Manufacture of Sugar

PROJECT REPORT on

MANUFACTURE OF SUGAR FROM SUGAR CANE

Submitted in partial fulfillment for the award of the degree

of

BACHELOR OF TECHNOLOGY

in

CHEMICAL ENGINEERING

by

RAJASEKAR .V (10704014)

SATHIYA NARAYANAN .S (10704017)

under the guidance of

Mr. M. MAGESH KUMAR, M.Tech., (Senior Lecturer, Department of Chemical Engineering)

FACULTY OF ENGINEERING AND TECHNOLOGY SRM UNIVERSITY

(under section 3 of UGC Act,1956) SRM Nagar, Kattankulathur – 603 203

Kancheepuram Dist.

May 2008

BONAFIDE CERTIFICATE

Certified that this project report on “MANUFACTURE OF SUGAR

FROM SUGAR CANE ” is the bonafide work of “RAJASEKAR .V

(10704014) and SATHIYA NARAYANAN .S (10704017)” who carried

out the project work under my supervision.

HEAD OF THE DEPARTMENT INTERNAL GUIDE Date:

EXTERNAL EXAMINER INTERNAL EXAMINER DATE :

ACKNOWLEDGEMENT

We are extremely thankful to Dr.R.KARTHIKEYAN, B.E., PhD, Professor

and Head, School of Chemical Engineering, S.R.M University, for permitting us to

venture on this project and providing us with good support and guidance.

We would like to thank Mr. M.MAGESH KUMAR, B.Tech, .M.Tech,

Faculty, School of Chemical Engineering, S.R.M University, for his encouragement

and guidance at all stages of this project.

We extend our sincere thanks to all the staff members of the School of

Chemical Engineering, S.R.M University, for their support and assistance.

ABSTRACT

This project deals with the manufacture of sugar from sugarcane.

Since the demand for sugar has been increasing day by day. A detailed

process Flow sheet, Material Balance, Energy Balance have been done. A

detailed Design of equipments, Cost Estimation of plants, Plant layout

and Safety aspects have been discussed.

CONTENTS

S. NO CONTENTS PG NO

1 Introduction 1

2 Properties 5

3 Process description 8

4 Material balance 16

5 Energy balance 25

6 Equipment design 37

7 Process control 46

8 Pollution control 49

9 Cost estimation 56

10 Plant location and site selection 67

5

1.INTRODUCTION

6

INTRODUCTION

Sugar industry is one of the most important agro-based industries in India and

is highly responsible for creating significant impact on rural economy in particular

and country’s economy in general. Sugar industry ranks second amongst major agro-

based industries in India. As per the Government of India’s recent liberalised policy

announced on 12th December, 1986 for licensing of additional capacity for sugar

industries during 7th five-year plan, there will be only one sugar mill in a circular area

of 40 sq km. Also the new sugar mill is allowed with an installation capacity of 2500

TCD (Tonne Sugar Cane crushed per day) as against the earlier capacity norms of

1250 TCD. Similarly, the existing sugar mills with sugar cane capacity of about 3500

TCD can crush sugar cane to the tune of 5000 TCD with a condition imposed that

additional requirement of sugar cane be acquired through increased productivity and

not by expansion of area for growing sugar cane.

Cane sugar is the name given to sucrose, a disaccharide produced from the

sugarcane plant and from the sugar beet. The refined sugars from the two sources are

practically indistinguishable and command the same price in competitive

markets.However, since they come from different plants, the trace constituents are

different and can be used to distinguish the two sugars. One effect of the difference is

the odor in the package head space, from which experienced sugar workers can

identify the source.

In the production scheme for cane sugar, the cane cannot be stored for more

than a few hours after it is cut because microbiological action immediately begins to

degrade the sucrose. This means that the sugar mills must be located in the cane

fields. The raw sugar produced in the mills is item of international commerce. Able to

be stored for years, it is handled as raw material – shipped at the lowest rates directly

in the holds of ships or in dump trucks or railroad cars and pushed around by

bulldozers. Because it is not intended to be eaten directly, it is not handled as food.

The raw sugar is shipped to the sugar refineries, which are located in population

centers. There it is refined to a food product, packaged, and shipped a short distance

7

to the market. In a few places, there is a refinery near or even within a raw-sugar mill.

However, the sugar still goes through raw stage.

The principle by-product of cane sugar production is molasses. About 10 –

15% of the sugar in the cane ends up in molasses. Molasses is produced both in the

raw-sugar manufacture and also in refining. The blackstrap or final molasses is about

35 – 40% sucrose and slightly more than 50% total sugars. In the United States,

blackstrap is used almost entirely for cattle feed. In some areas, it is fermented and

distilled to rum or industrial alcohol. The molasses used for human consumption is of

a much higher grade, and contains much more sucrose.

Sugarcane characteristics:

Sugarcane contains not only sucrose but also numerous other dissolved

substances, as well as cellulose or woody fibre. The percentage of sugar in the cane

varies from 8 to 16% and depends to a great extent on the variety of the cane, its

maturity, condition of the soil, climate and agricultural practices followed. The

constituents of ripe cane vary widely in different countries and regions but fall

generally within the following limits:

Constituent Percentage range

Water 69.0 – 75.0

Sucrose 8.0 – 16.0

Reducing sugars 0.5 – 2.0

Organic matter other than sugar 0.5 – 1.0

Inorganic compounds 0.2 – 0.6

Nitrogenous bodies 0.5 – 1.0

Ash 0.3 – 0.8

Fibre 10.0 – 16.0

8

Organic matters other than sugar include proteins, organic acids,

pentosan,colouring matter and wax. Organic acids present in cane are glycolic acid,

malic acid, succinic acid and small quantity of tannic acid, butyric acid and aconitic

acid. These vary from 0.5 to 1.0% of the cane by weight. The organic compounds are

made up of phosphates, chlorides, sulphates, nitrates and silicates of sodium,

potassium, calcium,magnesium and iron chiefly. These are present from 0.2 to

0.6%.The nitrogenous bodies are albuminoid, amides, amino acids, ammonia,

xanthine bases, etc. These are present to the extent of 0.5 to 1.0%. Fibre is the

insoluble substance in the cane. Dry fibre contains about 18.0% lignin, 15% water-

soluble substances, 45% cellulose and the rest hemicellulose.The juice expressed from

the cane is an opaque liquid covered with froth due to air bubbles entangled in it. The

colour of the juice varies from light grey to dark green. Colouring matter is so

complex that very little is known about them and there is a great need for research in

this direction. ‘Colouring matters’ consist of chlorophyll, anthocyanin, saccharatin

and tannins. Canes which have been injured or which are over-ripe contain ordinarily

invert sugar as well. When severe frost damages sugarcane, all buds are killed and the

stalk split. Then the juice produced has low purity, less sucrose, high titrable acidity,

and abnormal amounts of gum, which make processing difficult and at times

impossible. Frost is generally not a very common phenomenon in Indian crops.

Insects and pests cause a greater damage. Cane juice has an acidic reaction. It has a

pH of about 5.0. The cane juice is viscous owing to the presence of colloids. The

colloids are particles existing in a permanent state of fine dispersion and they impart

turbidity to the juice. These colloids do not settle ordinarily unless conditions are

altered. The application of heat or addition of chemicals brings about flocculation or

coagulation. They may be coagulated by the action of electric current and adsorption

by sucrose attractions using porous or flocculent material. Some colloids are

flocculated easily while others do so with great difficulty. Each colloid has a

characteristic ‘pH’ at which flocculation occurs most easily. It is known as the

isoelectric point of the colloid. The cane juice is turbid owing to the presence of such

colloidal substances as waxes, proteins, pentosans, gums, starch and silica.

9

2.PROPERTIES

10

PROPERTIES

Physical properties

Molecular weight 342

Specific heat capacity 0.28 kcal/kg

Density 1.63 g/cm^3

Melting point 184 centigrade

Specific gravity 1.58056

Solubility

Temperature sucrose g/100 water

0 180.9

10 188.4

20 199.4

30 214.3

40 233.4

50 257.6

60 324.6

11

Chemical properties

Hydrolysis

Sucrose is easily hydrolyed in the presence of hydrogen ion,ammonium ion

and certain enzymes all acting as catalysts to a mixture of d-glucose and d-fructose

called”invert suger”because of a reversal in direction of optical rotation.

Oxidation

Vigorous oxidation of sucrose with strong nitric acid produes equimolar

quantities of oxalic acid and tartanic acid.when the oxidation with nitric acid is carried

out in the presence of sodium metavanadate.

Hydrogenation

In the presence of raney-nickel catalyst inverted sucroses is hydrogenated to a

mixture to a sorbitol and d-mannitol.

Hydrogenolysis

Under more drastic conditions the sugar chain are severed and good yields of

glycerol and propylene glycol are formed.

Alkaline degradation

Sucroses autoclaved with aqueous calcium hydroxide yields up to 70%of

lactic acid.

Acid degradation

Hot mineral convert sucrose to 5-hydroxy methyl-furfural.by variation ,the

reaction can yield equimolar amounts of levulic and formic acids.

