Heat Transfer Characteristic in Oxy-fuel Circulating Fluidized Bed Boiler

The heat transfer in oxy-fuel circulating fluidized bed boiler(CFBB) was investigated.A model which considers the influence of gases radiation on heat transfer coefficient was set.Take a 440t/h CFBB for example,the heat transfer in furnace was calculated and the results were compared with air-fired CFBB.The model shows the heat transfer coefficient is not be changed greatly in oxy-fuel combustion,because the heat transfer is dominated by the effect of particles,not depend on gases composition.The concept design of oxy-fuel CFBB was done at 30%,50%,and 70% O 2 concentration.It was found the higher concentration of oxygen the more necessary to set an external heat exchanger to keep a normal operation of the furnace.