Robust global stabilisation of stirred tank reactors by saturated output feedback

This paper is concerned with the robust stabilisation of a wide class of un stable processes operated in continuous stirred tank reactors, For non-isot hermal reactors, the regulated output is the temperature. For isothermal re actors, the regulated output is the single concentration of either an initi al reactant or a final product. In both cases the proposed control law is a dynamic output feedback which can be interpreted as a straightforward modi fication of a standard PI controller. In accordance with the engineering co nstraints, the control action is positive and saturated With this control l aw: it is shown that the output variable may be regulated at a prescribed s et point despite a wide kinetic uncertainty. Furthermore, the controller ac hieves a global stabilisation of the process in its domain of physical exis tence. When the reactor is minimum phase, the closed loop has a single equi librium which is globally asymptotically stable. When the reactor is non-mi nimum phase phase, a global practical output regulation with state boundedn ess is obtained with the same controller.