OCR Text |
Show Optimum design Intense mixing of combustion air with plenty of burned gas in the furnace, which is brought by high momentum ejection of combustion air, yields distributed reactions and lowers flame temperature significantly. This combustion regime in low concentration of oxygen can be sustained only by the supply of highly preheated air. If air of ambient temperature is supplied, the flame will be extinguished instantly. Therefore, in addition to the use of highly preheated air, the intense mixing of the air with a plenty of burned gas before combustion is essential for reduction of NOx. We used to think that the burner design is an independent technology and a furnace equipped with a well-designed burner is a good furnace. However, it is not always true because the design of n e w concept furnaces described above requires total optimization of the system as a reactor. Burners should be designed taking account of the global flow field, mixing, combustion, heat transfer in the furnace. Regenerative burner Water Fig.8 Boiler with optimized regenerative burner system (schematic). |