It has been long since the days of picking debris out of rice and wheat by hand. Today we have machines which use vibrations and weight differential of the husk and the rice in order to separate them. The separation process is an important part in any field because we need the respective material in its purest form for many reasons. The impurity might be harmful to organic life, it may completely alter the chemical composition of the required mater or the impurity by itself might be of great value.
Physical picking, boiling and condensation and distillation are few of the process used to separate different matter. As the matter got smaller in size and less dense we had to find new methods of separating them.
Pressure Swing Adsorption
Pressure Swing Adsorption is a separation process for gases, I which the pressure inside the separation chamber is used to separate the desired gas. Another method known as cryogenic distillation technique is used for the formation of liquid oxygen and liquid nitrogen but it operates at very low temperatures. Pressure Swing Adsorption, on the other hand, works at ambient temperature (surrounding temperature) for gas separation.
Adsorption and Absorption
One must not confuse absorption with adsorption.
Absorption is the process in which all the absorbed material is trapped within absorber like a sponge traps all of the water inside its structure. Adsorption, on the other hand, is trapping the material on the surface and doesn’t enter the adsorbent.
The best example of this is carbon capture carried out by activated carbon. There are other adsorbent materials which are used in this process like zeolites and molecular sieves.
This process uses the molecular property that in high-pressure gases is attracted to surfaces (like that of activated carbon) and the amount of adsorption is directly proportional to how high the pressure is. Once the desired material has been adsorbed under high pressure, the pressure is then reduced to release the trapped gas; hence it is called pressure swing because of the pressure changes from high to low.
This process is used for nitrogen removal from air using zeolite as the adsorption medium, to supply medical oxygen to patients with emphysema and in the removal of carbon dioxide as a final step in the industrial synthesis of hydrogen in oil refineries. Also, the same process could be used to capture all the methane in the air and be used as renewable natural gas. This technology could come handy in order to save the environment by reducing the greenhouse gases produced by industrial smoke. The research is still ongoing and will hopefully yield results soon.
Benefits of Pressure Swing Adsorption
The simplicity and ease of use of pressure swing adsorption machines is what makes it an ideal machine for production of nitrogen gas. It takes lesser space than a cryogenic gas separator and works on less energy. Also, companies who need nitrogen to product their products will have an abundant supply of it with just one of these machines.