Small-scale pasteurization plants: modeling and real-time control
Document typeMaster thesis
Rights accessOpen Access
The pasteurization process is one of the most common treatments in the food industries in order to eliminate harmful pathogenic and spoilage microorganism. The process consists in maintaining a high temperature stablished during a short period of time (HTST). Most of the pasteurization plants are controlled by tradicional PID (ProportionasIntegral-Derivative). Much effort has been made to develop advanced controllers. However, an accurate model that describes the system is required. The main of the present project is to develop a dynamical model for a pasteurization plant for a real-time control. Experimental plant consists in a small-scale pasteurization plant PCT23 MKII completely monitorized owned by the enterprise Armfield. The first task refers to modelling the different elements of the plant. Each one is modelled using the physical principles resulting a nonlinear model. Different parameters of the proposed model are later estimated by experimental data. Finally, the complete model is validated by new experimental data. Linear parameter-varying (LPV) model represents a class of non-linear systems that can be controlled using powerful linear-like techniques. As a nonlinear model is proposed to describe the real system, the second task refers to develop LPV) model. Results shows that the proposed models fit the experimental data with an error lower than a 3 %. Advanced controllers could be designed using these models. As a first approach a PID controller has been designed. The control objective is leading the controlled variables (temperatures) in order to reach the set point rejecting the disturbances.