Selenium emission control at high temperatures with mineral sorbents. Final report, September 1, 1994--February 29, 1996
The focus of this project is on toxic metal removal by sorbent injection in the upper furnace and economizer sections of a coal- fired boiler. Selenium was chosen as the candidate heavy metal to be studied because of its high volatility and associated difficulties in removal. A thorough mechanistic investigation of the SeO{sub 2}-Ca(OH){sub 2} interaction at both medium and high temperatures has been conducted in this project. Experiments were performed in the two temperature ranges in the presence and absence of O{sub 2}; desorption studies were conducted to characterize the nature of interaction; and XRD/XPS and Ion Chromatography studies were performed for species identification. It was inferred from these findings that the selenium capture was significantly more in the medium temperature range (450-650{degrees}C) than in high temperature range (800-1000{degrees}C) and the captured selenium species in the medium temperature range is in the form of calcium selenite (CaSeO{sub 3}) and a reaction scheme was proposed for the CaO/SeO{sub 2} interaction: CaO (s) + SeO{sub 2} (g) = CaSeO{sub 3} (s). This reaction process does not require the participation of oxygen, as was confirmed by various analytical techniques and supported by the experimental evidence. Results of the high-temperature studies indicate much reduced capture at these temperatures with negligible selenium sorption above 900{degrees}C. This behavior was attributed to the decomposition of calcium selenite at higher temperatures.
- Research Organization:
- Ohio State Univ., Columbus, OH (United States)
- Sponsoring Organization:
- Ohio State Government, Columbus, OH (United States)
- OSTI ID:
- 419438
- Report Number(s):
- OCDO--97001484; ON: TI97001484
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
20 FOSSIL-FUELED POWER PLANTS
54 ENVIRONMENTAL SCIENCES
CALCIUM COMPOUNDS
CALCIUM HYDROXIDES
CHEMICAL REACTION KINETICS
CHROMATOGRAPHY
DEMETALLIZATION
EXPERIMENTAL DATA
FLUE GAS
PROGRESS REPORT
REMOVAL
SELENITES
SELENIUM
SORPTION
SORPTIVE PROPERTIES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
X-RAY DIFFRACTION