Heat exchange system for cryogenic separation device for coal gasification device feed gas methane

Abstract

The invention discloses a heat exchange system for a cryogenic separation device for coal gasification device feed gas CH4, which comprises a plate-fin main heat exchanger, a mixed refrigerant circulating compressor and a nitrogen circulating compressor. A feed gas channel, a mixed refrigerant channel and a nitrogen channel are arranged in the main heat exchanger. The feed gas from an upstream coal gasification device is subjected to heat exchange in the main heat exchanger, is cooled by a reboiler, and enters the main heat exchanger to be further cooled and partially condensed to a washing tower. An inlet/outlet of the mixed refrigerant heat exchange channel in the main heat exchanger is connected to an inlet/outlet of closed mixed refrigerant circulation respectively. An inlet/outlet of the nitrogen heat exchange channel in the main heat exchanger is connected to an inlet/outlet of the nitrogen circulating compressor. Due to the adoption of the mode of combining the closed mixed refrigerant refrigeration cycle and the nitrogen refrigeration cycle and due to the use of an air-separation liquid nitrogen complementation method, the heat transfer temperature difference of the main heat exchanger can be improved, the irreversible loss of the main heat exchanger can be reduced, and the energy consumption of the whole set of the cryogenic separation device can be reduced.

Description

technical field [0001] The invention relates to the CH of raw material gas from a coal gasification device 4 The invention relates to a heat exchange system of a cryogenic separation device, which belongs to the technical field of low temperature gas separation. Background technique [0002] At present, the raw material gas from the coal gasification unit of the chemical plant is basically composed of CO and CH 4 、H 2 , due to the existence of methane gas, it is very unfavorable to use raw material gas to synthesize ammonia or synthesize methanol, which affects the synthesis rate of products and increases energy consumption. So it is required to change CH 4 and CO, H 2 Separation, so that the raw material gas must be cooled to -165 ° C ~ -160 ° C in the heat exchanger. Previous technologies mostly used a single closed mixed refrigerant refrigeration cycle or a nitrogen expansion refrigeration cycle. Contents of the invention [0003] The object of the present inventi...

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Problems solved by technology

[0002] At present, the raw material gas from the coal gasification unit of the chemical plant is basically composed of CO and CH 4 、H 2 , due to the existence of met...

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