Experimental and bifurcation analysis of a hybrid CSTR plant

The classical continuous stirred tank reactor (CSTR) with an exothermic chemical reaction is known for its complex nonlinear behaviour. Therefore, it is often used as a benchmark plant for testing control algorithms. Since experimenting with a real chemical process can be dangerous (thermal runaway), computer simulations can be used in the controller design. On the other hand, simulation results are obtained for mathematical models that often include many simplifying assumptions. Hence, the goal of this study was to design a hybrid CSTR (hCSTR) plant with real reactor vessel and jacket, but simulated chemical reaction. Based on bifurcation analysis and laboratory experiments, it is shown that the hCSTR plant exhibits the same qualitative behaviour (multiplicity of steady states and limit cycles) as the classical CSTR system. The analysis is performed assuming hard-saturation constraints on the reaction heat, since the heating power in the real hybrid plant is also constrained. Finally, a proportional-integral (PI) controller for stabilization of temperature in the vessel is designed and tested by using the hCSTR plant.