Examining Relationships Between Coal Characteristics and the Performance of TVA Power Plants. Final Report

摘要

An analysis of data from most TVA units (omitting Allen, Cumberland, and Watts Bar) showed that coal ash and moisture and boiler age had the greatest effect on boiler efficiency. The following relationship was derived for boiler efficiency for the TVA system as a whole: Boiler Efficiency = K -0.022 (Ash) - 0.100 (Moisture) -0.039 (Age). The constant K has a different value for each group of like boilers. Coal sulfur and boiler load were investigated as possible variables, but were not shown to be important statistically. The above model accounted for 91 percent of the variability in reported boiler efficiency values. Other relationships are reported for individual groups of identical boilers and for aggregates of similar boilers. For the TVA system as a whole, boiler availability relationship was defined, calculated and is given in the report. Over the range of ash fired at TVA plants (generally 12 to 24 percent), this relationship indicated that, for a typical plant, the outage hours may vary by 360 hours/year because of changes in ash alone. Likewise, over the range of sulfur values for TVA plants (generally 1.0 to 5.0), outage hours at a typical plant may vary by as much as 870 hours per year due to sulfur alone. Maintenance costs that were judged to be coal-related were studied to determine how maintenance costs varied with coal and other factors for each cost category and for each plant. Results are only reported for plants and equipment categories where the result was considered statistically significant; e.g., the correlation coefficient was equal to or exceeded the 90 percent confidence interval. An effort made to identify operating costs that might be coal-related led to conclusion. After examination of the available operating cost data, it was decided that it would not be worthwhile to expend much effort on analysis in this are. As a result of the study, a number of recommendations were made as regards TVA operations or data handling. (ERA citation 08:053861)