The interaction of limestone calcination and sulfation in simultaneous calcination/sulfation under circulating fluidized bed furnace conditions was studied by constant-temperature thermogravimetric setup. The sulfation reaction took place simultaneously with calcination and CaSO4 was formed in the particles when SO2 was present. Compared to pure calcination condition

the mass loss rate of limestone calcined in the presence of SO2 was lower but the final mass was higher. Limestone calcination was slowed down by SO2 presence and the calcination rate decreased with increase of SO2 concentration within the range of 0-0.3%. A probable mechanism was proposed that CaSO4 formation by SO2 sulfation with CaO of limestone particles upon calcination may fill or plug pores in CaO layer

impede CO2 transfer

and hinder calcination reaction. The mechanism of SO2 inhibition on limestone calcination was supported by product pore structure analysis and calculation that some pores were plugged and effective CO2 diffusion coefficient in pores was reduced. However

the calcination rate of limestone was increased with particle size decreased from 0.4-0.45 mm to 0.2-0.25 mm

no matter whether there was SO2 or not. Temperature also largely affected calcination

SO2 impeding effect was less pronounced at 880℃ than at 850℃

which was probably due to reduced pore plug of CaSO4 at 880℃.