual crude glycerol production, based on the biodiesel production in the
country, is about 8,826.4 MT.
Table 4.5. Total Annual Coco-Biodiesel Production of the Biggest Biodiesel Plant in the Philippines
170
IV. CONCLUSION
To estimate the amount of Ethyl Acrylate produced using glycerol as the
major raw material, the equation below is used.
Molar mass of glycerol = 92.08 kg/kmol
Molar mass of ethyl acrylate = 100.08 kg/kmol
From Chapter 3:
Conversion of glycerol to acrolein = 90%
Conversion of acrolein to acrylic acid = 98%
Conversion of acrylic acid to ethyl acrylate = 99%
171
From Table 4.2: Annual Capacity of Nippon Paint Phil. Inc. = 30,000 tons/yr
From Table 4.3: Percent Composition of Ethyl Acrylate in Paint = 21%
Annual Demand of Ethyl Acrylate
Calculation of Glycerol needed based on the Ethyl Acrylate (EA) Demand:
The basis in determining the plant capacity of the proposed plant is based
on the annual Ethyl Acrylate demand of Nippon Plant Philippines, Inc. The
availability of the major raw material, glycerol is based on the annual production
of biodiesel in the Philippines. The annual demand of Ethyl Acrylate of Nippon
Paint amounts to about 6,300 tons. Based from the calculated amount of glycerol
above, we have concluded to source out from the two of the largest biodiesel
producers namely Chemrez Technology Inc. and Senbel Fine Chemicals Inc., with
an amount of 5,280 MT and 3,168 MT, respectively.
172
Since the availability of the major raw material from the two biodiesel
companies (8,448 MT glycerol) exceeds the amount needed (6,100 MT glycerol),
we aim to manufacture 5,700 MT annually of ethyl acrylate to supply the demand
of the local paint industry. The plant will operate at 24 hours daily in 300 days per
year.
173
CHAPTER V
MASS AND ENERGY
BALANCE
174
CHAPTER V
MASS AND ENERGY BALANCE
I. INTRODUCTION
In the successful operation of a manufacturing plant, the amount of product
to be produced in a certain amount of raw materials is needed in the study to
determine the feasibility of the project. Thus the material balance established
together with amount of energy consumption per amount of product or raw
materials will determine the cost of product.
All material balances are based upon the law of conservation of mass. By
this law, every unit of mass entering a system or process must subsequently leave
as mass. However, chemical and/or physical changes may have occurred in the
system so that the form of feed and products may be expected to change.
The law of entering equal to leaving generally applies on the material as
well as the energy balance. The amount of raw material supply to the reactor will
be equal to the product produce in each reactor, thus the balance between the
products and raw material is established through its chemical reaction.
In every balance, the second law of thermodynamics is applied which states
that the energy cannot be destroyed but can be exchanged, stored and transformed
into its different forms but the total amount do not change. The amount of heat
175
needed, water to be fed in each reactor was determined through energy balance
established by the chemical reaction in each reactor.
176
177
III. SUMMARY OF BASIS, ASSUMPTIONS AND EQUATIONS
A. MASS BALANCE
Glycerol Preheater (B – 1)
- Crude glycerol will be completely evaporated at 280°C.
(Ref:Optimization of the Dehydration of Glycerol to Acrolein and a Scale
up in a Pilot Plant, Sergio SabaterPrieto)
Dehydration Reactor (R – 1)
- 100% glycerol conversion
(Ref: Optimization of the Dehydration of Glycerol to Acrolein and a Scale
up in a Pilot Plant by Sergio SabaterPrieto
Process for Dehydrating Glycerol to Acrolein. United States Patent
Number 2008/0214880 by Dubois J.L. et.al.)
- 90% of glycerol will be dehydrated producing acrolein, the rest is
converted to acetone. All acetone formed will react with water
producing acetol.
(Ref: Process for Dehydrating Glycerol to Acrolein. United States Patent
Number 2008/0214880 by Duboi, J.L. et.al.)
178
Heat Exchanger (H – 1)
- The gaseous products from R-1 are cooled to 150°C.
(Ref: Process for Dehydrating Glycerol to Acrolein. United States Patent
Number 2008/0214880 by Dubois, J.L. et.al.)
Absorption Column (A – 1)
- All inert gases go to the top portion of the column.
- 90% of the entering water vapor is condensed.
- Bottom products consist of 1.5% acrolein.
(Ref: Process and Apparatus for Purification of a Gas Stream Containing
Acrolein. United States Patent Number 5770021 by Hegoet.al.)
Acrolein Preheater (B – 2)
- Preheater operates at temperature of 180°C to 250°C.
(Ref:Process for manufacturing Acrolein from Glycerol US Patent
2010/0204502 by Dubois et..al.)
Oxidation Reactor (R - 2)
- 98% of acrolein fed is converted to acrylic acid.
- All O2 from air will be consumed.
179
- Oxygen from feed will serve as the excess O2.
- Mass ratio of catalyst to acrolein is about 1:50.
(Ref: Catalytic Gas-phase Oxidation of Acrolein to Acrylic Acid. United
States Patent Number 5264625 by Hammon, U. et. al.)
Dehumidifying Condenser (C – 1)
- The gaseous products from R-2 are cooled to 90°C. All acrylic acid and
water are condensed.
Esterification Reactor (R – 3)
- 99% of acrylic acid fed is converted to ethyl acrylate.
(Ref: Method for Producing Ethyl Acrylate Patent No. 20050107629A1 by
Hershberger et. al.)
- Equimolar amounts of acrylic acid and alcohol is fed in the reactor.
- 36 N H2SO4 is added to make a concentration of 18% H2SO4 in the
reactor feed.
(Ref: Esterification of Acrylic Acid Patent No. 3458561 by
Kautteret.al.)
180
Heat Exchanger (H – 2)
- The crude ethyl acrylate from R-3 is cooled to 100°C.
(Ref: Esterification of Acrylic Acid Patent No. 3458561 by
Kautteret.al.
Synthesis of acrylic or methacrylic acid/acrylate or methacrylate
ester polymers using pervaporation, Patent No. 2 325 214 A1 by
SaadAIArifi, Abdullah)
Pervaporator (PV – 1)
- Ethyl acrylate content in the retentate is >98 mol%.
(Ref: Synthesis of acrylic or methacrylic acid/acrylate or methacrylate
ester polymers using pervaporation, Patent No. 2 325 214 A1 by
SaadAIArifi, Abdullah)
- Water is continuously extracted from the mixture containing ester, acid
and alcohol.
(Ref: Polish Journal of Environmental Studies Vol.9, No.1 by W. Kujawski)
181
Condenser (C – 2)
- The retentate from PV-1 is cooled to 15°C. Ethyl acrylate is in liquid
phase at 15°C and 1 atm.
(Ref: Ethyl acrylate MSDS, www.cameochemicals.com)
182
B. ENERGY BALANCE
Constants Used In Energy Balance
Code Equipment Constants
B – 1 Glycerol Preheater
From General Chemistry, 7th Edition, Kenneth Whitten et al. (2004):
From Standard Thermodynamic Properties of Chemical Substances (2000):
From Steam Table:
H – 1 Heat Exchanger
From General Chemistry, 7th Edition, Kenneth Whitten et al. (2004):
From Acrolein MSDS (Cameo Chemicals):
From (http://www.chemeo.com/cid/34-484-7):
From Unit Operations in Chemical Engineering, 7th Edition, Warren McCabe et al. (2004):
183
B - 2
Acrolein Preheater
From General Chemistry, 7th Edition, Kenneth Whitten et al. (2004):
From Acrolein MSDS (Cameo Chemicals):
From Unit Operations in Chemical Engineering, 7th Edition, Warren McCabe et al. (2004):
From Steam Table:
R - 2
Oxidation Reactor
From General Chemistry, 7th Edition, Kenneth Whitten et al. (2004):
From Acrolein MSDS (Cameo Chemicals):
From Acrylic Acid MSDS (Cameo Chemicals):
From Unit Operations in Chemical Engineering, 7th Edition, Warren McCabe et al. (2004):
From (http://www.chemeo.com/cid/45-811-1):
184
From Optimization of the Dehydration of Glycerol to Acrolein by SabaterPrieto (2007):
C – 1 Dehumidifying Condenser
From Acrolein MSDS (Cameo Chemicals):
From Unit Operations in Chemical Engineering, 7th Edition, Warren McCabe et al. (2004):
From Acrylic Acid MSDS (Cameo Chemicals):
From ChE Handbook, 8th Edition:
From (http://www.sbioinformatics.com/design_thesis/Acrylic_Acid/Acrylic-2520acid_-2520Properties&uses.pdf):
From General Chemistry, 7th Edition, Kenneth Whitten et al. (2004):
R - 3 Esterification Reactor
From Ethyl Acrylate MSDS (Cameo Chemicals):
From Acrylic Acid MSDS (Cameo Chemicals):
185
From General Chemistry, 7th Edition, Kenneth Whitten et al. (2004):
From Thermodynamic Properties of the Aqueous Sulfuric Acid System to 350 K, Frank Zeiknik:
From (http://www.chemeo.com/cid/45-811-1):
From (http://www.sbioinformatics.com/design_thesis/Acrylic_Acid/Acrylic-2520acid_-2520Properties&uses.pdf):
From Steam Table:
H -2 Heat Exchanger
From Ethyl Acrylate MSDS (Cameo Chemicals):
From Acrylic Acid MSDS (Cameo Chemicals):
From General Chemistry, 7th Edition, Kenneth Whitten et al. (2004):
186
C - 2 Condenser
From Ethyl Acrylate MSDS (Cameo Chemicals):
From Acrylic Acid MSDS (Cameo Chemicals):
From General Chemistry, 7th Edition, Kenneth Whitten et al. (2004):
187
Basis for Calculation:
Plant Capacity: 5,700 MT/yr
Production Rate: 19,000 kg/day
Working days: 300 days/yr
Conversion:
Dehydration Reactor: 90% conversion of glycerol to acrolein
Oxidation Reactor: 98% conversion of acrolein to acrylic acid
Esterification Reactor: 99% conversion of acrylic acid to ethyl acrylate
Assumptions for losses:
Absorption Column: 1.5% acrolein is found at the bottom stream of the unit
Glycerol Requirement
Feed Requirement (60% Crude Glycerol)
188
IV. MASS BALANCE PER EQUIPMENT
GLYCEROL PREHEATER
Assumption:
• Complete evaporation at 250 °C (Prieto, Sergio Sabater,2007) page 81
Input:
Crude Glycerol (Liquid Phase) = 34,000.00 kg
Output:
Crude Glycerol (Gas Phase) = 34,000.00 kg
Crude Glycerol
T = 25°C
Vaporized Crude Glycerol
T = 280 °C
Glycerol 20,400.00 kg Water 13,600.00 kg --------------------- Total 34,000.00 kg
T = 280 °C
B-1
Glycerol 20,400.00 kg Water 13,600.00 kg --------------------- Total 34,000.00 kg
189
DEHYDRATION REACTOR
Input:
Vaporized Crude Glycerol = 34,000.00 kg
Tungstated Zirconia = 8,869.57 kg
-----------------------------
Total Input = 42,869.57 kg
Output:
Crude Acrolein = 34,000.00 kg
Tungstated Zirconia = 8,869.57 kg
-----------------------------
Total Output = 42,869.57 kg
Tungstated Zirconia (Catalyst) Zirconium Oxide 8,044.70 kg Tungsten Oxide 824.87 kg ---------------- 8,869.57 kg
Acrolein 11,173.92 kg Water 20,386.88 kg H2 89.48 kg O2 708.95 kg Acetol 1,640.77 kg --------------------- 34,000.00 kg
Vaporized Crude Glycerol
T = 280 °C
Crude Acrolein
T = 280 °C
T = 280 °C P=1-3 bar
R-1
Glycerol 20,400.00 kg Water 13,600.00 kg --------------------- Total 34,000.00 kg
Tungstated Zirconia 8,869.57 kg
190
Assumptions:
• 100% glycerol conversion.
• Ratio of mass of feed to mass of catalyst is 3.83.
(Sergio SabaterPrieto (2007). Optimization of the Dehydration of Glycerol to Acrolein and a Scale up in a Pilot Plant)
(Dubois, J.L. et al. (2008). Process for Dehydrating Glycerol to Acrolein. United States Patent Number 2008/0214880)
• 90% of glycerol is converted into acrolein, the rest to acetone. All acetone produced will then be converted to acetol.
(Dubois, J.L. et al. (2008). Process for Dehydrating Glycerol to Acrolein. United States Patent Number 2008/0214880)
Data:
Computations:
Feed: Crude Glycerol
Glycerol 20,400.00 kg
Water 13,600.00 kg
---------------------
34,000.00 kg
Component Molecular Weight
Glycerol 92.08
Acetol 74.06
Acrolein 56.04
Water 18.02
H2 2.02
O2 32.00
191
Reactions involved:
Acrolein Production:
Glycerol Acrolein
Acetone Production:
Glycerol Acetone
192
Acetol Production:
Acetone Acetol
Water Balance:
193
Amount of Catalyst:
Components:
Product: Crude Acrolein
Acrolein kg
Water kg
H2 kg
O2 kg
Acetol kg
---------------------
34,000.00 kg
194
HEAT EXCHANGER
Input:
Crude Acrolein = 34,000.00 kg
Output:
Cooled Crude Acrolein = 34,000.00 kg
Acrolein 11,173.92 kg Water 20,386.88 kg H2 89.48 kg O2 708.95 kg Acetol 1,640.77 kg --------------------- 34,000.00 kg
Acrolein 11,173.92 kg Water 20,386.88 kg H2 89.48 kg O2 708.95 kg Acetol 1,640.77 kg --------------------- 34,000.00 kg
Crude Acrolein
T = 280 °C
Cooled Crude Acrolein
T = 150 °C
T = 150 °C
H-1
195
ABSORPTION COLUMN
Input:
Cooled Crude Acrolein = 34,000.00 kg
Water = 16,000.00 kg
---------------------
Total Input = 50,000.00 kg
Output:
Top Stream = 13,742.39 kg
Bottom Stream = 36,257.61 kg
------------------
Total Output = 50,000.00 kg
Absorbing Solvent
T = 30°C
Acrolein 11,173.92 kg Water 20,386.88 kg H2 89.48 kg O2 708.95 kg Acetol 1,640.77 kg --------------------- 34,000.00 kg
Cooled Crude Acrolein
T = 150 °C
Bottom Stream
Water 16,000.00 kg
Top Stream
T = 60 °C
A-1
Acetol 1,640.77 kg Water 34,348.20 kg Acrolein 268.64 kg --------------------- 36,257.61 kg
Acrolein 10,905.28 kg Water 2,038.68 kg H2 89.48 kg O2 708.95 kg
--------------------- 13,742.39 kg
196
Assumptions:
• All inert gases go to the top portion of the column.
• 90% of the entering water vapor is condensed.
• Bottom products consist of 1.5% acrolein.
(Hugo et al. (1998) Process and Apparatus for Purification of a Gas Stream Containing Acrolein)
Data:
Computations:
Feed: Crude Acrolein
Acrolein 11,173.92 kg
Water 20,386.88 kg
H2 89.48 kg
O2 708.95 kg
Acetol 1,640.77 kg
---------------------
34,000.00 kg
Components Molecular Weight Boiling Point (°C)
Acetol 74.06 145
Acrolein 56.04 53
Water 18.02 100
197
Absorbing Solvent:
Henry’s constant for acetol in water is 0.43 atm/mole fraction.
