一种钻孔水力采煤系统的研究

钻孔水力采煤是指从地表钻孔至煤层借助送至孔底的水射流切割破碎煤层,使之变成具有流动性的煤水混合物。通过水力或气举提升的方法提升到地表并在地表进行煤、水分离的一种采煤方法。文中提出了一种钻孔水力采煤系统的原理、构成及其施工工艺。通过理论分析和试验研究,对该钻孔水力采煤系统的射流泵水力提升、气举提升和水射流破碎的三个关键技术,进行讨论和分析,得出一些有用的结论:(1)为提高采矿效率和单井采煤量并降低能耗,必须将钻孔水力采煤系统的三个关键技术有机地结合起来进行设计。射流泵的设计应该满足煤颗粒最低悬浮速度、无量纲参数的最优化以及防止汽蚀的要求;(2)在射流泵喷嘴形式的选择中,可以根据吸入颗粒的大小来选择中心喷嘴或环形喷嘴射流泵;(3)气举的提升和背压作用可以提高射流泵的提升能力并降低能耗。气举提升单独作为一种开采扬矿工艺具有很大的局限性,但其与射流泵结合后就能很大程度地提高射流泵的提升能力;(4)气举提升与水射流破碎相结合能充分提高水射流的破碎半径和破煤能力。影响水射流效果的主要因素是射流的淹没状态、射流压力和流量,钻孔水力采煤破碎水枪的理想射流是非淹没自由射流,通过气举作用可以在开采峒室内创建非淹没自由射流。

Research on one borehole hydraulic coal mining system

The Borehole Hydraulic Coal Mining System (BHCMS) causes fragmentation of coal seams and removes coal slump through a drilled hole using high-pressured water jet. Then the mixture of coal and water as slurry are driven out of the borehole by hydraulic or air-lifting method and are separated at the surface. This paper presents a case study of hydraulic borehole coal mining. The three key elements, namely, hydraulic lift of jet pump, air lift, and water jet disintegration are discussed and analyzed in this paper based on theoretical analysis and field experiments. Some useful findings have been obtained. The design of jet pump, air lift system, and water jet has to be integrated appropriately in order to improve mining efficiency and coal recovery rate, and to decrease energy consumption. The design of hydraulic lift jet pump must meet the requirement of the minimum floating speed of coal particles. The optimization of nondimensional parameters and prevention of cavitation have to be considered in the design. With regard to selecting the nozzle types of jet pump, center nozzle or annular nozzle can be selected according to the size of the removed particles. Through air-lift and back pressure, the water head can be decreased to improve the lift capacity of jet pump and decrease the power loss. The air lift has great limitation if it is used solely to extract coal, but if it is employed in conjunction with jet pump, the lift capacity of jet pump can be increased greatly. With water jets, the air lift can improve the fragmentation radius and capacity. The main factors that affect the effect of water jet are the submergible status of jet, jet pressure, and flow. The ideal jet of the monitor in the borehole hydraulic coal-mining system is a nonsubmergible free jet. Through air lift, the nonsubmergible free jet can be set up in the mining hole.