ABSTRACT

The various staged operations taken up in the previous chapter have several features in common. The two phases involved in the transfer of mass were brought together and mixed intimately in discrete stages, which took the form of stirred tanks or some equivalent device. As a result, the concentrations were generally distributed uniformly in space and any variations they underwent were with respect to time, and not with distance. The operations were not only allowed to go to equilibrium but were actively encouraged to do so by means of agitation and the provision of sufficient contact time. Any departures from equilibrium were lumped into an entity called the stage efficiency. An efficiency of 100% signified the attainment of complete equilibrium, and values below that expressed varying degrees of nonequilibrium.