Minimum liquid-to-gas ratio:
Converting to mass units:
198
Bottom Stream:
Solving equations 1 and 2,
Note:*condensed water vapour from the gaseous feed not included
Top Stream:
Acrolein Balance:
199
Top Product:
Acrolein kg
Water kg
H2 kg
O2 kg
---------------------
kg
200
ACROLEIN PREHEATER
Input:
Acrolein Stream = 13,742.39 kg
Output:
Heated Acrolein Stream = 13,742.39 kg
Acrolein Stream
T = 60 °C
Heated Acrolein Stream
T = 200 °C
T = 200 °C
B-2
Acrolein 10,905.28 kg Water 2,038.68 kg H2 89.48 kg O2 708.95 kg
--------------------- 13,742.39 kg
Acrolein 10,905.28 kg Water 2,038.68 kg H2 89.48 kg O2 708.95 kg
--------------------- 13,742.39 kg
201
OXIDATION REACTOR
Input:
Heated Acrolein Stream = 13,742.39 kg
Air Stream = 13,096.23 kg
Vanadium-Molybdenum Oxide = 218.11 kg
---------------------
Total Input = 27,056.73 kg
Output:
Crude Acrylic Acid = 26,838.62 kg
Vanadium-Molybdenum Oxide = 218.11 kg
---------------------
Total Output = 27,056.73 kg
Vanadium-Molybdenum Oxide 218.11 kg
Air Stream T=30 °C
N2 10,044.71 kg O2 3,051.52 kg
-------------------- 13,096.23 kg
Acrolein 10,905.28 kg Water 2,038.68 kg H2 89.48 kg O2 708.95 kg
--------------------- 13,742.39 kg
Acrylic Acid 13,738.70 kg Acrolein 218.10 kg Water 2,038.68 kg N2 10,044.71 kg O2 708.95 kg H2 89.48 kg
-------------------- 26,838.62 kg
Heated Acrolein Stream
T = 200 °C
Crude Acrylic Acid
T = 300 °C
Vanadium-Molybdenum Oxide (Catalyst)
Vanadium (IV) Oxide 34.90 kg Molybdenum Trioxide 183.21 kg ------------- 218.11 kg
T = 300 °C P =1-5 bar
R-2
202
Assumptions:
• 98% of acrolein is converted to acrylic acid.
• Mass ratio of catalyst to acrolein is 1:50.
(Hammon, U. et al. Catalytic Gas-phase Oxidation of Acrolein to Acrylic Acid. United States Patent Number 5264625)
Data:
Computations:
Feed: Acrolein Stream
Acrolein 10,905.28 kg
Water 2,038.68 kg
H2 89.48 kg
O2 708.95 kg
---------------------
13,742.39 kg
Component Molecular Weight
Acrylic Acid 72.04
Acrolein 56.04
Water 18.02
Air 28.84
N2 28.00
O2 32.00
203
Reaction Involved:
Acrylic Acid Production:
Acrolein Acrylic Acid
Amount of Catalyst:
Components:
204
Product: Crude Acrylic Acid
Acrylic Acid kg
Acrolein kg
Water 2,038.68 kg
N2 kg
O2 708.95 kg
H2 89.48 kg
--------------------
26,838.62 kg
205
DEHUMIDIFYING CONDENSER
Input:
Crude Acrylic Acid = 26,838.62 kg
Output:
Uncondensed Vapor and Inert Gases = 11,061.24 kg
Condensed Crude Acrylic Acid = 15,777.38 kg
--------------------
Total Output = 26,838.62 kg
Uncondensed Vapor and Inert Gases
Acrolein 218.10 kg N2 10,044.71 kg O2 708.95 kg H2 89.48 kg ------------------- 11,061.24 kg
Crude Acrylic Acid
T = 300 °C
Condensed Crude Acrylic Acid
T = 90°C
Acrylic Acid 13,738.70 kg Acrolein 218.10 kg Water 2,038.68 kg N2 10,044.71 kg O2 708.95 kg H2 89.48 kg
-------------------- 26,838.62 kg
Acrylic Acid 13,738.70 kg Water 2,038.68 kg --------------------- 15,777.38 kg
T = 90°C
C-1
206
ESTERIFICATION REACTOR
Input:
Acrylic Acid = 13,738.70 kg
Ethanol Stream = 8,784.10 kg
Water = 2,038.68 kg
Sulfuric Acid Solution = 5,067.63 kg
---------------------
Total Input = 29,629.11 kg
Output:
Crude Ethyl Acrylate = 24,561.48 kg
Sulfuric Acid Solution = 5,067.63 kg
---------------------
Total Output = 29,629.11 kg
Crude Ethyl Acrylate
T = 140 °C
Ethanol Stream T = 25 °C
Ethanol 8,784.10 kg
Condensed Crude Acrylic Acid
T = 90°C
Sulfuric Acid Solution (Catalyst)
Sulfuric Acid 4,966.28 kg Water 101.35 kg ------------------------ 5,067.63 kg
Acrylic Acid 13,738.70 kg Water 2,038.68 kg --------------------- 15,777.38 kg
Ethyl Acrylate 18,895.35 kg Acrylic Acid 137.38 kg Water 5,440.91 kg Ethanol 87.84 kg --------------------- 24,561.48 kg
Sulfuric Acid Solution 5,067.63 kg
T = 140 °C
P = 0.3-0.6 bar
R-3
207
Assumptions:
• 99% of acrylic acid fed is converted to ethyl acrylate.
(Hershberger et al., Method for Producing Ethyl Acrylate Patent No. 20050107629A1)
• Equimolar amounts of acrylic acid and alcohol is fed in the reactor.
(Kautter et al., Esterification of Acrylic Acid Patent No. 3458561)
• 36 N H2SO4 is added to make a concentration of 18% H2SO4 in the reactor feed.
Data:
Computations:
Feed:
Component Molecular Weight
Acrylic Acid 72.04
Ethanol 46.06
Ethyl Acrylate 100.08
Water 18.02
208
Reaction involved:
Ethyl Acrylate Production:
Ethanol Acrylic Acid Ethyl Acrylate
Ethanol (EtOH) Balance:
209
Water (H2O) Balance:
Amount of Catalyst Added:
Basis: 1 Liter of Solution
210
Solving equations 1, 2 and 3,
Product: Crude Ethyl Acrylate
Ethyl Acrylate 18,895.35 kg
Acrylic Acid 137.38 kg
Water 5,440.91 kg
Ethanol 87.84 kg
---------------------
24,561.48 kg
211
HEAT EXCHANGER
Input:
Total Input = 24,561.48 kg
Output:
Total Output = 24,561.48 kg
Crude Ethyl Acrylate
T = 140 °C
Cooled Crude Ethyl Acrylate
T = 100 °C
T =100 °C
H-2
Ethyl Acrylate 18,895.35 kg Acrylic Acid 137.38 kg Water 5,440.91 kg Ethanol 87.84 kg --------------------- 24,561.48 kg
Ethyl Acrylate 18,895.35 kg Acrylic Acid 137.38 kg Water 5,440.91 kg Ethanol 87.84 kg --------------------- 24,561.48 kg
212
PERVAPORATOR
Input:
Cooled Crude Ethyl Acrylate = 24,561.48 kg
Output:
Permeate = 5,440.91 kg
Retentate = 19,120.57 kg
------------------------------
Total Output = 24,561.48 kg
Retentate
T = 100 °C
Permeate
T = 100 °C
Cooled Crude Ethyl Acrylate
T = 100 °C
Water 5,440.91 kg
T = 100 °C
PV-1
Ethyl Acrylate 18,895.35 kg Acrylic Acid 137.38 kg Water 5,440.91 kg Ethanol 87.84 kg --------------------- 24,561.48 kg
Ethyl Acrylate 18,895.35 kg Acrylic Acid 137.38 kg Ethanol 87.84 kg --------------------- 19,120.57 kg
213
Assumptions:
• Ethyl acrylate content in the retained material stream is<99% by moles.
(SaadAIArifi, Abdullah, Synthesis of acrylic or methacrylic acid/acrylate or methacrylate ester polymers using pervaporation, Patent No. 2 325 214 A1)
• Water is continuously extracted from the mixture containing ester, acid and alcohol
(W. Kujawski, Polish Journal of Environmental Studies Vol.9, No.1)
Data:
Computations:
Feed:
Ethyl Acrylate (EA) = 18,895.35 kg
Acrylic Acid (AA) = 137.38 kg
Water = 5,440.91 kg
Ethanol (EtOH) = 87.84 kg
Component Molecular Weight
Ethyl Acrylate 100.08
Acrylic Acid 72.04
Ethanol 46.06
214
Top Stream:
Water (H2O) Balance:
Retentate:
Component Mole % Mass %
Ethyl Acrylate 98 99
Acrylic Acid 1 0.60
Ethanol 1 0.40
215
CONDENSER
Input:
Total Input = 19,120.57 kg
Output:
Total Output = 19,120.57 kg
Retentate
T = 100 °C
Ethyl Acrylate (Product)
T = 15 °C
T =15 °C
C-2
Ethyl Acrylate 18,895.35 kg Acrylic Acid 137.38 kg Ethanol 87.84 kg --------------------- 19,120.57 kg
Ethyl Acrylate 18,895.35 kg Acrylic Acid 137.38 kg Ethanol 87.84 kg --------------------- 19,120.57 kg
216
V. ENERGY BALANCE PER EQUIPMENT GLYCEROL PREHEATER
Glycerol:
Crude Glycerol (60% Glycerol Solution)
T = 25°C
Vaporized Crude Glycerol
T = 280 °C
B-1
Steam T = 300°C
217
Water:
218
Steam at 300oC
λ = 1404.60 kJ/kg
Steam Requirement:
219
DEHYDRATION REACTOR
Reactants:
Vaporized Crude Glycerol
COMPONENT MASS (kg) Cp (kJ/kg · K) mCp (kJ/K)
Glycerol 20,400.00 0.92 18,768.00
Water 13,600.00 1.88 25,568.00
∑mCp= 44,336.00
Vaporized Crude Glycerol
T = 280 °C
Crude Acrolein
T = 280 °C
T = 280 °C P=1-3 bar
R-1
220
Reaction:
Acrolein Production:
Glycerol Acrolein
Acetone Production:
Glycerol Acetone
COMPONENT MASS (kg) MW n(kmol) ΔHf
(kJ/kmol)
nΔHf(kJ)
Acrolein 11,173.92 56.04 199.39 -87,800.00 -17,506,602.95
Water 7,186.08 18.02 398.78 -241,800.00 -96,425,890.53
Glycerol 18,360.00 92.08 199.39 -597,000.00 -119,036,924.41
COMPONENT MASS (kg) MW n(kmol) ΔHf
(kJ/kmol)
nΔHf(kJ)
Acetone 1,286.74 58.08 22.15 -216,690.00 -4,800,690.70
Glycerol 2,040.00 92.08 22.15 -597,000.00 -13,226,324.93
221
Acetol Production:
Acetone Acetol
Product:
COMPONENT MASS (kg) MW n(kmol) ΔHf
(kJ/kmol)
nΔHf(kJ)
Acetol 1,640.77 74.06 22.15 -422,650.00 -9,363,662.03
Acetone 1,286.74 58.08 22.15 -216,690.00 -4,800,690.70
Water 399.23 18.02 22.15 -241,800.00 -5,356,993.92
COMPONENT MASS (kg) Cp (kJ/kg · K) mCp (kJ/K)
Acrolein 11,173.92 1.27 14,190.88
Acetol 1,640.77 1.39 2,280.67
Water 20,386.85 1.88 38,327.29
H2 89.48 14.36 1,284.93
O2 708.95 0.92 652.23
∑mCp= 56,736.01
222
223
HEAT EXCHANGER
COMPONENT MASS (kg) Cp (kJ/kg · K) mCp (kJ/K)
Acrolein 11,173.92 1.27 14,190.88
Acetol 1,640.77 1.39 2,280.67
Water 20,386.85 1.88 38,327.29
H2 89.48 14.36 1,284.93
O2 708.95 0.92 652.23
∑mCp= 56,736.01
T = 90 °C
Crude Acrolein
T = 280 °C
Cooled Crude Acrolein
T = 150 °C
Cooling Water T = 28°C
T = 150 °C
H-1
224
Mass of Cooling Water:
225
ACROLEIN PREHEATER
Steam at 300oC
λ = 1,404.60 kJ/kg
COMPONENT MASS (kg) Cp (kJ/kg · K) mCp (kJ/K)
Acrolein 10,905.28 1.27 13,849.70
Water 2,038.69 1.88 3,832.73
H2 89.48 14.36 1,284.93
O2 708.95 0.92 652.23
∑mCp= 19,619.60
Steam T = 300°C
Acrolein Stream
T = 60°C
Heated Acrolein Stream
T = 200°C
T = 200 °C
B-2
226
Steam Requirement:
227
OXIDATION REACTOR
Reactants:
Heated Acrolein
COMPONENT MASS (kg) Cp (kJ/kg · K) mCp (kJ/K)
Acrolein 10,905.28 1.27 13,849.70
Water 2,038.69 1.88 3,832.73
H2 89.48 14.36 1,284.93
O2 708.95 0.92 652.23
∑mCp= 19,619.60
Air Stream T = 30°C
Heated Acrolein Stream
T = 200°C
Crude Acrylic Acid
T = 300°C
T = 280 °C P=1-5 bar
R-2
T = 90°C
Cooling Water T = 28°C
228
Air
Reaction:
Acrylic Acid Production:
Acrolein Acrylic Acid
COMPONENT MASS (kg) MW n(kmol) ΔHf
(kJ/kmol)
nΔHf(kJ)
Acrylic Acid 13,738.70 72.04 190.71 -372,200.00 -70,982,011.94
Acrolein 10,687.17 56.04 190.71 -87,800.00 -16,743,998.29
229
Product:
Mass of Cooling Water:
COMPONENT MASS (kg) Cp (kJ/kg · K) mCp (kJ/K)
Acrylic Acid 13,738.70 1.36 18,684.63
Acrolein 218.10 1.27 276.99
Water 2,038.68 1.88 3,832.72
N2 10,044.71 1.07 10,747.84
O2 708.95 0.92 652.23
H2 89.48 14.36 1,284.93
∑mCp= 35,479.34
230
DEHUMIDIFYING CONDENSER
Uncondensed Vapor and Inert Gases (non-condensables):
COMPONENT MASS (kg) Cp (kJ/kg · K) mCp (kJ/K)
Acrolein 218.10 1.27 276.99
N2 10,044.71 1.07 10,747.84
O2 708.95 0.92 652.23
H2 89.48 14.36 1,284.93
∑mCp= 12,961.99
Cooling Water T = 28°C
T = 90°C
Crude Acrylic Acid
T = 300°C
Condensed Crude Acrylic Acid
T = 90 °C
C-1
Uncondensed Vapor and Inert Gases T = 90°C
Acrylic Acid Water T = 90 °C
231
Crude Acrylic Acid (condensables):
Acrylic Acid:
232
Water:
233
Mass of Cooling Water:
234
ESTERIFICATION REACTOR
Reactant:
Condensed Crude Acrylic Acid
COMPONENT MASS (kg) Cp (kJ/kg · K) mCp (kJ/K)
Acrylic Acid 13,738.70 2.01 27,614.79
Water 2,038.68 4.18 8,521.68
∑mCp= 36,136.47
T = 90°C
Steam
at 200°C
Condensed Crude Acrylic
Acid
Ethanol Stream T = 25°C
Crude Ethyl Acrylate
Ethyl Acrylate Acrylic Acid Water Ethanol T = 140 °C
T = 140 °C
P=0.3-0.6 bar
R-3
Sulfuric Acid Solution (Catalyst) T=25°C
Sulfuric Acid
235
Reaction:
Ethyl Acrylate Formation:
Ethanol Acrylic Acid Ethyl Acrylate
COMPONENT MASS (kg) MW n(kmoles) ΔHf (kJ/kmol) nΔHf(kJ)
Ethyl Acrylate 18,895.33 100.08 188.80 -370,600.00 -69,970,108.24
Water 3,402.22 18.02 188.80 -241,800.00 -45,652,380.39
Acrylic Acid 13,601.31 72.04 188.80 -372,200.00 -70,272,191.82
Ethanol 8,696.26 46.06 188.80 -235,100.00 -44,387,553.76
Product:
COMPONENT MASS (kg) Cp (kJ/kg · K) mCp (kJ/K)
Ethyl Acrylate 18,895.35 1.45 27,398.26
Water 5,440.90 1.88 10,228.88
Acrylic Acid 137.38 1.36 186.84
Ethanol 87.84 0.95 83.80
Sulfuric Acid 4,967.64 1.42 7,029.21
∑mCp= 44,926.99
236
Steam at 200oC
λ = 1,938.6 kJ/kg
Steam Requirement:
COMPONENT MASS (kg) ΔHvap (kJ/kg) mΔHvap (kJ)
Ethanol 87.84 855.00 75,103.20
Acrylic Acid 137.38 628.82 86,387.29
∑mΔHvap= 161,490.49
237
HEAT EXCHANGER
COMPONENT MASS(kg) Cp(kJ/kg.K) mCp(kJ/K)
Ethyl Acrylate 18,895.33 1.45 27,398.23
Acrylic Acid 137.38 1.36 186.84
Water 5,440.90 1.88 10,431.17
Ethanol 87.84 0.95 83.80
∑mCp= 37,897.75
T =75 °C
Crude Ethyl Acrylate
Cooled Crude Ethyl Acrylate
T = 100 °C
Cooling Water T = 28°C
T = 100 °C
H-2
Ethyl Acrylate Acrylic Acid Water Ethanol T = 140 °C
238
Mass of Cooling Water:
239
CONDENSER
Acrylic Acid:
T =80 °C
Ethyl Acrylate Stream
Cooled Ethyl Acrylate (Final Product)
T = 15 °C
Cooling Water T = 28°C
T = 25 °C
C-2 Ethyl Acrylate Acrylic Acid Ethanol T = 100 °C
240
Ethyl Acrylate:
241
Ethanol:
242
Mass of Cooling Water:
243
CHAPTER VI
EQUIPMENT DESIGN
244
CHAPTER VI
EQUIPMENT DESIGN
I. INTRODUCTION
In a manufacturing process, the equipment to be used must have
appropriate design considerations. In the design of the equipment, there are
several factors to be considered: the dimensional analysis, the choice of
materials, and the energy requirement. The dimensional analysis will
determine the capacity necessary to handle the required volume of the
materials involved. The choice of materials is an important consideration in
order to account for significant parameters like resistance to chemical
reactions, strength to loads, and stresses. The energy requirement will then
determine the power consumption of the equipment in specified operating
conditions.
