Robust control of a catalytic fixed bed reactor

Catalytic fixed bed reactors exhibit interesting control problems due to their nonlinear behaviour and their sensitivity to load changes and other disturbances. Because detailed nonlinear models of such reactors are too complex for use in controller design, a linear model description is identified here along with an appropriate structured uncertainty description. The controller is designed based on the μ-paradigm to guarantee robust stability and robust performance. A comparison with an H_∞-optimal controller is also given. For the H_∞-design the structured uncertainties are converted into a single multivariable unstructured uncertainty. As expected the H_∞-controller can only achieve a much less demanding performance because of the conservatism of the unstructured uncertainty description. Experimental results involving a real reactor are given.