Process Optimization And Application Investigation Of Dielectric Barrier Discharge Reactor On Toluene Decomposition

As one of the most important former body of PM2.5, Photochemical smog and O3, the total emission of volatile organic compounds (VOCs) from industrial sources in the country increases every year, resulting in a series of damages to our environment which could not be ignored. Compared with traditional technologies, Dielectric Barrier Discharge (DBD) is considered as one of the most promising technologies for environmental pollution control in recent years, with many advantages such as low cost, high removal efficiency, simple operation, less by-products etc. In the industrial application, the Line-Plane Type DBD reactor highlights the disadvantages of high energy consumption, large occupied area, limited ventilation volume, et al, which constraining its development. To solve these problems, we selected Toluene as the research project and proposed four new types of DBD reactors. Influencing factors such as input power, gas flow rate, inlet toluene concentration, humidity and frequency were taken into consideration. At the same time, we analyzed the gas and solid products, discussed the reaction mechanism of toluene degradation and determined the optimal operating parameters, aiming at providing a basis for industrial applications.(1) The experiment results showed that the toluene removal efficiency (ηtoluene) increased linearly with the increase of input power and the energy consumption also increased. ηtoluene and energy consumption (Ψ) decreased with the increase of inlet concentration. We researched the effect of gas flow rate on ηtoluene and Ψ using the Line-Plane Reactor and Tubular Multilayer Dielectric Barrier Discharge (TM-DBD) Reactor and found that ηtoluene decreased with increasing gas flow rate, while Ψ increased first and then declined. We also found that at the frequency of 21kHz, the Line-Plane Reactor shared high toluene removal efficiency and low energy consumption. As for non-catalytic reactor, humidity showed almost no effect on ηtoluene.(2) For Line-Plane Reactor, when the input power was set at 12000 V, respectively, a ηtoluene of 73.9% and a Ψ of 255 kWh/kg were suggested at a gas flow rate of 2 m/s and an inlet toluene concentration of about 163 mg/m3. Analysis on the gas and solid products of toluene degradation showed that in Line-Plane Reactor, there were lots of macromolecules which were more likely to be the cause of its coking easily.(3) Comparison of three different types of reactors (Combined Plasma Photolysis (CPP), Plane-Plane Reactor, Line-Plane Reactor) showed that there was no significant difference in ηtoluene of the three tubes, while Ψ showed big difference: CPP< Plane-Plane Reactor<< Line-Plane Reactor. Comparing to the Line-Plane Reactor, the Ψ of CPP and Plane-Plane Reactor was much less, at the same time, they showed high ηtoluene, this meant a lot to the industrial applications. With the consideration that the CPP reactor is difficult to clean and maintain, the Plane-Plane Reactor seems to be a good choice for industrial applications. With an input power of 14400 V, an inlet toluene concentration of 170 mg/m3, a gas flow rate of 1.8 m/s, ηtoluene of Line-Plane Reactor, Plane-Plane Reactor and CPP was 77.1%,64.6%, 77.1%, and Ψ was 338 kWh/kg,235 kWh/kg,152 kWh/kg.(4) For Plane-Plane Catalytic Reactor, increasing in humidity inhabited its catalytic effect. Under low humidity conditions, the rηtoluene of Plane-Plane Catalytic Reactor was 20.0% higher than Plane-Plane Reactor and the Ψ was also significantly less than the Plane-Plane Reactor. Analysis on the degradation products showed that catalytic reactor does not produce nitro compounds, and the type and amount of byproducts was relatively small. All these indicated that the Plane-Plane Catalytic Reactor is suitable for industrial applications. With a humidity of 0.4%, an inlet toluene concentration of 208 mg/m3, the Ψ could reach to 88.6% and ηtoluene was 187kWh/kg.(5) With the same inlet toluene concentration, ηtoluene and Ψ of Tubular Multilayer Dielectric Barrier Discharge (TM-DBD) Reactor and Double-Pipe Reactor showed little difference. That is to say, the TM-DBD reactor is applicable for treatment of pollutants with high ventilation rate and could maintain a relatively low energy consumption. What’s more, the GC-MS result showed that the TM-DBD reactor produced less kind of byproducts, causing the fact that it could ease the Line-Plane Reactors’problem of coking easily. With an input power of 10800 V, an inlet toluene concentration of 270 mg/m3, a gas flow rate of 2 m/s, the ηtoluene of Double-Pipe Reactor and CPP was 57.4% and 59.0% and the cp was 193 kWh/kg and 251 kWh/kg.