Internal compression air separation process is a process form in which liquid products are pressurized by liquid pump in the cold box, and then sent out of the cold box after reheating by high-pressure heat exchanger. The working pressure of internal compression process generally exceeds the critical point of oxygen and nitrogen. Heat transfer of liquid in supercritical state is a major feature of internal compression process. In the distillation process, due to the difference of product types and acquisition methods, there is a big difference between the material import and export of internal equipment and external compression process. In the internal compressed air separation process, the pressure of oxygen is not limited, the maximum output of nitrogen can reach 2.8 times of that of oxygen, and the extraction rate of argon can reach about 85%.
The internal compression air separation process is generally composed of internal compression system, air precooling system, molecular sieve purification system, distillation system, product compression system and storage and vaporization system. There are three kinds of process forms: single pump process of air pressurization; double pump process of air pressurization; single pump process of nitrogen circulation.
1.Single pump process of air pressurization: it refers to the internal compression of medium and high pressure oxygen, external compression of medium and high pressure nitrogen, extraction of pressurized nitrogen from the column, and extraction of low-pressure nitrogen on the column.
2.Double pump process of air pressurization: it refers to the internal compression of medium and high pressure oxygen and medium and high pressure nitrogen. The pressurized nitrogen is extracted from the columnand the low pressure nitrogen is extracted from the column.
3.Single pump process of nitrogen circulation: it refers to the internal compression of medium and high-pressure oxygen, external compression of medium and high-pressure nitrogen, extraction of pressurized nitrogen from the lower column, and extraction of low-pressure nitrogen from the upper column, the combination of circulating nitrogen compressor and product compressor.
