Effects of flue gas components on the reaction of Ca(OH){sub 2} with SO{sub 2}
- National Taiwan University, Taipei (Taiwan). Dept. of Chemical Engineering
A differential fixed-bed reactor was employed to study the effects of the flue gas components, H{sub 2}O, CO{sub 2}, NOx, and O{sub 2}, on the reaction between Ca(OH){sub 2} and SO{sub 2} under conditions similar to those in the bag filters of a spray-drying flue gas desulfurization (FGD) system. The presence of CO{sub 2} with SO{sub 2} in the gas phase enhanced the sulfation of Ca(OH){sub 2} only when NOx was also present. When either NOx (mainly NO) or O{sub 2} was present with SO{sub 2}, the enhancement effect was slight, but became great when both NOx and O{sub 2} were present, and was even greater when CO{sub 2} was also present. The great enhancement effect exerted by the presence of NOx/O{sub 2} resulted from the rise in the NO{sub 2} concentration, which enhanced the oxidation of HSO{sub 3}- and SO{sub 3}{sup 2-} to SO{sub 4}{sup 2-} in the water layer adsorbed on Ca(OH){sub 2} surface and the formation of deliquescent salts of calcium nitrite and nitrate. The enhancement effect due to the presence of NOx/O{sub 2} was more pronounced when the relative humidity was above that at which the salts deliquesced; the extent of sulfation was more than twice that obtained when SO{sub 2} alone was present. The presence of H{sub 2}O, CO{sub 2}, NOx, and O{sub 2} in the flue gas is beneficial to the SO{sub 2} capture in the low-temperature dry and semidry FGD processes. The presence of NOx/O{sub 2} also enhanced CO{sub 2} removal when SO{sub 2} was absent.
- OSTI ID:
- 20847713
- Journal Information:
- Industrial and Engineering Chemistry Research, Vol. 45, Issue 26; ISSN 0888-5885
- Country of Publication:
- United States
- Language:
- English
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