Contents

Syllabus ................................................................................................................................................... 1

Module: 1 ............................................................................................................................................... 1

Lecture: 1 ............................................................................................................................................ 1

HEAVY AND FINE CHEMICALS ......................................................................................................... 1

OVERVIEW ................................................................................................................................... 1

Classification ........................................................................................................................... 1

UNIT OPERATION AND UNIT PROCESS.................................................................................... 3

Module: 2 ............................................................................................................................................... 7

Lecture: 2 ............................................................................................................................................ 7

CARBON DIOXIDE ............................................................................................................................ 7

INTRODUCTION ........................................................................................................................... 7

SOURCES OF CO2 ......................................................................................................................... 8

MANUFACTURE ........................................................................................................................... 8

METHODS OF RECOVERY ............................................................................................................ 9

1. Girbotol amine process ................................................................................................. 10

2. Sodium carbonate process ............................................................................................ 10

3. Potassium carbonate process ....................................................................................... 11

PURIFICATION ........................................................................................................................... 12

1. Purification of low % CO2 containing gas ...................................................................... 12

2. Purification of high % CO2 containing gas ..................................................................... 12

PROPERTIES ............................................................................................................................... 13

USES .......................................................................................................................................... 13

Module: 2 ............................................................................................................................................. 14

Lecture: 3 .......................................................................................................................................... 14

OXYGEN AND NITROGEN .............................................................................................................. 14

INTRODUCTION ......................................................................................................................... 14

Oxygen .................................................................................................................................. 14

Nitrogen ................................................................................................................................ 15

MANUFACTURE ......................................................................................................................... 18

Linde's process (O2 and N2) ................................................................................................... 18

PROPERTIES ............................................................................................................................... 24

Oxygen .................................................................................................................................. 24

Nitrogen ................................................................................................................................ 24

USES .......................................................................................................................................... 24

Oxygen .................................................................................................................................. 24

Nitrogen ................................................................................................................................ 24

Module: 2 ............................................................................................................................................. 25

Lecture: 4 .......................................................................................................................................... 25

HYDROGEN .................................................................................................................................... 25

INTRODUCTION ......................................................................................................................... 25

MANUFACTURE ......................................................................................................................... 26

1. Electrolytic Process ....................................................................................................... 26

2. Lane process or steam hydrogen process ..................................................................... 28

Module: 2 ............................................................................................................................................. 30

Lecture: 5 .......................................................................................................................................... 30

HYDROGEN (Continued) ................................................................................................................ 30

3. Steam Hydrocarbon Process ......................................................................................... 30

4. Liquefaction of coke oven gas or coal gas..................................................................... 33

5. Bosch Process ................................................................................................................ 34

PROPERTIES ............................................................................................................................... 34

USES .......................................................................................................................................... 34

Module: 2 ............................................................................................................................................. 36

Lecture: 6 .......................................................................................................................................... 36

AMMONIA ..................................................................................................................................... 36

INTRODUCTION ......................................................................................................................... 36

MANUFACTURE ......................................................................................................................... 36

(a) Haber and Bosch Process .......................................................................................... 36

(c) Modified Haber Bosch process ................................................................................. 41

PROPERTIES ............................................................................................................................... 45

USES .......................................................................................................................................... 45

Module: 2 ............................................................................................................................................. 46

Lecture: 7 .......................................................................................................................................... 46

ACETYLENE .................................................................................................................................... 46

INTRODUCTION ......................................................................................................................... 46

MANUFACTURE ......................................................................................................................... 46

1. From calcium carbide .................................................................................................... 47

2. From paraffin hydrocarbons by pyrolysis (Wulff process) ............................................ 49

3. From natural gas by partial oxidation (Sachasse process) ............................................ 51

PROPERTIES ............................................................................................................................... 53

USES .......................................................................................................................................... 53

Module: 3 ............................................................................................................................................. 54

Lecture: 8 .......................................................................................................................................... 54

SODIUM CHLORIDE ....................................................................................................................... 54

INTRODUCTION ......................................................................................................................... 54

