A Simplified Simulation Model for Buried Hot Oil Pipeline Temperature Field During Shutdown

Abstract

The temperature drop of waxy crude oil after a shutdown is the basic premise for restarting relative mechanical calculation. However, computational accuracy has been paid much more attention excessively in the relevant techniques proposed in the previous researches for this calculation but ignoring the practicability of the calculation results. In this paper a new mathematical model is established for a buried hot crude oil pipeline during shutdown with the simplified complex physical process of oil cooling process reasonably, in which the heat transfer mode of crude oil is divided into pure convection heat transfer and pure heat conduction with stagnation point temperature neglecting the difference of radial temperature. The quasi periodic property theory of soil temperature field is referenced to be as the boundary condition for the thermal influence region. A numerical solution with a structured grid and an analytical solution under polar coordinate are respectively applied for the soil region and other regions including pipe wall, wax layer and insulation layer. The finite volume method is adopted to discretize the heat transfer control equation at the same time the boundary conditions are treated by the additional source term method. The simulation results of the new model are verified by a temperature field tested experiment, especially analyzing the temperature deviation between the simulation and the equivalent mean value of actual oil temperature. At last the effect of buried depth of pipeline on the temperature profiles during normal operation and the temperature drop process of crude oil were investigated based on the simplified model.