476 / 2018-12-31 11:03:01

Study on Effects of Syngas Additive on NH3-SNCR Reaction

Denitrification, SNCR, syngas, additive, fluidized bed

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Due to the large variation of operating load of fluidized bed boiler, the selective non-catalytic reduction denitrification technology (SNCR) faces the problems of low reaction rate and high ammonia escape rate due to the limitation of reaction temperature window. Therefore, the NH3- SNCR denitrification reaction with gasification syngas was studied in the paper. Through experiments and simulation calculation of SNCR elementary reactions with syngas, the variation of SNCR denitrification reaction characteristics was studied with varying the influencing factors such as ammonia-nitrogen ratio, reaction residence time, type and concentration of additives. The results show that there is a weak synergistic effect between the concentration of syngas and the reaction residence time, while the synergistic effect of syngas additive and ammonia-nitrogen ratio is strong. With the increase of syngas concentration, the effect of ammonia-nitrogen ratio on SNCR reaction is gradually strengthened, and the ammonia needed to achieve the same denitrification efficiency can be reduced. Therefore, although syngas cannot completely replace ammonia reductant in the removal rate of NOx, the presence of syngas can accelerate the reaction rate and shorten the reaction residence time in a certain range, while allowing appropriate reduction of ammonia-nitrogen ratio and reduction of ammonia escape.