Takeo Urabe* and Harumi Yokokawa**

(* Tokyo Metropolitan Cleansing Laboratory ** The National Chemical Laboratory for Industry)

Abstract

We have previously revealed that Mercury was mostly emissioned in combustion gas as municipal refuse was combusted in a large scale incinerator and mercury species in combustion gas changed remarkably at different places of the incinerator. At first, therefore, experimental studies were undertaken of the effects of gas temperature, HCl concentration and H2O one to mercury species. Next, with reference to data obtained previously by measuring the combustion gas, chemical thermodynamic computation system (CTC/SOLGASMIX) was applied to the combustion gas. The equilibrium calculation of 81 species in various phases was undertaken of the effects of gas temperature, HCl, H2O and O2 concentration and the component (NaCl, Zn) of fly ash. Using the results computed and the experimental results, the changes of mercury species in the combustion gas were thermodynamically considered. The calculation time required was from 10 to 20 seconds each calculation condition and the method of operation was very easy. Therefore CTC/SOLGASMIX was found to be a very useful means of thermodynamic consideration of trace element in combustion gas.

Key words: mercury, combustion gas, municipal refuse incinerator, thermodynamic computation, equilibrium calculation