Study On Safe Shutdown Time And Restart Process Of Waxy Crude Oil Heating Transport Pipeline

In this era of rapid development of the global economy,our demand for oil is increasing day by day,so safe and efficient pipeline transportation is gradually being widely used.Among the many types of pipelines,underwater pipelines and overhead pipelines are generally influenced by geographical factors,and are generally used exclusively for special purposes.Buried pipelines have many advantages and are widely used.Due to planned pipeline maintenance,natural disasters,lack of resources,and various human factors,the pipeline was forced to stop.During the shutdown,the thermal and hydraulic power of the pipeline changed,affecting whether the pipeline can be restarted.Study on the safe shutdown time and restart process of buried hot oil pipeline.In order to more accurately analyze and summarize the changes of relevant parameters during the pipeline shutdown and restart process,this paper uses the simulation software to simulate the relevant steady-state operating conditions and thermal shutdown models based on the conclusions of previous theoretical calculations.And the thermal and hydraulic simulation of the restart model.The investigation was mainly carried out from the following aspects:(1)The mathematical model of heat transfer in the steady-state working condition of the buried hot oil pipeline was established,and the temperature drop along the way was calculated in sections using the specific heat capacity.(2)The mathematical model of the buried hot oil pipeline's shutdown condition was established,and the model was solved using the element balance method to obtain the basic formula of the pipeline's safe shutdown time.Fluent simulation software was used to simulate the influence of relevant factors on the temperature drop law of pipeline shutdown.(3)The mathematical model of thermo-hydraulic coupling under restart conditions was established.The shock wave theory and the double characteristic line method are used for solution.(4)Fluent simulation software was used to simulate the different working conditions of a buried hot oil transportation pipeline,and the law of temperature drop during shutdown,the surrounding soil temperature field and the temperature change along the pipeline and the pressure change at the station inlet during restart were analyzed.