In order to study the distribution regularities of fly ash in circulating fluidized bed boilers

the fly ash with different densities at the same particle size was analyzed using X-ray diffraction(XRD)

Maud(whole pattern fitting) and scanning electron microscope(SEM). The distribution regularities of crystalline minerals

amorphous glass and residual carbon in fly ash were investigated. The results show that the mass fraction of the residual carbon in fly ash varied with density. For the fly ash with small densities

unburned carbon would form due to the fly ash's short residence time in the circulating fluidized bed

so the residual carbon content was high. On the other hand

the fly ash with large densities showed a low carbon content because of its long residence time in the circulating fluidized bed(reaching full combustion). The residue carbon content reached the maximum in the fly ash with density ranging from 1.85×103 kg/m3 to 2.15×103 kg/m3. The crystal minerals existed uniformly in the fly ash with different densities. The crystalline minerals

amorphous glass and residual carbon showed dependent distribution patterns. The residual carbon coexisted with Si-Al amorphous minerals in the fly ash. The results provide the basis for the utilization of fly ash in circulating fluidized beds.