OCR Text |
Show 4 3.1.2 Fundamental principle The NOx control principle of this SNT burner is based on the concept of thermal NOx control. (Fig. 3) With the conventional burners, the inside of the quarl becomes locally high in temperature. This is one factor causing a large amount of thermal NOx emissions. With this SNT burner, however, a self-recirculation flow is formed by a strong air swirl and narrow tile to accelerate the air flow. This promotes combustion, contributing to uniformity of flame temperature and enabling stable and perfect combustion with low NOx. Strongly swirled Recirculating flow Promotion of air flow - formation ""- - combustion 0...- r-- Control of NOx Mixture of fuel and air Reduction in average C~mbust i on at r-- promOtion and previous temperature of mixing flame flame low air ratio - Straight narrow Prevention of combustion Prevention of high Stabilization of Quarl f-- i-- - - temperature of - - within Quarl local flame flame Fig. 3 NOx control principle of SNT type burner 3. 1 .3 Characteristics (1) NOx emissions by the SNT burner are 40-70% less than that of the conventional burner. (2) Ignition performance is extremely good, providing stable combustion. (3) This burner adjusts to a wide range of load variations. (4) It works well with low air ratio combustion. (5) This burner is simple and compact in structure, making for easy change of installed burners. (6) It allows for the addition of water of water or steam;joint use of exhaust gas circulation and further reduction of NOx. 3.1.4 Combustion characteristics NOx emission characteristics when burning various kinds of gas fuels and the relationship between furance temperature and NOx are shown in Table 2 and in Fig. 4 respectively. (1) NOx was reduced 50% with fuels of any kind. (2) NOx increased index-functionally together with furnace temperature, and the SNT burner is 60% low in NOx at a furnace temperature of 1250°C. 3. 1 .5 Burner applica tion records The SNT burner has been evaluated as an excellent high thermal efficiency low NOx burner. It has been applied in more than 1000 furnaces, including our company's and other companies' furnaces, and it has shown smooth operation everywhere. The burner application E Q. Q. c· .~ ~ Burner Fuel 0 Conventional tYpe B ~ Conventional tYpe C • SNT type B • SNT type C 500~----------~----------~--------~ 8 100~------==~+-~~'--=~+---------~ <5 ~ 50~----------+-~--~~--+---------~ !:; o z 1200 1300 '400 Furnace tempera,ure (oCI Fig. 4 Relationship between furnace temperature and NO records are are shown in Table 3. The fuel consumption unit in these furnaces is excellent compared with that of the previou~ one. This SNT burner does not show any worse effect as the other low NOx mea~uring onp. iu total energy efficiency. |