AbstractIsothermal vapor‐liquid equilibrium data for propane‐isobutane, a system of industrial importance, have been obtained in two pieces of apparatus at temperatures from 20° to 250°F. Over this temperature range, propane‐isobutane form ideal solutions. The paper discusses the sampling errors which occur in volatile systems.

Abstract High‐pressure isothermal vapor liquid equilibrium data were measured for the propane‐1‐propanol system at 81.6, 105.2, and 120.1° C in a static equilibrium cell with liquid‐phase sampling by a piston‐driven sampling rod and homogenizing the sample with a static jet mixer. The vapor phase was sampled by releasing it into an evacuated manifold, and the gas chromatograph was calibrated with a new variable volumetric device. Satisfactory modeling was achieved with the combined method (Wichterle, 1978b) using the UNIQUAC equation with equations of state: the group contribution EOS (Skjold‐Jorgenson, 1986), Peng‐Robinson EOS (Peng Robinson, 1976) or the two‐parameter Virial EOS. Differences between the measured and calculated vapor‐phase mole fractions, however, were signficant for the lower pressure regions of the 81.6 and 120.1° C isotherms. UNIQUAC parameters a ij , hitherto unavailable, with fairly strong temperature dependence in the 81.6 to 120.1° C range are proposed for the system. The covariance matrix indicated a significant correlation among the parameters. The classical mixing rule interaction parameters, σ ij , required for the original Peng‐Robinson EOS in the combined method were obtained using the direct method (Wichterle, 1978a) and were temperature‐independent for the isotherms for which the propane was supercritical. The possibility of propane/1‐propanol immiscibility was theoretically examined according to the criteria of Baker et al. (1982). The plots of Gibbs energy of mixing vs. phase mole fractions did not indicate liquid‐phase splitting, but the inferences are EOS‐dependent and must await visual confirmation. Our earlier vaporphase thermodynamic consistency test (1991a) indicated the data for all three data sets not to be inconsistent.

Abstract Isothermal vapor liquid equilibrium (VLE) data of the alternative 2,3,3,3-tetrafluoroprop-1-ene + 1,1,1,2-tetrafluoroethane + propane ternary mixture over the temperature range of 283.15–323.15 K at 10 K intervals were measured using a circulation type apparatus. The experimental VLE data were correlated by Wilson-RK model, NRTL-RK model and PR-WS-MUNIFAC model. All of the models can well present the experimental data. The average absolute relative deviation (AARD) of pressure are within 0.60% and the maximum average absolute deviation (AAD) of vapor mass fraction is 0.0154 for the PR-WS-MUNIFAC model. Based on the UNIFAC (Dortmund) method, the two new functional groups of C2H2F and CH2F were divided and the relevant group parameters were obtained by fitting the experimental data.

Abstract This study reports a set of new vapor liquid equilibrium (VLE) data for the binary mixture of 1,1,1,2-tetrafluoroethane (R134a) + propane (R290) at temperatures from 253.15 to 303.15 K, and the saturated vapor pressures of R290 and R134a at temperatures ranging from 253.15 to 323.15 K using a recirculation apparatus with view windows. The VLE data were correlated with the well-known NRTL-RK, Wilson-RK, and UNIQ-RK models. The results indicated that all the models showed good agreement with the experimental data. The average absolute relative deviations of pressure (AARDp) were between 0.01% and 0.02%, while the average absolute deviations of vapor phase mole fraction (AADy) were between 0.0035 and 0.0041. Positive azeotropic behavior could be observed for the R134a + R290 system, and the azeotropic point data at six temperatures from 253.15 to 303.15 K were presented.

essentially governed by Raoult and Dalton's laws, and assume that vapor–liquid equilibria are attained. Raoult's law states that the vapor pressure of a solution Distillation, also classical distillation, is the process of separating the component substances of a liquid mixture of two or more chemically discrete substances by selective boiling of the mixture and the condensation of the vapors in a still. Distillation can operate over a wide range of pressures from 0.14 bar (e.g., ethylbenzene/styrene) to nearly 21 bar (e.g., propylene/propane) and is capab Distillation, also classical distillation, is the process of separating the component substances of a liquid mixture of two or more chemically discrete substances by selective boiling of the mixture and the condensation of the vapors in a still. Distillation can operate over a wide range of pressures from 0.14 bar (e.g., ethylbenzene/styrene) to nearly 21 bar (e.g., propylene/propane) and is capable of separating feeds with high volumetric flowrates and various components that cover a range of relative volatilities from only 1.17 (o-xylene/m-xylene) to 81.2 (water/ethylene glycol). Distillation provides a convenient and time-tested solution to separate a diversity of chemicals in a continuous manner with high purity. However, distillation has an enormous environmental footprint, resulting in the… Design and operation of a distillation tower depends on the feed and desired products. Given a simple, binary component feed, analytical methods such as the McCabe–Thiele method or the Fenske equation can be used. For a multi-component feed, simulation models are used both for design and operation. Moreover, the efficiencies of the vapor–liquid contact devices (referred to as "plates" or "trays") used in distillation towers are typically lower than that of a theoretical 100% efficient equilibrium stage. Hence, a distillation tower needs more trays than the number of theoretical vapor–liquid equilibrium stages. A variety of models have been postulated to estimate tray efficiencies. In modern industrial uses, a packing material is used in the column instead of trays when low pressure drops across the column are required. Other factors that favor packing are: vacuum systems, smaller diameter columns, corrosive systems, systems prone to foaming, systems requiring low liquid holdup, and batch distillation. Conversely, factors that favor plate columns are: presence of solids in feed, high liquid rates, large column diameters, complex columns, columns with wide feed composition variation, columns with a chemical reaction, absorption columns, columns limited by foundation weight tolerance, low liquid rate, large turn-down ratio and those processes subject to process surges. Alcoh…