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Show 1. Introduction The regenerative burner system has been widely used to reduce the energy consumption in high temperature industnal processes. The system promises high thermal efficiency with a newly developed heat recovering technique using a compact ceramic regenerator. Despite its high thermal efficiency, the regenerative burner system faces a problem of thermal N Ox emission. To reduce N O x emission from the regenerative burners without losing efficiency, Tokyo Gas has developed an innovative FDI (Fuel Direct Injection) low N O x combustion technology" H3>. The FDI technology features direct injection of fuel into a furnace chamber, with combustion air separately injected (Fig.1). Fuel and air jets induce a large amount of combustion products before being mixed and ignited, generating a low temperature lazy flame. N O x emission is substantially reduced. At an operating furnace temperature of 1300°C, the FDI flame demonstrates N O x emission of 150ppm (02=0%), much lower than conventional regenerative burners. The FDI low N O x technology is expected to boost the application of the regenerative burner system to a wide variety of industrial furnaces. When applying the FDI regenerative burner system to industrial furnaces, a number of new design parameters specific to the system need to be taken into account. The effect of switching-over flames generated by the regenerative burners on heat transfer characteristics are of great concern to optimize the configuration and operation of furnaces. The effect of unique flames generated by the FDI combustion needs to be carefully considered. Due to lack of experience with the FDI regenerative burner system, detailed knowledge and insight of the system is required. A trial-and-error approach used to be the only way to optimize these parameters. With the growth of C F D technology, a 3-dimensional detailed numerical analysis has become one of the most promising tools to facilitate the design. Tokyo Gas has developed a 3- dimensional numerical simulation method to design and optimize innovative industrial furnaces such as the one equipped with the FDI regenerative burner system4'. The method is capable of predicting complex heat transfer phenomena generated by flow, combustion, thermal conduction and radiation to encourage intelligent design of innovative high performance furnaces. This paper describes the numerical method used to optimize a muffle type continuous heat treating furnace for the bright annealing process of a steel strip. The paper also introduces an overview of 'if-Diss' (Industrial Furnace Design Intelligent Support System), which features a state-of-the-art numerical method with a powerful database of various analytical models and a useful grid generator to allow interactive preprocessing for the numerical simulation. |