12

3.PROCESS DESCRIPTION

13

PROCESS DESCRIPTION

At the sugar factory, the cane is piled as reserve supply in the cane yard so that

the factory, which runs, 24 hr/day will always have cane to grind. The delivery of the

cane to the factory depends upon the time of day, weather, and some other factors.

Very closely controlled operations never have more than a few hours worth of cane in

the cane yard, but more generally, the cane yard is fairly full toward evening and

nearly empty the next morning. The cane is moved from the cane yard or directly

from the transport to one of the cane table. Feed chains on the tables move the cane

across the tables to the main cane carrier, which runs at constant speed carrying the

cane into the factory.

The operator manipulates the speed of the various tables to keep the main

carrier evenly filled.In order to remove as much dirt and trash as possible, the cane

washed on the main carrier with as much water as is available. This includes

decirculated wash water and all of the condenser water. Of the order of 1 –2 % of the

sugar in the cane is washed out and lost in the washing, but it is considered

advantageous to wash. In areas where there are rocks in the cane, it is floated through

the so- called mud bath to help separate the rocks. The sugar recovered is normally

10-wt % of the cane, with some variation from region to region. Sugar cane has the

distinction of producing the heaviest yield of all crops, both in weight of biomass and

in weight of useful product per unit area of land.

Extraction of juice:

The juice is extracted from the cane either by milling, in which the cane is

pressed between the heavy rolls, or by diffusion, in which the sugar is leached out

with water. In either case, the cane is prepared by breaking into pieces measuring a

few centimeters. In the usual system, the magnets first remove the tramp iron, and the

cane then passes through two sets of rotating knives. The first set, called cane knives

turns at about 700 rpm, cuts the cane into pieces of 1 – 2 dm length, splits it up a bit,

and also act as a leveler to distribute the cane more evenly on the carrier. The second

set, called shredder knives turn faster and combine a cutting and a hammer action by

having a closer clearance with the housing. These quite thoroughly cutter and shred

the cane into a fluffy mat of pieces a few centimeters in the largest dimensions. In

14

preparing cane for diffusion, it is desirable to break every plant cell. Therefore the

cane for diffusion is put through an even finer shredder called a buster or fiberizer. No

juice is extracted in the shredders. In milling, the cane then goes to the crusher rolls,

which are similar to the mills, but have only two rolls, which have large teeth and are

widely spaced. These complete the breaking up of the cane to pieces of the order of 1

– 3 cm. The large amount of juice is removed here.

Milling:

The prepared cane passes through a series of mills called a tandem or milling

train. These mills are composed of massive horizontal cylinders or rolls in groups of

three, one on the top and two on the bottom in the triangle formation. The rolls are 50

–100 cm diameter and 1 –3 m long and have grooves that are 2 –5 cm wide and deep

around them. There may be anywhere from 3 – 7 of these 3 roll mills in tandem,

hence the name. These mills, together with their associated drive and gearing, are

among the most massive machinery used by industry. The bottom two rolls are fixed,

and the top is free to move up and down. The top roll is hydraulically loaded with a

force equivalent about 500 t. The rolls turn at 2 – 5 rpm, and the velocity of the cane

through them is 10- 25cm/s.

After passing through the mill, the fibrous residue, from the cane, called

bagassae, is carried to the next mill by bagassae carriers and is directed from the first

squeeze in a mill to the second by turn plate. In order to, achieve a good extraction, a

system of imbibition is used, bagassae going to the final mill is sprayed with water to

extract whatever sucrose remains; the resultant juice from the last mill is then sprayed

on the bagasse mat going to the next to last mill, and so on. The combination of all

these juices is collected from the first mill and is mixed with the juice from the

crusher. The result is called the mixed juice and is the material that goes forward to

make the sugar. The mills are powered with individual steam turbines. The exhaust

steam from the turbines is used to evaporate water from the cane juice. The capacity

of the sugarcane mills is 30 – 300 t of cane per hour.

15

Bagasse:

The bagasse from the last mill is about 50-wt% water and will burn

directly.Diffusion bagasse is dripping wet and must be dried in a mill or some sort of

bagasse press. Most bagasse is burned in the boilers that run the factories.

Clarification:

The juice from either milling or diffusion is about 12 – 18% solids, 10 – 15

pol (polarization) (percent sucrose), and 70 – 85% purity. These figures depend upon

geographical location, age of cane, variety, climate, cultivation, condition of juice

extraction system, and other factors. As dissolved material, it contains in addition to

sucrose some invert sugar, salts, silicates, amino acids, proteins, enzymes, and organic

acids; the pH is 5.5 – 6.5. It carries suspension cane fibre, field soil, silica,

bacteria,yeasts, molds, spores, insect parts, chlorophyll, starch, gums, waxes, and fats.

It looks brown and muddy with a trace of green from the chlorophyll. In the juice

from the mill, the sucrose is inverting (hydrolyzing to glucose and fructose) under the

influence of native invertase enzyme or an acid pH. The first step of processing is to

stop the inversion by raising the pH to 7.5 and heating to nearly 100oC to inactivate

the enzyme and stop microbiological action. At the same time, a large fraction of the

suspended material is removed by settling. The cheapest source of hydroxide is lime,

and this has the added advantage that calcium makes many insoluble

salts.Clarification by heat and lime, a process called defecation, was practiced in

Egypt many centuries ago and remains in many ways the most effective means of

purifying the juice. When the mud settles poorly, polyelectrolyte flocculants such as

polyacrylamides are sometimes used.The heat and high Ph serve to coagulate

proteins, which are largely removed in clarification. The equipment used for

clarification is of the Dorr clarifier type. It consists of a vertical cylindrical vessel

composed of a number of trays with conical bottoms stacked one over the other. The

limed raw juice enters the centre of each tray and flows toward the circumference. A

sweep arm in each tray turns quite slowly and sweeps the settled mud toward a central

mud outlet. The clear juice from the top circumference overflows into a header.

Diffusion juice contains less suspended solids than mill juice. In many diffusion

operations, some or all of the clarification is carried out in the diffuser by adding lime.

The mud from clarification is removed. The mud mostly consists of field soil and very

16

fined divided fibre. It also contains nearly all the protein (0.5 wt% of the juice solids)

and cane wax. The mud is returned to the fields. Although the clarification removes

most of the mud, the resulting juice is not necessarily clear. The equipment is often

run at beyond its capacity and control slips a little so that the clarity of the clarified

juice is not optimum. Suspended solids that slip past the clarifiers will be in the sugar.

Clarified juice is dark brown. The colour is darker than raw juice because the initial

heating causes significant darkening.

Evaporation:

Cane juice has sucrose concentration of normally 15%. The solubility of

sucrose in water is about 72%. The concentration of sucrose must reach the solubility

point before crystals can start growing. This involves the removal by evaporation of

93% of the water in the cane juice. Since water has the largest of all latent heats of

vaporization, this involves a very large amount of energy. In the energy crunch of the

late 1970s, the DOE found that the sugar industry was one of the largest users of

energy. The sugar industry already knew this very well and had been using multiple-

effect evaporators for saving energy for more than a century. The working of

multiple-effect evaporator can be seen in fig. In each succeeding effect, the vapours

from the previous effect are condensed to supply heat. This works only because each

succeeding effect is operating at a lower pressure and hence boils at lower

temperature.The result is that 1 kg of steam is used to evaporate 4 kg of water. The

steam used is exhaust steam from the turbines in the mill or turbines driving electrical

generators. The steam has therefore already been used once and here in the second use

it is made to give fourfold duty. The usual evaporator equipment is a vertical body

juice-in-tube unit. Several variations are in use, but the result is the same. The only

auxiliary equipment is the vacuum pump. Today, steam-jet-ejectors are general,

although mechanical pumps were formerly used. Since the cane juice contains

significant amounts of inorganic ions, including calcium and sulfate, the heating

surfaces are quick to scale and require frequent cleaning. In difficult cases, the heating

surfaces must be cleaned every few days. This requires shutting down the whole mill

or at least one heat-exchanger unit while the cleaning is done. Inhibited hydrochloric

acid or mechanical cleaners are usually employed.

17

Magnesium oxide is sometimes used instead of lime as a source of hydroxide.

Magnesium costs more, but it makes less boiler scale on the heaters. It is also easier to

remove because it is more soluble; however, for the same reason, more gets into the

sugar. Whether it is used or not depends upon the influence, standing, and

persuasiveness of the chief engineer who must keep the plant running and the chief

chemist who must make good sugar.The evaporation is carried on to a final brix of 65

– 68. The juice, after evaporation, is called syrup and is very dark brown, almost

black, and a little turbid.

Vacuum pans:

Vacuum pans have a small heating element in comparison to the very large

liquor and vapour space above it. The heating element was formerly steam coils but is

now usually a chest of vertical tubes called calandria. The sugar is inside the tubes.

