Coal underground gasification method

Abstract

The invention relates to a coal underground gasification method. The coal underground gasification method comprises the following sequential steps of (1) establishing a gas inlet passage, a gas outlet passage and a gasification passage which enables the gas inlet passage to be communicated with the gas outlet passage; (2) injecting a gasification agent through the gas inlet passage, wherein the gasification agent comprises water vapor and oxygen-enriched gas, and an initial volume ratio between the water vapor and the oxygen-enriched gas ranges from 0.5 : 1 to 4 : 1; (3) igniting a coal seam; (4) forming a new volume ratio by adjusting the ratio between the water vapor and the oxygen-enriched gas according to the characteristics of generated coal gas. According to the coal underground gasification method disclosed by the invention, a little water vapor is enabled to be carried in raw coal gas, the cost for recovering waste water in raw coal gas is reduced, the situation that the water vapor and the coal seam are in full reaction so as to generate hydrogen can be ensured, and thus the quality of coal gas can be increased; in addition, the temperature uniformity on a gasification working surface can be ensured due to reactions, i.e. exothermic reaction of oxygen and the coal seam and endothermic reaction of water and the coal seam, which are carried out in the same time, and the phenomenon that the continuous gasification of the coal seam is obstructed as gasification coal ash is melted and attached to a gasification coal wall due to over-high local temperature can be prevented from happening.

Description

technical field [0001] The invention relates to an underground coal gasification method. Background technique [0002] Underground coal gasification technology is a technology that converts underground coal into combustible gas in situ through thermochemical reactions. In the specific implementation process, a plurality of channels are usually established, and they are respectively used as the inlet channel and the gas outlet channel, and then the gasification channel is connected to the inlet channel and the gas outlet channel, and the coal seam is ignited and the gasification agent is sent to the inlet channel, and the generated Combustible gas (coarse gas) is discharged to the ground through the gas outlet channel. The combustion reactions carried out in the gasification channel here are mainly: [0003] C+H 2 O(g)=CO+H 2 -131.5MJ / kmol (1) [0004] C+1 / 2O 2 =CO+110.9kJ / mol (2) [0005] During the underground coal gasification process, the temperature of the crude g...

AI Technical Summary

Problems solved by technology

Although the invention utilizes the adjustment of O in the gasification agent 2 The concentration controls the temperature in the underground combustion zone, but does not take into account the minimization of heat energy loss in the underground gasification process

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