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Show • 1 PAPER NO. 9E. High Temperature Excess-enthalpy Combustion for Efficiency Improvement and NOx Abatement Toshiaki HASEGAWA and Ryoichi TANAKA Nippon Furnace Kogyo Kaisha Ltd. Shitte 2-1-53, Tsurumiku, Yokohama, Japan Ken KISHIMOTO Faculty of Engineering, Kokushikan University 4-28-1, Setagaya, Setagaya-ku, Tokyo, Japan ABSTRACT New development utilizing an excess-enthalpy combustion technology has been carried out in order to increase thermal efficiency in industrial furnaces while reducing NOx emissions. High Temperature Excess-enthalpy Combustion, a technology using high calorific fuel and high temperature air preheated by its own flue gas, consists of two distinguished characteristics; effective waste-heat recovery using a regenerative heat exchanger and combustion using air preheated to higher than 1000 degree Centigrade. Utilization of High Temperature Excess-enthalpy Combustion combined with high flow rate gas recirculation lowers the maximum combustion temperature and provides a uniform temperature profile in furnace. This improves thermal efficiency and helps to control NOx emissions by reducing the maximum flame temperature without causing unstable combustion. The basic characteristics of the heat transfer resulted from this advanced combustion and heating method, has been investigated by using a simple heat balance calculation. 1. INTRODUCTION High temperature excess-enthalpy combustion has potential for producing high thermal efficiency and low NOx emissions in industrial furnaces. This was first proposed in a paper by the authors (1) in 1993, where a method was described for obtaining uniform heat flux profile. High combustion flame temperature has to be controlled to permissible level for the furnace material since excess enthalpy combustion generally causes flame temperature to rise. The method presented in the paper was to alternate combustion periodically using two or more burners or mechanical shift of the burner. |
