Liquid-carrying Theory And Drainage Technology Of Undulating Wet-gas Pipelines

With the widespread application of wet-gas transport technology,the problem of pipeline liquid-loading has become the most prominent issue affecting the safe,stable and efficient of production.Now,most gas pipelines urgently need to determine the pipe liquid-loading/ liquid-carrying status and implement economical and effective drainage technology.In this paper,we break through the traditional idea of two-phase flow studying in hilly-terrain pipes,and studying from the perspective of liquid carrying theory.The paper establish a critical liquid carrying model that is suitable for hilly-terrain pipes on the ground and analyze the applicability of the foam draining technology and vortex drainage technology in the hilly-terrain pipes.Specific tasks include:This paper builds a visually hilly-terrain pipelines multiphase flow experimental loop,and studies the liquid-carrying dynamic characteristics and the characteristics of the liquid phase motion under the critical liquid-carrying state with the help of high-speed camera;using visual inspection,differential pressure fluctuation,ultrasonic Doppler velocity measurement(UDV)to recogenite the critical liquid-carrying state and measure the critical liquid-carrying flow rateThe study determined that the elbow and upturned section is the crumbling of pipeline liquid-loading problem,and the stability of the liquid-caryying status in upper pipe is the sufficient conditions for the liquid-caryying status in elbow;the liquid droplets can not exist stably under the condition of critical liquid-carrying,and the liquid film shows non-uniform distribution.The inlet conditions and the dip angle of the liquid pipe will affect the liquid phase distribution and the critical liquid-carrying rate.Based on the experimental data,optimize and improve the existing model,and build the critical liquid-carrying combined model in inclined pipe considering the characteristics of gas and liquid movement.The combined model error analysis results are good.Coupling the combined model with the hydraulic calculation model of the hilly-terrain pipeline,obtain the critical liquid-carrying model of the hilly-terrain pipeline is obtained.The reliability of the model is verified by gas field production data.Based on the liquid-carrying theory,this paper test the applicability of the foam drainage and vortex drainage technology.The two drainage technologies in the hilly-terrain pipeline show draining effect and drag reduction effect.The former is suitable for pipeline with big angle or low liquid flow rate and the effect will be better with increased concentration,secondary mixing measures and other measures;the latter is more suitable for pipeline with small angle or heigh gas velocity,so it is necessary to judge the feasibility of vortex tools before its implementation.The critical liquid-carrying combined model of hilly-terrain pipelines established by this pape provides a theoretical basis for the prediction of liquid-carrying / liquid-carrying status in ground pipelines and the research on the liquid-draining technology.The conclusion of the test on foam drainage technology and vortex drainage technology is also a great significance for fieldwork of these technologies.