Recycling vs. reprocessing. Optimization of agossypol production process

Abstract

Three processes to obtain GAA from the soapstock residue of oil refineries were compared inthis work. The first process is the originally proposed by Dowd and Pelitire (2001. Ind. CropsProd. 14, 113) in which the mother liquor from the last crystallization step still containsan appreciable amount of gossypol which is lost as a process residual stream. The secondprocess recycles the mother liquor to the hydrolysis first step of the process, following theheuristic of the traditional process design procedure by Douglas (1988. Conceptual Design ofChemical Processes. McGraw Hill, New York, NY), which increases product yield. While thethird process adds a new downstream processing line to reprocess the mother liquor. Thislast alternative renders a slightly lower product yield than Process 2 but requires a smallerinvestment cost, exhibiting the best economic performance.The alternative of incorporating a recycle to reprocess unreacted material (in this casethe bound gossypol present in the crystallization mother liquor) is the usual approach intraditional process design. However, in this particular study case, it does not succeed inrendering the process alternative with the best economic performance: the recycle streamflow impacts on the equipment sizes, increasing investment cost far beyond the alternativethat adds smaller units to reprocess the mother liquor stream.