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Chemical Technology

TOPIC 1: CHEMICAL PROCESSING, UNIT OPERATION &UNIT PROCESS

Chemical Process Selection, Design and Operation

Adequate and flexible initial design is essential for the promotion of a

chemical plant organic product or inorganic product.

In older days it was classified as inorganic chemical technology and organic

chemical technology. Subsequently the oxford university made it as chemicalworks organization and management.

Some factors that must be considered in planning a plant are discussed in this

section. The Process Engineer is an expert in the current aspects of chemical

process design. Practical experience is a must if the senior design engineer is

able to foresee and solve the problems of production, such as maintenance,

safety and obeying the government, environmental by loss and control.

Experience consultants either individuals or professional consulting firms are

able to advise, design and for erection of chemical plants.

Chemical Process Control and Instrumentation

Automatic and Instrument control chemical processes are common and

essential. Instruments should not be chosen simply to record a variables, of

the process. But their function is to assure consistent quality by sensing

controls, recording and maintaining desired operating conditions. Instruments

are the essential tool for modern processes. They are classified as

1. Indicating Instruments 2. Recording Instruments 3.

Controlling Instruments

Two types of Instruments are currently used as analogue and digital.

Analogue Instruments such as pressure spring thermometers and Bourden

Gauges shows results by mechanical moments of some type of device which isdirectly proportional to the quantity measured.

On the other hand, digital devices are converts the quantity measured into a

signal and electric circuits converts the signal to read the numerical values

forward by control. Now the computers can monitor and regulate outputs from

both the analogue and digital devices according to a prearranged program,

also general conventional digital inputs are required. Chemical analytical

control has been used in day to day factory procedures for analysis of

incoming raw material or outgoing products. Thus quality chemicals are

produced more in these days reliably their when human analysed control were

ical Technology - SD Senthil's Home Page https://sites.google.com/a/sdsenthil.com/www/chemical-te

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used.

The latest advancement are the chromatography system, many spectroscopy

have been automated an install of on-line basis for the process to run

continuously without the problems encountered manually before.

Role of Chemical Engineers

Chemical Engineers are trained primarily to work in chemical industries. some

of the vital role of the chemical engineers are as follows;

Chemical Process Economics

Engineer are totally different from Scientist by their customers of cost of

production and profit generator. Therefore the objective of engineer should be

to deliver safely the best product or most efficient service at lower cost to the

employer and the public who consumes the product.

Material Balance

Yield and conversion are the chemical prospects from the basis for the

material balances which is useful for cost determination.

Materials and their quantities from the standard practices are tabulated in the

flow charts, energy given are observed for the chemical reactions and energy

is frequently a major cost in chemical plants but it often possible by altering

the process procedures by using modern separation technologies like RO

and Advanced Separation Processes to produce high quality chemicals with

low energy consumption.

Plant Location

The location of the chemical plant is decided ourselves by the availability of

raw materials, transportation, market and power. Now the environmental

constituents, water supply, availability of efficient labor, cost of land and waste

disposal facilities form the criteria for the plant location.

Construction of Plant

For small and large companies construction engineering organizations are

available that will built a plant and participate in its design. Some large

chemical companies have their own civil construction department and starts

their own plants.

The advancement of this is the worker who is going to operate the equipment

can be more intimately corrected to the constructions and be familiar

themselves for the future alternatives, expansion or modifications.

In built-in plants the top engineers are chartered engineers qualified for the

development activities. They have been trained and suitably examined to

guarantee technical competency and owe personal responsibility. They are

now called as functional consultants and registered firm for dealing with legal

aspects with proper training.

Research and Development

adequate and skilled research with patent protection is necessary for future

profits. In the chemical process industries one of the outstanding tactics is

rapidly changing processes, new raw materials and new markets. Research


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creates these changes and the factory will have a competitive progress. This

research brings about development and the adoption of ideas, concepts,

methodologies form the production of the industry. The results and benefits of

research establishes the developing coutry on the road of progress and raise

the level of life of common man.

Chemical Engineer in coming years

Resources particularly energy and feed back for the Fertilizers and

Heavy Chemical Industries.

1.

Infrastructure for Transportation and Telecommunications.2.

Protection of the Environment.3.

Development of Agro Industries where utilization of waste from Agro

industries and exploitation of value added products from wastes.

4.

Transformation of Rural Economy, Industrialization and Privatization

where the profits are less and consumption is more.

5.

Problems of less Technical context are,6.

The Centre Vs. States

Command Economy Vs. Liberalisation & PrivatisationInternal Budget and External Balances

World Trade Globalization and relevant to IndiaProblem of Indian competitiveness

The latest research and development have classified the following new

industries;

Cryogenics in Chemical Technology1.

Chemicals from Sea2.

Air as a Chemical Raw Material3.

NUPLEXES ( Nuclear Power Agro Industrial Complexes )4.

Proteins from Petroleum Fermentation and Single Cell Proteins from

Animal horns.

5.

Food Industries6.

Coal Chemicals7.

Newer Petrochemicals8.

Pesticides9.

Pharmaceuticals Industries10.

Metallurgical Industries11.

Water treatment & Air Pollution Control12.

The chemical process industry had its growth from pre scientific chemical

industries followed by scientific chemical industry. The growth with restrains,

green challenge to chemical industry and the modern separations process

involved in the indian chemical industry seen today.

We define Chemical Engineering as a synthesis of chemistry and engineering.

A Chemical Engineering therefore carries out on a large scale reactions

developed in the laboratory by the chemist.

The Major Areas of Work within Chemical Engineering are,

Research

Process Development

Process Design

Evaluation of Design


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Plant Design

Construction

Production Supervision

Plant Technical Services

Sales of the Product

The Research is divided into three categories like Fundamental Research,

Exploratory Research and Process Research.

S.No. Industry Typical Products End User

1 Inorganic

Chemicals

H2SO4 Fertilizers,

Chemicals,

Petroleum Refining,

Paints, Pigments,

Metal Processing and

Explosives

HNO3 Explosives &

Fertilizers

NaOH Rayon, Film

Processing,

Petroleum Refining,

Pulp & Paper

Industry, Lye,

Cleaners, Soap &

Detergents, Metal

Processing

2 Organic Chemicals Acetic Anhydride Resins, Plastics &

Nylon

Ethyl Alcohol Antifreeze agents,

Cellophane,

Dynamite & Syn.

Fibres

Formaldehyde Plastics

Methanol Mfr. Of

Formaldehyde,

IMS(Industrial

Methylated Solvent)

& Antifreeze agent


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3 Petroleum&

Petrochemicals

Gasoline Motor Fuels

Kerosene Fuel

Oil Lubrication &

Heading purposes

Ammonia Fertilizer &

Chemicals

Ethanol Acetaldehyde

solvents & other

miscellaneous

chemicals

Alkyl Aryl Sulfonate Detergents

Styrene Syn. Rubber,

Polymers & Plastics

4 Pulp & Paper Paper Books, Records &

Newspaper

Cardboard Boxes for packing

Fiber Board Building materials

5 Pigments & Paints Zinc Oxide (ZnO) Pigments for paints,

inks, plastic, rubber,

ceramics and

linoleumTiO2

Carbon Blade Drying Oil

Lead Chromate

Linseed Oil

Phenolic Resins Basic kequer

warmish & enamels

Alkyl Resins Ion exchange resins

and constituents of

enamel


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6 Rubber Natural

Rubber(Isoprene)

Automobile tyres,

moulds, sheets,

footwear and

insulationSyn. Rubber

(Neoprene)

Butyl Rubber

7 Plastics Phenol Formaldehyde Various users in all

areas of everyday

lifePoly Styrene

Polymethyl

methacrylate

PVC

Polyethylene

Polyster

8 Synthetic Fibers Rayon Clothing

Nylon

Acrylics

Polyster

9 Minerals Glass & Ceramics Windows, containers,

bricks & pipe tubes

Cement Concrete for

construction of

buildings, highways,

etc.

Coal Fuels, coke and its

by-products

10 Cleansing Agents Soaps & Detergents House hold cleaning

& Industrial

cleaning. Sodium

alkyl aryl sulfonate

is also used as

wetting agent.


