Takashi Nishitani*, Isao Fukunaga*, Hisao Itoh* and Tomohiro Nomura**

* Osaka City Institute of Public Health and Environmental Sciences
** Department of Mechanical Engineering, Faculty of Engineering, Osaka City University

+ Correspondence should be addressed to Takashi Nishitani:
(8-34 Tohjocho Tennohji-ku Osaka 543 Japan)

Abstract

It is said that 70-90% of the mercury in municipal refuse incinerator flue gas is mercury chloride (HgCl2) and the rest is metal mercury (Hg0). HgCl2 is generally easy to remove compared with Hg0. It is possible to remove HgCl2 with high efficiency using fabric filters, with the gas temperature at less than 150*C[Celsius degeree]. The purpose of this work, therefore, is to develop a dry mercury treatment system which achieves a high mercury removal efficiency of up to 80% for metal mercury at 200*C[Celsius degeree]. The laboratory experiments were performed on fly ashes collected from electrostatic precipitators in municipal refuse incineration plants.

The following points have become clear from the experiments. Metal mercury can be removed with high efficiency at 200*C[Celsius degeree] using fly ash from the municipal refuse incinerator. Both adsorbent substances such as unburnt carbon and CaCl2 contained in fly ash participates in the metal mercury removal mechanism. Adsobent substances and CaCl2 had a low removal efficiency when taken separately, but when they were present together, they had a high removal ability.

Key words: municipal refuse incinerator, flue gas treatment, mercury, fly ash, fabric filter