Refrigeration of the cryogenic air separation equipment is realized by relying on the complete thermodynamic cycle to provide stable cooling capacity for air low-temperature separation.
The raw air first enters the compressor for multi-stage compression to increase pressure and energy, and then enters the precooling system for cooling, and the molecular sieve purification unit is used to remove water, carbon dioxide, acetylene and other impurities, so as to prevent these substances from freezing and blocking the equipment pipeline in the low temperature environment, and ensure the safe and stable operation of the system.
The purified high-pressure dry air enters the main heat exchanger for counter-current heat exchange with the low-temperature oxygen and nitrogen gas flowing back in the column, and the temperature drops rapidly. The core refrigeration of the equipment is realized by the expander: the high-pressure and low-temperature gas enters the expander for adiabatic expansion and external work, the internal energy is greatly reduced, and the temperature can be reduced to below - 170 ℃, so a large amount of cooling capacity is generated, which is the most important refrigeration mode of the air separation system.
Then, the gas is further throttled and cooled by the throttle valve with Joule-Thomson effect and partially liquefied. The cooling capacity is recycled and recovered in the system. Through continuous refrigeration and heat balance, the deep cooling environment of - 196 ℃ can be stably maintained inside the air separation equipment, providing necessary low-temperature conditions for rectification and separation of oxygen, nitrogen and other components, and realizing high-efficiency air separation and stable operation.
