Enhancement of indirect sulphation of limestone by steam addition.
The effect of water (H₂O(g)) on in situ SO₂ capture using limestone injection under (FBC) conditions was studied using a thermobalance and tube furnace. The indirect sulphation reaction was found to be greatly enhanced in the presence of H₂O(g). Stoichiometric conversion of samples occurred when sulphated with a synthetic flue gas containing 15% H₂O(g) in under 10 h, which is equivalent to a 45% increase in conversion as compared to sulphation without H₂O(g). Using gas pycnometry and nitrogen adsorption methods, it was shown that limestone samples sulphated in the presence of H₂O(g) undergo increased particle densification without any significant changes to pore area or volume. The microstructural changes and observed increase in conversion were attributed to enhanced solid-state diffusion in CaO/CaSO₄ in the presence of H₂O(g). Given steam has been shown to have such a strong influence on sulphation, whereas it had been previously regarded as inert, may prompt a revisiting of the classically accepted sulphation models and phenomena. These findings also suggest that steam injection may be used to enhance sulfur capture performance in fluidized beds firing low-moisture fuels such as petroleum coke.
Department of Chemical and Biological Engineering, University of Ottawa, Ontario, Canada.
Michael C
MC
Stewart
Vasilije
V
Manovic
Edward J
EJ
Anthony
Arturo
A
Macchi
D000393:Air Pollutants / Q000737:chemistry*; D000397:Air Pollution / Q000517:prevention & control*; D002119:Calcium Carbonate / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D011210:Power Plants; D013227:Steam; D013431:Sulfates / Q000737:chemistry*; D013458:Sulfur Dioxide / Q000737:chemistry
D000393:Air Pollutants; D013227:Steam; D013431:Sulfates; D013458:Sulfur Dioxide; D002119:Calcium Carbonate