Concepts: Gas absorption and Desorption Flashcards
A unit operation where a soluble vapor is absorbed from its mixture with an inert gas by means of a liquid in which the solute is more soluble.
The solute is subsequently recovered from the liquid by distillation
Gas Absorption
Process of removing gas dissolved in a liquid and where the liberated gas is taken up in a gas or vapor in contact with the liquid.
It is the reverse of gas absorption
Desorption or Stripping
Equipment used (2)
- Plate Column
- Packed Tower
a plate column where gas is absorbed while a gas mixture bubbles through the liquid which passes down from plate to plate
Absorption Column
A parameter in the Kremser equation for calculation of absorption columns and towers; the product of the total pressure and the liquid flow rate in moles per second divided by the product of Henry’s Law constant and the gas flow rate in moles per second
Absorption Factor
A tower where liquid flows down over a packing material in countercurrent or co-current flow with a gaseous mixture while one or more of the gaseous components are absorbed in the liquid
Absorption Tower
Liquid which takes up one or more components from a gaseous mixture
Absorbent
The condition in which the packing surface is not wetted by the flowing liquid due to low liquid rates. It is the chief reason for the poor performance of large packed towers. It is severe in towers filled with packed stacking, which is the main reason they are not much used. It is less severe in dumped/random packings.
Chanelling
A tube or duct leading liquid from one plate in column to the next plate
Downcomer
In plate columns, excessive build-up of liquid on the plates caused by insufficient drainage through the downcomers
Downflow Flooding
In distillation and absorption, excessive carry-over of suspended droplets following the vapour or gas upwards through the column
Entrainment Flooding
In a given packed tower with a given type and size of packing and with a definite flow of liquid, this is the upper limit to the rate of gas flow. At flooding point, the liquid can no longer flow down through the packing and is blown out with the gas. In an actual operating tower, the gas velocity is well below flooding. The optimum economic gas velocity is about one-half or so of the flooding velocity.
Flooding Velocity
Outgoing gas mixture in air or gas absorption column/tower
Lean Gas
The point in a logarithmic pressure drop - gas velocity diagram for packed columns where the pressure drop start to increase more rapidly with increasing gas or vapor velocity caused by rapid increase in liquid hold-up. Further increase in gas or vapor velocity ends in flooding.
Loading Point
A column for distillation, absorption or extraction, consisting of a cylindrical shell filled with small objects (packing) to bring about intimate contact between rising fluid (vapor, gas, liquid) and descending liquid
Packed Column Tower
Small objects used to provide large contact area between rising fluid and descending fluid in packed columns, such as saddes, rings, grates, and pieces of coke
Packing
The outer diameter of propriety rings such as Raschig rings and pall rings. The size of saddles are given by number corresponding to one of the dimensions in inches
Packing Diameter