Modelling of hybrid CSTR plant: Heat transfer considerations

The continuously stirred tank reactor (CSTR) may exhibit various nonlinear effects, for example, multi-stability or sustained oscillations. This makes the CSTR one of the most difficult industrial units for control and the system instability or thermal runaway indicate that the safety issues must also be taken into account. In comparison to the real reactor, a hybrid system is safe and less expensive alternative for testing new concepts in control. In this paper, we consider a hybrid reactor that consist of a jacketed vessel and LabVIEW based real-time simulator of a chemical reaction. To make the hybrid reactor a highly nonlinear benchmark plant, the system parameters must be carefully selected. Instead of making time consuming experiments, the preliminary simulation tests would be helpful in selection of the process parameters. For this purpose three models of various complexity for the real hybrid reactor are developed. We show that an overall heat transfer coefficient cannot be assumed constant to obtain a good agreement between the simulation results and the measurement data. The paper also presents the influence of the coefficient on the dynamical behavior of the hybrid reactor based on the bifurcation analysis.