Research On Erosion Mechanism And Simulation Forecast Technology For Gas-liquid-solid Pipeline Flow In Coal Chemical Processing

With the increasing shortage of international energy, the coal industry is developing rapidly in China. The erosion of equipment and pipe caused by multiphase flow containing solid particles has long been a security risk for enterprises. As the erosion mechanism is very complex and the operating conditions of related equipments and pipes are terrible, it is difficult to forecast the specific failure location. The regular practice in engineering is to upgrade materials and to thicken the wall to prevent erosion perforation, which increase the cost of production greatly with no obvious effect.In this thesis, the typical gas-liquid-solid multiphase flow pipeline that connects the hydrogenation reactor and high temperature and pressure separator of coal-to-liquid is the erosion case. The interaction of corrosion and wear is analyzed firstly. Then, the geometric and mathematical simulation model of the multiphase flow pipeline system is built. Turbulence model, multiphase flow model and the discrete phase model are adopted to solve the multiphase flow field. The distribution of liquid and solid particles in pipes, relative wear rate of pipe wall and the danger zone of entire pipeline system are obtained. Through comparative analysis of different pipe structures and characteristics of solid particles, the different influence factors on the pipeline wear are discussed. The results show that pipeline wear rate decreases with the increasing in diameter in the case of other conditions unchanged. The optimal pipe radius of curvature should be determined according to the actual situation. Spherical solid particles closer to the less wear, and the larger particle size the greater wear rate, until the diameter is large enough, the wear rate increases with the particle size does not change significantly. The piping system is designed and the related analysis and calculation is done. The results show that the wear rate of the new structure is sixty percent of the original. To determine the detection points of the active pipeline system with the erosion prediction method above can significantly reduce the workload of in-service inspection and to ensure the security of the entire pipeline system.The innovation of this thesis is to take the pipeline of coal-to-liquid as a typical gas-liquid-solid multiphase flow to study the interaction of corrosion and wear, to analysis liquid phase fraction and the solid particles wear synthetically and predict erosion failures using Computational Fluid Dynamics Method. The law of the pipeline wear is obtained just changing one single condition. The predicted results and the law of wear, which is applied to the optimization of the pipeline structure and in-service inspection lay a good theoretical basis for the in-depth study of coal liquefaction equipment and pipeline security, stability and long-period operation. This study provides a set of corrosion-wear failure prediction, in-service inspection and structural optimization technology. On the basis of further research, the method is expected to be applied to the abrasion failure analysis, structural optimization, local enhanced processing, in-service detection, life-span prediction, risk assessment and other security engineering of multiphase flow equipment and piping systems in coal chemical industry. The economic and social benefits must be remarkable.