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11 Bio Chemicals Pharmaceuticals &

Drugs

Health & Medicine

applications

Fermentation product

like penicillin

Medical use

Ethyl Alcohol Solvent and

Beverages

Food Products Human sustance

12 Metals Steel, Cu, Al &

Zirconium

All the Building

materials, machinery

etc.

Uranium Nuclear fuel

The largest tonnage inorganic chemicals is H2SO4.It is consumed by industry

in the manufacture of other products. Thereby it reaches the public knowledge

vary scarely. Large quantities are consumed by petroleum and metal

industries. The important organic chemical include alcohols, dyes, dye

intermediates used to produce other chemicals. Ethyl alcohol was initially

produced by bio chemical fermentation before the second world war.

But now it is produced primarily from petroleum on the latest discovery of

natural gas. The important petroleum products are gasoline, lubricants,

petrochemicals, other fuels and miscellaneous chemicals. Since the second

world war petrochemicals have assumed a commander role in the economy.

The largest petrochemical ammonia is produced by reaction of H2from naturalgas or petroleum with N2available in the Air.

This Ammonia reacts with CO2to produce Urea in a fertilizer plant. Normally

there are five different units in the fertilizer manufacture from coal based

mines.

Oil & Gasification plant1.

Benfield De-sulphurization plant2.

Ammonia plant3.

CO2plant4.

Urea plant5.

The tendency of Urea is to form BIURETS which are used as regenerator salts

in the metallurgical applications. Many plastics and synthetic detergents are

produced with the help of oil refineries.

Unit Operation

The basic physical operations of chemical engineering in a chemical process

plant, that is distillation, fluid transportation, heat and mass transfer,

evaporation, extraction, drying, crystallization, filtration, mixing, size


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separation, crushing and grinding, and conveying. In simple terms, the

operation which involves physical changesare known as Unit Operation.

Distillation is a unit operation is used to purify or separate alcohol in the

brewery industry.

1.

The same distillation separates the hydrocarbon in a petroleum

industries.

2.

Dry grapes and other food products or similar drying of filter precipitatelike rayon industry where yarn is produced.

3.

Absorption of oxygen from air in a fermentation process of a sewage

treatment plant and half hydrogen gas in a process fr liquid

hydrogenation of oil.

4.

Evaporation of salts solutions similar to evaporation of sugar solution in

the industry.

5.

Settling and sedimentation of suspend solids similar to minimizing and

sewage treatment plant.

6.

Flow of liquid hydrocarbon in a petroleum refinery and flow of milk in adaily plant for the solidification in spray dryer.

7.

Classification of Unit Operations

Fluid Flow: Concerns the principle that determine the flow or

transformation of fluids from one point to another. The fluid can be a

liquid or a gas. This unit is entirely based on Bernoulli e's equation

followed by continuity correlation.

1.

Heat Transfer : Deals with principles that govern accumulation and

transfer of heat and energy from one place to another. The three

concepts followed here are conduction, convection and radiation.

2.

Evaporation: A special case of heat transfer which deals with the

evaporation of volatile solvent such as waste from a non-volatile solute

such as salt or any other material in the solution. The evaporation of

trichloro-ethylene a cleaning agent in the automobile service industry

and acetone in the case of glassware in a chemical process industries

follow this unit operations.

3.

Drying : An operation in which volatile liquids (usually water) are

removed from solid material.

4.

Distillation: An operation where a components of the liquid mixture

are separated by boiling because of their difference in vapor pressure.

5.

Absorption : A process whereby a component is removed from gas

mixture by treatment with liquid.

6.

Liq-Liq Extraction: A process in which a solute in a liquid solution is

removed by contact with another liquid solvent that is relatively

irreversible with solution.

7.

Liq-Solid Leaching: It involves treating a finely divided solid with a

liquid that dissolves and removes a solute contain in the solid.

8.

Crystallization: The removal of a solute such as a salt from solution

by precipitation in the industries for large scale operations, electrostatic

precipitation is operated for this concept.

9.

Mechanical physical separation: This involves separation of solids,10.


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liquids or gases by mechanical means such as filtration, settling, size

reduction which are classified as separate unit operations.

The outline of unit operation defines the settling tanks for

sedimentation, filter press for separations, pressurized spheres for

ammonia storage, pellatising for fertil izer compounds, pneumatic

conveyors for cement industry, bucket wheel elevators for

thermal power stations and belt conveyors for core industries and

many more in operation.

Stacks

Gases are discharged into the ambient atmosphere by stacks (referred to as

chimneys in industry) of several types.

The chemical process steps involved the following;

Preparing the Reactors1.

React them2.

Separate the Products3.

Purify the Products4.

The purpose of chemical industry is to start from one and other chemical raw

material arrive at a consumer product through a group of physical and

chemical products. Therefore it is called as a creative industry rather than

assembly industry.

This mainly fall into inorganic, natural products, organic chemicals and

metallurgical industry.

Unit Processes

Processes that involve making chemical changes to materials, as a result of

chemical reaction taking place. For instance, in the combustion of coal, the

entering and leaving materials are differ from each other chemically. Coal and

Air enters, and flue gases and residues leave the combustion chamber.

Combustion is therefore a unit process. Unit processes are also referred to as

chemical conversions. In simple terms, the process which involves chemical

changesare known as Unit Processes.

Together with unit operations (physical conversions), unit processes (chemical


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conversions) form the basic building blocks of a chemical manufacturing

process. Most chemical processes consist of a combination of various unit

operations and unit processes.

1. Alkylation:

Addition of alkyl radical (CH3) with side chain final product. This

alkylation process is widely used in organic chemicals and petroleumindustries. The reaction is given as,

C=C-C-C + C-C-C

2. Amination by Ammonolysis:

Cl-CH2CH2Cl + 4NH3------->NH2CH2CH2NH2 EDC Ethylene Diamine

This reaction is used in manufacture of dye stuffs, organic chemicals

and synthetic fibres.

3. Amination by Reduction:

CH3CHNO2CH3+ 3H2------>CH3CHNH2CH3 2 Nitro Paraffin Iso Propylamine

This unit process is also used in the manufacture of dye stuffs and

organic chemicals.

4. Amino Oxidation:

CH3CH

2CH

3+ NH

3+ 1.5 O

2----->CH

2:CHCN + H

20

Propylene Acrylonitrile

This reaction is used in the manufacture of plastics and synthetic

fibres.

5. Calcination:

CaCO3---Heat--->CaO + CO2

Limestone Lime

This reaction is used in the cement industry.

6. Carbonylation:

CH3OH + CO ----->CH3COOH

Methanol Acetic Acid

This is used in the manufacture of organic chemicals.

7. Carboxylation:


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This reaction is used in the organic chemical industry.

8. Combustion:

CH4+ O2------>CO2+ 2H2O ( Process Heating )

9. Condensation:

C6H5CHO + CH3CHO ------>C6H5CH:CHCHO + H2O Benzaldehyde+Acetaldehyde Cinnamaldehyde

10.Cracking or Pyrolysis:

C-C-C-C-C-C-C --------> C-C-C + C=C-C-C

This reaction is used in petroleum destruction and distillation of coal.

1. Fluid - Solid Contact:

Represented by fixed bed reaction. It is most widely used in catalytic

reactor used with precious metal catalyst to minimize attrition losses. The

catalyst used in the form of pellets. It can represented by the following figure.

This is used in the packed column. The design of the column is determined

by the breakthrough curve, equilibrium line for the given system of adsorbent

and adsorbate's. The volume of the reactant coming from the top and the

volume of which the product leaves the column, residence time, distribution

decides the dimensions of the column. It is contrary to the fluid bed reactor

where the bed is fluidized. Once the minimum fluidized velocity is reachedthe porosity of the bed is faster in a fixed bed reactor but varies from

the fluidized bed where the porosity changes according to the height of the

bed.

2. Fluid - Solid Separation:(Centrifugation)

This operation separates very finely divided solids from liquid or mixture of

liquid and liquid emulsion.


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3. Wet Scrubber:

It is an effective means of removing suspended particles from gas string by

contact with liquid shower.

