Air separation system utilizing LNG cold energy and air separation method

Abstract

The invention provides an air separation system utilizing LNG cold energy and an air separation method. An LNG cold box unit provides the LNG cold energy for a main heat exchanger cold box unit and a main tower cold box unit, and cooling liquefaction on air and nitrogen is achieved; the main heat exchanger cold box unit cools low-pressure purified air and pressure nitrogen, the low-pressure purified air is sent to a main tower for rectification and purification, liquid oxygen is obtained at the bottom of the tower, nitrogen is obtained at the top of the tower, an argon fraction is obtained in the tower, and the argon fraction is sent to an argon extraction part; the argon extraction part is used for deoxidizing, denitrifying and rectifying the argon fraction to obtain liquid argon; and circulating nitrogen and liquid nitrogen are circularly transmitted among the LNG cold box unit, the main heat exchanger cold box unit and the main tower cold box unit, so that the cold energy of LNG is transmitted, and meanwhile, part of liquid nitrogen products are obtained. According to the system and the method, single-tower rectification is adopted, the LNG cold energy is fully utilized to produce oxygen, nitrogen and argon products, a conventional lower rectification tower is omitted, investment is more saved, operation and maintenance are simpler, energy consumption is low, and safety is high.

Description

technical field [0001] The invention relates to the technical field of air separation technology, in particular to an air separation system and an air separation method utilizing LNG cold energy. Background technique [0002] LNG cold energy air separation, as a utilization method of LNG cold energy, has been widely promoted and applied in LNG receiving stations because of its low energy consumption and high income. And the new LNG cold energy air separation technology is also constantly being explored and optimized. [0003] The LNG cold energy air separation system mainly uses circulating nitrogen as the intermediate medium of cold energy transfer, and uses the air separation rectification tower to liquefy, separate and purify the purified air to obtain corresponding gas products. While circulating liquid nitrogen transfers cold energy from LNG to the air separation cold box system, it also provides a large reflux liquid for the air separation rectification tower, so ther...

AI Technical Summary

Problems solved by technology

However, the current LNG cold energy air separation system is too complex in terms of process organization. The air separation column is a two-stage distillation column with complicated internal reflux. The rectification potential of the reflux liquid is not fully utilized, and the operating pressure is high and energy The high energy consumption makes the equipment and facilities of the LNG cold energy air separation system require a large investment, high energy consumption for operation, and complicated operation and maintenance

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