煤层气集输管道持液率影响因素及排液点优选

煤层气开采压力低、产量小,且常含有大量液态水,集输管道上坡段容易产生管道积液,使得摩阻增大并出现段塞流,引起压力骤降,不利于集输管道安全运行。本文利用模拟软件OLGA分析入口流量、管径、气液比和出口压力对煤层气集输管道持液率的影响,得到了煤层气集输管道各管段持液率分布规律,并进一步比较了基于管道持液率、流型、压降和排液点个数的4种排液点设置方案。结果表明,煤层气集输管道压力骤降段均出现在上坡段,出口压力对管道持液率影响最为显著,入口流量和气液比对管道持液率影响规律相似,不同管径下管道持液率在流动方向上的分布也具有一定的相似性;设置排液点后,管道持液率明显下降,管道积液情况得到改善,且方案比较表明,当排液点设置在管段低洼处时,管道持液率最低,且各管段均无段塞流出现,管道压降最小。

Coalbed methane gathering pipeline liquid holdup analysis and discharge point optimization

Because of the low pressure and small production of coalbed methane(CBM) and often containing a lot of liquid water in it, when CBM is transported through pipeline, it is possible that liquid accumulation occurs especially in the upslope sections of pipeline, causing increased friction, slug flow, and pressure drop, which is a threat to the safe operation of the pipeline. In this paper, the simulation software OLGA is used to analyse the effects of the inlet flow rate, pipe diameter, gas-liquid ratio and outlet pressure on the liquid holdup of the CBM gathering pipeline are analyzed and the liquid holdup distribution of the CBM gathering pipeline is obtained. Further, four schemes are compared based on the liquid holdup, flow pattern, pressure drop and the number of drainage points. The results show that the pressure drop appears in the upslope sections of pipeline, and the outlet pressure of CBM gathering pipeline has the most significant influence on the liquid holdup. The effects of inlet flow rate and gasliquid ratio on the liquid holdup are similar, and the distributions of the liquid holdup in the flow direction under different pipe diameters are also similar. Additionally, after setting drainage points, the liquid holdup of the pipeline decreases apparently, and the liquid accumulation of the pipeline is improved. The scheme comparison shows that the liquid holdup is the lowest when the drainage point is set at the lower part of the pipeline with no slug flow and the minimum pressure drop.