When solids are used in the place of liquid the operation is called Dry

Scrubber. In the manufacture of MEK, wet scrubber is used and in

other selected process industries Dry Scrubbers are used,

Scrubber just washes away the impurities and separate the product for

further purification.

4. Filter Press:

It is the simplest type of pressure filtration. the two important parts of the

filter press are plates & frames and fabric used in between the two are made

of variety of corrosion resistant materials. In the laboratory scales asbestos

cloth are used for filtration at different pressures.

The operation decides the value of specific cake resistance, filter medium

resistance and compressibility of the chemical namely Kieselghur a specific

compound in the nature of diatomacceous earth which are used in the

application of bio-physics and cyrstallography.

5. Fluid Storage:

Tanks are widely used for storage of liquids of all types and atmospheric

pressure when the liquid is highly volatile there is a floating roof which acts

as lid for chemicals as and when the vapour pressure at which signifying the


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boiling point of liquid the roof changes its position and deserves the liquid

from going out to the atmosphere.

6. Pressurized Spheres:

Pressurized spheres are used for pressurized storage of liquefied gases or

high vapors. The pressure permits safe storage with no vapor losses. This is

seen in the fertilizer plant where ammonia is stored in spheres.

7. Gas-Liquid Contact: (Absorption)

The best example is Absorption. It is used for taking a soluble gas in a

solvent liquid and producing a solution plus an exit gas. Hydrogen Sulphide is

removed from hydrocarbon by the absorption process.


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8. Adsorption:

It is classified into physiorption and chemisorption according to the process

applied. The former one is almost a physical change or physical

transformation while a later represents a chemical reaction which is a

irreversible one. the common effluent treatment plants of varies nature lied

textile effluents, sewage treatment, ETP plants in chemical industry, removal

of hazardous solid wastes, etc are dealt with adsorption method and

the adsorbent is regenerated over a period of time and used again and again.

9. Heat Exchangers:

The various cooling towers of natural draft and forced draft are example of

industrially applied H.Es. These are common facilities in the thermal power

stations and in chemical industries the application of shell & tube heat

exchangers are widely used. this is an excellent application of heat transfer

from one medium to the other.

10.Membrane Separation:

Dialysis is used to separate metals in solution having widely different

molecular weight. for example caustic from sugar solution or cellulose.

11.Size Reduction:

This involves crushing, grinding, pelletizing and prilling. Pelletizing is used

in pharmaceutical industries and prilling used the manufacture of Urea.

Modern chemical processes are offer extremely complex operations involving

100s of pieces of equipment. without a systematic approach it would be


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impossible to analyses an existing process or to design equipment process.

The typical chemical process is analyzed with the following interdependent

considerations like,

- Mass & Energy Balance

- Thermo chemistry

- Unit Operations

- Plant Equipment

- Ancillary Equipment - Process Plant Diagram

- Instrumentation Control

- Economics

which deals with net profit before taxation profit after

taxation dividend paid to the public and share holders. Once the process as

been developed and completed attention can be made to access

the various liabilities, resource and assets.

Alternatives and the remaining choices can be ranked in the order of

desirability. They are as follows;

- Effectiveness for reducing waste - Technical Risk

- Extended of current views in the facility

- Industrial Precedent

- Capital and Operating cost incurred

- Effect of the Quality of the product

- Impact of Plant Operations

- Required time for Implementation

- Other aspects important in the particular situation according to the

industrial

Conservation of Energy:

dE = Q - W This is a steady state batch process.

dH = Q - Ws Thia is for flow process.

Q--> Heat energy transfered across system boundary.

W-->Work energy transfered across system boundary.

Ws->Mechanical work energy transfered across system boundary.

E--> Internal energy of the system.

dE, dH--> Changes in Internal Energy & Enthalpy during the process.

we are already classified the various unit operations and below is a particular

basic column of mass transfer equipment.


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1. Distillation:

It is classified into Batch and Continuous Fractionation.

a. Batch Fractionation:

Used for intermittent operation and handling of small volume of feed

and products.


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b. Continuous Fractionation:

These are used for high volume continous seperation of complex

mistures such as petroleum fractions connected to appropriate

pumps, re-boilers, condensers, scrubbers, strippers and finally automatic

controls.

2. Drying of Solids:

Spray Dryer , Rotary Dryer & Tunnel Dryer are some example of these

types.

3. Evaporation:

Open pan evaporators and multiple effect evaporators as used in sugar and

salt industries for example. Among these halogen family we have technology

to separate chlorine and fluride but production of bromine from the 'sea

brine'is almost not put into practice as the bromine chemicals is highly

corrosive and necessary precaution has to be laid out for practical purpose.

4. Extraction:

Liquid - Liquid Extraction

Solid - Liquid Leaching are examples for this process

5. Fluid Handling Equipments:

Centrifugal pumps

Reciprocating pumps

Jet ejectors

6. Fluid - Solid Contacting:

Fixed Bed

Fluidized Bed

Moving Bed, etc.

7. Fluid - Solid Separation:

Centrifugation

Settling Tank / Sedimentation

Wet Scrubber / Dry Scrubber

Crystallization


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Rotary Filter

Filter Press

Cyclone Separator

Electro-static Preciptator

Bag Filter

Thickeners based on Kynch Theory

8. Fluid Storage:

Gas Holders

Tanks

Pressurized Spheres

Underground Caverns which are used for the purpose of Natural Gas

Storage.

9. Gas - Liquid Contact:

Absorption

Stripping

10.Heat Exchangers:

Fired Heaters

Re-boilers

Condensers

Shell & Tube Heat Exchangers

Jacketed Kettle

Quenching applied in conventional Heat Transfer and Metallurgical

Operations.

11.Membrane Separation:

Dialysis

Gaseous Diffusion

12.Mixing:

Agitation

Solids Blending

13.Size Reduction & Enlargement:

Crushing

Grinding

Pelletizing

14.Solids Handling:

Pneumatic Conveying - Juices transfered to 200 km in Brazil

Bucket Elevators - Coal Industries

Screw Conveyors - Tooth Paste, Turbine Liquids

Belt Conveyors

15.Solid - Solid Separation:

Screening

Elutriation

Froth Rotation


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Jigging

Magnetic Separation

CHEMICAL REACTORS

The Reactor is the heart of the chemical process. The design of an industrial

chemical reactor must satisfy the requirements in four main areas.

Chemical Factors1.

Mass Transfer Factors2.

Heat Transfer Factors3.

Safety Factors4.

1. Chemical Factors:

This involve the kinetics of the reaction weather it's first order or second

order and based on this chemical reaction engineering is built on the design

must provide sufficient residence time to proceed the reaction for the required

degree of reaction and conversion to product.

2. Mass Transfer Factors:

The reaction rate of homogeneous reaction may be controlled by the rate of

diffusion of reactants rather than the chemical kinetics of Langmuir isotherm

and Frendlich isotherm.

3. Heat Transfer Factors:

These describes weather the reaction is exothermic or endothermic. In

Exothermic, heat is released outside and In Endothermic, heat is absorbed by

reactants. The value of heat of reaction is necessary to operate the chemical

reactor.

4. Safety Factors:

This involve the confinement of any hazardous reactant and products as well

as the control of reaction and process conditions.

Based on these factors the Reactor Types as follows;

a. Mode of Operation - Batch or Continuous

b. Phases Types - Homogeneous or Heterogeneous

c. Reactor Geometry - Flow Pattern & Process of contacting the phases.

The five major classes of Reactor;

i. Batch

ii. Stirred

iii.Tubular

iv.Packed Bed (Fixed)

v. Fludised Bed

Compounds like pigments, dye stuffs, pharmaceuticals and polymers are

manufactured by Batch Processes.

The Latest Heat Exchangers are Direct or Contact Exchangers In addition to


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Double Pipe Exchanger, Shell & Tube Exchanger and Plated Frame Exchanger.

