Patent ID: 6228214
Filing Date: 2001-05-08
Classification: D21C,F23C,F23G,F23L,Y02E

Abstract:
A method for black liquor gasification in a recovery boiler comprising a lower furnace and an upper furnace, black liquor sprayers for introducing black liquor in the boiler above the lower furnace and a number of combustion air levels, comprising the steps of adding oxygen enriched air to the combustion air or directly into the lower furnace at at least one air level underneath the liquor sprayers to gasify the black liquor and reducing the volume of combustion air fed into the lower furnace so as to have a substoichiometric condition and reduce upward gas velocity underneath the black liquor sprayers based on a constant supply of black liquor into the boiler, wherein the added oxygen and reduced volume of combustion air in the lower furnace substantially reduce the air factor in the lower furnace to a range of about 0.5-0.7 so as to substantially maintain a constant combustion temperature for emission control.