Numerical investigation of particle transport hydrodynamics and coal combustion in an industrial-scale circulating fluidized bed combustor: Effects of coal feeder positions and coal feeding rates

This study investigates particle transport hydrodynamics and coal combustion in an industrial-scale circulating fluidized bed (CFB) combustor using the dense discrete phase model (DDPM). DDPM is an extension of the discrete phase model (DPM); however, unlike the standard formulation of DPM, DDPM considers the solid volume fraction when solving the Navier-Stokes equations for the gas phase. In the DDPM, the kinetic theory of granular flows is used to calculate the particle interaction in the Eulerian frame of reference. This interaction is then mapped to the particles in the Lagrangian frame of reference. In this study, user defined functions (UDFs) were used to extend the ANSYS FLUENT original code. These UDFs were used to reinject particles into to the combustor (cyclones were not modeled), calculate the pressure drop, circulation rate, and combustor mass load control. Various operation indexes such as distributions of gas temperature, solid volume fraction, pressure, and mass fractions of combustion products were displayed, and the selected indexes were compared with operating data obtained from a 340 MWe CFB combustor located in Yeosu, South Korea. The effects of both coal feeder positions and coal feeding rates on operation indexes were investigated.