| Large amount of CO2emission is one of the most important reasons of global warming.Oxyfuel combustion is the most potential clean coal power generation technology which cancapture mass of CO2. The high concentration of CO2after oxyfuel combustion can be easilygeological storaged or made use of after simple treatment. The study on transformation ofinorganic components under oxyfuel combustion is of great significance to predict the ashdeposition characteristics of boiler.Thermodynamic equilibrium calculation method has been used to investigate thetransformation of components containing Ca, Fe, Mg, K, Al, Si during oxyfuel combustion,and the results was compared with that of air combustion condition. The results indicatedthat Ca, Mg components will gradually carbonation with the temperature decreasing alongwith the flue gas flow. The high concentration of CO2has significant influence on thecarbonation reaction under oxyfuel combustion condition. The Al, Si components willmainly exists in the form of silicate, the addition of SO2will greatly promote the sulfatingreaction.The thermogravimetric experimental result indicated the temperature range of carbonatereaction is400~600℃. The increase of CO2and water vapor concentration are bothfavorable for carbonation, and also for the reaction rate and the highest conversion rate. Theexperiments of horizontal tube furnace were conducted to research the carbonation reactionof actual power plant fly ash and simulated oxyfuel combustion ash. The results confirmedthe promotion of water vapor and CO2concentration on carbonation. The main limiting stepof carbonation is the dynamic process under550℃, while gas diffusion resistance will bethe main react restriction above650℃. There is little effect of ash formed under oxyfuelcombustion on carbonation. Large amounts of Al and Si will reduce carbonation rate. TheXRD analysis results found that CaO in the ash transformed to CaCO3after carbonationreaction. |
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