Process for recovering crude tall oil

Abstract

A process and apparatus for recovering crude tall oil are disclosed. Acidulation of a crude tall oil soap stream generates a spent acid stream that comprises lignin and entrained crude tall oil. By subjecting the spent acid stream to dissolved gas flotation, a lignin phase comprising entrained crude tall oil can be recovered and causticized, resulting in recovery of most of the crude tall oil that was present in the spent acid stream. A clarified spent acid stream is also generated, which can be treated with caustic and utilized for a soap washing process that integrates easily into the overall CTO recovery process. The apparatus comprises a crude tall oil acidulation unit, a dissolved gas flotation unit, a causticizing unit, and a soap separation unit. The inventive process marries dissolved gas flotation, a well-known water treatment process, with causticization of a recovered lignin phase, a step known from batch acidulation, to improve overall tall oil recovery from a continuous process.

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