Mathematical Model And Control Scheme Design For Esterification Reaction System Of PET

The research content of this paper is based on the Suzhou polyester production project, during this project, finished the control scheme design of esterification reaction system that including PTA slurry modulation, esterification reaction and esterification vapor separation. The mathematical model of esterification reaction was established based on in-depth research, with reference to previous studies and the Process Flow Diagram which provided by design institute. The reliability of model was proved after simulation.The main variables affecting the esterification reaction are PTA/EG molar ratio, reaction pressure and temperature. On this basis, control scheme of PTA slurry modulation and esterification reaction was designed. The control scheme of PTA slurry modulation is mainly including cascade-ratio control system which designed after in-depth research about the process of slurry modulation, and the temperature correction which can improve control precision was introduced in molar formula during this work. Esterification reactor control scheme that including three control loops was designed based on the research of process features and simulation of esterification reaction mathematical model which can provide the reference to choose the best and the necessary control variables.The esterification steam was separated by distillation tower. The first step is builds simulation model of distillation tower with Aspen Plus, and then does the dynamic simulation of rectification tower with Aspen Dynamics, the simulation results prove the validity of the control scheme. The control scheme of esterification reaction system lay the foundation of prepolycondensation and final polycondensation process, ensure the condensation rate and viscosity keep within the process requirement.