文昌气田输气管道排水干燥惰化工艺技术

Drainage,drying and inerting techniques for gas pipelines in Wenchang Gas Field

根据文昌气田外输海底管道在预调试阶段就要求直接干燥至露点温度-42℃的要求,开展了海底管道排水干燥方案的研究,经论证选择了以乙二醇排水干燥工艺为主体,并辅以真空干燥法进行干燥的工艺,在此基础上,建立清管列车,并对其进行了优化设计;排水干燥列车由7个双向直板清管器组成(沿排水方向从前往后为2个淡水段塞、3个乙二醇段塞、2个干空气段塞),经计算,最终确定了排水干燥所需的干燥机、空压机、增压机等设备选型。实际应用表明,由干燥空气驱动的排水干燥清管器列车,可高效一次性完成海底管道的除盐、测径、排水、干燥作业,排水干燥后最终干燥露点温度达-45℃,很好地完成了工程任务。

In the pre-commissioning stage,the export submarine pipeline of Wenchang Gas Field should be directly dried to the dew point temperature of 42℃.On the basis of this requirement,this paper studies the drainage and drying scheme for submarine pipelines.Through augmentation,the drainage and drying process of mono ethylene glycol(MEG)is selected as the principal technique of the scheme,supplemented by the vacuum drying method.On this basis,a pigging train is constructed and optimized.Specifically,the drainage and drying train is composed of seven bidirectional straight-plate pigs(i.e.,two freshwater slugs,three MEG slugs,and two dry air slugs from front to back along the drainage direction).Upon calculation,the models of the dryer,air compressor,booster,and other equipment required for drainage and drying are finally determined.The practical application indicates that the pigging train driven by dry air can efficiently complete the desalting,diameter measurement,drainage,and drying of submarine pipelines at once,and the final dew-point temperature reaches 45℃.Thus,the engineering task is completed.