Rare Earth Tungsten Hot Electron Emission High-temperature Electrostatic Precipitator Cathode Loss Mechanism

The thermal emission style high-temperature electrostatic precipitation is an innovative technique for cleaning up high-temperature flue gases. It has a particular working theory which is different from the corona discharge in traditional ESP. It utilizes the negative electrode made of rare-earth tungsten which emits a large number of electrons when heated to charge dust particles. The charged particulate is collected by grounded plates under the action of the electric field. So it has a good development prospects and the prospects for a wide range of applications in the filed of high temperature dust collection. The key to the technology of the thermal emission style electrostatic precipitation is whether the cathode can emit electron lastingly and high-density or not. So the studying of the loss mechanism is no doubt to be very important, and has especially significance and effect for further development and research in the non-corona high temperature electrostatic precipitation.At our own designed and manufactured experimental platform, show how the emission current density change were observed within 100 hours. The emission current density was steady that was benefit for the high-temperature electrostatic precipitation under high temperature and high voltage. The loss was mainly caused by oxidation reaction accroding to the micro-analysis. The internal organization structure of the material did not change significantly while the material phase and the microstructure of the surface had great change before and after the experiment.In order to study further, isothermal oxidation experiments were accomplished in the static stove under the air without voltage. The dynamic curve and the radox rate constant were obtained through the mass change of the cathode.Based on the experment results, the mathematical model was founded, and the parameters of the model were calculated for the further study.Also the dynamic simulation model was set up in the SIMULINK according the mathematical model. Under the air and the smoke entiroment with temperature of 1073K,1173K.1273K and 1373K, the dynamic simulation was completed without voltage. Then the life of cathode was changed obviously with the rise of temperature and the lower of the concentration of oxygen, and it showed that the temperature and the concentration of oxygen were important parameters during the oxidation. The results of the loss mechanism would have especially significance and effect for further development and research.