Patent GB-626466-A (GB)
Title: Improvements in or relating to a process for the treatment of sulfuric acid extracts of olefinic hydrocarbons
Filed: 1946-05-22
Abstract: <PICT:0626466/III/1> In the treatment of sulphuric acid extracts of olefinic hydrocarbons foaming, during the subsequent steps for regenerating the olefins and recovering sulphuric acid therefrom, is prevented by treating the acid extract with cyclic hydrocarbons.  The cyclic hydrocarbon may be obtained by selective solvent extraction of petroleum oil, e.g. a distillate from a naphthenic base crude oil, and may be added, e.g. in amount from 1 pint to 20 gallons to 20,000 lbs. of acid extract, to the acid extract or the latter may be washed with a naphthene hydrocarbon or a naphthenic hydrocarbon oil, such as a lubricating oil distillate of 20-50 seconds Saybolt viscosity at 100 DEG  F., and in amount, for example, of 1-20 volume per cent of the acid extract, prior to the treatment for recovery of olefins and sulphuric acid therefrom. According to the drawing, a mixture of hydrocarbons containing olefins is pumped from a storage vessel 18 through a heat exchanger 22 (100 DEG  F.) into a first reactor 9 from the bottom of which liquid is withdrawn through line 25 and split into two streams, one portion passing to a settling drum 10 while the remainder is recycled to line 20, into which is discharged extract withdrawn from a second stage settling drum 12 via line 28. Unabsorbed or unreacted hydrocarbon vapours are discharged through line 29 into drum 10 from which unabsorbed hydrocarbons are passed through a heat exchanger (70 DEG  F.) into a second stage reactor 11, extract withdrawn therefrom being split into two streams, one portion passing via line 35 into settling drum 12 and the remainder being recirculated to line 30 into which regenerated sulphuric acid is admitted through line 37.  Unreacted hydrocarbon vapours from 11 pass into drum 12 and are withdrawn therefrom through outlet 39.  Acid extract from 10 is withdrawn through line 40 and washed with a naphthene hydrocarbon or naphthenic base oil which is admitted through line 19B, the mixture passing through a mixer 13 into a settling vessel 14 from which the upper two layers containing the naphthene hydrocarbon are withdrawn through line 19 and either recirculated with additional naphthene hydrocarbon added through 19B or withdrawn through 19A, while the lower or third layer containing sulphuric acid passes into a vent drum 15.  Instead of being washed, the extract from 10 may be passed through lines 40 and 4011 directly to vent drum 15 and the naphthene hydrocarbon extract be introduced through line 19C.  From 15 the acid extract is pumped to a regenerating tower 16 where hydrocarbon vapours are removed through line 45, scrubber 46 and cooler 49 into accumulator 50, gaseous products being vented at 51, while the condensate is removed through line 52, one portion being withdrawn through line 60 to join the liquid withdrawn from the bottom of 46 via line 59, another portion being returned to the scrubber 46, and another portion passing through line 55 is divided with one part discharging via line 56 into upper part of tower 16 while the remainder passes through a heater and line 57 into 16.  Acid is withdrawn from the bottom of 16 and passed to a concentrator 17, cooler 65 and returned via lines 37 and 34 to the reactor 11, make-up acid being introduced through line 68.ALSO:In the treatment of sulphuric acid extracts of olefinic hydrocarbons, foaming, during the subsequent steps for regenerating the olefins and recovering sulphuric acid therefrom, is prevented by treating the acid extract with <PICT:0626466/IV (b)/1> cyclic hydrocarbons.  The cyclic hydrocarbon may be obtained by selective solvent extraction of petroleum oil, e.g. a distillate from a naphthenic base crude oil, and may be added, e.g. in amount from 1 pint to 20 gallons to 20,000 pounds of acid extract, to the acid extract, or the latter may be washed with a naphthene hydrocarbon or a naphthenic hydrocarbon oil, such as a lubricating oil distillate of 20-50 seconds Saybolt viscosity at 100 DEG  F., and in amount, for example, of 1-20 volume per cent of the acid extract, prior to the treatment for recovery of olefins and sulphuric acid therefrom. According to the drawing, a mixture of hydrocarbons containing olefins is pumped from a storage vessel 18 through a heat-exchanger 22 (100 DEG  F.) into a first stage reactor 9 from the bottom of which liquid is withdrawn through line 25 and split into two streams, one portion passing to a settling drum 10 while the remainder is recycled to line 20 into which is discharged extract withdrawn from a second stage settling drum 12 via line 28.  Unabsorbed or unreacted hydrocarbon vapours are discharged through line 29 into drum 10 from which unabsorbed hydrocarbons are passed through a heat exchanger (70 DEG  F.) into a second stage reactor 11, extract withdrawn therefrom being split into two streams, one portion passing via line 35 into settling drum 12 and the remainder being recirculated to line 30 into which regenerated sulphuric acid is admitted through line 37. Unreacted hydrocarbon vapours from 11 pass into drum 12 and are withdrawn therefrom through outlet 39.  Acid extract from 10B withdrawn through line 40 and washed with a naphthene hydrocarbon or a naphthenic base oil which is admitted through line 19B, the mixture passing through a mixer 13 into a settling vessel 14 from which the upper two layers containing the naphthene hydrocarbon are withdrawn through line 19 and either recirculated with additional naphthene hydrocarbon added through 19B or withdrawn through 19A, while the lower or third layer containing sulphuric acid passes into a vent drum 15.  Instead of being washed, the extract from 10 may be passed through lines 40 and 4011 directly to vent drum 15 and the naphthene hydrocarbon extract be introduced through line 19C.  From 15 the acid extract is pumped to a regenerating tower 16 where hydrocarbon vapours are removed through line 45, scrubber 46 and cooler 49 into accummulator 50, gaseous products being vented at 51 while the condensate is removed through line 52, one portion being withdrawn through line 60 to join the liquid withdrawn from the bottom of 46 via line 59, another portion being returned to the scrubber 46, and another portion passing through line 55 is divided with one part discharging via line 56 into upper part of tower 16 while the remainder passes through a heater and line 57 into 16.  Acid is withdrawn from the bottom of 16 and passed into a concentrator 17, cooler 65 and returned via lines 37 and 34 to the reactor 11, make-up acid being introduced through line 68.