| 摘要 |
<p>PURPOSE:To reduce a power amount through minimization of given circulating exhaust gas amount and to inhibit production of soot during low NOX combustion, by a method wherein circulating exhaust gas is properly distributed to a burner at each stage so as to reduce generation of NOX, and steam is sprayed to a very low air-fuel ratio burner. CONSTITUTION:Circulating exhaust gas in a mixing ratio GM indicated by a formula of GM=21-X/X-Y (-), wherein X is O2 concentration (dry vol%) in window box, (Y) is O2 concentration (dry vol%)in combustion exhaust gas, is mixed in air for combustion of each burner and/or each burner stage, and steam or water is fed to fuel or gas for burner at a topmost stage or/and having a lowermost air-fuel ratio or at a burner stage. Thus, the exhaust gas recirculating (GM) ratio of a high air ratio burner is increased, meanwhile, GM to a low air ratio burner is decreased. Thereby, waste of GM theretofore excessively fed to a low air ratio burner can be eliminated. Besides, since the optimum air ratio of each burner is hourly fluctuated by each load band, provi sion of function to control the fluctuation enables reduction of the power of a GM fan. Further, an increase in steam concentration in combustion region further inhibits production of soot.</p> |
