Fig.13 shows the influence of reheat on NO/NOx in case that methane was reheat fuel (reheat load: 36kW). Without hydrogen for the improvement of the combustion efficiency, NO/NOx descended remarkably with the reheat, while only a slight change of NO/NOx (about 10%, the almost same level as that in the case of pure hydrogen reheat, shown in Fig.12) was found in the case that hydrogen was added. Unburned elements in the pure methane reheat seem to cause this difference.

　

Fig.10 NOx Emission Indices of Methane

Fig.11 NOx Emission Indices of Hydrogen Methane Mixture

Fig.12 Change of Ratio of NO to NOx by Reheat (Reheat Load of Hydrogen = 36kW)

Fig.13 Change of Ratio of NO to NOx by Reheat (Reheat Load of Pure Methane and Mixture = 36kW)

　

3. CONCLUSION

　

The experiments on combustion characteristics of the reheat process in a high temperature wind tunnel with hydrogen combustion gas stream were carried out using hydrogen and methane as reheat fuel.

Primary results are as the following:

1) The combustion efficiencies of the hydrogen for the internal reheat were almost 100%, while these of the methane were much lower. For the improvement of the combustion efficiency of the methane in reheat process, addition of hydrogen was effective.

2) The emission index of NOx in the reheat process with hydrogen increased along with the inlet temperature but it was much lower than that of the main combustor and of combustion with methane mixture with 20% hydrogen.

3) The ratio NO/NOx decreased by the reheat process and this tendency was more remarkable at a lower inlet temperature of the reheat section. Also in case of pure methane reheat, notable descend of this ratio was observed.

　

REFERENCE

　

[1] F. Joos, P. Brunner, B. Schulte-Werning, K. Syed, A. Eroglu, Development of the Sequential Combustion system for the ABB GT24/GT26 Gas Turbine Family, ASME paper 96-GT-315 (1996).

[2] Kan S., Morishita T., and Hiraoka K., Reheat Gas Turbine with Hydrogen Combustion between Blade Rows, Proc. of 1983 Tokyo International Gas Turbine Congress, 83-Tokyo-IGTC-27 (1983).

[3] Hiraoka K., Kan S., Kumakura T., M., Ikame, Harumi K., Shirota H. and Morishita T., Study of Internal Reheat Hydrogen Gas Turbine, Proc. of 1995 Yokohama International Gas Turbine Congress, 95-YOKOHAMA -IGTC-84 (1995).

[4] Harumi K., Kan S., Hiraoka K., Ikame M., Shirota H. and Morishita T., Study of Internal Hydrogen Reheat Gas Turbine, Journal of Gas Turbine Society of Japan, Vol.26 No.101 (1998), pp.107-114 (in Japanese).

[5] Nomura M., Tamaki H., Morishita T., Ikeda H., and Hatori K, Investigation of Operating Performance of a Small Gas Turbine with Hydrogen Fuel, Report of Ship Research Institute, Vol. 18 No.2 (1981), pp. 1-18 (in Japanese).

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