空气动力掏煤工艺之压风排水排渣关键技术

基于谢一矿地面钻井空气动力掏煤压风吹水吹渣工程实践,通过分析环空内气体携水携渣机制、吹水作业单次下钻深度,对压风排水排渣关键技术进行了研究。首次确定了套管段吹水作业单次下钻深度、吹水时间等策略;提出了煤层段是否含水条件下的吹水吹渣技术,包括下钻接单根速度要快,开始下行前须先实现压风洗井循环,并使钻柱保持旋转状态,且下行速度宜缓,以及针对固结干煤粉的定点强吹法等技术要点;理清了环空“架桥”、钻杆“倒吸”堵塞发生机制及处理对策,认为在洞穴内有水条件下,下钻前不实现压风洗井循环,是导致环空“架桥”堵塞的主因,而起钻使钻头位置高于堵塞部位,再压风洗井即可解堵;钻杆“倒吸”堵塞则是由于其在井口放气过快导致的,关闭放气阀,或放气减速,即可预防;探究了空气动力造穴高压放喷排渣机制和技术,认为,高压下放喷,环空中压降大,固气混合流体上返流速快,返排效果好;钻杆下入洞穴内的顶部和中低部相比,后者条件下煤粉上返量更多;对放喷后大块率增加的垮塌煤体可采用旋转钻头碾压破碎、定点强吹实现目标。

Key techniques of gas injection,water drainage and slag discharge in aerodynamic excavating coal process

Based on the engineering practice of surface well drilling for aerodynamic excavating coal using compressed air to blow water and slag in Xieyi Mine,the key technologies of water drainage and slag discharge by pressurized air were studied by analyzing the mechanism of carrying water and slag by compressed air in the annulus pipe and then deriving the formula to calculate the single drill depth during the blowing water operation.The control technology for blowing water operation in the casing section,such as single drill depth and time to blow water,was determined for the first time.The methods for water and slag discharge in the coal seam with or without water in the cave were also proposed.The key points include making a connection rapidly,flushing cycle with pressurized air before walking down,keeping drill string rotating,slow drilling velocity,and the fixed point blowing method with strong air for the dry pulverized coal consolidated,etc.The plugging mechanisms for annulus “bridging” and drill pipes “reverse inhaling” and the corresponding countermeasures were investigated.The results suggest that the main reason for annulus “bridging” clogging is the missing of flushing cycle with pressurized air before drilling down when there is water in cave,which can be resolved by lifting the bit above the blocked area and then flushing with pressurized air and that the clogging by drill pipe “reverse inhaling” could be prevented by closing or turning down the purge valve because it is caused by the fast venting.In addition,the mechanism and technology for aerodynamic excavating method to discharge slag with high-pressure air injection were investigated.The results demonstrat that the large pressure drop within annulus and quick output of solid-gas mixture occurre along injection with high-pressure air and lead to good flow-back result;the larger output of pulverized coal is achieved when drill pipe is set at the middle or bottom of the cave,rather than the top part;and the collapsed coal with large blocks after air injection could be crushed with rotating bit and then be blown out using the fixed point blowing method with strong air.