For each unit operation, standard operating conditions need to be set
such as temperature and pressure in order to attain equilibrium as well as to
get the desired outcome or product. For these reasons, the equipment in
which certain processes take place has to be supplied with the necessary
energy and proper design.
In case of chemical reactions, it is necessary that the equipment
provide the proper environment, space, time, temperature and pressure. The
245
mechanism whereby energy maybe supplied or removed as required in
maintaining equilibrium must also be provided.
To establish limits of space for a reaction, the material used to confine
the chemicals involved must have significant strength at the extremes of
pressure and temperature that may be encountered. A temperature limitation
would be dictated by the highest temperature used in the equipment and
could be either the maximum temperature of the reaction or the temperature
required to produce the necessary temperature gradient to ensure adequate
heat flow.
For every equipment of a certain type, there applies a certain design
equation. There is a limitation to every type of equipment and certain
equations may not be applicable at all times. Therefore, thorough
understanding of the type and nature of the equipment as well as the
materials to be handled is necessary.
For this chapter, the equipments chosen to be designed are the
Dehydration Reactor, Absorption Column, Shell and Tube Heat Exchanger,
Pervaporator, and Esterification Reactor.
246
II. SUMMARY OF ASSUMPTIONS AND DESIGN EQUATIONS
1. DEHYDRATION REACTOR
A. Assumptions
A. Vessel Design:
(Ref: Optimization of the Dehydration of Glycerol to Acrolein and a Scale
up in a Pilot Plant by Prieto, Sergio Sabater)
From Material and Energy Balance:
Ratio:
(Ref: Chemical Engineering Design Principles, Practice and Economics of
Plant and Process Design by GavinTowler, 2nd edition,)
247
B. Catalytic Fixed Bed
From Material and Energy Balance:
C. For Height of Ceramic Balls Support (CBS)
- Mass of Ceramic Balls Support is 5% of the total weight of the catalyst
(Ref: Process for Manufacturing Acrolein from Glycerol by Dubois)
D. Shell Thickness
- Ej = Efficiency of Longitudinal Joints expressed as a function
= 0.8; Double V or U butt joint for ts=1/8 to 1/4 in
- c = Allowance for Corrosion (in)
=
(Ref: Process Equipment Design by Hesse and Rushton)
- Su = 655 MPa for S31000; Ultimate Stress of Material
(Ref: ChE Handbook, 8th Edition; Table 25-11)
248
- Fm = 1.0; material factor or grade of steel
- Fr = 1.06; stress relieving factor
- Fa = 1.12; radiographing factor
- Fs = 0.2; type of steel factor
(Ref: Process Equipment Design by Hesse and Rushton)
E. Insulation Design:
For Fire Clay:
(Ref: Perry’s Chemical Engineers’ Handbook, 8th Ed, p 2-459)
F. Pump Design:
- The mechanical, kinetic, and potential energies do not change
appreciably, and the velocity and static-head terms can be dropped.
-
-
(Ref: page 208 of Unit Operations of Chemical Engineering 5th Ed. by
McCabe and Smith)
249
-
(Ref: B-1 preheater)
B. Design Equations
• Volume of Reactor:
(Ref: Chemical Reaction Engineering, Octave Levenspiel, 3rd Edition)
• For Height of Ceramic Balls Support:
• For Maximum Internal Pressure (P)
P = ρgH + 14.7
250
• Shell Thickness (ts)
Using API-ASME design equation for Cylindrical Shells
(Ref: Process Equipment Design by Hesse and Rushton, Equation 4-3)
• Head Thickness ( th )
Using API-ASME design equation for Ellipsoidal Head
(Ref: Process Equipment Design by Hesse and Rushton, Equation 4-5)
• Bottom Thickness; tb
For vessel with agitator,
tb = th
• Maximum Stress (S)
(Ref: Process Equipment Design by Hesse and Rushton, Equation 4-1)
251
G. Pump Design:
Bernoulli Equation:
(Ref: Unit Operations of Chemical Engineering 5th Ed. by McCabe and
Smith, Equation 4.32, p. 78)
Equation for Blowers and Compressors:
(Ref: Unit Operations of Chemical Engineering 5th Ed. by McCabe and
Smith, Equation 8.23)
252
2. SHELL AND TUBE HEAT EXCHANGER
A. Assumptions
1. 1 batch per day will be used.
2. BASCO TYPE 500 Model 08072 Heat Exchanger with tube diameter of
5/8” will be used.
3. 1 tube pass will be used with a Rotated Square Pitch arrangement.
4. Using 70% pump efficiency for the tube side fluid.
B. Design Equations
Heat Exchanger Design:
Heat Transfer Equation
253
Tube Side:
Using BASCO TYPE 500 Heat Exchanger Model 08072 with tube Diameter of
5/8”
Number of Tubes = 76
Shell Diameter = 8-5/8”
Surface Area of 74.5ft2
Length of Tube
Rotated Square Pitch
Clearance
No. of tubes in center row
254
Shell Side:
Shell Diameter
Baffle Diameter
(Ref: Chemical Engineering Volume 6, 4th Edition by Coulson and
Richardson, Table 12-5 p. 651)
Baffle Spacing
(Ref: of Chemical Engineering by Coulson and Richardson, Table 12.5
p. 595)
Pump Design:
(Ref: Perry’s Chemical Engineering Handbook 8th Ed. By Perry et.al, p.10-
27)
255
3. ABSORPTION COLUMN
A. Assumptions
• The plate structure must be designed to support the hydraulic loads on the plate
during operation, and the loads imposed during construction and maintenance.
Typical design values used for these loads are:
- Hydraulic load: 600 N/m2 live load on the plate, plus 3000 N/m2 over the
downcomer seal area.
- Erection and maintenance: 1500 N concentrated load on any structural
member.
• Tray spacing must be specified to compute column diameter. As spacing is
increased, column height is increased but the column diameter is reduced. A
spacing of 24 in., which provides ease of maintenance, is optimal for wide
range of conditions; however, a smaller spacing may be desirable for small-
diameter columns with large number of stages; and larger spacing is frequently
used for large-diameter columns with a small number of stages.
• Foaming factor is 0.85.
• Fraction of flooding is taken as 0.80.
256
B. Design Equations
• Entrainment flooding capacity in tray tower
(Figure 6.24. Separation Process Principles by Henley and Seader 2nd ed.)
• Correcting for CF for surface tension, foaming tendency, and the ratio of vapor
hole area Ah to tray active area A according to the empirical relationship:
(Equation 6-42. Separation Process Principles by Henley and Seader 2nd ed.)
• Flooding velocity
(Equation 6-40. Separation Process Principles by Henley and Seader 2nd ed.)
257
• Column diameter
(Equation 6-44. Separation Process Principles by Henley and Seader 2nd ed.)
• Number of theoretical plates
(Equation 14-33. Perry’s Chemical Engineers’ Handbook 8th ed.)
• Overall tray efficiency
(Using Figure 14-9. Perry’s Chemical Engineers’ Handbook 8th ed.)
• Number of actual plates
(Equation 14-44. Perry’s Chemical Engineers’ Handbook 8th ed.)
• Relationship between angle subtended by chord, chord height and chord length
(Using Figure 11.34. Chemical Engineeering Design by R. Sinnott and G.
Towler)
258
• Relation between hole area and pitch
(Using Figure 11 .35. Chemical Engineeering Design by R. Sinnott and G.
Towler)
• Vessel design equation: API-ASME Code
for shell thickness
Internal pressure
for flanged and dished head
e = 1.0
Head thickness (for head with pressure on the concave side):
Bottom thickness (for head with pressure on the convex side)
259
4. ESTERIFICATION REACTOR
A. Assumptions
• For Vessel Volume (V)
Vapor Space = 20%
• Residence time = 3 hours
(Ref: Kautter et al., Esterification of Acrylic Acid Patent No.
3458561)
• For vessel diameter and height:
In esterification reactions, a batch reactor equipped with four baffles and
a six-bladed turbine impeller is used.
(Ref: G.N. Kraai et al. / Biochemical Engineering Journal 41 (2008)
87–94)
For V= 4 to 200 m3 with turbine mixer and 4 baffles
H/D = 0.75-1.5; where: H = 1.5D
(Ref: Ch.E. HB, p.18-13)
260
• Shell Thickness:
Material for Construction: S31600
For Stainless 316 or S31600, the recommended stress at 140°C (284°F)
is 15,776.71 psi
(Ref: Plant Design and Economics for Chemical Engineers by Peters
and Timmerhaus, 5th Edition, Table 12-10 p.555)
Corrosion Factor (C) = 1/16 in
e = 0.70; for Double-Welded Butt Joint if not radiographed
• n = rotational speed =63 rpm
(Ref: Turbine & High Efficiency Axial Flow Agitators,
http://www.feldmeier.com/cutsheets/turbine_agitator.pdf)
• KT for disk turbine with six blades:
KT = 5.75
(Ref: Unit Operations in Chemical Engineering, McCabe & Smith,
Table 9.2, p. 262)
• Motor Efficiency = 80%
261
• For Heating System:
F = Safety factor = 1.5
(Ref: Engineering Page: Typical Overall Heat Transfer Coefficients
retrieved from: http://www.engineeringpage.com/technology/
thermal/transfer.html)
Tube Type: 1” BWG
Inside Diameter of the Tube =
Distance of coil from the tank wall (dc) = 6in = 0.5 ft = 0.15 m
(Ref: ChE Handbook pg. 11-21)
• For Insulation Design:
Insulating Material: Calcium Silicate
Thermal Conductivity,
(Ref: Thermal Insulation Handbook, p. 8, Table 3.3.1)
262
B. Design Equations
• For Vessel Volume (V)
Using 20% allowance for vapor space:
• For Vessel Diameter and Height
(From Ch.E. HB, p.18-13)
H = 1.5D
• For Maximum Internal Pressure (P)
P = ρgH + 14.7
• Shell Thickness (ts)
Using ASME-UPV Code, design equation for cylindrical shells (from
Peters & Timmerhaus 5th Edition, Table 12-10 p. 544):
263
• Head Thickness ( th )
Using ASME-UPV Code, design equation for ellipsoidal head (from
Peters & Timmerhaus 5th Edition, Table 12-10 p. 544):
• Bottom Thickness; tb
For vessel with agitator,
tb = th
• Impeller Diameter; Da
(p. 241, Unit Operations of Chemical Eng’g by Mc Cabe and Smith 6th
edition)
31
=DDa
• Impeller width; W
(p. 241, Unit Operations of Chemical Eng’g by Mc Cabe and Smith 6th
edition)
51
=aD
W
264
• Impeller Length; L
(p. 241, Unit Operations of Chemical Eng’g by Mc Cabe and Smith 6th
edition)
41
=aD
L
• Distance from the vessel floor; E
(p. 241, Unit Operations of Chemical Eng’g by Mc Cabe and Smith 6th
edition)
att
a DDDD
3;31
== aa
att
DDEDE
DE
====3
3;31
3;
31
• Baffle Width, J;
(p. 241, Unit Operations of Chemical Eng’g by Mc Cabe and Smith 6th
edition)
123;
121
3;
121 a
at
DJDJ
DJ
===
• Depth of Liquid in Vessel, h:
265
• Power Consumption of impeller (P)
ρ⋅⋅⋅= 53
aT DnkP
• Heating System
Heating transfer area: From ChE Handbook p. 11-20, eq. 11-39
;
F = Safety factor = 1.5
From ChE Handbook 7th Ed pg. 11-21
Distance of coil from the tank wall (dc) = 6 in = 0.1524 m
266
267
5. PERVAPORATOR
A. Assumptions
Operating Pressure = 10 bar (from Berghof Filtration and Plant Engineering)
Pfeed side = Pretentate side = 1 atm
Ppermeate side = 0.1332 atm
(European Patent No. EP 2 325 214 A1, Synthesis of Acrylic or
Methacrylic acid/Acrylate or Methacrylate Ester Polymers Using
Pervaporation)
Membrane:
Material: Polyvinyl Alcohol (PVA)
Membrane Thickness = 25 µm
Nominal Pore Size = non-porous
(European Patent No. EP 2 325 214 A1, Synthesis of Acrylic or
Methacrylic acid/Acrylate or Methacrylate Ester Polymers Using
Pervaporation)
268
Modules:
Type of Module: Tubular (Page 16, Membrane Filtration Handbook)
Module Type = MO 63G_I10HD V Berghof HyperFlux Tubular Module
Material of Construction = Fiber Reinforced Plastic (FRP), Resin
Membrane Area/module = 12.2 m2
Module Length = Tube Length = 3 m
Outer Diameter of Module = 156.4 mm
Internal Diameter of Tube = 10.3 mm
No. of Tubes/module = 72
Tube Arrangement = Triangular Pitch
Module Connection = Parallel
Feed-Permeate Differential Pressure = -0.20...+10 bar
DUMMY:
Diameter = 156.4 mm
Length = 3 m
269
BEND (VICTAULIC CONNECTION NO. 3006305)
Diameter = 168.3 mm
Thickness = 3 mm
Center Distance = 458 mm
Length = 363 mm
Material = Stainless Steel 1.4571
PERMEATE CONNECTION (VICTAULIC-CLAMP WITH FLASH GAP
SEALING)
Diameter = 60.3 mm
Socket = 50 mm
Length 1 = 58 mm
Length 2 = 57 mm
Material = Polyvinyl Chloride-Unplasticised (PVC-U)
270
INLET-OUTLET CONNECTION (VICTAULIC-CLAMP WITH FLASH
GAP SEALING)
Diameter = 168.3 mm
Thickness = 3 mm
Length = 200 mm
Material = Stainless Steel 1.4571
STRAP
Clear Height = 230 mm
Inner Width = 163 mm
Thread Length = 80 mm
Thread = M8
Material = Stainless Steel 1.4301
SADDLE
Broadth = 20 mm
Bore = 10 mm
271
Height = 20 mm
Module Center Height = 90 mm
Length = 200 mm
Distance = 170 mm
Material = Polypropylene (PP)
(Ref: Berghof Filtration and Plant Engineering, HyperFlux Tubular
Module, retrieved from http://www.lindenfiltration.com
/uploads/2/8/7/6/2876985/tub_mod.pdf)
Viscosity of the Feed = 0.6406 cP
(Ref: Perry’s Chemical Engineering Handbook, Table 2-412, 8th Edition.)
