Unit Operation and Unit Process

Unit Operation and Unit Process both are terms of Chemical Engineering. Chemical engineering involves the conversion of raw materials into your desired output at the least possible cost. To convert input into desired products we can classify chemical engineering into two parts -Unit operations and Unit processes. The unit operations concept was presented by Dr.Arthur D Little in 1915 while the concept of Unit processes was presented by P H Groggin in 1923.

 

The steps involving certain physical changes are termed UNIT OPERATIONS whereas the steps involving chemical changes in the materials under consideration are called UNIT PROCESSES.

Unit operations:-

Unit operations are related to physical changes of the materials involved, In any system when the physical changes occur or only the physical properties of a component are changed then that is called a unit operation. A general example of this is the boiling of water in which the physical state of water changes from liquid to vapor so we say that the boiling is a unit operation.

Chemical engineering unit operations consist of five classes:

1.   Fluid flow

·         Fluids transportation

·         Filtration

·         Solids fluidization.

2.   Heat transfer 

·         Evaporation

·         Heat exchange.

3.   Mass transfer 

·         Gas absorption

·         Distillation

·         Extraction

·         Adsorption

·         Drying

4.   Thermodynamic processes

·         Gas liquefaction

·         Refrigeration.

5.   Mechanical processes

·         Solids transportation

·         Crushing

·         Pulverization

·         Screening & sieving.

 

 Unit Process:-

Unit processes are those related to chemical changes of the materials. The unit process can be defined by those change that affects the chemical properties.

·         Neutralization

·         Oxidation / Reduction

·         Esterification / Saponification

·         Nitration

·         Sulfonation

·         Polymerization

·         Diazotization

·         Chlorination

·         Alkylation