Kinetic Model and Simulation of Promoted Selective Non-catalytic Reduction by Sodium Carbonate

摘要

The detailed kinetic model of selective non-catalytic reduction (SNCR) of nitric oxide, including sodium species reactions, was developed on the basis of recent studies on thermal DeNO_x mechanism, NO_xOUT mechanism and promotion mechanism of Na_2CO_3. The model was validated by comparison with several experimental findings, thus providing an effective tool for the primary and promoted SNCR process simulation. Experimental and simulated results show part-per-million level of sodium carbonate enhances NO removal efficiency and extend the effective SNCR temperature range in comparison with use of a nitrogen agent alone. The kinetic modeling, sensitivity and rate-of-production analysis suggest that the performance improvement can be explained as homogeneous sodium species reactions producing more reactive OH radicals. The net result of sodium species reactions is conversion of H_2O and inactive HO_2 radicals into reactive OH radicals, i.e. H_2O+HO_2=3OH, which enhances the SNCR performance of nitrogen agents by mainly increasing the production rate of NH_2 radicals. Moreover, N_2O and CO are eliminated diversely via the reactions Na+N_2O =NaO+N_2, NaO+CO = Na+CO_2 and NaO_2+CO=NaO+CO_2, in the promoted SNCR process, especially in the NO_xOUT process.