Potassium chloride, KCl, formed from biomass combustion may lead to ash deposition and corrosion problems in
boilers. Sulfates are effective additives for converting KCl to the less harmful K2SO4 and HCl. In the present study, the rate
constants for decomposition of ammonium sulfate and aluminum sulfate were obtained from experiments in a fast heating rate
thermogravimetric analyzer. The yields of SO2 and SO3 from the decomposition were investigated in a tube reactor at 600−900
°C, revealing a constant distribution of about 15% SO2 and 85% SO3 from aluminum sulfate decomposition and a temperaturedependent
distribution of SO2 and SO3 from ammonium sulfate decomposition. On the basis of these data as well as earlier
results, a detailed chemical kinetic model for sulfation of KCl by a range of sulfate additives was established. Modeling results
were compared to biomass combustion experiments in a bubbling fluidized-bed reactor using ammonium sulfate, aluminum
sulfate, and ferric sulfate as additives. The simulation results for ammonium sulfate and ferric sulfate addition compared favorably
to the experiments. The predictions for aluminum sulfate addition were only partly in agreement with the experimental results,
implying a need for further investigations. Predictions for the effectiveness of the sulfur-based additives indicate that ferric sulfate
and ammonium sulfate have similar effectiveness at temperatures ranging from approximately 850 to 900 °C, whereas ferric
sulfate is more efficient at higher temperatures and ammonium sulfate is more effective at lower temperatures.
Potassium chloride, KCl, formed from biomass combustion may lead to ash deposition and corrosion problems inboilers. Sulfates are effective additives for converting KCl to the less harmful K2SO4 and HCl. In the present study, the rateconstants for decomposition of ammonium sulfate and aluminum sulfate were obtained from experiments in a fast heating ratethermogravimetric analyzer. The yields of SO2 and SO3 from the decomposition were investigated in a tube reactor at 600−900°C, revealing a constant distribution of about 15% SO2 and 85% SO3 from aluminum sulfate decomposition and a temperaturedependentdistribution of SO2 and SO3 from ammonium sulfate decomposition. On the basis of these data as well as earlierresults, a detailed chemical kinetic model for sulfation of KCl by a range of sulfate additives was established. Modeling resultswere compared to biomass combustion experiments in a bubbling fluidized-bed reactor using ammonium sulfate, aluminumsulfate, and ferric sulfate as additives. The simulation results for ammonium sulfate and ferric sulfate addition compared favorablyto the experiments. The predictions for aluminum sulfate addition were only partly in agreement with the experimental results,implying a need for further investigations. Predictions for the effectiveness of the sulfur-based additives indicate that ferric sulfateand ammonium sulfate have similar effectiveness at temperatures ranging from approximately 850 to 900 °C, whereas ferricsulfate is more efficient at higher temperatures and ammonium sulfate is more effective at lower temperatures.
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