| OCR Text |
Show 3.2.5 Results of combustion experiment (1) NOx emission Two staged combustion method which was 200 able to be achieved only by devising the "g burner structure was adopted to lower N O x j| emission. The relation between N O x concen- 0*120 tration and temperature of the furnace is shown S- ^ 80 Fig. 14. From this figure, the N O x concentra- x tion was able to achieve 130ppm or less at z 40 1300°C, which was the highest temperature of the furnace, which satisfied the regulations HK Limit of Emission 160ppm •130ppm O2=1.0% 0 1100 Fuel=COG+LDG 1150 1350 1400 value enough. (2) Heat recovery characteristics 1200 1250 1300 Furnace Temp.fC] Fig.14 NOx characteristic of direct firing regenerative burner Fig. 15 shows the heat recovery characteristic of the burner. From this figure, heat recovery rate achieves very high, 8 0 % or more. And heat recovery ratio becomes lower with decrease of waste gas ratio exhausted from regenerator. But quantity of recovered heat (heat reuse ratio) is decreased because the gas exhausted from regenerator decreased. Moreover, when the waste gas ratio exhausted from regenerator lowers, the temperature of exhaust gas decreases below the acid dew point and the low temperature corrosion might be come a problem. So it is advantage in heat efficiency to exhaust waste gas from regenerator as much as possible. In the commercial operating burner, above mentioned high efficiency control system was adopted and it was able to optimize the exhaust gas ratio regardless of the burner combustion load. 100 •0200 20 40 60 80 100 Waste Gas Ratio Exhausted from Regenerator[%] Fig. 15 Heat recovery characteristic of direct firing regenerative burner 3.2.6 Installation of regenerative burner to commercial operating furnace (1) Outline of installation Schematic of the wide flange beam mill furnace and installation of regenerative burner is shown in Fig. 16. This furnace is eight zone type walking beam furnace of 220t/hr. Regenerative burner system was installed to lower part of No. 1 and 2 heating zone as the side burners by 4 pairs each. The capacity of the burner is 5,800W/burner. and it is the biggest burner capacity in Japan and also the biggest class in the world. |
