Thermodynamic and Kinetic Principles of Mass Transfer Separation Processes

Abstract

AbstractStarting from the definition of a separation process the need is shown for introduction of a separation concept which is independent of the mechanism of the process and of its boundary conditions. This concept has to be converted into hardware by the introduction of performance factors which depend on the process mechanism and hence on mass transfer kinetics. General equations for mass transfer are presented incorporating concentration, pressure, force and thermal diffusion. Examples of interaction of the different types of diffusion are presented for the separation of binary mixtures and this is followed by a more detailed consideration of special cases of concentration diffusion including a need for model formulation of interphase mass transfer. It is further shown that mass transfer processes can be intensified by thermodynamic methods (modification of equilibrium conditions) or by kinetic methods (introduction of a chemical reaction or change from continuum to molecular level of organisation of matter). Finally, it is shown that alternatives exist for process selection in which energy savings have to be balanced against increased plant complexity.