There is a large center opening (downcomer) for circulation. The vacuum pan has a

very large discharge opening: typically 1 m dia. At the end of a strike, the massecuite

contains more crystals than syrup and is therefore very viscous.This large opening is

required to empty the pan in a reasonable time. At the top or down of the pan, there

are viscous entrainment separators. The pan may also be equipped with a

mechanicalstirrer. This is usually an impeller in or below the central downcomer,

driven by shaft coming down all the way from the top. The strike is started with liquor

just above the top of the calandria. The strike level cannot be very near the top

because of vapour space must be allowed for separation of entrainment. In operation,

the boiling is very vigorous with much splashing of liquid. The vacuum is maintained

mostly by condensing the vapours in a barometric condenser. In some cases, a surface

condenser is used. This serves as a source of distilled water and recovers heat. More

often, however, a jet condenser is used in which the cold condensing water is sprayed

into the hot vapour and both condensate and condenser water are mixed. A

supplementary vacuum pump is required to remove non condensable gases.

Centrifuging:

The massecuites from the vacuum pans enter a holding tank called a mixer

that has a very solely turning paddle to prevent the crystals from settling. The mixer is

18

a feed for the centrifuges. In a batch-type centrifuge, the mother liquor is separated

from the crystals in batches of about 1 t at a time.

Boiling systems:

In raw-sugar manufacture, the first strike of sugar is called the A strike, and

the mother liquor obtained from this strike from the centrifuges is called A molasses.

The pan yield in sugar boiling is about 50%. Because crystallization is an efficient

purification process, the product sugar is much purer than the cane juice and the

molasses much less pure. As an approximation, crystallization reduces the impurities

by factor of 10 or more in the product sugar. Therefore, almost all of the impurities

remain in the molasses. Enough molasses accumulates from boiling two first strikes to

boil a second strike. The B sugar from the second strike is only half as pure as that

from the first strike,but the B molasses is twice as impure. This can go on to a third

strike. At this point, 7/8 of the sugar from the cane juice is in the form of crystals and

1/8 in the C molasses. In practice, three strikes is about all that can be gotten from

cane juice. The trick is to maneuver to obtain good sugar, but at the same time have

the C or final molasses as impure as possible. The purity of the feed to the final strike

is adjusted to obtain the lowest possible purity of final molasses. Some of the C sugar

is redissolved and started over, some is used as footing for A and B strikes. The C

sugar is of very small crystal size so it is taken into the A or B pans as seed and grown

to an acceptable size. This practice is actually a step backward because it hides

impure C sugar in the center of better A and B sugars. The product raw sugar is a

mixture of A and B sugars. There are many variations in the boiling scheme, such as

two and four billings, blending molasses, and returning molasses to the same strike

from which it came. All of these tricks are used, depending on cane purity and

capabilities of the equipment available.

Coolers:

When the steam is turned off at the end of a sugar boiling, evaporation ceases

immediately and the mixture of crystals and supersaturated syrup in the pan starts

toward equilibrium, which is the point of saturation. In relatively pure sugar solutions,

this equilibrium is reached in few minutes well before the syrup crystallization is

slower and reaching equilibrium can take a significant amount of time. In the final

19

strike, the time an amount to days, so final strikes are not sent directly to the

centrifuges, but instead to crystallize, holding tank is in which the crystals grow as

much as possible and the super saturation in the molasses is reduced to 1.0. Since the

intention in handling the final molasses is to remove as much sugar as possible,

advantage is taken of the small temperature coefficient of solubility and the

massecuite is also cooled. The crystallizers are large tanks, some open-top, with a

slow-moving stirrer that is sometimes also a cooling coil. At the end of the holding

time, the massecuite is warmed slightly as it enters the centrifuge to lower the

viscosity and achieve better separation. The limiting factor in exhaustion of masses is

the viscosity. A little more water can always be boiled out, but the molasses must

remain fluid enough to run out of the pan, into the centrifuge and to flow between the

sugar crystals on the centrifuge screens.

Packing, storing and shipping:

Sugar is sometimes stored in bulk and then packaged as needed. Others

package the sugar and then warehouse the packages. The present trend is away from

consumer sized packages and toward bulk shipments.

20

4. MATERIAL BALANCE

21

MATERIAL BALANCE

BASIS – 100 TONS/DAY OF SUGAR CANE

MILLING

Cane – 100 tons Juice – 105 tons

Water – 70 tons solid – 15 tons

Solid – 16 tons water – 90 tons

MILLING

Fibre – 14 tons Bagasse – 30 tons

Solid – 1 ton

Water – 15 tons

Fibre – 14 tons

Cane + water = Juice + bagasse

100 35 105 30

Total inlet – 135 tons Total outlet – 135 tons

RAW JUICE HEATER

Juice – 105 tons Juice – 105 tons

Solid- 15 tons Solid- 15 tons

Raw Juice Heater

Water – 90 tons Water – 90 tons

Total inlet – 105 tons Total outlet- 105 tons

22

JUICE SULPHITOR



Juice Sulphitor

Water – 90 tons water- 90 tons

Lime – 0.05 ton lime – 0.05 ton

So2 – 0.02 ton so2 – 0.02 ton

Lime – (0.05 x(100/100))= 0.05 ton

So 2 - (0.02 x(100/100))= 0.02 tons

Total inlet – 105.07 tons Total outlet – 105.07 tons

JUICE HEATER

Juice – 105.07 tons juice – 105.07 tons



Juice Heater


So2 – 0.02 ton so2 – 0.02 ton


23

JUICE CLARIFIER

Juice – 105.07 tons Juice – 101.57 tons

Solid- 15 tons Solid- 14.195 tons

Water – 90 tons Water- 87.375 tons

Juice clarifier

Lime – 0.05 ton

So2 – 0.02 ton Cake – 3.5 tons

Solid – 0.815 ton

Water - 2.625 tons

Lime & So2 – 0.06 ton


EVAPORATOR 1

Vapour – 21.355 tons(82.50-63.09)

86 % water 65 % water


Solid- 14.195tons Solid- 14.195 tons

Evap

1

Water – 87.375 tons water-66.02 tons

Water –(0.65 x101.57= 66.02 tons)

Total inlet – 101.57 tons Total outlet – 80.21(101.57- 21.355)

24

EVAPORATOR 2

Vapour – 10.1tons(87.375-55.86)

65%water 55 % water



Evap

2

Water – 66.02 tons water-55.86tons

Water – (0.55 x101.57= 55.86 tons)

Total inlet – 80.21tons Total outlet – 67.94tons(80.21- 10.16)

EVAPORATOR 3

Vapour – 10.16tons(55.86-45.70)




Evap 3

Water – 55.86 tons Water-45.70 tons

Water –(0.45 x101.57= 45.70 tons)

Total inlet – 67.94 tons Total outlet – 59.89 tons(67.94-10.16)

25

EVAPORATOR 4

Vapour – 5.08 tons(45.70-40.62)




Water – 45.70 tons Water – 40.62tons

Evap 4

Water – (0.40 x101.57= 40.63tons)


VACUUM PAN A

Vapour – 30.47tons(45.70-40.62)



Water – 40.62 tons water – 10.15tons

Vac pan A

Water –(0.15 x101.57= 10.15tons)


26

VACUUM PAN B

Vapour – 8.07 tons(14.533-6.7914)

2% water



Vac pan B

Water –(0.02 x101.57= 2.06tons)

Total inlet – 15.01tons Total outlet – 6.945 tons(15.01-8.07)

VACUUM PAN C

Vapour – 1.28 tons(2- 0.72)

Solid- 3.642ons Solid- 3.642 tons


Vac pan C


27

CENTRIFUGAL A

Solid – 14.195 tons Molasses – 15.02 tons Centrifugal A

Water – 10.15 tons Water – 10.10 tons

Solid – 4.915 tons

Crystal sugar – 9.25 tons

Sugar loss – 0.03 ton

Outlet – 9.3tons(9.25+0.05)

Outlet – 15.025tons(10.10+4.915)

Inlet – 24.34tons(10.15 + 14.195 ) Total –24.34tons(15.02+9.3+0.03)

CENTRIFUGAL B

Solid – 4.195 tons Molasses – 10.662 tons


Centrifugal B

Solid – 3.642 tons

Crystal sugar – 1.253 tons

Sugar loss – 0.02 ton

Outlet – 3.15tons(3.1+0.05)

Outlet – 10.662tons(6.7414+3.921)

Inlet – 6.945tons(4.915+2.030 ) Total – 6.945(1.283+5.642+0.02)

28

CENTRIFUGAL C

Solid – 3.642tons Molasses – 3.5 tons


Solid – 2.8 tons

Centrifugal C

Crystal sugar – 0.832tons

` Sugar loss – 0.01 ton

Inlet – 4.362tons(0.72 + 3.642 ) Total – 4.362tons(0.852+3.5+0.01 )

