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Show 5 Table 2 NO emission of various gas fuels (3%02 conversion, ppm) LPG Coke Blast Conventional SNT type Reduction ratio Fuel over gas (%) (%) furnace gas type burner burner (%) (%) A 100 0 0 360 180 50 B 27 0 73 260 135 48 C 13 0 87 140 70 50 D 0 100 0 350 150 57 E 0 45 55 100 50 50 Table 3 Applications of SNT burner to different types of heating furnaces Type of Capacity of NOx ReductioI"' Equipment Fuel burner emissions ratio furance (103 kcal/n. p) (11% 02 ppm) (%) !pusher L.S.C. heavy oil- 2000 - 4000 30 54 M2500 ~fularnb achee ating ~alking beam L.S.C. heavy oil-coke 2000 - 4000 55 42 oven gas Pit Coke oven gas 2000 82 60 Billet heating Rotary furnace furnace Lov.Sen.C .g ahse avy oil-coke 450 - 1500 45 - 30 40 lPipe heat Walking beam Koveerno segnaes oil-coke 150 - 600 15 50 itreatment ~urnace Barrel Coke oven gas 150 - 300 70 50 3.2 SSF burner6)-7) This burner was developed to obtain excellent combustion ~ith eithe~ pulverized coal n= heavy oil. There are two types of burners, short flame type and long flame type burners. 3.2.1 Structure of burner When pulverized coal is ejected from the burner center axle, the burner becomes a long flame type burner (center coal burner). On the other hand, when auxiliary fuel and pulverized coal are ejected from the burner center axle and circularly from its external circumference respectively, the burner become a short flame type burner (intermediate coal burner). Strongly swirled secondary air and tertiary air are ejected from the air holes in the external circumference and circumferentially from the external circumference of quarl respectively. (Fig. 5) 3.2.2 Principle and characteristics of burner This SSF burner is a high efficiency, low NOx burne~). It is a two-stage combustion type burner in its fundamental structure, and it has an exhaust gas self recirculation function. In its first stage, char is rapidly pyrolyzed and gasified by the heat after rapid combustion of coal voltalization, and in the second stage its gas is burned. (1) Step-wise supply of air During primary stage combustion, an improvement in ignition and rapid combustion are promoted by a limited supply of air, which is necessary for perfect combustion of a volatile portion great in combustion rate. Over-cooling is prevented. (2) Strong swirl to secondary air The ignition and combustion is stabilized by a mixture promoting effect, and NOx emissions are reduced. Secondary air Teaniary air Pulverized fuel () () {} Mixed combustion fuel Swirling impeller .' .,/ ~.~.. prom:oter (cho::k'e"')' ';n' Fig.5 Structure of SSF burner (lntemlediate coal) |
