压入式局部通风倾斜巷道掘进工作面瓦斯分布规律

Probing the regularity of the gas distribution in a sloping head-face on the background of forced auxiliary ventilation

运用Fluent软件对压入式局部通风倾斜巷道掘进工作面瓦斯分布进行了模拟。比较了向上掘进和向下掘进巷道中瓦斯分布的不同;分析了风量对向上、向下倾斜掘进巷道中瓦斯分布的影响;研究了消除瓦斯高浓度区域向上、向下倾斜巷道所需风量的差别。结果表明:当条件相同,即风筒出口平均风速、倾斜角度和迎头瓦斯涌出量相同时,向上倾斜掘进工作面的高浓度瓦斯区域比向下倾斜时的高浓度瓦斯区域大;当回风流中瓦斯平均浓度不变时,随着风量和瓦斯涌出量的增加,由于风量的增加使到达迎头的风速变大,使空气和瓦斯混合得更加均匀,向上倾斜掘进工作面的高浓度瓦斯区域和向下倾斜的高浓度瓦斯区域之间的差距逐渐减小。消除高浓度瓦斯区域所需的风筒出口风量向上倾斜掘进巷道比向下倾斜掘进巷道大。

The present paper takes its target to simulate the gas distribution in sloping heading face with forced auxiliary ventilation by using a market-available software named Fluent. Our simulation results can be compared between the upward and downward heading faces with the forced auxiliary ventilation going on. In proceeding with our research, we have analyzed the influence of ventilation airflow quantity on the methane distribution. Since the airflow quantity is needed to guarantee the elimination of the methane collection in the upward and downward heading faces, detailed analysis should be done of the average methane concentration in the mining faces. The results of our analysis indicate that under the same condition, when the average exporting velocity of the duct, the angle of inclination and the gas emission amount in face should be made in correspondence with each other. If the average methane concentration in return airflow is lower, there should exist a range of high-concentration methane area in the sloping face. The problem is actually caused by the gas buoyancy. However, when the gas is filled in the upward heading face, there would appear accumulation of the gas at the top of the heading face,which makes the gas difficult to be eliminated. Thus,the zone with high-concentrated gas would be larger in the downward face due to the convection. In such a situation, the airflow and the gas flow would be fully mixed and make the high concentration gas zone smaller than that in the upward face. However, the difference in the zone with high concentrated methane is likely to get smaller with the increase of the air quantity and methane emission rate, if the average methane concentration in the return airflow is the same with the exporting airflow, which is caused by the increase of the airflow in the upward face and the mixture of air and gas there turns to be more evenly. However, when the zone with high concentrated methane in upward heading face remains larger than that in downward face, the angle of inclination and the gas emission in sloping heading face would also remain the same. And, in turn, the airflow quantity needed to eliminate the methane collection should be much bigger at the upward face than at the downward face.