A New Model for the Simulation of Distillation Column

A new computational mass transfer model is proposed for simulating the distillation process by solving the fluctuating mass flux u^＇ic^＇ for the closure of turbulent mass transfer equation in order to obtain the concentration profile and the separation efficiency of distillation column. The feather of the proposed model is to abandon the conventional way of introducing the turbulent mass transfer diffusivity （dispersion coefficient） to the turbulent mass transfer equation. To verify the validity of the proposed model, a commercial scale packed column and a sieve tray column were simulated and compared with published experimental data. The simulated results were satisfactorily confirmed in both concentration distribution and senaration efficiency.

Optimization and control of a reactive distillation process for the synthesis of dimethyl carbonate

Dimethyl carbonate is an environmentally benign and biodegradable chemical.Based on integration of reactive distillation and pressure-swing distillation technologies,a novel process for synthesis of dimethyl carbonate through transesterification with propylene carbonate and methanol has been developed by Huang et al.In this work,the optimization of this process was performed by minimizing the total TAC.The results show that the optimal design flowsheet can save energy consumption by 18.6% with the propylene carbonate conversion of 99.9%.Then,an effective plant-wide control structure for the process was developed.Dynamic simulation results demonstrate that the temperature/flow rate cascade control plus with simple temperature control can keep not only product purity but also the conversion of the reactant at their desired values in the face of the disturbance in reactant feed flow rate and feed composition.

A formulation methodology for multicomponent distillation sequences based on stochastic optimization

Based on stochastic optimization strategy, a formulation methodology is proposed for synthesizing distillation column sequences, allowing more than one middle component as the distributing components between a pair of key components in the non-sharp split. In order to represent and manipulate the distillation configuration structures, a new coding procedure is proposed in the form of one-dimensional array. Theoretically, an array can represent any kind of split(non-sharp and sharp). With the application of a binary sort tree approach, a robust flow sheet encoding and decoding procedure is developed so that the problem formulation and solution becomes tractable. In this paper,the synthesis problem is formulated as a mixed-integer nonlinear programming(MINLP) problem and an improved simulated annealing approach is adopted to solve the optimization problem. Besides, a shortcut method is applied to the evaluation of all required design parameters as well as the total function.

Optimization and Control of Extractive Distillation with Heat Integration for Separating Benzene/Cyclohexane Mixtures

In this work, the extractive distillation with heat integration process is extended to separate the pressure-insensitive benzene-cyclohexane azeotrope by using furfural as the entrainer. The optimal design of extractive distillation process is established to achieve minimum energy requirement using the multi-objective genetic algorithm, and the results show that energy saving for this heat integration process is 15.7%. Finally, the control design is performed to investigate the system's dynamic performance, and three control structures are studied. The pressure-compensated temperature control scheme is proposed based on the first two control structures, and the dynamic responses reveal that the feed disturbances in both flow rate and benzene composition can be mitigated well.