Oxygen with Pressure Swing Adsorption
In PSA technology a specific gas species is separated from a mixture of gases under high pressure and at ambient temperature by passing the pressurized air through an adsorbent. Separation of gases is based on their different affinity for the adsorbent. At high pressure more gas is adsorbed, and when the pressure is reduced the gas is again released.
The adsorbents we use are ZMS and CMS for oxygen and nitrogen, respectively. Under normal operation conditions these molecular sieves are subject to practically no wear, and thus have minimal servicing requirements. The straightforward design and and construction of the units guarantee their reliability.
Oxygen PSA process can be described with following steps.
1. Compression, drying and filtering of input air:
The ambient air is compressed by an air compressor. Before entering the PSA process the compressed air is dried and filtered.
2. Oxygen adsorption on ZMS bed:
Our PSA units have two cylinders filled with Zeolite Molecular Sieve. (ZMS). Compressed and purified air is conducted to one of these cylinders. As the air flows through the cylinder, the Zeolite bed adsorbs nitrogen, while oxygen passes through to the oxygen accumulation tank. The adsorption process is interrupted before the ZMS becomes saturated with nitrogen by diverting the input air to the second cylinder, which at this point starts producing oxygen.
3. Nitrogen desorption and Zeolite bed regeneration:
The ZMS of the first cylinder (now saturated with nitrogen) is regenerated by reducing pressure in the cylinder below that of the adsorption step. The adsorbed nitrogen is released and vented into atmosphere. The regenerated adsorbent is then purged with oxygen from the second cylinder. After this step it is again ready for another cycle.
4. Oxygen accumulation in receiver tank:
Adsorption and desorption steps are repeated in the Zeolite tanks at equal time intervals. A constant flow of oxygen is conducted to oxygen receiver tank, which can store the oxygen to pressures up to 4-5 bar.
5. Oxygen pressurization:
From the receiver tank oxygen can either be fed to in-house gas network or bottled in cylinders. With our compressors pressures up to 300 bar can be reached.
The maximum oxygen purities reached with our systems are 93 ± 2 %. The oxygen produced is of medical grade, conforming to the United States Pharmacopeia Standard for "Oxygen 93 Percent". The standard Lasergas oxygen generation systems cover flowrates from 10 l/min to 1000 l/min. Even higher flowrates can be customized according to customer`s needs. Since the structure of our generator system is modular more gas production capacity can be added later if the demand increases. The outlet oxygen pressures can be tailored up to 300 bar.