DEVELOPMENT OF COMPACT EXHUST GAS TREATMENT EQUIPMENT FOR DIESEL ENGINE USING DIELECTRIC BARRIER DISCHARGE

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The purpose of this project is to realize a compact system of NOx removal from exhaust gas of diesel engine generator with high efficiency. The project was performed in the following three steps. (1) The first step is to grasp the characteristics of a barrier discharge plasma reactor with a multipoint-to-plane geometry and clarify physical and chemical reactions in the plasma. (2) The second step is to develop a power supply for the plasma reactor. (3) The third is the outlook for practical application of the reactor. In the step(1), we investigated mainly the characteristics of the dielectric barrier discharge between the multipoint and plane electrodes, and an effect of them on the NOx removal. The results are as follows.In regard to the polarity of the streamer, it was clarified that the positive and negative streamers both are generated according to the polarity of applied voltage in the case of the multipoint-to-plane barrier discharge while the positive streamer only is generated … More in the case of the parallel planes barrier discharge. And the current of the micro-discharge is larger between the parallel plane electrodes than the multipoint-to-plane electrodes. In comparison of the gas treatment performance, the NOx removal of the multipoint-to-plane discharge was larger than that of the parallel planes discharge. Concerning the step (2), we did a trial production of a pulse modulator which is composed the IGBT and a pulse transformer. The specification is AC100V in rated primary voltage, 【minus-plus】10kV in secondary output voltage and 2500pps in reputation rate of pulses. With respect to the step (3), an experiment of actual operation was carried out using a diesel engine generator with the rating of 20kVA. An exhaust gas from the generator was flowed into the plasma reactor through a ceramic catalyst and a particle filter. The reactor was made only of a metal, a ceramic and a glass with heat-resistance. A double-walled structure was designed so that it prevents the wall surface from condensing due to wall temperature drop. By this structure, it was confirmed that NOx could be reduced in long time operation of about 12 hours. The filter is maintained by exposing to atmosphere of high temperature and burning out the deposits in about one month. The NOx removal is 35ppm and is corresponding to 10% reduction for the concentration (about 3 50ppm) in the full load. Gas flow rate and input energy are 1.2's mィイD13ィエD1/min. and 9 J/L, respectively. Less