Increase in Ash Loading by Adding Slag-Bed Furnace to Swirl Flow Coal Ash Fusing Furnace

Abstract

To utilize coal ash slag as aggregate, coal ash has to be completely-fused and recovered as amorphous granulated slag, same as granulated blast furnace slag. We designed the new coal ash fusing furnace consisting of two chambers to increase ash load and to inhibit the recovery of incompletely-fused slag. The upper chamber is the existing vertical cylindrical furnace and the lower chamber is the new horizontal furnace. In the upper chamber, coal ash is transferred near the inner wall by centrifugal force, and is trapped at the surface of fused slag, and then flow down to the lower chamber. When the ash load of the upper chamber increased, the rate of amorphous slag content decreased because of increasing incompletely-fused slag. To enhance heating, the lower chamber which has some burners was installed just below the upper chamber. In the lower chamber, what is called slag-bed furnace, the incompletely fused slag is fused completely during flowing down onto the bottom of the furnace. Then, we designed the new coal ash fusing furnace, the inner diameter of upper chamber was 0.6 m and the length of lower chamber was 1.8 m. We verified that to recover 100 % amorphous slag content at the ash/coal (kg/kg) ratio 4.6, the necessary fuel quantity of the furnace was 30 kg/h coal and 5.87 m 3 N/h LPG. Accordingly, the effect of slag-bed furnace to increase ash load was confirmed.