METHOD OF CONTROLLING DRY TYPE LOW NOX BURNER

摘要

PURPOSE:To improve the thermal efficiency and reliability of the burner by transiting the combustion state of a flame within the burner from a diffusion combustion to a premixing combustion by use of a flame diluting agent (inert gas) or a flame elongating agent (fire-extinguishing agent). CONSTITUTION:A fuel 13 is burnt by a diffusion flame 14 as heretofore from the starting time to a transition load whereby the level of NOx concentration is increased monotonously. When the transition load is reached, a flame elongation agent pan 15 is injected and a flame 16 is gradually elongated and caused to reach a recessed part 17 of a main chamber 5. Further, the quantity of the elongation agent is increased, and finally the flame 16 is driven out into the main chamber 5. The transition load is selected at an air-fuel ratio at which a premixing combustion is possible, that is, close to a so-called combustion limit. A flame 18 which has been driven out to the main chamber 5 becomes a premixed flame 18, because an auxiliary chamber 3 becomes a premixing chamber, and the NOx concentration level is greatly lowered. When the load is lowered and reaches the transition load to the diffusion combustion from the premixing, an ignition plug is excited within the auxiliary chamber 3, and a mixed gas 19 is ignited and returned to a diffusion flame 14.