A pilot scale adsorber apparatus was designed and constructed to investigate water and ethanol adsorption/ desorption kinetics on 3A zeolite for the design purposes of a fuel ethanol dehydration pressure swing adsorption (PSA) process. Equilibrium studies have shown that 3A zeolite adsorbed a significant amount of water while very weak ethanol adsorption was observed. The breakthrough curves were utilized to study the effects of column pressure, temperature, flow rate, pellet size, and adsorbate concentration on the overall mass transfer resistance. Based on experimentally observed trends, both macropore and micropore diffusion were identified as relevant mass transfer mechanisms. A mathematical model for a bench scale adsorption bed included the linear driving force (LDF) adsorption rate model and the variation of axial velocity. A detailed heat transfer model was a necessity since the bed dynamics was affected by heat transfer in the bed wall. The model was used to analyze the experimental data and extract values of pertaining diffusion coefficients.

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A certain class of refractory materials can be synthesized in the sintering or in the self-propagating regime by a direct reaction between the metal powder and carbon, boron, or silicon. A detailed analysis and modeling of such processes are given. Criteria are derived for stable, unstable, and degenerated combustion as well as approximate relations for the velocity of a constant-pattern profile, as a function of the heat-transfer coefficient. The approximate formulas are verified by a detailed numerical study. Different types of combustion (constant-pattern profiles, standing waves, and complex oscillatory behavior) have been observed.

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