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Plasma Sci. Technol. ›› 2018, Vol. 20 ›› Issue (6): 065502.doi: 10.1088/2058-6272/aaa969

• Plasma Technology • Previous Articles     Next Articles

Understanding CO2 decomposition by thermal plasma with supersonic expansion quench

Tao YANG (杨涛), Jun SHEN (沈俊), Tangchun RAN (冉唐春), Jiao LI (李娇), Pan CHEN (陈攀) and Yongxiang YIN (印永祥)   

  

  1. College of Chemical Engineering, Sichuan University, Chengdu 610065, People’s Republic of China
  • Received:2017-11-29 Published:2018-01-16
  • Supported by:

    The authors gratefully acknowledge the funding of National Natural Science Foundation of China (Grant No. 11775155).

Abstract:

 CO2 pyrolysis by thermal plasma was investigated, and a high conversion rate of 33% and energy efficiency of 17% were obtained. The high performance benefited from a novel quenching method, which synergizes the converging nozzle and cooling tube. To understand the synergy effect, a computational fluid dynamics simulation was carried out. A quick quenching rate of 107 Ks−1 could be expected when the pyrolysis gas temperature decreased from more than 3000 to 1000 K. According to the simulation results, the quenching mechanism was discussed as follows: first, the compressible fluid was adiabatically expanded in the converging nozzle and accelerated to sonic speed, and parts of the heat energy converted to convective kinetic energy; second, the sonic fluid jet into the cooling tube formed a strong eddy, which greatly enhanced the heat transfer between the inverse-flowing fluid and cooling tube. These two mechanisms ensure a quick quenching to prevent the reverse reaction of CO2 pyrolysis gas when it flows out from the thermal plasma reactor.

Key words: CO2 conversion, thermal plasma, CFD, quench, gas dynamics