Study On Pulse Corona Discharge For The Removal Of Odors

Odor removal has become an important and challenging issue for the world because of the detrimental influence on human beings and potential pollution of the environment. Traditional odor control methods are limitative technically and economically, especially for low concentration and large gas-flow odor abatement. Pulse corona induced plasma discharge process (PCPP) is regarded as a promising technology to control gaseous pollutants. In China, the characteristics of the technology as well as the experimental researches on VOCs treatment have been studied since 1993 in Zhejiang University, results show that PCPP has many advantages: high destruction efficiency, simply installed, high operation efficiency, low energy consumption, widely applicable. Moreover, the technology was applied to odor removal, which produced a good effect.Based on the previous experiments, in this dissertation, the decomposition of odors by pulse corona discharge in the wire-plate reactor(s) was investigated systematically, and the testing malodorants were C₂H₅SH, H₂S and NH₃. A newly developed Blumlein pulse forming network (BPFN) type of narrow pulse generator was used in our experiments. The maximum output power of the generator and the maximum peak voltage were 1 kW and 100 kV, respectively. Total gas-flow rates into the reactor(s) were between 4 and 23 m³ ? h^-1, and all experiments were conducted at the atmospheric pressure. The aims of the experiments were to solve the quantitative design and scale-up problem of the pulse corona process.The main contents as well as the conclusions consist of the following three parts: 1)Decomposition characteristics of single malodorant (C₂H₅SH, H₂S and NH₃) and two groups of mixed malodorants (1. C₂H₅SH + H₂S, 2. C2H5SH + NH₃) in air were investigated utilizing a wire-plate pulse corona reactor. Important parameters, including peak voltage, pulse frequency, BPFN capacitance (inductance), initial concentration, gas-flow rate, initial temperature, which influenced the removal efficiency, were investigated. The results show that the single and mixed malodorants can be treated effectively by pulse corona. When the gas-flow rate was 13 m³ ? h^-1, the removal efficiencies of C₂H₅SH and H₂S for group 1 mixed malodorants at 200 mg ? m^-3 are 95.6% and 100%, respectively, which almost equal to that of the two pollutants separately. The energy cost is about 18.1-22.6 Wh ? m^-3, which is 31.5-45.2% lower than for treating pollutants separately. The removal efficiencies of 105 mg ? m^-3 C₂H₅SH and 40 mg ? m^-3 NH₃ for group 2 mixedmalodorants at the same gas-flow rate are 93.1% and almost 100%, and the energy cost is 18.1 Wh ? m^-3, 55.5% lower than if treated separately. Therefore, it can decrease the energy consumption when the malodorants were mixed.2) Effects of multiple corona reactor modes on pulse characteristics, energy transfer efficiency, and H₂S and NH₃ removal were investigated experimentally by the wire-plate corona reactor(s). Almost 100% removal efficiency was achieved for 200 mg ? m^-3 H₂S with the gas-flow rate of 23 m³ ? h^-1 by the series and parallel modes at 12.8 Wh ? m^-3 and 14.9 Wh ? m^-3, as well as the removal efficiency was only 91% with single mode at 16.1 Wh ? m^-3. In the case of 50 mg ? m^-3 NH₃ removal at the same gas-flow rate, the removal efficiencies with single mode, the series and parallel modes were 64%, 92%, and 70%, respectively. The energy requirement did not increase at the same residence time under the experimental conditions of the single mode with a gas-flow rate of 11.5 m^-3 ? h^-1 and the series or parallel mode with a gas-flow rate of 23 m³ ? h^-1 The experimental results indicate that the series and parallel modes are effective in saving energy consumption, improving removal ability and efficiency, especially for the series mode.3) The by-products were analyzed under different conditions (blank or not, single or mixed, series and parallel). Based on the product and literature analyse, the decomposition mechanis...