Principle of nitrogen production by PSA variable pressure adsorption
The carbon molecular sieve can adsorb both oxygen and nitrogen in air, and its adsorption volume increases with pressure, and there is no significant difference in the equilibrium adsorption of oxygen and nitrogen at the same pressure. As a result, the effective separation of oxygen and nitrogen is difficult to accomplish with pressure changes alone. The adsorption properties of oxygen and nitrogen can be effectively distinguished if the adsorption rate is further considered. The diameter of oxygen molecules is smaller than nitrogen molecules, so the diffusion speed is hundreds of times faster than nitrogen, so the carbon molecule sieve adsorption of oxygen is also very fast, adsorption of about 1 minute to reach more than 90%; and at this time the amount of nitrogen adsorption is only about 5%, so the adsorption is largely oxygen, and the rest is largely nitrogen. In this way, if the adsorption time is controlled to less than 1 minute, oxygen and nitrogen can be separated initially, i.e., the adsorption and desorption are achieved by pressure difference, adsorption when the pressure rises and desorption when the pressure falls. The distinction between oxygen and nitrogen is made by the difference in the rate at which the two are adsorbed, which is achieved by controlling the adsorption time, which is very short, the oxygen is sufficiently adsorbed, and the adsorption process is stopped before the nitrogen has time to adsorb. Therefore, the change of pressure is necessary for the production of nitrogen by variable-pressure adsorption, and the time must be controlled to within 1 minute.
1. Process characteristics.
(1) Variable pressure adsorption nitrogen production equipment has the characteristics of wide gas source, high product purity, simple process, high degree of operation automation, low operating costs, etc.
(2) Compressed air purification components have a long service life and are easy to replace and maintain.
(3) The outlet flow rate of nitrogen production equipment is high and the outlet pressure can be adjusted within the set range.
(4) The machine can be driven or stopped at any time according to production conditions.
(5) Nitrogen purity >99.99% can be achieved by variable pressure adsorption without the need for nitrogen purification equipment.
(6) Add nitrogen purification equipment: hydrogen purification 丨 and carbon purification, the product qualified gas purity can reach ≥ 99.999%.
2. Technical design features.
(1) The unique molecular sieve dense filling technology and compression device are used to avoid the powdering of molecular sieve caused by the impact of molecular sieve in the high speed flow and improve the reliability of long-term operation of the system.
(2) Scientifically rational process and equipment configuration, compact equipment structure, beautiful appearance and small area.
(3) Low operating cost, stable and reliable nitrogen purity and flow rate.
(4) Air pretreatment part of the equipment, each stage filter with differential pressure indication, automatic drainage system.
(5) The equipment adopts standard parts to connect and disassemble, which makes installation and maintenance more convenient and convenient.
(6) Highly reliable inlet program-controlled valves with long service life can meet the needs of long-term stable operation of equipment.
(7) High degree of automation, using our self-developed microcomputer automatic program control system, the equipment can be operated automatically, and can adjust the nitrogen purity, pressure and flow rate according to the need.
(8) The equipment adopts aviation aluminum profiles for better use in the food and pharmaceutical industry or requires more accurate air source.
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