SOURCES OF SODIUM CHLORIDE .............................................................................................. 54

MANUFACTURE ......................................................................................................................... 55

1. Solar Evaporation .......................................................................................................... 55

2. Artificial Evaporation..................................................................................................... 57

3. Freezing Method ........................................................................................................... 58

PROPERTIES ............................................................................................................................... 58

USES .......................................................................................................................................... 58

Module: 3 ............................................................................................................................................. 60

Lecture: 9 .......................................................................................................................................... 60

SODIUM CARBONATE.................................................................................................................... 60

INTRODUCTION ......................................................................................................................... 60

MANUFACTURE ......................................................................................................................... 60

1. Leblanc process ............................................................................................................. 60

2. Solvay's ammonia soda process .................................................................................... 62

Module: 3 ............................................................................................................................................. 70

Lecture: 10 ........................................................................................................................................ 70

SODIUM CARBONATE (continued) ................................................................................................ 70

3. Dual process .................................................................................................................. 70

4. Electrolytic process ........................................................................................................... 72

PROPERTIES ............................................................................................................................... 74

USES .......................................................................................................................................... 74

Module: 3 ............................................................................................................................................. 75

Lecture: 11 ........................................................................................................................................ 75

SODIUM BICARBONATE ................................................................................................................ 75

INTRODUCTION ......................................................................................................................... 75

MANUFACTURE ......................................................................................................................... 75

PROPERTIES ............................................................................................................................... 77

USES .......................................................................................................................................... 78

Module: 3 ............................................................................................................................................. 79

Lecture: 12 ........................................................................................................................................ 79

SODIUM HYDROXIDE..................................................................................................................... 79

INTRODUCTION ......................................................................................................................... 79

TYPE OF CELLS ........................................................................................................................... 79

Hooker cells ........................................................................................................................... 80

Nelson cell ............................................................................................................................. 81

The Castner Kellner cell......................................................................................................... 82

Membrane cell ...................................................................................................................... 83

Module: 3 ............................................................................................................................................. 85

Lecture: 13 ........................................................................................................................................ 85

SODIUM HYDROXIDE (Continued) ................................................................................................ 85

MANUFACTURE ......................................................................................................................... 85

1. Using Diaphragm cell .................................................................................................... 85

Module: 3 ............................................................................................................................................. 89

Lecture: 14 ........................................................................................................................................ 89

SODIUM HYDROXIDE (Continued) ................................................................................................ 89

2. Lime soda process ......................................................................................................... 89

PROPERTIES ............................................................................................................................... 92

USES .......................................................................................................................................... 92

Module: 3 ............................................................................................................................................. 93

Lecture: 15 ........................................................................................................................................ 93

CHLORINE ...................................................................................................................................... 93

INTRODUCTION ......................................................................................................................... 93

MANUFACTURE ......................................................................................................................... 93

1. Using diaphragm cells ................................................................................................... 93

2. Deacon’s method .......................................................................................................... 93

3. Other methods .............................................................................................................. 94

PROPERTIES ............................................................................................................................... 94

USES .......................................................................................................................................... 95

Module: 4 ............................................................................................................................................. 96

Lecture: 16 ........................................................................................................................................ 96

NITRIC ACID ................................................................................................................................... 96

INTRODUCTION ......................................................................................................................... 96

MANUFACTURE ......................................................................................................................... 96

1. From Chile saltpeter or nitrate ..................................................................................... 96

2. Arc process or Birkeland and eyde process .................................................................. 98

3. Ostwald's process or Ammonia oxidation process ....................................................... 99

PROPERTIES ............................................................................................................................. 105

USES ........................................................................................................................................ 106

Module: 4 ........................................................................................................................................... 107

Lecture: 17 ...................................................................................................................................... 107

SULFURIC ACID ............................................................................................................................ 107

INTRODUCTION ....................................................................................................................... 107

MANUFACTURE ....................................................................................................................... 108

1. The lead chamber process .......................................................................................... 108

Module: 4 ........................................................................................................................................... 113

