Studies On The Dynamic Model, Simulation And Control Of Distillation Column

A set of dynamic model and its application for simulation, advanced control of distillation column were studied. The main points and results of this thesis are as follows.1.The equilibrium stage dynamic model of distillation column for computer simulation is developed. The distillation is divided into general column stage region, reflux region, column top and condenser region, pump around region, column bottom region and reboiler region. Each region is modeled separately ana consist to a whole model. The computing time is shorted by using step_variable integral algorithms and by simplifying the model equations. Simulation results reveal that, compared with actual data trend, this model can predict the dynamics and steady trends.As a result,this model can be applied to the analysis and design of control system.2. A simplified model of pump around region is obtainned by frequency domain analysis method. In this method, heat exchanger and transport line, which are discriped with partial differential equation, can be simplified to ordinary differential equation with time delay.This simplified form still retain equipment and fluid characteristics, and can be conveniently used in control and calculation. Pump around systems is one of the component of the distillation column dynamic model.3. The controllability and observability of the distillation column are discussed. Controllability and observability play an important roll in the design, operation and control of distillation process. A convenient systemstructural analysis method which provided a necessary condition of controllability and observabillity is proposed in this thesis. The analysis results are essential to implementation of advanced control of distillation process.4. The advanced control of distillation column is developed. By analysing manipulated variables feature, a multivariable coordination and predictive control strategy is proposed. A state feedback predictive control algorithm and simplified model for control are derived.With PID control system, the advanced control system can minimize energy consumption by bringing manipulated variables to their ideal resting values while keep controlled variables at their setpoints or within zone limits.5. A process simulation system based on dynamic model and personal computers is developed. The simulation software based on DOS is simple and suitable for distillation process change. A new simulation environment based on industry configuration software is proposed. This environment can imitate distillation process vividly. The dynamic model of distillation column is installed in the system, which provided an environment for process control. This simulator can also be used as a process analyzer and a training simulator.