A novel method for detecting and computing univolatility curves in ternary mixtures

Abstract

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao. b s t r a c tResidue curve maps (RCMs) and univolatility curves are crucial tools for analysis and design of distillation processes. Even in the case of ternary mixtures, the topology of these maps is highly non-trivial. We propose a novel method allowing detection and computation of univolatility curves in homogeneous ternary mixtures independently of the presence of azeotropes, which is particularly important in the case of zeotropic mixtures. The method is based on the analysis of the geometry of the boiling temperature surface constrained by the univolatility condition. The introduced concepts of the generalized univolatility and unidistribution curves in the three dimensional composition -temperature state space lead to a simple and efficient algorithm of computation of the univolatility curves. Two peculiar ternary systems, namely diethylamine -chloroform -methanol and hexane -benzene -hexafluorobenzene are used for illustration. When varying pressure, tangential azeotropy, bi-ternary azeotropy, saddle-node ternary azeotrope, and bi-binary azeotropy are identified. Moreover, rare univolatility curves starting and ending on the same binary side are found. In both examples, a distinctive crossing shape of the univolatility curve appears as a consequence of the existence of a common tangent point between the three dimensional univolatility hypersurface and the boiling temperature surface.

Size-induced axial band structure and directional flow of a ternary-size granular material in a 3-D horizontal rotating drum

“…37 Furthermore, ternary granular mixtures have practical significance too, e.g., the gasification of rice husk can be improved by adding silicon sand and coal; 41 the performance of the ironmaking blast furnace can be improved by charging the fine particles on top of the medium particles to avoid undesired percolation, and large particles to the furnace center to form a strong central gas flow with smooth solid burden discharging; 39 the ternary diethylamine-chloroform-methanol mixture in the separation and distillation industry that gives the unusual univolatility curve. 42 For the rotating drum, ternary-size mixtures received comparatively less attention than binary-size mixtures, although one of the first reports on the axial segregation phenomenon nearly 80 years ago in the rotating drum was based on a ternary-size limestone mixture. 43 By means of DEM, Rapaport 44 numerically studied the axial segregation of a ternary mixture in a rotating drum and found that the axial band formation is such that the medium-size particles tend to be located between the bands of small and large particles.…”

Optimal Design and Effective Control of Triple-Column Extractive Distillation for Separating Ethyl Acetate/Ethanol/Water with Multiazeotrope

“…In this work, the volatility order B AE indicates that B is the first possible distillate product in this section. The feasibility region A BE of this class is located in the lower part of the ternary diagram. − Similar analysis can be carried out for the volatility orders C AE and C BE. Only when the entrainer flow rate is larger than this minimum value, the separation is feasible and the component A could be obtained at the distillate stream by a direct column configuration.…”

Double Ternary Azeotrope in the Benzene + Perfluorobenzene + Water System at 101 kPa

“…Such systems occur in nature much more often than systems containing two internal azeotropes (biazeotropic systems). The existence of two internal azeotropes in some binary mixtures was confirmed experimentally − and in ternary mixtures just by mathematical modeling. − Biazeotropic binary system benzene (B) + perfluorobenzene (PFB) is the most studied one. This mixture is characterized by the complex nature of the phase behavior: the vapor–liquid equilibrium diagram contains two azeotropes (with minimum and maximum boiling points at constant pressure ,,− ), the liquid–solid equilibrium diagram contains two eutectic points, and a solid-phase intermolecular complex is formed in mixture B + PFB at room temperature. , No less interesting is the behavior of this system in the presence of water (W).…”