Fluid phase equilibria

This work shows the experimental data of excess properties at several temperatures and the vapor–liquid equilibria (VLE) obtained for four binary systems of alkyl methanoates (methyl to butyl) with decane, all measured at constant pressure of 101.32kPa. The isobaric VLE data were thermodynamically consistent according to the Fredenslund test and did not present an azeotrope. The experimental data of HmE

A computer algorithm has been developed to determine the cloud and shadow point curves of polydisperse polymer/solvent systems using continuous thermodynamics to represent the polymer. The algorithm is based upon the work of Michelsen [M.L. Michelsen, Fluid Phase Equilibria, 4 (1980), pp. 1–10] and Koak [N. Koak, Polymer Solution Phase Behaviour, PhD Thesis, University of Calgary, Calgary, 1997] where a Newton–Raphson procedure is used to solve the equations defining phase equilibrium for fixed phase segment fractions between 0 and 1. The equations have been developed with the Sanchez–Lacombe equation of state which allows the continuous system to be defined by a set of five equations in five unknowns. Numerical integration is used to determine the values of the indefinite integrals involved. The cloud and shadow curves for a polydisperse polyethylene/n-hexane system were found at 6 bar using both a log-normal distribution and a Schulz–Flory distribution to represent the polyethylene. Compositions of the cloud point curve covered the entire composition range showing the model's behavior in high temperature regions, a hypothetical liquid–vapour critical point and a three-phase point when the log-normal distribution was used. The cloud and shadow point curves of a polyethylene/ethylene system were also found and indicated a high pressure critical point.

Utilization of ferric chelate complex of trans-1,2-cyclohexanediaminetetraacetic acid (CDTA) for the oxidative scrubbing of H2S and CH3SH in Kraft mill streams can be beneficial from the standpoints of iron protection against precipitation and oxygen-mediated regenerative oxidation of the ferrous chelate CDTA. The physical solubility of methyl mercaptan in CDTA–Fe(III) complex cannot be measured directly because of oxidation of the sulfur-bearing

The importance and role of phase equilibria are related to plant design, safety, reliability, operation in chemical and biochemical engineering. For an effective and efficient utilization of large amounts of phase equilibrium data in chemical and biochemical engineering, an intelligent database program for phase equilibrium (PHEQ) data management and application was developed. PHEQ program enables the extraction of data and results so that the time-consuming data management, data processing and analysis are avoided. Furthermore, calculation programs of phase equilibrium based on the most reliable models were implemented. PHEQ Windows allows users to set up problems and to carry out calculations in a simple and rapid manner. It provides access to all PHEQ facilities and can produce output as text files, graphics or Excel worksheets.

In a previous paper [J.N. Jaubert, F. Mutelet, Fluid Phase Equilib. 224 (2004) 285–304], we started to develop a group contribution method aimed at estimating the temperature dependent binary interaction parameters (kij(T)) for the widely used Peng–Robinson equation of state (EOS). In this approach, the kij between two components i and j is a function of temperature (T) and of the pure component critical temperatures (Tci and Tcj), critical pressures (Pci, Pcj) and acentric factors (ωi, ωj). Because our model relies on the Peng–Robinson EOS as published by Peng and Robinson in 1978 and because the addition of a group contribution method to estimate the kij makes it predictive, this model was called PPR78 (predictive 1978, Peng–Robinson EOS). In our previous paper, six groups were defined: CH3, CH2, CH, C, CH4 (methane) and C2H6 (ethane). It was thus possible to estimate the kij for any mixture of saturated hydrocarbons (n-alkanes and branched alkanes), whatever the temperature. In this study, the PPR78 model is extended to systems containing aromatic compounds. To do so, two new groups were added: CHaro and Caro.