ABSTRACT

Multistage phase separation processes operate on the principle that when binary or multi-component mixtures form two or more phases at equilibrium with each other, each phase generally has a distinct composition. If, for example, a multi-component vapor mixture is at equilibrium with a liquid phase, the vapor will, in general, be richer in the lighter components than the liquid, whereas the liquid will be richer in the heavier components. Thus, if one desires to separate a given feed stream into lighter and heavier components, a step in the right direction would be to bring the stream to such temperature and pressure that would result in the formation of two phases-a vapor and a liquid, then to separate the two phases in a flash drum. As a closer look will indicate, however, the separation power of a single equilibrium stage is rather limited.