Asymptotic observers for fixed bed reactors

The online estimation of reactant and product concentrations in fixed bed reactors is considered. It is shown how to extend to tubular reactors the asymptotic observer developed for stirred tank reactors. The proposed observer can be viewed as an alternative to classical observers (extended Kalman filter and extended Luenberger observer). Two of its main features are that it is independent of the knowledge of the kinetics and that its implementation does not require the fulfillment of any observability conditions. The practical implementation leads to the reduction of partial differential equations to a finite number of ordinary differential equations. With this approximation, this asymptotic observer is capable of reconstructing the state of the system from the measurement of a number of state variables (temperature and component concentrations) equal to the number of independent reactions (a reversible reaction being considered as one reaction) at a finite number of positions along the reactor. It is shown that the stability and convergence properties of the proposed method depend on the hydrodynamics and not on the kinetics.Anglai