Go to www.sdsenthil.com

TOPIC 2: CHLOR ALKALI INDUSTRY, INDUSTRIAL ACID,

CEMENT, GLASS & CERAMICS AND PULP & PAPER

Sodium Chloride

Sodium chloride is the basic raw material for many chemical compounds such

as NaOH, Na2CO3, Na2SO4, HCl, Na2PO4, Sodium Chlorate, Sodium Chlorite

and its source of many other products through its derivatives. Practically all

the chlorine products in the world is manufactured by electrolysis of Sodium

Chloride (NaCl), a common salt is manufactured in three different ways;

Solar evaporation of sea water1.

Mining of rock salt2.From well brines3.

1. From saturated Brine by Multiple Effect Evaporator Process

Brine contains water 73.5%, sodium chloride 26.3%, calcium sulphate

0.12%, calcium chloride 0.003%, magnesium chloride 0.007%.

The flow sheet of process is given below;

Process:

The Brine is first aerated to remove most of the H2S.1.

Addition of chloride will remove H2S by displacement reaction.2.


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Brine is then pumped to settling tank where it is treated with caustic

soda and soda ash to remove calcium, magnesium and ferric ions.

Caustic soda and soda ash are blended in the miser to be taken to

settling tank.

3.

In the Multiple Effect Evaporator (MEE) water is removed and salt

crystals are removed as slurry.

4.

The slurry is sent to washer, where the salt crystals are washed with

fresh brine.

5.

The washed slurry is filtered, mother liquor is return to the evaporatorsand salt crystals from the filter are dried and screened.

6.

Salt thus produced from the typical brine is 99.8% purity or even

greater.

7.

The finest grade (some times made by grinding) is a flour salt, the next

coarsest is table salt and finally the industrial salt.

8.

The Iodine salt has the following composition;

Potassium Iodide (KI) : 0.01%

Stabilizer Na2CO3 : 0.1%

Sodium Thio Sulphate : 0.1%

2. From Saturated Brine by Open Pan Process

Process:

Salt in the form of hopper-like crystal (grainer salt) is made by causing

the salt crystal to form on the surface of brine held in an open pan.

1.

The grainer is a flat open pan 4.5 to 6.0 m width and 45 60 m long

and about 60cm deep. Beneath the pan steam coils system provided for

reciprocating the flakes for salt removal.

2.

The saturated brine mixed with circulating brine from the grinder is

treated to 1200C at which temperature calcium sulphate is soluble and

remove at that temperature.

3.

The precipitated calcium sulphate is removed from gravellier which

consist of bed of stones.

4.

The purified brine is flash cooled to remove the remaining calcium

sulphate.

5.

The slurry is then pumped to the grinders where evaporation takes

place at 960C.

6.

A wet salt crystals obtain from the grinder are centrifuged, dried and7.


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screened.

When the incoming brine has been treated salt of 99.98% sodium

chloride can be obtained.

8.

3. From Rock Salt Mining

About 35% of salt produced comes from mines of 8 different stages which are

operated to produce rock salt. The salt deposits varying color from light

reddish brown to half grey. The purity is 98.5%. After the rock is blasted

loose they are crushed and then screened at the surface level. The remaining

process is the series of grinding, screening to obtain the salft of crystal of

various sizes.

4. From Sea Water by Solar Evaporation

Annual Evaporation exceeds precipitation, the statistics of 125mm of rain

corresponding to 840mm evaporation.

By-products of Normal Salt(also called as value added products)

Manufacture of sodium sulfates from salt and sulfuric acid

2NaCl + H2SO4--->2HCl + Na2SO4

Na2SO4+ 10H2O ->Na2SO4+ 2HCl

Hargreaves-Robinson Process

Sulphur Di-oxide, air, steam are passed over specially prepared porous

common salt. The reaction is as follows;

2NaCl + SO2 + 1/2O2+ H2O --->Na2SO4+ 2HCl

Bleaching Powder

Formulae: (CaOCl2).H2O

Equation: Ca(OH)2+ Cl2--->CaOCl2.H2O

The reaction is a low temperature reaction at 50OC in a counter current action

by passing chorine through a rotating steel cylinder with lifting blades which

slower the solid through the path of the gas. When allow to stand in air the

bleaching powder absorbs CO2 liberating HOCL (Hypochlorous acid). Other

organic acids also liberates same compound. The reactions are,

2CaCl (OCl) + CO2+ H2O --->CaCl2+ CaCO3+ 3HClO

2HClO -->2HCl + O2

After this formation bleaching powder liberates calcium chloride and oxygen.


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When dissolving in water the reaction gives ionized calcium chloride and hypo

chloride. The reaction is,

2CaCl (OCl) --->2Ca2++ 2Cl-+ 2OCl-

The OCl- ion decomposes by liberating oxygen. However the acidity of the

product is determined by the % of chlorine in the compound, which is defined

as weight of chlorine that will exerts the same action as the chlorine

compound what we choose.

In the case of Bleaching powder, average chlorine is the same as the % of

chlorine in the compound. In the case of calcium hypo chloride the % of

chlorine is 47.6% if the chlorine content rises to 99.2% in the compound.

These values are obtained as soon as the freshly prepared compound from the

process is finally taken.

Sulfuric Acid

Lead Chamber Process

Contact Process

Lead Chamber Process

Essentially this process consists of oxidizing a mixture of sulfur dioxide and

water to sulfuric acid using nitric oxide as an oxygen carrier. The reaction is,

H2O + SO2+ NO2---->H2SO4+ NO

This Nitric Oxide (NO) combines with oxygen to from nitrogen dioxide which is

used again in the process. The formation of NO2is given by,

2NO + O2---->2NO2


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The process consists of three stages.

The first stage takes place in the Glover tower. This tower is packed with acid

resistant bricks over which a constant stream of sulfuric acid made by mixing

the output of lead chambers (65% Acid) and the Gay-Lusaac Tower (70%

Acid) combines with oxides of Nitrogen. Then the hot mixture of SO2and Air

from the furnace is fed into the base of Glover Tower and comes into intimate

contact with the descending acid of low concentration. Acid results the gases

from the burners are cooled from 5000

C to about 900

C and the oxides ofnitrogen are extracted from the acid and carried over to the other chambers.

In addition the acid undergoes the concentration of 70% by the time it

reaches the base of the Glover Tower. Some of the spent acid after coming

from the Glover Tower is also sold commercially for processed where that

concentrated acid is required.

The second stage takes place in the lead chamber from which the process

derives its name. Water is spread from the roof on to the mixture of gases are

SO2and NO2. They slowly react together under carefully controlled conditions

of humidity and temperatures producing 65% H2SO4which is collected on the

shop floor. Lead is used in the material of construction as it is not corroded by

acid. The humidity is controlled by the variations in the dry bulb temperatureand wet bulb temperature observed in the psychometric chart available in the

process plant.

The third stage takes place in the Gay-Lusaac Tower which is designed to

recover as much as possible of the Oxides of Nitrogen from the gases leaving

to the chambers after thoroughly washing with cold concentrated acid.

The main purpose of this Tower is to minimize the problem of escape of NO2to atmosphere. But in the later stages the recovery was more important as

the efficiency was high and cost very cheap. A small loss of oxide of nitrogen

is inevitable. However it is made good by introducing additional nitric oxide

formed by catalytic oxidation of ammonia.

This chamber process produces cheap acid of doubtful purity with

concentration of 65-80% at maximum. This was used for manufacture of

fertilizers, but where more concentrated acids are required the contact

process is followed.

Contact Process


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Today contact process is the most widely used process for the manufacture of

H2SO4throughout the world. The raw materials used to make sulfuric acid are

elemental sulfur, H2SO4and H2S.

Till 1970, Ion Pyrites and related compounds were the predominant raw

materials. The large amount of sulfuric acid also produced as a by-product of

non-ferrous metal smelting. i.e. roasting sulfide ores of copper, lead,

molybdenum, nickel, zinc and some others. The process is dividing to the

following steps;

Generation of sulfur dioxide gas1.

Catalytic Oxidation of SO2to SO32.

Absorbing SO3to form H2SO43.

The reactions are as follows;

S + O2 --->SO21.

SO2+ O2 --->SO3 ^H = -98KJ2.

SO3+ H2O --->H2SO4 ^H = -132.5KJ (Highly Exothermic

Reactions)

3.

