Technical And Economic Comparison Between Cryogenic Nitrogen Production And Pressure Swing Adsorption Nitrogen Production

1. Process comparison
From the above discussion, we can find that the pressure swing adsorption nitrogen production process is simple, the number of equipment is small, the main equipment is only air compressor, air dryer, adsorption nitrogen machine and gas storage tank. The cryogenic nitrogen production process is complex, the number of equipment is large, the main equipment is air compressor, air cooler, air purification dryer, heat exchanger, expansion machine and fine flow tower.
Nitrogen making machine
2, product type and purity comparison
Cryogenic nitrogen production can not only produce nitrogen and can produce liquid nitrogen, satisfied with the process requirements of liquid nitrogen, and can be stored in the liquid nitrogen storage tank, when there is intermittent nitrogen load or air separation equipment minor repair, the liquid nitrogen in the storage tank into the carburetor is heated, into the product nitrogen pipeline to meet the needs of the process unit for nitrogen. The operation cycle of cryogenic nitrogen production (refers to the interval between two large heating) is generally more than 1 year, therefore, cryogenic nitrogen production is generally not considered as a backup. The pressure swing adsorption nitrogen production can only produce nitrogen, there is no backup means, a single set of equipment can not guarantee continuous long cycle operation.
Cryogenic nitrogen can produce nitrogen with purity of ≧99.999%. The purity of nitrogen is limited by the nitrogen load (de dan qi _dan qi chun du shou dao), the number of trays, the efficiency of trays and the purity of oxygen in liquid air, and the adjustment range is very small. Therefore, for a set of cryogenic nitrogen production equipment, its product purity is basically certain, and it is inconvenient to adjust. The purity of nitrogen produced by pressure swing adsorption is generally in the range of 95%-99.9%, and nitrogen purification equipment needs to be added if higher purity nitrogen is needed. The purity of nitrogen is only affected by the nitrogen load of the product. If other conditions remain unchanged, the greater the nitrogen discharge, the lower the purity of nitrogen. Otherwise, the higher it is. Therefore, for a set of pressure swing adsorption nitrogen production equipment as long as the load allows its product purity can be arbitrarily adjusted between 90-99.9%.
3. Operation control comparison
Since the cryogenic method is carried out at an extremely low temperature, there must be a pre-cooling startup process before the equipment is put into normal operation, and the startup time is generally not less than 12h from the startup of the expansion machine to the time when the nitrogen purity meets the requirements. Before the equipment enters the overhaul, there must be a period of heating and thawing time, generally 24h. Therefore, cryogenic nitrogen equipment should not start and stop often, and should run continuously for a long time. When the pressure swing adsorption method starts, as long as you press the button, you can get qualified nitrogen products within 30 minutes of starting, if you need high-purity nitrogen, then through the nitrogen purification device, you can get 99.99%-99.9999% high-purity nitrogen in about 30 minutes. Just press the button to stop the machine. Therefore, pressure swing adsorption nitrogen production is particularly suitable for intermittent operation.