Model for drying during fluidized-bed combustion of wet low-rank coals
✍ Scribed by Pradeep K. Agarwal; William E. Genetti; Yam Yee Lee; Shyam N. Prasad
- Publisher
- Elsevier Science
- Year
- 1984
- Tongue
- English
- Weight
- 824 KB
- Volume
- 63
- Category
- Article
- ISSN
- 0016-2361
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✦ Synopsis
An unsteady state heat conduction model with a convective boundary condition is proposed for the drying of low-rank, high-porosity coals, such as Iignites, during fluidized-bed combustion. The drying front is assumed to be the receding surface of a wet core. The solution technique for this moving boundary problem is based on the heat balance integral approach with immobilization of the moving boundary by a change in space variable. The governing cubic equation describing the drying curve in dimensionless form may be solved easily by the Newton-Raphson method. The model predictions are compared with experimental data for Mississippi lignite with excellent agreement. A correlation for estimation of total drying time is proposed. The temperature profiles obtained may be used forthe study of the coupled drying and devolatilization in fluidized-bed combustors. The profiles could also be of importance in the study of formation of fissures/cracks in lignites subjected to intense heating conditions encountered during fluidized-bed combustion.