Patent GB-899281-A (GB)
Title: Process for the extraction and recovery of aromatic hydrocarbons from a liquid hydrocarbon mixture
Inventor: ZUIDERWEG FREDERIK JOHANNES
IPC: C10G21/00
Filed: 1959-03-24
Abstract: Aromatic hydrocarbons are recovered from liquid hydrocarbon mixtures by extraction in a counterflow multistage extraction system at 140 DEG -155 DEG C. and under sufficient pressure to maintain the liquid phase with an aromatics-selective solvent boiling in the range 225 DEG -295 DEG C. and containing not more than 2% by weight of water; passing the extract at 140 DEG -155 DEG C. without appreciable flashing into a stripping zone operated at a lower pressure of at least 1,5 atmospheres absolute with a top temperature of 140 DEG -155 DEG C. and a bottom temperature of at least 190 DEG C.; condensing the overhead vapours and returning them, after removal of the aqueous phase, to the extraction; cooling the bottoms by at least 15 DEG C. to 170 DEG -180 DEG C. and distilling with direct steam at less than 0,5 atmospheres absolute and a bottom temperature of at least 150 DEG C. but at least 30 DEG C. lower than the bottom temperature of the stripping zone; and recycling the bottoms from the distillation, after cooling if necessary, to the extraction. The feed may be a catalytic reformate preferably not boiling above 220 DEG C.  The solvent may be a glycol or sulpholane used in a volume ratio to feed of 3-8:1.  The number of theoretical stages is preferably at least five, the feed being introduced at the first or second, as is the recycle from the stripping zone which amounts to a volume ratio to feed of 0,2-0,7:1.  The weight ratio of vaporous material in the extract entering the stripping zone to fresh feed to the system should be less than 1:10.  Specifications 739,200, 865,698, 888,147 and 899,280 are referred to.ALSO:Aromatic hydrocarbons are recovered from liquid hydrocarbon mixtures by extraction in a counterflow multistage extraction system at 140 DEG C.-155 DEG C. and under sufficient pressure to maintain the liquid phase with an aromatics-selective solvent boiling in the range 225 DEG C.-295 DEG C. and containing not more than 2% by weight of water; passing the extract at 140 DEG C.-155 DEG C. without appreciable flashing into a stripping zone operated at a lower pressure of at least 1.5 atmospheres absolute with a top temperature of 140 DEG C.-155 DEG C. and a bottom temperature of at least 190 DEG C.; condensing the overhead vapours and returning them, after removal of the aqueous phase, to the extraction; cooling the bottoms by at least 15 DEG C. to 170 DEG C.-180 DEG C. and distilling with direct steam at less than 0.5 atmospheres absolute and a bottom temperature of at least 150 DEG C. but at least 30 DEG C. lower than the bottom temperature of the stripping zone; and recycling the bottoms from the distillation, after cooling, if necessary, to the extraction.  The feed may be a catalytic reformate preferably not boiling above 220 DEG C.  The solvent may be a glycol or sulpholane used in a volume ratio to feed of 3-8 : 1.  The number of theoretical stages is preferably at least five, the feed being introduced at the first or second as is the recycle from the stripping zone which amounts to a volume ratio to feed of 0.2-0.7 : 1.  The amount of vaporous material in the extract entering the stripping zone should be less than that giving a weight ratio to fresh feed to the system of 1 : 10. Specifications 739,200, 865,698, 888,147 and 899,280 are referred to.