Experiment and Mechanism Analysis of Selective Non-Catalytic Reduction with the Compound Reducing Agents in a Lab-scale CFB Reactor

The conventional SNCR technology with reducing agent ammonia has been utilized in power industry extensively. In this paper, a new denitrification method with the compound reducing agents contain ammonia and reducing gas was discussed. The SNCR experiment with H₂ and CH₄ as the additives was carried out in a lab-scale CFB reactor which imitated flue gas environment in CFB boilers, meanwhile the mechanism modelling including the reaction of gas additives was adopted to simulate the experimental process. The validations of mechanism modelling and parameter optimizations were discussed by the comparisons of experimental and computational results. The compound reducing agents with H₂ and CH₄ additives can expand the adaptive temperature window of denitrification reaction and reduce the optimal reaction temperature. Hence the NOx removal efficiency of conventional SNCR can be improved significantly, and the effect of H₂ additive is better than that of CH₄ additive. The optimal reaction temperature in simulation is about 800°C with the H2 concentration of 300 ppm, while 760°C under the concentration of 900 ppm. The minimal NOx residual concentration is estimated to approach 75 mg/m³ at 800°C by using the H2 compound reducing agent. (paper)