加热原油管道停输热力计算

在加热原油管道停输过程中 ,油品温度下降 ,粘度上升 ,有时甚至出现冻管事故 ,常常给再启动带来困难。合理地进行热油管道停输后的温度计算 ,模拟原油的凝固过程 ,有利于确定安全停输时间 ,制订再启动方案。针对加热原油管道停输后油品、管道及周围介质的相互关系和它们的不稳定传热 ,提出了热力计算的数学模型。该模型综合考虑了有关物性参数随温度的变化以及在冷却过程中油品的凝固问题。采用保角变换和盒式积分法对数学模型进行了处理 ,并构造出问题的差分方程。通过数值计算分析管道停输后油品冷却和冷凝规律 ,运用文中所提出的方法 ,对加热原油管道停输温度变化和冷凝过程进行了计算 ,与实测数据和文献中计算方法相比 ,该计算结果更符合实际情况

FHERMAL CALCULATION OF HEATED CRUDE OIL PIPELINE AT SHUTDOW

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.