煤层气井负压射流快速排煤粉装置研究

Study of coal particles vacuuming cleanout jet pump in coalbed methane wells

针对煤粉颗粒沉积在煤层气井底部导致埋泵等问题,提出利用射流泵的负压吸附原理和双层同心管柱结构,设计的负压射流快速排煤粉装置,能够快速清除井底煤粉.基于射流泵理论和能量守恒定律,采用洛伦兹混合损失模型,推导出该排煤粉装置的基本性能方程,并综合举升最小压力比,气蚀最大流量比以及效率最优面积比3种约束条件,对装置的具体性能进行了研究.研究结果表明:井深1 000m以上的煤层气井要求举升最小压力比达到0.75以上;面积比和动力液压力越小,井底压力越大,气蚀最大流量比就越大;效率最优面积比为0.27,面积比越大最优流量比越小.最后根据不同井况,在给定动力液压力和流量条件下,设计了喷嘴和喉管尺寸组合.

Once solid particles, like coal particles, settles down in the coalbed methane well, it will cause stuck pump and other serious consequences. As for this problem, this study uses the negative-pressure adsorption theory and concentric dual tubes to design a novel apparatus of clean-out of coal dust in the use of negative-pressure jet. This apparatus can quickly clean out the coal dust in the underground coal mine. Based on the jet pump theory and energy conserva- tion law, the use of Lorenz Mixed Loss Model infers the basic performance equation of this ap- paratus used in coal dust. Further, the study investigates the concrete performance of appara- tus using the lift minimum pressure ratio, the cavitation maximum flow rate ratio and the opti- mum area ratio. The results show that the lift minimum pressure ratio should be no less than 0. 75 if the depth of CBM well is more than 1 000 m; the smaller the area ratio and power fluid pressure are, the higher the pressure at the bottom of well is, and the higher the cavitation maximum flow rate ratio; the optimum area ratio of efficiency is 0.27, and the higher the area ratio is, the smaller the optimal flow ratio is. At last, for the given power fluid pressure and flow rate, this study designs the series of dimensions for jet nozzles and throat pipes that suit for different CBM wells conditions.