井下液态CO2爆破增透工业试验研究

为了增加煤层透气性、提高瓦斯抽采效率，选取七台河矿区进行液态CO2爆破煤层增透工业试验。研究液态CO2爆破过程中主管内高压气体P-T曲线，考察不同地应力下的液态CO2爆破有效影响半径和煤层透气性系数，监测爆破前后瓦斯抽采参数。试验结果表明:采用压缩气体与水蒸气容器爆破方法计算液态CO2爆破的当量为180 gTNT；爆破后瓦斯抽采浓度提高3.16倍，瓦斯抽采混合流量提高1.71倍；煤层液态CO2爆破有效影响半径随地应力的增加近线性减小，随爆破压力的增加非线性增加，确定液态CO2爆破时最佳爆破压力范围160~280 MPa；爆破前后对比，煤层透气性系数提升17.49~22.76倍。井下煤层液态CO2爆破技术的实施，有助于降低爆破成本、提高增透效果和瓦斯抽采利用率。

Industry experimental research on improving permeability by underground liquid CO2 blasting

In order to improve coal seam permeability and gas extraction efficiency, the industry experiments on improving coal seam permeability by liquid CO2 blasting were conducted in Qitaihe mine area. The P-T curves of high-pressure gas in the main pipe during the liquid CO2 blasting process were studied, then the effective influencing radius of blasting and the gas permeability coefficient of coal seam under different ground stresses were investigated, and the gas extraction parameters before and after the blasting were monitored. The results showed that the TNT equivalent of liquid CO2 blasting was 180 g calculated by the computational model of compressed air and steam vessel explosion. The gas extraction concentration increased by 3.16 times and extraction mixed flow rate increased by 1.71 times after blasting. The effective influencing radius of liquid CO2 blasting in coal seam decreased linearly with the increase of ground stress, and increased nonlinearly with the increase of blasting pressure. The best range of blasting pressure was determined as 160-280MPa. The gas permeability coefficient of coal seam increased by 17.49-22.76 times after blasting. The implementation of underground liquid CO2 blasting in coal seam helps to reduce blasting cost and increase the improving permeability effect and gas utilization ratio.