Continuous-contact operations

Continuous-contact operations are diametrically different in almost every aspect. The two phases are in continuous flow and in continuous contact with each other, rather than repeatedly separated and recontacted in an array of stages. Second, the attainment of equilibrium is shunned. An active driving force is maintained at all times, and its constituent concentrations vary continuously from the point of entry to the exit. The result is that the concentrations are now distributed in space and, assuming a normal steady-state operation, are invariant in time. Thus, while staged operations vary at most with hme, but not at all with distance, the exact opposite holds in continuous-contact operations. 

In the following, we divide continuous-contact operations into two distinct categories. The first deals with classical packed-column operations in counter-current flow. We revisit the packed-gas scrubber we first saw in Chapter 2 and provide a general survey of packed-gas absorption operations. Packed-coliunn distillation and liquid extraction are addressed next, and in a somewhat imusual departure from the norm, we reexamine cc fee decajfeimtion by supercritical extraction. The process involves a moving-bed configuration. 

Mass Transfer and Separation Processes Principles and Applications 

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Chapter 6 deals with phase equilibria, which are mainly composed of topics not generally covered in conventional thermodynamics courses. These equilibria are used in Chapter 7 to analyze compartmental models and staged processes. Included in this chapter is a unique treatment of percolation processes, which should appeal to environmental and chemical engineers. Chapter 8 takes up the topic of modeling continuous-contact operations, among which the application to membrane processes is given particular prominence. Finally, in Chapter 9 we conclude the text with a brief survey of simultaneous mass and heat transfer. 

Equation S.lle is the equivalent of the z = HTU x NTU relations established for other continuous contact operations the square bracket representing the NTU. It serves the same dual purpose of column design and performance (i.e., calculation of C /C ). It also allows us to predict the effect on performance of such parameters as air velocity, inlet concentration, or that of the partition coefficient m. 

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