Improved process for producing ammonia synthesis gas from sodium cyanide tail gas

Abstract

The invention discloses an improved process for producing synthesis ammonia feed gas from sodium cyanide tail gas. The sodium cyanide tail gas contains 80-90% of hydrogen, 0.1-0.5% of carbon monoxide, 0.01-0.1% of carbon dioxide, 0.2-0.8% of oxygen, 0.01-0.3% of methane, 2-100 ppm of total sulfur, 2-100 ppm of total chlorine and the balance of nitrogen. The gas is fed into an organic sulfur conversion tower, the organic sulfur conversion tower is filled with a bifunctional conversion catalyst, organic sulfur higher than 0.01 ppm is completely converted into hydrogen sulfide, oxygen higher than 100 ppm is converted into water, crude converted gas is called as crude converted gas, the crude converted gas is fed into a hydrogen sulfide absorption tower to be reduced to 0.01 ppm, then the crude converted gas is fed into a trace oxygen conversion tower, the oxygen is lower than 1 ppm after conversion, and the crude converted gas is called as a post-converted gas; the post-converted gas is sent to a heat recovery device for heat recovery, then cooled to 20-50 DEG C, sent to an adsorption device for dehydration to 2-100 ppm and total chlorine less than or equal to 0.1 ppm, and then sent to a Fischer-Tropsch reactor, carbon monoxide and carbon dioxide in the gas are subjected to a Fischer-Tropsch reaction under 0.8-2.5 MPa, the total concentration of carbon monoxide and carbon dioxide in outlet gas is less than or equal to 20 ppm, and the gas is called Fischer-Tropsch gas; and the Fischer-Tropsch gas is sent to a pressure swing adsorption device to adsorb non-hydrogen nitrogen components to obtain hydrogen nitrogen, the concentration of the hydrogen nitrogen is larger than or equal to 99.95%, the total yield is larger than or equal to 96%, the total concentration of carbon monoxide, carbon dioxide, oxygen and water is smaller than or equal to 20 ppm, and the hydrogen nitrogen is used for preparing synthesis ammonia feed gas.

Description

technical field [0001] The invention relates to the fields of chemical industry, energy saving and environmental protection, and is a method for effectively reducing gas waste discharge and resource consumption. Background technique [0002] At present, the main component of the tail gas produced by the domestic production of sodium cyanide is hydrogen, which is mostly sent to the boiler room for burning and heating steam for production and living. Only using thermal energy wastes a lot of resources. Solving the high hydrogen tail gas, recycling resources is an urgent problem , and hydrogen nitrogen is an important raw material for the manufacture of synthetic ammonia. [0003] Yingkou Derui Chemical Co., Ltd. Liu Zicheng et al. CN212315560U announced a device for producing synthetic ammonia from sodium cyanide tail gas, including gas cabinet, purification system, first pressure swing adsorption hydrogen production device, pressure swing adsorption nitrogen production device...

AI Technical Summary

Problems solved by technology

[0008] The low-pressure methanation process is widely used in the coke oven gas to LNG process, but the service life of the catalyst is short, generally 6 months to 2 years

High-pressure Fischer-Tropsch is widely used in the coal-to-oil process, and the service life of the catalyst is short, generally 6 months to 2 years

Moreover, there is currently no case of low-pressure Fischer-Tropsch synthesis being applied to the purification of carbon monoxide and carbon dioxide

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