Lecture: 18 ...................................................................................................................................... 113

SULFURIC ACID (continued) ........................................................................................................ 113

2. The contact process for sulfuric acid .......................................................................... 113

PROPERTIES ............................................................................................................................. 119

USES ........................................................................................................................................ 120

Module: 4 ........................................................................................................................................... 121

Lecture: 19 ...................................................................................................................................... 121

HYDROCHLORIC ACID .................................................................................................................. 121

INTRODUCTION ....................................................................................................................... 121

MANUFACTURE ....................................................................................................................... 122

1. Synthesis from Hydrogen and Chlorine ...................................................................... 122

2. The Salt–Sulfuric acid process ..................................................................................... 125

3. As by-product from chemical processes ..................................................................... 126

4. From incineration of waste organics........................................................................... 126

5. From hydrochloric acid solutions ................................................................................ 127

PROPERTIES ............................................................................................................................. 127

USES ........................................................................................................................................ 127

Module: 4 ........................................................................................................................................... 129

Lecture: 20 ...................................................................................................................................... 129

PHOSPHOROUS ........................................................................................................................... 129

INTRODUCTION ....................................................................................................................... 129

PHOSPHATE ROCK ................................................................................................................... 130

YELLOW PHOSPHORUS ........................................................................................................... 132

RED PHOSPHORUS .................................................................................................................. 134

PROPERTIES ............................................................................................................................. 135

USES ........................................................................................................................................ 136

Module: 4 ........................................................................................................................................... 137

Lecture: 21 ...................................................................................................................................... 137

PHOSPHORIC ACID ...................................................................................................................... 137

INTRODUCTION ....................................................................................................................... 137

MANUFACTURE ....................................................................................................................... 137

1. Using phosphate rock and blast furnace .................................................................... 137

2. Using phosphate rock and electric furnace ................................................................ 140

3. Oxidation and Hydration of phosphorous .................................................................. 142

4. Wet process or from sulfuric acid and phosphate rock .............................................. 143

PROPERTIES ............................................................................................................................. 149

USES ........................................................................................................................................ 149

Module: 5 ........................................................................................................................................... 151

Lecture: 22 ...................................................................................................................................... 151

CEMENT INDUSTRIES .................................................................................................................. 151

INTRODUCTION ....................................................................................................................... 151

CLASSIFICATION ...................................................................................................................... 153

Module: 5 ........................................................................................................................................... 157

Lecture: 23 ...................................................................................................................................... 157

CEMENT CLASSIFICATION (Continued) ....................................................................................... 157

MANUFACTURE OF PORTLAND CEMENT ................................................................................ 158

Significance of constituents ................................................................................................ 159

Module: 5 ........................................................................................................................................... 161

Lecture: 24 ...................................................................................................................................... 161

CEMENT MANUFACTURE ............................................................................................................ 161

MANUFACTURE ....................................................................................................................... 161

PROPERTIES ............................................................................................................................. 170

Module: 5 ........................................................................................................................................... 171

Lecture: 25 ...................................................................................................................................... 171

CEMENT (Continued) .................................................................................................................. 171

CHEMICAL COMPOSITION ....................................................................................................... 171

PHYSICAL REQUIREMENT ........................................................................................................ 171

SETTING AND HARDENING OF CEMENT ................................................................................. 172

USES ........................................................................................................................................ 174

Module: 6 ........................................................................................................................................... 175

Lecture: 26 ...................................................................................................................................... 175

CERAMIC INDUSTRIES ................................................................................................................. 175

INTRODUCTION ....................................................................................................................... 175

CLASSIFICATION ...................................................................................................................... 175

RAW MATERIAL ....................................................................................................................... 176

PROPERTIES ............................................................................................................................. 177

USES ........................................................................................................................................ 177

Module: 6 ........................................................................................................................................... 178

Lecture: 27 ...................................................................................................................................... 178

WHITEWARES .............................................................................................................................. 178

1. Whitewares ..................................................................................................................... 178

classification ............................................................................................................................ 178

