Pressure Swing Adsorption (PSA) is a new type of gas adsorption separation technology. Using the adsorption difference of gas components on solid material and the changing of adsorption amount with pressure change, the gas separation and purification is achieved through periodic pressure changing process transformation.
Today，pressure swing adsorption is mainly used in the following nine areas ：
Purification of hydrogen;
Purification of carbon dioxide, food production and carbon dioxide;
Purification of carbon monoxide;
Transform gas removing carbon dioxide;
Natural gas purification;
Air separation oxygen;
Air separation nitrogen;
Gas concentrating methane
Concentration and purification of ethylene.
Principle of Pressure Swing Adsorption
Pressure swing adsorption is the method that in constant temperature, adsorption is realized in pressurized situation and desorption in depressurized (pumping) situation or ordinary pressure. So adsorption and desorption of PSA are realized by pressure changing. Due to small thermal conductivity of adsorbent, the temperature change of adsorbent bed that caused by adsorption heat and desorption heat is not big, so it can be seen as isothermal process. Its working condition is approximately in accordance with isotherm of normal temperature adsorption, with adsorption in high pressure and desorption in low pressure, and because of this, slope of adsorption isotherm has great influence on it in the view of static adsorption equilibrium, and in constant temperature, the effective adsorption capacity of linear isotherm is bigger than curve isotherm (Langmuir type) .
Vacuum pumps/ compressors application in PSA process
In boosting process, discharge port of vacuum pump is pressured and can be used as compressor entrance, usually it is installed in complete pump units.
In vacuum desorption, common pressure swing adsorption vacuum pumps are water ring pumps and reciprocating pumps.
1. Water ring vacuum pumps
They are usually used to relieve adsorption column of low vacuum in form of closed cycle units, with large capacity in low vacuum, which can meet system demand in short time. Besides, they are easy to operate and fulfill automatic and remote control.
2. Reciprocating vacuum pumps
Reciprocating pumps are usually used in adsorption column of high vacuum (-0.098MPa),and remain good performance due to special structure. They have advantages of less space occupation, no working medium and pollution, etc.