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Type of Document	Dissertation
Author	Chang, Karl Kho-Chung
URN	etd-08092006-145027
Persistent URL	http://resolver.caltech.edu/CaltechETD:etd-08092006-145027
Title	Calcium-ion exchange of coal for retention of sulfur during combustion
Degree	PhD
Option	Chemical Engineering
Advisory Committee	Advisor Name Title George R. Gavalas Committee Chair Richard C. Flagan Committee Member William Harrison Corcoran Committee Member
Keywords	none
Date of Defense	1985-01-07
Availability	restricted
Abstract The kinetics of calcium-ion exchange of coal and the combustion of calcium-exchanged coals in a laminar flow furnace were investigated. Particle diffusion was found to be the rate-determining step for the process of ion exchange. A diffusion model gave good agreement with observed rates of ion exchange. Diffusion of ions in PSOC 680, a bituminous coal, was observed to be much slower than in PSOC 623, a lignite. Retention of sulfur during combustion of calcium-exchanged coals was observed to increase with increasing particle residence and oxygen concentration in the combustion gas. Chemical reaction was found to be the rate-determining step in the capture of SO2 by CaO in coal ash. The results of this study were interpreted in a proposed mechanism for the release and capture of SO2.
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