Gas Absorption & Stripping Flashcards
Gas Absorption:
*When used
*Definition
*Regeneration
*When low solubility
*removal of solute or absorbate from gas via uptake by a non-volatile liquid (solvent or absorbent).
*Solvent regenerated by heating or stripping
Example of Absorption
Air-Ammonia Separation
*Ammonia to Liquid Water
Stripping
removal of a component from a liquid stream via vaporization and uptake by an insoluble gas stream.
Example of Stripping
Benzene-Oil Separation
*Benzene to Steam
Ideal Solvent for Absorption
- High Gas Solubility
- Chemically similar in structure
- Recoverability, Low Volatility, Inert, Low Viscosity
- Cheap
PACKINGS:
Random
dumped randomly in the tower.
PACKINGS:
Structured
Thin corrugated metal plates or gauzes, designed to force fluids on complicated paths throughout the column.
NTU
Number of Transfer Units
*High purity = High NTU needed
HTU
Height of a Transfer Unit
* High mass transfer coeff & Surface area = Lower HTU
Packed Absorption Tower
Vertical cylinder filled with a packing material.
*Higher area = More efficient
*LIQUID sprayed on top of tower, GAS fed at bottom
To increase the absorption, we increase ___ and decrease ___
INCREASE Liquid Flow
DECREASE Gas Flow
Degrees of freedom at plait point
0
Hunter Nash Method
Number of equilibrium stages required for a liquid-liquid extraction process.
How to determine Limiting Flow Rates for:
*Packed Columns
*Plate Columns
FIGURES ARE USED
*Packed Columns
Based on Generalized Pressure Drop Correlations
*Plate Columns
Based on flood capacity of different tray types
Assumption of Kremser Equation
Both equilibrium and operating lines are STRAIGHT