Properties of Sulfuric Acid

When a dilute solution of sulfuric acid is distilled a constant boiling pointmixture is obtained contains 98.3% of H2SO4. This mixture boils at 338

0C

and has a density of 1.84gm.cm-3is the normal concentration acid available in

the laboratory. If the little SO3is dissolved in that acid 100% takes acid is

obtained and an oily liquid which freezes to crystals of white color at 10 0C.

Concentrated sulfuric acid is highly corrosive and should always be handle

with care. It causes severe bores when contacted with the skin.

Reactions of Sulfuric Acid


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It is a strong di basic acid reacting to bases to give a series of salts, like

sulphates and bisulphates. It is represented by,

H2SO4H++ HSO4-2H++ SO4 2-

The dilute acid reacts with many metals forming sulphates and hydrogen. But

it does not react with lead, copper, mercury and silver. Iron reacts to give,

Fe + H2SO4 ---->FeSO4+ H2^

When the acid highly concentrated attacks any metals forming sulphates and

therefore silicon steel is used for construction of distillation column where

sulfuric acid is involved. Gold or Platinum have no reaction with H2SO4whereas copper forms copper sulfate with H2SO4liberating SO2.

Uses

Manufacture of Phosphate, Ammonium Sulphate and production of these

fertilizers consume about 40% of total sulfuric acid manufacture. Other large

scale users are manufacture of pigments, light barium sulfate, titaniumdioxides and manufacture of viscose rayon for artificial silk, detergents,

dye-stuffs, drugs, explosives, plastics, for dissolving unsaturated hydrocarbon

during refining of petroleum, for pickling for iron steel (removing oxide layer

before galvanizing) tinning, plating & painting and finally for killing weeds for

the agricultural production.

Cement

Definition

The term Cement refers to many different kinds of substances that are usedas binders or adhesives. It refers to inorganic hydraulic cements (mostly

called as Portland cement) which are hydration form relatively insoluble water

bonded aggregation of high strength and dimensional stability. In the last

century it has been found that iron in combination with cement has proved

substantially the useful concrete for very high-rise buildings and massive

constructions. Hydraulic cements also manufactured by processing and

proportionate raw materials burning (clinkering) at a particular temperature

and grinding the resultant product to obtain the cement.

The cement consist mainly tri-calcium silicate and di-calcium silicates. The

raw material are lime stone rich in calcium and silica such as clay or shale.

Clinker Formation

Portland cements are manufactured from raw mixes including components

such as calcium carbonate, clay or shale and sand. When the temperature of

materials increases during the passage in the rotary kiln the following

reactions occur;

Evaporation of free water1.

Release of combined water from the clay2.

Decomposition of magnesium carbonate3.

Decomposition of calcium carbonate4.


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Combination of lime and clay oxides5.

Finally cooling is done to maintain the phase equilibrium.

Manufacturing Processes

Wet process and Dry process plants produced Portland cement. It consist of

quarrying and crushing the rock, including control of the clinker composition

by systematic core drillings and selective quarrying.

The next process is grinding the proportioned materials to high fineness. Ball

Mills are used for the both the process to grind the material although roll

crushers are used for dry process.

The high temperature of operation vaporizes the alkalies, sulphur and halides

(rotary kilns for Wet process, Dry process , suspension free heaters or

precalciners). The grinding is done by open circuit grinding or closed circuit

grinding depending on the fine powder of cement required.

Manufacturing procedures (Wet & Dry processes)

The Wet Process is the original one is being displaced by Dry Process for few

factories because of saving energy, accurate control and proper mixing of theraw material. The dry process plants account for 58% of the total amount

manufactured with full production capacity. It is illustrated in the following

flow chart.


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In the wet process the solid materials after dry crushing is reduced to fine

powder in wet tube or ball mills and passes as slurry through bowl classifiers

or screens. The slurry is pumped to connecting tanks where rotating arms

takes the mixture homogeneous and allow the final adjustment in

composition. For this purpose some of the cement plant the slurry is filtered

in a continuous rotary filter and fed into the kiln.

The dry process is especially applicable to natural amount rock and to

mixtures of limestone, clay, shaves as slate. In this process the materials are

crushed roughly are passed through gyratory or hammer mills, dried, sized,

finally grounded followed by air separation or the pneumatic process.

Before entering the rotary kiln thorough mixing and blending takes place. The

rotary kiln where the powder material is fed the chemical reactions takes

place. Heat is provided by burning of oil, gas or pulverized coal using

preheated air obtained from cooling of the clinker from the high temperature

to lower temperature. And the length of the rotary kiln is increased the

thermal efficiency very high. Due to this process of heat transfer vaporization

efficiency also increases because of evaporation of moisture and water in the

mix. Normally the vaporization efficiency is twice the thermal efficiency forthe process of conduction into material.

Dry process kilns are 150 ft long but the wet process over 500 ft kilns is quite

common. The internal diameter is around 20 ft. The RPM is to 2 depends on

the size. The kilns are inclined so that materials fed at the upper end travel

slowly to the lower firing end (by blower) and taking 3 hours to reach he

bottom end.

To improve the economy of kiln heat water is removed from the wet slurry

before charging into kiln. Some of the equipments are employed slurry filters

and Dorr Thickeners. Efficient air pollution control equipment such as bag

houses or electrostatic precipitators are required for the process. Waste heat

boilers are sometimes used to conserve heat and particularly economical for

dry process cement. A refractory lining is given inside wall to protect the heat

form escaping outside and maintain a temperature of 800 OC. In the recent

days computers are used to improve kiln control. The sketch of rotary kiln is

given below;


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The final product form consists of hard granular masses of of the inch in

size called clinker. It is discharged form the rotating kiln into air-quenching

coolers which brings the temperature to 100 0C. The cooling also preheat the

combustion air pulverizing followed by grinding in the tube or ball mills and

automatic packaging complete the process.

There are many types of compounds in cements according to the composition

numbering 102 types of cements according to the applications. Special

cements also manufactured for corrosive conditions and the various types of

sulphur cements, silicate cements, adhesive cements to have a few. The

industrial importance sulphur cement are resistant to solves acids, alkalis, oil,

grease or other solvents. These are employed for the joining of Tiles and Cast

Iron Pipes. Silicate cements with stand a temperature of 1000 0F.

Glass & Ceramics

Glass

Glass was formed naturally from common elements in the earth dust long

before anyone ever thought of experimentally with this composition, moulding

its shape of putting it to the myriad of used that it enjoys the world today.

Glass technology evolved around 6000 years back and sum of the todays

principles followed the old times. This includes what is today known about the

structure of glass, its composition, properties, method of manufacture and

uses.

The term glass follows the definition of MOREY, GLASS is an inorganic

substance in a condition that is continuous and analogous to the liquid state

of the substance. But which as a result of a reversible change in viscosity

during cooling, has obtain so high a degree of viscosity has to be for allpractical rigid.


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Most glass particles are manufactured by a process in which raw material are

converted at high temperature to a homogenous melt that is then formed into

various articles or glass wares employed in laboratories.

The above flow diagram summarizes the details of conventional glass

manufacturing. The vapor deposition of SiO2 from a flame fed with silicon

chloride (SiCl4) and oxygen is basis for manufacturing high purity glass usedfor blanks that are redrawn into optical-wave guide fibers. Fused silica items

that cannot be formed from viscous melts of SiO2or Quartz are prepared by

vapor deposition. Raw materials are selected according to purity, supply,

pollution, potential, ease of melting and cost.

Sand is the most common ingredient. Limestone is the source of calcium and

magnesium. The reducing agent is powdered anthracite and common

colorness for glass includes Iron, chromium, cerium, cobalt and nickel.

Melting and fining depend on the batch materials interactive with each other


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at proper time and on the proper order. Thus the stream must be taken to

obtain materials of optimum grain size, to weigh them carefully and mix

intimately. The efficiency of the melting operation and the uniformity and

quality of the glass product are determined in the mixing house.

