| OCR Text |
Show the dependence of NO removal on oxygen concentration for H20 2 injection, even though tests (Figure 2d) demonstrated a slight influence of oxygen. At oxygen level of 4-8%, the modeling predicted complete NO removal in reaction with Irethanol, but at 1 % O2, NO removal decreased and was only about 30%. Methanol reacts with NO in the presence of oxygen since the reaction of CH20H radicals with O2 is one of the chain propagation steps. Modeling of the interaction between NO and the H20iCH30H mixture at different oxygen concentrations had intermediate behavior. SUMMARY AND CONCLUSIONS This paper presents experimental and modeling results on H20 2 and H20iCH30H reactions with NO in a 300 kW combustor firing natural gas and coal. Hydrogen peroxide and its mixtures with methanol can effectively oxidize NO under flue gas conditions. For the three additives: H20 2, CH30H, and their 1: 1 mixture, 90-98% NO removal was achieved in natural gas combustion. At oxygen concentrations between 3 and 8%, there is no significant difference in NO removal. At lower O2 levels the performance is lower especially for methanol. Reconversion of N02 to NO decreases NO control performance by 2-5%, and this effect most likely can be attributed to heterogeneous effects. Optimum injection temperatures are in the range of 870-920 K for methanol and 750-810 K for H20 2 and H20/CH30H mixtures at both natural gas and coal flring. At optimum injection temperatures, H20 2, CH30H, and their mixture are capable of removing 64, 76, and 76% NO from coal flue gas, respectively at an additiveINO molar ratio of 1.5. Two factors are responsible for the difference in performance: the presence of S02 and heterogeneous processes on the surface of fly ash in coal flue gas. NO-to-N02 conversion can be optimized for speciflc application with a certain temperature profile. 16 . |
