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

Abstract

Solvent sublation, an adsorptive bubble separation process, was carried out on a pilot scale to separate dilute concentrations (30–100 ppmw) of naphthalene from a process water stream at a temperature of 140°F. The test was conducted at the Borden Chemicals and Plastics (BCP) acetylene plant site 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 sparger was used for nitrogen gas sparging into the vessel. The process was conducted in two-phase continuous and three-phase continuous modes. The naphthalene 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 naphthalene to the overhead gas space during the solvent sublation process was substantially less than that during conventional gas stripping. The improved performance of solvent sublation over both conventional gas stripping and solvent extraction operations was apparent.