Closed-loop system and method for intensified extraction of heat injection coal seam after combustion of underground coal mine gas

Abstract

The invention discloses a closed-loop system and method for intensified extraction of a hot coal seam after combustion of underground coal mine gas, and is suitable for coal mine gas extraction. Comprising a gas supply system, a heat injection system and a mixed gas generator, the gas supply system is connected with the input end of the mixed gas generator, and the heat injection system is connected with an output system of the mixed gas generator; a mixed gas generator is arranged under a coal mine, extracted gas serves as fuel to be combusted to generate tail gas, the tail gas exchanges heat with water to generate water vapor, the tail gas and the water vapor are injected into a coal seam, gas desorption in the coal seam is achieved, and seepage migration is conducted under the pressure effect; high-temperature and high-pressure fracturing forms a fracture network in the coal seam to improve gas extraction, all the steps form closed forward cyclic utilization, gas is converted into CO2, the risk of coal and gas outburst is reduced or eliminated, and the influence on the atmospheric greenhouse effect is reduced.

Description

technical field [0001] The invention relates to a closed-loop system and method for intensified drainage of coal seams, and is especially suitable for a closed-loop system and method for intensified drainage of coal seams by injecting heat into coal seams after underground gas is burned in coal mines and used for gas drainage in coal mines. Background technique [0002] At present, the commonly used gas drainage methods mainly include: hydraulic fracturing, deep hole blasting, hydraulic slitting, and protection layer mining. However, there are some defects in the application of these technologies. The channel for migration; it is difficult to deliver medicine in deep hole blasting; the application effect of hydraulic slotting in soft coal seams is poor, and due to the problem of slag discharge, it is not suitable for drilling downwards; mining of protective layers is not suitable for mining in a single coal seam. Therefore, it is particularly important to develop a coal seam...

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Problems solved by technology

Some scholars have studied the effect of temperature on gas adsorption and desorption, and believe that the increase of temperature can significantly promote gas desorption, and the thermal stress induced by temperature is conducive to the generation of coal seam pores and cracks. Because of the existence of gas in underground coal mines, the requirements for explosion protection are particularly high. So far, there is no high-temperature gas generator suitable for downhole operations; the way of generating high-temperature gas from the ground to the downhole through pipelines is too long, the cost is high, and the heat loss along the way is large, so it has not been used so far.

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