Ozone Zero Phenomenon in Ozone Generator Equiped with Coaxial Cylinder Electrodes Covered by Dielectrics

Abstract

Ozone generators of dielectric barrier discharge (DBD) are mainly used for water and waste water treatment. Recently, they are also used for cleaning of food product machines, semiconductors processes, pulp bleaching field and so on. It is well-known that ozone concentration composed by DBD type ozone generator decreases with time when high purity oxygen used for feed gas. This is named by us, ozone zero phenomenon (OZP). The causes of the phenomena have been investigated experimentally in the world wide industries us. One of the causes is considered as an electrode material by discharge in the generator metal oxides formed from stainless steel electrode. We have studied the ozone generation characteristics using high purity oxygen as a feed gas and ozone generator of which both electrodes covered with dielectrics. It was found that using only high purity oxygen as a feed gas, ozone concentration decreased from 200g/m3(N) to 54g/m3(N) during about 5 hours. However, adding 0.1vol% of nitrogen into oxygen, ozone concentration increased rapidly over the initial maximum ozone concentration of 216g/m3(N). After that, the concentration of ozone gradually decreased with time. Therefore, adding nitrogen into oxygen has the effect of recovery of ozone concentration in the same generator. The maximum ozone concentration was obtained when 0.1-0.6vol% of nitrogen gas was added to oxygen gas. OZP is caused by ozone generator even when both electrodes are covered with dielectrics. The metal oxide is produced on electrode is not the cause of OZP. Ozone concentration can be increased by adding nitrogen into oxygen.