| The modeling and simulation of chemical engineering has great important on chemical design and unit operation. Building dynamic mathematical model and carrying out system simulation of the distillation column will help to study the varying of distillation at different conditions, and also to develop the advanced control plan for distillation process, furthermore to increase the economic benefits of distillation operation.At first, the methods of calculation for the basic physical properties about distillation process were introduced in this paper, such as vapor enthalpy, liquid enthalpy, activity and vapor-liquid equilibrium. Then, the equilibrium stage dynamic mathematical model of distillation column for computer simulation is developed. The distillation column was divided into six subsidiary units:Reboiler, Column bottom, General column stage, Feed stage, Sidestream stage and Condenser. Each subsidiary unit was modeled separately, and consists to a whole model. Each subsidiary unit's mathematical model was built by MESH equations (Material equation, phase Equilibrium equation, Summation equation, Heat equation). In addition, the startup operation and entrainment phenomenon of distillation process was analyzed, and the mathematical model was built too. Finally, the dynamic mathematical models were simulated by software. The dynamic characteristics of distillation column were investigated through changing the operation parameter such as reboiler steam, feed flow rate and composition and so on.The computing time was greatly shorted by simplifying the model equations according to the mechanism of distillation. The simulation results of perturbation experiments revealed that it can predict the dynamic and steady trends compared with actual data trend. As a result, this model can be applied to the simulation training, the analysis and design of control system. |
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