| OCR Text |
Show - 2 - the base of its regenerator. exhaust gas is drawn through the other burner and down into its associated regenerator to preheat the pack i ng, then discharged to the atmosphere. When the regenerator being heated is sufficiently charged. the reversing system operates, cold air flows to the newly heated regenerator and is preheated, the previously cooled regenerator being reheated by the exhaust gas from the other burner firing. The regenerative burner shows a high heat recovery efficiency of 80-95% , the combustion air is preheated to over 1000°C. This results in a problem of very high NOx emission concentration in the industrial furnace. Shigeta et al. (1991) has developed FOI (Fuel Oi rect Injection) for high temperature furnaces. The NOx level with FDI is about 35ppm ( 11 '" 0 2 ) wit h 650°C pre h eat e d air un d e r 1 300°C fur n ace t em per a t u r e . Suzuki et al. (1982 , 1984) developed two high efficiency burners{model E and model EE), which are fully compatible with energy saving and with low NOx emisson. The model EE burner was confirmed to be very suitable for use as the regenerative burner to reduce NOx emisson in the industrial furnace. 2. PRINCIPLE OF COMBUSTION OF LOW-NOx BURNER Figure 1 shows the principle of combustion of the KOBELCO (Model EE) low-NOx regenerative burner. The direction of fuel injection is at the angle of "a" to the air stream axis, the combustion air is injected separately insymmetry with the fuel stream axis to be at an open angle of " e". The mixing of fuel and combustion air in the primary combustion zone is I imited, and combustion occurrs under fuel rich conditions in the primary combustion zone. Fuel which is not burned in this zone gradually mixes with air not used in the initial stages and thus combustion is completed. Self-recirculation of the flue gas is thus achieved. |
