Ash chemistry aspects of straw and coal-straw co-firing in utility boilers

Conference · Thu Dec 31 04:00:00 EST 1998

OSTI ID:349133

Frandsen, F J; Nielsen, H P; Hansen, L A ^[1]; Hansen, P F.B.; Andersen, K H ^[2]; Soerensen, H S ^[3]

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1. Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Chemical Engineering
2. Midtkraft I/S Power Co., Skoedstrup (Denmark). Studstrup Power Station
3. Geological Survey of Denmark and Greenland, Copenhagen (Denmark)

Deposits formed in straw-fired grate-boilers showed significant amounts of KCl (40--80% (w/w)) and KCl-coated Ca-Si-rich particles. CFB co-firing of straw and coal caused deposits in the convective pass containing predominantly K{sub 2}SO{sub 4} (50--60% (w/w)) with small amounts of KCl close to the metal surface. In pulverized coal-straw co-fired boilers, deposits almost free of KCl were found. Most of the potassium in these deposits is derived from K-Al-Si-rich fly ash particles and the rest occurs as K{sub 2}SO{sub 4}. The presence of K-Al-Si-rich fly ash particles indicates that solid residue quality and reuse of fly ash in cement and concrete production rather than deposit formation may be of concern when utilizing straw in pulverized fuel boilers. This paper provides a review of Danish experiences with high-temperature ash deposit formation in the following full-scale utility boilers: Slagelse CHP (31 MWth), Haslev CHP (23 MWth) and Rudkoebing CHP (10.7 MWth), all straw-fired grate-boilers; Grenaa CHP (80 MWth), a coal-straw co-fired Circulating Fluidized Bed (CFB) boiler; and the Midtkraft-Studstrup Power Station, Unit 1 (380 MWth), a coal-straw co-fired PF-boiler.

• OSTI ID: 349133
• Report Number(s): CONF-980985--; ISBN 1-890977-15-2
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
09 BIOMASS FUELS
ASHES
BOILERS
CHEMICAL COMPOSITION
COAL
COCOMBUSTION
PERFORMANCE TESTING
STRAW
THERMAL POWER PLANTS