CONVEYOR

Sugar 1 – 9.3 tons

Sugar 2 - 1.283 tons SUGAR – 11.435tons Conveyor

Sugar 3 - 0.852 tons

(9.3 + 1.283 + 0.852 )= 11.435

DRYER

Moisture – 0.04 ton

Sugar – 11.435 SUGAR – 11.395 tons

Moisture – 0.1 tons Moisture – 0.06 tons Dryer

Hot air – 0 %moisture content

29

5. ENERGY BALANCE

30

ENERGY BALANCE

RAW JUICE HEATER



Raw Juice Heater

Water – 90 tons Water – 90 tons

Total inlet – 105 tons Total outlet- 105 tons

Cp of sucrose (solid) 0.299 kcal/kg

Enthalpy of solid in 15 x 0.299(32-25) x103 = 31395kcal

Enthalpy of water in 90 x 0.999(32-25) x 103 = 629370kcal

Enthalpy of solid out 15 x 0.299(71-25) x 103 = 206310kcal

Enthalpy of water out 90 x 0.999(71-25) x 103 = 4156560kcal

Enthalpy of vapor out 0

Total enthalpy in 660765(31395+629370)kcal

Total enthalpy out 4362870(206310+4156560)kcal

Mass total steam required 8071.9149(3702105/540.5)kcal

Total heat required 3702105(total E out-total E in)kcal

31

JUICE SULPHITOR




JUICE SULPHITOR


So2 – 0.02 ton so2 – 0.02 ton

Enthalpy of solid in 15 x 0.299(71-25) x 103 = 206310kcal


Cp of Ca(oH)2 21.4cal/mol – 21.4/74 = 0.289kcal/kg

Enthalpy of Ca(oH)2 in 0.05 x0.289(71-25) x 103 = 664.7kcal

Cp of So2 7.7+0.0053T-0.00000083T-2

=8.072 cal/mol

= 8.072/64 kcal/kg

=0.126 kcal/kg

Enthalpy of So2 in 0.02 x 0.126(71-25) x 103 = 115.92kcal/kg

Enthalpy of solid out 15.07 x0.299(70-25) x 103 = 202766.85kcal


Total enthalpy in 4363650.62 kcal

Total enthalpy out 4268966.85kcal

Total heat required 94683.77kcal(total E out-total E in)

32

JUICE HEATER




Juice Heater


So2 – 0.02 ton so2 – 0.02 ton

Enthalpy of solid in 15.07 x0.299(70-25) x103 = 202766.85kcal

Enthalpy of water in 90 x1.004(70-25) x103 = 4066200kcal

Enthalpy of solid out 15.07 x 0.299(103-25) x103 = 351462.54kcal


Enthalpy of vapor out 0

Total enthalpy in 4268966.85kcal

Total enthalpy out 7455702.54kcal

Mass total steam required 5895.9032kg

Total heat required 3186735.69kcaltotal E out-total E in)

33

JUICE CLARIFIER


Solid- 15 tons Solid- 14.195 tons

JUICE CLARIFIER

Water – 90 tons Water- 87.375 tons

Lime – 0.05 ton

So2 – 0.02 ton Cake – 3.5 tons

Solid – 0.815 ton

Water - 2.625 tons

Lime & so2 – 0.06 ton

Enthalpy of solid in 15.07 x 0.299(103-25) x 103 = 349830kcal


Enthalpy of solid out 14.195 x 0.299(102-25) x 103 = 326696.37kcal

Enthalpy of water out 87.375 x1.012(102-25) x 103 = 6808609.5kcal

Enthalpy of mud juice out 3.44 x0.126 x(102-25) x 103 = 33.3748 x103 kcal

Enthalpy of Lime out 0.045x 0.289(102-25)x103 = 1.0013 x103 kcal

Enthalpy of so2 out 1.3987 x 102 kcal

Total Enthalpy in 7397.91 x103 kcal

Total Enthalpy out 7171.0803 x103 kcal

Total heat released 226.8297 x103 kcal

34

EVAPORATOR 1

Vapour – 21.355 tons(82.50-63.09)




Water – 87.375 tons Water-66.02 tons

Evap

1

Clear juice in –

Hf = mCp∆t

∆T = 102-102 = 0

Cp = 0.96 kcal/kg

M = 101.57 ton

Hf = 0

Similarly Hp = 0

Enthalpy of steam in S λ s

Latent heat at 126 C 540. 5 kcal/kg

Enthalpy of vapor out m λ

Enthalpy at 102 536.45 kcal/kg = 21.355 x 536.45

= 11455.88 x 103 kcal

Balance equation

Hf + Sλ = Hp + m λ

0 + S x540.5 = 0 + 11455.88

S = 21.9498 x 103 kg

35

EVAPORATOR 2

Vapour – 10.16 tons(87.375-55.86)




Evap 2

Water – 66.02 tons Water-55.86tons

Hf = mcp∆t

Cp = 0.96 kcal /kg

∆T = 107-78 = 24

Hf = 80.21 x 0.96 x24 = 1848.03 x 10 3 kcal

Enthalpy of vapor in V1 λv

Λv = 536.45 V1 x 536.45

Hp = mcp∆t ---∆t=0

Enthalpy of vapor out m λv

10.16 x531.11 = 5396.07 x 103 kcal

Balance equation :-

Hf + m λ = Hp + vapor out enthalpy

1848.03 x 10 + V1 x 536.45 = 0 + 5396.07 x 103

V1 = 6.613 x 103 kg

36

EVAPORATOR 3

Vapour – 10.16tons(55.86-45.70)




Water – 55.86 tons water-45.70 tons

Evap

3

Hf = mcp∆t

Cp = 0.96 kcal /kg

∆T = 66-55 = 11

Hf = 59.89x 0.96 x11 = 632.43 x 10 3 kcal


Λv = 531.11

V1 x 531.11

Hp = mcp∆t ---∆t=0


= 10.16 x529.18 = 5376.46x 103 kcal

Balance equation :-


806.976 x 103 + V1 x 531.11 = 0 + 5376.46 x 103

V1 = 8.603 x 103 kg

37

EVAPORATOR 4

Vapour – 5.08 tons(45.70-40.62)




Water – 45.70 tons Water – 40.62tons

Evap

4

Hf = mcp∆t

Cp = 0.96 kcal /kg

T = 78-66 = 12

Hf = 70.05 x 0.96 x12 = 806.97 x 10 3 kcal


Λv = 534.211

=V1 x 534.211

Hp = mcpt ---t=0


= 5.08 x529.18 = 2683.51x 103 kcal

Balance equation :-


632.43 x 103 + V1 x 534.211 = 0 + 2683.51 x 103

V1 = 3.8394 x 103 kg

38

VACUUM PAN A

Vapour – 30.47tons(45.70-40.62)




Vac pan A

Enthalpy of juice in = mcpΔt

= 54.81 x0.96 x(55-25)

= 1578.528 x 10 kcal

Vapor in = Sλ = S(540.5)

Enthalpy of juice out = enthalpy of crystallization + sensible heat

= (9.3 x 526) + (14.995 x0.96x(60-25)

= 5395.632 x 10 3 kcal

Vapor out = 30.46 x 540.5

= 16463.63 x 10 3 kcal

Heat balance

1578.528 x 103 + 540.5 S = 5395.632 x 103 + 16463.63

S = 37.5221 x 10 3 kg

39

VACUUM PAN B

Vapour – 8.07 tons(14.533-6.7914)

2% water



Vac pan B


= 15.015 x0.96 x(60-25)

= 1578.528 x 10 kcal



= (1.283 x 526) + (5.632 x0.96x(65-25))

= 891.1268 x 10 3 kcal

Vapor out = 30.46 x 540.5

= 4071.315 x 10 3 kcal

Heat balance

504.504 x 103 +540.5 S = 891.1268 x 103 +4071.315

S = 8.8363 x 10 3 kg

40

VACUUM PAN C

Vapour – 1.28 tons(2- 0.72)

Solid- 3.642ons Solid- 3.642 tons

Water – 2.000 tons water – 0.72ton

Vac pan C


= 5.642 x0.96 x(70-25)

= 243.734 x 10 kcal



= (0.832x 526) + (3.51 x0.96x(70-25)

= 589.264 x 10 3 kcal

Vapor out = 1.28 x 540.5

= 645.76 x 10 3 kcal

Heat balance

243.734 x 103 + 540.5 S = 589.264 x 103 + 645.76

S = 37.5221 x 10 3 kg

41

6. EQUIPMENT DESIGN

42

EVAPORATOR DESIGN

Feed to the first effect F = 101.57 tons/day

= 1.1756 kg/s

Liquid out from last effect = 54.81 tons/day

= 0.6261 kg/s

Evaporator load = 1.1756 – 0.6261

= 0.5495 kg/s

EFFECT Liquid out (Kg/s) Vapour out (Kg/s)

1 L1 = 0.9283 V1 = 0.2471

2 L2 = 0.7863 V2 = 0.1175

3 L3 = 0.6932 V3 = 0.1175

4 L4 = 0.6343 V4 = 0.0588

To calculate ∆T :-

Steam at 1st effect

Ps = 1.634 bar

T1s = 126 C

Pr in fourth effect = 660mmHg->0.1356 bar

T5s = 55 C

Therefore ∆T = T1s – T5s->126 – 55 = 71 C

Calculate ∆t in each effect :-

q1 = q2 =q3 =q4

u1A1∆T1 = u2A2∆T2= u3A3∆T3= u4A4∆T4

Usually the areas in all the effects are equal

Therefore

u1∆T1 = u2∆lT2= u3∆T3= u4∆T4

43

According to Hugot the overall heat transfer coefficent in each effects are given as

