Mineral, sorbent and sulfur interactions in real-scale CFBC
- VTT Chemical Technology, Espoo (Finland). Aerosol Technology Group
- Univ. of Gent (Belgium). Inst. for Nuclear Sciences
- Univ. of Kentucky, Lexington, KY (United States)
The interactions of mineral particles, sorbent limestone and sulfur were studied at an 80 MW{sub th} operating circulating fluidized bed combustion (CFBC) unit. The fuel was a Venezuelan low sulfur bituminous coal and a limestone sorbent was used for sulfur capture in the bed. Experiments were carried out to determine the fly ash particle size distributions as well as calcium and sulfur molar ratios as a function of particle size upstream of the electrostatic precipitator (ESP) at the flue gas temperature of 125 C with Berner low-pressure impactors (BLPI) and cyclone precutters. Samples were collected from the feed coal, limestone sorbent, the ESP collected fly ash and the boiler bottom ash. The compositions and size distributions of these samples were determined by computer controlled scanning electron microscope (CCSEM) and sieving methods. The fly ash particle mass size distribution was found to be unimodal with the mode at 20 {micro}m as determined with low-pressure impactors and cyclones. The ash and sorbent particles were found to form loose agglomerates in the CFBC. The agglomerate particles consisted of iron or calcium in association with silicate and aluminosilicate minerals. No signs of chemical reactions were found between ash particles and sorbent limestone indicating the agglomerate formation to be a purely physical process. Organically bound magnesium was found to react with aluminosilicate minerals, presumably inside the burning char particle. The Ca/S molar ratios in the fly ash increased with increasing particle size as a result of the existence of unreacted limestone particles and the uncompleted sulfation reaction due to the product layer diffusion control. The ratio Ca/S was significantly lower in the bottom ash, 3.1, than in the fly ash, 6.3, probably due to the longer residence times of the bottom ash particles in the furnace.
- OSTI ID:
- 287975
- Report Number(s):
- CONF-950522-; ISBN 0-7918-1305-3; TRN: IM9639%%595
- Resource Relation:
- Conference: 13. international conference on fluidized-bed combustion, Orlando, FL (United States), 7-10 May 1995; Other Information: PBD: 1995; Related Information: Is Part Of 13. international conference on fluidized bed combustion: Proceedings. Volume 2; Heinschel, K.J. [ed.] [Air Products and Chemicals, Inc., Allentown, PA (United States)]; PB: 823 p.
- Country of Publication:
- United States
- Language:
- English
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