Solvent sublation for waste minimization in a process water stream - a pilot-scale study

Solvent sublation, an adsorptive bubble separation process, was carried out on a pilot scale to separate dilute concentrations (30-100 ppmw) of naphth alene from a process water stream at a temperature of 140 degreesF The test was conducted at the Borden Chemicals and Plastics (BCP) acetylene plant s ite located in Geismar. Louisiana. A carbon steel column of 6 " i.d. and 17 ' high was constructed. White mineral oil supplied by Texaco Inc., was used as the organic solvent for solvent sublation. A special annular shear spar ger was used for nitrogen gas sparging into the vessel. The process was con ducted in two-phase continuous and three-phase continuous modes. The naphth alene recovery from the process water was independent of the oil flow rate, but depended on the nitrogen-to-water flow rate ratio. The release of naph thalene to the overhead gas space during the solvent sublation process was substantially less than that during conventional gas stripping. The improve d performance of solvent sublation over both conventional gas stripping and solvent extraction operations was apparent. (C) 2001 Published by Elsevier Science B.V.