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LECTURE–3: UNIT PROCESSES & OPERATIONS PROCESS DIAGRAMS

CHEMICAL TECHNOLOGY (CH-206)

Dr. Vimal KumarDepartment of Chemical Engineering

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UNIT PROCESSES AND INDUSTRY Alkylation (Petroleum, Organic chemicals) Amination by ammonolysis (Dye stuffs, Organic Chemicals, Synthetic

fibers) Amination by reduction (Dye stuffs, Organic Chemicals) Ammonooxidation (Plastics, Synthetic fibers) Calcination (Cement) Cabonylation (Organic Chemicals) Caboxylation (Organic Chemicals) Combustion (Process Heating) Condensation (Synthetic perfumes) Cracking or Pyrolysis (Petroleum, Destruction distillation of coals) Cynadation or Cynation (Organic Chemicals) Cyclaization (Petroleum) Dehydration (Organic and inorganic chemicals) Dehydrogenation (Synthetic rubber) Deazotization and Coupling (Dyestuffs) Disproportionationa (Organic Chemicals) Double decomposition (metathesis) (Inorganic Chemcials)

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UNIT PROCESSES AND INDUSTRY Esterification (Oils and Fats, Soaps, Organic chemicals) Halogenation (Organic Chemicals) Hydration (Organic and inorganic chemicals) Hydroformylation (Organic Chemicals) Hydrogenation (Fats and Waxes, Coal hydrogenation, Petroleum) Hydrolysis (Organic Chemicals) Hydroxilation (Detergents) Isomerization (Petroleum) Nitration (Explosives, Dye stuffs, Organic Chemicals) Oligomerization (Organic Chemicals) Oxidation (Organic Chemicals) Polymerization: addition and condensation (Petroleum, Plastics,

Elastomers, Synthetic fibers) Reduction (Polymers, Catalysts) Sulfonation (Dye stuufs, surface active agents) Thionation (Organic Chemicals)

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UNIT PROCESSES AND INDUSTRY Calcination (Cement)

Cabonylation (Organic Chemicals)

Combustion (Process heating)

Cracking or Pyrolysis (Petroleum)

lime limestone

COCaOheatCaCO 23

Monoxide

acid Acetic Carbon Methanol

COOHCH CO OHCH 33

ter WaOxygent Methane

O2H 2O CH 224

C-C-CC C-C-C C-C-C-C-C-C-C

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UNIT OPERATIONS/PROCESSESCategory Unit

operations/processes Functional role

Fluid operations

a) Centrifugal pump b) Reciprocating pump c) Compressor d) Expander

a) To pressurize liquids and gases. b) To depressurize gases

Solid operations

a) Crusher b) Grinder a) To reduce the size of solids

Solid-fluid separators

a) Cyclone separator b) Centrifuge c) Electrostatic precipitator d) Classifier & Thickener e) Liquid-liquid separator

a) To separate solid particles from solid-liquid/gas mixtures

Heat exchangers

a) Shell & Tube heat exchangers b) Fired heaters and furnaces c) Coolers

a) To remove/add heat to process streams so as to meet desired conditions in other units.b) Either utilities or pre– heating/cooling of other process streams.

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UNIT OPERATIONS/PROCESSESCategory Unit operations/processes Functional role

Mass transfer units

a) Phase separation b) Distillation c) Absorption d) Stripping e) Adsorption f) Extraction g) Leaching h) Crystallization i) Membrane

a) To separate a feed into products with different compositions. b) A third agent (heat or compound) is usually used to carry out separation.

Reactor units

a) Continuous stirred tank reactor (CSTR) b) Plug flow reactor (PFR) c) Packed bed reactors (PBR) d) Slurry & Trickle bed reactors

a) To carry out reactions in homogenous fluids (gases/liquids). b) To carry out catalytic and multi-phase reactions.

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PROCESS DESIGN

Type of flow sheets Block diagram Simplified engineering flow sheets (stream

quantities, specifications, material and energy balance instrumentations details, process auxiliary requirements)

Other design flow sheets (piping, electrical and plant layouts)

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PROCESS DESIGN

Process steps Reactant preparation Reaction Separation of products Purification of products

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PROCESS DESIGN

Design steps Collection of all laboratory and process development

information Flow sheet preparation Selection of conventional design procedure for

equipments designated on the flow sheet for a particular unit operation

Reactor design (optimum) Selection of control instrumentation for process

monitoring and analysis Selection of size materials handling equipments –

pumps, piping, conveyors, etc. Design of all process auxiliaries Plant layout Itemizing of all designs for cost estimation

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THANKS

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UNIT OPERATIONS/PROCESSESREACTOR UNITS

Unit operations/processes Functional role

Continuous Stirred Tank Reactor (CSTR)

- Well mixed reaction system set alignment - Homogenous liquid/gas phase reaction - Most easy configuration - Temperature control through Jacket - Reactant instantaneously reaches lowest concentration - Most inexpensive to design and operate

Batch Reactor - Has a simple design, with the requirement of very little supporting equipments - Ideal for small scale experimental studies on reactor kinetics - Can be used industrially for treatment of very small quantities of materials.

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Feed

Product

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UNIT OPERATIONS/PROCESSESREACTOR UNITS

Unit operations/processes Functional role

Plug Flow Reactor (PFR) - Homogenous liquid/gas phase reaction - Reactant gradually reaches low concentrations - Good control over temperature - Temperature control through jacket

Packed Bed Reactor (PBR)

- Heterogeneous reaction - Packing to act as catalyst - Packing packed in tubes - Shell fed with cooling/heating fluid (optional) set alignment -continuous sentence

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ReactantsProductPlug

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UNIT OPERATIONS/PROCESSESREACTOR UNITS

Unit operations/processes Functional role

Trickle Bed Reactor (TBR)

- Multi-phase reaction -If the reaction is not catalytic, packing serves to enhance interfacial area - If the reaction is catalytic, packing acts as a catalyst as well - Complicated design

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UNIT OPERATIONS/PROCESSESREACTOR UNITS

Unit operations/processes Functional role

Fluidized Bed Reactor (FBR)

- Provides highest mass, heat and hence reaction rates for solid-fluid reactions - Very commonly deployed in petroleum refineries (catalytic cracking) - Complicated accessories (shown) and control system required - The accessories are for catalyst re-generation and transport.

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TYPES OF FLOW SHEETS

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ACKNOWLEDGEMENT

Slides are developed from the following references: Austin G. T., "Shreve’s Chemical Process Industries",

Fifth edition, Tata McGraw Hill, NY. Kent J.A., "Riegel's Handbook of Industrial

Chemistry,” CBS Publishers. Gopala Rao M. & Marshall Sittig, "Dryden’s Outlines

of Chemical Technology for the 21st Century", Affiliated East –West Press, New Delhi.

Mall I. D., "Petrochemical Process Technology", Macmillan India Ltd., New Delhi.

NPTEL (online)

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THANKS