A hybrid simulation of a 600 MW supercritical circulating fluidized bed boiler system

Abstract

A hybrid dynamic model for a 600 MW supercritical circulating fluidized bed (CFB) boiler is presented. The combustion system includes combustion chamber, cyclone separator, standpipe, and ash cooler. The steam-water system mainly contains water wall, external heat exchanger, superheater, reheater, and economizer. The ‘core-annulus cell model’ is employed to simulate complex physical and chemical processes in the boiler. A series of classical empirical models have been chosen to model main physical and chemical processes. The water-steam system is modelled by means of modular modelling method, a new user-defined model for external heat exchanger is established and validated. The combustion system is coupled with the water-steam system via heat exchange in water wall tubes. The static state calculation is taken to compare with the design values indicating the model has reached a rather high precision. Dynamic simulations under three typical transient conditions are conducted which are 5% fuel decrease, 5% secondary air decrease and 5% supply water decrease, respectively. The results demonstrate that the hybrid model is capable of performing good characteristics of CFB. The modelling method has important theoretical and engineering values for researchers, and the hyrbid model can be very helpful to optimize operating and design parameters to get a better performance of large-scale commercial CFB.