Numerical Study On The Characteristics Of Bottom Elbow Effusion In Wet Natural Gas Pipeline

In the process of natural gas transportation,due to the terrain along the undulating terrain and temperature changes,pressure changes,it will be in the bottom of the gas pipeline to form a liquid.The presence of effluent affects the safety and efficient operation of the entire gathering and transportation pipeline.And the increasing gas demand challenging moisture pipeline safety and efficient transportation.The most important way to remove the eluent from the elbow is to increase the inlet speed of the gas.In order to ensure the safe and efficient operation of the gas pipeline,Therefore,it is significant to study the critical state and critical flow velocity of the fluid at the bottom of the gas pipeline,which is driven away from the top of the pipeline.This article is based on the basic principles of fluid mechanics and the basic control equations of fluid motion,Combining the theoretical knowledge of low liquid content gas liquid two phase flow,The CFD software FLUENT was used to simulate the inlet critical velocity of the bottom elbow effluent from the wet natural gas pipeline.In this paper,the critical pressure drop,critical state when the critical line pressure drop,the critical liquid holdup and the critical length of the liquid film in the critical section are studied in the critical state;The velocity field distribution when the effluent is driven away and the gas-liquid interface morphology in the critical state;At the same time,the effects of four factors,such as the amount of fluid in the pipeline,the inclination of the pipeline,the diameter of the pipe and the viscosity of the fluid,on the critical velocity are studied.The simulation results show that in the critical state,the liquid layer is almost flattened on the uplift section,but the tiling thickness is not completely uniform and thick,but relatively thin at both ends of the liquid layer along the pipeline direction.At the critical flow rate,there is no obvious sign of reflux in the upper segment;In the critical state,the interface morphology of gas-liquid is in good agreement with the FLAT model proposed by Taitel & Duekler;In the critical state,the liquid holdup is kept constant,which proves the theory that the fluid is uniform and thick in the upper section;The critical pressure drop is not directly related to the size of the effluent,but with the increase of the inclination of the pipeline;The critical flow rate increases with the the pipe inclination angle,and increases with the diameter of the pipeline,and increases with the fluid volume.The results of this study have some guiding significance to prevent the formation of effluent in the fluctuating pipeline,At the same time,It is helpful to clarify the mechanism of the displacement of the bottom of the wet natural gas pipeline,which provides the necessary theoretical basis for the design and construction of the wet natural gas pipeline.At the same time,it is helpful to clarify the mechanism of the displacement of the bottom of wet gas pipeline bottom elbow effusion,which provides the necessary theoretical basis for the design and construction of the wet natural gas pipeline.