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Show Initial f~sibility tests were conducted with a spectrophotometer at Salem Harbor #1 in November, 1989. The resulting measurements showed that a strong signal could be obtained which was free of interferences over the range of wavelengths specified for a commercial instrument. These data were then used to design and build the prototype OTM. The first test series using the prototype OTM was conducted at Salem Harbor #3. This testing was successfully carried out and comparison to suction pyrometry measurements at the same location showed excellent agreement. The next test at Salem Harbor #3 was performed as part of an effort to characterize the slagging behavior of two coals, and make recommendations concerning coal quality effects on furnace performance. The OTM testing was performed in conjunction with furnace gas composition measurements, furnace observations, slag sampling, and laboratory work. The OTM operated successfully, and was able to display FEGT variations due to coal type, sootblowing events, and boiler load. The final tests at Salem Harbor #3 were executed to display the long term performance of the instrument. The instrument was set up and left on site for 5 weeks. The instrument was checked every week and no problems in operation or data quality were observed. The most recent, perhaps most extensive series of tests were performed in May of 1991 on eastern coals at Brayton Point #2 and #3. The two additional test sites represent two new boiler types, opposed wall and tangentially fired. During this test period, the effect of sootblower operation, in terms of frequency and location, was observed and suggestions were made for improving sootblowing practice based on the OTM results. For a second time, OTM measurements were successfully tested against suction pyrometry measurements. 3.2 Results at Salem Harbor #3 in November 1990 Some of the results from the tests at Salem Harbor #3 in November 1990 will be presented to illustrate the type and usefulness of data gained using the OTM. Figure 2 contains a diagram of Salem Harbor #3 with the OTM location relative to the sootblowers on the unit. At Salem Harbor #3, the OTM was located on the 7.5 level on the North side wall. Thus, the temperature was measured just prior to entering the superheater region. The main objective of this testing was to determine the slagging and fouling behavior of a new coal compared to a standard coal fired by NEP. The program included laboratory testing and a full scale test bum of both coals. A brief summary of the properties of the two coals to be compared is given in Table 2. The baseline coal appeared to have very good slagging characteristics with 9.4 % ash. The Pocahontas coal had a much lower ash fusion temperature, but also a lower ash content of 5.5 %. Because of the similarities in the combustion characteristics and conflicts in the fusion characteristics, a test bum of the two coals was planned to compare their slagging behavior at Salem Harbor Station. In addition to conventional analyses, the mineral matter in and the ash resulting from the combustion of Pocahontas coal were analyzed with computer controlled scanning electron 5 |
