Spontaneous combustion prevention gas extraction system and method for goaf

The invention belongs to the technical field of coal mine underground safety prevention and control, and particularly relates to a goaf spontaneous combustion prevention gas extraction system and method.The goaf spontaneous combustion prevention gas extraction system comprises a nitrogen injection system, a gas extraction system and a double-layer sleeve, the double-layer sleeve comprises an inner-layer sleeve and an outer-layer extraction sleeve, the bottom of the inner-layer sleeve extends to a caving zone layer, and the top of the inner-layer sleeve is connected with the nitrogen injection system; nitrogen is injected into the goaf, the nitrogen in the goaf separates gas from oxygen, an isolation belt is formed, the conditions of coal seam spontaneous combustion and gas explosion of the goaf can be reduced, meanwhile, the gas in the goaf can be extracted, and the safety of the goaf is improved. And the effect that one hole has multiple purposes is achieved, the floor area of the ground is reduced, and the