MODELING OF SULFIDED ZINC TITANATE REGENERATION IN A FLUIDIZED-BED REACTOR .2. SCALE-UP OF THE SOLID CONVERSION MODEL

Hot gas desulfurization with regenerable metal oxide sorbents is an es sential part of the simplified integrated gasification combined cycle process which is currently being demonstrated at commercial scale. As part of a sulfur removal process development, Carbona Corporation is d eveloping fluidized-bed reactor models for scale-up. In the first part of this work, the parameters for an uniform conversion model were det ermined to describe the conversion rate of ZnS regeneration with oxyge n. A method using the uniform conversion model for fluidized-bed appli cation is presented in this paper. The apparent activation energy for the global reaction rate constant obtained from pilot-scale fluidized- bed tests is 200-210 kJ/mol. When using these reaction rate constants as inputs of a sensitivity analysis for a large-scale reactor model, i n comparison with the rate constants reported earlier, some difference s can be observed. The significance of the differences are discussed. It is stated that any zinc sulfate formed in fluidized-bed regeneratio n at temperatures 500-600 degrees C will decompose, forming SO2, at th e actual regeneration temperatures of the bed (725-800 degrees C) due to neglible O-2 partial pressure.