2392
Ind. Eng. Chem. Res. 2002, 41, 2392-2398
Reaction between Hydrogen Sulfide and Limestone Calcines M. Hartman,* K. Svoboda, O. Trnka, and Ji. C ˇ erma´ k Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, Rozvojova´ 135, 165 02 Prague 6, Suchdol, Czech Republic
The sulfidation rates of different limestone calcines were measured as weight gain in a differential, fixed-bed flow-through reactor at ambient pressure and high temperatures of up to 800 °C. The increase in volume of the solid phase in the course of the reaction was explored by experiment and described by means of a simple structural model. The reacted solids remain fairly porous (∼20%) even when they are practically converted into CaS. On petrographic examination, eight specimens of commercially exploited limestones were tested to determine their capacity to react with H2S. The calcines prepared from very fine-grained carbonate rocks were found as the most efficient sorbents. Having amassed time-resolved conversion data on CaO sulfidation, we developed a simple correlation. It allows the estimation of the reaction rate as a function of temperature, concentration of hydrogen sulfide in the gas phase, and conversion of the solids. The proposed kinetic equation can readily be employed in modeling and simulation of desulfurization processes. Introduction The gasification of coal is a promising process for coal utilization in which the generated fuel (coal) gas can subsequently be employed to produce energy by combustion or in fuel cells or to synthesize other fuel. In the reducing atmosphere of a gasifier, the sulfur contained in coal is converted predominantly into H2S and, in a lesser extent, to COS.1,2 Because of their corrosive nature and negative impact on the environment, hydrogen sulfide and carbonyl sulfide must be removed from the raw coal gas before it is further processed. Desulfurization of coal gas at high temperatures (>500 °C) with the use of solid sorbents (e.g., oxides of iron, zinc, vanadium, and manganese or calcareous materials) exhibits several technical and economical advantages over low-temperature cleaning technologies (
