为确定电厂烟道气用于遗煤自燃预防的含氧量参数,以塔山坑口电厂及塔山煤矿8105工作面为原型,建立基于计算流体力学(CFD)和煤氧复合理论的遗煤自燃三维数值模型。采用数值模拟方法,研究多场耦合条件下,含氧量为3%9%的烟道气注入采空区后的运移状态以及氧浓度场和温度场的变化规律。结果表明,注入烟道气能够有效惰化采空区遗煤,随注入烟道气含氧量降低,氧化带最大宽度的减小符合Boltzmann函数曲线,同时,遗煤最高温度呈指数下降趋势。降低烟道气含氧量有助于提升遗煤惰化水平,以实测注氮后采空区氧化带宽度为指标,确定7.08%为烟道气用于预防采空区遗煤自燃的合理含氧量上限。
In order to determine the reasonable oxygen content in flue gas for preventing spontaneous combustion of residual coal in gob, a 3D numerical model, based on Computational Fluid Dynamics (CFD) and theory of coal-oxygen reaction, was built to simulate the residual coal's spontaneous combustion in top coal caving gob area in panel 8105 of Tashan Coal Mine. The migration of flue gas in gob, distribution of "three zones" of spontaneous combustion and temperature field with 3%-9% of O2 content in flue gas were analyzed by numerical simulation. The results show that the injected flue gas can inert spontaneous combustion of the residual coal effectively. Along with decrease of oxygen content in the flue gas injected, the maximum width of the oxidation zone will decrease accordingly which is agreed with the curve of Bohzmann function and the maximum temperature of the residual coal will decrease exponentially. Lowering oxygen content in flue gas will improve the inerting effect of the residual coal. Based on the field measured data of the width of oxidation zone after nitrogen was injected, oxygen content is determined to be 7.08% as the reasonable upper limit in the flue gas for preventing spontaneous combustion of residual coal in gob.