关键词: 管道, 顺序输送, 轴向有效分散系数, 混油, 数学模型, 影响因素

Abstract: Density and viscosity differences between adjacent miscible products are the important factors affecting the contamination formed in the undulate multi-product pipeline.The effects of dendity and viscosity differences on contamination process were analyzed.The virtual axial dispersion coefficient related with mass distribution in mixing section was determined.A mathematical model of contamination caused by elevation difference in batching transportation was proposed.In turbulent flow,the influence of oil viscosity on formation of flowing velocity profile was not obvious in the core of oil flow.The change of flowing velocity profile resulted from the density difference had some effect on virtual axial dispersion coefficient.So the model was simplified without consideration of the viscosity variation,and an equation for contamination concentration distribution caused by elevation difference was developed.The factors affecting contamination,such as Reynolds number,pipeline length and inclination angle,were analyzed by means of several examples.The computation results showed that the effect of inclination angle on contamination decreased gradually with the increase of pipeline length and Reynolds number.Particularly,the degree of effect became invisible when pipeline was in completely turbulent flow,and Reynolds number was greater than critical Reynolds number while the pipeline was considerably long.

Key words: pipeline, batching transportation, virtual axial dispersion coefficient, contamination, mathematical model, influencing factor