Research On The Method Of Thermal Plasma Field Control And Parameter Monitoring

Based on the current harm caused by pollutants such as solid waste and exhaust gas to the environment and human health,while traditional pollutant treatment methods are faced with problems such as secondary pollution and poor versatility,plasma technology is an emerging technology for harmless treatment of pollutants.Plasma can be divided into cold plasma and thermal plasma by whether it is thermally balanced.There have been many successful applications of cold plasma,but the use of thermal plasma to deal with dangerous pollutants is still relatively few.Compared with the former,Therefore,it is an ideal harmless treatment technology that can decompose some pollutants which are difficult to decompose and has no specific treatment object.However,the energy gradient distribution of the current thermal plasma is too large to directly contact the gas and pollutants when used directly,and the expansion of arc area is faced with the problem of high power supply.In order to solve the problem that the current thermal plasma technology is difficult to be practical,this paper designs a new plasma sliding arc generator,based on the typical sliding arc structure,At the same time,a low power supply system is established to drive the device,and the structure is improved on the basis of the flow field and plasma field of the device are analyzed by means of simulation.Finally,the influence of external parameters on the thermal plasma field is tested through experiments.The main research contents of this paper can be summarized as:(1)Design of thermal plasma field generator: the electrode structure is based on the principle of sliding arc.In addition to the working electrode that generates thermal plasma,a set of auxiliary high-voltage electrodes are also designed,and it is used to break the air in advance so that the working electrode can arc in low voltage,which is distributed in a cross shape with the working electrode,A large current circuit is designed to drive the working electrode.The inverter topology of the full-bridge circuit and the feedback control method combining the current loop and the voltage loop are used to ensure the stable output of the power supply.(2)Finite element simulation analysis: the theoretical analysis is divided into flow field simulation of gas channel and plasma field simulation of electrode.Flow field simulation involves the coupling of airflow and the selection of model.Plasma discharge theory involves electron drift diffusion,particle collision,heavy matter transport,chemical reaction,etc.ANSYS CFX was used to establish the simulation model of the flow channel,then improve the gas path structure of the device according to the simulation to establish a stable flow field condition for the plasma field generation;the plasma field simulation uses COMSOL Multiphysics to establish the reaction model of the plasma generation space,it is found that the field strength is the largest at the minimum electrode gap,and the range of the surrounding air conductivity under the interaction of the two groups of electrodes is clarified.(3)Experimental construction of thermal plasma generator: equipped with a power supply system and gas channel,under atmospheric pressure environment,by adjusting the air valve and current to explore the influence of different power and flow velocity on the stretching length of arc and arc cycle under the atmospheric pressure environment,but after the current reaches 7A,the enhancement is very small.Therefore,properly increasing the flow rate of the gas flow will extend the elongation of the thermal plasma arc,but when the flow rate is increased too much,it is not suitable to the maintenance of the thermal plasma arc.(4)Monitoring system based on Internet of Things technology: A monitoring system of Internet of things based on ARM9 was built,which includes two parts: on-site monitoring and remote monitoring.To ensure that the device parameters can be checked in both the operating interface of the device and the remote upper computer,so as to improve the monitoring efficiency of the working status and processing results of the device.