Effect 1 2 3 4

U(Btu/hr ft F) 400-500 275-375 200-275 125-150

Assuming overall heat transfer coefficient in each effect as follows

Effect 1 2 3 4

U(Btu/hr ft F) 450 325 250 140

U(W/m2 K) 2555 1845 1420 795

∆T2 /∆ T1 = U1/U2

∆T2 / ∆T1 = (2555/1845) = 1.385

∆T2 = 1.385 ∆T1

∆T3 / ∆T2 = U2/U3

∆T3 / ∆T2 =(1845/1420) = 1.299

∆T3 = 1.299 ∆T2

∆T4 / ∆T3 = U3/U4

∆T4 / ∆T3 =(1420/795) = 1.7862

∆T4 = 1.7862 Del T3

t1 + t2 +t3 +t4 = 71 C

t1 (1+1.385+1.299x1.385+1.299x1.385x1.7862) = 71

t1 = 71/7.58 = 9.37 C

t2 = 1.385 x t1 = 12.98 C

t2 = 1.299 x t2 = 16.87 C

t4 = 1.786 x t3 = 30.13 C

Steam S = 21.9498 tons/day = 0.2540 kg/s

To calculate area in each effect :-

44

Enthalpy 1s = 2218.2 KJ/kg




q1 = S x Enthalpy 1s

=0.2540 x2218.2

=563.4228 Kw

q2 = V1 x Enthalpy 2s

=0.2471 x 2246.02

=554.9915 Kw


=0.1175 x 2272.21

=266.9846 Kw


=0.1175 x 2315.66

=272.09 Kw

A1 = (q1/u1t1)

= 563.4228 x (103 /2555 x 282.37)

= 0.7809 m2

A2 = (q2/U2t2)

= 554.9915 x (103 /1845 x 285.98)

= 1.0518 m2

A3 = (q3/u3t3) t3--16.87 C = 289.87 K

= 266.9846 x (103 /1420 x 289.87)

= 0.6486 m2

A4 = ( q4/u4t4)

45

= 272.09 x (103 /795 x 303.13)

= 1.1290 m2

Detailed design :- Evaporators are designed

On the basis of the highest heating area

Hence area of each effect = 1.1290 m2

Let us select 50 mm O.D(40mm I.D) tubes each of 2m arranged on 65mm sq.pitch.

N =No of tubes in the chest

3.14 xDo x L x N = 1.1290

3.14(0.05) 2 N = 1.1290

N= 3.6 = 4

Down take area(Ad)

Ad = (3.14/4) D2i N x 0.17

= (3.14/4)(0.04)2 x 4 x 0.75

= 0.004 m2

Diameter of downtake

= sq root of( Ad x 4/3.14)

= sq root of (0.004 x 4/3.14)

=0.071 m

Annular area = Np2t

=4 x (0.065)2

= 0.02 m2

Height of evaporator = 3 x tube length

= 3 x 2 = 6m

Surface area of each tube a = 3.14 x d0 x L

= 3.14 x 0.05 x 2

=0.314 m2

46

Area occupied by tubes = N x (1/2) x P2t x sin α

α = 60

=4 x (1/2) x 90.065)2 x 0.866

=0.0073 m2

But actual area is more than this.

Hence this area is to be divided by factor which varies from 0.8 to 1.0.

Let this factor be 0.9

Therfore actual area required = (0.0073/0.9) 0.0081m2

Total area of tube sheet in evaporator = downtake area +area occupied by tubes

= 0.004 + 0.0081

= 0.0121 m2

Thus tube sheet diameter = sq root of (4 x area of tube sheet) /3.14

Evaporator diameter = 0.1241m

Design specification :-

Evaprator height = 6m

Evaporatr diameter = 0.1241m

47

CENTRIFUGAL DESIGN

Gravity factor = centrifugal force/gravitational force

G = mw2r/mg

M – is the mass

W – is the angular velocity

r- is the radius of the basket of the centrifugal machine

g- is the gravitational force = 9.81 m/s2

Angular velocity (w) = (2x3.14 x r.p.m of the machine)/60

Centrifugal force mw2r = (m x (2 x 3.14 x r.p.m) 2x r)/602

Therefore Gravity factor (G) = (m x (2x3.14 x r.p.m)2x r)/(m x 9.81 x 602)

G = (r.p.m) 2 x r / 900

=(r.p.m)2 x d /1800

D= diameter of the basket centrifugal machine.

D iameter will be in the range of (1.05-12.22m)

Assume D= 1.22m, r.p.m = 1500

G= (1500)2 x 1.22/1800 = 1525

Capacity

1.The capacity to handle the quantity of syrup per hour or per cycle

2. capacity of sugar produced/hr or per cycle

The capacity depends on the following screen

a. Surface area of the basket screen

b. Thickness of the massecuite layer over the screen

48

The layer of massecuite is generally 14 to 15% of the diameter of the basket.but

considered for safe working as 10 to 14 %

Hence it is suggested to take the

1. Maximum layer thickness as 0.14D

2. Minimum layer thickness as 0.12D

D = diameter of the basket

Capacity then can be calculated by the formula on volume basis

V = 3.14 x e x H x (D-e) for flat bottom machines

Where

V = volume of massecuite in (dm3) or litres

E = Thickness of massecite in dm3

H = Interior height of the basket in dm

D = Inside diameter of the basket in dm

So e =(0.14 x 1.22)=0.1708m

Assume H = 0.76m ( range from 0.61-0.76m)

V = 3.14 x 0.1708 x 0.76 x (1.22-0.1708)

V = 0.4278 m3 = 428 dm3

Formula may be verified the values given by Hugot very closely to the following

formula

1. Theoretical V = 390 x (1.22)2 x 0.76

= 428m3

2. Practical V = 340 x (1.22)2 x 0.76

= 441 m3

D = diameter of meters

H = Height in meters

49

As per hugot it is assumed that sugar obtained/m3 of massecuite is 800 kg on this

basis and the value given as per Hugot the capacity can be calculated in the formula as

Weight of sugar(kg)/m3 volume of massecuite = 800 x m3 of massecuite as given by

Hugot

So Weight of sugar = 800 x 0.4278

=342.29 kg

Capacity of machine at different size/cycle are in weight of sugar/cycle.

Power requirement

Power required (hp) = D4 x H x (r.p.m)2 x (1+4 x r.p.m) x (105/75)

=(1.22)4 x 0.76 x (1500)2 x (1+4 x 1500)(105/75)

hp = 37.1

1hp = 0.74kw

So power required = 27.8kw

50

7. PROCESS CONTROL

51

PROCESS CONTROL

The even operation of a process is dependent upon the control of the process

variables. when the flowsheet is laid out for the processs, the temperature, pressure

and fluid flow quantites are theoretically fixed in accordance with the heat, pressure

and material balance.The translation of flowsheet into an operable plan requires that

special provision be made to assure the relative constancy of the various quantites and

qualities. Automatic control is employed to measure suppress and correct and modify

changes of four principal types of process variation.

1. Temperature control

2. Pressure control

3. Flow control

4. Level control

It is the objective of all controllers to regulate process variables, and to do so

they must be capable of first measuring the variables. Some instruments are equipped

to indicate the variable in a continuously readable from and others recorders are

equipped with pen and ink on a traveling chart calibrated for time. In modern process

industries,digital control systems(DCS) is used for effective control of process

variables.

Flow metering

The measurement of flow rate is done for the purpose of determining the

properties of the materials introduced, the amount of material evolve by the process.

Secondly flow measurement are made for the purpose of cost accounting usually for

steam and water services. Instruments like ventriument, orificement, rotameter are

used to measure the flow rate.

52

VARIABLE MODE OF CONTROL

Temperature P,PI,PID

Pressure P,PI,PID

Flow P,PI,PID

Control station

Well engineered display is important in individual indicating and recording

instruments becomes crucial in control room design when data on large and often

critical process operations must be used by a human operator. Indicator and recorders

must be coordinated with controls, switches, alarms and auxillary equipments so as to

present a clear easily grasped display of the process condition. There are four essential

parts of every control station. They are

1. Process variable indicator

2. A set point mechanism

3. An adjustment device called manual ,that directly manipulates signal to contol

valves.

4. An output signal indicator.

53

8. POLLUTION CONTROL AND SAFETY

54

POLLUTION CONTROL AND SAFETY

Sugar industry is basically seasonal in nature and operates only for 120 to

200days in a year (early November to April). A significantly large volume of waste is

generated during the manufacture of sugar and contains a high amount of pollutional

load particularly in terms of suspended solids, organic matter, and press mud, bagasse

and air pollutants. Therefore an attempt has been made to present an overview of

waste management in sugar industry in India.

WASTE GENERATION:

(A) WASTEWATER

Mill house: Mill house wastewater is derived from continuous gland cooling

and intermittent floor washing and contains high amounts of oils and grease and sugar

from pills and leaks. Boiler Blow-down: Boiler blow-down is fairly clean water

except that it contains high dissolved solids and phosphates.

Rotary filter: Filter cloth is periodically washed and constituents a source of

waste water.

Condensates: The vapours from the last effect evaporator and pan boiling are

Separately cooled in barometric condensers and the condensate goes to the pond. A

part of the cooled water from the pond is recycled into the sugar mill, but a large

portion is discharged as wastewater. If the mill operates without overloading, the

evaporator and vacuum pan condensate is quite clean and the entire quantity can be

reused. But many a times, overloading and poor operating conditions can lead to

significant sugar losses in the condensates through entrainment and thus polluting the

water.

