摘要
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 10~7Ks(-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.
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 10~7Ks(-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.
作者
杨涛
沈俊
冉唐春
李娇
陈攀
印永祥
Tao YANG;Jun SHEN;Tangchun RAN;Jiao LI;Pan CHEN;Yongxiang YIN(College of Chemical Engineering,Sichuan University,Chengdu 610065,People's Republic of China)
基金
the funding of National Natural Science Foundation of China (Grant No.11775155)