Optimization Of Cylinder Corona Discharge Reactor’s Structure And Power Supply Types

Corona discharge plasma technologies have a broad application prospect for purifying flue gas. The electrode configuration and its power supply types are directly relevant to the generation of active species and the purification efficiency of flue gas, so design of the reactor’s structure and matching of the power supply for reactor are two key issues in fundamental and application studies of corona discharge plasma technologies. Based on the existing problems of wire-cylinder corona discharge reactor such as small gas flow and low efficiencies on inputting energy, the thesis focused on improvement of its input power and reduction of the energy loss under premise of realizing stable discharge. Through the experimental and theoretical analysis, the influence of the electrode structure and power supply types (positive DC., negative DC and positive pulse discharge) on discharge characteristic was studied and the optimization results were obtained. In addition, examination of the high-energy electron distribution in the corona discharge region by optical emission spectrum technology and removal experiment of NO in simulated flue gas were conducted to verify the feasibility and reliability of optimization results of electrode configuration and its power supply. The main conclusions are as follows:(1) The discharge characteristics of wire electrodes, disc-shaped array electrodes and saw-wheel array electrodes under three power supply types including positive DC, negative DC. positive pulse show that the input power with wire electrodes is far less than the other two electrode configurations, and discharge state of wire electrodes was also unstable; on the contrary, saw-wheel array electrodes has the biggest power input ability and its discharge state was stable. Based on getting the maximum input power density and discharge power, the influence of the power supply types, discharge distance (d), saw-wheel electrode spacing (a). and number of saw wheel (n) on the discharge characteristics of electrodes was studied, and results show that d/a ranged from0.52to0.62, the maximum discharge power and input power density were obtained. Under three power supply types the power output capacity of negative DC is the strongest but the positive pulse is the weakest.(2) The optical emission spectrum was used to detect distribution of N2(C3Hu→B3Hg)in the corona discharge region of reactor and then demonstrate the optimization results from the microscopic mechanism aspects. The results show that saw-wheel array electrodes are more conducive to the production of high-energy electrons with respect to the other two eleetrode configurations; under the same input power, relative intensity of N2(C3Hu→B3Hg) emission spectra followed the order:positive pulse>positive DC> negative DC, which mcaned that positive pulse discharge was more conducive to produce high-energy electrons, while negative DC discharge was disadvantageous for production of high-energy electrons.(3) The results of NO removal with three electrode configurations show that saw-wheel array electrodes were most efficient. NO removal experiments using the optimized reactor show that NO removal rate increased with the increased voltage and flue gas residence time in reactor, but energy utilization decreased; NO removal amount increased with the increase of initial concentration of NO, but removal rate of NO decreased; positive pulse discharge has the largest energy utilization in NO removal. In the simulated Hue gas How rate is0.48m3/h and NO initial concentration is150ppm, the removal rate of positive DC and negative DC arrived100%, while positive pulse discharge arrived80%; the energy utilization relationship of three discharge types were as follows:positive pulse discharge> positive DC> negative DC, the maximum energy utilization of positive pulse discharge was31times as big as that of negative DC.