Abstract: An interphase level regulator and method for using it are provided for continuously monitoring and controlling the level of tar in a settling or decanter tank where the tar is separated from an aqueous fluid. The interphase level regulator has an interphase tube vertically positioned inside or outside the settler or decanter tank after an initial separation of tar and aqueous fluid from the emulsion of tar and aqueous fluid. The interphase tube contains one or two pneumatic dip tubes that are supplied with air and yield a different pressure when a change occurs in the level of decanted tar in the interphase tube. The difference in pressure at the dip tube is measured and transmitted to a valve that controls the flow of decanted tar from the settler or decanter tank.

Abstract: A method for decreasing the naphthalene concentration in debenzolized light oil for greater naphthalene removal comprises pumping the primary light oil condensate and oil bled from a naphthalene scrubber or oil type final cooler to a level above the topmost additional tray in the top portion of a wash oil still.