Fundamental heat transfer processes packed

Fig. 12 - Fundamental heat transfer processes occurring within a packed bed [is]...

The variation of efficiencies is due to interaction phenomena caused by the simultaneous diffusional transport of several components. From a fundamental point of view one should therefore take these interaction phenomena explicitly into account in the description of the elementary processes (i.e. mass and heat transfer with chemical reaction). In literature this approach has been used within the non-equilibrium stage model (Sivasubramanian and Boston, 1990). Sawistowski (1983) and Sawistowski and Pilavakis (1979) have developed a model describing reactive distillation in a packed column. Their model incorporates a simple representation of the prevailing mass and heat transfer processes supplemented with a rate equation for chemical reaction, allowing chemical enhancement of mass transfer. They assumed elementary reaction kinetics, equal binary diffusion coefficients and equal molar latent heat of evaporation for each component. 

In spite of the major economic importance of these operations, the fundamental aspects of flow patterns and heat and mass transfer in these systems have received very much less attention than for the case of beds and fluidized beds which were discussed in the preceding sections. This scarcity of information necessarily limits the material that can be presented here indeed the treatment of gas-solid reaction systems in kilns, moving beds, and cyclones will be based on the real (or assumed) analogy of these operations to packed-or fluidized-bed processing. 

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