Simulation of Combustion Characteristics of Circulating Fluidized Bed Boiler

Thehigh temperatureflow fields ofsolid particles, gasesand heat in a circulating fluidized bed (CFB) boiler, wereempirically approximated, mathematically modeled, theoretically analyzed, and numerically simulated in finite element method with software Fluent for design optimization. The influence of the secondary air-inlet position on the combustion behavior, including the temperature profile, velocity distribution andtrajectories of particles, was investigated. The axial distribution of solid volume fraction of coal, profiles of air-velocity and temperature were simulated; and a localized turbulence appears inthe J-shaped solid-feed recycle device. In the furnace, the radial temperature profile decreases with the increasing radius. The optimized secondary air-inlet position lowers the temperature by 50℃ in the separator, vertical tube and solid-feed recycle device, significantly reducing the heat-loss of the furnace off-gases. We suggest that the simulated results be of some technological interest in energy saving of CFB boiler.