Two stage hydrocracking process and apparatus for multiple grade lube oil base feedstock production

摘要

Multiple grades of lube oil base feedstock are produced within a two-stage hydrocracking unit. Effluent from a first hydrocracking zone is sent to a separation zone, which includes multiple separation vessels, and a heavy liquid stream enters one cell of a dual cell fractionator charge heater and is flashed in the distillation zone of a divided wall fractionation column. A portion of the bottom stream from one side of the divided wall column is sent to the second hydrocracking zone. Feed to a second cell of the dual cell fractionation column is derived from the effluent of this second hydrocracking zone. A different lube oil base feedstocks is derived from each of the cells of the dual cell fractionation column.