OCR Text |
Show A problem is encountered in trying to use this parameter because ash fusion temperature measurements are not always carried to the fluid temperature. Various ash fusion temperature furnaces are limited to 2600, 2700, or 2800 F. If all of the ash fusion points are not reached by the time the furnace reaches its limiting temperature, the values are reported as 2600+, 27U0+, or ^800 F. Thus, the temperature differences needed for this calculation cannot always be calculated precisely. For example, if the initial deformation temperature and the fluid temperature are both reported as 2600+ h, the temperature range is not known. Also, the reproducibility of the ash fusion measurements is not good: 100 F for fluid temperature in an oxidizing atmosphere and 125 F for (3) initial deformation temperature in reducing atmospherev . Thus, the reported difference between these two temperatures can vary as much as 225 F for a given ash. As typical values for the temperature range may only differ by about 500 F, the 225 F possible uncertainty in the value can represent nearly 50 percent of the calculated value. Finally, a number of plants did not report oxidizing ash fusion temperatures. Thus, for the temperature range examined here, the temperature difference was taken to be that between the fluid temperature, reducing, and the initial deformation temperature, reducing. Nevertheless, Figure 5 shows the data obtained on this project as plotted against the ash fusion temperature range (as defined above) and the unit area steam generation rate. Due to the problems described above, the separation on Figure 5 between units with different frequencies of slagging is somewhat poorer than for the other slagging parameters. Discounting those units for which the temperatures range calculates as zero, and using the boundaries as drawn, only 54 percent of the power plants are categorized correctly. FOULING PARAMETERS FOR BITUMINOUS COAL This section describes the evaluation of fouling parameters for bituminous coals, based on parameters have been reported in various literature. 1-9 |