Fundamental Studies on LID Concentration and Discharge Decomposition of Nitrogen-Dioxide

点击翻译按钮获取中文摘要

The ovjective of this work is to investigate a possibility of concentrating a very small amount of nitrogen-dioxide molecules in a flue gas and decomposing them by discharge and ultra-violet light. Light-induced-Drift(LID) technique is used for the comcentration. In this project the decomposition experiment and LID concentration experiment go side by side. The main results are as follows.1)NO_2 molecules of 80%-90% were decomposed into N_2 and O_2 molecules in a NO_2 glow discharge with pressures between 1 and 7 Torr. It was shown that decomposed species, N_2 and O_<2'> were generated through NO.2)In order to know the effect of ultre-violet light generated in the discharge on the NO_2 decomposition and a possibility of NO_2 decomposition by ultra-violent light, a trial of irradiation of UV light to NO_2 has been carried out. NO_2 was shown to be decomposed into N_2 and O_<2'> however the decomposing porcess was suggested to be different from the discharge process.3) Values of the electron impace ionization coefficient and secondary coefficient for NO_2 gas are a few tens of percentage smaller than those for air, while the electron attachment coefficient for NO_2 is larger than that for O_2.4)Using the results mentioned in 3) and the electron collision cross sections of N_2O which have been reported, the cross sections of NO_2 were estimated by Boltzman equation analysis method. These data play a very important role in analyzing the NO_2 decomposition process in discharges.5)LID experiment system is now constructed, with a dye laser and a laser diode, and an improved type of drift tube. An experiment starts in SF_6 and He buffer gases.The results mentioned above have been obtained, however investigation of NO_2 decomposition by UV light and its mechanism, detailed anallysis of scientific problem of LID concentration, development of NO_2 removal technology in a flue gas are not still finised. Further investifgation have to be carried on.