Temperature Diagnosis Of Magnetically Rotating Arc Plasma And Its Application In Methane Reforming

Thermal plasma has the advantages of high electrothermal conversion efficiency,high reaction temperature,high energy density and adjustable atmosphere.It is an advanced method of chemical strengthening,and widely applied in preparation of acetylene and syngas,solid waste treatment and so on.The temperature distribution in the thermal plasma reactor is a key factor affecting the efficiency of the reaction.However,the thermal plasma temperature can be 2000 to 20000 K,while the reactor often requires a good air tightness,which make the temperature distribution in the reactor difficult to be obtained by conventional detection means.In this paper,the emission optical spectroscopy diagnosis technique is used for the first time to study the temperature distribution under the condition of pure gas feed and the reactive feed in the magnetic rotating arc plasma torch.Combined with the results of computer simulation,the influence of operating conditions on temperature distribution and product composition was clarified,and the unique advantages and development potential of magnetically rotating arc plasma torch were revealed.The effect of different operating conditions on the plasma temperature was investigated by using the emission optical spectroscopy technique to diagnose the magnetically rotating arc plasma under pure argon feed.Studies have shown that the plasma temperature and electron temperature is approximately equal,which can reach more than 10000 K.The experimental results showed that,under the condition of pure argon feed,the increase of the input power and the decrease of the feedrate can improve the plasma temperature.The increase of the magnetic induction intensity is beneficial to the formation of uniform thermal plasma.Fluent was used to simulate this process,and the results were in good agreement with the experiment.During the carbon dioxide reforming of methane to syngas by magnetically rotating arc plasma,the temperature distribution information in the plasma torch was studied by emission optical spectroscopy.With the increase of CH₄ concentration in the raw materials,the conversion of CH₄ and the selectivity of H₂ continued to decrease,and the selectivity of CO increased continuously,while the conversion of CO₂ increased and then decreased,and the plasma temperature decreased.With the increase of input power,the conversion of CO₂ and CH₄ and the selectivity of CO increased,while H₂ selectivity increased first and then decreased,and the plasma temperature increased.As the magnetic induction intensity increased,the feed conversion and product selectivity increased,the thermal plasma temperature distribution was more uniform.The conversion,yield and temperature during the reforming progress were numerically simulated by Chemkin-PRO software.Under different CH₄/CO₂ ratio,the simulation results of CH₄ and H₂ were in good agreement with experimental results,and the simulation of CO₂ and CO had some similarity with experimental results in the trend.With the increase of input power,system pressure and anode diameter,CH₄ conversion,CO₂ conversion,H₂ yield and CO yield all increased.However,the high input power had a limited effect on the reaction.The temperature difference between the temperature from emission spectroscopy and the simulated temperature was about 1000K,but the change trend was very consistent.