Velocity is assumed to be 5 m/s to give a turbulent flow and a good mass transfer
based on page 1036 of Unit Operations of Chemical Engineering, 5th Ed.
Operating time: 110 min
(Time-Dependence of Pervaporation Performance for the Separation of
Ethanol/Water Mixtures through Polyvinyl Alcohol Membrane, by Gewei
Li, Wei Zhang, Juping Yang, Xinping Wang)
272
Type of Pump = centrifugal pump (Membrane Filtration Handbook, p. 38)
Material of Construction = stainless steel
(Perry’s Chemical Engineering Handbook 7th Edition, page 10-24)
B. Design Equations
1. Unit Operations of ChE, McCabe and Smith, Equation 29.48, p. 1040, 7th
Edition
Where:
J = permeate flux
= mass transfer coefficient
C1 = concentration of AA at retentate
Cs = concentration of AA at feed
273
2. Unit Operation of ChE, McCabe and Smith, Equation 30.55, p. 1041, 7th Ed.
Where:
Dv = diffusivity
T = temperature (K)
ro = radius of particles (cm)
μ’ = viscosity (cP)
3. Unit Operations of ChE, McCabe and Smith, Equation 3.8, p. 59, 5th Ed.
Where:
Nre = Reynolds Number
D = Diameter of Vessel
v = Velocity of fluid
µ = viscosity
274
4. Unit Operation of ChE, McCabe and Smith, Equation 3.10, p. 53, 7th Edition
Where:
NSc = Schmidt Number
µ = viscosity
ρ = density
Dv = diffusivity
5. Unit Operations of ChE, McCabe and Smith, Equation 17.71, p. 545, 7th Edition
Where:
NSh = Sherwood Number
Re = Reynolds Number
Sc = Schmidt Number
275
6. Unit Operations of ChE, McCabe and Smith, Equation 17.71, p. 545, 7th Edition
Where:
= mass transfer coefficient
NSh = Sherwood Number
D = diameter of tube
Dv = diffusivity
7. Unit Operations of Chemical Engineering, McCabe and Smith, Equation 30.49,
p. 1037, 5th Edition:
Where:
u = permeate flux
Qm = membrane permeability
ΔP = transmembrane pressure
276
8. Transmembrane Pressure (ΔP):
Where:
= partial vapor pressure of more volatile component on feed side
= partial vapor pressure of more volatile component on permeate side
9. ChE Handbook 7th Edition, p. 10-23 Equation 10-50:
Where:
H = total dynamic head (Pa)
Q = capacity (m3/hr)
10. From Berghof Module Data Sheet:
277
11. From Berghof Module Data Sheet:
Where:
Pressure Drop along Module = (kPa)
v =Cross Flow Velocity (m/s)
L = Module Length (m)
278
III. EQUIPMENT DESIGN
279
SPECIFICATION SHEET IDENTIFICATION Date : Name Dehydration Reactor Code R-1 Unit/s required 1 FUNCTION To convert Glycerol to Acrolein OPERATION Continuous TYPE Fixed Bed Reactor VOLUMETRIC FLOWRATE 1.24 m3/hr MATERIAL HANDLED Glycerol, Water, Tungstated Zirconia
(catalyst) DESIGN DATA Pressure (P) 183.2 kPa Density (ρ) 1,141.7 kg/m3
Temperature 280oC Specifications Material of Construction S31600 Diameter 1.1 m Height (H) 4.3 m Head thickness (th) 3 mm Shell thickness (ts) 3 mm Bottom thickness (tb) 3 mm
Type of Joint Double V/U butt joint Joint Efficiency 80 %
Catalyst Bed Height 2 m Diameter 1.1 m
Catalyst Bed Support Material Alumina ceramic ball Diameter 1.1 m Height (above the catalyst) 0.12 m Height (bottom of the catalyst) 0.23 m
Insulation Design Outside Diameter 1.18 m Thickness 40 mm Insulating Material Fire Clay Thermal Conductivity 1.02
Compressor Design Compressor Type Centrifugal Compressor Power Requirement 1.5 HP
280
Fixed Bed Reactor
Inlet
th= 3 mm
th= 3 mm
ts= 3 mm
Hbed= 2 m
Hbed support= 0.12 m
Hbed support= 0.23 m
Catalyst Dump Flange
D = 1.1 m
Outlet
H = 4.3 m
281
Design Calculation
From Material & Energy Balance:
Feed:
Component Density (kg/m3) kg kgmol Glycerol 1,261.00 20,400.00 221.55
Water 1,000.00 13,600.00 755.56
TOTAL 34,000.00 977.10
Reaction Involved:
For acrolein:
glycerol acrolein
glycerol acetone
90% Conversion (1)
10% Convesion (2)
acetone acetol
282
For continuous process:
Calculation for space time
From Chemical Reaction Engineering, Octave Levenspiel, 3rd Edition
Derivation:
For reactor containing catalyst particle:
At steady state a material balance for reactant A gives
In symbols
In differential form
Thus
Elementary slice of solid catalyzed reactor
283
Where:
(Ref: Optimization of the Dehydration of Glycerol to Acrolein and a Scale up in a
Pilot Plant by Prieto, Sergio Sabater)
Based from the graph, to obtain a 100% conversion of glycerol should be equal
to 0.6
(Ref: Chemical Reaction Engineering, Octave Levenspiel, 3rd Edition)
284
For reaction (1)
From Material and Energy Balance:
For reaction (2)
From Material and Energy Balance:
285
With a safety factor of 20%:
For volume of catalyst: From Material and Energy Balance:
For volume of Ceramic Balls Support (CBS): (Ref: Process for Manufacturing Acrolein from Glycerol by Dubois)
(Ref:Chemical Engineering Design Principles, Practice and Economics of Plant
and Process Design by GavinTowler, 2nd edition)
286
Ratio:
For Catalytic Fixed Bed Height and Diameter:
For Height of Ceramic Balls Support (CBS): (Ref: Process for Manufacturing Acrolein from Glycerol by Dubois)
From Albright’s Chemical Engineering Handbook by Lyle F. Albright
287
Shell Thickness:
From Process Equipment Design by Hesse and Ruston, Equation 4-3
Using API-ASME design equation for Cylindrical Shells
Where:
ts = Shell Thickness (in)
P = Maximum Allowable Working Pressure (psi)
D = Inside Diameter of the Shell before Corrosion Allowance is
added (in)
S = Maximum Allowable Working Stress (psi) using S31000
Ej = Efficiency of Longitudinal Joints expressed as a fraction
= 0.8; Double V or U butt joint for ts=1/8 to 1/4 in (Process
Equipment Design by Hesse and Ruston)
c = Allowance for Corrosion (in)
=
Maximum Stress (S)
From Process Equipment Design by Hesse and Ruston, Equation 4-1
Where:
Su = 655 MPa for S31000; Ultimate Stress of Material (ChE
Handbook, 8th Edition; Table 25-11)
Fm = 1.0; material factor or grade of steel
Fr = 1.06; stress relieving factor
Fa = 1.12; radiographing factor
Fs = 0.2; type of steel factor
288
For Maximum Internal Pressure:
289
Head and Bottom Thickness:
From Process Equipment Design by Hesse and Ruston, Equation 4-5
Using API-ASME design equation for Ellipsoidal Head
Insulation Design:
From Material & Energy Balance:
From ChE Handbook, 7th Ed, p 2-335
For a reactor with temperature of 280°C, the recommended insulation material is
Fire Clay with a thermal conductivity of
Di
Do
290
Compressor Design: Bernoulli Equation:
For blowers and compressors: (From page 208 of Unit Operations of Chemical Engineering 5th Ed. by McCabe and Smith)
In blowers and compressors the mechanical, kinetic, and potential energies do not change appreciably, and the velocity and static-head terms can be dropped. Also, on the assumption that the compressor is frictionless, and with this simplifications the equation becomes
291
Power requirement:
292
SPECIFICATION SHEET IDENTIFICATION Date Name Heat Exchanger Code H-1 Units required 1 FUNCTION To cool the Crude Acrolein OPERATION Continuous TYPE Shell and Tube Heat Exchanger DUTY 7,500,000 kJ/day
MATERIAL HANDLED Acrolein, Acetol, Water, Hydrogen, Oxygen
DESIGN DATA Shell Side Design Tube Side Design
Fluid Handled Water Fluid Handled Crude Acrolein Mass Flow rate 9.44 kg/s
Mass Flow rate 7.90 kg/s Volumetric Flow rate 0.0094 m3/s Velocity 0.2106 m/s Velocity 0.5935 m/s
Temperature 28°C 90°C Temperature 280°C 150°C Outer Diameter 16 mm
Bundle Diameter 204 mm Inside Diameter 14 mm Shell Diameter 219 mm Length of tubes 2 m Wall Thickness 3 mm Tube surface area 4.70 m2 Baffle Spacing 43.8 mm Number of tubes 76 Baffle Diameter 214 mm Tube Pitch 19.85 mm
Type of Joint Double-Welded Butt Joint Pressure Drop 21.9 kPa
Joint Efficiency 80 % Clearance 3.97 mm Shell Material G10200 Tube Material S50200 Pump Design Pump Type Centrifugal Power Requirement 4 HP
293
Shell and Tube Heat Exchanger
2 m
294
Tube Arrangement
Outside Diameter = 5/8 in = 15.88 mm
Using Rotated Square Pitch
(From Plant Design and Economics by Peter and Timmerhaus)
Tube Pitch, pt = 1.25 Do = 1.25 (15.88 mm) = 19.85 mm
Clearance = 0.25 Do = 0.25 (15.88 mm) = 3.97 mm
19.85 mm
3.97 mm
295
Design Calculations for Heat Exchanger
From Material & Energy Balance:
Amount of Heat, Q = 7,375,680.66 kJ/day
Cooling Water Mass Flow = 28,432.74 kg/day
Design Operation:
Operation: 1 Batch per Day
Operating Time: 1 hour
Heat Transfer Equation:
Logarithmic Mean Temperature Difference
Crude Acrolein Cooling Water
Temperature in (oC) 280 28
Temperature out (oC) 150 90
296
Overall Heat Transfer Coefficient
Overall Heat transfer coefficient of shell and tube heat exchanger
(Ref: Chemical Engineering Vol. 6, 4th Edition by Coulson and
Richardson, Table 12.1 p. 637)
Heat Transfer Area
297
Tube Side Design
Fluid Handled : Crude Acrolein
Mass Flow Rate : 34,000 kg/day
Mass Flow Rate
Volumetric Flow Rate (GPM)
For a Surface Area of = 4.7012 m2 ≈ 50.60 ft2
(Ref: Basco Type 500 Heat Exchangers Model 08072 Standard Straight Tube
Type)
Surface Area = 62.1 ft2
Number of tubes = 76
Tube Outside Diameter (Do) = 5/8” ≈ 15.88 mm
298
Shell Diameter = 8 5/8” ≈ 0.2191 m
Maximum Flow Rate (GPM) = 461 GPM
Using 5/8 in OD BWG 20,
Outside Diameter (Do) = 15.88 mm
Inside Diameter (Di) = 14.097 mm
Length of Tubing Required
Tube Side Velocity
From BASCO TYPE 500 HEAT EXCHANGERS
Velocity factor = 1.47 (for 5/8” tubing)
299
Pitch Type: Rotated Square Pitch
Tube Pitch, pt = 1.25 Do = 1.25 (15.88 mm) = 19.85 mm
Clearance = 0.25 Do = 0.25 (15.88 mm) = 3.97 mm
Pressure Drop
(Ref: Equation 12.18 p.666 Chemical Engineering Vol. 6, 4th Edition by
Coulson and Richardson)
Evaluating for Jf,
Viscosity of solution mostly Acrolein= 0.05632 Pa-s
(Ref: www.epa.gov/hpv/pubs/summaries/acriolein/c13462rs.pdf)
From Fig. 12.24 p. 668 of Chemical Engineering Vol. 6 4th Ed. By Coulson and
Richardson
0
300
Therefore:
301
Pump Design
Pressure Head
(Ref: p. 10-27 Perry’s Chemical Engineering Handbook 8th Ed. By Perry et.al)
302
Shell Side Design
Fluid Handled : Water
Mass Flow Rate : 28,432.74 kg/day
Mass Flow Rate
Bundle Diameter
Shell Diameter
From BASCO TYPE 500 HEAT EXCHANGERS
Baffle Diameter and Spacing
(Ref: Chemical Engineering Volume 6, 4th Edition by Coulson and Richardson,
Table 12-5 p. 651)
303
Number of tubes in center row
Pressure Drop
(Ref: Chemical Engineering Vol. 6, 4th Edition by Coulson and Richardson)
Velocity, us
From BASCO TYPE 500 HEAT EXCHANGERS
Velocity factor of shell = 10
304
Evaluating diameter, de, from Eq. 12.22 p. 672 of Chemical Engineering Vol. 6 4th
Ed. By Coulson and Richardson
Evaluating for Jf,
Viscosity of water at average temperature of 37.5oC= 0.704 mPa-s
(Ref: Perry’s ChE Handbook 8th Edition, T 2-313 p. 2-432)
From Fig. 12-30 p. 674 of Chemical Engineering Vol. 6 4th Ed. By Coulson
and Richardson
305
Therefore:
Using 5/8 in OD BWG 20,
Outside Diameter (Do) = 15.88 mm
Inside Diameter (Di) = 14.097 mm
Vtubes = NT x S x LT
D = 2.8905 m (superficial diameter for the flow of cooling water)
306
Shell Thickness
Material of Construction : G10200
Joint : Double Welded V-butt
Efficiency : 0.80
Corrosion Allowance : 1/16 in
From Process Equipment Design by Hesse and Rushton, Equation 4-3
Using API-ASME design equation for Cylindrical Shells
Where:
ts = Shell Thickness (in)
P = Maximum Allowable Working Pressure (psi)
D = Inside Diameter of the Shell before Corrosion Allowance is
added (in)
S = Maximum Allowable Working Stress (psi) using G10200
e = Efficiency of Longitudinal Joints expressed as a fraction
307
= 0.8; Double V or U butt joint for ts=1/8 to 1/4 in (Process
Equipment Design by Hesse and Rushton)
c = Allowance for Corrosion (in)
=
Working Pressure = ρgh; h= superficial diameter
Pressure Head = Atmospheric Pressure + Working Pressure
= 101 325 Pa + 1000 kg/m3 (9.8 m/s2) (2.8905 m)
= 129 651.90 Pa = 18.8045 psi
From table 4-1 of Process Equipment Design by Hesse and Rushton,
Fs = 25% for temperatures up to 650 ºF
S =Su x Fm x Fa x Fr x Fs (Eq. 4-1 p.84 of PED by Hesse and Ruston)
Su = 65000 psi (G10200; ChE Handbook 8th ed p 25-32 table 25-8)
Fm = 1.0
Fr = stress relieving factor = 1.0
Fa = radiographing factor = 1.0
Fs = 0.25
308
Assuming stress relieving and radiographing factors are not employed:
S = 65,000 psi x 1.0 x 1.0 x 1.0 x 0.25
S = 16,250 psi
From Process Equipment Design by Hesse and Rushton, Equation 4-3
Using API-ASME design equation for Cylindrical Shells
309
SPECIFICATION SHEET Item: Absorption Column Number required: 1 Code: A-1 Function: To purify acrolein from the dehydration reactor Operation: Continuous
Type: Tray column Cross flow
INTERNAL CONDITIONS Top Bottom Vapor to tray Crude acrolein Rate 3.9 m3/s 6.9 m3/s Density 1.2 kg/m3 0.68 kg/m3 Pressure 100 kPa 100 kPa Temperature 55°C to 60°C 140°C to 150°C Liquid from tray Water Rate 2.22 L/s 5.1 L/s Density 1000 kg/m3 1000 kg/m3 Temperature 25°C to 30°C 55°C to 60°C Viscosity 0.85 cP 0.50 cP OPERATING DATA Column diameter 1.5 m Tray space 600 mm Total trays in section 5 trays Column height 3.5 m Number of passes Single pass Downcomer type Segmental Weir height 100 mm Clearance height 90 mm Hole size 13 mm Ø Hole pitch 35 mm ∆ TECHNICAL/MECHANICAL DATA Tray type Sieve tray Tray material Stainless steel Tray thickness 6 mm Downcomer material Stainless steel Downcomer bar thickness 6 mm Support ring material Stainless steel Support ring thickness 6 mm Support ring width 50 mm
310
CONSTRUCTION AND MATERIALS Material of Construction: Stainless steel UNS S31600 Shell thickness: 4 mm Weld profile: Single U butt joint Welding efficiency: 70% Head type: Flanged and dished head Head thickness: 4 mm Bottom thickness: 7 mm PUMP DESIGN Pump type: Centrifugal Power requirement: 1.5 HP
311
Absorption Column
600 mm
3.5 m
Gas In
6 mm
4 mm
Gas Out Liquid
Liquid
Sieve tray
1.5 m
312
PLATE AREA
TOP VIEW OF ARRANGEMENT ON A TRAY
d = 13 mm
p = 35 mm
313
TYPICAL CROSS-FLOW PLATE (SIEVE)
314
MATERIALS HANDLED
Basis: 2 hours operation
Feed: 34,000 kg
Liquid properties (water)
Density, ρx
Viscosity, µx @30°C
Surface tension
315
Properties of Gas (acrolein stream)
316
TRAY-TOWER DESIGN
Diameter
“The overall height of the column will depend on the plate spacing. Plate
spacing from 0.15 m (6 in.) to 1 m (36 in.) are normally used. The spacing chosen
will depend on the column diameter and operating conditions. Close spacing is
used with small-diameter columns, and where head room is restricted; as it will be
when a column is installed in a building. For columns above 1 m diameter, plate
spacing of 0.3 to 0.6 m will normally be used, and 0.5 m (18 in.) can be taken as
an initial estimate. This would be revised, as necessary, when the detailed plate
design is made.”
