The Reserch On Shutdown And Restart Of Qingwei Crude Oil Pipeline

The reasons of pipeline was forced to shut down, on the one hand, due to the pipeline planned maintenance, operator error, third-party damage or cause of the accident; On the other hand, with the continuous decrease of non-renewable energy, also can appear shortage or lack of supply of crude oil, crude oil supply can’t satisfy the throughput of pipeline, makes the waste heat consumption and increase operation instability, finally forced to batch delivery. The thermal, hydraulic condition and the change of surrounding environment during the pipeline transportation, which has an impact on the restart after shut down, so it is necessary to study on the thermal and hydraulic of the crude pipeline’s restart after shutdown.In order to make the buried crude oil pipeline operating safely and economically, based on the steady state operation of crude oil pipeline, the non-steady state temperature field, temperature changes after shutdown, temperature and pressure parameters etc. after restart are simulated and analyzed, the optimized shutdown, boot program is put forward. This paper mainly discusses the following aspects:Firstly, the soil temperature field around the pipeline under different operation conditions of the pipeline was numerically simulated by using ANSYS software and the finite element method.Secondly, considering the effect of friction heat, latent heat of solidification, crude oil physical property parameters etc. the oil pipeline are divided into sections, and the heat and hydraulic model of the pipeline on steady-state conditions are established, which can be used to solve exactly temperature drop and pressure drop of the buried oil pipeline at an arbitrary cross-section.Thirdly, the mathematical model of the natural soil temperature field,the physical and mathematical model of hot oil pipeline soil temperature field under non-steady state are built, therefore according to the different characteristics of nodes,the mathematical method and meta-body balance method are used to derive the various nodes of finite difference equations.Fourthly, with Qingwei diesel pipeline as an example, through numerical simulation, using software SPS(the full name is stoner pipeline simulator) to simulate the process of temperature drop after shutdown, the restart pressure needed, peak pressure and maximum safe shutdown time.Fifthly, based on determining the temperature of the safe transportation, the custody transfer process optimization study is carried out on each station of Qingwei pipeline. The results show that the custody transfer process has many advantage on both energy saving and economic aspect, thus it is necessary to carry out the process of the transformation of the closed pipeline transport.