Low temperature distillation separation method is currently the mainstream technology for industrial oxygen production, and its core principle is based on the difference in boiling points of various components in the air. The boiling point of oxygen is -183 ℃, and the boiling point of nitrogen is -196 ℃. Separation is achieved through deep freezing and distillation. The specific process is as follows:
Air compression and purification: Air is pressurized to 0.5-0.8 MPa through multi-stage compressors to improve liquefaction efficiency; Subsequently, moisture, carbon dioxide, and hydrocarbons are removed through a molecular sieve adsorption tower to prevent freezing and blockage of equipment at low temperatures.
Deep cooling and liquefaction: Compressed air enters the heat exchanger and exchanges heat with the reflux low-temperature nitrogen and oxygen, cooling down to around -170 ℃; Part of the air undergoes adiabatic expansion through a turbine expander, causing the temperature to drop sharply below -190 ℃, resulting in air liquefaction.
Distillation separation: Liquid air enters the two-stage distillation tower, and the oxygen rich liquid air at the bottom of the lower tower converges downwards due to its high boiling point, and is further separated after decompression; The nitrogen gas at the top of the upper tower rises due to its low boiling point, and ultimately obtains high-purity liquid oxygen (≥ 99.6%) at the bottom of the lower tower, while pure nitrogen gas is obtained at the top of the upper tower.
Product extraction: Liquid oxygen is pressurized by a liquid oxygen pump and reheated by a heat exchanger before being converted into gaseous oxygen for output, while nitrogen is directly transported through pipelines.
This technology is suitable for large-scale industrial production and can simultaneously produce high-purity rare gases such as oxygen, nitrogen, and argon. It has the advantages of low energy consumption and strong stability.
