| In recent years the development of CFB oxy-fuel combustion technology canmake full use of the circulated fluidized bed clean combustion technology and theadvantage of oxy-fuel combustion technology. Steam as an important component inthe boiler flue gas, especially in the wet flue gas circulation mode, the steamconcentration increased, while the presence of steam will change the limestonedesulphurization mechanism and the limestone conversion. In this paper, theexperimental study on the sulphation characteristics of limestone under O2/CO2atmosphere was done, mainly considering the effect of steam on the limestone ofthe calcination and the sulphation. The results showed that the steam has a little effectin the chemical reaction control stage, mainly to promote the diffusion control phase.When limestone calcine completely, the effect of steam is not large. While thelimestone calcination time delay in full, the effect is obvious in promoting from thebeginning. When sulfide and calcine containing steam, calcium conversion rate obtainthe maximum value. The calcination samples from O2/CO2atmosphere comparedwith the air, the specific surface area and pore volume decreased greatly and the steamhas obvious effect that promote the sintering in the air condition and to activate theeffect of pore structure under the condition of oxy-fuel to some degree. Too highcalcination temperature will also promote the calcined samples sintered and differenttypes of limestone has different pore structure characteristics. When limestonecalcination time extended, calcination sample pore structure change worse obviouslyand specific surface area and pore volume decrease. When calcination atmospherecontains steam, extend the calcination time with steam compared with out that the bighole volume increased obviously. Through the establishment of the limestonecalcination and sintering model to simulate the limestone calcination under differentCO2concentration, the model has good agreement with the experimental result. |
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