During the absorption process, absorption can be categorized into physical absorption and chemical absorption based on the presence or absence of a chemical reaction during the operation.
As water absorption of CO2 (water washing), a physical absorption

The absorption tower is a unit equipment for the absorption process.
Divided into three categories based on gas-liquid contact forms
Firstly, tray towers, bubble absorption towers, and stirred bubble absorption towers where gas is dispersed in the liquid phase in the form of bubbles.
Secondly, injectors, Venturi tubes, and spray towers where liquids are dispersed in the gas phase as droplets.
Tray and downflow packed towers for liquid contacting with the gas phase in a film-like motion.
The flow pattern of gas-liquid two-phase inside the tower can be countercurrent or cocurrent.