Separation operations, multistage calculation methods

Flash vaporization and multistage distillation calculation methods have been shown to be adaptable to membrane separations, which indicates the degree of separation that can be achieved. Furthermore, the use of multistage or cascade operations enhances the sharpness of separation and can be used to separate components with low relative selectivity. 

What is often called the McCabe-Thiele method " for binary distillation calculations deploys a y-x (or y-x) diagram, say, for the more-volatile component, here designated the more-permeable component i. This furnishes substantiation that a separation can indeed be attained by the use of recycle or reflux in a multistage or cascade operation. 

As with the gas-liquid operations, liquid extraction processes are carried out in slagewise equipment which can be arranged in multistage cascades and also in differential-contact apparatus. We shall consider the methods of calculation and the nature of the equipment and its characteristics separately for each type. 

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