METHOD FOR SELECTIVELY LOWERING CONTENT OF BENZENE AND LIGHT UNSATURATED COMPOUND IN HYDROCARBON FRACTION

摘要

PROBLEM TO BE SOLVED: To lower the content of harmful benzene and olefins in gasoline by positioning a hydrogenation zone for feedstock containing benzene as a specified unsaturated compound outside the distillation zone. ;SOLUTION: This method is one for treating a feedstock comprising 5 and 6C unsaturate compounds including benzene. A crude C5⁺ (i.e., 5C or higher) reformate is sent from a pipe 1 to a tower 2. The least volatile fraction of the reformate mainly consisting of 7C or higher hydrocarbons is recovered from the bottom of the tower from a pipe 5, boiled again in a heat exchanger 6 and is discharged from a pipe 7. The reboiled vapor is introduced again into the tower from a pipe 8. At the top of the tower, a light i.e., C5 or 6 or lower hydrocarbon vapor is sent to a condenser 10 through a pipe 9 and then sent to a tank 11 where it is separated into a liquid phase and a vapor phase. A liquid is withdrawn from a tray of the rectification zone of the tower, hydrogenated at 4a and 4b and sent to hydrogenation reactors 3a and 3b, and the effluent is recirculated into the tower through pipes 16a and 16b.;COPYRIGHT: (C)1997,JPO