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Thiosulfate as an oxidation inhibitor in flue-gas desulfurization processes: a review of R and D results

Technical Report ·
OSTI ID:6439693

The article describes the pilot-plant testing of sodium thiosulfate (Na/sub 2/S/sub 2/O/sub 3/) as an oxidation inhibitor in flue gas desulfurization by lime and limestone slurry scrubbing with and without MgO and adipic acid additives. The effectiveness of thiosulfate is proportional to the inhibitor product, defined as the product of thiosulfate concentration (M), calcium concentration (M), and the moles of SO/sub 2/ absorbed per hour per liter of hold tank volume. Gypsum saturation was less than 100% and scaling was eliminated when the inhibitor product exceeded 0.3 x 10/sup -6/ M/sup 3/ hr. Thiosulfate was relatively more effective in systems with chlorides and less effective in systems promoted by MgO. An inhibitor product greater than 10/sup -6/ M/sup 3//hr significantly enhanced dewatering of solids from limestone scrubbing. SO/sub 2/ removal and/or limestone utilization were increased in systems that started with less than 10 mM dissolved calcium.

Research Organization:
Environmental Protection Agency, Research Triangle Park, NC (USA). Air and Energy Engineering Research Lab.
OSTI ID:
6439693
Report Number(s):
PB-87-167730/XAB; EPA-600/J-86/277
Country of Publication:
United States
Language:
English