Yoshio Kobayashi

Envirotech Consultant Office
(16-22, Jiyuugaoka, 2-chome, Kumatori-cho, Osaka 590-0423 Japan)

Abstract

So far suppressing the formation of DXNs by reduction of HCl within the municipal refuse incinerator has never been tried. It is thought that there are two reasons for this: (1)There is no technology for effective HCl removal within the incinerator. (2)The causal relation between HCl concentration and the formation of DXNs is unclear. In this paper, it was definitely shown by the examination of the formation mechanism of DXNs through analysis of determined data of chlorinated aromatic compounds formed during the incinerator on the basis of chemical reaction theory that HCl concentration had influence on the formation of DXNs to a great degree, i.e., the HCl gas concentration exponent for the formation of DXNs was not less than 1, and it was described that HCl removal and the suppression of DXNs would be achieved less expensively and effectively by injecting 4-5[micro]m size of sorbents, e.g. NaHCO3 powder into the incinerator through the disperser equipped on the incinerator wall and that this method used in combination with the conventional method would bring further improvement in the suppression of DXNs and that the method would also be available for the control of DXNs retrofit incinerator which is difficult to improve. On the other hand, some experimental data of the independent generation of DXNs by HCl concentration have been reported, so trying to find the cause of this discrepancy is an important subject to investigate in the near future.

Key words: dioxins, chemical reaction theory, HCl removal within incinerator, aerosol reaction, chlorination by HCl