Circulating fluidized bed combustion experiments of three typical coals (lignite

bituminite and anthracite) were performed in a bench-scale combustor. Mercury migration between flue gas and fly ash in three typical coals was studied. The mercury migration for different coals were similar under different conditions of furnace temperature

wind speed

and coal grain size. With decreasing temperature in the furnace dense-phase zone and increasing empty section wind speed

the conversion of fly cash particles mercury (Hg(p)) increased

and the conversion of flue gas gaseous elemental mercury Hg0(g) into Hg2+(g) and Hg(p) also increased. As coal feed increased

Flue gas gaseous mercury HgT(g) content and elemental mercury content decreased

however fly ash particles mercury Hg(p) levels increased

meanwhile the transformation of Hg0(g) was affected. An appropriate coal grain size could promote the conversion of Hg0(g) and the migration of flue gas HgT(g) to fly ash. HgT(g)

Hg(p) and Hg0(g) contents of lignite

bituminite and anthracite had similar changing trend

but differed widely under different combustion conditions. Meanwhile

the percentages of flue gas elemental mercury Hg0(g) in total flue gas mercury HgT(g) were also different

and that of anthracite was much higher than those of lignite and bituminite under various combustion conditions.