Design And Test Of Medium Power DC Arc Plasma Generator And Research On Magnetron Technology

With the continuous development of the world economy,China has now become the second largest economy in the world.Economic growth has been accompanied by a dramatic increase in waste production.The rapid and efficient treatment of medical waste has become an urgent problem under the background of the new epidemic sweeping the world.In order to better respond to the policy needs,a new type of plasma technology has gradually entered the public’s vision.Due to its high energy density,high temperature and no pollution,plasma waste treatment has more and more advantages in medical waste treatment.Plasma arc generator(torch)is the main equipment of the processing system.However,in the research of arc plasma generator by domestic and foreign scholars or institutions,most of the research subjects are high power or minimum power conditions.There are still few researches on DC arc plasma generator at medium power in China and its working characteristics are still unclear.There is no systematic design scheme to realize technology transformation.In addition,due to the high energy density of plasma arc generator,serious electrode ablation and other problems still require further exploration and solutions.Based on the self-built design theory,the internal working process of the generator is deeply studied and analyzed,and the advantages and disadvantages of different design methods are compared.Based on a large number of engineering empirical data in the literature,the preliminary design of some structures is carried out.Based on the principle of avoiding shunt phenomenon,the design criterion of intermediate connection structure is deduced and put forward.The whole structure adopts more flexible multi-stage structure,which has a strong advantage over the traditional two-pole structure.The cooling method adopts integrated water cooling method to reduce the electrode wall surface and reduce the complexity of the structure.In order to explore the characteristics of jet flow and heat transfer in arc plasma torch and provide theoretical guidance for ground ignition test,a calculation method based on the secondary development of Fluent was proposed.The reasonable assumptions were used to simplify the calculation process and reduce the consumption of resources.The calculation method of compensated pressure drop is adopted and the correctness of the calculation method is verified by comparing with literatures.The rationality of the design is verified by the numerical simulation of the designed generator.In this paper,an ignition test experimental system is built to explore the actual performance of the designed arc generator.Ignition was successfully realized under the condition of no-load voltage 350 V,constant output current 110 A and gas flow rate of 9-10L/min,and stable jet was ejected from anode.The volt-ampere characteristic curve shows a negative resistance characteristic.When the current increases,the arc voltage shows a downward trend under the premise of constant inlet flow.The jet length shows an inverted U shape with the change of gas flow rate.Based on the experimental data,the internal process of the arc generator is numerically analyzed by using the principle of similarity,and the experimental correlation formula for calculating volt-ampere characteristics is proposed,which has a good accuracy in the design power range of 13.2 kW to 21.168 kW.The influence of magnetic control technology on electrode life was studied by numerical calculation and experiment.The experiment shows that the ablation rate of anode decreases by about 14% under the action of external magnetic field.