Chemical and physical analyses of Tidd hot-gas filter ash
- Univ. of North Dakota, Grand Forks, ND (United States). Energy and Environmental Research Center
The American Electric Power Tidd pressurized fluidized-bed boiler operated from Oct 1992--Mar 1995. In trials employing the Westinghouse advanced particle filter (APF), ash bridges formed between candle filters, in some cases causing filter breakage. In later tests, the sorbent and equipment upstream of the APF was modified, and bridging was greatly reduced. The authors are performing chemical and physical analysis of the ashes to quantify the changes in the ash that led to the reduction in bridging. Analyses include advanced techniques such as quantitative scanning electron microscopy to determine the composition and size distributions of ash particles down to 0.1 micron diameter and high-temperature tensile strength testing. The biggest changes in ash behavior in the Tidd APF are related to system operation, such as spoiling of the cyclone upstream of the APF. When the cyclone was completely spoiled during the February and May 1995 testing, much larger ash particles entered the APF. These larger particles differed in composition from the APF ash samples collected in May and October 1994. Also, the removal of fines from the sorbent caused an increase in average particle size entering the APF. Differences in the May 1995 ashes relative to location in the APF are greater amounts of magnesium and less silicon and aluminum in the ashes from the filter collars, which are static areas. The magnesium likely originates from the sorbent while the silicon and aluminum originate from the coal ash, indicating possible particle-size variations in the different deposits. In addition to particle size, the age of the deposits is reflected in their compositions. The bridged deposits contain more sulfur than the other filter cakes, indicating that they may have been present in the filter vessel longer than the other samples. It may also indicate that sulfur may be a factor in causing hard deposits which may force filters apart and cause filter failure.
- Sponsoring Organization:
- USDOE Morgantown Energy Technology Center, WV (United States); Electric Power Research Inst., Palo Alto, CA (United States)
- OSTI ID:
- 504609
- Report Number(s):
- CONF-960954--
- Country of Publication:
- United States
- Language:
- English
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