Formulation and Spectral Reduction of the Dynamical Model of a Circulating Fluidized Bed Combustor

The distributed dynamic model of a circulating fluidized bed combustor in isothermal operation is developed and proposed, consisting of four 1–D evolutionary partial differential equations and relevant boundary and initial conditions. The continuum model is then approximated by a finite–difference method to provide a “reference” solution. Then, proper orthogonal decomposition with Galerkin projection is introduced to derive a reduced order model. The POD modes are then tested in the low-order reconstruction of space profiles of the state variables at different times, during the transient and at steady-state. POD–based models prove to be effective, being able to reproduce steady–state with four basis functions. Quantitative accuracy even during the early transient stage is achieved with as little as 24 modes.