Air separation process flow

After the dust and mechanical impurity in the air are removed by Du filter of air Bai, they are compressed to < 0.7mpa in an oil-free air compressor. The hot knife generated by the compression is taken away by the cooling water through the heat exchange of the water cooler, and then enters the pre-cooling unit for pre-cooling to (2~10) ℃. At this stage, part of the free water is separated and then switched into the molecular sieve purifier (MS1201 or MS1202). Water vapor, carbon dioxide, acetylene and other hydrocarbons remaining in the air are absorbed. The two adsorbents of the molecular sieve purifier are used alternately, one working and the other regenerative. The two sets of purifier adsorption cylinders are controlled by the program controller, and the timing is automatically switched.

The purified dry air temperature of the purifier rises to ~15℃. It is divided into two parts: most of the air goes into the air separation cooling box and conducts heat exchange with the backflow cold air flow (pure oxygen, pure nitrogen, sewage nitrogen, pressure nitrogen) in the main-board fin heat exchanger. The temperature drops to close to the liquefaction temperature and enters the lower tower after throttling through V1 valve.

Another part of the air into the supercharger turbo, after about 100 m3 / h gas as gas bearing gas turbine expander units, the rest into the cold box, and return air flow in the motherboard fin heat exchanger (pure oxygen, nitrogen, sewage, etc.) for heat exchange, and then through the middle extraction steam valve end suction valve V5 or V6 pulled out into the expansion of the expander refrigeration. The expanded air is sent to the tower through The V12 valve or into the sewage nitrogen pipeline through the V11 valve bypass, and then into the cold box after reheating through the main heat exchanger.

In the lower tower, the air is initially divided into liquid nitrogen and oxygen-rich liquid air. The nitrogen rising in the condensing evaporator exchanged heat with the low-pressure liquid oxygen at the bottom of the upper tower, and the low-pressure liquid oxygen liquefied and vaporized simultaneously. Liquid nitrogen is divided into two ways. One way enters the lower tower as backflow liquid through The V4 valve, and the other way enters the upper tower through the V3 valve after heat exchange between the cooler and pure nitrogen and dirty nitrogen. The oxygen-rich liquid gas of the lower tower is extracted from the bottom of the tower, and then sent to the upper tower as reflux liquid through V2 valve throttling after heat transfer and subcooling with pure nitrogen and sewage nitrogen.

After further distillation, high purity nitrogen is obtained at the top of the tower and oxygen is obtained at the bottom of the tower. The pure nitrogen is extracted from the top of the upper tower, reheated by the cooler and the main heat exchanger, and then sent to the cold box for compression filling or liquefaction. On the pollution of nitrogen from the upper tower, after cooler and the main heat exchanger to heat the cold box main heat exchanger, part as a purifier of angry again, another part of the vent, oxygen after reheat main heat exchanger, sent from the cold box compression filling or liquefied, after reheat pressure nitrogen through the main heat exchanger, the heater is sent out from the cold box.


Post time: Aug-31-2020
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