OCR Text |
Show the following chapter. Reduction of air pre-heating temperature Energy saving for boilers is one of the three main theme of boilers (safety, energy saving and environmental preservation) , and for the purpose, the exhaust heat is often recovered by increasing the air temperature for combustion with an air-heater. Pre-heating of combustion air, however, is a factor to increase NOx, as a matter of course. Fig-10 is the summary of NOx concentration using various data of pre-heated air temperature and normal air temperature for comparison. Fig#10 Air temperature and NOx concentration 130 120 U0 100 • • A O • toller capacity 24c/h 0.4c/h 3 t/h Bollar typs Water cube type Once-chroufb type Plre tube type Burner type C type burner CKT-5 ClD-25 Coabuetlon chaaber thermal load 71x10* Kcal/e'h 50x10* Kcal/e'h lSoxip* Kcal/e'h 84x10* Kcal/e'h 84x10* Kcal/e'h load ratio 100Z 701 100Z 100Z 100Z recti rata 0 0 0 0 15Z 80 70 60 50 40 30 20 10 Ml 60 90 120 ISO 180 CoabuatIon air teeperature (*c) 240 270 8 -15 * |