STATE PROFILE ESTIMATION OF AN AUTOTHERMAL PERIODIC FIXED-BED REACTOR

In this paper, the state profile estimation of a novel autothermal fix ed-bed reactor (called circulation loop reactor, CLR), which can be op erated as an autonomous periodic system, is studied. Since in autother mal operation the reactor shows sustained large oscillations, its dyna mics have to be modelled as a strongly nonlinear distributed parameter system. The generally used lumping techniques (e.g. the orthogonal co llocation method) for designing the state estimator of fixed-bed react ors are not applicable in this case. An approach for estimating the st ate profiles of the CLR based on a nonlinear distributed parameter obs erver is presented. To decrease the computational effort of the observ er in real-time applications, the reduction of the detailed model of t he CLR is investigated. In order to achieve asymptotic stability and f ast convergence of the observer, the observability of the CLR is analy sed, and use of features of the sustained oscillatory system and physi cal insight are made. A method based on exponential weighting function s is proposed to approximate the observation error profile. The temper ature and concentration profiles are estimated from a small number of temperature measurements. The obtained observer was successfully teste d with the dynamic simulator DIVA in the cases of errors in the initia l condition and the model parameters, random noisy measurements, and u nknown disturbances, also including the different choice of sensor loc ations, and different observer parameters. It shows excellent dynamic tracking of the reactor profiles, strong robustness, and easy tuning. It forms a basis for developing appropriate control strategies of the CLR. (C) 1997 Elsevier Science Ltd.