Pore structure and particle size effects on limestone capacity for SO2 removal

✍ Scribed by Solon Zarkanitis; Stratis V. Sotirchos

• Publisher: American Institute of Chemical Engineers
• Year: 1989
• Tongue: English
• Weight: 1013 KB
• Volume: 35
• Category: Article
• ISSN: 0001-1541
• DOI: 10.1002/aic.690350513

✦ Synopsis

A detailed investigation of the dependence of the transient behavior of limestone particles reacting with SO2 in the presence of oxygen on the pore structure properties of the calcined solid is presented. Experimental reactivity and pore structure data were obtained for two highpurity limestones that yield calcines of qualitatively similar distribution of pore size but of different capacity for SO, removal. Experiments were carried out over a wide range of particle size and temperature so as to investigate the effects of intraparticle mass transport limitations on the process. The results obtained showed strong dependence of the transient behavior of reacting particles of calcined limestone, and consequently of their sorptive capacity for SO2 removal, on their initial pore size distribution and on the resistance for intraparticle mass transport-which is also determined to a certain extent by the pore size distribution. The experimental results were found to be in agreement with the predictions of a mathematical model for gas-solid reactions with solid product involving porous solids of distributed pore size. The findings point to the conclusion that the evaluation of limestones proposed for use as sorbents for controlling SO, emissions should be based on the size distribution and interconnectedness of the pores of their calcines and not only on their average structural properties (porosity and surface area).