Study On Two-phase Flow Characteristics Of Diesel Oil Carrying Water

In the process of operation of domestic product pipelines,internal corrosion caused by low-lying stagnant water after production have been found.Internal corrosion in product pipeline will reduce the effective lifetime of pipe,the throughput capacity and the safety of operation.In this paper,the characteristics of oil carrying water are studied through loop experiment and numerical simulation in the case of low-lying stagnant water in pipeline.Effective solutions to product pipeline stagnant water are proposed.In this paper,the basic theory of oil-water two-phase flow,flow patterns,flow pattern identification and calculation models are investigated.The calculation models of oil-water two-phase flow in the upward inclined pipeline is derived by introducing gravity influence.The main influencing factors in the pipeline are velocity,inclination angle,water content and diameter.In order to further study the flow characteristics of diesel oil carrying water in inclined pipe,a visual two-phase flow loop experiment has been established to study on flow pattern distinction,flow law and critical parameters with the change of velocity and inclination angle in the diameter of 50mm.Based on computational fluid dynamics theory,numerical calculation model of diesel oil carrying water two-phase flow has been built.Compared with the experimental data and verifying grid independence,a reasonable numerical solution and mesh independence solutions are obtained.Fluent software was used to simulate the 3D unsteady flow of diesel oil and water two-phase flow.The influence of velocity,inclination angle and initial water depth on diesel oil carrying water characteristics has been analyzed.The effect and influence of reflux during diesel oil carrying water have been studied.Finally,the results of critical velocity under different inclination angles and diameters are obtained by iteration.Compared with the experimental data,the error is within 10 percent.It is shown that the numerical model established provides significant engineering application value.Through the research above,this paper got the following conclusions.The low-lying stagnant water in the pipeline is caused by the reflux in the water during diesel oil carrying water.When the velocity reaches the critical value,the stagnant water can be carried out of the pipeline by diesel oil.The critical velocity increases with the increase of inclination angle and diameter.It is independent with initial water depth.According to the sensitivity analysis,we find that the problem of low-lying stagnant water can be avoided by increasing the velocity.The sensitive value of critical velocity to inclination angle is 35 degrees.The conclusion above contributes very important engineering value for control of internal corrosion in China product oil pipelines.