Patent GB-733726-A (GB)
Title: Improvements in or relating to light ends recovery from hydrocarbon fractions
IPC: C10G5/04
Filed: 1953-04-21
Abstract: Hydrocarbons boiling in the motor fuel boiling range are separated from a vaporous hydrocarbon mixture containing them together with appreciable quantities of hydrogen and lower boiling hydrocarbons by a process which comprises separating said vaporous hydrocarbon mixture in an initial separation zone 5 (see Figure) into a vaporous stream comprising said lower boiling hydrocarbons and hydrogen together with some of said hydrocarbons boiling in the motor fuel boiling range and a further stream comprising a condensed hydrocarbon stream substantially completely free of hydrogen, passing said condensed stream by line 7 to a stabilization zone 8 wherein a separation is made between higher-boiling hydrocarbons including those boiling in the motor fuel boiling range and lower boiling hydrocarbons, passing said higher boiling hydrocarbons via line 13 to a distillation zone 14 wherein a further separation is made between low boiling hydrocarbons and high boiling hydrocarbons, passing at least a portion of the said high boiling hydrocarbons from the distillation zone via lines 16 and 18 into the top of an absorption zone 17 as an absorption oil, removing overhead from stabilization zone 8 by line 9 lower boiling hydrocarbons, cooling the same and passing the cooled stream to a secondary separation zone 11, segregating uncondensed hydrocarbons and <PICT:0733726/IV (b)/1> passing them by line 20 to a lower point of the absorption zone, passing the aforesaid vaporous stream from the initial separation zone 5 by line 19 into an intermediate point of the absorption zone, countercurrently contacting the upflowing vaporous stream with the downflowing absorption oil whereby said hydrocarbons boiling in the motor fuel boiling range are absorbed in the absorption oil, removing hydrogen and hydrocarbon boiling below the motor fuel boiling range overhead from the absorption zone by line 21 and removing the absorption oil comprising said high boiling hydrocarbons and absorbed hydrocarbons boiling in the motor fuel boiling range from the bottom of the absorption zone and passing the same to the stabilization zone.  The process is particularly applicable to the segregation of hydrocarbon constituents from the mixture of product gases and hydrogen obtained from a hydroforming operation.  Thus, in the apparatus shown in the drawing, a hydrocarbon feed fraction, e.g. one p  boiling in the range of about 100 DEG  to 430 DEG  F., is introduced into hydroforming zone 2 which is operated at 850 DEG  to 950 DEG  F. and at 200 pounds per square inch gauge, using a hydroforming catalyst such as molybdenum on alumina carrier, the product gases containing a large volume of hydrogen being passed through cooling zone 4 before being introduced into the separation zone 5 for segregation as above.  A liquid product stream is withdrawn from the secondary separation zone 11 by means of line 12 and a low boiling hydroformate product is removed overhead from the distillation zone 14 through line 15.  A heavy hydroformate boiling in the range of 325 DEG  to 430 DEG  F. is removed from the distillation zone by line 16, at least a portion of this reformate being recycled to the top of the absorption zone while the remainder is withdrawn from the system.  An example is given to show that the amount of lean oil required for 71 per cent butane recovery is lower when carrying out the above procedure than it is when the gases from lines 19 and 20 are combined and introduced into the absorption zone.ALSO:<PICT:0733726/III/1> Hydrocarbons boiling in the motor fuel boiling range are separated from a vaporous hydrocarbon mixture containing then together with appreciable quantities of hydrogen and lower boiling hydrocarbons by a process which comprises separating said vaporous hydrocarbon mixture in an initial separation zone 4 (see Figure) into a vaporous stream comprising said lower boiling hydrocarbons and hydrogen together with some of said hydrocarbons boiling in the motor fuel boiling range and a further stream comprising a condensed hydrocarbon stream substantially completely free of hydrogen, passing said condensed stream via line 7 to a stabilization zone 8 wherein a separation is made between higher-boiling hydrocarbons including those boiling in the motor fuel boiling range and lower boiling hydrocarbons, passing said higher boiling hydrocarbons via line 13 to a distillation zone 14 wherein a further separation is made between low boiling hydrocarbons and high boiling hydrocarbons, passing at least a portion of the said high boiling hydrocarbons from the distillation zone via lines 16 and 18 into the top of an absorption zone 17 as an absorption oil, removing overhead from stabilization zone 8 by line 9 lower boiling hydrocarbons, cooling the same and passing the cooled stream to a secondary separation zone 11, segregating uncondensed hydrocarbons and passing them by line 20 to a lower point of the absorption zone, passing the aforesaid vaporous stream from the initial separation zone 5 via line 19 into an intermediate point of the absorption zone, countercurrently contacting the upflowing vaporous stream with the downflowing absorption oil whereby said hydrocarbons boiling in the motor fuel boiling range are absorbed in the absorption oil, removing hydrogen and hydrocarbons boiling below the motor fuel boiling range overhead from the absorption zone by line 21 and removing the absorption oil comprising said high boiling hydrocarbons and absorbed hydrocarbons boiling in the motor fuel boiling range from the bottom of the absorption zone and passing the same to the stabilization zone.  The process is particularly applicable to the segregation of hydrocarbon constituents from the mixture of product gases and hydrogen obtained from a hydroforming operation (see Group IV (b)). In this case the gaseous mixture from the hydroforming zone 2 is passed through cooling zone 4 prior to its introduction into the separation zone 5 for segregation as above.  A liquid product stream is withdrawn from the secondary zone 11 by means of line 12 and a low boiling hydroformate product is removed overhead from the distillation zone 14 by line 15.  A heavy hydroformate boiling in the range of 325 DEG  to 430 DEG  F. is removed from the distillation zone by line 16, at least a portion of this reformate being recycled to the top of the absorption zone while the remainder is withdrawn from the system.