6 Vapour—liquid equilibrium at high pressure

Abstract

Publisher Summary It is impossible to perform vapor–liquid equilibrium (VLE) measurements at high pressure for all kind of systems, using one technique only; therefore, the authors have divided the experimental methods for the determination of high-pressure VLE into two groups based on the way the compositions are measured. This chapter makes a classification according to the way the phase equilibrium are obtained—that is, closed- and open-circuit methods. Closed-circuit methods can be divided into static-synthetic and static-analytic methods. These methods have the advantage that the system investigated can be equilibrated for a sufficient time-period, so that the equilibrium is assured. On the other hand, open-circuit methods involve a separator that permits collecting all the circulating phases in equilibrium. Equilibrium is attained during the circulation of a mixture. The major advantages of this method, also known as the “dynamic method,” are the short equilibration times and the possibility for use with nonmetallic materials.