Manufacture ........................................................................................................................... 179

Properties ................................................................................................................................ 181

Uses ......................................................................................................................................... 181

Module: 6 ........................................................................................................................................... 182

Lecture: 28 ...................................................................................................................................... 182

CLAY PRODUCTS AND REFRACTORIES ......................................................................................... 182

2. STRUCTURAL CLAY PRODUCTS ........................................................................................ 182

PROPERTIES ............................................................................................................................. 183

USES ........................................................................................................................................ 183

3. REFRACTORY MATERIALS ................................................................................................ 184

CLASSIFICATION ...................................................................................................................... 184

MANUFACTURE ....................................................................................................................... 186

PROPERTIES ............................................................................................................................. 188

USES ........................................................................................................................................ 191

Module: 6 ........................................................................................................................................... 193

Lecture: 29 ...................................................................................................................................... 193

SPECIALIZED CERAMIC PRODUCTS AND VITREOUS ENAMEL ..................................................... 193

4. SPECIALIZED CERAMIC PRODUCTS .................................................................................. 193

5. VITREOUS ENAMEL ......................................................................................................... 195

MANUFACTURE ....................................................................................................................... 195

PROPERTIES ............................................................................................................................. 196

USES ........................................................................................................................................ 196

Module: 7 ........................................................................................................................................... 197

Lecture: 30 ...................................................................................................................................... 197

GLASS INDUSTRIES ...................................................................................................................... 197

INTRODUCTION ....................................................................................................................... 197

TYPES OF GLASSES ................................................................................................................... 197

Module: 7 ........................................................................................................................................... 203

Lecture: 31 ...................................................................................................................................... 203

MANUFACTURE OF GLASS .......................................................................................................... 203

RAW MATERIAL ....................................................................................................................... 203

MANUFACTURE ....................................................................................................................... 204

Module: 7 ........................................................................................................................................... 207

Lecture: 32 ...................................................................................................................................... 207

GLASS (Continued) ...................................................................................................................... 207

MANUFACTURE (Continued) ................................................................................................... 207

PROPERTIES ............................................................................................................................. 209

Module: 8 ........................................................................................................................................... 211

Lecture: 33 ...................................................................................................................................... 211

FERTILIZER ................................................................................................................................... 211

INTRODUCTION ....................................................................................................................... 211

TYPES OF SOIL ......................................................................................................................... 211

PLANT NUTRIENTS .................................................................................................................. 212

FUNCTION OF NUTRIENT ........................................................................................................ 212

NEED OF FERTILIZER ................................................................................................................ 215

CLASSIFICATION ...................................................................................................................... 215

Module: 8 ........................................................................................................................................... 220

Lecture: 34 ...................................................................................................................................... 220

AMMONIUM PHOSPHATE........................................................................................................... 220

INTRODUCTION ....................................................................................................................... 220

MANUFACTURE ....................................................................................................................... 221

PROPERTIES ............................................................................................................................. 223

USES ........................................................................................................................................ 224

Module: 8 ........................................................................................................................................... 225

Lecture: 35 ...................................................................................................................................... 225

SUPERPHOSPHATE ...................................................................................................................... 225

INTRODUCTION ....................................................................................................................... 225

MANUFACTURE ....................................................................................................................... 226

PROPERTIES ............................................................................................................................. 232

USES ........................................................................................................................................ 232

Module: 8 ........................................................................................................................................... 233

Lecture: 36 ...................................................................................................................................... 233

TRIPLE SUPERPHOSPHATE .......................................................................................................... 233

INTRODUCTION ....................................................................................................................... 233

MANUFACTURE ....................................................................................................................... 234

PROPERTIES ............................................................................................................................. 238

USES ........................................................................................................................................ 238

Module: 9 ........................................................................................................................................... 239

Lecture: 37 ...................................................................................................................................... 239

UREA............................................................................................................................................ 239

INTRODUCTION ....................................................................................................................... 239

MANUFACTURE ....................................................................................................................... 240

PROPERTIES ............................................................................................................................. 244

