Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Most of the distillation efficiency correlations that have been published thus far were developed or validated based on efficiency data at liquid viscosities less than 1 mPa.s. However, distillation with liquid viscosities greater than 1 mPa.s is encountered, in certain cases, in the chemical process industry. To study the effect of liquid viscosity on distillation efficiency at greater than 1 mPa.s, standardized test systems with elevated liquid viscosities at typical distillation conditions are required. To meet this objective, a new test system, cyclopentanol/cyclohexanol, was chosen based on a comprehensive set of search criteria. For this test system, vapor-liquid equilibrium data were collected from 2 to 101.3 kPa and modeled with non-random two-liquid (NRTL) model. In addition, liquid viscosity data were measured from 303.15 to 373.15 K and modeled with the modified forms of Andrade equations, in order to precisely represent the non-linear dependence of liquid viscosity with temperature and composition. This test system will help study the effect of liquid viscosity on distillation efficiency from 1 to 5 mPa.s. Subsequent investigations on the effect of liquid viscosity on separation efficiency of distillation columns with trays are enabled. 1. Introduction Distillation is the most widely used separation method in the chemical process industry with over 40,000 columns operating worldwide.1 The first step in designing a distillation column is the calculation of the number of theoretical stages. With the availability of rigorous models incorporated in the computer-aided design packages, the theoretical stage calculation can be readily accomplished.2 The next step is to calculate the number of actual stages with the use of the distillation efficiency correlations. The accuracy of distillation efficiency correlations is an important factor in the design of distillation columns. An underprediction of distillation efficiency