热油管道停输数值模拟

合理进行热油管道停输后的温度计算，模拟原油的凝固过程，有利于热油管道安全停输时间和再启动方案的确定。针对加热原油管道停输后油品物性、管道及周围介质的相互关系及其不稳定传热问题，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处理，构造出问题的差分方程。运用所提出的方法，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的计算方法相比，计算结果更符合实际情况。

Numerical Analysis of Heated Crude Oil Pipeline at Shutdown

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