Effect of working gases on thermal plasma waste treatment

An electric arc melter used for waste treatment processing is numerically studied. The effects of different plasma working gases are studied by using a laboratory scale test reactor. A two-dimensional finite difference approximation is used to solve the set of governing equations. The Navier-Stokes equations coupled with the combined Maxwell's equation for the electromagnetic fields is used to obtain the temperature and flow fields in the are melter. It is found that the energy efficiency of the air plasma is lower than that of an argon plasma. However, the melted soil volumes are larger using the air plasma than those using the argon plasma. The overall energy efficiency increases cis the gap between the cathode and the soil surface decreases. More uniform gas temperatures are found for the air plasma than that for the argon plasma. Result obtained from the laboratory-scale are melter is used as an input of the energy absorbed into the soil for the USBM arc melter simulation. Results show a maximum temperature of 2195 K at the center of the heat generation and a molten soil exit temperature of 1600 K.