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Inlet effect on the coal pyrolysis to acetylene in a hydrogen plasma downer reactor

Authors

  • Y. Cheng,

    Corresponding author
    1. Department of Chemical Engineering, Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Tsinghua University, Beijing 100084, PR China
    • Department of Chemical Engineering, Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Tsinghua University, Beijing 100084, PR China
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  • J. Q. Chen,

    1. Department of Chemical Engineering, Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Tsinghua University, Beijing 100084, PR China
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  • Y. L. Ding,

    1. Department of Chemical Engineering, Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Tsinghua University, Beijing 100084, PR China
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  • X. Y. Xiong,

    1. Xinjiang Tianye Corporation, Shihezi 832000, PR China
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  • Y. Jin

    1. Department of Chemical Engineering, Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Tsinghua University, Beijing 100084, PR China
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Abstract

Coal pyrolysis to acetylene in hydrogen plasma is a clean process for the coal utilization. A gas–solid downer reactor was employed to facilitate the high temperature reactions of coal pyrolysis in milliseconds. The effect of the inlet design on the coal injection was studied using CFD simulations, which were qualitatively compared with the cold model experiments in the prototype of a 2 MW hydrogen plasma reactor. The results revealed that the distribution of the coal particles near the inlet nozzles was significantly influenced by the layout of the flat-shaped nozzles and the operating conditions. Accordingly the heating efficiency of the particles by the hot gas showed strong dependence on the inlet design. The hot model tests demonstrated that the reactor performance characterized by the concentration of acetylene in the product gas increased from ∼7.6 to 9.6% by optimizing the nozzle design, which indicated the critical role of the nozzle design in the coal pyrolysis process.

Abstract

La pyrolyse du charbon en acétylène dans un plasma d'hydrogène est un procédé propre pour l'utilisation du charbon. On a employé un réacteur à écoulement descendant pour faciliter les réactions à haute température de la pyrolyse du charbon en millisecondes. L'effet de la conception de l'orifice d'admission sur l'injection de charbon a été étudié à l'aide de simulations CFD, qui ont été qualitativement comparées aux expériences dans un modèle froid d'un prototype de réacteur à plasma d'hydrogène de 2 MW. Les résultats révèlent que la distribution des particules de charbon près des orifices d'admission est significativement influencée par la disposition des orifices de forme plate et les conditions opératoires. En conséquence, l'efficacité de chauffe des particules par le gaz chaud montre une forte dépendance envers la conception de l'orifice d'admission. Les tests de modèle chaud montrent que la performance du réacteur caractérisée par la concentration d'acétylène dans le gaz de produit augmente de ∼7.6 à 9.6% en optimisant la conception de l'orifice, démontrant ainsi le rŏle critique de la conception de l'orifice dans le procédé de pyrolyse du charbon.

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