(Chemical Engineeering Design by R. Sinnott and G. Towler)
317
estimate: for tray spacing = 24 in., from Fig. 6.24, CF = 0.39 ft/s
Fig.6.24 (Separation Process Principles by Henley and Seader 2nd ed.)
318
Correcting for CF for surface tension, foaming tendency, and the ratio of
vapor hole area Ah to tray active area A according to the empirical
relationship:
(Equation 6-42. Separation Process Principles by Henley and Seader 2nd ed.)
Solving for flooding velocity
(Equation 6-40. Separation Process Principles by Henley and Seader 2nd ed.)
319
Column diameter
(Equation 6-44. Separation Process Principles by Henley and Seader 2nd ed.)
Typically, the fraction of flooding, f, is taken as 0.80.
Tray spacing must be specified to compute column diameter. As spacing is
increased, column height is increased but the column diameter is reduced. A
spacing of 24 in., which provides ease of maintenance, is optimal for wide range
of conditions; however, a smaller spacing may be desirable for small-diameter
columns with large number of stages; and larger spacing is frequently used for
large-diameter columns with a small number of stages.
320
Tray spacing with their corresponding column diameter:
Tray Spacing Computed diameter
36 in. 1.3 m
24 in. 1.5 m
18 in. 1.8 m
12 in. 2.0 m
9 in. 2.3 m
6 in. 2.5 m
Column diameter = 1.5 m
Tray spacing = 24 in. (600 mm)
Number of Theoretical Plates
(Equation 14-33. Perry’s Chemical Engineers’ Handbook 8th ed.)
321
Henry’s law constant for acetol is 0.43 atm/mole fraction:
322
Tray Efficiency
“The O’Connell parameter for gas absorbers is ρL/KMμL, where ρL is the
liquid density, lb/ft3; μL is the liquid viscosity, cP; M is the molecular weight of the
liquid; and K = y°/x. “. (Perry’s Chemical Engineers’ Handbook 8th ed., p. 14-15)
According to the O’Connell graph for absorbers (Using Fig. 14-9. Perry’s
Chemical Engineers’ Handbook 8th ed.) the overall tray efficiency is estimated to
be 60 percent.
323
Number of Actual Plates
(Equation 14-44. Perry’s Chemical Engineers’ Handbook 8th ed.)
The required number of actual trays is 3/0.60 = 5 trays
Height of the Column
“The required height of a gas absorption tower for physical solvents
depends on (1) the phase equilibria involved; (2) the specified degree of removal
324
of the solute from the gas; and (3) the mass-transfer efficiency of the device. These
three considerations apply to both tray and packed towers. Items 1 and 2 dictate
the required number of theoretical stages (tray tower). Item 3 is derived from the
tray efficiency and spacing (tray tower). For tray towers, the approximate design
methods described below may be used in estimating the number of theoretical
stages, and the tray efficiencies and spacings for the tower.” (Perry’s Chemical
Engineers’ Handbook 8th ed., p. 14-9)
actual plates = 5 plates
tray spacing = 600 mm
tray thickness = 6 mm
height of the column = (5 x 600 mm) + (5 x 6 mm) = 3030 mm
Vapor space = 20%
height of the column = 3030 mm x 1.2 = 3600 mm
height of column = 3.5 m
325
PRIMARY TRAY CONSIDERATIONS
Number of Passes
“Trays smaller than 1.5-m (5-ft) diameter seldom use more than a single
pass; those with 1.5- to 3-m (5- to 10-ft) diameters seldom use more than two
passes. Four-pass trays are common in high liquid services with towers larger
than 5-m (16-ft) diameter.” (Perry’s Chemical Engineers’ Handbook 8th ed., p. 14-
29)
Number of passes: Single Pass
Tray Spacing
“Taller spacing between successive trays raises capacity, leading to a
smaller tower diameter, but also raises tower height. There is an economic
tradeoff between tower height and diameter. As long as the tradeoff exists, tray
spacing has little effect on tower economies and is set to provide adequate access.
326
In towers with larger than 1.5-m (5-ft) diameter, tray spacing is typically 600 mm
(24 in), large enough to permit a worker to crawl between trays. In very large
towers (>6-m or 20-ft diameter), tray spacings of 750 mm (30 in) are often used.
In chemical towers (as distinct from petrochemical, refinery, and gas plants), 450
mm (18 in) has been a popular tray spacing. With towers smaller than 1.5 m (5 ft),
tower walls are reachable from the manways, there is no need to crawl, and it
becomes difficult to support thin and tall columns, so smaller tray spacing
(typically 380 to 450 mm or 15 to 18 in) is favored. Towers taller than 50 m (160
ft) also favour smaller tray spacings (400 to 450 mm or 16 to 18 in).” (Perry’s
Chemical Engineers’ Handbook 8th ed., p. 14-29)
Tray spacing: Using 1.5 meter diameter, the tray spacing is 24 in. (600 mm)
Outlet Weir
“The outlet weir should maintain a liquid level on the tray high enough to
provide sufficient gas-liquid contact without causing excessive pressure drop,
downcomer backup, or a capacity limitation. Weir heights are usually set at 40 to
80 mm (1.5 to 3 in). In this range, weir heights have little effect on distillation
efficiency [Van Winkle, Distillation, McGraw-Hill, New York, 1967; Kreis and
Raab, IChemE Symp. Ser. 56, p. 3.2/63 (1979)]. In operations where long
residence times are necessary (e.g., chemical reaction, absorption, stripping)
327
taller weirs do improve efficiency, and weirs 80 to 100 mm (3 to 4 in) are more
common (Lockett, Distillation Tray Fundamentals, Cambridge University Press,
Cambridge, England, 1986).” (Perry’s Chemical Engineers’ Handbook 8th ed., p.
14-29)
Weir height: 4 in. (100 mm)
Downcomers
“A downcomer is the drainpipe of the tray. It conducts liquid from one tray
to the tray below. Due to the density difference, most of this gas disengages in the
downcomer and vents back to the tray from the downcomer entrance. Some gas
bubbles usually remain in the liquid even at the bottom of the downcomer, ending
on the tray below [Lockett and Gharani, IChemE Symp. Ser. 56, p. 2.3/43 (1979)].
The straight, segmental vertical downcomer (Fig. 14-23a) is the most common
downcomer geometry. It is simple and inexpensive and gives good utilization of
328
tower area for downflow.” (Perry’s Chemical Engineers’ Handbook 8th ed., p. 14-
31)
Figure 11.34. Relationship between angle subtended by chord, chord height
and chord length
(Ref: Chemical Engineeering Design by R. Sinnott and G. Towler)
329
Clearance under the Downcomer
“Restricting the downcomer bottom opening prevents gas from the tray
from rising up the downcomer and interfering with its liquid descent (downcomer
unsealing). A common design practice makes the downcomer clearance 13 mm
(0.5 in) lower than the outlet weir height (Fig. 14-25) to ensure submergence at
all times [Davies and Gordon, Petro/Chem Eng., p. 250 (November 1961)]. This
practice is sound in the froth and emulsion regimes, where tray dispersions are
liquid-continuous, but is ineffective in the spray regime where tray dispersions are
gas-continuous and there is no submergence. Also, this practice can be
unnecessarily restrictive at high liquid loads where high crests over the weirs
sufficiently protect the downcomers from gas rise.” (Perry’s Chemical Engineers’
Handbook 8th ed., p. 14-31)
Clearance height: 3.5 in. (90 mm)
330
Hole Sizes
“Small holes slightly enhance tray capacity when limited by entrainment
flood. Reducing sieve hole diameters from 13 to 5 mm (½ to 3/16 in) at a fixed hole
area typically enhances capacity by 3 to 8 percent, more at low liquid loads. Small
holes are effective for reducing entrainment and enhancing capacity in the spray
regime (QL < 20 m3/hm of weir). Hole diameter has only a small effect on
pressure drop, tray efficiency, and turndown. On the debit side, the plugging
tendency increases exponentially as hole diameters diminish. Smaller holes are
also more prone to corrosion. While 5-mm (3/16-in) holes easily plug even by scale
and rust, 13-mm (½ in) holes are quite robust and are therefore very common. The
small holes are only used in clean, noncorrosive services. Holes smaller than 5
mm are usually avoided because they require drilling (larger holes are punched),
which is much more expensive. For highly fouling services, 19- to 25-mm (¾ to 1-
in) holes are preferred.” (Perry’s Chemical Engineers’ Handbook 8th ed., p. 14-
31)
Hole size: 0.5 in. (13 mm)
331
Provisional Plate Design
Perforated Area
332
Figure 11 .35. Relation between hole area and pitch
(Ref: Chemical Engineeering Design by R. Sinnott and G. Towler)
From figure above, lp/dh = 2.7 (satisfactory, within 2.5 to 4.0), lp = 35 mm
333
Number of Holes
MATERIAL OF CONSTRUCTION
Using API-ASME Code
For Shell Thickness, tS
For stainless 316 or S31600:
334
The plate structure must be designed to support the hydraulic loads on the
plate during operation, and the loads imposed during construction and
maintenance. Typical design values used for these loads are:
Hydraulic load: 600 N/m2 live load on the plate, plus 3000 N/m2 over the
downcomer seal area.
Erection and maintenance: 1500 N concentrated load on any structural member.
335
Verify if Fa and Fr are mandatory
Radiographing and relieving may not be employed since 0.14 in. < 0.91 in.
336
For Flanged and Dished Head Thickness
• Head thickness (for head with pressure on the concave side)
• Bottom thickness (for head with pressure on the convex side)
337
Pump Design:
Power output (theoretical)
(Equation 10-51. Perry’s Chemical Engineers’ Handbook 8th ed.)
Power Requirement:
For a basis of 70% efficiency of the motor:
Power actual
(Equation 10-55. Perry’s Chemical Engineers’ Handbook 8th ed.)
338
SPECIFICATION SHEET IDENTIFICATION Date : Name Esterification Reactor Code R-3 Unit/s required 1 FUNCTION To convert Acrylic Acid to Ethyl Acrylate OPERATION Batch TYPE Stirred Tank CAPACITY 35 m3 MATERIAL HANDLED Acrylic Acid, Ethanol, Water, Sulfuric Acid DESIGN DATA Pressure (P) 147.8 kPa Density (ρ) 1,020.20 kg/m3
Temperature 140°C SPECIFICATIONS Material of Construction S31600 Diameter 3.1 m Height (H) 4.7 m Head thickness (th) 5 mm Shell thickness (ts) 5 mm Bottom thickness (tb) 5 mm Type of Joint Double-Welded Butt Joint Joint Efficiency 70 % IMPELLER DESIGN Impeller Type Turbine Impeller Diameter
(Da) 1 m
No. of Blades 6 Impeller Length (L) 0.3 m No. of Baffles 4 Impeller Width (W) 0.2 m Impeller Power Requirement
13 HP Impeller Height from Bottom (E)
1 m
Rotational Speed 63 rpm Width of Baffles (J) 0.3 m HEATING COIL DESIGN Heat Transfer Area
4.6 m2 Number of Turns 8
Temperature 200°C Diameter of the Coil 2.3 m Diameter of the Tube
1 in Distance between Coils
0.4 m
Length of the Coil 58.2 m Height of Coils 3.5 m
339
INSULATION DESIGN Outside Diameter 3.11 m Insulating Material Calcium Silicate Thickness 2 mm Thermal
Conductivity 0.05728 W/(m·K)
340
Esterification Reactor
341
Batch reactor equipped with four baffles using a 6-blade turbine impeller
Top view
Side View
Baffle
Blade
342
Design Calculations
For Reactor Volume:
(Ref: Kautter et al., Esterification of Acrylic Acid Patent No. 3458561)
From Material & Energy Balance:
Feed:
Component Density (kg/m3) kg
Acrylic acid 1,050 13,738.70
Ethanol 790 8,784.10
Water 1,000 2,146.28
Sulfuric Acid 1,840 4,967.64
TOTAL 29,636.72
343
With a vapor space of 20%:
For vessel diameter and height:
In esterification reactions, a batch reactor equipped with four baffles and a six-
bladed turbine impeller is used.
