Underground coal gasification device and gasification method thereof

Abstract

The invention provides a coal underground gasification device and a gasification method of the coal. The device comprises an air injection pipe, a water inlet pipe arranged in the air injection pipe, and a sprayer fixedly connected with the air injection pipe; a water jacket communicated with the water inlet pipe is arranged outside the sprayer in sleeving manner; a plurality of water jetting holes for water to flow out are formed in the axial wall of the water jacket. Wherein, a water jetting control sleeve for controlling water discharge is arranged outside the water jacket in a sleeving manner, the water jetting control sleeve is connected with a pull rod sleeved with a spring; one end of the spring is fixed on the air injection pipe by a spring plate and the other end is placed against the water jetting control sleeve. The method comprises four steps of preparing, forming a low pressure gasification burned out area, cooling the sprayer and finishing the coal underground gasification. The temperature of the burned out area is not reduced excessively while the sprayer is protected, a fresh coal bed is cut completely to form more clearances, the ignition speed can be reduced, the temperature of the burned out area near the sprayer is reduced, the evaporation of water is reduced, and the permeability of underground coal bed is improved.

Description

technical field [0001] The invention relates to the gasification of mined coal, in particular to an underground gasification device and an underground gasification method for mined coal. Background technique [0002] In the process of underground coal gasification, the loose underground coal seam is more conducive to the infiltration of gasification agent and the precipitation of product gas. It has been considered a feasible method to improve the underground gasification efficiency by increasing the cracks in the underground coal seam. In traditional natural gas extraction, fracturing can increase the cracks in underground coal seams, but for thin coal seam roofs with a low degree of metamorphism, high pressure may cause coal seam perforation, and water in the aquifer will flow into the coal seam, which will greatly affect the underground gasification effect; In traditional coalfield mining, perforation and hydraulic punching can also improve the permeability of coal seams ...

AI Technical Summary

Problems solved by technology

In traditional natural gas extraction, fracturing can increase the cracks in underground coal seams, but for thin coal seam roofs with a low degree of metamorphism, high pressure may cause coal seam perforation, and water in the aquifer will flow into the coal seam, which will greatly affect the underground gasification effect; In traditional coalfield mining, perforation and hydraulic punching can also improve the permeability of coal seams in a short distance, but how to use this method can only process all the holes at one time during the horizontal drilling process. It is uncertain whether these short-distance holes will still be fully functional during months of underground gasification.

[0003] Chinese patent 201210489910.1 introduces a method of drilling and anti-permeability under the mine. The permeability of the coal seam is increased by drilling first, and then adopting fracturing and hydraulic slits. However, this method is suitable for underground mining. In underground gasification operation, it is difficult to realize

Hydraulic slotting technology is widely used in coal seam gasification, increasing underground coal seam cracks through water perforation, but this method needs to complete the slotting operation of all underground coal seams at one time, and in the process of underground coal gasification, staged gasification It takes a long time. After a long time, due to the action of the underground coal seam, the coal seam cracks will be closed, which greatly reduces the work efficiency.

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