method and apparatus for treating pulping process waste liquors

摘要

A method and system for treating waste liquors from pulping processes for recovering energy and chemicals from the waste liquors (such as kraft black liquor). A recovery boiler having a furnace for combusting waste liquor includes a plurality of injection nozzles in the furnace walls, for injecting waste liquor into the furnace. At least one conduit is disposed in at least one wall of the furnace below the nozzles for withdrawing a portion of the combustible gas from the furnace. Typically between about 10-50% of the combustible gas produced in the furnace is withdrawn through the conduit or conduits below the nozzles, and the withdrawn gas is cooled and purified. The system may utilize a superheater which is separate and distinct from the recovery boiler, the cleaned and cooled withdrawn gas led to the separate superheater.