(Ref: G.N. Kraai et al. / Biochemical Engineering Journal 41 (2008) 87–94)
(Ref: Ch.E. HB, p.18-13)
For V= 4 to 200 m3 with turbine mixer and 4 baffles
H/D = 0.75-1.5;
Basis: H = 1.5D
Using cylindrical vessel,
344
For Maximum Internal Pressure:
Shell Thickness:
From Plant Design and Economics for Chemical Engineers by Peters and
Timmerhaus, 5th Edition, Table 12-10 p.555:
For Stainless 316 or S31600, the recommended stress at 140°C (284°F) is:
345
Using ASME-UPV Code, design equation for cylindrical shells (from Peters and
Timmerhaus 5th Edition, Table 12-10 p. 554):
Where:
tS = shell thickness (in)
P = maximum allowable working pressure (psi)
r = inside radius of the shell before corrosion allowance is added (in)
S = maximum allowable working stress (psi) using S31600
e = efficiency of joints expressed as a fraction
= 0.70; for Double-Welded Butt Joint if not radiographed (From Plant
Design and Economics for Chemical Engineers by Peters and Timmerhaus
5th Edition, Table 12-10 p. 555)
c = allowance for corrosion (in)
= 1/16 in
346
Head and Bottom Thickness:
Using ASME-UPV Code, design equation for ellipsoidal head (from Peters and
Timmerhaus 5th Edition, Table 12-10 p.554):
Impeller Design:
(Ref: Unit Operations by McCabe &Smith 6th Edition p.241)
Impeller Diameter; Da
Impeller width; W
347
Impeller Length; L
Distance vessel floor; E
Baffle Width, J;
Depth of Liquid in Vessel, h;
Volume of Impeller:
348
Power Consumption of Impeller:
From Turbine & High Efficiency Axial Flow Agitators,
http://www.feldmeier.com/cutsheets/turbine_agitator.pdf:
Speed range for commercially available turbine agitator is 63 to 73 rpm.
To compute for Reynolds Number:
n = rotational speed = 63 rpm = 1.05 rev/s
Da = impeller diameter = 1.03 m
NRe = 438,782.51
Since Re>104 ∴flow is turbulent
KT for disk turbine with six blades (table 9.2, McCabe & Smith p. 262)
KT = 5.75
349
For a motor efficiency of 80%,
Heating Coil Design:
(From ChE Handbook p. 11-20, eq. 11-39)
QF = UAΔTLM
; F = Safety factor = 1.5
From Material and Energy Balance:
Temperature of Feed:
350
°C
Steam T1 200
T2 200
Liquid t1 83
t2 140
(Ref: Engineering Page: Typical Overall Heat Transfer Coefficients retrieved
from: http://www.engineeringpage.com/technology/thermal/transfer.html)
351
From ChE Handbook 7th Ed pg. 11-21
Economical Diameter of the Tube for shop fabrication = 25.4 mm = 1 in BWG
Diameter of the Tube =
Length of coil:
From ChE Handbook pg. 11-21
Distance of coil from the tank wall (dc) = 6in = 0.5 ft = 0.15 m
352
Total Volume of Tank, VT:
353
Insulation Design:
From ChE Handbook, 8th Ed, p 2-459
For Calcium Silicate:
ri
ro
354
SPECIFICATION SHEET IDENTIFICATION Name of Equipment Pervaporator Equipment Code PV – 1 Number of Unit/s Required 1
Function To remove water from the Ethyl Acrylate product stream
Operation Continuous Type Tubular
Materials Handled Ethyl Acrylate, Acrylic Acid, Ethanol, Water
DESIGN DATA Capacity 14.39 m3/hr Operating Pressure 10 bar Transmembrane Pressure 0.25 bar Power Requirement 7 HP MEMBRANE DESIGN
Membrane Material Polyvinyl Alcohol (PVA) Thickness 25 µm Nominal Pore Size Non-Porous Total Membrane Area 381.3 m2
MODULE DESIGN
Module Type MO 63G_I10HD V Berghof HyperFlux Tubular Module
Material of Construction Fiber Reinforced Plastic (FRP), Resin Membrane Area/module 12.2 m2
Length 3 m Outer Diameter of Module 156.4 mm Internal Diameter of Tube 10.3 mm No. of Tubes/module 72 Tube Arrangement Triangular Pitch Total Number of Modules Required 32 Module Connection Parallel Module Arrangement 32 rows Feed-Permeate Differential Pressure -0.20...+10 bar Pressure Drop along Module 3.48 bar
355
MODULE CONNECTIONS DESIGN DUMMY Diameter 156.4 mm Length 3 m No. of Dummy Required 32 BEND VICTAULIC CONNECTION NO. 3006305 Diameter 168.3 mm Thickness 3 mm Center Distance 458 mm Length 363 mm Material Stainless Steel 1.4571 No. of Bends Required 32 PERMEATE CONNECTION VICTAULIC-CLAMP WITH FLASH GAP SEALING Diameter 60.3 mm Socket 50 mm Length 1 58 mm Length 2 57 mm
Material Polyvinyl Chloride-Unplasticised (PVC-U)
No. of Permeate Connections Required 64 INLET-OUTLET CONNECTION VICTAULIC-CLAMP WITH FLASH GAP SEALING Diameter 168.3 mm Thickness 3 mm Length 200 mm Material Stainless Steel 1.4571 No. of Inlet-Outlet Connection Required 128
MODULE FIXING PARTS DESIGN STRAP Clear Height 230 mm Inner Width 163 mm Thread Length 80 mm Thread M8 Material Stainless Steel 1.4301 No. of Strap Required 192 SADDLE Broadth 20 mm
356
Bore 10 mm Height 20 mm Module Center Height 90 mm Length 200 mm Distance 170 mm Material Polypropylene (PP) No. of Saddles Required 192
357
Cutaway of the MO 63G_I10HD V Berghof HyperFlux Tubular Module
One Unit Module Assembly Overview
358
359
Module Design: Using commercially available MO 63G_I10HD V Berghof HyperFlux Tubular Module from Berghof Filtration and Plant Engineering Data Sheets:
Dummy Design:
360
Inlet-/Outlet Connection Design:
Permeate Connection Design:
361
Bend Design:
Module Fixing Parts Design: Strap:
362
Saddle:
363
Detailed Computations:
Materials Handled:
Quantity (kg) Feed Permeate Retentate
Ethyl Acrylate 18895.35 0 18895.35
Acrylic Acid 137.38 0 137.38
Water 5548.51 5548.51 0
Ethanol 87.84 0 87.84
Total 24669.08 5548.51 19120.57
Temperature (°C) 100 100 100
Pressure (atm) 1 0.1332 1
Feed:
Substance Size (nm)
Molecular Weight (kg/kgmol)
Density (kg/m3)
Volume (m3)
Mass (kg) Mass Fraction (Xi)
Ethyl Acrylate
45 100.08 920 20.54 18895.35 0.7660
Acrylic Acid
35 72.04 1050 0.1308 137.38 0.0056
Water 0.275 18.02 1000 5.549 5548.51 0.2249 Ethanol 0.44 46.06 790 0.1112 87.84 0.003561 TOTAL 936.96 26.33 24669.08 1
364
Permeate:
Substance Size (nm)
Molecular Weight (kg/kgmol)
Density (kg/m3)
Volume (m3)
Mass (kg) Mass Fraction (Xi)
Water 0.275 18.02 1000 5.549 5548.51 1
Retentate:
Substance Size (nm)
Molecular Weight (kg/kgmol)
Density (kg/m3)
Volume (m3)
Mass (kg) Mass Fraction (Xi)
Ethyl Acrylate
45 100.08 920 20.54 18895.35 0.9882
Acrylic Acid
35 72.04 1050 0.1308 137.38 0.007185
Ethanol 0.44 46.06 790 0.1112 87.84 0.004594 TOTAL 920.12 20.78 19120.57 1
To solve for Diffusivity:
Unit Operation of ChE, McCabe and Smith, Equation 30.55, p. 1041, 7th Edition
Where: Dv = diffusivity
T = temperature (K)
= radius of particles (cm) = 45 nm ≈ 4.5x10-6 cm
μ’ = viscosity (cP) = 0.6406 cP
365
To solve for Reynolds Number:
Unit Operations of ChE, McCabe and Smith, Equation 3.8, p. 59, 5th Ed.
To solve for Schmidt Number:
Unit Operation of ChE, McCabe and Smith, Equation 3.10, p. 53, 7th Edition
7216.23
366
To solve for Sherwood Number (for high Schmidt Number)
Unit Operations of ChE, McCabe and Smith, Equation 17.71, p. 545, 7th Edition
48,157.45
To solve for Mass Transfer Coefficient (Kc):
Unit Operations of ChE, McCabe and Smith, Equation 17.71, p. 545, 7th Edition
Where:
NSh = Sherwood Number
D = diameter of tube
Dv = diffusivity
367
To solve for permeate flux (u):
Unit Operations of ChE, McCabe and Smith, Equation 29.48, p. 1040, 7th Edition
Where: J = permeate flux
= mass transfer coefficient
C1 = concentration of EA at retentate
Cs = concentration of EA at feed
For Cs (from material balance):
For C1:
368
Table: Conversion factors for Permeate flux
m/s m/h L/m2-h Gal/ft2-day
2.78 x 10-7 10-3 1 0.589
4.72 x 10-7 1.698 x 10-3 1.698 1
369
To solve for Permeability (Qm):
Unit Operations of Chemical Engineering, McCabe and Smith, Equation 30.49, p.
1037, 5th Edition:
Where:
J = permeate flux
Qm = membrane permeability
ΔP = transmembrane pressure
Transmembrane Pressure (ΔP):
Using Raoult’s Law:
At feed:
At permeate:
370
Permeability (Qm):
Unit Operations of Chemical Engineering, McCabe and Smith, Equation 30.49, p.
1037, 5th Edition:
To solve for Area of the Membrane:
Operating time: 110 min 1.83 h ; (from Time-Dependence of Pervaporation
Performance for the Separation of Ethanol/Water Mixtures through Polyvinyl
Alcohol Membrane, by Gewei Li, Wei Zhang, Juping Yang, Xinping Wang)
371
Module Design:
Using commercially available MO 63G_I10HD V Berghof HyperFlux Tubular
Module from Berghof Filtration and Plant Engineering:
ID = 0.0103 m
L = 3 m
l =
Amodule = 12.2 m2
To Solve for Number of Modules:
To solve for Pressure Drop along Module:
372
From Berghof HyperFlux Tubular Module Data Sheet:
where:
Pressure Drop along Module = [kPa]
v =Cross Flow Velocity [m/s]
L = Module Length [m]
373
TYPE OF PUMP:
Based on Membrane Filtration Handbook, the recommended pump for
operating pressures up to 15 bar is a centrifugal pump made of stainless steel. It is
also compatible with a wide range of capacities including .
To solve for Power Requirement:
From ChE Handbook 7th Edition, p. 10-23 Equation 10-50:
Where: H =
Q =
For a pump efficiency of 70%, the actual power is:
374
CHAPTER VII
COST ESTIMATION
375
CHAPTER VII
COST ESTIMATION
I. INTRODUCTION
A project to be feasible must present a process that yields a profit. The
different types of cost involved in manufacturing processes should be studied well
so that the proposal will be acceptable. It is very important to estimate the total
expenses and the total revenue for a project that has a small amount of investment
but has a large amount of profit thereafter. The main goal is to maximize the profit
but not at the expense of the quality. Large amount of capital is required to
purchase the necessary equipments, land and service facilities, as well as piping
and process controllers, for a plant to operate. Herewith, the cost estimation
presents the detailed estimation in establishing a feasible Ethyl Acrylate
Manufacturing Plant which uses glycerol as major raw material. Detailed
computations of investment cost and operational cost were shown here.
A. Total Capital Investment
For a plant capacity of 5,700 MT/year, operating at 24 hours a day and 300
days a year, Total Capital Investment amounts to about PhP 331.43 M. The Fixed
Capital Investment is determined from the Direct Capital Investment which
includes 15.95% (PhP 52.87 M) purchased equipment delivered, 7.50% (PhP
376
24.85 M) installation, 5.74% (PhP 19.03 M) instrumentation and control, 10.85%
(PhP 35.95 M) piping system, 2.87% (PhP 9.52 M) building, 1.75% (PhP 5.82 M)
electrical system, 1.60% (PhP 5.29 M) yard improvement and 11.17% (PhP 37.01
M) service facilities. The Fixed Capital Investment (FCI) which represents the
amount necessary for the complete cost and installation of the process equipment
is computed based on the five major equipments being designed in the previous
chapter, namely: dehydration reactor, heat exchanger, absorption column,
esterification reactor and pervaporator. It is assumed that the cost of these five
equipments represent 45.45 percent of the total equipment cost of the entire plant.
Also, the working capital that is necessary to finance the plant operations is
computed and added to the fixed capital investment to get the Total Capital
Investment.
Thus, in this design:
Fixed Capital Investment = PhP 266,474,677.25
Working Capital = PhP 64,952,672.24
Total Capital Investment = PhP 331,427,349.49
377
B. Total Production Cost
It is then necessary to determine the total production cost per kilogram of
the product to see if the given design will yield a considerable amount of profit.
The total production cost is determined from the manufacturing cost which
includes the variable production cost, fixed charges, and plant overhead cost, and
the general expenses.