Batch handling systems are widely used in the industry from manual to fully

automatic small furnaces for annual production to large continuous tank for

rapid machine forming. The two important equipments are screw feeder and

reciprocating pusher. Control devices have advanced computer assistantoperations. Radiation pyrometer with thermocouples monitor furnacetemperature. Natural gas, oil, electricity are the primary source of energy andpropane is used as a backup reserve for emergency. Molten glass is molded,drawn, rolled and quenched depending on the desired shape and use. Bottles,

dishes, optical lenses, helix picture tubes are formed by blowing, pressing,

casting and filling the glass against mould and cool it to get the desired shape.

Art glass is made manually and an glass called FRIT is obtained by powdered

glass and quench between water cooled rollers, poured into water and then

dried. Glass optical formed as high temperature must be cooled in order to

reduce its strain and associated stress caused by temperature gradient.

The following are the types of glasses;

Flint Glass1.

Bottle Glass2.

Pyrex Glass3.

Photosensitive Glass4.

Froast Glass5.

Ground Glass6.

Insulating Glass7.

Vitreosil Glass (99.9% Silica)8.

Fused Silica Glass9.

Optical Glass10.

Lead Glass11. Colored Glass12.

Opal Glass13.

Fiber Glass14.

Safety Glass and15.

Glass Wool16.

Ceramics

White Waxes

White wax is a generic term for ceramic products which are usually white andof fine texture. These are based on selective grades of clay bonded together

with varying mount of fluxes and heated to a moderately high temperature in

kiln of 1200-1500 0C. Because of the different amounts and kinds of waxes

there is a variation in the degree of vitrification. Among white wax, from

earthenware to vitrified china the degree of vitrification is the progressive

reduction in porosity provides the basis for the useful classification of ceramic

products as follows;

Earthen ware some times called as semi vitreous thinner ware is

porous, non translucent with a soft glaze.

1.


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China ware a vitrified translucent ware with a medium glaze which

resist abrasion to degree which is used for non-technical purposes.

2.

Porcelain a vitrified translucent ware with a hot glaze which resist

abrasion at maximum degree. It includes chemical, insulating and

dental porcelain.

3.

Stone ware one of the oldest ceramic products developed and

rewarded as throughout porcelain.

4.

Sanitary ware formed from clay is porous and preferred for vitreous

application with a tri-axial composition.

5.

White ware white ware tiles available in number of times, classified

as floor tiles, resistant to abrasion and impervious to stain penetration

and used as wall tiles of a variety of colors and is formed small surface.

6.

To represent a typical manufacturing procedure in the ceramic group,

porcelain is chosen below. There are three lines of production.

Wet process porcelain used for production of fine grained, highly glazed

insulators for high voltage application and cast porcelain necessary for making

pieces to large are too intricate for the other two methods.

The 3 processes are based on the same raw materials. The difference in

manufacture is the drying and forming steps.

Description of Process

Raw material of proper proportions and properties to furnish porcelain of the

desired quality are weighed from overhead into the weighing car. Feldspar

clays and flint are mixed with water in the blender (clay-water mixture) and

then passed over a magnetic separator, screen and store. Most of the water is

removed by filtration. All the air is removed by the mill with the help of

vacuum operation. This produces stronger or hard porcelain. The prepared


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clay is formed into blanks and hot pressed suitably. They are then dried,

trimmed and finally completely dried all under carefully controlled conditions.

The hydro separator removes the water and moisture containing impurities.

The vitrification is carried out in tunnel kilns at a particular temperature and

then porcelain articles are protected by Saggers fitted in the final stage of the

process. The glazing and firing are simultaneously done to obtain lustre or

shiny nature of the porcelain. They are immediately tested for electrical

insulation after storage for sale.

The table-ware is manufactured by more complicated procedure then

illustrated by the porcelain process. Some objects are obtained by the

porcelain process. Some objects are obtained by the potters wheel in the

conventional cottage industry employed in rural areas. For separate

application, complex shapes for chemical laboratories are manufactured by

different mould for the required applications.

Glazing is an important process in the manufacture of white wax. Some times

a glaze is a thin coating of glass melted on the porcelain surface for porous

application. The chemicals used are soda ash, potash, fluorspar, borax for this

type of special application. The temperatures for glazing is around 1050-15000C.

Refractory and colorants for ceramics

It is broadly divided into two groups; one for clay based products like tiles,

sanitary wares and thinner ware and the other based on silica as a major

ingredient. In the manufacture of glasses continuous for laboratory conditions

at normal temperature and pressure color is obtained by a suspension of the

coloring medium when final stages of the product obtained.

Pulp and Paper Industry

The transmission of thought my means symbols was practiced thousands of

years back, prior to Christian era. Primitive people used to stores clay, palm

leaves, shells and bark of plants are which to inscribe information. Egypt is

the country where origin of paper took place, now there is no production in

that country of paper. On the other hand in china about 200 B.C. the paper

was manufactured and now the forerunner of the industry.

Raw Materials

The raw materials employed in the pulp and paper industry are woods, rags,

straws, bagasse, sulfur, limestone, alum, soda ash and clay. The only country

to have all the above raw material within the country is USA.

1. Wood

It is the outstanding source of cellulose in fact more than 90% of the paper

consumed in the world is made from wood fiber. Again U.S. has the

abundances of wood excepting Russia. The North American continent

processes 40% of soft wood.

2. Fibrous Raw Materials

Since 1800 where wood was first employed intensively for the manufacture


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of pulp no other alternative has append so for. For this purpose the reuse of

waste paper become dominant and contributes 1/3of total production.

3. Non-Fibrous Raw Materials

The important material here is sulfur about 200,000 tones of sulfur has

produced for paper production. The other materials caustic soda, soda ash,

rosins and bleaching components, lime is employed for sulfite cooking process.

The mineral substances such as clay, talk, chalk, barites, zinc compounds and

titanium compounds are used for manufacture of paper as non-fibrous

materials.

Manufacture of Pulp

Wood Pulp: The process is employed in the preparation of pulp from

wood are mechanical (ground wood) and chemical (sulfite, sulfate &

soda) and a combination of mechanical and chemical known as

semi-chemical. The object of the formation of pulp is to separate the

wood into fibers. The original wood contains 50% of non-fibrous

material like lignin and inorganic matter.

1.

Mechanical Pulp: This mechanical or ground wood process is used

largely on coniferous wood (having the name from coniferous forest

past). Especially with low rosin content such as spruce, balsam and

hemlock, jack pine is used to produce pitchy hard wood. This mechanical

pulp used for newsprint, wallpaper, wallboards and paper boards. It is

sometimes mixed with chemical pulp.

2.

Chemical Pulp: It is a material which made after treating the wood

by chemical which remove the cementing material, for this pulp the

wood is cleaned thoroughly from bark & knots. The logs of woods are

conveyed to the chipper where they are forced at an acute angle against

a disc on the surface above which heavy knives are operated on. The

chipping operation produces pieces of wood of various sizes and then

classified as saw dust.

3.

Sulfite Process:

H2O + SO2-----> H2SO3

Ca(OH)2+ 2H2SO3-----> Ca(HSO3) + 2H2O

CaCO3+ 2H2SO3----> Ca(HSO3)2+ H2O + CO2

Sulfur is melted and then burned into Sulfur Di-oxide (SO2) in special rotary

burners where the supply of air is regulated to prevent the formation of

objectionable SO2. The gas is cooled in water immersed pipes after which it is

absorbed by;

Large absorbers containing milk of lime1.

Through tall towers made of concrete packed with limestone over which

water trickles down.

2.

The sulfite pulp is used for wide application in newsprints, boards, wrapping

papers and certain grades of printing papers where reasonably light color and

good strength are required.

Bleach sulfite paper is used in writing, typing paper, tissues, grease proof

papers and high grades of wrapping paper.


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Sulfate Process:

It derives the name from fact that loss of alkali and sulfur is compensated by

sodium sulfate (salt cake) or its equivalent. The term KRAFT means strong

and applied to pulp prepared by this process for producing the strong pulp.

The raw materials used are southern pine, spruce, jack pine, and tamarack.

