System and method for methanation of revolving-bed coal pyrolysis gas

Abstract

The invention relates to a system and method for methanation of revolving-bed coal pyrolysis gas. The system comprises a revolving-bed coal pyrolysis apparatus provided with a flue, a pyrolysis gas sampling and analyzing apparatus arranged in the revolving-bed coal pyrolysis apparatus, a pyrolysis gas methanation analyzing and controlling module connected with the pyrolysis gas sampling and analyzing apparatus, a flue opening-closing adjusting apparatus arranged on the flue of the revolving-bed coal pyrolysis apparatus, and a methanation apparatus comprising a gas inlet which is connected with the outlet of the flue of the revolving-bed coal pyrolysis apparatus. With the system and method provided by the invention, automatic adjustment of a hydrogen-carbon ratio of the pyrolysis gas is realized, and the hydrogen-carbon ratio of the pyrolysis gas is controlled in an ideal range of 3.15 to 3.20, meeting requirements of methanation of the pyrolysis gas.

Description

technical field [0001] The invention relates to the technical field of coal chemical industry, in particular to a system and method for methanation of coal pyrolysis gas in a rotating bed. Background technique [0002] my country's coal resources are very rich, of which low-rank coal accounts for a large proportion. Low-rank bituminous coal has high volatile content, high water content, easy oxidation, and easy weathering and fragmentation during storage and long-distance transportation, and the coal production area is far away from the coal consumption area, so low-rank bituminous coal is processed and utilized locally, and the production of high additional Products with high value, easy storage and transportation are the inevitable choice to realize the sustainable development strategy of my country's coal enterprises. [0003] From the perspective of coal reserves, coal quality characteristics, and social, economic and environmental conditions, the polygeneration technica...

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Problems solved by technology

[0005] In view of the above problems, the prior art one is to methanate coke oven gas, and its disadvantage is that the core of methanation is to adjust the gas hydrogen-carbon ratio (3.15-3.2), while the hydrogen-carbon ratio of coke oven gas is 6-7, hydrogen The content is too high, so that the methanation process in the production process needs to supplement carbon (supplement CO 2 ), so that the hydrogen-to-carbon ratio is within a suitable range

[0006] The second prior art is to methane the low-temperature pyrolysis gas in coal, and its disadvantages are: low-temperature pyrolysis in coal means that coal is pyrolyzed at 500-900°C, and the tar yield is as high as 6-7%. The species varies widely, but the hydrogen content is lower compared with high-temperature retort gas

The core process of low-temperature pyrolysis gas methanation in coal is the methanation process. The core of methanation is to adjust the gas hydrogen-carbon ratio (3.15-3.2), while the hydrogen-carbon ratio of low-temperature pyrolysis gas raw material gas in coal is about 0.9-1.5. Therefore, there are two ways to achieve a reasonable hydrogen-to-carbon ratio (3.15-3.2): supplementing hydrogen, and the price of hydrogen is very high, which will undoubtedly greatly increase production costs; decarbonization, removing excess CO from medium-low temperature pyrolysis gas 2 , this will not only increase the decarbonization system and increase the investment cost of methanation, but also cannot make efficient use of the effective components of low-temperature pyrolysis gas in coal

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