Dry ice explosion and air-permeability-enhancing device and method for drawing out gas by using same

Abstract

The invention relates to a dry ice explosion and air-permeability-enhancing device for a low-air-permeability coal seam and a method for drawing out gas by using the dry ice explosion and air-permeability-enhancing device. The dry ice explosion and air-permeability-enhancing device is characterized in that an explosion initiation device consists of an explosion initiator arranged outside a drill hole, a lead arranged in the drill hole and a detonator connected with the lead; a heat-insulating storage device consists of a dry ice storage chamber arranged in a coal body, an inner housing arranged outside the dry ice storage chamber, a first vacuum chamber arranged outside the inner housing, an outer housing arranged outside the first vacuum chamber, a sealed male thread connected with the dry ice storage chamber and a conveying rod, a sealed female thread connected with the sealed male thread and a detonator cavity connected with the sealed female thread; a hole sealing device consists of polyurethane arranged in the drill hole; the explosion initiation device utilizes gas formed by heat-absorbing sublimation of the dry ice to generate high pressure in a limited and sealed space to cause a physical explosion to damage the inner housing of the heat-insulating storage chamber, and the coal body is damaged by shock waves generated by the explosion, so that a channel is provided for gas transportation, the air permeability of the coal seam is improved, the gas drainage ratio is increased, and safety is guaranteed.

Description

Technical field [0001] The invention belongs to the technical field of coal mine gas drainage, and in particular relates to a dry ice explosion anti-reflection device for low-permeability coal seams and a method for draining gas. Background technique [0002] Most of the coal mines in my country are coal and gas outburst mines. As coal production increases and mines extend to the depths, coal and gas outburst mines are gradually increasing. Coal and gas outburst problems have become the main factors affecting safe production. At present, the measures to prevent gas accidents mainly include mining protective layer and pre-draining coal seam gas. Since most of the mineable coal seams are outburst coal seams, pre-draining coal seam gas has become the only measure to control gas. For coal seams with better gas permeability, The gas drainage rate is high, which can effectively achieve the expected purpose. However, for coal seams with low air permeability, only drilling and drainage c...

AI Technical Summary

Problems solved by technology

At present, the measures to prevent and control gas accidents mainly include the mining of protective layers and pre-pumping coal seam gas. Since the minable coal seams of most coal mines are outburst coal seams, pre-pumping coal seam gas is the only measure to control gas. For coal seams with good air permeability, The gas drainage rate is high, which can effectively achieve the expected purpose, but for coal seams with low air permeability, drilling drainage alone cannot meet the needs of the current coal mine safety situation

Nowadays, although there are also methods of "hydraulicization" to enhance gas drainage, such as "hydraulic slotting", "hydraulic punching", "hydraulic fracturing" and "water jet slotting", etc. The infiltration of the coal body is not conducive to gas desorption and drainage, and the gas flow channel is blocked due to the failure of the borehole to drain in time, resulting in a low gas drainage rate

Using the pressure generated by the expansion of compressed gas to destroy the coal body and form cracks can provide an effective channel for gas seepage, and finally achieve the purpose of improving the gas drainage rate, while avoiding the inhibition of water on the flow of gas. For underground use of compressed gas to strengthen gas N injection in the coal seam 2 , the technique mainly utilizes N 2 Strong adsorption to displace gas, but the system equipment is too large to realize continuous N injection 2 ; using CO 2 Phase change fracturing technology, through the heating device, the liquid CO 2 Gasification, injecting impact coal from the small hole to achieve anti-reflection, but the cost of the system is relatively high, especially the heating device is a sensitive component, which greatly reduces the reliability of the system

In addition, although "deep hole pre-splitting blasting" is a relatively effective method of increasing penetration, it is prone to "dummy gun" phenomenon during the implementation process, which seriously threatens the safe production of coal mines

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