USES ........................................................................................................................................ 245

Module: 9 ........................................................................................................................................... 246

Lecture: 38 ...................................................................................................................................... 246

CALCIUM AMMONIUM NITRATE ................................................................................................ 246

INTRODUCTION ....................................................................................................................... 246

MANUFACTURE ....................................................................................................................... 246

PROPERTIES ............................................................................................................................. 249

USES ........................................................................................................................................ 249

Module: 9 ........................................................................................................................................... 250

Lecture: 39 ...................................................................................................................................... 250

AMMONIUM CHLORIDE .............................................................................................................. 250

INTRODUCTION ....................................................................................................................... 250

MANUFACTURE ....................................................................................................................... 251

1. Direct reaction ............................................................................................................ 251

2. Duel salt process ......................................................................................................... 252

USES ........................................................................................................................................ 254

Module: 9 ........................................................................................................................................... 256

Lecture: 40 ...................................................................................................................................... 256

AMMONIUM SULFATE ................................................................................................................ 256

INTRODUCTION ....................................................................................................................... 256

MANUFACTURE ....................................................................................................................... 257

PROPERTIES ............................................................................................................................. 261

USES ........................................................................................................................................ 261

Module: 10 ......................................................................................................................................... 262

Lecture: 41 ...................................................................................................................................... 262

POTASSIUM CHLORIDE................................................................................................................ 262

INTRODUCTION ....................................................................................................................... 262

MANUFACTURE ....................................................................................................................... 262

PROPERTIES ............................................................................................................................. 264

USES ........................................................................................................................................ 264

Module: 10 ......................................................................................................................................... 265

Lecture: 42 ...................................................................................................................................... 265

POTASSIUM SULFATE .................................................................................................................. 265

INTRODUCTION ....................................................................................................................... 265

MANUFACTURE ....................................................................................................................... 265

1. Mannheim process ...................................................................................................... 265

2. Recovery from natural complex salts ......................................................................... 267

PROPERTIES ............................................................................................................................. 268

USES ........................................................................................................................................ 268

Module: 11 ......................................................................................................................................... 270

Lecture: 43 ...................................................................................................................................... 270

PAINT INDUSTRIES ...................................................................................................................... 270

INTRODUCTION ....................................................................................................................... 270

CLASSIFICATION OF PAINTS .................................................................................................... 270

Module: 11 ......................................................................................................................................... 274

Lecture: 44 ...................................................................................................................................... 274

PAINT INDUSTRIES (continued) ................................................................................................... 274

CONSTITUENTS OF PAINTS ...................................................................................................... 274

Module: 11 ......................................................................................................................................... 279

Lecture: 45 ...................................................................................................................................... 279

PAINT INDUSTRIES (continued) ................................................................................................... 279

MANUFACTURE ....................................................................................................................... 279

SETTING OF PAINT ................................................................................................................... 282

REQUIREMENT OF A GOOD PAINT .......................................................................................... 283

PAINT FALIURE ........................................................................................................................ 284

PROPERTIES ............................................................................................................................. 285

1

Syllabus

Curriculum of the subject is divided into eleven modules and 45 lectures.

Module No. Lecture

Numbers

Topics to be covered

Module No. 1 1 Overview

Introduction, classification of chemical industries,

heavy and fine chemicals

Module No. 2 2 – 7 Industrial Gases

Introduction, manufacture and uses of carbon

dioxide, nitrogen, oxygen, hydrogen, ammonia,

acetylene.

Module No. 3 8 – 15 Sodium compounds

Sources, uses and preparation of sodium chloride.

Manufacture, properties and uses of sodium

carbonate, sodium bicarbonate sodium hydroxide

and chlorine.

Module No. 4 16 – 21 Mineral acids

Manufacture, properties and uses of nitric acid,

sulfuric acid, hydrochloric acid, phosphorus and

phosphoric acid

Module No. 5 22 – 25 Cement Industries

Raw materials, manufacturing method, types of

cement

Module No. 6 26 – 29 Ceramic Industries

Raw materials, manufacturing methods and

properties of white wares, clay products, refractories.

