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Show Apparently the conventional reburning process does not provi de the required environment. An optimized process was designed and tested. The results are presented in Figure 13. In these experiments, the burnout air was split into two streams. The first stream remained at the normal injection location to reduce the CO concentration from 2.5 percent to approximately 0.2 percent. The second stream was injected downstream at a lower temperature, i.e. 1500oF, to complete the burnout. Little improvement over the conventional process was obtained due to the lack of NH3 species at an SR3 of 0.99. However, when an aqueous ammonium sulfate solution was added with the second burnout air to provide the required NHi species 6, an additional 50 percent reduction was dramatically achieved, resulting in an overall reduction of 84 percent in NOx emissions. CONCLUSIONS The experimental results have shown that in the reburning zone the reactant contacting is not rate limiting, the CH radical pool appears to be sufficient, and the Fenimore HCN formation is not of major importance at SR2 = 0.9. In addition, accelerating the decay of HCN in the reburning zone has proved to be ineffective under the available time and temperature environment. The results have also shown that the addition of reducing agents in the reburning zone does not promote the formation of molecular nitrogen. However, the addition of reducing agents, such as anmonium sulfate in the burnout zone can significantly enhance the conversion of XN species to N2 and result in greater than 80 percent overall reduction in NOx emissions. The efficiency of the reducing agent appears to be dependent upon the local stoichiometry and temperature. 8 |