| Phase equilibrium theory is the basis for separation technology, equipment designing and accurate process simulation. Equilibrium data implies the limitation of separation. For the system relative volatility is close to 1, special distillation technology is usually adopted in industry, such as extractive distillation and azeotropic distillation. The basic principle is to add solvent as a third component in order to increase the relative volatility. Therefore, equilibrium data of multicomponents system with solvent has great importance for those hard separation systems.In view of the above mentioned facts, systems including benzene-thiophene and acetic acid-water which are difficult to separate by conventional distillation are considered in this work. Vapor-liquid phase equilibrium data of multi-components system added with solvent were measured, in order to provide accurate and reliable thermodynamic basic data for the process of separation designing, reconstruction, innovation and simulation.Isobaric vapor-liquid equilibrium(VLE) data for two ternary system benzene-thiophene- dimethyl sulfoxide(DMSO), acetic acid- sec-butyl acetate(SBA)- water, and three constituent binary systems containing benzene- thiophene, benzene-DMSO, acetic acid- SBA were measured at 101.33 kPa, respectively. The apparatus of the experiments is an all-glassed double recirculating equilibrium still. The experimental data of binary systems were verified thermodynamically consistent when tested by the Herington method. Both the NRTL and UNIQUAC models were used for correlating and estimating the measured binary data. The nonideality of vapor phase for system include acetic acid was corrected by the chemical theory model and the Hayden-O’Connell(HOC) model. UNIQUAC model parameters obtained from the experimental and literature binary data were used to predict the ternary VLE data. The ternary predicted values are consistent well with the experimental values. The average absolute deviation of the predicted is less than 3%, which shows a satisfactory prediction for the two ternary systems.In addition, an extraction-azeotropic distillation integrated method is put forward for acetic acid dehydration. In extraction unit, the feasibility of this separation process and the reliability of parameters in simulating are proved by the intermittent extraction experiments with SBA as the solvent. And then, an integrated separation flow sheet is established, executed and optimized by the steady state simulation software Aspen Plus. Finally, Pinch analysis for heat exchangers network of this process is implemented with the lowest energy consumption as a target. In the same way, the energy consumption of this separation process were studied with the other two solvents, n-propyl acetate(NPA) and iso-butyl acetate(IBA), considered in determining the suitable solvent for this system. |
