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Jin H.-Z.,Zhejiang Sci-Tech University | Chen X.-P.,Zhejiang Sci-Tech University | Zheng Z.-J.,Zhejiang Sci-Tech University | Ou G.-F.,Zhejiang Sci-Tech University | And 3 more authors.
Meitan Xuebao/Journal of the China Coal Society

To discover the pulverized coal drifting law in the high temperature and high pressure (HTHP) separator of coal liquefaction unit, the physical model was established on the basis of separator's structure and physical characteristics of multiphase flow, the volume of fluid (VOF) model and the discrete phase model (DPM) were used in this numerical simulation to analyze the influence of solid phase mass concentration and particle diameter on the pulverized coal drifting characteristics in HTHP separator. The results show that the mean particle concentration is the largest at gas-liquid interface, and it increases with solid phase mass concentration. There is a negative correlation between pulverized coal drifting ratio in gas outlet and particle size because small particles follow airflow well, and the pulverized coal drifting ratio basically remains unchanged in the same particle diameter when solid phase mass concentration increases to more than 7%. The pulverized coal drifting ratio can be reduced from 2.03% to 0.88% by using a 45° inclined baffle in the upper part of HTHP separator. © 2016, China Coal Society. All right reserved. Source

Ou G.-F.,Zhejiang Sci-Tech University | Yi Y.-W.,Zhejiang Sci-Tech University | Jin H.-Z.,Zhejiang Sci-Tech University | Shu G.-P.,Ordos Coal Oil Company of China Shenhua Oil Coal to Liquid and Chemical Company Ltd | And 3 more authors.
Meitan Xuebao/Journal of the China Coal Society

Angle valve, ball valve and connecting pipe (called as “hypobaric charge-in valve group”) in the front of coal liquefaction hypobaric tower were investigated in this study. RNGk-εturbulent model, evaporation-condensation model, stochastic trajectory model and erosion model, which was corrected by high temperature erosion-wear experiment, were used to calculate the distribution of velocity, phase fraction and erosion rate in the typical opening of angle valve; then the accuracy of numerical calculation was proved by actual damage morphology. The study shows that: the angle valve port, which is a reducing structure, leads to the increase of velocity in valve core, the decrease of pressure, and the transition of liquid-vapor; the velocity of particle was accelerated by the increase of flow velocity on valve core head, the decrease of pressure, the high rate of gasification; the cavitation causes the decrease of effective transmission area of valve group, the increase of flow velocity, then the towing speed of solid increased significantly, so high-speed solid which impacts wall is the main reason for erosion wear. The relationship between the different inlet angles of angle valve and the position of ball valve was compared and analyzed to determine the optimization method of reducing wall erosion rate. © 2015, China Coal Society. All right reserved. Source

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