THREE PHASE EXTRACTIVE DISTILLATION WITH MULTIPLE COLUMNS CONNECTED IN SERIES

摘要

A novel method for connecting multiple existing columns which are retrofitted into vapor-liquid contacting devices with trays or packings suitable for the operation of a three-phase (vapor-liquid-liquid) extractive distillation column for aromatics recovery. The retrofitted columns are connected by a vapor transfer line to transfer the vapor phase from the top of the lower column to the bottom of the upper column, and by a liquid transfer line to transfer the liquid phase from the bottom of the upper column to the top of the lower column of the three-phase extractive distillation column. One improvement is the feeding of the ascending vapor from the top of the lower column to below the liquid level in the bottom of the upper column as the aeration/mixing driving force and/or in combination of the installation of a jet mixer to prevent phase separation, which is deemed to occur at the bottom of the upper column, wherein a bulk quantity of liquid is maintained without mixing in order to provide the hydraulic head for the bottom liquid transfer pump. The jet mixer, if installed, uses the bottom liquid from the upper column or the extractive solvent feed as the jetting liquid to provide the necessary mixing to homogenize and disperse the two liquid phases in the bottom of the upper column. Experimental data is disclosed for verifying the existence of two liquid phases in the three-phase extractive distillation column.