Occasional Spills and Leaks: Leaks from pumps and pipes in the evaporators

and centrifuge house, along with periodical floor washings, constitute another source

of waste water. Although the flow is intermittent and volume discharged is not large,

it represents the most polluting fraction of sugar mill wastewater.

55

Condensate Washings: Evaporators, juice heaters, pans, etc are cleaned once

in 20 Days for removal of deposited scales. Caustic soda, sodium bicarbonate and

hydrochloric acid are used for scale removal. Normally the caustic soda washings are

stored and reused for cleaning operations. However, in India, most of the sugar mills

discharge these chemicals into the drains. After the equipment is boiled with caustic

soda and rinsed with fresh water, it is cleaned with dilute hydrochloric acid using an

inhibitor. The wastewater is discharged into the drains, as the recovery of the

chemicals may not prove to be economical. It is seen that the wastewater has small

organic load but inorganic content may be high to pose a shock-load to wastewater

treatment facility (occasional discharge, once in fortnight). It is suggested to have a

holding tank and mix this wastewater gradually to the final effluent to avoid shock

loading on the treatment plant.

Sulphur and Lime Houses: The washings of sulphur and lime house would

contain a considerable amount of inorganic solids, which include carbonates and

sulphates. The effluents from these two units when combined would give neutral pH

value of waste.This wastewater does not contribute to organic pollution but can be

characterized as inorganic wastewater.

WASTEWATER PARAMETERS

BOD: - This is the measure of the oxygen consuming capabilities of organic

matter.During decomposition, organic effluents exert a BOD that can deplete oxygen

supply BOD is generally measured and expressed in parts per million or milligrams

per litre.The effluents from a raw sugar factory can vary between hundred to several

thousands mg/l.

Dissolved Oxygen: - This is water quality constituent. It is measured and

expressed as parts per million or mg/l.

Total Suspended Solids (TSS): - Suspended solids when they settle form

sludge on the stream, lakebed and they are most damaging to the life in water.The

different modes of disposal of wastes are:

56

1. Disposal into water bodies

2. Evaporation in open pits

3. Disposal into ocean

4. Press mud for fertilizer

5. Bagasse for paper and pulp and fibre

(B) SOLID WASTES

Bagasse: It is estimated that bagasse contributes to 33.3% residue of the total

cane crushed. It has a calorific value of about 1920 kcal/kg and is mainly used as fuel

in boilers for steam generation.

Press Mud: It contains all non-sucrose impurities along with CaCO3

precipitate and sulphate. Press mud from double sulphitation process contains

valuable nutrients like nitrogen, phosphorous, potassium, etc, and therefore used as

fertilizer. The press mud from double carbonation process is used for land filling and

is not used as manure .

(C) AIR POLLUTANTS

The bagasse, on burning, produces particulates, viz., unburnt fibres, carbon

particles and gaseous pollutants like oxides of nitrogen, water vapour and other

organic compounds. Of the particulate waste, the heavier particles slowly settle down

in the surrounding area. Such dust fall leads to the problems of cleaning, reduction in

property value, effect on vegetation, etc. The main gaseous pollutants are CO, which

is altogether not measured by any unit, and CO2 is reported to be in the range of 12 –

14%.

57

WASTEWATER REDUCTION AND BY-PRODUCT RECOVERY:

The following areas are important to economize the usage of water.

(A) COOLING WATER

1. Mainly used for condenser, bearing cooling, sulphur/lime houses and crystallizer

for formation of crystal

2. In condenser, water gets mixed with vapour. However, adjusting pH along with

make-up water to keep dissolved solids in check can recycle it.

3. Evaporator cooling water contains entrained sugar and acid because of excess of

SO2 and can be recycled. Improvement in the designs of evaporator/pan boiler

can Reduce the loss. Losses will also be due to evaporation, splashing and

percolations.

4. Keeping the temperature of incoming water between 30o and 35oC can reduce

losses due to evaporation. Splashing and percolation can be checked by proper

maintenance.

5. Cooling water for bearings, power generation, etc., can be reused safely.

(B) PROCESS WATER

Sugar mill employs both hot and cold water for its various processes such

asFilter cake washing, lime preparation, dilution for lowering brix, Dilution in

evaporators and pans, Massecuite, Magma making and Crystal washing in

centrifugals.

1. Water requirement before evaporator storage is about 1/5 to ¼ of steam used

whilethat used after evaporator requires approximately equal amounts, as for

steam.Careful attention is required after evaporator stage to control water usage.

2. Hot water can be used in place of cold water to reduce the quantity of steam

required.

3. It is preferable to use 18 – 20% maceration by equally adjusting it from the top

andthe bottom of bagasse bed feeding to the last mill at a pressure of 7 – 14

58

kg/cm2 rather than merely pouring the same at 25 to 30% of cane (about 5 – 7%

water can be saved).

4. If maceration is high enough, there will not be any need of dilution water for

juice.

5. To reduce water quantity, light molasses can be used for magma making.

Washing Water: Wash water may contain sugar and therefore requires

treatment and should not be recycled. Periodic cleaning results in high BOD and it

also contain caustic soda and weak acids. Returning it to the service water tank can

reuse water.

Testing Water: This water is safe for returning it to the service water tank.Oil

and Grease providing suitable oil and grease traps can eliminate this.

Chemical Reuse: The stored and settled supernatant can be reused with a little

addition of fresh caustic soda for next cleaning operation.

Molasses Handling: It is necessary to store molasses in RCC tanks or steel

tanks above ground level. Otherwise, there is a possibility of ground water

contamination.

The high BOD of molasses may cause pollution problems due to mishandling.

(C) PRODUCT RECOVERY

The by-products available from sugar mills are bagasse, furnace ash,

molassesand filter mud. The uses of these by products are given below. If all the by

products are used for transformation into value added products, (resource recovery), it

will minimize the pollution to large extent.

Bagasse: These are used for steam, power, charcoal, briquettes and methane &

producer gas.

Molasses: These are used for fertilizer and cattle feed.

Filter mud: For fertilizer.

Boiler ash: For foundry material.

59

SAFETY:

Sugar in boiler feed water causes water to foam, which will lead accidents. If

notpresent in large quantity. It is decomposed by heat into products that are

detrimental to the tubes and shells of boilers causing pitting and overheating.If sugar

is present in small amounts their traces will be eventually accumulated on the boiler

tubes as a harmful and dangerous carbonaceous deposit. the break down of sugar also

forms harmful organic acids. To prevent this lime is added to feed water to maintain

pH = 8.0. A pronounced odour develops in the steam if boiler water contains sugar.

Under such conditions the contaminated feed water is turned to sewer and the boilers

are blown off. To prevent these hazards tests are conducted to determine amount of

sugar traces in water. The most commonly used tests are Naphthol test and

Aresenomolybdate test.

60

9. COST ESTIMATION AND ECONOMICS

61

COST ESTIMATION AND ECONOMICS

Given in the literature is the cost versus size Nomograph, from which the cost

of cane sugar plant within the crushing capacity between 100 – 500 TPD can be

calculated.

The cost for 5000 TPD crushing capacity plant with Chemical Engineering

Plant Cost Index (CE) =130 (Basis = 1957 -59; CE = 100) is as follows:

Cost for 100 TPD crushing capacity = Rs. 2.05 x 106

To find present cost:

A cost index is merely an index value for a given point in time showing the

cost at that time relative to a certain base time. If the cost at some time in past is

known, the equivalent cost at the present time can be determined by multiplying the

original cost by the ratio of the present index value to the index value applicable when

the original cost was obtained.

Obtained from the Internet that Chemical Engineering Plant Cost Index is

given as:

Cost index in 2002 = 402

Original cost value is obtained when cost index was 130.

Thus,

Present cost of Plant = (original cost) x {(present cost index)/(past cost index)}

= (2.05 x 106) (402/130) = Rs. 6.34 x106

Fixed Capital Investment (FCI) = Rs. 6.34 x106

Generally fixed capital investment cost is 85% of total capital investment.

Therefore Total Capital Investment = (FCI)/0.85 = Rs 7.457 x 106

62

Estimation of Total Capital Investment Cost:

(I) Direct Costs:

(A) Material and labour involved in actual installation of complete facility (70-85% of

fixed-capital investment)

a) Equipment + installation + instrumentation + piping + electrical + insulation +

painting

(50-60% of Fixed-capital investment)

a. Purchased equipment cost (PEC):

RANGE = 15-40% of Fixed-capital investment

Let Purchased Equipment Cost = 30% of Fixed-capital investment

PEC = 30% of Rs. 6.34 x106

= Rs. 1.902 x106

b. Installation, including insulation and painting:

RANGE = 25-55% of purchased equipment cost.

Let Installation Cost = 35% of Purchased equipment cost

= 35% of Rs. 1.902 x106

= Rs. 0.6657 x106

c. Instrumentation and controls, installed:

RANGE = 6-30% of Purchased equipment cost.

