particles formed by the evaporation and nucleation of metals, only
with a limited amounts because of the low CFB temperature (850–
900 C) in contrast to PC combustion. As shown in Fig. 3 (c and d), it
is obvious to understand that the supermicron fly ash particles are
not spherical; since they are large agglomerates consisting of
primary particles (both nucleated fine particles and fragmented/
attrited particles from bed materials). This kind of particles is
irregular, and some are even porous [35].