Removal of SO2 and NOX from Stack Gas by Reaction with Calcium Hydroxide Solids |
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| Authors: | Paul Chu Gary T Rochelle |
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| Institution: | Department of Chemical Engineering , The University of Texas at Austin , Austin , Texas , USA |
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| Abstract: | Previous workers have shown that simultaneous SO2/NOX removal can be obtained in a dry scrubbing system with Ca(OH)2 promoted by an additive such as NaOH, and that fly ash and product recycle improve the reactivity of the solids toward SO2. To test SO2/NOX removal with fly ash and product recycle, bench-scale experiments with a packed bed reactor were performed at bag filter conditions. The most reactive solid for NOX removal was prepared by slurrying Ca(OH)2 with fly ash, CaSO3, and NaOH. The best conditions for NOX removal were the greatest temperature (125°C) and greatest concentrations of SO2 (1500 ppm) and O2 (20 percent). At the best conditions, NOX removed in 1 hour was 3-4 moles per 100 moles Ca(OH)2, compared to 5-10 moles SO2 removed per 100 moles Ca(OH)2. The best SO2 removal was obtained at the highest relative humidities/lowest temperatures (55% RH/ 65°C) with solids prepared by slurrying Ca(OH)2 with fly ash and NaOH. At these conditions, SO2 removed In 1 hour was 60-80 moles per 100 moles Ca(OH)2, compared to 0.5 to 1 moles NOX removed per 100 moles Ca(OH)2. |
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