High efficiency gas treatment using bi-directional pulse power system

研究了双向脉冲电晕放电高效气体处理系统的特性，测量了双向脉冲放电和单向脉冲放电对NOx的脱除效果。对于每个正的和连续的负电压脉冲，双向脉冲的宽度为100 ns。在任何电压波形下，NO和NOx的脱除率都随着外加电压的增加而增加。在脉冲功率为200 ns，脉冲频率为5 Hz，脉冲功率为100 ns，脉冲频率为10 Hz的情况下，在100 ns的单向电压下，NO和NOx的脱除效率分别为88.6%和84.5%。然而，双向脉冲的这些参数是最低的。双向脉冲的去除率低的原因被认为是双向脉冲的输入能量低于单向脉冲的输入能量。因此，研究了输入能量对去除效率的影响。结果表明，NO和NOx的脱除速率随着输入能量的增加而增加。100 ns的单向脉冲的去除效率优于200 ns的脉冲。对200 ns的双向电压脉冲和200 ns的单向脉冲的去除效率曲线相似，并用高速相机拍摄了放电的分幅照片。据认为，所有脉冲都能同样地去除高达100 ns的NOx。在100 ns后，在双向脉冲和200 ns单向脉冲的情况下，电晕放电仅发生在内电极附近。因此，能源效率并不高。发现最好的方法是在流光到达外电极之前完成电压的施加，并防止电晕放电的产生仅限于内电极附近。

The characteristics of high efficiency gas treatment system by bidirectional pulse corona discharge were investigated.The NOx removal efficiencies were measured using either bidirectional or unidirectional pulse discharges. The width of bidirectional pulse was 100 ns for each positive and successive negative voltage pulse. The NO and the NOx removal rates increase with applied voltage for any voltage waveform. In the case of the pulses of 200 ns for 5 Hz and the pulse of 100 ns for 10 Hz, the NO and the NOx removal rates of 88.6% and 84.5% are obtained for the unidirectional voltage of 100ns. However, these for the bidirectional pulse are the lowest. The reason, why the removal rate for the bi-directional pulse is low, is considered that the input energy for the bidirectional pulse is lower than that for the unidirectional pulse. Therefore, the removal rates as functions of input energy are investigated. As a result, the NO and the NOx removal rates increase with increasing input energy. The removal efficiency for unidirectional pulse of 100 ns is superior to that for the pulse of 200 ns. The removal efficiencies for the bidirectional voltage pulse of 200 ns and that for the unidirectional pulse of 200 ns are on the similar curve.Also, framing photographs of discharge were taken by using high-speed camera. It is thought that all pulses equally remove NOx up to 100 ns. After 100 ns, the corona discharge is occurring only near the inner electrode in the case of the bidirectional pulse and the unidirectional pulse of 200 ns. Therefore, the energy efficiency is not high. It is found that the best way is to finish the application of voltage before streamers reach the outer electrode and to prevent the generation of corona discharge limited to the vicinity of the inner electrode.