OCR Text |
Show 4 2.3 Features of melting furnace The shape of the furnace was determined on the basis of our experience and heat flow analysis. It has been designed so as to ensure through melting and separation of the ash and complete combustion of the pyrolytic gas by favorable swirl-flow. Fig.2 shows one of the results of the heat flow analysis. The pyrolytic gas including dust flows into the primary combustion region of the melting furnace along the tangential direction, swirls and burns. The melted ash is captured on the wall surface. The combustion gas is accelerated after passing the throttle and strikes against the bottom of the slag separation region, where fine slag, which has not been captured on the wall surface, is separated by collision and led to the slag output port. In this furnace, high temperature complete combustion is performed and a high temperature atmosphere is held for a long time. Consequently, the precursors of dioxins, etc. are decomposed. In addition, copper, which serves as a catalyst for recomposition, is melted and separated. Therefore, this technique can be used to prevent the recomposition of dioxins. 3. Experiments using a pilot plant A pilot plant with a capacity of about 2 tons/day, having a fluidi zed-bed pyrolysis furnace and a swirl-flow melting furnace as its basic installations, was used to cl ari f y the py rol yti c and mel ti ng characteri sti cs of muni ci pal sol i d waste and to obtain process data. 3.1 Outline of the pilot plant Fig.3 shows the system flow and Photo. 1 shows the external view of the pilot plant. The temperature of the primary air of the pyrolysis furnace can be adjusted using an electric heater. The waste feeding system consists of a double ball valve for sealing and a weighing machine for the fed waste. The pyrolysis furnace and the melting furnace are directly connected through a duct. It is possible to bypass the melting furnace for test purposes. The slag discharged from the melting furnace is stored in the slag pot and extracted in one batch |