Experimental Study on NOx and N20 Emissions from a CFB Combustor

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could be controlled by adjusting the primary air stoichiometry and temperature in the lower part of the riser. The resulted N20 emission could then be reduced by increasing the local temperature, or by adding catalytic material, at the exit of cyclones. CONCLUSIONS Experimental results show that (1) the NOx emission increases whereas the N20 emission decreases with increasing temperature; (2) both NOx and N20 emissions increase with increasing excess air level, and (3) the emission of NOx could be effectively controlled by air staging. In order to minimise NOx and N20 emissions from a CFB, the control of the emission ofNOx and N20 has to be carried out in stages. ACKNOWLEDGEMENT The research work described in this paper was carried out with the financial support of the Science and Engineering Research Council. REFERENCES Amand, L. E. and Andersson, S. (1989). Emissions of nitrous oxide from fluidized bed boilers.Proceedings of the 10th Int. Conf. on FBC, San Francisco, USA, ASME, 49. Asai, M., Aoki, 1(., Shimoda, H., Makino, 1(., Watanabe, S. and Omata, I(. (1990). Optimization of circulating fluidized bed combustion. Proceedings of the 3rd Int. Conf. on CFB, Nagoya, Japan, 379. Basak, A. 1(., Sitkiewitz, S. D. and Friedman, M. A. (1991). Emission performance summary from the Nucla circulating fluidized bed boiler demonstration project. Proceedings of the 11 th Int. Conf. on FBC, Montreal, Canada, 211. Boyd, T. J. and Friedman, M. A. (1990). Operations and test programme summary at the 110 MW Nucla CFB. Proceedings of the 3rd Int. Conf. on CFB, Nagoya, Japan, 297. Gavin, D. G. and Dorrington, M. A. (1993). Factors in the conversion of fuel nitrogen to nitric and nitrous oxides during fluidized bed combustion. Fuel, Vol. 72, 381. Gierse, M. (1990). some aspects of the performance of three different types of industrial circulating fluidized bed boilers. Proceedings of the 3rd Int. Conf. on CFB, Nagoya, Japan, 347.