Manufacturing Cost = PhP 45.73/kg EA
General Expenses = PhP 9.48/kg EA
Total Production Cost = PhP 55.21/kg EA
378
Equations:
Fixed Capital Investment (FCI) = Direct Production Cost + Indirect Production
Cost
(Plant Design and Economics for Chemical Engineers, Peters et. al., 5th ed.,
p.233)
Total Capital Investment = Fixed Capital Investment + Working Capital
(Plant Design and Economics for Chemical Engineers, Peters et. al., 5th ed.,
p.232)
A. Manufacturing Cost = Direct Production Cost + Fixed Charges + Plant
Overhead Cost
(Plant Design and Economics for Chemical Engineers, Peters et. al., 5th ed.,
p.262)
B. Total Production Cost = Manufacturing Cost + General Expenses
(Plant Design and Economics for Chemical Engineers, Peters et. al., 5th ed.,
p.259)
C. Marshall and Swift Equipment Cost Index
From Chemical Engineering Journal, April 2012 issue
MSI for Process Equipment (4th Quarter 2011) = 1,597.70
379
MSI for Process Equipment (2002) = 1,104.20
From Plant Design and Economics for Chemical Engineers by Peters and
Timmerhaus, 5th Edition, Table 6-2, page 238
MSI for Process Equipment (2000) = 1,089.00
D. From Manila Bulletin, August 15, 2012
1 US$ = PhP 41.94 ≈ PhP 42.00
380
II. ESTIMATION OF CAPITAL INVESTMENT
Plant Capacity : 5,700 MT /yr
Plant Operation : 24 hrs /day
Dollar Exchange : US$ 1.00 ≈ PhP 42.00
% COST (PhP) EXHIBIT
A. Direct Costs
Purchased Equipment Delivered 15.95 52,871,959.77 A
Installation 7.50 24,849,821.09 B
Instrumentation and Control 5.74 19,033,905.52 C
Piping System 10.85 35,952,932.65 D
Building 2.87 9,516,952.76 E
Electrical System 1.75 5,815,915.58 F
Yard Improvement 1.60 5,287,195.98 G
Service Facilities 11.17 37,010,371.84 H
TOTAL DIRECT COSTS 57.43 190,339,055.18
B. Indirect Costs
Engineering and Supervision 5.26 17,447,746.73 I
Construction Expenses 6.54 21,677,503.51 J
Legal Expenses 0.64 2,114,878.39 K
Constructor’s Fee 3.51 11,631,831.15 L
Contingency 7.02 23,263,662.30 M
TOTAL INDIRECT COSTS 22.97 76,135,622.07
FIXED CAPITAL INVESTMENT 80.40 266,474,677.25
WORKING CAPITAL 19.60 64,952,672.24 N
TOTAL CAPITAL INVESTMENT 100.00 331,427,349.49
381
III. ESTIMATION OF PRODUCT COST
Plant Capacity : 5,700 MT /yr
Plant Operation : 24 hrs /day
Dollar Exchange : US$ 1.00 ≈ PhP 42.00
% COST PRODUCTION
(PhP/kg EA)
EXHIBIT
I. MANUFACTURING COST
A. Direct Production Cost AA
Raw Material 59.05 32.60
Operating Labor 0.66 0.37
Direct Supervisory and Clerical Labor 0.10 0.06
Utilities 9.09 5.02
Maintenance and Repair 5.08 2.80
Operating Supplies 0.76 0.42
Laboratory Charges 0.10 0.06
TOTAL DIRECT PRODUCTION
COST
74.85 41.32
B. Fixed Charges BB
Depreciation 1.77 0.9764
Local Taxes 2.12 1.17
Insurance 0.59 0.33
TOTAL FIXED CHARGES 4.48 2.47
C. Plant Overhead Cost 3.51 1.94 CC
MANUFACTURING COST 82.83 45.73
II. GENERAL EXPENSES DD
Administrative Cost 1.17 0.65
Distribution and Marketing 11.00 6.07
Research and Development 5.00 2.76
GENERAL EXPENSES 17.17 9.48
TOTAL PRODUCTION COST 100.00 55.21
382
EXHIBIT A
TOTAL COST OF PURCHASED EQUIPMENT
Schedule
Dehydration Reactor PhP 10,838,176.18 A-1
Heat Exchanger PhP 32,474.30 A-2
Absorption Column PhP 2,931,380.70 A-3
Esterification Reactor PhP 2,370,071.18 A-4
Pervaporator PhP 3,052,142.21 A-5
Total PhP 19,224,244.57
Assuming that the cost of five equipment is 45.45% of the Total equipment cost,
(Basis of Assumption: We designed 5 (1 unit of R-1, 1 unit of H-1, 1 unit of A-1, 1
unit of R-3 and 1 unit of PV-1) out of 11 or about 45.45 % of the total equipment
but most of them are the expensive ones)
Total Cost of Purchased Equipment (Delivered)
Using 25% delivery cost
383
SCHEDULE A-1
Equipment : DEHYDRATION REACTOR
Equipment Code : R-1
Type : Fixed Bed Reactor
Material of Construction : S31600
• From Equipment Design
Design Capacity
Diameter = 1.1 m
Height = 4.30 m
Mass of Catalyst Bed = 8,869.57 kg
Composition: 9.3 wt% WO3; 90.7 wt% ZrO2
• Present cost
Cost of Vessel (Packed):
For Stainless Steel:
For Diameter = 1.1 m
(PD & E Peters & Timmerhaus 5th Ed.; Figure 15-16; p. 796)
384
For Diameter= 1.1 m; Height = 4.30 m
Cost of Catalyst Bed:
For WO3:
For ZrO2:
(ProChem, Inc., Retrieved from http://www.prochemonline.com/)
Present FOB Cost of R-1 in Philippine Currency:
= PhP 10,838,176.18
385
SCHEDULE A-2
Equipment : HEAT EXCHANGER
Equipment Code : H-1
Type : Shell and Tube Heat Exchanger
Material of Construction
Shell : G10200
Tube : S50200
• From Equipment Design
Tube Diameter = 0.016 m
Heating Surface = 4.70 m2
Present cost
For Tube Diameter = 0.016 m
(PD & E Peters & Timmerhaus 5th Ed.; Figure 14-21; p. 683)
For Carbon Steel Shell & Stainless Steel Tube:
Material Adjustment Factor = 1.70
(PD & E Peters & Timmerhaus 5th Ed.; Figure 14-19; p. 682)
386
For Heating Surface = 4.70 m2
Present FOB Cost of H-1 in Philippine Currency:
= PhP 32,474.30
387
SCHEDULE A-3
Equipment : ABSORPTION COLUMN
Equipment Code : A-1
Type : Tray Column
Material of Construction
Tray : S31600
Column : S31600
• From Equipment Design
Diameter = 1.5 m
Height = 3.5 m
No. of Trays = 5
Present cost
Cost of Column:
For Height = 3.5 m
Diameter = 1 m
388
For 316 Stainless Steel:
Material Adjustment Factor = 3.0
(PD & E Peters & Timmerhaus 5th Ed.; Figure 15-11; p. 793)
Cost of Trays:
For Sieve Tray (Stainless Steel):
Diameter = 1.5 m
For 5 trays:
Quantity Factor = 2.30
(PD & E Peters & Timmerhaus 5th Ed.; Figure 15-11; p. 793)
389
Present FOB Cost of A-1 in Philippine Currency:
= PhP 2,931,380.70
390
SCHEDULE A-4
Equipment : ESTERIFICATION REACTOR
Equipment Code : R-3
Type : Stirred Reactor
Material of Construction : S31600
• From Equipment Design
Power Consumption = 13 HP
Present cost
For Double-arm sigma mixers:
Power Consumption = 13 HP
(PD & E Peters &Timmerhaus 5th Ed.; Figure 13-14; p. 627)
Present FOB Cost of R-3 in Philippine Currency:
= PhP 2,370,071.18
391
SCHEDULE A-5
Equipment : PERVAPORATOR
Equipment Code : PV-1
Type : Tubular
Material of Construction
Membrane Material : Polyvinyl Alcohol
Module : Fiber Reinforced Plastic (FRP), Resin
• From Equipment Design
Total Membrane Area = 381.30 m2
Present cost
For Membrane Area =1 m2
Typical investment in a complete system, including pumps, tubes,
membranes and controls
(Membrane Filtration Handbook; Table 37; p. 117)
392
Present FOB Cost of PV-1 in Philippine Currency:
=PhP 3,052,142.21
393
EXHIBIT B
Installation Cost
Installation of process equipment includes the cost of labor. The
foundations support platforms, constructions related expenses and other factors
related to the erection of the purchase equipment are part of the estimation of the
installation cost.
47% (Purchased Equipment Delivered) from P&T, Table 6-9, Fluid
Processing Plant, p. 251
Installation Cost = 0.47 (PhP 52,871,959.77)
= PhP 24,849,821.09
394
EXHIBIT C
Instrumentation and Control Cost
Instrumentation and control involves the installation labor cost and
purchase of auxiliary machines used for the control of equipment. Auxiliary
equipment involves the pressure and temperature and flow controller of the plant.
36% (Purchased Equipment Delivered) from P&T, Table 6-9, Fluid
Processing Plant, p. 251
Instrumentation and Control Cost = 0.36 (PhP 52,871,959.77)
= PhP 19,033,905.52
395
EXHIBIT D
Piping (Installed)
The piping cost covers the cost of labor in its installation, cost of pipes,
valves, fittings and all other piping related requirement for the piping erection of
the facility.
68% (Purchased Equipment Delivered) from P&T, Table 6-9, Fluid
Processing Plant, p. 251
Piping, Installed = 0.68 (PhP 52,871,959.77)
= PhP 35,952,932.65
396
EXHIBIT E
Buildings (Including Services)
Cost of buildings includes the cost of installation for the erection of
administrative offices the cost of plumbing, heating, lighting ventilation and other
similar services.
18% (Purchased Equipment Delivered) from P&T, Table 6-9, Fluid
Processing Plant, p. 251
Buildings (Including Services) = 0.18 (PhP 52,871,959.77)
= PhP 9,516,952.76
397
EXHIBIT F
Electrical Systems (Installed)
The electrical system consists of four major components namely, power
wiring, lighting, transformation and service and instrument and control wiring.
11% (Purchased Equipment Delivered) from P&T, Table 6-9, Fluid
Processing Plant, p. 251
Electrical Systems (Installed) = 0.11 (PhP 52,871,959.77)
= PhP 5,815,915.58
398
EXHIBIT G
Yard Improvement
Yard improvements includes the fencing, grading, roads, sidewalks,
railroad sidings, landscaping and any other similar items related to yard
improvements.
10% (Purchased Equipment Delivered) from P&T, Table 6-9, Fluid
Processing Plant, p. 251
Yard Improvement = 0.10 (PhP 52,871,959.77)
= PhP 5,287,195.98
399
EXHIBIT H
Service Facilities
This includes the utilities for supplying steam, water, power, and fuel for
the chemical processes and operations. Waste disposal, fire protection and
miscellaneous service items such as shops, clinics or first aid quarters and
cafeterias require capital investment that are included under general heading of
service facilities.
70% (Purchased Equipment Delivered) from P&T, Table 6-9, Fluid
Processing Plant, p. 251
Service Facilities = 0.70 (PhP 52,871,959.77)
= PhP 37,010,371.84
400
EXHIBIT I
Engineering and Supervision
The cost for construction design and engineering, including internal or
licensed software, computer-aided drafts, purchasing, accounting, travel, and the
plant supervisory services must be part of the capital investment.
33% (Purchased Equipment Delivered) from P&T, Table 6-9, Fluid
Processing Plant, p. 251
Engineering and Supervision = 0.33 (PhP 52,871,959.77)
= PhP 17,447,746.73
401
EXHIBIT J
Construction Expenses
This includes construction labor and other construction related expenses,
construction tools and rentals, construction payroll, construction tariffs, insurance
and permits, miscellaneous equipment installation and other fees related to
construction process.
41% (Purchased Equipment Delivered) from P&T, Table 6-9, Fluid
Processing Plant, p. 251
Construction Expenses = 0.41 (PhP 52,871,959.77)
= PhP 21,677,503.51
402
EXHIBIT K
Legal Expenses
Legal costs refer mostly to the processing of land purchase, equipment
purchase and construction contracts. Understanding and proving compliance with
the government, environmental and safety requirements constitute major sources
of legal cost.
4% (Purchased Equipment Delivered) from P&T, Table 6-9, Fluid
Processing Plant, p. 251
Legal Expenses = 0.04 (PhP 52,871,959.77)
= PhP 2,114,878.39
403
EXHIBIT L
Contractor’s Fee
The contractor’s fee is the payment involve for the construction contract
and other related charges.
22% (Purchased Equipment Delivered) from P&T, Table 6-9, Fluid
Processing Plant, p. 251
Contractor’s Fee = 0.22 (PhP 52,871,959.77)
= PhP 11,631,831.15
404
EXHIBIT M
Contingency
A contingency amount is included in the estimation of the project cost in
recognition of the fact of the occurrence in the unexpected events and charges that
inevitable increase the cost of the project. Events such as storms, flood,
transportation accidents, strikes, price changes, errors of the estimation and
unforeseen expenses may occur as such, it should have its own appropriation.
44% (Purchased Equipment Delivered) from P&T, Table 6-9, Fluid
Processing Plant, p. 251
Contingency = 0.44 (PhP 52,871,959.77)
= PhP 23,263,662.30
405
EXHIBIT N
WORKING CAPITAL
The Working Capital for an Industrial plant consist of the total amount of
money invested in (1) Raw Materials (2) Finished Products (3) Cash on Hand for
Operating Expenses (4) Accounts Receivable (5) Accounts and Taxes Payable.
Working Capital = RAW MATERIALS + LABOR COST + UTILITIES
Schedule
Raw Material PhP 55,744,433.64 N-1
Labor PhP 627,210.00 N-2
Utilities
A. Water PhP 655,365.47 N-3
B. Steam PhP 6,886,730.34 N-4
C. Electricity PhP 1,038,932.79 N-5
Total PhP 64,952,672.24
TOTAL WORKING CAPITAL = PhP 64,952,672.24
406
SCHEDULE N-1
RAW MATERIAL
Raw material that is used in the process is one of the major costs in a
production operation. Raw materials refer in general to those materials that are
directly consumed in making the final product; this includes chemical reactants,
and constituents and additives included in the product.
Crude Glycerol
Price: PhP 9.03/kg glycerol
(PHP 12.90/kg for Refined Glycerol, assume price of raw glycerol is 30%
lower.)
Supplier: ChemSynergy Asia, Inc. (Manufacturer) – Philippines
Cost of Glycerol:
= PhP 27,631,800.00
Ethanol (99.9 wt %)
Price: PhP 35.56/kg ethanol
(Reference: Platts Energy News, Prices & Data; Lower domestic output
from Philippines pushes Asian ethanol prices higher, Retrieved from
http://www.
platts.com/RSSFeedDetailedNews/RSSFeed/Petrochemicals/7948330)
Cost of Ethanol:
= PhP 28,112,633.64
Total Raw Materials Cost = PhP 55,744,433.64
407
SCHEDULE N-2
Operating Labor
Estimating labor requirements as a function of plant capacity is based on
adding the various principal processing steps on the flow sheet. In this method, a
process step is defined as any unit operation or unit process, unit process, or
combination thereof that takes place in one or more units of grinding, extracting,
fermenting, filtering, distilling etc.
Plant Capacity per day = 19,000 kg Ethyl Acrylate
Using Fig. 6 – 9 Peters & Timmerhaus, 5th ed. (Line C: Large Equipment, highly
automated or fluid processing only):
Number of Process steps = 6
(Reference: http://www.nwpc.dole.gov.ph/pages/ncr/cmwr_table.html)
Operating Labor = PhP 627,210.00
408
SCHEDULE N-3
UTILITIES
The cost for utilities, such as steam, electricity and cooling water varies
widely depending on the amount needed plant location and source.
Water
Cost: PhP 20.16/m3 H2O
(Reference: http://122.54.214.222/waterrates/RatesTable.asp)
From Material Balance and Energy Balance:
Equipment Water Required/day
Heat Exchanger (H-1) 28,432.74 kg
Absorption Column (A-1) 16,000.00 kg
Oxidation Reactor (R-2) 184,972.63 kg
Condenser (C-1) 81,722.91 kg
Heat Exchanger (H-2) 7,708.75 kg
Condenser (C-2) 42,365.28 kg
Total 361,202.31 kg
409
SCHEDULE N-4
UTILITIES
Steam
From Material and Energy Balance:
Equipment Steam Required/day
Glycerol Preheater (B-1) 49,776.18 kg
Acrolein Preheater (B-2) 1,955.53 kg
Esterification Reactor (R-3) 1,040.17 kg
Total 52,771.88 kg
Depreciable Boiler Cost
For Steam capacity of 1 kg/s and pressure of 1,825 kPa:
(PD & E Peters & Timmerhaus 5th Ed.; Figure B-3; p. 892)
For Industrial Steam Generation,
(PD & E Peters & Timmerhaus 5th Ed.; Table 7-8; p. 310)
410
Power Generation Cost
For Capacity = 1 kg/s
(Efficiency = 60%)
(Reference: Hurst Boiler and Welding Company, Inc.)
