Unit Operations Gas-Liquid Seperation

CHG 3111 Unit Operation

Gas-Liquid Separation Text Book: Chapter 10

Separation Processes
Introduction:
Many chemical and biological processes occur as a mixtures of different phases, gas, liquid and solid. To separate or remove one or more of the components from its original mixture, it must be contacted with another phase. The two phase pair can be gas-liquid, liquid-liquid or liquid-solid. When different phases are brought into contact, a solute or solutes can diffuse from on phase to the other. The phases are then separated by physical methods, where one phase is enriched while the other is depleted in one or more components.

Phase 2 Phase 1

Phase 2 Phase 1

Contact
CHG 3111/Poupak Mehrani

Separation
2

Separation Processes
Types of Separation Processes:
1. Absorption: Phases: Gas-Liquid Solute (or solutes) is absorbed from the gas into the liquid Absorption of ammonia from air by liquid water Absorption of SO2 from the flue gases by alkaline solutions Reverse of absorption is stripping or desorption (from liquid to gas) Steam stripping of nonvolatile oils, steam contacts with oil and small amounts of volatile components of the oil leave with the steam
Liquid (C) Gas (B)

Humidification (addition of water to air) Dehumidification (removal of water vapour from air)
A

Liquid (C+A)

Gas (A+B)
3

CHG 3111/Poupak Mehrani

Separation Processes
Types of Separation Processes:
2. Distillation: A volatile vapour phase and a liquid phase that vaporizes are involved. The vapor phase contains a higher concentration of the more volatile component while the liquid phase contains more of the less volatile component. Distillation of ethanol-water solution: vapour contains more ethanol than the liquid Distillation of ammonia-water solution: vapour richer in ammonia Distillation of crude oil: components such as gasoline, kerosene and heating oils are distilled off.
Distillate (A+ small amount of B)

Feed (A + B)

Bottoms (B+ small