Study On Liquid Accumulation And Liquid Carried By Natural Gas In Hilly-Terrain Wet Natural Gas Pipeline

Wet gas transportation is a common technology in gas produce,water and condensate are always present in the transported natural gas.When the gas flow rate is too low to carry the liquid in the pipeline,liquid accumulation will occur in hilly-terrain wet natural gas pipeline.The liquid accumulation will bring many adverse effects to the gas pipeline.Therefore,it is of great significance to study the law of liquid accumulation and the critical carrying velocity of the wet gas pipeline for the stable operation of the pipeline.Based on the theory of computational fluid dynamics and gas-liquid two-phase flow with low holdup rate,this paper studies and analyzes the characteristics of liquid accumulation in hilly-terrain wet natural gas pipeline by means of numerical simulation.The flow condition,tiling length and velocity field distribution in the pipeline under critical condition were simulated and observed.The results show that with the increase of gas velocity in the pipeline,the liquid accumulation will gradually leave the lower inclined section of the pipeline and spread in the upper inclined section and the local velocity of gas increases.Based on the analysis of the simulation results,it can be seen that the amount of liquid accumulation has no influence on the critical fluid carrying velocity,critical liquid holdup and critical unit pressure drop of the hilly-terrain wet natural gas pipeline;with the increase of pipe inclination,pipe diameter,liquid density and decrease of gas density,the critical fluid carrying velocity and critical unit pressure drop will increase,and the critical liquid holdup will decrease;The impact of the above three factors on the pipeline operating parameters in the critical state is in turn the pipeline inclination,fluid properties,and pipeline inner diameter.By comparing the actual operating parameters of the Sulige gas field with the simulation results,it was found that due to the fact that the gas flow rate could not reach the critical liquid-carrying flow rate during the transportation process,some pipelines in the Sulige gas field generated liquid accumulation and could not be eliminated by gas.