OCR Text |
Show For example, as shown in Fig. 9, when the combustion rating of the PAX-R burner is throttled, a low N O x value equivalent or lower than those of the above mentioned ultra low N Ox regenerative burners may be achieved. It is thought that this results from the relatively greater distance between the main gas injection outlet and the secondary air injection outlet when the combustion rating is decreased. This is to say that if the "compactness" condition is removed, then N O x value may be substantially reduced. 2.5 Serializing of the PAX-R burner Including the model in the above application case, four models of PAX-R burners with nominal capacities of 580, 830, 1400, and 2100 k W were developed. Centering around forge furnaces, 20 pairs were made practical. 2.6 Further reduction of NOx emission by the PAX-R burner To attempt further reduction of NOx emission by the PAX-R burner while maintaining the concepts, an eccentric type incorporating thick and thin fuel combustion was made on trial and tested. The upper two main air injection outlets of the four outlets of the PAX-R burner were closed and to maintain the concept of low pressure loss, the total cross sectional area of the two lower injection outlets were made to equal the total cross sectional area of 4 outlets. The test results are shown in Fig. 10. These measurements showed that temperature distribution in the axis direction became more uniform. Also it was visually confirmed that a part of the flame, after curling up, was again engulfed by the flame. From this, it is believed that recirculation of exhaust inside the furnace was promoted and emission of N O x emitted at the main flame part was suppressed. As the result, it was possible to reduce the N O x value by approximately 3 0 % compared with the normal type. Furthermore, in addition to shortening the flame length by approximately 3 0 % , it was possible to realize compactness of burner tiles. Furnace temperature = 1290*^, Hereafter, a PAX-R burner Combustion rate = 1200 kW. Air ratio = 1.1 of this type will be applied to a forge furnace to confirm performance. P '1 1350 E o 1250 3 2 | 1150 CD Normal type ^ ^ '-••--^-• > ^ - - - L ^r Eccentric type i 2000 4000 Distance from burner mm Fig. 10 Comparison of the PAX-R burner flame temperature distribution |