A New Test System for Distillation Efficiency Experiments at Elevated Liquid Viscosities: Vapor–Liquid Equilibrium and Liquid Viscosity Data for Cyclopentanol + Cyclohexanol

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 on the basis of 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 the nonrandom 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 the Andrade equations, in order to precisely represent the nonlinear 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.

Isobaric Vapor–Liquid Equilibrium for the Binary Mixture of 1-Butanol + Butyl l-Lactate at 1 and 5 kPa

“…Schematic diagram of the Fischer Labodest VLE 602 apparatus: (1) valve of pressure equilibrium to the liquid-phase sample; (2, 5) ventilation valve; (3) outlet valve for the liquid sample; (4) valve of pressure equilibrium to the vapor-phase sample; (6) outlet valve for the vapor sample; (7) discharge valve; (8) sample tube liquid phase; (9) sample tube vapor phase; (10) solenoid: liquid sample, flow controller; (11) solenoid: vapor sample, flow controller; (12) electrical immersion heater; (13) liquid temperature sensor; (14) vapor temperature sensor; (15) temperature control of the heated tube, condensed vapor reflux; (16) temperature control of the heated isolation jacket; and (17) mixing chamber with a stirrer bar …”

Isobaric Vapor–Liquid Equilibria and Extractive Distillation Process Design for Separating Methanol and Methylal

“…However, DMF has higher toxicity and is much more expensive than the other three entrainers. Cyclohexanol has high selectivity and its viscosity decreases with the increase of temperature within a certain temperature range . Therefore, cyclohexanol is selected as the entrainer for separating methanol and methylal in this paper.…”

Separation Efficiency Measurements with Non‐Volatile Components and Elevated Feed Viscosities

“…For viscosities of up to 6 mPa s significantly decreased separation efficiencies have been observed with these mixtures [3][4][5]. However, higher viscosities are unlikely to be reached with binary mixtures [2,4,11,12]. Therefore, adding a viscosityenhancing non-volatile polymer seems to be reasonable.…”

“…Common test mixtures, however, are inviscid as they consist of organic solvents or water 10 and show viscosities of less than 1 mPa s at separation conditions 4. To reach higher feed viscosities, novel binary test mixtures have been proposed by Bradtmöller and Scholl 11 as well as Manivannan et al 12. For viscosities of up to 6 mPa s significantly decreased separation efficiencies have been observed with these mixtures 3–5.…”