Process for production of dimethyl ether and combined production of natural gas and urea from coal-based synthetic gas and coke oven gas

Abstract

The invention provides a process for production of dimethyl ether and combined production of natural gas and urea from coal-based synthetic gas and coke oven gas. The process comprises the following steps: introducing coke oven gas and coal-based synthetic gas into a gasometer and carrying out uniform mixing to form crude raw material gas; carrying out compression and then purification and recovering removed hydrogen sulfide after removal of sulfur; and subjecting purified crude raw material gas to cryogenic separation so as to obtain clean raw material gas, preparing liquefied natural gas or compressed natural gas products from separated methane, synthesizing dimethyl ether from the clean raw material gas and subjecting purge gas produced after synthesis of the dimethyl ether to pressure-variable adsorption and separation, wherein separated CO and H2 are returned and purified, and separated CO2 and liquefied ammonia enter a urea synthesis apparatus for synthesis of urea. The process has the advantages of diversification of products and capacity of adjusting excess production power, facilitating energy conservation and emission reduction, regulating energy structure, increasing the utilization rate of raw material gas and reducing production cost for dimethyl ether.

Description

technical field [0001] The invention belongs to a process for producing dimethyl ether from coal-based synthesis gas and coke oven gas and co-producing natural gas and urea. technical background [0002] Dimethyl ether is an important chemical product with excellent combustion performance and can be used as a substitute fuel for diesel to achieve clean combustion. DME is known as "the clean fuel of the 21st century". The traditional DME production technology is to first synthesize methanol from syngas, and then convert methanol to DME by dehydration, which is the so-called two-step DME process. With the advancement of technology, a new technology for the direct production of dimethyl ether from synthesis gas, that is, a one-step dimethyl ether production process, has been developed. The two reactions of methanol synthesis and methanol dehydration are carried out in the same reactor without intermediate processes. , directly synthesize dimethyl ether from synthesis gas. Sin...

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Problems solved by technology

[0009] The production method of the present invention can make full use of the characteristics that coke oven gas has more hydrogen and less carbon, while the syngas has more carbon and less hydrogen, and complements the advantages of the two, and mixes them in a certain proportion to meet the hydrogen-carbon ratio of synthesizing dimethyl ether, so as to solve the problem of separate The use of coke oven gas to produce dimethyl ether requires carbon supplementation or the use of coal-based synthesis gas alone to produce dimethyl ether requires hydrogen supplementation. At the same time, it can by-produce LNG (liquefied natural gas) or CNG (compressed natural gas)

It can also react carbon dioxide gas produced in the production process of synthetic dimethyl ether with liquid ammonia to produce synthetic urea, so as to improve the utilization rate of raw material gas and overcome the shortcomings of the existing one-step production process of dimethyl ether

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