Methods of improving productivity of black liquor recovery boilers

摘要

Methods of increasing the throughput of recovery boilers equipped with at least two levels of injection of air, the methods improving the thermal efficiency of the boiler with oxygen enrichment of the air in at least one level of the combustion air system, at or above the secondary air level. In one method, a black liquor recover boiler having two levels of air injection is retrofitted with a third level of oxidant injection below or at the same level as the original secondary air, and oxygen enrichment is applied to at least the original secondary air stream and the third level air stream. A preferred method is for the third level to be placed at or close to the same level as the black liquor injector ports.