CHEN Liang, ZHAO Fan, YAN Guangjing, et al. Synergetic effect of H2O and SO2 on calcination kinetics of limestone during simultaneous calcination/sulfation reaction in CFB boilers[J]. CIESC Journal, 2018, (9): 3859-3868. DOI: 10.11949/j.issn.0438-1157.20180450.
DOI:
CHEN Liang, ZHAO Fan, YAN Guangjing, et al. Synergetic effect of H2O and SO2 on calcination kinetics of limestone during simultaneous calcination/sulfation reaction in CFB boilers[J]. CIESC Journal, 2018, (9): 3859-3868. DOI: 10.11949/j.issn.0438-1157.20180450.DOI:
Synergetic effect of H2O and SO2 on calcination kinetics of limestone during simultaneous calcination/sulfation reaction in CFB boilers
The simultaneous calcination/sulfation reaction is the real reaction process of limestone in circulating fluidized bed (CFB) boiler. To obtain the true calcination process of limestone in CFB
the combined effect of H2O and SO2 on the calcination kinetics and pore structure of limestone during simultaneous calcination/sulfation reaction under CFB conditions was studied in a constant-temperature reactor. H2O (0-15%) can accelerate the calcination of CaCO3. The SO2 in flue gas decreased the calcination rate of limestone particles. This phenomenon was explained by a mechanism based on the measurement of pore structure
namely that SO2 reacted with CaO layer
and the formed CaSO4 would fill or block the pore in CaO layer
decrease the pore volume
increase the diffusion resistance of CO2
and consequently impede the calcination reaction. H2O and SO2 can work synergistically on changing the calcination rate
and an increase of the calcination rate was found under 15% H2O and 0.3% SO2 compared to that without either. This may be because intrinsic reaction played a major role in the rate controlling step of calcination
and H2O accelerated the intrinsic calcination directly. The effect of other factors like temperature and particle size on the calcination rate in the presence of H2O and SO2 were also tested. H2O also accelerated the sintering of CaO significantly
and along with SO2
the pore volume and surface area of CaO decreased further.