Abstract:

During the period of shut - down of a heated crude oil pipeline, the temperature drop of oil will make its viscosity rise and even result in the frozen pipeline, it will cause difficulty for restart of pipeline. The accurate temperature computation and solidifying simulation of oil in the pipeline are therefore essential both for estimating maximum allowable solidifying time of shut down and making restarting strategy of pipeline. In the light of the interaction of oil, pipeline and ambient media and their unstable heat transmission, considering temperature dependent on physical properties and phase change of oil, a mathematical model for thermal calculation is presented. By conformal transformation and cassette integration, this model can be used to do a series of numerical calculations, and analyze the cooling and solidifying law of the oil upon shutdown. As examples, the oil temperature change and solidifying process were calculated by this method, and satisfactory results have been obtained. Comparing this method with the others introduced in references and the measured results indicate that the model and algorithm derived here are more reliable.

Key words: pipeline, heating transportation, thermal calculation, temperature distribution, mathematical model