Industrial & Engineering Chemistry Research, Vol.52, No.19, 6470-6479, 2013
Nonlinear Model Predictive Control Based on Wave Model of High-Purity Internal Thermally Coupled Distillation Columns
Although the internal thermally coupled distillation column (ITCDIC) is much more energy-efficient than the conventional distillation column, the complex dynamics stemming from thermal coupling between the rectifying column and the stripping column have restrained the achievement of control strategies and application in chemical industry. To reduce the difficulties, a novel nonlinear wave model of ITCDIC process is proposed based on the wave theory in the separation processes to simplify the mechanism model of ITCDIC. A nonlinear model predictive control based on the proposed wave model (NWMPC) of the ITCDIC process is further established to handle the multivariable interactions and improve the control performance. A dynamic optimization scheme characterized by an improved control parametrization method is introduced to solve the problem generated by the NAA/MPC model. An IMC controller is also explored as a comparison research. In the example of a benzene-toluene system, NWMPC presents great advantage over IMC in the servo and regulatory control.