SCI和EI收录∣中国化工学会会刊

Chinese Journal of Chemical Engineering ›› 2021, Vol. 35 ›› Issue (7): 152-162.DOI: 10.1016/j.cjche.2021.03.009

• Fluid Dynamics and Transport Phenomena • Previous Articles     Next Articles

Multi-fluid Eulerian simulation of binary particles mixing and gas-solids contacting in high solids-flux downer reactor equipped with a lateral particle feeding nozzle

Qiang Zheng1, Jingxuan Yang1, Wenhao Lian2, Baoping Zhang1, Xueer Pan1, Zhonglin Zhang1, Xiaogang Hao1, Guoqing Guan3   

  1. 1. School of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China;
    2. School of Chemical Engineering and Technology, North University of China, Taiyuan 030051, China;
    3. Laboratory of Energy Conversion Engineering, Institute of Regional Innovation (IRI), Hirosaki University, 2-1-3 Matsubara, Aomori 030-0813, Japan
  • Received:2020-11-03 Revised:2021-03-08 Online:2021-09-30 Published:2021-07-28
  • Contact: Jingxuan Yang, Xiaogang Hao, Guoqing Guan
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (U1710101). The authors also thank Mr. Junwu Wang for his help in establishment of the multi-fluid Eulerian model.

Multi-fluid Eulerian simulation of binary particles mixing and gas-solids contacting in high solids-flux downer reactor equipped with a lateral particle feeding nozzle

Qiang Zheng1, Jingxuan Yang1, Wenhao Lian2, Baoping Zhang1, Xueer Pan1, Zhonglin Zhang1, Xiaogang Hao1, Guoqing Guan3   

  1. 1. School of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China;
    2. School of Chemical Engineering and Technology, North University of China, Taiyuan 030051, China;
    3. Laboratory of Energy Conversion Engineering, Institute of Regional Innovation (IRI), Hirosaki University, 2-1-3 Matsubara, Aomori 030-0813, Japan
  • 通讯作者: Jingxuan Yang, Xiaogang Hao, Guoqing Guan
  • 基金资助:
    This work was supported by the National Natural Science Foundation of China (U1710101). The authors also thank Mr. Junwu Wang for his help in establishment of the multi-fluid Eulerian model.

Abstract: The performance of binary particles mixing and gas-solids contacting, which is considered qualitatively to have a significant influence on the heat transfer in internal heated circulating fluidized beds, is carefully investigated by means of a numerical approach in the newly developed high solids-flux downer lignite pyrolyzer (φ0.1 m×6.5 m). Since binary particles are used in this system, a reasonably validated 3D, transient, multi-fluid model, in which three heat transfer modes relating to the convection, conduction and radiation are considered, is adopted to simulate the flow behavior, temperature profiles as well as volatile contents. The simulation results showed that the solids stream impinges the left wall surface initially and turns towards the right wall in the further downward direction and then shrinks during this process resulting in that the solids concentrate a little more at the central region. In the further downward section of the downer, the particle flow disperses near the right wall and develops uniformly. Meanwhile, the coal phase is slowly heated in the downer and it is found that most of the heat absorbed by the coal is from the convection heat transfer mode. To explore the heat transfer mechanism more quantitatively, two indexes (mixing index and contacting index) are proposed, and it is found that the mixing index initially increased fast and later remained at a relatively flat state. For the contact index, it shows a trend with a first rising and then falling, finally rising continuously. Also, it is found that the convection heat transfer is closely correlated to the contacting status of gas-coal which indicates that the improving of the gas-coal contacting efficiency should be an effective way to strengthen the coal particle heating process.

Key words: CFD, Multiphase flow, Downer reactor, Numerical simulation, Heat transfer

摘要: The performance of binary particles mixing and gas-solids contacting, which is considered qualitatively to have a significant influence on the heat transfer in internal heated circulating fluidized beds, is carefully investigated by means of a numerical approach in the newly developed high solids-flux downer lignite pyrolyzer (φ0.1 m×6.5 m). Since binary particles are used in this system, a reasonably validated 3D, transient, multi-fluid model, in which three heat transfer modes relating to the convection, conduction and radiation are considered, is adopted to simulate the flow behavior, temperature profiles as well as volatile contents. The simulation results showed that the solids stream impinges the left wall surface initially and turns towards the right wall in the further downward direction and then shrinks during this process resulting in that the solids concentrate a little more at the central region. In the further downward section of the downer, the particle flow disperses near the right wall and develops uniformly. Meanwhile, the coal phase is slowly heated in the downer and it is found that most of the heat absorbed by the coal is from the convection heat transfer mode. To explore the heat transfer mechanism more quantitatively, two indexes (mixing index and contacting index) are proposed, and it is found that the mixing index initially increased fast and later remained at a relatively flat state. For the contact index, it shows a trend with a first rising and then falling, finally rising continuously. Also, it is found that the convection heat transfer is closely correlated to the contacting status of gas-coal which indicates that the improving of the gas-coal contacting efficiency should be an effective way to strengthen the coal particle heating process.

关键词: CFD, Multiphase flow, Downer reactor, Numerical simulation, Heat transfer