Unit operations.pptx

This presentation helps to understand basic knowledge of unit operations.

1. Process engineering Unit operations & UNIT PROCESS Presented by: Neeraj Kumar Rai

2. UNIT OPERATIONS Unit operations involve a physical change or chemical transformation such as separation, crystallization, evaporation, filtration, polymerization , isomerisation etc. A unit operation is defined as a process which does not involve any chemical reaction. Unit operations only deal with physical changes of the materials involved in the process. They are equipments which cause the materials to undergo physical changes.

3. UNIT OPERATIONS The physical changes are carried out for variety of purposes. Generally unit operations steps are carried out before subjecting the materials to chemical reactions so that chemical reactions happen smoothly. The physical changes can imply phase changes such as; evaporation, condensation, crystallization etc. Thus Distillation is a unit operation step because condensation and evaporation happens inside the column. Evaporators, and crystallisers are also unit operations equipment. Unit operation equipments are also responsible for mechanical operations which involves size reduction, physical separations, mixing, and grinding. The mass transfer, heat transfer process all may happen together. Chemical reaction doesn’t happen.

4. History Arthur Dehon Little developed the concept of "unit operations" to explain industrial chemistry processes in 1916. In 1923, William H. Walker, Warren K. Lewis and William H. McAdams wrote the book The Principles of Chemical Engineering and explained that the variety of chemical industries have processes which follow the same physical laws .   The concept of unit processes was introduced in 1923 by P.H. Groggin .

5. UNIT OPERATIONS Chemical engineering unit operations consist of five classes Fluid flow processes, including fluids transportation, filtration, and solids fluidization. Heat transfer processes, including evaporation and heat exchange. Mass transfer processes, including gas absorption, distillation, extraction, adsorption, and drying. Thermodynamic processes, including gas liquefaction, and refrigeration. Mechanical processes, including solids transportation, crushing and pulverization, and screening and sieving. Chemical engineering unit operations also fall in the following categories which involve elements from more than one class: Combination (mixing) Separation (distillation, crystallization) Reaction (chemical reaction)

6. UNIT OPERATIONS The unit operations are classified in the following manner : Fluid flow operations: Pumping, compression, and fluidisation. Mechanical operations: Size reduction, size enlargement, mixing, agitation, blending, filtration, classification-separation, etc. Mass transfer: Distillation, evaporation, crystallization, leaching, absorption, adsorption, extraction, etc. Heat transfer: When materials are handled the heat transfer can take place by any fundamental mechanism; conduction, convection, or radiation. Usually two fundamental mechanisms occur simultaneously.

7. UNIT PROCESS A chemical reactor is an equipment which falls under the category of unit processes. C hemical change takes place inside the equipment wherein the chemical structure of the material changes and it transforms and forms an entirely new material. All kinds of chemical reactions carried out in industrial equipments comes under this category. Some examples of such chemical reactions are; sulphonation , nitration, halogenation , alkylation, hydrolysis, hydrogenation, polymerization, oxidation, reduction, etc.

8. Discussion of different unit operations Material handling, transportation / Fluid flow process Pumping Compression fluidization Mechanical unit operations Size reduction Size enlargement Mixing, agitation, blending, etc Mass transfer operations Evaporation Distillation Absorption Extraction leaching. Heat transfer operations conduction convection radiation