Effect of fuel quality on slagging behavior in a cyclone-fired boiler
- Microbeam Technologies Inc., Grand Forks, ND (United States)
- BNI Coal Ltd., Center, ND (United States)
- Minnkota Power Cooperative, Inc., Center, ND (United States)
Relationships between the occurrence of poor slag flow episodes at a cyclone-fired boiler, coal mineral content, heating value, and other fuel quality parameters have been investigated. In addition, optimization of boiler operating conditions to match coal quality is the major emphasis of current activities. The boiler fires North Dakota lignite, a highly variable fuel, and experiences intermittent cyclone slagging problems related to coal quality. Cyclone slagging episodes were found to occur when the heating value of the fuel was less than 6600 Btu/lb and the T250 was greater than 2250 F. Higher-Btu coals burn hotter and appear to be able to handle higher T250 values without slagging. Other fuel quality parameters related to cyclone slag flow behavior include high silicon and aluminum concentrations and high concentrations of the silicon- and aluminum-rich clay minerals illite and montmorillonite. These minerals are thought to contribute to cyclone slagging episodes by reducing the ability of the slag to incorporate calcium, thus leading to increased slag viscosity. To improve slag flow behavior, operating conditions have been modified to maintain high temperatures in the cyclones. Changes include increasing coal drying temperature and balancing the air/fuel ratio. T250 can be readily calculated from coal ash composition. Clays and other minerals can be identified in individual coal particles using automated scanning electron microscopy with energy-dispersive X-ray spectrometry. Use of these analytical techniques can enable potential cyclone slagging problems to be predicted in advance.
- OSTI ID:
- 349059
- Report Number(s):
- CONF-980985-; ISBN 1-890977-15-2; TRN: IM9924%%59
- Resource Relation:
- Conference: 15. annual international Pittsburgh coal conference, Pittsburgh, PA (United States), 14-18 Sep 1998; Other Information: PBD: 1998; Related Information: Is Part Of Fifteenth annual international Pittsburgh coal conference: Proceedings; PB: [1500] p.
- Country of Publication:
- United States
- Language:
- English
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