A mathematical model is developed to describe the process of thermal regeneration in diesel-particulate monolithic filters. The model shows that a typical regeneration cycle consists of four stages: preheating, ignition, transportcontrolled combustion, and cooling. The total regeneration time and the peak temperature are the important regeneration characteristics and can be controlled by initial particulate loading, total filtration area, and channel wall thickness.

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Vapors of alkali metal compounds can be removed from coal combustion and gasification flue gases using high-temperature aluminosilicate sorbents. The fundamentals of alkali adsorption on kaolinite, bauxite, and emathlite are compared and analyzed both experimentally and through theoretical modeling. The results show that the process is not a simple physical condensation, but a complex combination of diffusion and reaction. The kinetics of adsorption on these sorbents have similarities: the process is diffusion-influenced, the rate decreases with time, and there is a final saturation limit. There are, however, differences in reaction mechanisms leading to potentially different applications for each sorbent. In adsorbing alkali chloride vapors, kaolinite and emathlite release all the chlorine back to the gas phase while bauxite retains some of the chlorine. Moreover, the products of reaction with emathlite have a melting point significantly lower than those for kaolinite and bauxite. Therefore, emathlite is more suitable for lower-temperature sorption systems downstream of the combustors / gasifiers, while kaolinite and bauxite are suitable as in-sito additives.

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Emission of cadmium compounds is a major problem in many combustors and incinerators. In the present work, the use of solid sorbents for removal of cadmium compounds from high-temperature flue gases is investigated. The sorbents tested were silica, alumina, kaolinite, emathlite, and lime. Compounds containing aluminum oxide show high cadmium removal efficiency. In particular, bauxite has the highest rate and capacity for cadmium capture. The overall sorption process is not just physical adsorption, but rather a complex combination of adsorption and chemical reaction.