The air passes through the filter, compressor, cooler, oil-water separator, air precooler, molecular sieve adsorbent and enters the fractionator, and uses the different boiling points of liquid oxygen and liquid nitrogen to separate oxygen and nitrogen to obtain high-purity nitrogen. Cryogenic nitrogen machine running time is long, reduce the amount of maintenance, full low pressure process, energy saving, all aluminum fractionating tower, no leakage, imported air compressor and freezer unit.

The whole process of cryogenic nitrogen production is composed of three parts, namely, air tightening and purification, air separation, and liquid nitrogen vaporization.

1. Air tightening and purification

Cryogenic nitrogen production is the air through the air filter to remove dust and mechanical impurities into the air compressor, compressed to the required pressure, and then into the air cooler to reduce the air temperature. Then enter the air dry purifier to remove water, carbon dioxide, acetylene and other hydrocarbons in the air.

2. Air parting

The purified air enters the main heat exchanger in the air separation tower, is cooled to full temperature by the reflux gas (product nitrogen, waste gas), is sent to the bottom of the rectification tower, nitrogen is obtained at the top of the tower, the liquid air is saved and sent to the condensation evaporator to evaporate, and some nitrogen sent by the rectification tower is condensed together, and some of the condensed liquid nitrogen is used as the reflux liquid of the rectification tower. Another is produced as a liquid nitrogen product in the air separation tower.

The exhaust gas from the condensing evaporator is reheated by the main heat exchanger to about 130K expansion machine expansion refrigeration provides cold capacity for the air separation tower, and some of the expanded gas is used as regeneration and blowing cold of the molecular sieve, and then discharged into the atmosphere by the silencer.

3. Vaporization of liquid nitrogen

The liquid nitrogen from the air separation tower of the cryogenic nitrogen production equipment is stored in the liquid nitrogen storage tank. When the air separation equipment is repaired, the liquid nitrogen in the storage tank is heated into the carburetor and sent into the product nitrogen pipeline. Cryogenic nitrogen can produce nitrogen with purity of ≧99.999%.