Basic Study on Exhaust Gas Treatment from Waste Pyrolysis by Metal Oxides Absorption

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Hydrogen chloride and hydrogen sulfur discharged from waste pyrolysis process causes environmental disasters and severe corrosion and erosion of the gasifier. In general, natural resources of some metal oxides are utilized for the removal of of these acid gases from exhaust gas. Considering the saving of natural resources for the future, it is very important to develop the new gas treatment system that needs the minimum natural resources for achieving the regulation. We focused on the solid waste such as coal burnt ash and coal slag involved in metal oxides which has reactivity towards acid gases. Based on the point, we evaluated the ability of these solid wastes as acid gases sorbent.HCI absorption experiment by coal burnt ash showed that the HCI absorption capacity increased with the increment of the amount of Ca-compounds contained in the ash. There was an optimum temperature range between 673 and 873K for HCI absorption for the employed ash samples. It was found that a part of Ca component did not show any reactivity for HCI absorption. Such Ca component was considered to be in form of melted amorphous silicate, oxide and sulfate, in accordance with the element distribution analysis on the surface of ashes by SEM/EDX.It was found that coal slag has a reactivity for HィイD22ィエD2S capture at high temperature and the sulfidation reaction of coal slags was very rapid at early stage of reaction. The iron component, involved in coal slags, played a important role in sulfur capture. It was not observed that calcium component in coal slags showed reactivity with sulfur. It was clarified that the reactivity of coal slags with HィイD22ィエD2S was mainly influenced by the amount of Fe content on the surface of coal slag particle. The influence of temperature on the conversion of iron into sulfide was not clearly found in the range of 1123〜1273K.