Let Instrumentation Cost = 10% of Purchased equipment cost

= 10% of Rs. 1.902 x106

= Rs. 0.1902 x106

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d. Piping Installed:

RANGE = 10-80% of Purchased equipment cost

Let Piping Cost = 40% of Purchased equipment cost

= 40% of Rs. 1.902 x106

= Rs. 0.7608 x106

e. Electrical, installed:


Let Electrical cost = 25% of Purchased equipment cost

= 25% of Rs. 1.902 x106

= Rs. 0.4755 x106

Therefore Total cost for (A) = Rs. 4 x106

(B) Buildings, process and Auxiliary:


Let Buildings, process and auxiliary cost = 30% of PEC

= 30% of Rs. 1.902 x106

= Rs. 0.5706 x106

(C) Service facilities and yard improvements:


Let Facilities and yard improvement cost = 50% of PEC

= 50% of Rs. 1.902 x106

= Rs. 0.951 x106

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(D) Land:


Let the cost of land = 6% of PEC

= 6% of Rs. 1.902 x106

= Rs. 0.1141 x106

Therefore Total Direct Cost = 5.635 x106

(II) Indirect costs:

Expenses, which are not directly involved with material and labour of actual

installation of complete facility (15-30% of Fixed-capital investment)

(A) Engineering and Supervision:

RANGE = 5-30% of Direct costs

Let the cost of engineering and supervision = 10% of Direct costs

= 10% of Rs. 5.535 x106

= Rs. 0.5635 x106

(B) Construction Expense and Contractor’s fee:

RANGE = 6-30% of Direct costs

Let construction expense & contractor’s fee = 15% of Direct costs

= 15% of Rs. 5.635 x106

= Rs. 0. 8452 x106

(C) Contingency:

RANGE = 5-15% of Fixed-capital investment

Let the contingency cost = 8% of Fixed-capital investment

= 8% of 6.34 x106

= Rs. 0.5072 x106

Thus, Total Indirect Costs = Rs. 1.916 x106

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(III) Fixed Capital Investment:

Fixed capital investment = Direct costs + Indirect costs

= Rs 7.5509 x106

(IV) Working Capital:

RANGE = (10-20% of Total-capital investment)

Let the Working Capital = 15% of Total-capital investment

= 15% of 7.457 x106

= 0.15 X 7.457106

= Rs. 1.1181 x106

(V) Total Capital Investment (TCI):

Total capital investment = Fixed capital investment + Working capital

= 8.6694 x106

Estimation of Total Product cost:

(I) Manufacturing Cost = Direct production cost + Fixed charges + Plant overhead

cost.

(A) Fixed Charges: (10-20% total product cost)

i. Depreciation: (depends on life period, salvage value and method of calculation-

about 10% of FCI for machinery and equipment and 2-3% for Building Value for

Buildings)

Consider depreciation = 10% of FCI for machinery and equipment and 2.5% for

Building Value for Buildings)

i.e. Depreciation = (0.10 x 7.5509 x 107) + (0.025 x0.025 x 107)

= Rs. 0.7693 x 106

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ii. Local Taxes: (1-4% of fixed capital investment)

Consider the local taxes = 2% of fixed capital investment

i.e. Local Taxes = 0.02 x 7.5509 x 106 = Rs. 0.1510 x 106

iii. Insurances: (0.4-1% of fixed capital investment)

Consider the Insurance = 0.6% of fixed capital investment

i.e. Insurance = Rs. 0.0453 x 106

iv. Rent: (8-12% of value of rented land and buildings)

Consider rent = 10% of value of rented land and buildings

= Rs. 0.0.05706 x106

Thus, Total Fixed Charges = Rs. 1.0227 x106

(B) Direct Production Cost: (about 60% of total product cost)

Now we have Fixed charges = 10-20% of total product charges – (given)

Consider the Fixed charges = 15% of total product cost

Total product cost = Total fixed charges/0.15

Total product cost = 1.02271 x 106/0.15

Total product cost (TPC) = Rs. 6.8181 x106

i. Raw Materials: (10-50% of total product cost)

Consider the cost of raw materials = 25% of total product cost

Raw material cost = 25% of 6.8181 x106 = Rs. 1.7045 x106

ii. Operating Labour (OL): (10-20% of total product cost)

Consider the cost of operating labour = 12% of total product cost

Operating labour cost = 12% of 6.8181 x106 = 0.12 x6.8181x106

= Rs. 0.8181 x106

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iii. Direct Supervisory and Clerical Labour (DS & CL): (10-25% of OL)

Consider the cost for Direct supervisory and clerical labour = 12% of OL

Direct supervisory and clerical labour cost = 12% of 08181 x 106

= 0.12 x 0.8181 x 106

Direct supervisory and clerical labour cost = Rs. 0.096 x106

iv. Utilities: (10-20% of total product cost)

Consider the cost of Utilities = 12% of total product cost

Utilities cost = = Rs. 0.8181 x106

v. Maintenance and repairs (M & R): (2-10% of fixed capital investment)

Consider the maintenance and repair cost = 5% of fixed capital investment

i.e. Maintenance and repair cost = 0.05 x7.5509x 106 = Rs. 0.37754 x106

vi. Operating Supplies: (10-20% of M & R or 0.5-1% of FCI)

Consider the cost of Operating supplies = 15% of M & R

Operating supplies cost = 15% of Rs. 0.37754 x106 = 0.15 x Rs. 0.37754 x106

= Rs. 0.05663 x106

vii. Laboratory Charges: (10-20% of OL)

Consider the Laboratory charges = 14% of OL

Laboratory charges = 14% of 0.8181 x 106= 0.1145 x106

viii. Patent and Royalties: (0-6% of total product cost)

Consider the cost of Patent and royalties = 2% of total product cost

Patent and Royalties = 2% of 6.8181 x 106 = 0.1363 x 106

Thus, Direct Production Cost = Rs. 4.1236 x106

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(C) Plant overhead Costs: (50-70% of Operating labour, supervision, and

maintenance or 5-15% of total product cost); includes for the following: general plant

upkeep and overhead, payroll overhead, packaging, medical services, safety and

protection,restaurants, recreation, salvage, laboratories, and storage facilities.

Consider the plant overhead cost = 10% of Total Product Cost

Plant overhead cost = 10% of 6.8181 x106

= Rs. 0.68181 x106

Thus, Manufacturing cost = Direct production cost + Fixed charges + Plant overhead

costs

Manufacture cost = (4.1236 x106) + (1.022715 x106) + (0.68181 x106)

Manufacture cost = Rs. 5.828125 x106

(II) General Expenses = Administrative costs + distribution and selling costs +

research and development costs

(A) Administrative costs:(2-6% of total product cost)

Consider the Administrative costs = 5% of total product cost

Administrative costs = 0.05 x 6.8181x 106

Administrative costs = Rs. 0.3409 x 106

(B) Distribution and Selling costs: (2-20% of total product cost); includes costs for

sales offices, salesmen, shipping, and advertising.

Consider the Distribution and selling costs = 15% of total product cost

Distribution and selling costs = 15% of 6.8181 x106

= 0.15 x 6.8181 x106

= Rs. 1.02275 x106

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(C) Research and Development costs: (about 5% of total product cost)

Consider the Research and development costs = 5% of total product cost

Research and Development costs = 5% of 34.07 x 106

= 0.05 x6.8181 x106

= Rs. 0.3409 x106

(D) Financing (interest): (0-10% of total capital investment)

Consider interest = 5% of total capital investment

i.e. interest = 5% of 8.6694 x 106 = 0.05 x8.6694x 106

= Rs. 0.4334.7 x106

Thus, General Expenses = Rs. 2.1379 x 106

(III) Total Product cost = Manufacture cost + General Expenses

= (5.828125 x 106) + (2.1379 x106)

Therefore Total product cost = Rs. 7.96604 x106

Gross Earnings/Income:

Wholesale Selling Price of cane sugar per T = Rs. 8000 /-

As we know sugar factory operates only 120 - 200 days in a year and the production

of cane sugar per hour is 26.4818 T per hour (from material balance).

The working hours per day are 20.

Assuming factory operates only 150 days in a year.

Total Income = Selling price per T x Quantity of product manufactured (T/year)

= 8000 x (11.395) T/day x 150 days/year

Total Income = Rs. 13.614 x106

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Gross income = Total Income – Total Product Cost

= (Rs. 13.614 x106) – (Rs. 7.96604 x106)

Gross Income = Rs. 5.64796 x106

Let the Tax rate be 40%.

