PROCESS constructed a detailed simulation model of a solvent recovery distillation system in preparation for significant process upgrades for several client solvent recovery facilities. This existing distillation system included several complications: the combination of a packed stripping section and a trayed rectifying section; a two-phase liquid overhead byproduct; and a side draw product. Using requested boiling point curve analytical data, PROCESS utilized the simulation software thermodynamics package to develop normal boiling point (NBP) pseudo-component characterizations of the feed, side draw solvent product, bottoms solvent product, and the light overhead and heavy organics byproducts. Using requested process and engineering information, PROCESS was then able to develop an accurate, detailed process simulation of the distillation system.