Experimental Study Of Semi-dry NID For Sintering Flue Gas

The experiments of semi-dry New Integrated Desulfurization from sintering flue gas wasinvestigated in this paper. At the same time, the influence of the operation parameters ondesulfurization efficiency was also considered. The results was the following:During the semi-pilot experiments, the desulfurizer was prepared and selected. The optimalprepared parameters: the temperature of water was about25℃, the stirring speed was300rpm,the stirring time was5min. The results showed that desulfurizer contained metal oxides such asZnO、 Fe2O3, which was benefit to desulfurization. In case of the low initial SO2concentration(1400mg/Nm3), the optimal parameters were1.8H2O/Ca,1.4Ca/S,110℃reactiontemperature,150circulating ratio and1s residence time. The outlet concentration was below100mg/Nm3, and the desulfurization efficiency reached98%. As for the high initial SO2concentration(2800mg/Nm3), the optimum operation parameters were1.8H2O/Ca,1.6Ca/S,120℃reaction temperature,150circulating ratio and1s residence time. The outletconcentration was about200mg/Nm3, and the desulfurization efficiency was91%. In addition,the semi-pilot experimental results indicated that lower initial SO2concentration was moreeffective in removing SO2. Meanwhile, there was a difference in the optimum operationparameters between the high SO2initial concentration (2800mg/Nm3) and low SO2concentration(1400mg/Nm3).In the field experiments, a high inlet concentration resulted in a low desulfurizationefficiency. While the temperature of inlet flue gas promoted the desulfurization efficiency. Theresults indicated the concentration of outlet flue gas initially decreas ed and followed increasedwith the increase of H2O/Ca, the highest value occurred at a H2O/CaO of1.8, the recommendedrange was1.8~2.0. In low inlet concentration conditions, the desulfurization efficiency increasedwith Ca/S when it was below1.6, the recommended range was1.4~1.6. While in the high inletconcentration conditions, the increase of Ca/S has no negative effect on the desulfurizationprocess until it reached1.8, the optimal conditions was1.8~2.0. The influence of the operationparameters was the following: H2O/CaO> Ca/S> inlet temperature. The results of technical andeconomic analysis on the semi-dry NID showed the operation cost was14.28million yuan everyyear, and the costs for removing SO2was2,600yuan per ton.