The behaviors of alkali metal hydroxides and chlorides released from biomass for NO reduction during biomass rebuming were analyzed. Na-Containing species have great promotion of NO reduction by controlling the free radicals of H and OH, as compared to K-containing species, and the effects of alkali metal hydroxide vapors and alkali metal chloride vapors on the NO reduction rate were identical. At the beginning stage of biomass rebuming, Na-containing species can effectively inhibit the conversion of HCN into NH, HNO, and N by controlling the formation of H and OH, and it avoids NO formation. At the later stage of biomass reburning, the free-radical levels of H and OH reach equilibrium, Na-containing species can promote the formation of H and OH to sustain a relatively high level through the chemical reaction path of NaOH -> Na -> NaOH, and NO is effectively reduced. Because the reaction rate constant of K + OH = KOH is only (1)/64 of Na + OH = NaOH, KOH has low promotion of NO reduction, as compared to NaOH.

This paper was published as:
Li S, Wei XL. Behavior of Alkali Metal Hydroxides/Chlorides for NO Reduction in a Biomass Reburning Process. ENERGY & FUELS, 25(8):3465-3475(2011)