What are the main factors in the heat transfer of circulating fluidized bed boilers?

　　The heat exchange mechanism of the gas-solid two-phase flow and the heating surface in the combustion chamber of the circulating fluidized bed boiler can be divided into three parts: gas convection, particle convection and the radiation heat transfer of the gas-solid mixture to the heating surface.

　　The heat transfer coefficient of the heating surface is exponentially distributed along the height of the bed. Along with the change in the load of the circulating fluidized bed combustion chamber, the concentration of the material also changes along the bed height. At this time, the heat transfer coefficient of the heated surface along the height of the bed also changes. As the bed temperature increases, the heat transfer increases; the circulation volume increases, and the heat transfer coefficient increases. The fluidization speed has little effect on the heat transfer of the circulating fluidized bed boiler.