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Show RESULTS AND DISCUSSIONS 1.Chemical and Physical Analysis Table 3 shows the properties of the EP dust comparing with these of bi t urn i nous and semi ant hraci te. Volati le matter content of the EP dust is as smal I as semianthracite, while the heating value is similar to that of bituminous which is usually used in coal-fired boilers. The asphalt-fired EP ash has much sulfur and relatively large amount of ash extremely rich in vanadium. Nitrogen content is about a half of that in bituminous. Table 4 shows the bulk specific gravity and the specific surface area for the asphalt-fired EP ash and pulverized coal. Also, figure 4 shows the SEM photograph of EP dust. 11 is obvious from them that the dust particles have the porous structure. 2.Laboratory-scale testing Figure 5 shows the results of differential thermal analysis for EP dust, bituminous coal and semianthracite. In the figure, curves of TG, DTG and DTA represent thermogravimetric analysis, derivative thermogravimetric analysis and differential thermal analysis, respectively. As for the bituminous coal, i t shows the following behavior: a loss of water at around 100°C, an exothermal reaction wi th increase in weight by absorbing oxygen up to around 350°C, release of volatile matter at around 390°C, combustion of residuals, and burning out almost at 610°C. Similar behavior is observed for the semianthracite, though the primary oxidization and the release of volatiles are not so active as the bituminous coal. Also the burn out temperature is higher, nearly at 700°C. There is almost no primary oxidization up to around 400°Cas noted by DTG and DTA, however an abrupt and rapid oxidization occurs from that temperature. Accordingly, it burns out at not more than 580°C. From these results, it is confirmed that the EP ash has the excellent combustion and burn out properties when the temperature is higher than 400°C. Figure 6 shows the burn-out profiles obtained in the drop tube furnace. In the figure, the burn-out rate (r|) is defined by : |
