基于样条插值模型的间歇精馏模拟与预测控制

以Aspen Batch Distillation（ABD）中的间歇精馏仿真系统为过程原型，提出了利用过程的模拟测试数据来建立间歇精馏过程的样条插值简化模型（spline interpolation model, SIM）。结合变回流比下的动态修正函数，构造出了一种简单实用的动态模型。该模型可有效模拟不同组分浓度下回流比发生变化时馏出液浓度和流量的动态变化情况。以该模型作为预测模型，进一步提出了一种变回流比的预测控制（model predictive control, MPC）算法来使馏出液浓度按照期望的设定值变化。控制仿真结果表明该控制方案计算简单，同时具有较好的控制效果。

Simulation and predictive control based on spline interpolation model of batch distillation

Batch distillation is a widely used separation process in chemical engineering.Due to the comparatively small investment and flexibility in production,batch distillation has found various industrial applications in biopharmaceuticals,fine chemicals production and foods processing.To guarantee high product quality,modeling and advanced process control for batch distillation have received significant attention.As an unsteady state dynamic process with strong nonlinearity,however,it is still not easy for engineers to design a control system on the basis of a simple model to guarantee good control performance for batch distillation.In this paper,by using the batch distillation model in Aspen Batch Distillation(ABD)as prototype,the process data of tower residual liquid and distillate compositions under different reflux ratios were obtained firstly.Based on the process data,then,the distillate volume and concentration of the process were formulated by the steady-state spline interpolation models(SIM).To compensate the dynamic error caused by variation of reflux ratios,a simple dynamic model was identified and combined with the steady-state SIM,resulting in a simple dynamic SIM for batch distillation.The comparison of the responses of the proposed SIM and ABD model to the time-varying reflux ratio indicated the applicability and precision of the proposed SIM.By using the SIM as the prediction model,a model predictive control(MPC)algorithm was further proposed for the concentration control of batch distillation.Numerical simulations demonstrated the applicability and robustness of the proposed control scheme for batch distillation with different feed compositions.The proposed control scheme lays a solid foundation for the further studies on online optimization of batch distillation.