About Oxygen Concentrators
An oxygen concentrator is a device that concentrates oxygen from a gas supply (usually ambient air) by selectively removing nitrogen to provide a stream of oxygen-rich products. They were created to replace compact high-pressure oxygen cylinders or small cryogenic liquid oxygen systems, allowing patients using medical oxygen therapy to receive treatment at home. Oxygen concentrators consist of an air compressor, two cylinders filled with zeolite pellets or beads, a pressure equalization reservoir, and a number of valves and tubing.
There are two main types of zeolite molecular sieves for oxygen concentrators on the market, sodium and lithium type molecular sieves. Lithium-type zeolite molecular sieves are more efficient than sodium-type zeolite molecular sieves and can greatly reduce the size of the oxygen concentrator, making it smaller and more portable. Since lithium type molecular sieves are much more expensive than sodium type molecular sieves, sodium type oxygen molecular sieves are also prevalent in the market for most situations.
Why Zeolite is Used in Oxygen Concentrator?
Zeolite is the essence of the oxygen concentrator. Oxygen concentrators use molecular sieves composed of zeolites to adsorb nitrogen from the atmosphere, which is subsequently expelled. Thus, this type of adsorption system is functionally a nitrogen scrubber, allowing other atmospheric gases to go through. This leaves oxygen as the principal remaining gas. Under high pressure, the porous zeolite adsorbs a large amount of nitrogen due to its larger surface area and chemical properties. Afterwards, oxygen and other free components are collected and the pressure drops, allowing the nitrogen to desorb. In a modest way, zeolites act as a filter for nitrogen molecules.
Zeolites are widely used in PSA systems thanks to their ability to differentiate between different gas and their large specific surface area. In addition, their porosity plays a critical role in the adsorption process. The regular arrangement of pores and cavities (micropores) assembled from SiO4 and AlO4 tetrahedral structures allows some molecules to be selectively absorbed in the micropores, while others are rejected due to steric effects or differences in affinity, as in the case of oxygen concentrators, where nitrogen is adsorbed on the zeolite while oxygen passes through.
What's the Difference of PSA and VPSA Oxygen Concentrator?
PSA and VPSA technologies are two common methods of oxygen production that use zeolite molecular sieves. Through variable pressure, nitrogen and oxygen in the air are separated in the adsorption and desorption process to obtain high purity oxygen. Compared with VPSA oxygen generation equipment, PSA equipment has a low initial investment, but high energy consumption and high maintenance cost in a later operation. When the oxygen demand is large. PSA equipment no longer has economic advantages due to its large area and high energy consumption.
Strictly speaking, VPSA oxygen generation is another "variant" of PSA oxygen generation, and their oxygen generation principles are almost the same, both using molecular sieve to separate the gas mixture by "adsorption" of different gas molecules, except that PSA oxygen generation is through The PSA oxygen generator separates oxygen by pressurized adsorption and desorption at atmospheric pressure, while the VPSA oxygen generator desorbs the adsorbed saturated molecular sieve under vacuum conditions.
Although both of their use air as raw material and the principle of oxygen production is similar. However, when compared carefully, there are the following differences.
First, PSA oxygen generators use air compressors for air supply, while VPSA oxygen generators use blowers to obtain authentic air and pressurize it.
Secondly, in the choice of zeolite molecular sieve, the PSA oxygen generator uses sodium molecular sieve and the VPSA oxygen generator uses lithium molecular sieve.
In addition, in terms of adsorption pressure, PSA oxygen generators usually have 0.6~0.8Mpa, while VPSA oxygen generators have 0.05Mpa.
Furthermore, in terms of single machine gas production, PSA can reach 200~300Nm/h, while VPSA can reach 7500~9000Nm/h.
Finally, compared to PSA, VPSA is relatively low in energy consumption (≤0.5 kW of electricity consumption per cube of oxygen produced), more environmentally friendly and green.