Meralco Rate: PhP 10.8578/kw-hr (Industrial consumer)
(Reference: http://meralco.com.ph/pdf/newsandupdates/2012
/NW00112.pdf)
Fuel Cost
For Bunker C Fuel Oil:
(Reference: http://www.engineeringtoolbox.com/fuel-oil-combustion-
values-d_509.html)
411
(Reference: Pilipinas Shell Petroleum Corporation)
From Material and Energy Balance:
Then,
412
SCHEDULE N-5
Electricity
Meralco Rate: PhP 10.8578/kw-hr (Industrial consumer)
(Reference: http://meralco.com.ph/pdf/newsandupdates/2012
/NW00112.pdf)
1. Dehydration Reactor: P = 1.5 HP ≈ 1.1185 kW
Operating Time = 24 hrs/day
= PhP 26,232.01
2. Heat Exchanger: P = 4 HP ≈ 2.9828 kW
Operating Time = 24 hrs/day
= PhP 69,955.16
3. Absorption Column: P = 1.5 HP ≈ 1.1185 kW
Operating Time = 24 hrs/ day
= PhP 26,232.01
413
4. Esterification Reactor: P = 13 HP ≈ 9.6941 kW
Operating Time = 24 hrs/day
= PhP 227,354.25
5. Pervaporator: P = 7 HP ≈ 5.2199 kW
Operating Time = 24 hrs/day
= PhP 122,421.52
Assuming that the Electricity Cost of five equipments is 45.45% of the Total
Electricity Cost,
414
EXHIBIT AA
DIRECT PRODUCTION COST
Cost (PhP) / kg EA Schedule
Raw Material PhP 32.60 AA-1
Operating Labor PhP 0.37 AA-2
Direct Supervisory and Clerical
Labor
PhP 0.06 AA-3
Utilities PhP 5.02 AA-4
Maintenance and Repair PhP 2.80 AA-5
Operating Supplies PhP 0.42 AA-6
Laboratory Charges PhP 0.06 AA-7
Total PhP 41.32
TOTAL DIRECT PRODUCTION COST = PhP 41.32/kg EA
415
SCHEDULE AA-1
Raw Material
Crude Glycerol
Price: PhP 9.03/kg glycerol
(PhP 12.90/kg for Refined Glycerol, assume price of raw glycerol is 30%
lower.) Supplier: ChemSynergy Asia, Inc. (Manufacturer) – Philippines
Cost of Glycerol:
= PhP 16.16/ kg EA
Ethanol (99.9 wt %)
Price: PhP 35.56/kg ethanol
(Reference: Platts Energy News, Prices & Data; Lower domestic output
from Philippines pushes Asian ethanol prices higher, Retrieved from
http://www.platts.com/RSSFeedDetailedNews/RSSFeed/Petrochemicals/794
8330)
Cost of Ethanol:
= PhP 16.44/ kg EA
Total Raw Materials Cost = PhP 32.60/ kg EA
416
SCHEDULE AA-2
Operating Labor
Plant Capacity per day = 19,000kg Ethyl Acrylate
Using Fig. 6 – 9 Peters & Timmerhaus, 5th ed. (Line C: Large Equipment,
highly automated or fluid processing only)
Number of Process steps = 6
(http://blog.pinoydeal.ph/pinoydeal/2011-minimum-wage-rates)
Operating Labor = PHP 0.37/kg EA
417
SCHEDULE AA-3
Direct Supervisory and Clerical Labor
In a manufacturing operation, a certain amount of direct supervisory and
clerical assistance is always required. The necessary amount of this type of labor is
closely related to the total amount of operating labor, complexity of the operation,
and product quality standards. The cost for direct supervisory and clerical labor
averages about 15 percent of the cost for operating labor.
15% (Operating Labor) from Peter and Timmerhaus, 5th Ed.
418
SCHEDULE AA-4
Utilities
A. Total Water Cost PhP 0.38/kg EA
B. Total Steam Cost PhP 4.03/kg EA
C. Total Electricity Cost PhP 0.6076/kg EA
Total Utilities Cost PhP 5.02/kg EA
A. Total Water Cost
Cost: PhP 20.16/m3 H2O
(Reference: http://122.54.214.222/waterrates/RatesTable.asp)
From Material and Energy Balance
Equipment Water Required/day
Heat Exchanger (H-1) 28,432.74 kg
Absorption Column (A-1) 16,000.00 kg
Oxidation Reactor (R-2) 184,972.63 kg
Condenser (C-1) 81,722.91 kg
Heat Exchanger (H-2) 7,708.75 kg
Condenser (C-2) 42,365.28 kg
Total 361,202.31 kg
419
420
B. Total Steam Cost
Cost: PhP 1.45/kg steam
(Steam Cost Computation, refer to page 298)
From Energy Balance:
Equipment Steam Required/day
Glycerol Preheater (B-1) 49,776.18 kg
Acrolein Preheater (B-2) 1,955.53 kg
Esterification Reactor (R-3) 1,040.17 kg
Total 52,771.88 kg
421
C. Total Electricity Cost
Meralco Rate: PhP 10.8578/kw-hr (Industrial consumer)
(Reference: http://meralco.com.ph/pdf/newsandupdates/2012/
NW00112.pdf)
1. Dehydration Reactor: P = 1.5 HP ≈ 1.1185 kW
Operating Time = 24 hrs/day
= PhP 0.0153/kg EA
2. Heat Exchanger: P = 4 HP ≈ 2.9828 kW
Operating Time = 24 hrs/day
= PhP 0.0409/kg EA
3. Absorption Column: P = 1.5 HP ≈ 1.1185 kW
Operating Time = 24 hrs/ day
= PhP 0.0153/kg EA
422
4. Esterification Reactor: P = 13 HP ≈ 9.6941 kW
Operating Time = 24 hrs/day
= PhP 0.1330/kg EA
5. Pervaporator: P = 7 HP ≈ 5.2199 kW
Operating Time = 24 hrs/day
= PhP 0.0716/kg EA
Assuming that the Electricity Cost of three equipments is 45.45% of the Total
Electricity cost,
423
SCHEDULE AA-5
MAINTENANCE AND REPAIR
Annual cost for equipment maintenance and repairs may range from 2% –
20% of the equipment cost. Charges for plant buildings average 3% - 4% of the
building cost. The total plant cost per year for maintenance and repairs ranges
from 2% to 10% of the fixed capital investment.
6% (Fixed Capital Investment) from Peter and Timmerhaus, 5th Ed.
424
SCHEDULE AA-6
Operating Supplies
In any manufacturing operation, many miscellaneous suppliers are needed
to keep the process functioning efficiently. These are not considered raw materials
or maintenance and repair material but as operating supplies. Some of these items
include charts, lubricants, test chemicals and custodial supplies. The annual cost
for these types is about 15% of the total cost of maintenance and repair.
15% (Maintenance and Repair) from Peter and Timmerhaus, 5th Ed.
425
SCHEDULE AA-7
Laboratory Charges
These include the costs of laboratory tests for control of operations and for
product quality control. This cost may be taken as 15% of the operating labor.
15% (Operating Labor) from Peter and Timmerhaus, 5th Ed.
426
EXHIBIT BB
FIXED CHARGES
Cost (PhP) / kg EA Schedule
Depreciation PhP 0.98 BB-1
Local Taxes PhP 1.17 BB-2
Insurance PhP 0.33 BB-3
Total PhP 2.47
TOTAL FIXED CHARGES = PhP 2.47/kg EA
427
SCHEDULE BB-1
Depreciation
The equipment, buildings and other material objects comprising a
manufacturing plant require an initial investment that must be paid back and this is
done by charging depreciation as a manufacturing expense. Depreciation rates are
very important in determining the amount of income tax.
Using Straight-Line Method:
Where: V = the original investment in the property at the start of the
recovery period
= the total purchase equipment cost delivered
= PhP 52,871,959.77
n = length of the straight-line recovery period
= 9.5 years, Manufacture of chemicals and allied products
(Table 7-8 of Peters and Timmerhaus 5th ed., p. 310)
428
SCHEDULE BB-2
Local Taxes
The magnitude of local property taxes depends on the particular locality of
the plant and the regional laws. Annual property taxes for plants in highly
populated areas are ordinarily in the range of 2% - 4% of the fixed capital
investment.
2.5% (Fixed Capital Investment) from Peter and Timmerhaus, 5th Ed.
429
SCHEDULE BB-3
Insurance
Insurance rate depends on the type of process being carried out in the
manufacturing operation and on the extent of available protection facilities. These
rates amount to about 0.7% of the fixed capital investment per year.
0.7% (Fixed Capital Investment) from Peter and Timmerhaus, 5th Ed.
430
EXHIBIT CC
PLANT OVERHEAD COST
In plant overhead costs, the expenditure required for routine plant services.
Non – manufacturing machinery, equipment, and buildings are necessary for many
of the general plant services, and the fixed charges and direct cost for these items
are part of the plant overhead cost.
60% (O.L. + Supervisory + M and R) from Peter and Timmerhaus, 5th Ed.
431
EXHIBIT DD
GENERAL EXPENSES
General expenses constitutes mainly of indirect cost on production. It
includes Administrative Costs, Product distribution and as well as expenses for
Research and development.
From Plant Design and Economics by Peters and Timmerhaus, General
expenses comprise for the 15-25% of the total product cost.
Cost (PhP) / kg EA Schedule
Administrative Cost PhP 0.65 DD-1
Distribution and Marketing PhP 6.07 DD-2
Research and Development PhP 2.76 DD-3
Total PhP 9.48
TOTAL GENERAL EXPENSES = PhP 9.48/kg EA
432
SCHEDULE DD-1
Administrative Cost
Salaries and wages for administrator, secretaries, accountants, computer
support staff, engineering and legal personnel are part of the administrative
expenses, along with cost for office supplies and equipment, outside
communications, administrative buildings and other overhead items related to
administrative activities.
20% (O.L. + Supervisory + M and R) from Peter and Timmerhaus, 5th Ed.
433
SCHEDULE DD-2
Distribution and Marketing Cost
Salaries, wages, supplies and other expenses for sales offices, commissions
and travelling expenses for sales representatives, shipping expenses, cost of
containers advertising expenses and technical sales services are included in this
category.
11% (Total Product Cost) from Peter and Timmerhaus, 5th Ed.
TPC = Manufacturing Cost + Administrative Cost + Distribution and
Marketing + Research and Development
434
SCHEDULE DD-3
Research and Development
Research and development costs include salaries and wages for all
personnel directly connected with this type of work, fixed and operating expenses
for all machinery and equipment involved, cost for materials and supplies and
consultant’s fee.
5% (Total Product Cost) from Peter and Timmerhaus, 5th Ed.
435
CHAPTER VIII
ECONOMIC
EVALUATION
436
CHAPTER VIII
ECONOMIC EVALUATION
I. INTRODUCTION
Whenever a new project is to be considered, it requires a commitment of
capital funds also known as investment. Whenever investment is to be made to a
certain project, it is important to evaluate the profitability of the project since the
main purpose of the investments is to generate income. Total profit alone cannot
be used as basis whether the project is profitable or not. If the goal of an
investment is to merely earn a profit, any investment that gives profit would be
acceptable regardless of how much and how long the return of the investment
would be. The objective of the profitability analysis is to give a measure of the
attractiveness or possibility of the project for possible course of action. It is
therefore important to consider the profitability analysis method to be used in
order to give a reliable measure of the economic feasibility of the project.
There are various methods that can be used in determining the profitability.
These methods are divided into those that consider the time value of money and
those that are not. Methods that do not consider the time value of money includes:
a) Rate of Return on Investment (ROI), b) Payback Period, c) Net Return. The
methods that consider the time value of money are a) Discounted Cash Flow Rate
of Return, and b) Net Present Worth. In this study, the methods used in
437
profitability analysis are the Rate of Return on Investment and Net Present Worth.
Break Even analysis is also presented on the latter part of this chapter.
II. Analysis and Interpretation
At present time, there is no existing plant of Ethyl Acrylate in the country.
For the purpose of economic evaluation of the project, the international market
price is considered. The international market price of ethyl acrylate (Reference:
ICIS Pricing) is US$ 1,810 per ton or nearly PhP 83.81 per kilogram. The Total
Production Cost (TPC) for the proposed Ethyl Acrylate plant is found to be PhP
55.21 per kilogram. Since the Total Production Cost is lower than the selling price
of the competitor, it is safe to say that the proposed plant will be profitable. Also,
because the product is imported, 10-15% additional cost will be added to the price.
A selling price of PhP 75.00 per kilogram of Ethyl Acrylate is therefore proposed.
It is 10.50% lower than the international market price.
A. Rate of Return on Investment
Using the Rate of Return on Investment as the first method of analysis, we
can be able to determine how fast the return on investment would be. Higher ROI
value is advantageous for the project. Also, the higher the value of ROI, the better
is the project because the faster will be the return on investment of the project.
For a capital investment of PhP 331.43 M and a selling price of PhP 75.00
per kilogram of Ethyl Acrylate, the expected net annual profit amounts to PhP
438
112.82 M. Current loan rate is 18.05% (Reference: Bangko Sentral ng Pilipinas).
In this case, the rate of return on investment is 34.04%, which means that the
project is still profitable but the investment cannot be recovered immediately in
one year of operation of the project.
B. Net Present Worth
In the second method of analysis which is the Net Present Worth method,
the profitability of the project can be evaluated by comparing the net present cash
inflows to the net present outflows. If the net present cash inflows or the net
present worth equivalent of annual profit is higher than the net present worth of
cash outflows or investments, then the net present worth of the project would be
higher than zero indicating that the project is economically profitable. The higher
the value of net present worth the better and more profitable the project is.
For this project, the estimated net annual profit is equal to PhP 112.82 M.
Using 20 years of operation of the plant and a minimum attractive rate of return
(MARR) of 12.50% (Reference: Bangko Sentral ng Pilipinas), the calculated net
present worth of the project is PhP 485.55 M. This is a positive value indicating
that the project is profitable because the net present worth equivalent of the annual
profit is significantly higher than the present worth of investment.
439
C. Break-even Point Analysis
To determine the rate of production of the plant capacity necessary in order
to have a profit, the break-even point analysis must be considered. The production
rate that would give a gross sales equivalent to total production cost is known as
the break-even point because the net profit zero.
The break-even point can be computed by dividing the total fixed cost by
the difference of selling price and total variable cost. From the previous chapter,
the fixed cost and variable cost (Total Direct Production Cost) amounts to PhP
13.89/kg EA and PhP 41.32/kg EA, respectively. Fixed cost comprises of Fixed
Charges, Plant Overhead Cost and General Expenses.
In this case, the calculated percent break-even point is about 41.23%. This
means that the plant should always operate at a production rate higher than
41.23% of the actual plant capacity (5,700 MT EA/yr), corresponding to 2,350 MT
EA/yr, in order to have a net profit. If the plant operated at a rate lower than 2,350
MT EA/yr, the plant will not be profitable on each operation.
440
III. Conclusion
The main objective of this work is to demonstrate the economic advantage
of using glycerol as a major raw material in producing ethyl acrylate.
Based on the analysis, the project would be profitable. This is evident since
the attained net present worth equivalent of the annual profit is a positive value.
Also, the project would yield a high rate of return on investment (34.04%) which
implies that the project is worth investing for.
In conclusion, this plant design would absolutely be economically feasible.
441
IV. Detailed Computations
A. Rate of Return on Investment
Profit Estimation (Z)
Using the equation presented by Peters & Timmerhaus in Plant Design and
Economics for Chemical Engineers:
Where: n = Plant Capacity, kg/yr
Z = Net annual profit, PhP/yr
TCI = Total capital investment
The proposed market price of Ethyl Acrylate is PhP 75.00/kg EA
Plant Capacity is 5,700,000 kg/yr
TPC =PhP 55.21/kg
TCI = PhP 331,427,349.49
442
B. Net Present Worth Calculation
From Bangko Sentral ng Pilipinas, the loan interest for long term period
(more than 5 years) is 12.50%. From Plant Design and Economics for ChE by
Peters & Timmerhaus
Where: PW = present worth equivalent of net annual profit
A = net annual profit
i = annual interest rate
n = period of operation = 20 years
Estimated net annual net profit is PhP 112,821,716.88
Initial investment is PhP 331,427,349.49
443
C. Break-even Point (BEP)
At break-even point, net annual profit (Z) = 0
Where: F = Fixed Cost, PhP/ yr
= Fixed Charges + Plant Overhead Cost + General Expenses
S = Selling Price, PhP/ kg = PhP 75.00/kg EA
V = Variable cost, PhP/kg
From Cost Estimation:
Fixed Charges = PhP 2.47/kg EA
Plant Overhead Cost = PhP 1.94/kg EA
General Expenses = PhP 9.48/kg EA
Variable Cost (Total Direct Cost) = PhP 41.32/kg EA