OCR Text |
Show Table 3 Characteristics of gas and oil combustion Gas combustion Oil combustion Combustion range (turn-down ratio) 1 : 7 -10 1:3-5 Gas has a wide range of com- The combustion quality bustion because of the good is poor and uniform combustion quality and easy mixing of oil drops mixing property with air. and air is hard. Air ratio for complete combustion 1.05 - 1.10 1.20 -1.40 Furnace ambient All of oxidized ambient neutral ambient and reduced ambient are acceptable. In most cases, the ambient is oxidized with excessive air. Frame shape Load on combustion chamber Ignition quality All of long, short and flat Comparatively long shape of frame are acceptable, frame only 100 -300 thousand Kcal/Nm3h Good 30-150 thousand Kcal/ Nm3h No good After going through the following steps, the low NOx cumbus-tion technology for boilers with city gas has now reached the stage of the application to new boilers intended for compact sizing and energy saving (high efficiency). Basic research and development of low NOx burner with test furnace Low NOx combustion with actual boiler (forced exhaust gas recycling combustion) Low NOx burner test with actual boilers (mainly with forward flow combustion boilers) Development and actual boiler test of low NOx burner for return combustion - Standardization of low NOx burner for package boilers by boiler makers In the following pages, low NOx technology for city gas with actual boilers and the effects are outlined. e - e- |