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 1273K.