Simulation Analysis of Safe Shutdown and Restart Procedure in Oil Transportation Pipeline

It is inevitable to be shutdown and restart during the operation of the hot oil pipeline. The oil temperature in the pipe will decrease and the viscosity will increases after shutdown. When the oil temperature reaches a certain extent, the restart process will be difficult, and sometimes will even fail, which will cause serious economic loss and environmental pollution. In order to avoid this kind of accident, it is demand to analyze and calculate the rule of crude oil temperature-drop, the safe shutdown time and the restart pressure of the pipeline accurately. Base on the hydraulic and thermal analysis, this paper establishes the unsteady hydraulic and thermal models for shutdown and restart of the crude oil pipeline. Take the actual operating condition of Qing-Ha buried oil pipeline as an example, this paper applies numerical simulation method to simulate and analyze the rule of crude oil temperature drop after shutdown, the oil temperature distribution along the line and the pressure change in the pipeline when restart, and gets the discriminance of successful restart and restart time for the pipeline. All of above are significant for the safe operation of the pipeline.