Impact of structure parameters on shutdown of heat tracing heavy oil pipeline

A two-dimensional transient mathematical model for heat tracing heavy oil pipeline is established to study the impacts of structure parameters, such as the filled medium, thickness of the insulation layer, and emissivity of the coating on the temperature profile in the pipeline when single pipeline shuts down and two pipelines shut down. Safe shutdown durations of different parameters are determined. The simulation results show that when one pipeline shuts down, the temperature drop decreases with the increase of the heat transfer coefficient of the filled medium, and it increases with the decrease of the emissivity of the coating, while the temperature drop first decreases and then increases with the increase of the insulation thickness. When two pipelines shut down, the temperature of the heavy oil in the pipeline decreases linearly with the increase of the shutdown duration. Heat conducting mud and coating can significantly decrease the temperature drop rate and temperature drop range. The optimal thickness of the insulation layer is 60 mm. High emissive coating can prolong the safe shutdown duration.