Coupling of a radiative heat transfer model and a three-dimensional combustion model for a circulating fluidized bed furnace

A 3D semi-empirical model for reactive two-phase flow in a circulating fluidized bed furnace (CFB3D) is modified by implementing the radiative zone method to solve the radiation heat transfer. The radiative properties of the gas and particle phase have been calculated using detailed information of gas and particle distribution obtained from the CFB3D model. A recently published WSGGM for oxygen-fired combustion has been used to calculate the absorption coefficient of gaseous combustion products. The results of implementing the radiative zonal approach have been compared with those obtained using empirical radiative correlations. The temperature field obtained by using the radiative zone method is more uniform than the one obtained by empirical correlation, and the total heat flux to the wall is slightly higher. The long distance effect of radiation has been found more important in the upper furnace where the gas is the dominant phase. Detailed discussion concerning the obtained results is presented.