Method for preparing methane by catalyzing and gasifying coal

Abstract

The invention relates to a method for preparing methane by catalyzing and gasifying coal. The method sequentially comprises the following two steps: 1, successively or simultaneously carrying out preoxidation and ion exchange treatment on coal in a slurry containing coal and water; and 2, gasifying the product obtained in step 1 by sending it to a gasification furnace which sequentially comprises a gas generation segment, a coal methanation segment, a synthetic gas methanation segment and an optional coal pyrolysis segment from bottom to top to obtain a gas product containing methane.

Description

technical field [0001] The invention relates to the field of preparing substitute natural gas by coal gasification, in particular to a method for preparing methane by catalytic coal gasification, and more specifically, to a method for preparing methane by catalytic gasification of pretreated coal in a multi-stage gasification furnace. Background technique [0002] With the rapid development of the economy and increasingly stringent environmental protection regulations, my country's demand for natural gas, a clean energy source, will grow explosively in the next ten years. Although the production of natural gas has increased, it is far below the growth trend of demand. The contradiction is becoming more and more prominent, and the supply gap is increasing year by year. In view of the characteristics of my country's energy resource status of "rich in coal, low in oil, and lack of gas", the long-term maintenance of coal-based energy consumption structure will not change in the s...

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Problems solved by technology

[0006] The disadvantages of the above process are: due to the addition of a catalyst to promote methane generation, but high temperature is not conducive to the generation of methane, the reaction temperature is generally controlled at about 700 ° C, the reaction speed is slow, and the conversion rate of carbon is low. If there is no external heating system to provide heat, it will be very difficult. It is difficult to maintain the reaction temperature, and these technologies are still in the research and development stage

U.S. Patent US 4407206 relates to a coal partial combustion process, which proposes to pre-oxidize the coal powder in a fluidized bed, the temperature is controlled at 200 ° C, and after 24 hours of pre-oxidation, the coal powder is mixed with an aqueous solution of calcium acetate, and after drying It enters into a partial combustion device for reaction, the pre-oxidation time is long, it takes two to three days, and the calorific value loss of coal is relatively large, about 20-30%

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