Patent GB-1021281-A (GB)
Title: Fractionation process
IPC: C07C7/04
Filed: 1962-08-13
Abstract: Close boiling mixtures of hydrocarbons are separated into a first product fraction consisting of one of the compounds in pure form and a second product fraction in a plurality of fractionating columns by introducing the feed into an intermediate zone of one of the columns, passing at least part of at least one fraction obtained from each column to an intermediate zone of an adjacent column at least some of the final overhead being separated from one zone and at least some of the bottoms from another and the system being arranged so that for at least one of the columns from which the first product fraction is obtained the whole of the other fraction is passed to another column and no extraneous material is fed to any of the columns. In one embodiment feed is introduced into a first column from which overhead product is obtained, bottoms being passed to a second column from which overheads are returned to the first column and bottoms product is recovered; alternatively feed is introduced into the second column, and there may be intermediate columns from which both overheads and bottoms are passed to adjacent columns, products being recovered from the first and last columns.  In another embodiment feed passes to a second column from which overhead is passed to a first column which separates overhead product overhead and a bottoms returned to the second column while bottoms from the second passes to a third column which recovers bottoms product, overhead being returned to the second column.  The following separations are referred to:-(1) ethylbenzene from styrene; (2) ethylbenzene from xylenes; (3) o-xylene from m- and p-xylenes; (4) ethylene from ethane; (5) 2-methyl-2-pentene from cyclohexenes; (6) propylene from propane; (8) 2-methyl-1-butene and 2-methyl-2-butene from isoprene.ALSO:Close boiling mixtures of organic compounds, e.g cyclohexanone and cyclohexanol, are separated into a first product fraction consisting of one of the compounds in pure form and a second product fraction in a plurality of fractionating columns by introducing the feed into an intermediate zone of one of the columns, passing at least part of at least one fraction obtained from each column to an intermediate zone of an adjacent column at least some of the final overhead being separated from one zone and at least some of the bottoms from another and the system being arranged so that for at least one of the columns from which the first product fraction is obtained the whole of the other fraction is passed to another column and no extraneous material is fed to any of the columns.  In one embodiment feed is introduced into a first column from which overhead product is obtained, bottoms being passed to a second column from which overheads are returned to the first column and bottoms product is recovered; alternatively feed is introduced into the second column, and there may be intermediate columns from which both overheads and bottoms are passed to adjacent columns, products being recovered from the first and last.  In another embodiment feed passes to a second column from which overhead is passed to a first column which separates overhead product overhead and a bottoms returned to the second column while bottoms from the second passes to a third column which recovers bottoms product, overhead being returned to the second column.