OCR Text |
Show reduction effect by steam ejection to the boiler. The NOx reduction shows almost the same tendency as that for boilers. In this case, the NOx reduction tests by two stage combustion and stoichiometric combustion were" alsoo procticed together with steam ejection. The result of the combination between two stage combustion and steam ejection is given in Fig. 97 and that of the combination between stoichiometric combustion and steam ejection is given in Fig. 98. Fig. 97 NOx reduction effect by combination of two stage combustion and steam ejection Furnace temp.: 1380 Or 59 1410°C Gas quantity: 240 59 242 mVHr, <6C) air quantity= air quantity X 0.7 Fig. 98 NOx reduction effect by the combination of stoichiometric combustion and steam ejection S Oral 10- Furnace temp.: 1380 :o 1400°C Gas quantity: 240 to 242m3/nr Vias condition: Air distribution 75:25 Qantity of steam ejection < (kg/10vKcal) Primary air quantity* -totsl air quantity x 0.5 • ±uu00.1 0.2 0.30.40.50.60.70.80.91.0 Quantity of steam ejection (kg/101* Kcal) As shown above, it may possible to obtain such as extra low NOx value as 10 to 20 ppm (O2 11% conversion) by the combination of steam ejection with low NOx combustion. A new combustion boiler installed as the steam source for the ejection or the steam supplied from an exisiting boiler means energy loss itself. It is therefore advisable to install an exhaust heat boiler which uses the exhaust heat of industrial furnace as the heat supply source. 3. Low NOx burner and example of installation Quite a variety of burners are already installed for low NOx arrangement to industrial furnace but most of them are basically two stage combustion system marking a clear contrast with low NOx burners for boilers most of which are self g - 88 - |