Kraft Smelt Solidification In A Fluidized Bed Reactor

Abstract

An improved black liquor recovery system for use in a kraft pulping mill is provided. Molten kraft smelt from a black liquor recovery boiler or recovery system is fed into a fluidized bed reactor where it is cooled and solidified to form solid kraft smelt particles. The solid kraft smelt particles are then fed into a dissolving tank containing an aqueous solution to form a green liquor. The green liquor, after clarification, is treated with lime to form a white liquor containing the regenerated pulping chemicals. Waste steam is an especially preferred fluidizing gas for use in the fluidized bed reactor. This process provides improved energy recovery and process productivity, reduction in gaseous sulfur-containing emissions, reduction in landfilled wastes, and improved safety as compared to a conventional kraft smelt treatment process.