This is followed by cooking the chips and then washing followed by recovery of

sulfate liquor. The main reaction is;

Na2SO4+ 4C --->Na2S + 4CO

Analysis of solids in sulfate process;

Solids Original smelt

(%)

Green liquor

(%)

White liquor

(%)

Na2CO3 61 64 11

Na2SO4 4 5 6

Na2S 27 31 22

NaOH - - 61

Silica 2 - -

Insoluble 6 - -

Apart from the above processes there are miscellaneous processes like soda

process, semi chemical pulp process and rag pulp process.

Grades of Paper

There are number of method by which paper may be classified;

By the type of furnish process in the paper manufacture. Eg. Sulfite

process

1.

By the property. Eg. Grease proof paper, absorbent paper.2.

By the use to which its applied. Eg. Newsprint paper.3.

Tissue: It is the lightest weight paper. Generally grade on a

Yankee machine like napkins, light weight wrappings and toilet papers.

Wrapping: Bags, envelopes and bread wrappers

Writing: Stationary, ledger, document and type writing sheets

belongs to this category

Printing: Newsprint, catalogue and bible papers

Books: Books & Magazines

Building: Papers mixed with asbestos employed in construction

work, sheathing papers, felting papers, dead ending felts for acoustic

properties involves and floors the auditorium.


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Boards: By far the largest production of the industry falls in this

class. The subdivisions are numerous like containers, binders, bottle

caps, chips and wall boards.

Research

The application of science and engineering in pulp and paper manufacture are

brought about to improve operation and progress in the manufacture for

better products and also the reduction in prices.

Consumption

Paper products and the related chemical are important to a developing nation

such as India, the per capita consumption of paper is the measure of the

educational, social, cultural and industrial activities of the country as given

below;

Country Consumption (Kg/Person/Year)

USA 206

UK 167

Japan 57

USSR 16

India 1.5

The end use distribution of paper is given below;

End Use Distribution (%)

Paper & Paper Head 65

Newsprint 20

Rayon (Chemical pulp) 15

Go to www.sdsenthil.com

TOPIC 3: OIL, SOAP & DETERGENT, PETROLEUM REFINING,PETROCHEMICALS AND SUGAR


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Hydrogenation of Oils

Large amount of groundnut oil, cotton seed oil, etc are hydrogenated in

presence of suitable catalyst to obtain solid edible fat called vegetable ghee.

The purpose of hydrogenation is to increase the melting point of oil and

convert in to an edible fat. In other words, hydrogenation are hardening of oil

is a process in which various unsaturated radicals are converted into

completely saturated Glycerides. There fore the hydrogen plays an important

role in the process with a catalyst. The process is carried out by keeping the

oil at a temperature of 140-180 0C containing finely divided liquor in

suspension by the subsequent absorption of Hydrogen.

Optimum conditions for the Process

The Hydrogen needed can be manufactured by a number of methods but

hydro carbon steam process has been widely used. The hydrogen must

be very pure. Traces of gaseous sulfur compound, H2S, SO2, Arsenic and

Chlorine compounds are strong catalyst poisons. These have to be

removed before the hydrogenation process.

1.

The oil must be pure as well as free from fatty acids. Fatty acids reactwith Nickel and its oxides to form Nickel Soap which is soluble in oil. For

purification, the oil is taken in a tank fitted with steam coil are heated

to 30 0C. Then caustic soda is added and mixture is agitated for about

20 minutes by compressed air. The moisture is removed by heating the

oil in vacuum. The moisture may be hydrolyses the oil at high

temperature and pressure to form fatty acid.

2.

In order to prevent the Pyrophoric Nickel from catching fire the Nickel

catalyst is carefully transferred to the oil out of the contact with air.

3.

In order to keep the Nickel particles in free suspension and to bring the

oil in close contact with Hydrogen, the mixture of oil catalyst and

Hydrogen is agitated.

4.

The catalyst is Nickel Oxide or Nickel Formate which is reduced to metalby Hydrogen gas are forms Raney Nickel. The charge is kept at

maximum temperature for about one hour and then cooled. During the

cooling period the Hydrogen is passed to create the product

hydrogenated oil stored in the end of the process.

5.


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Recent research has shown that Palladium has been found to be more

effective then Nickel. i.e. 1 part in 1,000,000 parts of oil is sufficient. And the

reaction takes place at lower temperature and takes less time. The only

disadvantage is Palladium is costlier than Nickel, Raney Nickel and other

catalyst.

The process of Hydrogenation is exothermic reaction. There fore it is favored

by low temperature. The optimum temperature is around 150 0C.

Apart from the above there are two processes of Hydrogenation of oil

1. Dry Process

2. Wet Process

1. Dry Process

The refined oil from the storage tank is brought into a vacuum evaporator

where it is heated at about 50 0C at low pressure in order to expel air

moisture. By means of the pump the oil is charged into convertor by pipe

provided at the bottom of the evaporator. The convertor is a cylindrical

pressure vessel provided with Hydrogen distributor. In the bottom steam coils

for heating and circulating the oil. The Hydrogen gas is sent at a pressure of

5.6 atm. into the convertor. The steam is turned off to accelerate exothermic

reaction and convert the oil into a hydrogenated substance for further

purification process.

For the commercial value Bleaching is done for aesthetic consideration for the

market value.

2. Wet Process

In wet process Nickel salt is reduced into finely divided Nickel in the oil before

hydrogenation in a continuous process. There are two wet process are

employed, in one process Nickel Formate is used and the reduction is carried

out at 190 0C with Hydrogen.


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faster, increases the cleaning property of the soap and softens the hard soaps.

Rosin requirement is about 50% and the grease is 23%.

3. Caustic Soda: It is available in the form of flakes, blocks and sticks as

well as in solution of sodium hydroxide in various concentrations. The caustic

product potash is involved in the manufacture of saving creams.

4. Sodium Chloride:Sodium Chloride is used for salting out about 12.5 parts

per 100 parts of oil to be saponify is used.

5. Binding Materials: Sodium Silicate, Soda Ash, Tri Sodium

Phosphate, Borax are used as Binding materials. They improve the soap

texture and prevent the formation of precipitate in hard water.

6. Fillers: The weight of the Soap is determined by fillers such as talc,

starch, glauber salt, pearl ash, etc without affecting the detergency of the

washing soaps.

7. Colouring Matter: Organic dyes and inorganic pigments are used.

As a Dye the material should be inert to alkali used in making soap and

should not separate when soap is blended in the process. Common coloring

matters are methyl violet, Bismarck brown, safframine for red, zinc oxide forwhite color, chrome green for green color, cadmium for yellow color, ultra

marine for blue color, eosin for pink color, vermilon for rose shade.

Intermediate colors are obtained by blending the above colors.

8. Perfumes & Perfume Fixatives: These impart fragrance for the

soap. They may be natural or synthetic. Examples are sandalwood oil, lemon

grass oil, clove oil, eucalyptus oil, lavender oil and cinnamon oil, etc. The

synthetic perfumes are,

Jasmine (Benzyl Acetate)

Rose (Phenyl Ethyl Alcohol)

Lylac (Terpenol)

Musk (Benzoate)

Manufacture of Soap

Soap is either made by hot process or cold process. Usually laundry soaps and

bath soaps are manufactured by hot process. Transparent and other special

types of soaps are produced by cold process. In most of the cases soap

obtained by hot process settled and separated from Glycerol solution.

Subsequently Glycerol is separated out as a by-product. The hot process is

divided into tow types,

Batch Process1.Continuous Process2.

The Batch Process is carried out in a soap kettle made of steel plates and

having large diameter. The kettle is supplied with steam with a mixture of

melted fats, grease, oil in a proper amount for the mixture. The amount of

caustic soda is regulated to undergo the hydrolysis reaction. The boiling is

continued until the saponification is completes. A pasting mass is formed by

conversion of Tri-stearin to Di-stearin. The final product contains soaps, water,

glycerol, unused alkalis, sodium chloride, sodium carbonate, sodium sulfate as

impurities. After this saponification is complete and the steam is cut off with


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the separation of salt on the surface for the batch process to stop and deliver

the soap product.

