Study On Degradation Of PCDD/Fs In MSWI Fly Ash Using Gliding Arc Plasma In Tornado Reactor

Gliding arc discharge plasma is the cyclical swing non-equilibrium plasma at atmospheric pressure, which has a dual character of thermal and non-thermal plasma. As promoting the electron energy, high-energy electrons and strong oxidizing free radicals, the non-equilibrium plasma technology is attracted wide attention in pollutant emission control and material processing. In this study, the latest version of gliding are reactor, so-called gliding arc in tornado reactor, is employed innovatively to decomposition of hexachlorobenzen in model fly ash and PCDD/Fs in MSW fly ash. The primary PCDD/Fs destruction mechanism is proposed. The main research contents are as followed:1. Studies on physical properties of gliding arc in tornado(GAT) plasma. In order to analyze electrical characteristics of gliding arc at different working conditions, arc voltages and currents are measured by using high-speed video camera and oscillograph. The gas input configuration of GAT reactor is quite different from the traditional gliding arc reactor. Therefore, the effect of gas input configuration on GAT physical properties is studied. Two working modes and the stable working mode of GAT are concluded based on the foregoing experimental results.2. Studies on the destruction of HCB in simulated fly ash using gliding arc in tornado. The emission concentration of PCDD/Fs between all types of chlorobenzene or HCB (Hexachlorobenzene, C6C16) has a high degree of consistency. Hence, we choose HCB as an example, studies on the degradation process of that in simulated fly ash under different experimental conditions. According to the gliding arc discharge plasma physical characteristics and experimental results, the destruction process of HCB in simulated fly ash was studied.3. Studies on the destruction of PCDD/Fs in fly ash using gliding arc in tornado. Solid waste fly ash is treated by GAT and its high concentration PCDD/Fs are destructed. The experimental results indicate that the mass destruction rate and I-TEQ destruction rate of PCDD/Fs can be achieved up to66.2%and71.3%, respectively, with oxygen as working gas. The I-TEQ concentration of PCDD/Fs in the off-gas is326.75pg-TEQ/NmJ. Based on analysis of PCDD/Fs congeners distributions in original fly ash, treated fly ash and off-gas, two major PCDD/Fs destruction routes are proposed:(1) PCDD/Fs are destructed by the direct interaction between GAT and fly ash surface;(2) PCDD/Fs are evaporated to gas phase and then destructed in the GAT by gas phase reactions.