What is the function of the primary air of a circulating fluidized bed boiler?

　　(1) Form enough air cushion capacity to lift the material layer, ensure the rapid mass transfer of the hot particles of the material layer and the new fuel particles, promote the mixing of cold and hot particles, uniform the bed temperature, and strengthen the heat transfer in the lower part.

　　(2) Supplement enough oxygen in the early stage of ignition and the early stage of the combustion process to produce a good initial stage. Stabilize the combustion state of the ignition and reduction zone, and ensure the boiling combustion fraction and burnout rate of the coarse particle layer.

　　(3) Through the adjustment of the primary air, good control of the bed temperature is realized, and the combustion requirements of circulating fluidization and the bed boiler material bed temperature are within the range of 850~950℃.

　　(4) Under the action of uniform air distribution by the air distribution plate, uniform fluidization of the material layer is realized, and local fluidization abnormalities such as partial bed, throttling and channeling are reduced.

　　(5) Produce a strong fluidized combustion process, promote the thermal rupture of the coarse particles of the material layer, provide a basic group of fine particles for the dense phase zone and the area above, and form the transfer of coarse particles to fine particles.