输气管道线路截断阀压降速率设定值研究

Study on Pressure Drop Rate Set Value of Block Valve in Gas Pipeline

天然气长输管道间隔一定距离需设置线路截断阀,以便在破损事故发生时快速截断气源,避免产生更大的泄漏。对大口径输气管道,线路截断阀的主要启动判别方法为压降速率法。目前,西气东输工程等大管径输气管道线路截断阀压降速率设定值通常为0.15 MPa/min。实际上,对于不同口径以及不同工况下运行的天然气长输管道而言,管道全线采用一个统一的经验值具有很大的不确定性,往往会发生线路截断阀的误动作或事故状态下不动作或未及时动作的情况。以某工程两座压气站之间的管段为例,利用OLGA软件对不同工况下管内气体流动进行动态模拟,研究了破口尺寸、主管管径、运行压力、破口位置、输量等不同参数对管道压降速率的影响,为目前采用的压降速率设定值是否需要修正提供参考,使其更符合工程实际。

Intermediate block valve shall be installed in order to reduce leakage in case of a pipeline rupture.For large-diameter gas pipeline,main startup distinguishing method of the block valve is called as Pressure-Drop Rate method.At present,the common set value of pressure-drop rate for such large-diameter pipeline as West-to-East Gas Pipeline is 0.15 MPa/min.However,it will bring about such some problems as malfunction,act delay and refusal if the set value for all long-distance pipelines with different diameters and operating conditions are the same.Hence,it is very important to study the set valve of intermediate block valves in practical works.OLGA software is applied to conduct dynamic simulation of a pipeline segment between two compressor stations of some gas pipeline and studied is the effect of such parameters as rupture size,diameter,operating pressure,rupture location and flow rate on pipeline pressure drop rate,which can provide valuable reference for set value determination and modification.