Module No. 7 30 – 32 Glass Industries

Raw materials, manufacture of glass, types of glass

Module No. 8 33 – 37 Phosphorus based agrochemicals

Introduction of fertilizers. Synthesis, properties and uses

of ammonium phosphate, super phosphate, triple

super phosphate.

Module No. 9 38 – 40 Nitrogen fertilizers

Introduction, manufacture & properties of urea,

ammonium chloride, calcium ammonium nitrate

(CAN), ammonium sulfate

Module No. 10 41 - 42 Potassium fertilizers

Introduction manufacture and properties of potassium

chloride and potassium sulfate

Module No. 11 43 – 45 Paint Industries

Introduction, types, manufacture and properties of

paints

Jay Shri Harsiddhi Mataji Module 1 Lecture: 1 Overview

Dr. N. K. Patel

N P T E L

1

Module: 1

Lecture: 1

HEAVY AND FINE CHEMICALS

OVERVIEW

Chemical industries are basically divided into two groups.

First which produces simple compounds from the locally available large

amount of raw materials usually they are very large industries and the product

manufacture are purified to the extent that they can be used as raw material for

other industries or they are directly marketed as a consumer goods. In general they

are heavy chemical industries.

On the other hand certain industries deal with speciality chemicals and they

are making small quantity of product having better quality which is sold into market

as finished good. They are called as fine chemical industries.

Classification

The materials used or produced in the chemical industries are classified in the

following manner.

1. Quantity of production and consumption

a) Heavy chemicals

Those dealt in large quantity normally crude or less purified chemicals.

E.g. mineral acid, NaOH, Na2CO3 etc.

b) Fine chemicals

They are complete purified substances and produced in limited quantity.

E.g. speciality solvent, perfumes, medicines etc.

2. Chemical composition

a) Organic compound

Compounds having carbon atom in the main structure of the molecule is

called organic compound.

E.g. hydrocarbons, phenols, carboxylic acid etc.

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b) Inorganic compound

They are the compounds which do not have carbon in the main structure.

E.g.Na2CO3, K2Cr2O7, MgCl2

c) Polymers

They are the macromolecular mass compounds made from covalent

bonding of repeating structured units which may be natural, synthetic or semi

synthetic. E.g. polystyrene, polyvinylchloride etc.

3. Based on availability

a) Natural compounds

Compounds which are available in nature or produced or extracted from

plant and animals are referred as natural products. Due to large utilization & limited

production the natural source is depleting. E.g. coal, petroleum etc.

b) Synthetic products

Men made compounds are referred as synthetic products. They may be

synthesized using natural product or they are synthesized completely using other

type of synthetic materials, but the main target or such product is that must be

suited to direct applications.

4. Based on application

a) Catalyst

A substance, usually used in small amounts relative to the reactants, that

either increases or decreases the rate of a reaction without being consumed in the

process. If consumed than it should regenerative at the end of process. E.g. AlCl3,

MnO2, Pt etc.

b) Bulk drug

Bulk drug is the active substance used in a drug formulation. It becomes an

active ingredient of a finished dosage form of the drug, but the term does not

include intermediates used in the synthesis of such substances. E.g. Pantoprazole,

Bisacodyl etc.

c) Resin

Resin is a natural or synthetic compound which begins in a highly viscous

state and hardness with treatment.

E.g. Urea formaldehyde, epoxy, polyester etc.

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d) Dyes and Pigments

A dye or a dyestuff is usually a coloured organic compound or mixture that

may be used for imparting colour to a substrate such as cloth, paper, plastic or

leather in a reasonably permanent fashion.

Pigments are defined as colouring agents that are practically insoluble in the

application medium, whereas dyes are colouring agents that are soluble in the

application medium.

Many organic pigments and dyes have the same basic chemical structure.

The insolubility required in pigments can be obtained by excluding solubilizing

groups, by forming insoluble salts (lake formation) of carboxylic or sulfonic acids, by

metal complex formation in compounds without solubilizing groups, and particularly

by incorporating groups that reduce solubility (e.g. amide groups).

e) Solvent

A liquid in which substances (or solutes) are dissolved to form a solution is

called as solvent.

