Modeling for combustion and sulfur retention efficiencies of fluidized-bed combustors
Studies on the combustion of coal and sulfur capture by limestone/lime particles are carried out analytically and verified with the experimental data reported elsewhere. Extensive experimental data are available for small scale fluidized-bed combustion (FBC). However, the usefulness of these data to large scale FBC is rather limited since the geometry and operating conditions are widely different from those of small scale FBC. The present work is concerned with the correlation of combustion efficiency, eta and sulfur retention efficiency, S/sub ret/ with a dimensionless group called Damkoehler number defined as a ratio of characteristic residence time to the reaction time. Essentially population balance equations and two phase reactor theory are used in developing the model for combustion and sulfur retention efficiencies of FBC. Simplifying assumptions are made for obtaining the results in terms of Damkoehler numbers. The mass balance equations of solid fuel particles, CaO particles, oxygen, and sulfur dioxide yield to the solutions to (i) oxygen and sulfur dioxide concentrations in the emulsion phase, (ii) dimensionless weight of solid fuel particles and CaO particles in the bed, (iii) burnt char fraction, (iv) burnt volatiles fraction, (v) CaO conversion efficiency to CaSO/sub 4/, (vi) combustion efficiency, and (vii) sulfur retention efficiency. Generalized plots are given for the weight of char, bed material, burnt char fraction, CaO conversion efficiency, and sulfur retention efficiency vs. Damkoehler numbers. These correlations are then verified with the experimental data for combustion and sulfur retention efficiencies reported in the open literature for FBCs operated under various conditions and widely varying geometrical parameters. The effects of attrition, fragmentation, swelling, and overflow are investigated.
- Research Organization:
- Texas A and M Univ., College Station (USA)
- OSTI ID:
- 6988030
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
010600* -- Coal
Lignite
& Peat-- Properties & Composition
ADSORPTION
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CALCIUM OXIDES
CARBONACEOUS MATERIALS
CARBONATE ROCKS
CHALCOGENIDES
CHEMICAL REACTIONS
COAL
COMBUSTION
COMBUSTORS
ENERGY SOURCES
FLUIDIZED-BED COMBUSTORS
FOSSIL FUELS
FUELS
LIMESTONE
MATERIALS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
ROCKS
SEDIMENTARY ROCKS
SORPTION
SULFUR COMPOUNDS
SULFUR DIOXIDE
SULFUR OXIDES
THERMOCHEMICAL PROCESSES