Study On Pulse Corona Discharge Combined With Activated Carbon Fiber 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 high volume low concentration emissions. 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 Univ., results show that PPCP can be well used in such area. There are two critical issues in the practical implementation of PPCP of pollutants: electrical energy consumption, and byproduct identification.Based on the previous experiments, in this dessertation, the decomposition of odors by pulse corona discharge in the wire-plate reactor with the combination of activated carbon fibers was investigated, and the testing malodorants were C₂H₅SH, H₂S and NH₃. A newly developed Blumlein pulse forming network (BPFN) type of narrow pulse genereator was used in our experiments. The maximum output power of the generator and the maximum peak voltage were 1kW and 100 kV, respectively. Total gas-flow rates into the reactor were between 4 and 23 m³/h, and all experiments were conducted at the atmosphere pressure and temperature. The main contents of the researches are four aspects: 1) the investigation of pulse plasma reactor discharge characteristics;2) the comparison of the DBDR and the PCR;3) the decomposition characteristics of C₂H₅SH and H₂S by a wire-plate pulse corona reactor;4) the investigation of the combination of non-thermal plasma and activated carbon fibers (ACF) for decomposition of H₂S and NH₃;5) the analysis of the byproducts. It is expected that the experiments can be used as reference for solving the quantitative design and scale-up problem of the PPCP. The conclusion shows:1) The influences of factors such as power supply capacitance, plate distance and dielectric barrier on discharge characteristics were investigated. The results show that increasing the power supply capacitance can improve the utilization efficiency ofdischarge energy;increasing the plate distance will result in higher peak voltage, lower peak current and shorter width time and achieve better waveforms;the dielectric barrier can help solving the spark discharge, and also improve the utilization efficiency of discharge energy. It is recommended that the 20 nF power supply capacitance and 120 mm plate distance should be choosed.2) Two kinds of reactors, DBDR and PCR, are investigated. The results show that the DBDR has the higher P value and lower Q value, then larger SIE, which is more suitable for exhaust gas treatment;the removal efficiency of C2H5SH were 95.33% and 88.87%, respectively, when the input voltage were lOkV;while the ozone yield from the DBDR is lower than the one from the PCR no matter whether the C2H5SH is contained.3) Different parameters that influenced on removal efficiency were investigated, such as inject power, resident time, mixed malodorants. The results showed that the removal efficiency of 200mg/m3 H2S and C2H5SH can be 100% and 96.6%;shorter resident time, lower removal efficiency. It is considered that 10-13s was suitable for effective H2S decomposition. The removal efficiencies of mixed C2H5SH, H2S decreased compared with the respective decomposition under the same input power, while the energy consumption decreased form 33.0W ? h/m to 18.1 22.6 W ? h/m3.The O3 generation was also concerned. SO2, CO2 and CO were found during the decomposition period, S was also found in the reactor.4) The influences of input voltage, initial concentration and resident time for decomposition of H2S and NH3 with the combination of pulse discharge plasma and ACF were investigated. The results showed that the removal efficiencies of H2S, NH3 were improved from 88% and 40% to 100%, the O3 yield was decreased from HOppm, 108ppm to almost zero. The increasing initial concentration and shorting resident time can both result in more quickly broken through of the ACF. The influence was more obviously to the H2S decomposition.5) The byproducts were analysed under different conditions (blank or not, with plasma or ACF). Based on the product and literature analyse, the decomposition mechanisms of H2S and NH3 were discussed.