Analytic reduced-order dynamic models for large equilibrium staged cascades



A model reduction technique based upon modal analysis is presented for modeling the dynamics of general, large equilibrium staged cascades encountered in chemical processes. The analysis is general enough to encompass quite complex cascades involving multiple fee and/or product streams with nonideal thermodynamic behavior. The low-order models proposed have a number of desirable features: the state variables have physical significance and model parameters are clearly related to the fundamental process parameters which are easily obtainable from steady-state plant data. Quantitatively it is shown that the low-order models proposed are in excellent agreement with the complete (high-order) dynamic models on a range of problems some of which involve complex, nonideal cascades.