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NO{sub 2} absorption in limestone slurry for flue gas desulfurization

Technical Report ·
OSTI ID:121455
;  [1]
  1. Univ. of Texas, Austin, TX (United States)
We have measured rates of NO{sub 2} absorption and sulfate oxidation in a highly characterized stirred cell contactor, at pH 4.5 to 6.0, 25 to 55{degrees}C, and solution compositions typical of limestone slurry scrubbing. The rate constants of the reactions between NO{sub 2} and sulfate (SO{sub 3}=), bisulfite (HSO{sub 3}-) and water at 55{degrees}C were 11.2x10{sup 5} M{sup -1}s{sup -1}, 2.8x10{sup 4} M{sup -1}s{sup -1}, and 1.6xl0{sup 7} M{sup -1}s{sup -1}, respectively. NO{sub 2} absorption catalyzes sulfate oxidation in the presence of oxygen, which may lead to depletion of sulfate at the interface and reduce the rate of NO{sub 2} absorption. For every mole of NO{sub 2} absorbed, 4 to 160 moles of sulfite may be oxidized. Higher pH favors NO{sub 2} absorption, while additives such as Mg{sup 2+}, Ca{sup 2+}, and Cl{sup -} inhibit NO{sub 2} removal. The presence of buffer or oxidation inhibitor enhances the rate of NO{sub 2} absorption.
Research Organization:
Electric Power Research Inst., Palo Alto, CA (United States)
OSTI ID:
121455
Report Number(s):
EPRI-TR--105258-Vol.3; CONF-950332--Vol.3
Country of Publication:
United States
Language:
English