Gas separation by adsorption systems is based on the fixation of various gas mixture components by a solid substance called adsorbent. Physically, this phenomenon is brought about by the forces of gas and adsorbent molecules interaction.
The current methods of gaseous oxygen production from air with the use of adsorption technology are nearly brought to perfection. The operation of a modern oxygen adsorption plant is based on the dependence of gas intake by adsorbent on the temperature and partial pressure of a gas component.
The gas adsorption and adsorbent regeneration processes may therefore be regulated by varying of the pressure and temperature parameters.
The oxygen plant flow process is arranged in such a way that highly absorbable gas mixture components are taken in by adsorbent, while low absorbable and non-absorbable components go through the plant. Today, there exist three methods of arranging the adsorption-based air separation process with the use of swing technologies: pressure (PSA), vacuum (VSA) and mixed (VPSA) ones. In the pressure swing adsorption flow processes, oxygen is recovered under above-atmospheric pressure and regeneration is achieved under In vacuum swing adsorption flow processes, oxygen is recovered under atmospheric pressure, and regeneration is achieved under negative pressure. The mixed systems operation combines pressure variations from positive to negative.
Some companies produce high-efficiency systems for oxygen production from atmospheric air with the help of membrane technology.
The basis of gas media separation with the use of membrane systems is the difference in velocity with which various gas mixture components permeate membrane substance. The driving force behind the gas separation process is the difference in partial pressures on different membrane sides.
A modern gas separation membrane used by GRASYS is no longer a flat plate, but is formed by hollow fibers. Membrane consists of a porous polymer fiber with the gas separation layer applied to its external surface. Structurally, a hollow fiber membrane is configured as a cylindrical cartridge representing a spool with specifically reeled polymer fiber.
Due to the membrane material high permeability for oxygen in contrast to nitrogen, the design of membrane oxygen complexes requires a special approach. Basically, there are two membrane-based oxygen production technologies: compressor and vacuum ones.
In the membrane oxygen plant, gas separation is achieved in the gas separation module composed of hollow-fiber membranes and representing the plant critical and high-technology unit. Apart from the gas separation unit, other important technical components are the booster compressor or vacuum pump, pre-purifier unit, and the plant control system.
The adoption of membrane systems for air enrichment purposes promises multiple oxygen savings where the oxygen concentration of 30-45% is sufficient to cover process needs. In addition to customer saving on the product oxygen cost, there is a collateral economic effect based on extremely low operating costs.
With the incorporation of the membrane technology, oxygen plants have outstanding technical characteristics. Membrane oxygen plants are highly reliable due to the absence of moving parts in the gas separation module.
The systems are very simple in operation – control of all operating parameters is carried out automatically. Because of the plants high automation degree, no constant manned attendance is required during its operation.
Membrane oxygen plants are finding increasingly broad application in various industries all over the world. With moderate requirements to oxygen purity in product - up to 30-45%, membrane systems generally prove more economically sound than adsorption and cryogenic systems. Besides, membrane plants are much simpler in operation and more reliable.
- Complete automation and simplicity of operation;
- No manned attendance required during operation;
- Enhanced failure safety and reliability;
- Quick start and stop ;
- Moderate dimensions and light weight ;
- Low noise level;
- Extended operational life;
- Low operating costs;
- No special workshop requirements;
- Easy installation and integration into an existing air system.