Stagewise processes

Fig. 1. The analogy between the separation stage and the transfer unit or equivalent theoretical plate (a) ia a stagewise process (b) ia a...

Henley, E. J. and H. K. Staffm, Stagewise Process Design, John Wiley Sons Inc, New York (1963). 

Mass transfer processes involving two fluid streams are frequently carried out in a column countercurrent flow is usually employed although co-current flow may be advantageous in some circumstances. There are two principal ways in which the two streams may be brought into contact in a continuous process so as to permit mass transfer to take place between them, and these are termed stagewise processes and continuous differential contact processes. 

Ingham, J. and Dunn, I. J. (1974) Digital Simulation of Stagewise Processes with Backmixing. The Chem. Eng., June, 354-365. 

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