Non-isobaric ammonia synthesis and co-production of liquefied natural gas (lng) process

Abstract

The invention discloses a new process for non-constant pressure ammonia synthesis and co-production of liquefied natural gas (LNG). The process includes the steps of: a. compressing synthetic fresh gas, then introducing the compressed gas into a low pressure ammonia synthesis tower to conduct low pressure ammonia synthesis; b. mixing the vent gas of the low pressure ammonia synthesis tower with the compressed synthetic fresh gas of step a; c. carrying out recompression on the mixed vent gas and synthetic fresh gas to increase pressure, and then introducing the obtained gas into a high pressure ammonia synthesis tower to conduct high pressure ammonia synthesis; and d. recovering the synthetic ammonia tail gas to make liquefied natural gas (LNG). According to the process provided by the invention, the ammonia synthesis feed gases are subjecting to synthesis under different pressures so as to increase the hydrogen-nitrogen utilization rate; methane in the vent gas is fully utilized, and the production cost is lowered; emission and environmental pollution are reduced; and the ability of resisting market risk is improved.

Description

technical field [0001] The invention belongs to the field of synthetic ammonia, and particularly relates to an inert gas (mainly CH) contained in the fresh gas of an ammonia synthesis system 4 ), the ammonia synthesis system should be released for reasonable recycling. Background technique [0002] The ammonia synthesis reaction is a reversible reaction of exothermic and volume reduction, and temperature and pressure affect the chemical balance of this reaction. [0003] The reaction formula for ammonia synthesis is: [0004] [0005] At present, the ammonia synthesis process used in industry is mainly divided into two types according to different purification processes. [0006] One is the use of cryogenic purification process, which is characterized by almost zero inert gas in the fresh gas of ammonia synthesis. The characteristics of this ammonia synthesis process are: [0007] ①The ammonia synthesis pressure can be controlled at 10.0~15.0MPa; [0008] ②The ammonia...

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Problems solved by technology

[0014] ②The circulating air volume is too large, and the circulating power consumption increases;

[0015] ③ The net value of ammonia is relatively low, the equipment is large, and the amount of catalyst used is large, so the investment is relatively high

[0016] ④Large air volume

[0018] ① Compressing hydrogen and nitrogen to high pressure for synthesis will significantly increase the compression work;

[0019] ②The requirements for equipment and materials are relatively high, which is not conducive to the large-scale development of ammonia synthesis equipment;

[0020] Therefore, there are obvious shortcomings in the two ammonia synthesis processes that use different pressures when using the double methyl purification process.

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