Product Description
Psa oxygen production equipment, under the condition of room temperature and atmospheric pressure, USES the special VPSA molecular sieve to selectively absorb nitrogen, carbon dioxide and water and other impurities in the air, so as to obtain oxygen with high purity (93±2%).
Traditional oxygen production generally adopts cryogenic separation method, which can produce oxygen with high purity. However, the equipment has high investment, and the equipment operates under the state of high pressure and ultra-low temperature. The operation is difficult, the maintenance rate is high, and the energy consumption is high, and it often needs to go through dozens of hours to normally produce gas after starting.
Since psa oxygen production equipment entered the industrialization, the technology has developed rapidly, because its price performance than in the low yield range and the purity requirements are not too high in the situation has a strong competitiveness, so it is widely used in the smelting, blast furnace oxygen enrichment, pulp bleaching, glass furnace, wastewater treatment and other fields.
Domestic research on this technology started earlier, but in a long period of time the development is relatively slow.
Since the 1990s, the advantages of psa oxygen production equipment has been gradually recognized by the Chinese people, and in recent years, various processes of equipment have been put into production.
The psa VPSA oxygen production equipment of Hangzhou Boxiang Gas Equipment Co., Ltd. has a leading position in the field of fertilizer industry, and its effect is very remarkable.
One of the main development directions of psa is to reduce the amount of adsorbent and improve the production capacity of the equipment. However, the improvement of molecular sieves for oxygen production is always carried out in the direction of high nitrogen adsorption rate, because the adsorption performance of molecular sieves is the basis of PSA.
The molecular sieve with good quality should have high nitrogen and oxygen separation coefficient, saturation adsorption capacity and high strength.
Psa another major development direction is to use short cycle, it needs not only guaranteed quality of molecular sieve, at the same time should be based on the adsorption tower internal structure optimization, in order to avoid which may cause the product to get bad and the disadvantages of non-uniform distribution of gas concentration in the adsorption tower, and also put forward higher requirements for butterfly valve switch.
In many PSA oxygen production processes, PSA, VSA and VPSA can be generally classified into three types.
PSA is the super large pressure adsorption atmospheric desorption process. It has the advantages of simple unit and low requirements for molecular sieves, and the disadvantages of high energy consumption, which should be used in small equipment.
VSA, or atmospheric pressure adsorption vacuum desorption process, has the advantage of low energy consumption and the disadvantage of relatively complex equipment and high total investment.
VPSA is the process of vacuum desorption through atmospheric pressure. It has the advantages of low energy consumption and high efficiency of molecular sieve. The total investment of equipment is much lower than that of VSA process, and the disadvantages are relatively high requirements for molecular sieve and valve.
Hangzhou Boxiang gas adopts VPSA process, and makes great improvement on the traditional process and process, which not only reduces the energy consumption to the minimum (refers to the use of the same brand molecular sieve), but also achieves the goal of simplification and miniaturization of equipment, reduces the investment, and has a higher performance/price ratio.
The whole psa oxygen production system is mainly composed of blower, vacuum pump, switching valve, absorber and oxygen pressure booster unit of oxygen balance tank.
After dust particles are removed by suction filter, raw air is pressurized to 0.3~0.4 Barg by Roots blower and enters one of the adsorbents.
The adsorbent is filled in the adsorbent, in which water, carbon dioxide, and a small amount of other gas components are adsorbed at the inlet of the adsorbent by the activated alumina on the bottom, and then nitrogen is adsorbed by the activated alumina and zeolite on the top of the 13X molecular sieve.
Oxygen (including argon) is the non-adsorbed component and is vented from the top outlet of the adsorber to the oxygen balance tank as a product.
When the adsorbent is adsorbed to a certain extent, the adsorbent will reach saturation state. At this time, vacuum pump will be used to vacuum the adsorbent through the switching valve (contrary to the direction of adsorption), and the vacuum degree is 0.45~ 0.5BARg.
The absorbed water, carbon dioxide, nitrogen and a small amount of other gas components are pumped out into the atmosphere and the adsorbent is regenerated.
Each adsorber alternates between the following steps:
- adsorption
- desorption
- stamping
The above three basic process steps are automatically controlled by PLC and switching valve system.
Working Principle
The above three basic process steps are automatically controlled by PLC and switching valve system.
1. Principle of psa air separation to produce oxygen
The main components in the air are nitrogen and oxygen. Therefore, adsorbents with different adsorption selectivity for nitrogen and oxygen can be selected and appropriate technological process can be designed to separate nitrogen and oxygen to produce oxygen.
Both nitrogen and oxygen have quadrupole moments, but nitrogen's quadrupole moment (0.31 A) is much larger than oxygen's (0.10 A), so nitrogen has A stronger adsorption capacity on zeolite molecular sieves than oxygen (nitrogen exerts A stronger force with ions on the surface of zeolite).
Therefore, when air passes through the adsorption bed containing zeolite adsorbent under pressure, nitrogen is adsorbed by the zeolite, and oxygen is less absorbed, so it is enriched in the gas phase and flows out of the adsorption bed, making oxygen and nitrogen separate to obtain oxygen.
When the molecular sieve adsorbs nitrogen to near saturation, the air is stopped and the pressure of the adsorption bed is reduced, the nitrogen adsorbed by the molecular sieve can be desorbed out, and the molecular sieve can be regenerated and reused.
Oxygen can be produced continuously by switching between two or more adsorption beds.
The boiling point of argon and oxygen is close to each other, so it is difficult to separate them, and they can be enriched together in the gas phase.
Therefore, the psa oxygen production device usually can only obtain the concentration of 80% ~ 93% oxygen, compared with the concentration of 99.5% or more oxygen in the cryogenic air separation device, also known as oxygen-rich.
According to different desorption methods, psa oxygen production can be divided into
Two Processes
1. PSA process: pressure adsorption (0.2-0.6mpa), atmospheric desorption.
PSA process equipment is simple, small investment, but low oxygen yield, high energy consumption, suitable for small-scale oxygen production (generally < 200m3/h) occasions.
2. VPSA process: adsorption under normal pressure or slightly higher than normal pressure (0 ~ 50KPa), vacuum extraction (-50 ~ -80kpa) desorption.
Compared with PSA process, VPSA process equipment is complex, high investment, but high efficiency, low energy consumption, suitable for large scale oxygen production occasions.
For the actual separation process, other trace components in the air must also be considered.
The adsorption capacity of carbon dioxide and water on ordinary adsorbents is generally much greater than that of nitrogen and oxygen. The adsorbents can be filled in the adsorption bed with appropriate adsorbents (or the use of oxygen making adsorbents themselves) so that they can be absorbed and removed.
General technical Overview of VPSA oxygen production equipment:
Ø adopt advanced technology, mature technology, low energy consumption and operation costs of two tower process psa oxygen generation process;
Ø reasoning and, through examination of form a complete set of equipment, high quality to ensure the reliability and stability of the system operation;
Ø equipment, convenient operation flexibility;
Ø highly automated process control, the centralized management of central control room;
Good Ø system security, equipment monitoring, fault prevention measures to improve;
Ø without environmental pollution;
Ø oxygen equipment to perform final publication of the People's Republic of China national standards and ministerial standard of mechanical industry.
