OCR Text |
Show 4) TCG burner This is the low NOx burner for city gas combustion designed to match the combustion chamber of return combustion type fire tube boilers, and for the low NOx arrangement, the effect of two stage combustion and of stoichiometric combustion are multiplied while taking the exhaust gas self re-circulation combustion as the base. As shown in Fig. 29 Shcematic drawing of TCG burner Coabuaclon "\ } t gaa ' it Ignition gaa, f Unitioo air i Primary •••• Frtaarr and aacoaaary air I Tertiary air the schematic drawing of Fig. 29, the NOx suppressing mechanism is in the following combination. ° Self exhaust gas re-circulation method....By the venturi effect of the fuel gas ejection through the nozzle at a high speed, combustion exhaust gas in the furnace is absorbed' to be mixed with fuel gas for reduction of 02 concentration and flame temperature. ° Stoichiometric combustion method Two combustion zones of fuel excess and air excess are formed to lower the flame temperature as a whole. i. ° Multi-stage combustion method With thin film of ring form, a flame of large surface area is formed to increase the radiation heat from the flame so as to lower the flame temperature. Because of the over-all NOx suppressing effect, this burner is called Total Combustion Control Gas Burner, or TCG burner in short. By the multiple effect of steam ejection of 3 0 to 40 ppm, NOx can be lowered to 20 - 25 ppm with city gas(both 6C and 13A) at 02=5% conversion. B - 30 - |