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Show 3-3 Results of firing test 3-3-1 Behavior of hot air and exhaust gas temperatures Fig. 14 shows the hot air temperature (TA) , cooling air temperature (TAO), combustion gas temperature (TF) and exhaust gas temperature (TE) measured upstream and downstream of the regenerator media. Steam injection may be performed to reduce nitrogen oxides at heat input of 40,000 kcal/h. TA, staring from approximately 850°C just after the changeover, begins dropping in another 30 to 40 seconds to around 620 °C just before the next changeover. This indicates tha t the regenera tor media is gradually losing stored heat. On the other hand, TE, starting from a very low temperature of approximately 120°C just after the changeover, rises to around 680 °C just before the next changeover. This fact indicates that because when the regenerator media has been heated gradually, it looses its absorbing capability. In the regenerative burner described above, TA and TE fluctuate throughout the combustion cycle. Due to these parameter's characteristics, the thermal efficiency and fuel-saving ratio described later are calculated based on the time mean temperature. 3-3-2 Thermal efficiency and fuel saving factor (1) Influence of heat input (without steam injection) Fig. 15 shows the thermal efficiency and fuel saving factor according to changes in heat input between 35,000 and 50,000 kcal/h. Thermal efficiency and fuel saving factor are defined as follows: Thermal efficiency = Fuel saving factor = Heat input - Exhaust heat Heat input Equivarent heat input - Heat input of regene. berner Equivalent heat input x 100% x 100% Where, the equivalent heat input refers to the heat input of the conventional burner (air temperature is 20°C) providing the same effective heat as that of a regenerative burner. As shown in Fig. 15, thermal efficiency and fuel saving factor are 88% and 39%, "respectively, at a design heat input of 37,000 kcal/h. Note that heat input grea ter than the design heat input causes an overload and reduces thermal efficiency. However, since the regenerator media is heated more than expected according to the temperature of the recovered hot air rises, thus improving fuel saving factor. (2) Influence of steam injection Fig. 16 shows thermal efficiency and fuel saving factor when steam injection of 2.186 kg/h is provided. Though the trends in data are exactly the same as when there is no steam injection, they decrease slightly. It is clear that lower heat input causes a larger drop thermal efficiency and fuel saving factor. The reason is that if the heat input is reduced while the steam injection remains the same, the relative ratio of the steam amount against combustion gas amount increases. The thermal efficiency and fuel saving factor are 84% and 36% respectively at a design heat input of 37,000 kcal/h. - 7 - |