VAPOUR RECOVERY SYSTEM

摘要

Apparatus for recovering volatile organic compounds (VOC) from VOC/inert gas mixtures leaving tanker holds during crude oil loading comprises an absorption column (12) in which incoming VOC is absorbed into cold kerosene, a portion of the VOC rich kerosene leaving the absorption column being cooled in a cooler (88) and returned to the absorption column to contact incoming VOC/inert gas mixture and absorb further VOC. The remainder of the rich kerosene leaving the absorption column (12) passes to a buffer tank (34) where it is held. It is then pumped to an elevated pressure distillatin (stripper) column (46), where VOC is separated from the kerosene by conventional rectification. VOC vapour leaving the top of the distillation column is condensed in condenser (72) and held in the VOC reflux tank (76). Liquid VOC from the reflux tank is passed to a crude oil pipeline (82) or to a storage vessel; a portion of the liquid VOC from the reflux tank enters the top of the distillation column to act as reflux. Kerosene leaves the bottom of the distillation column (46) and passes to a storage tank (60) where it is held. From there, it passes through a cooler (66) to the absorption column, to absorb further VOC from incoming VOC/inert gas mixture. The coolers for this lean kerosene and for the rich kerosene which re-enters the absorption column are preferably cooled by the same refrigeration system (68). The buffer and storage tanks are of such a size that the elevated pressure distillation column can run continuously, supplied with VOC rich kerosene from the buffer tank and supplying VOC lean kerosene to the storage tank.