Method for preparing methanol by coupling gasification of pulverized coal waste boiler with green electricity and green hydrogen to realize near-zero carbon emission

Abstract

The invention relates to the field of methanol preparation with zero carbon emission, and particularly discloses a method for preparing methanol with near zero carbon emission by coupling gasification of a pulverized coal waste boiler with green electricity and green hydrogen, which comprises the following steps: oxygen generated by an air separation device and oxygen by-produced by a water electrolysis device react with coal in a gasification device of the pulverized coal waste boiler to obtain synthesis gas; the pulverized coal waste boiler gasification device recovers heat of high-temperature synthesis gas through a waste heat boiler and a steam superheater to produce high-pressure superheated steam, and the high-pressure superheated steam is sent to an air separation device to drive an air compressor turbine; the synthesis gas is conveyed to a heat recovery device for further heat recovery; the synthesis gas discharged from the heat recovery device is sent to a purification device, only sulfur-containing acid gas is removed, decarburization is not needed, and purified gas containing carbon monoxide, hydrogen and carbon dioxide is obtained; one part of electric energy generated by the new energy power generation system is transmitted to the water electrolysis hydrogen production device, one part is used by other electric facilities of the whole plant, and the rest part is transmitted to the energy storage device to be stored.

Description

technical field [0001] The invention belongs to a method for preparing methanol with near-zero carbon emission and environmental protection, and in particular relates to a method for preparing methanol with near-zero carbon emission through gasification of a waste boiler of pulverized coal coupled with green electricity and green hydrogen. Background technique [0002] As one of the important organic raw materials in the chemical industry, methanol has a huge annual demand. As of 2020, the national methanol production capacity has exceeded 87 million tons per year, and the output has exceeded 66 million tons. Due to the resource pattern of "poor oil, rich coal and little gas" in my country, the domestic production of methanol is mainly based on the coal-to-methanol route, accounting for about 76% of the country's total production capacity. The coal-to-methanol process widely used at present is: the oxygen generated by the air separation unit reacts with coal to generate crud...

AI Technical Summary

Problems solved by technology

[0003] In the above process, in order to obtain the raw material gas for methanol synthesis that meets the requirements of the hydrogen-to-carbon ratio, a part of carbon monoxide must be converted into hydrogen through a shift reaction. It can be seen from the reaction formula that when one mole of hydrogen is generated, one mole of carbon dioxide will be generated at the same time. The carbon dioxide produced by the reaction with coal gasification needs to be removed in the purification unit and discharged into the atmosphere. A large amount of carbon elements are not used and are directly wasted, and at the same time cause a large amount of carbon emissions

It is preliminarily estimated that the utilization rate of carbon in the raw coal of the traditional coal-to-methanol route is only about 40%.

[0004] At the same time, the coal gasification plant needs to be equipped with an air separation unit to provide the raw material oxygen required for the coal gasification reaction. Most of the air compressors, the core equipment of the large-scale air separation plant, are driven by steam. Therefore, the traditional coal-to-methanol plant needs to be equipped with a coal-fired boiler to supply high-pressure superheated steam. The carbon element in fuel coal is completely burned and emitted in the form of carbon dioxide, and the utilization rate of carbon element is zero

Images