E.g. Benzene, THF, DMF, DMSO etc.

f) Miscellaneous

All other compounds which do not cover in above class are called as

miscellaneous.

E.g. fertilizer, glass etc.

UNIT OPERATION AND UNIT PROCESS

Activities of chemical manufacturing plant are broadly covered under the

label of conversion of raw materials into useful products. In some cases the product

are used as starting materials for further modification and thus the product may not

be termed as end product but is called as intermediate. In another cases the

products are ready for marketing known as finished product. But still some of the

finished products may be used for physical blending or combination with other

materials and binders particularly in pharmaceutical industries.

Form the above discussion materials which are used in chemical industries

can be classified into following categories.

Raw materials

They are naturally occurring material or not produced at the manufacturing

unit and are procured from outside the manufacturing plant.

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Intermediate

They are undergoes some processing and further proceed for modification

Finished product

Product which are ready for marketing or sale

By product

It is useful material generated with main product. Also known as co-product

Waste

Do not have any commercial value. May be discarded after giving some

treatments regarding control of pollution.

Further, any commercial manufacture or production unit of chemicals have

combination of series of physical and chemical changes of raw materials or

intermediates or finished product. Ultimately comprehensive utilization of material for

improvement in chemical properties, modification of chemicals, maximize the yield

and conversion, utilization of waste products etc.

For the systematic study of chemical process industries the physical and

chemical changes which are important for the manufacturing processes have been

classified as unit operation and unit processes respectively

Thus,

Chemical Process Industries = Unit operation + Unit process

Unit operation

Major physical changes occur which are useful to chemical industries are

known as unit operation. In majority of cases, operations are to be done to set up

the condition to carry out chemical changes. Thus very important classification of

various changes useful to chemical industries was needed to be done.

Unit operations shall be broadly classified as follows.

1. Fluid flow processes : Fluids transportation, filtration, solids

fluidization

2. Heat transfer processes : Evaporation, condensation

3. Mass transfer processes : Gas absorption, distillation, extraction,

adsorption, drying

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4. Thermodynamic processes : Gas liquefaction, refrigeration

5. Mechanical processes : Solids transportation, crushing and

pulverization, screening and sieving

6. Combination : Mixing

7. Separation : Distillation, extraction

Unit process

Useful chemical transformations with or without physical changes occurs in

the chemical industries are called as unit process e.g. halogenations, oxidation,

reduction, alkylation and acylation etc.

The study of these processes includes

The basic knowledge of chemistry and mechanism of particular chemical

reaction

Design of equipment for the reaction

Optimization of reaction parameter

However, still the condition and parameter for carrying unit process in plant

level may differ from product to product. But the regularities emerged from the study

of a particular process can be useful in setting up condition for the manufacture of

new chemical which may include one or more such unit processes.

E.g. In the unit process nitration

Reaction is almost exothermic

Physicochemical principles of equilibrium and chemical kinetics are similar

Material of construction of plant and equipment for the process can be

predicted

The principles of widely varying sequence of making up a chemical process

do not depend upon the nature of the materials being worked upon and other

characteristic of the system under study. If the step of process is recognized, the

process can be designed in such a way that each step to be used can be studied

individually.

In both unit operations and unit processes the similarities within any unit

operation or unit process are separated and studied; thus drawing attention to the

like qualities of a given physical change or chemical change. Finally these results

help to understanding the process, establishment of reaction parameter and

reactor design. This is the scientific and engineering approach. The ultimate study by

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this method of the technical changes culminated in chemical engineering formulas

and laws for using the classified observations in each unit operation or unit process.

These formulas and laws are the tools for the industrial chemist uses in designing or

operating a chemical plant.

In conclusion, Both physical and chemical changes have been useful not

only to fundamental concept but also to provide the technical detail as well as

smoothen the manufacturing process at optimized reaction condition at low cost.