| Simulation and optimization of distillation processes are usually carried out using equilibrium model wherein the vapour phase is assumed to be in equilibrium with the liquid phases leaving the theoretical stages. The equilibrium model is characterized by the Murphree efficiency or Height of Equivalent to a Theoretical Plate (HETP) value since a tray is generally not working like an equilibrium stage. However, these values are not the same in systems with more than two components and cannot be correlated. Especially for complicated multicomponent distillation processes, such as three-phase distillations in this work, the equilibrium model will lead to a significant error in the distillation modelling. Therefore, a novel modelling method is urgent for the increasing demands on the accuracy of distillation model. Nonequilibrium model has been considered and investigated as a novel rigorous simulation method.A topic of great practical and particular industrial interest in recent years has been three-phase azeotropic distillation or heteroazeotropic distillation. This technique is commonly employed to effectively separate azeotropic systems, which are difficult for conventional distillation technique. For heterogeneous azeotropic distillations, three phases, one vapour phase and two liquid phases, can coexist. The existence of the second liquid phase could change the hydrodynamic behaviour and therefore influence the separation efficiency. Meanwhile, the most difficult task for simulation and optimization of heterogeneous distillations is to determine whether the liquid phase is stable in column stages or packing sections, which is also one of the focuses of this dissertation.In this dissertation, a three-phase nonequilibrium model for packed column distillations is developed. The simulation and optimization of three-phase nonequilibrium model are discussed. The main research work and contributions of this dissertation are as follows:1.Three novel equation-solving methods have been developed to solve the phase stability problem of ternary systems with satisfying robustness and rapidness. All three methods belong to the category of nonlinear equation-solving methods. Each of them is confirmed by several ternary systems and can be applied to different phase configurations.2.A rigorous three-phase nonequilibrium distillation model has been developed. The application of that model in three-phase packed column distillations is presented. The performance of this rigorous model is assessed comparing its results with those obtained from the equilibrium model and experimental data. The results show that the nonequilibrium model can give a better prediction of the separation performance than the equilibrium model. Simulated results are verified to be in good agreement with the experimental data.3.Based on the nonequilibrium model, the determination of packing section division for packed column is investigated. It is concluded that the size of packing division can be set the same as NTSM with deviation of less than 1% for two-phase distillation. However, two times the value of packing NTSM is required for three-phase distillation under the same accuracy. More packing section divisions in three-phase distillation are needed compared to two-phase distillation.4.Based on the sensitivity analysis by a step-perturbation test for several most important parameters, the effective interfacial area is found the most sensitive parameter, which affects the separation efficiency in structured packing column significantly. Therefore, a novel optimization method for calculating the effective interfacial area is developed for two and three-phase distillations. The optimization results show that the effective interfacial area hi three-phase distillation is much bigger than the prediction of correlation when the operation condition is above the loading point, while no such phenomena are found when the operation condition is below the loading point.5.The experiments reveal that almost 21% reduction in the...
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