Air separation process capable of reducing energy consumption

Abstract

The invention relates to an air separation process capable of reducing energy consumption. A rectifying tower adopted for air separation comprises a high-pressure lower tower and a low-pressure uppertower. The air separation process is characterized by comprising the following steps that after pretreated air is cooled by a main heat exchanger, the cooled air is fed into the rectifying tower fromthe bottom of the high-pressure lower tower to be rectified, nitrogen and oxygen components are separated out; the low-pressure upper tower is communicated with an external liquid nitrogen storage device, liquid nitrogen in the liquid nitrogen storage device is fed into the low-pressure upper tower from the top of the low-pressure upper tower, an expansion machine is further arranged to be sequentially communicated with the main heat exchanger and the high-pressure lower tower, and part of nitrogen generated at the top of the high-pressure lower tower is pumped out and then is conveyed to theexpansion machine through the main heat exchanger. According to the air separation process capable of reducing the energy consumption, high-purity normal-pressure or under-pressure nitrogen products can be produced through recycling of liquid nitrogen cooling capacity, oxygen products and liquid oxygen products can also be obtained, and the production efficiency is remarkably improved.

Description

technical field [0001] The invention relates to the technical field of air separation, in particular to an air separation process for reducing energy consumption. Background technique [0002] Air separation refers to the process of separating components such as oxygen, nitrogen, argon, helium and other rare gases from air by using the difference in physical properties of the components in the air and applying the principle of cryogenic refrigeration. Among them, the method of producing oxygen and nitrogen by low-temperature rectification and separation of air is widely used in the actual production of large-scale air separation systems. Usually, a thermally coupled double-tower process of high-pressure lower tower and low-pressure upper tower is used to produce oxygen and nitrogen double-high products. That is, high-purity pressurized nitrogen with low boiling point is produced by rectification separation, and high-purity low-pressure nitrogen, high-purity or oxygen-enriche...

AI Technical Summary

Problems solved by technology

[0003] However, the existing air separation process design is mainly based on the production purpose of oxygen and nitrogen double-high products. Although it can produce double-high products, the energy consumption generated at the same time is relatively high; New processes such as oxygen-enriched combustion cannot efficiently produce high-purity nitrogen products, and the liquid production ratio of the double-tower double-high process and the oxygen-enriched process is limited

At the same time, for the occasion of gas supply after the liquid nitrogen in the liquid nitrogen storage tank is vaporized, the air vaporizer is commonly used to vaporize the liquid nitrogen, resulting in direct waste of liquid nitrogen cooling capacity

Although there have been reports on the use of liquid cooling capacity, they only use the cooling capacity of the liquid and do not make full use of the rectification potential of the upper tower, so that the energy consumption is still high, and the simultaneous production of high-purity gas is not considered. product

Images