Gas Absorption Process

Flashcards about Gas Absorption Process

Gas Absorption

Also called scrubbing, it is a mass transfer process involving the transfer of a substance from gas to liquid.

Stripping

The reverse of gas absorption.

Gas Absorption

One of the main techniques used in pollution control, where acid gas or water-soluble organic compounds are absorbed when it comes into contact with a liquid.

Physical Absorption Process

Process where a substance is physically dissolved in a liquid, such as removing acetone from an acetone-air mixture using water.

Chemical Absorption Process

Process involving a chemical reaction between the absorbed gas and the solvent, such as absorbing nitrogen oxides in water to produce nitric acid.

Absorption

Gas molecules diffuse into the liquid, and the movement in the reverse direction is negligible.

Distillation

Diffusion of molecules occurs in both gas and liquid directions.

Gas Solubility

The limit to the quantity of a pollutant that can be absorbed in a given amount of liquid at a specific temperature.

Gas Solubility

Gas solubility depends on temperature and pressure, increasing with pressure and decreasing at higher temperatures. It also varies for different gases with the same solvent.

Ideal Solvent Characteristics for Scrubbing

High gas solubility, low volatility, very low corrosiveness, low cost, low viscosity, and being non-toxic, non-flammable, and chemically stable.

Stripping

Also known as gas desorption, is a process where solutes absorbed from a gas mixture are desorbed to recover the solute and regenerate the solvent.

Stripping Conditions

Temperature may be increased or total pressure may be reduced during operation.

Scrubber Problems

Scale Deposition, Hypochlorite, Thermal Damage, and Salt Particles/SO3 Aerosols

Scale Deposition

Caused by operation with excessive dissolved solids, where salts produced during absorption combine with minerals in the water and exceed the solubility limit.

Hypochlorite Problem

Caused by improper wastewater treatment, where NaOCl attacks glass and breaks down into Cl2 in acidic liquid.

Thermal Damage

Caused by the use of inexpensive acid-proof materials in flue gas scrubbers. Failure of a quench system can result in burning or melting the scrubber internals.

Salt Particles / SO3 Aerosols

Caused by scrubbers not effectively removing small particles; SO3 forms tiny droplets of H2SO4 when quenched with water prior to scrubbing, acting like fine particles.