A Study on Heat Transfer Model in Sparse Zone of Oxy-Fuel Fired CFB

A model has been developed to calculate the coefficient heat transfer in sparse zone of oxy-fuel fired circulating fluidized bed boiler (CFBB). The model shows that the convective heat transfer coefficient is enhanced with increase in CO₂ density, bed temperature, and decrease in particle diameter; and, the radiative heat transfer coefficient is enhanced with increase in bed temperature and CO₂ density. It was be found that temperature has important influence on both radiative and convective heat transfer. The CO₂ density is very important in enhancing the radiative heat transfer. For example, the total heat transfer could be 264.0 w/(m²·k) when the CO₂ density is 80% when flue gas at 1273 K.