Some aspects of CFD modelling for circulating fluidized bed converters

Övrigt konferensbidrag, 2006

Important features for numerical investigation of the fluid dynamics of industrially-sized fluidized-bed converters are investigated. Emphasis is put on the significance of inlet boundary conditions for simulations of the units. Simulations of a stationary fluidized bed are carried out as a step towards computations of a circulating fluidized-bed reactor. The simulations are based on an Eulerian approach, using the kinetic theory of granular flow. The results are compared with time-averaged measurements (mean concentration of particles) and local instantaneous pressure measurements. The simulations show satisfactory agreement with experiments, which demonstrates that the assumption of a uniform inlet gas flow over the air distributor is not appropriate in numerical studies of beds operated under the conditions of industrial units. It is concluded that fluctuations in pressure and flow in the air-supply system have to be taken into account when formulating the inlet conditions for the calculations.