Air separation method capable of being matched with cold energy supply in receiving station

Abstract

The invention discloses an air separation method capable of being matched with cold energy supply in a receiving station. The method includes the following steps that when LNG supply is sufficient, nitrogen from an air separation system is compressed many times and then exchanges heat with LNG, high-pressure supercooling liquid nitrogen can be obtained, and cooling capacity is provided for the air separation system; a stream of liquid nitrogen is extracted from the high-pressure supercooling liquid nitrogen and throttled and then exchanges heat with second stream of raw material air, the temperature of the liquid nitrogen rises so that low pressure nitrogen can be generated, the low pressure nitrogen is added into the nitrogen exchanging heat with the LNG, the temperature of the second stream of raw material air is lowered so that liquid air can be generated through liquidation, and the liquid air forms stock liquid air; when LNG supply is not sufficient, the stock liquid air is fed into an upper tower of the air separation system, cooling capacity and part of separation air are provided for the air separation system, no heat exchange happens between the LNG and the nitrogen from the air separation system at the moment, the LNG exchanges heat with cooling liquid of a raw material air compressor, and the LNG is fed into a natural gas pipeline after the temperature of the LNG rises to reach the pipeline conveying temperature. With the air separation method, the requirement of the air separation method for LNG cold energy can be well matched with supply of LNG cold energy.

Description

technical field [0001] The invention relates to an air separation method, in particular to an air separation method which utilizes the cold energy of liquefied natural gas, but the cold energy supply of the liquefied natural gas is unstable. Background technique [0002] Chinese invention patent document CN101943512B disclosed an air separation method utilizing the cold energy of liquefied natural gas on January 12, 2011. This air separation method requires continuous, uninterrupted and stable supply of cold energy of liquefied natural gas. However, the LNG at the receiving station is always gasified during the day, and the available cooling energy is abundant, and at night, the LNG is less gasified, and the available cooling energy is insufficient. This contradiction between the demand and supply of LNG cold energy has seriously affected the application of the above-mentioned air separation method utilizing LNG cold energy, and also seriously affected the full utilization o...

AI Technical Summary

Problems solved by technology

However, the LNG at the receiving station is always gasified during the day, and the available cooling energy is abundant. At night, the LNG gasification is less, and the available cooling energy is insufficient.

This contradiction between the demand and supply of LNG cold energy has seriously affected the application of the above-mentioned air separation method using LNG cold energy, and also seriously affected the full utilization of unstable LNG cold energy.

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