The Sharp Interface Model:Zero-Order Reaction with Volume Change (original) (raw)
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Journal of Chemical and Petroleum Engineering (JChPE), 2021
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A rigorous multicomponent multi gassolid reaction model is developed. It is based on the particlepellet model and considers the transient nature of the system, interand intra-particle heat and mass transfer and the variation of structural parameters with reaction. The model equations describing the structural changes along with property evaluation schemes are formulated for a general multicomponent system. Simulation results are compared with experimental data for carbon gasification and the reduction of a nickel oxide / hematite mixture. The match between model and experiment was found satisfactory. Both concentration and temperature profiles and other parameters are examined. On a mis au point un modele de reactions gazsolides multiples a plusieurs composantes. II s'appuie sur le modele particules-pastilles et considere la nature transitoire du systeme, le transfert de chaleur et de matiere inter et intra-particulaire, ainsi que la variation des parametres structurels avec la reaction. Les equations de rnodele decrivant les changements structurels ainsi que les schemas d'evaluation des proprietes sont formulees pour un systeme a composantes multiples general. Les resultats des simulations sont compares aux donnees experimentales pour la gazeification du carbone et la reduction d'un melange oxyde de nickelihematite. L'accord entre le modele et I'experience s'est avere satisfaisant. Les profils de concentration et de temperature sont examines ainsi que d'autres parametres.
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Aiche Journal, 1993
In the context of gas-solid noncatalytic reactions, several models have been developed in the literature (for comprehensive reviews, cf. . This work focuses on the sharp-interface model (SIM), which can be used to describe, once incorporated into a suitable reactor model, a variety of chemical and metallurgical processes including the roasting of zinc sulfide and the combustion of coal . Under the assumptions of isothermal conditions, equimolar counterdiffusion of reacting and product gases and pseudo-steadystate approximation, an analytical relationship that provides the time required to reach the desired conversion of a single particle of the solid reactant can be derived in a straightforward manner for the case of a first-order reaction with respect to the gaseous reactant . The assumption of a first-order reaction, however, can be valid only over a limited range of conditions and may not even be true when the gaseous reactant is adsorbed strongly on the solid surface. A number of examples of nonlinear gas-solid noncatalytic reactions are reported in the literature (Cannon and Denbigh, 1957; Habashi, 1969; Chu and Rahmel, 1979). For nonlinear kinetics, the conversion of the solid reactant as a function of time has to be computed numerically, as shown by Sohn and Szekely (1972) for power-law kinetics and by Ramachandran (1982) for Langmuir-Hinshelwood (L-H) kinetics.