Simulation Analysis On Flow Field In Pressure Pipeline With High Speed Two-phase Flow And Its Influence Mechanism On Elbow Erosion

The High-speed two-phase flow pressure pipeline is widely used in petroleum,chemical industry and other industries.Under the scour of high-speed two-phase flow,the inner wall of the pipe is easy to produce erosion and thinning damage,which brings huge safety risks to the production of enterprises and even leads to catastrophic accidents.Therefore,it is very necessary to study the erosion reduction damage characteristics,detection and impact mechanism of various factors on erosion damage of high-speed two-phase flow low-temperature pressure pipeline.Based on CNOOC Huizhou petrochemical factory two cryogenic nitrogen gas pipeline of air separation unit as an object,adopts the Ms S magnetostrictive ultrasonic guided wave technique,the use of the magnetostriction effect of ferromagnetic materials and its inverse effect to stimulate and detect ultrasonic guided wave,successful testing in a long distance,except from wall insulating layer of the volume of the pressure pipeline defects;Ultrasonic wall thickness measurement was carried out for the location of the volumetric defect with abnormal signal.In order to study the erosion damage mechanism and characteristics of high-speed two-phase flow pressure pipeline system under certain working conditions,a three-dimensional fluid dynamics mathematical calculation model consisting of straight pipe,curved pipe and gas-liquid two-phase flow was constructed.In this model,with the straight section of the high places of the parallel pipeline system of the remote connection point for the upper and lower parallel straight section of the remote connection points for bottom for boundary conditions of the pipeline system in three degrees of freedom for fixed constraint,using Fluent software,using CFD dynamic mesh grid technology,establish the coupling of the whole system of low pressure pipeline three-dimensional fluid dynamics finite element analysis model.Study of the structure of the differences,the change of working parameters on the characteristics of the flow medium,the influence of the analysis in the direction of flow velocity in the bend structure(radius of curvature,socket connector,miter elbow),working condition(velocity fluctuations and fluid phase change)and weld defects(the weld residual high too,biting,lack of full,wrong while)on high speed flow field,the influence of gas liquid two phase flow calculation elbow medium flow velocity field,temperature field,stress distribution and phase separation characteristics,exactly grasp and analysis the influence factors of pressure pipeline elbow wall erosion corrosion and impact mechanism.Finally,the comparative analysis of different factors under the influence of cryogenic two-phase flow pressure pipeline scour the CFD numerical simulation results,to analyze the rule of pressure pipeline elbow wall erosion damage characteristics,for pressure pipeline inspection regularly provides the basis for determining the focus of the detecting area,and provide theoretical reference for the structure of pressure pipeline design optimization.