Oxidation Reaction of Calcium Sulfide in an Advanced PFBC Condition (II)

Sulfation Reaction and Grain Model Application

Abstract

The effects of particle size, O₂ concentration, temperature, and sorbent type on sulfation of calcium sulfide were investigated at temperatures of 650 to 850°C Calcium sulfide particle is oxidized to CaSO₄ through reaction: CaS + 2O₂↑CaSO₄ when reaction temperature is below 850°C. CaS particle with a diameter below 0.005 mm was found to achieve complete conversion to CaSO4. However, CaS particle with a diameter above 0.02 mm wasn't be completely converted to CaSO4 due to the pore blockage of sulfate product layer. A kinetic study of the sulfation reaction (CaS + 2O₂ ↑CaSO₄) has shown its activation energy to be 57.2 kJ/mol. A grain model has been developed to analyze the oxidation reaction within a CaS particle. The effects of temperature, O₂ concentration, particle size and type of limestone on the reaction process were discussed.