榆济输气管道水合物冰堵防治措施

Prevention measures for hydrate ice blockage in Yu-Ji Gas Pipeline

为保障榆济输气管道冬季安全稳定运行,避免出现严重的冰堵事故而影响输气任务的完成及管道安全,亟需理清榆济输气管道气源气质及其所处高寒地区的实际情况,提出安全、经济、高效的水合物冰堵防治措施。基于热力学相平衡理论,应用Chen-Guo模型预测水合物形成条件,采用管输天然气含水量/水露点计算方法分析气源气质含水状况;结合榆济输气管道干线运行工况,判断确定了全线易于析出游离水的管段,建议在夏季对这些管段集中清管排污,并给出防治水合物形成的最小注醇量;针对榆济输气管道分输站场电伴热功率有限的情况,根据分输供气压力和天然气含水量,计算天然气达到含水临界饱和时的水露点温度,从而给出各分输站场需采取注醇措施的极限温度;严格控制气源气质水露点指标,是切断输气管道内游离水来源的关键,也是防治榆济输气管道干线和分输站场水合物冰堵最直接有效的措施。

In order to ensure the safe and stable operation of Yu-Ji Gas Pipeline in winter and avoid serious ice blockage that would affect gas transmission and pipeline safety, it is necessary to sort out gas source quality of Yu-Ji Gas Pipeline and the actual condition of alpine region, and work out safe, economic and effective measures to prevent hydrate ice blockage. Base on the thermodynamic phase equilibrium theory, the conditions of hydrate formation are predicted by Chen-Guo model, and the water content of gas source is analyzed by calculation method of water content and water dew point of pipeline gas. According to operation conditions of Yu-Ji gas trunk line, the sections likely to precipitate free water are identified. Pigging and sewage disposal in summer at these sections are suggested and the minimum methanol injection for prevention and treatment of hydrate formation is given. In view of the limitation of electric heat tracing power in gas offtake stations of Yu-Ji Gas Pipeline, the water dew point of natural gas at the state of critical water saturation is calculated according to the supply pressure and water cut of natural gas, thereby the lower-limit temperature of injecting methanol in each gas offtake station is determined. Strictly control the water dew point of gas source is the key to cut off the source of free water in gas pipeline, also the most direct and effective measure to prevent hydrate blockage in Yu-Ji Gas Pipeline and gas offtake stations. （5 Figures, 1 Table, 11 References）