Abstract
The urea-based selective non-catalytic reduction (SNCR) process is widely favored for its significant economic advantages over selective catalytic reduction. However, in most real-world applications, it often falls short of reaching the required high-efficiency temperature range. Alkali metals are recognized as potential promoting additives for higher de-NOx efficiency and wider temperature window. The effects of individual additives have been widely studied, but the combined use of Na/K additives has not been extensively investigated, particularly with regard to their underlying mechanisms. This paper explores the promoting mechanism of Na/K on the urea-based SNCR process, and propose a synergistic enhancement mechanism for the combined use of Na/K additives. Results showed that the Na/K additives into urea significantly improve the de-NOx efficiency, especially in a low temperature range of 600–1000 °C, which indicating a much wider effective temperature window. Na/K combined additives (Na2CO3 + K2CO3 and Na2CO3 + CH3COOK) exhibit a strong and synergistic promotion of urea-based SNCR efficiency. These combined additives effectively broaden the lower limit of effective temperature window from 950 °C and 804–892 °C to 774 °C compared to the none-additive and the single-Na or K additive conditions. Notably, the de-NOx efficiency of combined additives reaches 3–4 times of that non-additive conditions at relatively low temperatures, and the ammonia escape and N2O emission is respectively reduced by ∼ 1/3 at 600 °C and ∼ 1/2 at 800 °C. This study can provide a deep insight into the enhanced urea-based SNCR efficiency by Na/K combined additives and enhance the feasibility of urea-based SNCR technology under lower temperatures.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call