Freeboard reactions in fluidized coal combustion

Technical Report · Fri May 11 04:00:00 EDT 1984

OSTI ID:6078970

Walsh, P M; Dutta, A; Beer, J M

The objective of this study was to determine the contribution of freeboard combustion to overall fixed carbon conversion during atmospheric pressure fluidized bed combustion of Kentucky No. 9 high volatile bituminous coal. The progress of the O/sub 2//char reaction in the freeboard was inferred from O/sub 2/ profiles determined by gas sampling. The rates of O/sub 2/ consumption were in good agreement with the O/sub 2//char rate expression of Sergeant and Smith (1973), except at the lowest temperature investigated (964 K). The discrepancy in this case might be due to catalysis of the O/sub 2//char reaction by lime, since this was the first run of the series. Extrapolation of the O/sub 2/ profile to the bed surface using the rate expression of Sergeant and Smith showed that approximately all of the fixed carbon conversion could be accounted for by freeboard combustion. A simple model is proposed in which devolatilization, fragmentation, attrition, and volatile combustion are limited to the bed; with combustion of the finely ground char occurring only in the freeboard. This model predicts O/sub 2/ at the combustor outlet within 60% of the measured values, except in the low temperature/high lime case.

• Research Organization: Massachusetts Inst. of Tech., Cambridge (USA)
• DOE Contract Number: FG22-80PC30215
• OSTI ID: 6078970
• Report Number(s): DOE/PC/30215-10; ON: DE85007741
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
014000* -- Coal
Lignite
& Peat-- Combustion
CARBONACEOUS MATERIALS
CHARS
CHEMICAL REACTIONS
COAL
COMBUSTION
ELEMENTS
ENERGY SOURCES
FLUIDIZED-BED COMBUSTION
FOSSIL FUELS
FUELS
MATERIALS
MATHEMATICAL MODELS
NONMETALS
OXIDATION
OXYGEN
PYROLYSIS PRODUCTS
TEMPERATURE EFFECTS
THERMOCHEMICAL PROCESSES