Gasification furnace underground water prevention and control method and device for underground coal gasification

Abstract

The invention discloses a gasification furnace underground water prevention and control method for underground coal gasification, which comprises the following steps of pumping and draining part of water in an overlying water filling and containing layer on a top plate of an underground coal gasification furnace from a pressure-reducing draining well; and re-injecting drained and discharged water into a water injection layer by a water injection well, wherein the water injection layer and the overlying water filling and containing layer are the same water filling layer or different water filling layers, and after water draining and discharging are carried out on the overlying water filling and containing layer, the underground water level in the pressure-reducing draining well is equal to or greater than a safety design water level of the gasification furnace. The invention also provides a gasification furnace underground water prevention and control device for the underground coal gasification, which comprises the pressure-reducing draining well, the water injection well, a water draining pipeline and a water sucking pump, wherein one end of the water draining pipeline is in the pressure-reducing draining well and extends into the overlying water filling and containing layer, the other end of the water draining pipeline extends into the water injection well, and the water sucking pump can be used for pumping water in the draining water filling and containing layer into the water injecting layer. The method and the device can effectively prevent damage of under ground water on the underground coal gasification.

Description

technical field [0001] The invention relates to a method and device for preventing and controlling groundwater in an underground coal gasification furnace, in particular to a method and device for preventing and controlling groundwater in an underground coal gasification furnace without a well. Background technique [0002] Underground coal gasification is the process of directly burning underground coal in a controlled manner, through the thermal and chemical effects of coal to generate combustible gas, which has the advantages of good safety, low investment, high efficiency, and less pollution. The attention of countries all over the world is known as the second generation coal mining method. However, for wellless underground gasification, the operations that can be performed manually are all on the ground, and it is difficult to directly intervene underground. Because coal is mined underground, for the water-filled aquifer above the coal seam, during the underground coal...

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Problems solved by technology

[0005] 1. In conventional coal mining, it is usually treated by dredging. It is necessary to drain all the groundwater in the water-filled aquifer above the gasified coal seam. Compared with reducing the pressure bearing capacity of the aquifer, the cost is high

[0006] 2. Conventional dehydration mining will completely empty the groundwater in the water-filled aquifer above the coal seam, which will cause surface subsidence and seriously affect ground buildings, transportation, farmland cultivation and irrigation

[0007] 3. Conventional dewatering and drainage will directly discharge the dewatering water. In the case of poor water quality, direct discharge without treatment will cause great pollution to the environment, and if the water quality is treated, the cost will be higher

[0008] 4. "The water-filled aquifer above the coal seam" contains a certain amount of water, which is still necessary for underground coal gasification, because an appropriate amount of water is conducive to the improvement of the quality of coal gas for underground gasification, because water can be used as a The agent participates in the reaction, which is essentially one of the requirements of "water control", but the existing technology can't meet the "water control" requirement by emptying the water

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