Flow Induced Erosion Failure Prediction And Verification Research Of Coal Liquefaction High Temperature Regulating Valve

The multiphase flow medium transport in the process of coal liquefaction has thecharacteristics such as high concentration of solid phase， high speed and hightemperature．Pipeline system and throttling equipment are always generate wall thicknessreduce and leakage failure accidents，which seriously affect the normal and safe production ofcoal liquefaction engineering．The high temperature regulating valve is located on the front ofvacuum distillation tower is the key equipment in the process of coal liquefaction．In actualproduction，the valve plug and export sleeve often suffered from wear and tear failure，thencausing unplanned shutdown of a complete set of equipment．The existing research work hasnot yet presented effective prediction and checking method，because the failure mechanism iscomplex and relates to many subject area．In this paper，the research object is the high temperature regulating valve which is used incoal liquefaction demonstration project．Combined with numerical simulation and experimentalstudy to reveal the typical material erosion wear mechanism of high temperature regulatingvalve．Then the flow induced erosion prediction method in high temperature influenced bycavitation was established．In addition，proposed to flow velocity，pressure，phase fraction anderosion wear rate as a characterization parameter．The completed research contents andconclusions were as follows：The flow induced erosion mathematical model affected by cavitation was built based on theinherent mechanisms of the containing solid multiphase flow erosion mechanisms． Thecorrectness of computational models were verified by comparing with the cavitation test data inliterature and a actual failure elbow caused by solid multiphase transportation．High temperatureerosion wear experiment apparatus was designed and built．Then experiment study were carriedout about the base material1Cr9Mo and coating material YG8of valve plug and exportsleeve．The influence of impact angle，impact velocity，particle hardness，particle mass，testtemperature were studied．Experiment results obtained velocity exponent and angle function ofthe two materials．Combined with the morphology and surface composition of the testedspecimen by SEM and EDS，the high temperature erosion mechanism of the two materials wasput forward．For the flow induced erosion mathematical model，combined with the velocityexponent and angle function，the distribution of pressure，velocity，vapor fraction and erosion rate on valve plug and export sleeve were obtained according to numerical simulationinvestigation of the flow field in high temperature valve by software FLUENT．Then the erosionrate of high temperature valve was quantitative calculated and the failure area has beenpredicted．The results showed that the top of valve plug，20~50mm away from plug top and450~650mm away from the sleeve export are the high-risk area of flow inducederosion．Finally，the numerical simulation prediction area were validated by the actual failurecases．Based on the combination of flow induced erosion mathematical model building，hightemperature erosion wear experiment and failure case validation．The flow induced erosionprediction method in high temperature influenced by cavitation was established．The innovative research of this thesis is：1) Design and manufacture a new type hightemperature erosion wear experiment apparatus，the erosion angle can be automatically adjustand precise control of temperature(≤500℃)．Apply the experiment apparatus to reveals the wearmechanisms of1Cr9Mo and YG8under the condition of high temperature．2) Using the velocityexponent and angle function which was obtained from experiment to modified the erosion modelwhich is applicable to YG8materials．Combined with numerical simulation，then proposed flowinduced erosion prediction method of the high temperature regulating valve．...