A method and equipment for producing air products based on cryogenic distillation

Abstract

The invention discloses a method and equipment for producing air products based on cryogenic rectification. Raw material air and nitrogen gas compressed by a compressor are cooled by a main heat exchanger and sent to a rectification system for low-temperature separation. In the rectification system, products such as oxygen and nitrogen are obtained through low-temperature separation, and oxygen-enriched liquid air will also be obtained at or near the bottom of the rectification tower. The oxygen-enriched liquid air or liquid air in the rectification system is raised to the target pressure by the cryogenic liquid air pump and then sent out, and then mixed with circulating nitrogen in the gas phase to produce air products of various pressures. Adopting this method can avoid the problem in the prior art that liquid nitrogen is mixed with oxygen-enriched liquid air or liquid air in the liquid phase, and it cannot be determined that the obtained air product is just the required ratio after vaporization; The air product is obtained in a more precise and safe manner using the compression process within the nitrogen cycle.

Description

technical field [0001] The invention relates to the field of cryogenic air separation, in particular to a method and equipment for producing air products based on cryogenic rectification. Background technique [0002] Cryogenic separation method, also known as low temperature rectification method, usually adopts mechanical methods, such as throttling expansion or adiabatic expansion, after compressing and cooling the gas, rectifying the difference in the boiling point of different gases, so that different gases can be separated. . [0003] The principle of cryogenic air separation is to use air as the raw material. After compression, purification and heat exchange, the air is liquefied into liquid air. Liquid air is mainly a mixture of liquid oxygen and liquid nitrogen. Using the different boiling points of liquid oxygen and liquid nitrogen, they are separated by rectification to obtain nitrogen and oxygen. [0004] In a specific coal chemical project, especially a synthet...

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Problems solved by technology

In theory, there is no problem in adjusting the nitrogen and oxygen content in the liquid phase according to the prior art, but it is more difficult in actual operation, because it cannot be determined that the obtained air product is just in the required ratio after vaporization, and the saturated liquid nitrogen and Oxygen-enriched liquid air or liquid air will produce bubbles after mixing, so it is not suitable to be directly fed into the pump for pressurization

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