Congelation Risk Assessment Of Oil Pipeline And Determination Of Safe Shutdown Time

This paper was financially supported by National Natural Science Foundation of China(No.51106020, No.51174042, No.51051002), PetroChina Innovation Foundation(2012D-5006-0610) and Youth Scholar Backbone Supporting Plan Project of HeilongjiangGeneral Colleges and Universities (1252G005).Congelation accident in pipeline of crude oil is a serious problem in china, which ismainly determined by the properties of domestic crude oil such as high wax content, highpour point and viscosity. When oil pipeline operates at low throughput or shutdown,congelation accident always happen as the temperature of oil drops, which causes malignantaccidents and significant financial losses. Therefore, it is necessary to conduct congelationrisk assessmen of oil transportation pipeline, calculate and determine a more reasonable safetyshutdown time, which can provide evidences for accident treatment, planned maintenance,security operation and scientific management. Firstly, according to the statistics and analysisof congelation accident, the various reasons of affecting pipeline congelation failure weredetermined. Combining with fuzzy comprehensive assessment method, the related importanceof factors on congelation accident was studied, and the grade of factors affecting failurecongelation of pipeline was also identified. Secondly, using improved Monte-Carlo method ofreliability theory, the failure possibility of congelation was numerically calculated and somecorresponding improvement measures were put forward. Besides, the consequences ofcongelation accident were fully analyzed, and then various losses were also caculated. Finally,on the basis of determining the congelation failure possibility of the restart pressure,combining pipeline safety shutdown time with the congelation failure possibility, a morereasonable and meaningful calculation method of safety shutdown time was obtioned. Thecalculation program was compiled to determine safety shotdown time with Turbo C2.0language, and an example calculation was conducted, the main factors of safety shutdowntime were also discussed.