BOILER COMBUSTION SYSTEM AND OPERATION METHOD THEREFOR

摘要

To inhibit corrosion of water wall tubes and the like of a boiler and stabilize combustion on a burner during oxygen combustion operation of the boiler. A boiler combustion system according to the present invention includes a boiler 1 equipped with a burner 5 and a two-staged combustion gas input port 9; a flue gas supply fan 29 adapted to extract flue gas from a flue gas treatment system of the boiler via a flue gas circulation line 27; a combustion gas supply line 31, fuel carrier gas supply line 33, and two-staged combustion gas supply line 35 which are branched off from the flue gas circulation line on a downstream side of the flue gas supply fan 29; an oxygen supply line 51 adapted to supply oxygen-rich gas to both the combustion gas supply line 3. and fuel carrier gas supply line 33; combustion air supply fans 43 and 45 installed parallel -to the flue gas supply fan 29 and adapted to supply combustion air; a switching unit adapted to switch operation between the flue gas supply fan and the combustion air supply fans; and dampers 57 and 59 adapted to regulate gas flow rates on the combustion gas supply line and the two-staged combustion gas supply line, respectively.