In the Continuous Process the raw materials oils and fats and the catalystusually zinc oxide are blended and fed into a hydrolyser or splitting tower

fitted with steam coils through which steam is passed for heating the charge.

The splitting of fat takes place continuously in a counter current manner and

about 250 0C and 40 atm pressure. The fat raises again the aqueous phase

which also dissolves glycerol in reaction. The fatty acids are discharged from

the hydrolyser to a flash tank called decanter where excess of water is

separated. They fatty acids are the passed to a heat exchanger and then to a

vacuum still and distilled. The distillate is collected as overhead and bottoms

are stored for recovery. Then the distillate neutralized by caustic soda in a

continuous neutralizer. As the result of this soap is obtained which is with

drawn hot into a agitator tank. This soap contains Water, NaOH and NaCl. This

is dried in a high pressure steam exchanger by heat and pressure, finallycollected in a flash tank. The pasty mass is missed with air and cooled to 650C. Here the soap is continuously extracted and collected into soap frames

where it solidifies on cooling. Then it is cut into bars as usual. The particular

process delivers the product in a day whereas the batch process operates for

few more days.

Petroleum Refining


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Cracking

Cracking is the process by virtue of which crude petroleum of their fractions

are decomposed by heat to produce products which have lower boiling points.

The main object of cracking is mainly the production of gasoline. The two

types of cracking are,

Thermal Cracking1.

Catalytic Cracking2.

1. Thermal Cracking

The main reaction is C10H22--Cracking-->C6H12+ C6H10

Paraffin+Olefin

The crude petroleum is heated to 1000 0F in a pipe heater. A pressure of 1000

psi is maintained and the lower molecules are further decomposed as below;

CH4---Decompose-->C + 2H2

Gas and Gasoline in vapor form go out as two products. The vapor phase iscondensed to obtain Diesel, Petrol and then LPG in the bottling plant to serve

energy requirements. The coke deposited in the process is removed

periodically and the process which is a continuous one is sustaining for the

various fractionation products. The various other forms of thermal cracking

are as follows;

i. Viscosity Breaking

ii. Vapor Pressure Cracking

iii. Thermal Reforming

i. Viscosity Breaking: Here various oils and residues obtained after

thermal cracking are to produce various oils of different viscosity. This is

called as Viscosity Breaking. The temperature is 460 0C and pressure is 500psi.

ii. Vapor Pressure Cracking: Here Cracking is done in such a way there

is only vapor phase obtained after cracking. By doing so aromatic hydrocarbon

and gaseous products are obtained.

iii. Thermal Reforming: Here heavy gasoline of lower octane number is

cracked to get higher gasoline of higher octane number. The temperature is

530 0C and pressure is 750 psi. The flow sheet of Thermal Reforming is given

below;


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2. Catalytic Cracking

Gasoline produced by Thermal Cracking has octane number 72. If the octane

number is increased the yield decreases which can be rectified by use of

catalyst to increase the rate of decomposition of the hydrocarbons in the

crude petroleum. Hence gasoline produced by catalytic cracking is low in

oliefic and high in paraffinic and aromatic hydrocarbon. The advantages of

catalytic cracking are,

No fuel from outside is required for catalytic cracking1.

All the heat required is obtained by heating the coke deposition the

catalyst

2.

The pressure is low3.

The Gasoline has a high octane number4.Total yield of Gasoline is high5.

A sulfur content of all the products is low as it is eliminated as H2S.6.

Types of Catalytic Cracking

The two types of Catalytic Cracking are,

Fixed Bed Catalytic Cracking1.

Moving Bed Catalytic Cracking2.

The first one is a catalytic cracking where fixed bed of catalyst is used. The

catalyst in a form of granules or pellets and bed of the catalyst for fixed in the

catalyst covers. Oil vapors which are heated to the cracking temperaturethrough the catalyst are carbonized at which it is reactivated by burning the

carbon. Oil vapors are diverted tot eh second catalyst chamber.

Second one is a catalytic cracking where moving bedof catalyst is used. The

catalyst in the form of fine powder flows down through a hopper into a reactor

where cracking takes place. The carbonized particles of the catalyst come

down against a raising current of air to remove the carbon deposit of the

catalyst as it is burnt off.


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1. Fixed Bed Catalytic Cracking Process

The fixed bed catalytic cracking method is described in the following diagram.

The charge is passed through a heater where it is heated to cracking level

then it is goes to catalyst towers. These towers have catalyst tubes and

around these tubes molten salt mixtures (mixture of sodium nitrate and

sodium nitrite) are circulated to distribute heat and maintain uniform

temperature in the reactor. The cracked vapors form these catalyst towers of

fractionators in the fractionating column to recover gases and gasoline vapors

from the top and the heavy gas/oil is removed from the bottom of the column.

Gasoline vapors are cooled and condensed in the condenser and then sent to

the stabilizer. In the stabilizer certain dissolved gases are removed and the

desired boiling range and vapor pressure is obtained. The main catalysts used

are

Bauxite pellets1.

Silicon Nitrite complex of Alumina (SiN2.Al2O3) of 6 mesh size2.

2. Moving Bed Catalytic Cracking Process

The moving bed catalytic cracking method is described in the following

diagram.


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series of the formula CnH2n-6Eg. BTX

Asphaltscontain atoms of carbon, hydrogen, sulfur, oxygen and

nitrogen. Various resins are used as adhesives which are semi solids in

structure.

3.

The crude is classified into paraffinic base for aliphatic compounds, naphthenic

base for cyclic compounds and an intermediate base for both of the above.

The petroleum refinery products are classified as;

Gas Fraction Eg. Natural Gas, whose main composition is methane

and the second one is LPG

1.

Light Distillates Eg. Petroleum & Kersosene2.

Intermediate Distillates Eg. Diesel3.

Heavy Distillates Eg. Wax & Lubricating Oil4.

Residue Eg. Grease & Asphalt5.

The normal refinery processes for the manufacture of various products are

done by physical changes like distillation, absorption, extraction, adsorption,

crystallization, heat transfer and fluid flow to name a few. Similarly the unitprocesses involving chemical changes are pyrolysis, reforming,

polymerization, alkylation, isomerisation, sulfur removal, hydrogenation, etc.

Lighter most products ----> Methane ---->Methanol, Chloromethane

Naphtha ---Steam/Cracking---> Ethylene ---->Ethyl Oxide, Acetaldehyde

Propylene --->Iso-propanol, Cumene,

Polypropylene

C4, C5Series -----------> Butane -----> Butadiene

Hydrocarbons --Reforming--> Benzene ----> Ethyl Benzene, Maleic

Anhydride

Toluene ----->Nitro Toluene, Phenol

Xylene ------>Phthalic Anhydride,

Terephthalic Acid

Manufacture of Chloromethane

Methane on chlorination yields successfully the chloromethane by substitution

of hydrogen atoms by chlorine. The flow sheet of the industrial manufacture isgiven below;


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Reactions

CH4+Cl2 --> CH3Cl+HCl -Cl2--> CH2Cl2+HCl -

Cl2--> CHCl3+HCl ---Cl2-->

CCl4+HCl

Methane Methyl Chloride Methylene Chloride Chloroform CTC

These compounds of the chlorination reaction are used as industrial solvents

and intermediates in the manufacture of organic compounds for dye and

dyestuffs manufacturing plants. Similarly we have production of ethylene

oxide in a fluidized bed reactor to produce the product and used for

manufacture of ethylene glycol. The reaction is exothermic and the heat

generated may be used for other purposes like heat exchangers of the type of

shell & tube, etc. Acetaldehyde manufactured from ethylene by exothermic

reaction with palladium chloride catalyst in a series of strippers and

distillation columns for the manufacture. Isopropyl alcohol is manufactured

from propylene by reaction with industrial acids to form the product. Cumene

is another petrochemical manufactured from benzene by packed bed staged

reactor at a temperature of 250 OC in the presence of phosphoric acid.Butadiene is another compound obtained from C4H10 to produce finally

styrene and rubber for the polymer industry. Phthalic anhydride and maleic

anhydride are produced from tubular reactor by the production of isomers and

dehydration reaction to form compound polyesters. Phenol is a very important

compound obtaine

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