OCR Text |
Show Table 3 shows that for initial deformation, temperatures of the ashes are 2000, 2220 and 2310°F for Indiana, Ohio, and West Virginia coals, respectively. Note that when the temperatures in an operating furnace are such that the ash particles have cooled to a temperature lower than their initial deformation temperature, they tend to accumulate as a dry product. Thus, these ash fusion temperatures provide information on the relative tendency of ash particles to stick together or build up slowly on heat-absorbing surfaces during passage through the furnace, depending on furnace operating conditions. Data in Table 3 indicate that the severity of the fire-side deposit problems of the test coals will decrease from Indiana to Ohio to West Virginia coals, in that respective order. Burning Profiles Comparative burning profiles of the micronized and parent Indiana, Ohio, and West Virginia coals are shown in Figures 3, 4 and 5, respectively. The small peak for each sample centered at about 212°F represents a loss of residual moisture. The remaining peaks represent oxidation of the sample. As shown, the ignition and burnout temperatures of micronized coals are lower than the respective parent coals. Improvement in performance is attributed to the increased surface area of the smaller particles. The increased surface area provides higher number of reactive sites that are readily accessible to oxidation and consequently improve combustion performance. Data in Figures 3, 4 and 5 indicate that combustion performance of the test coals should decrease from Indiana to Ohio to West Virginia coals. 9-13 |