Air separation at room temperature can be divided into pressure swing adsorption method and membrane separation method. The former uses molecular sieves (mainly activated carbon) to remove most of the oxygen in the air because of their different adsorption capacities for oxygen and nitrogen under high pressure. The remaining nitrogen has a high purity, the oxygen content can be reduced to about 65438±0 ppm, and the nitrogen will also contain inert gases such as argon in the air. The required equipment is air compressor, purification equipment, adsorption tower, buffer tank, etc.
The other is membrane separation. Nitrogen films made of polymer materials have different seepage velocity for oxygen. When high-pressure air passes through the membrane tube, easily permeable gases such as oxygen and water quickly permeate out of the membrane, and the remaining nitrogen is discharged from the end of the membrane tube. The required equipment includes air compressor, purification equipment, nitrogen membrane, buffer tank, etc.
Low-temperature air separation is to use the different boiling points of various components in the air to liquefy the air first, and then distill and separate it according to the boiling points of different components. Low temperature air separation can obtain very high purity nitrogen and remove inert gases. Generally, the scale of cryogenic air separation equipment is large, and the larger the equipment, the lower the average energy consumption of nitrogen production. The required equipment is mainly air compressor, cooling tower, purification device, rectification tower, etc.