OCR Text |
Show Two stage combustion By this combustion system, the primary air to the burner is kept below the logical air quantity, and the air required for complete combustion is supplied from the position off the burner as the secondary air. With continuous steel heating furnace, reduction of NOx is possible if the burner is the heat equalizing zone is operated somewhat slitching manner and assuring the complete combustion in the preheating and heating zones. This may be regarded a sort of stoichiometric combustion, yet it is a kind of two stage combustion. With heating furnaces,for . Fig. 94 NOx reduction effect by two stage combustion forging;.two stage com--. bustion is possible by provide the secondary air port (NOx port) through S3 the furnace wall. The following is an example of two stage combustion of the furnace for forging with one burner of side combustion in zigzag arrangement on the left wall and two burners mounted on the right side wall. The reduction rate of (Conditions) Furnace temperature: 1350 to 1370°C 02: 1.5 to 3.3% Fuel consumption: 108 to 110¥Kcal/Hr 90 80 70 60 50 Primary air quantity/ Total air quantity(%) 40 NOx by the primary air supply of two stage combustion for this furnace is as shown in Fig. 64, and the operation chart is shown in Fig. 95. In this chart, the furnace is operated by ordinary air ratio with no air supply through NOx port up to 5:15 and is switched to two stage combustion after that realizing about 4 0% NOx reduction by two stage combustion. 8 - 86 - |