Question

In your own words, explain the functions of the following most frequently used unit operations in chemical engineering processes. (i) dryer, (ii) filter, (iii) distillation columns, (iv) absorber, (v) stripper, (vii) crystallizer, (viii) compressor, (ix) valve, (x) hydrocyclone

Answer 1

Dryer - It is an equipment which is used in drying unit operation. And drying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid, semi-solid or liquid.

Filter- It is an equipment which is used for filtration.And filtration is any of various mechanical, physical or biological operations that separate solids from fluids by adding a medium through which only the fluid can pass. The fluid that passes through is called the filtrate.

Distillation columns -It is an equipment which is used for Distillation. And Distillation is the process of separating the components or substances from a liquid mixture by selective boiling and condensation. Distillation may result in essentially complete separation (nearly pure components), or it may be a partial separation that increases the concentration of selected components of the mixture. In either case the process exploits differences in the volatility of the mixture's components. In industrial chemistry, distillation is a unit operation of practically universal importance, but it is a physical separation process and not a chemical reaction.

Absorber - It is an equipment which is used for Absorption. And absorption, or gas absorption, is a unit operation used in the chemical industry to separate gases by washing or scrubbing a gas mixture with a suitable liquid. One or more of the constituents of the gas mixture dissolves or is absorbed in the liquid and can thus be removed from the mixture.

Stripper - It is an equipment which is used for stripping. And stripping is essentially a distillation process where the heavy product is water/liquid and the lighter product is generally mixture of organic volatile materials. Generally steam/air is used for heating purpose in the column.

Crystallizer - It is an equipment which is used for crystallization. Andcrystallization is the (natural or artificial) process by which a solid forms, where the atoms or molecules are highly organized into a structure known as a crystal.

compressor - Compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor.

Valve - Valve is a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings, but are usually discussed as a separate category. In an open valve, fluid flows in a direction from higher pressure to lower pressure.

Hydrocyclone - It is a device to classify, separate or sort particles in a liquid suspension based on the ratio of their centripetal force to fluid resistance. This ratio is high for dense (where separation by density is required) and coarse (where separation by size is required) particles, and low for light and fine particles. Hydrocyclones also find application in the separation of liquids of different densities.