采空区注超临界CO2防灭火试验研究

为研究超临界CO₂注入采空区防灭火的规律，自主研制了产生超临界CO₂和模拟采空区遗煤自燃升温试验系统，得到了不同温压条件下超临界CO₂注入采空区前后不同监测点的温度、O₂和CO浓度变化数据信息。试验结果表明:注入采空区的超临界CO₂发生相变，有序结构急速失序，大量吸收热量，采空区内的煤体、空气温度随时间呈线性快速下降规律，其降温能力是气态N₂的10倍；超临界CO₂在自燃发火煤体中的强渗透扩散特性，使自燃煤体快速惰化，防灭火效率高；停止注入后，小范围回温符合反二次函数特征；高压力超临界CO₂相对于低压条件，防灭火性能更佳；超临界CO₂是1种降温降氧能力显著，且输送性能优良的采空区新型防灭火材料，超临界CO₂防灭火效果优于气态N₂。

Experimental study on injecting supercritical CO2 into goaf for fire prevention and extinguishment

To reveal the fire prevention and extinguishment laws by injecting supercritical CO₂ into the goaf, an experimental system for producing supercritical CO₂ and simulating the spontaneous combustion of residual coal in goaf was developed independently. The data of temperature, oxygen concentration and CO concentration variation at different monitoring points before and after injecting supercritical CO₂ into goaf under different temperature and pressure conditions were obtained. The results showed that the supercritical CO₂ injected into the goaf occurred the phase transition, the ordered structure disordered rapidly, a large amount of heat was absorbed, and the temperature of coal and air in the goaf presented the linearly rapid decline with time, whose cooling ability was 10 times that of gaseous nitrogen. The strong permeability and diffusion characteristics of supercritical CO₂ in the coal with spontaneous combustion made the coal inert quickly, with the high efficiency of fire prevention and extinguishment. After stopping the injection, the rebound temperature in a small range conformed to the feature of inverse quadratic function. The high pressure supercritical CO₂ had better fire prevention and extinguishment performance compared with the low pressure condition. The supercritical CO₂ is a new material for fire prevention and extinguishment in goaf with significant cooling and oxygen reducing abilities and excellent transportation performance, with the better fire prevention and extinguishment effect than the gaseous nitrogen.