Oxygen Generation through Pressure Swing Adsorption (PSA) method is achieved by the use of a PSA Oxygen generation plant. Pressure swing adsorption makes use of molecular sieve pressure swing adsorption system where the molecular sieve acts adsorbent and uses ambient air at room temperature using Pressure Swing Adsorption.
Oxygen Generation Plants are simple and efficient means to produce the oxygen required to meet your needs on-site. This simple plant eliminates the need for transporting oxygen produced off-site and this helps to ensure a steady supply and control the supply of oxygen and translates to cost savings and high efficiency and maximum productivity. This also eliminates the use of bottled gas.
A PSA oxygen generation plant has two chambers where one chamber is pressurized, the other chamber is depressurized. This achieves the swing. This creates a continuous cycle of air between the vessels due to the air travelling from high pressure to low pressure vessel due to natural tendencies of air. The vessels contain molecular sieve that absorbs the nitrogen and becomes saturated. The oxygen s separated from air and the residual gas is expelled through the exhaust valve.
Pressure Swing Adsorption (PSA) is a technique by which a selected material is used as adsorbent like zeolite or activated carbon to selectively target and trap the molecule of gas present in air, in this case nitrogen and allow oxygen to pass through. This process takes place at ambient temperature and doesn’t need any external or additional heating or cooling as in cryogenic distillation which is commonly used for the process of separation of gasses. The adsorbent is selected on the basis of the affinity for the targeted gas to be adsorbed. The process is reversed when the pressure swings between the vessels and low pressure leads to the zeolite to desorb the gasses that were absorbed during the high pressure cycle.
The adsorbents can be Activated Alumina or Silica Gel. A unique characteristic of zeolite which makes it ideal for the process of oxygen generation and PSA as a whole is that it has the ability to absorb and retain nitrogen that is present in air and release it when de-saturated during the air cycle. This makes PSA a cost effective method and helps in repeated oxygen generation cycles.
A molecular sieve is a highly pores material with densely packed tiny holes of uniform size of small molecules which ensure that only tiny molecules can be adsorbed by the material while larger molecules pass through without being trapped. When the mixture of molecules, in this case air, pass through the sieve which is the bed of adsorbent, the semi-solid material, the molecules of larger weight pass through first as they will not be retained by the sieve, the smaller molecules then leave the bed.
The first or adsorption stage occurs in the adsorptive tower and occurs until the molecular sieve reaches its maximum saturation level beyond which the sieve will not be able to trap anymore nitrogen. The sieve allows the oxygen to pass into the collection tank under pressure. The collected oxygen will be at least 95% pure.
The next stage is basically a reversal of the first stage where by the adsorptive tower is depressurized and the zeolite is unsaturated with the help of the low pressure air which desorbs the zeolite. The rapid depressurization helps achieve this.
This process is contained within the two vessels and is controlled with the aid of automated controls which is used to open and shut valves to the tanks as and when required. The nitrogen gas separated is expelled from the vessel. The process is repeated by alternating the pressure levels in the vessels.
Why PSA Oxygen Plants
Self-sustained system which uses clean air at an ambient temperature. This means that it is very energy efficient.
Eliminates the need for a dedicated processing plant located remotely. This means that oxygen is produced at the location where it is needed and there is no need to store large quantities, saving cost and space.
Control of vital resources needed for production or service. Having to rely on third-party suppliers for important resource or raw material can be cumbersome whereas having control over it ensures smooth operation.