Causes and treatment measures against ice blockage in Dalian-Shenyang Gas Pipeline

Under the extreme cold in winter in northeastern China, ice blockage accident is very likely to happen in gas pipelines during operation. Dalian-Shenyang Gas Pipeline undertakes the task of LNG export from Dalian, and ice blockage has happened many times after the pipeline's commissioning at the end of 2011. So, this paper analyzes and points out the cause of ice blockage in Dalian-Shenyang Gas Pipeline from aspects of climate, geography, gas source and principle of ice blockage. The cause is that during the process of commissioning, the left water gathered in the low positon places of pipeline, and under the combined effects of low temperature in winter and high pressure inside pipeline, hydrate formed to block the pipeline. Based on the analysis of the applicable conditions and advantages and disadvantages of alcohol injection, heat tracing and pressure reducing, according to the features of low dose highly efficient inhibitor, it is concluded that highly efficient inhibitor can effectively decrease the forming temperature of hydrate in Dalian-Shenyang Gas Pipeline and delay the forming of hydrate. Thus, it can provide a reference to the precaution work of ice blockage in gas pipeline.