Study of a circulating fluidized bed furnace behavior in order to scale it up to 600 MWe

Abstract

The furnace constitutes the main component of a Circulating Fluidized Bed boiler. Because of its size and complexity, it has an important influence upon both the overall boiler cost and its operating flexibility. This paper presents the main results of the investigation of the furnace behavior of the E. Huchet boiler, a 125 MWe reheat unit in operation since 1990. It shows the different measurements: pressure profile, boundary layer thickness and temperature, heat transfer coefficient of the waterwalls (from global heat balance and from fluxmeter measurements). Furthermore, some correlations linking the main hydrodynamic and heat transfer parameters are presented and compared to what has been found on other Circulating Fluidized Bed boilers or small-scale experiments. Finally, a simple one-dimensional numerical model resulting from these measurements and correlations is presented, in order to predict the hydrodynamic behavior and the heat transfer in a large capacity Circulating Fluidized Bed combustor, and to stress what should be measured and studied to ensure the development of a reliable numerical model, and also the development of large capacity Circulating Fluidized Bed boilers.