Patent ID: 6799526
Filing Date: 2004-10-05
Classification: D21C,F23G,F23L,Y02E

Abstract:
A method of controlling the oxygen concentration in the flue gas of a recovery boiler, the method being applicable to boilers with three levels of air injection, the method including the steps of:a) supplying oxygen flows to at least two air injection levels of the recovery boiler, the two air injection levels being different from the primary air injection level, for oxygen enrichment of the two air injection levels; b) generating a flue gas by burning black liquor in a combustion zone of the recovery boiler; c) selecting a set point oxygen concentration; d) sensing the oxygen concentration in the flue gas; e) adjusting the oxygen flow injected in the tertiary air injection level, in order to maintain the sensed oxygen concentration at the set point oxygen concentration, while maintaining the flow of oxygen in the secondary air injection level constant.