Patent ID: 8393065

Claim:
A method for retrofitting a pulverized coal boiler in an air combustion boiler system having a plurality of burners over a plurality of stages along the vertical direction on a wall surface of a furnace of the pulverized coal boiler and an after-air port for introducing air for two-stage combustion located above the burners to retrofit into a two-stage combustion pulverized coal boiler in an oxyfuel combustion boiler system, wherein installing an air separation unit for separating oxygen from air and a CO 2 recovery device for absorbing and separating CO 2 gas from combustion exhaust gas generated in the boiler furnace, wherein the method for retrofitting the combustion pulverized coal boiler is comprising the steps of: stopping to supply fuel into the furnace from a burner located in a middle stage among the plurality of stages of burners installed on the wall surface of the furnace of the pulverized coal boiler; installing a new burner to an opening of the after-air port provided on the wall surface of the furnace of the pulverized coal boiler; and installing a supply line to introduce the oxygen manufactured by the air separation unit and part of the recirculation gas, which is part of the exhaust gas exhausted from the pulverized coal boiler, circulated into the pulverized coal boiler, to the plurality of stages of burners except for the stopped burner and to the new burner installed to the opening of the after-air port through the supply line, and supplying the oxygen and the recirculation gas from the plurality of stages of burners and the new burner into the furnace.