Taxes = 40% of Gross income

= 40% of Rs. 5.64796 x106 = 0.40 x Rs. 5.64796 x106

Taxes = Rs. 2.25184 x106

Net Profit = Gross income - Taxes = Gross income x (1- Tax rate)

Net profit = (Rs. 5.64796 x106 ) x ( Rs. 2.25184 x106 ) = Rs. 3.3887 x106

Rate of Return:

Rate of return = (Net profit x100)/ Total Capital Investment

Rate of Return = (Rs. 3.3887 x106 x100)/ (8.6694 x106 )

Rate of Return = 39.088%

Payout period = (FCI)/(Net profit + Depreciation)

= (7.5509 x106)/( 3.3887 x106 +0.7693 x106)

= 2 years

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10. PLANT LOCATION AND SITE SELECTION

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PLANT LOCATION AND SITE SELECTON

The geographical location of the final plant can have strong influence on the success

of the industrial venture. Considerable care must be exercised in selecting the plant

site, and many different factors must be considered. Primarily the plant must be

located where the minimum cost of production and distribution can be obtained but

other factors such as room for expansion and safe living conditions for plant operation

as well as the surrounding community are also important. The location of the plant

can also have a crucial effect on the profitability of a project. The choice of the final

site should first be based on a complete survey of the advantages and disadvantages of

various geographical areas and ultimately, on the advantages and disadvantages of the

available real estate. The various principal factors that must be considered while

selecting a suitable plant site are briefly discussed in this section. The factors to be

considered are:

1. Raw material availability

2. Location (with respect to the marketing area)

3. Availability of suitable land

4. Transport facilities

5. Availability of labors

6. Availability of utilities (Water, Electricity)

7. Environmental impact and effluent disposal

8. Local community considerations

9. Climate

10. Political strategic considerations

11. Taxations and legal restrictions

Raw Materials Availability:

The source of raw materials is one of the most important factors influencing

the selection of a plant site. This is particularly true for the cane sugar plant because a

large volume of sugar cane is consumed in the process, which will result in the

reduction of the transportation and storage charges. Attention should be given to the

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purchased price of the raw materials, distance from the source of supply, freight and

transportation expenses, availability and reliability of supply, purity of raw materials

and storage requirements.

Location:

The location of markets or intermediate distribution centers affects the cost

ofproduct distribution and time required for shipping. Proximity to the major markets

is an important consideration in the selection of the plant site, because the buyer

usually finds advantageous to purchase from near-by sources.

Availability Of Suitable Land:

The characteristics of the land at the proposed plant site should be examined

carefully. The topography of the tract of land structure must be considered, since

either or both may have a pronounced effect on the construction costs. The cost of the

land is important, as well as local building costs and living conditions. Future changes

may make it desirable or necessary to expand the plant facilities. The land should be

ideally flat, well drained and have load-bearing characteristics. A full site evaluation

should be made to determine the need for piling or other special foundations

Transport:

The transport of materials and products to and from plant will be an overriding

consideration in site selection. If practicable, a site should be selected so that it is

close to at least two major forms of transport: road, rail, waterway or a seaport. Road

transport is being increasingly used, and is suitable for local distribution from a

central warehouse.Rail transport will be cheaper for the long-distance transport. If

possible the plant site should have access to all three types of transportation. There is

usually need for convenient rail and air transportation facilities between the plant and

the main company head quarters, and the effective transportation facilities for the

plant personnel are necessary.

Availability Of Labors:

Labors will be needed for construction of the plant and its operation. Skilled

construction workers will usually be brought in from outside the site, but there should

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be an adequate pool of unskilled labors available locally; and labors suitable for

training to operate the plant. Skilled tradesmen will be needed for plant maintenance.

Local trade union customs and restrictive practices will have to be considered when

assessing the availability and suitability of the labors for recruitment and training.

Availability Of Utilities:

The word “utilities” is generally used for the ancillary services needed in

theoperation of any production process. These services will normally be supplied

from acentral facility and includes Water, Fuel and Electricity which are briefly

described as follows:

Water: - The water is required for large industrial as well as general purposes,

starting with water for cooling, washing and steam generation. The plant therefore

must be located where a dependable water supply is available namely lakes, rivers,

wells, seas.If the water supply shows seasonal fluctuations, it’s desirable to construct

a reservoir or to drill several standby wells. The temperature, mineral content, slit and

sand content, bacteriological content, and cost for supply and purification treatment

must also be considered when choosing a water supply. De-mineralized water, from

which all the minerals have been removed, is used where pure water is needed for the

process use, in boiler feed. Natural and forced draft cooling towers are generally used

to provide the cooling water required on site.

Electricity: - Power and steam requirements are high in most industrial plants

and fuel is ordinarily required to supply these utilities. Power, fuel and steam are

required forrunning the various equipments like generators, motors, turbines, plant

lightings and general use and thus be considered, as one major factor is choice of

plant site.

Environmental Impact And Effluent Disposal:

Facilities must be provided for the effective disposal of the effluent without

any public nuisance. In choosing a plant site, the permissible tolerance levels for

various effluents should be considered and attention should be given to potential

requirements for additional waste treatment facilities. As all industrial processes

produce waste products, full consideration must be given to the difficulties and coat

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of their disposal. The disposal of toxic and harmful effluents will be covered by local

regulations, and the appropriate authorities must be consulted during the initial site

survey to determine the standards that must be met.

Local Community Considerations:

The proposed plant must fit in with and be acceptable to the local community.

Full consideration must be given to the safe location of the plant so that it does not

impose a significant additional risk to the community.

Climate:

Adverse climatic conditions at site will increase costs. Extremes of low

temperatures will require the provision of additional insulation and special heating for

equipment and piping. Similarly, excessive humidity and hot temperatures pose

serious problems and must be considered for selecting a site for the plant. Stronger

structures will be needed at locations subject to high wind loads or earthquakes.

Political And Strategic Considerations:

Capital grants, tax concessions, and other inducements are often given by

governments to direct new investment to preferred locations; such as areas of high

unemployment. The availability of such grants can be the overriding consideration in

site selection.

Taxation And Legal Restrictions:

State and local tax rates on property income, unemployment insurance, and

similar items vary from one location to another. Similarly, local regulations on

zoning, building codes, nuisance aspects and others facilities can have a major

influence on the final choice of the plant site.

PLANT LAYOUT

After the flow process diagrams are completed and before detailed

piping,structural and electrical design can begin, the layout of process units in a plant

and the equipment within these process unit must be planned. This layout can play an

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important part in determining construction and manufacturing costs, and thus must be

planned carefully with attention being given to future problems that may arise.

Thus the economic construction and efficient operation of a process unit will

depend on how well the plant and equipment specified on the process flow sheet is

laid out. The principal factors that are considered are listed below:

1. Economic considerations: construction and operating costs

2. Process requirements

3. Convenience of operation

4. Convenience of maintenance

5. Health and Safety considerations

6. Future plant expansion

7. Modular construction

8. Waste disposal requirements

Costs:

Adopting a layout that gives the shortest run of connecting pipe between

equipment, and least amount of structural steel work can minimize the coat of

construction. However, this will not necessarily be the best arrangement for operation

and maintenance.

Process Requirements:

An example of the need to take into account process consideration is the need

to elevate the base of columns to provide the necessary net positive suction head to a

pump.

Convenience Of Operation:

Equipment that needs to have frequent attention should be located convenient

to the control room. Valves, sample points, and instruments should be located at

convenient positions and heights. Sufficient working space and headroom must be

provided to allow easy access to equipment.

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Convenience Of Maintenance:

Heat exchangers need to be sited so that the tube bundles can be easily with

drawn for cleaning and tube replacement. Vessels that require frequent replacement of

catalyst or packing should be located on the out side of buildings. Equipment that

requires dismantling for maintenance, such as compressors and large pumps, should

be places under cover.

Health And Safety Considerations:

Blast walls may be needed to isolate potentially hazardous equipment, and

confine the effects of an explosion. At least two escape routes for operators must be

provided from each level in process buildings.

Future Plant Expansion:

Equipment should be located so that it can be conveniently tied in with any

future expansion of the process. Space should be left on pipe alleys for future needs,

and service pipes over-sized to allow for future requirements.

Modular Construction:

In recent years there has been a move to assemble sections of plant at the plant

manufacturer’s site. These modules will include the equipment, structural steel, piping

and instrumentation. The modules are then transported to the plant site, by road or

sea.

The advantages of modular construction are:

1. Improved quality control

2. Reduced construction cost

3. Less need for skilled labors on site

The disadvantages of modular construction are:

1. Higher design costs & more structural steel work

2. More flanged constructions & possible problems with assembly, on site

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BIBLIOGRAPHY

1. M.GOPALA RAO, MARSHALL SITTIG, OUTLINES OF CHEMICAL

TECHNOLOGY, 3RD EDITION, Pg No 314 – 319

2. Dr. G.K. ROY, SOLVED EXAMPLES IN CHEMICAL ENGINEERING,

KHANNA PUBLISHERS, Pg No 285 – 297

3. KIRK & OTHMER, ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY,

Vol 19, Pg No 151-233

4. ULLMAN, ENCYCLOPEDIA OF INDUSTRIAL CHEMISTRY, Vol .A 25,

Pg No 393-407

5. HUGOTE, HANDBOOK OF CANE SUGAR ENGINEERING

6. SUDHAKAR VASUDEO KARMARKAR, INTRODUCTION TO CANE

SUGAR TECHNOLOGY

7. R.H. PERRY AND DON W. GREEN, PERRY’S CHEMICAL ENGINEER’S

HAND BOOK, Mc GRAW HILL INTERNATIONAL EDITION, VOLUME

– 6

8. R. K. SINNOTT, BUTTER WORTH-HEINEMANN, COULSON AND

RICHARDSON’S CHEMICAL ENGINEERING SERIES, 3RD EDITION,

VOLUME – 6

9. JOSHI M .V, PROCESS EQUIPMENT DESIGN, MC-MILLAN INDIA

LTD, 2ND EDITION

Manufacture of Sugar

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