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Show Sintering Test. The strength of the sintered fly ash from micronized coal tests was greater than the strength of the sintered fly ash from the pulverized coal tests. The sintering test provides information regarding the tendency of eastern coal fly ash to sinter and form a strong bonded mass on the tube, and in turn, hinder the performance of sootblowers in full-scale boilers [9, 10, 11], Over the years, B_W has developed correlations between the sintering strength and the potential of ash to foul superheaters. These correlations were for burning pulverized coal and may not be directly applied to evaluate the effect of sootblowers on the removal of ash deposits of micronized coals from the tubes. This is because ash buildup rates are significantly different, and sintering time/temperature relationships are different. Data from sintering tests are presented in Table 6. Based on relationships between sintered strength of fly ash and the superheater fouling potential for eastern pulverized coals, the expected fouling potential of each pulverized coal sample is presented. As shown, the strength of sintered fly ash for Indiana micronized coal is greater than Indiana pulverized coal. The result probably is a consequence of finer fly ash particles of micronized coal as compared to the fly ash from pulverized coal. The superheater fouling potential of Indiana pulverized coal is expected to be high. Data show that the sintered strength of both micronized and pulverized coals increases as expected with an increase in sintering temperature. Similar results were observed with Ohio and West Virginia coals; however, there were significant differences. The strength of sintered fly ash of both micronized coals are significantly greater than for the respective pulverized coals. These may be due to significant differences in the particle sizes of the fly ash from micronized coals. The increase in sintered strength with the increase in sintering temperature is mild. The fouling potential of both Ohio and West Virginia pulverized coals is expected to be moderate. 9-38 |