CA1150179A - Recovery of solvent in hydrocarbon extraction system - Google Patents
Recovery of solvent in hydrocarbon extraction systemInfo
- Publication number
- CA1150179A CA1150179A CA000369680A CA369680A CA1150179A CA 1150179 A CA1150179 A CA 1150179A CA 000369680 A CA000369680 A CA 000369680A CA 369680 A CA369680 A CA 369680A CA 1150179 A CA1150179 A CA 1150179A
- Authority
- CA
- Canada
- Prior art keywords
- solvent
- zone
- extract
- raffinate
- feedstock
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G21/00—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents
- C10G21/28—Recovery of used solvent
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G21/00—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G21/00—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents
- C10G21/06—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents characterised by the solvent used
- C10G21/12—Organic compounds only
- C10G21/18—Halogen-containing compounds
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
- C10G2400/10—Lubricating oil
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- Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
Abstract
Abstract:
A solvent refining process in which a hydrocarbon oil feed-stock to the process is first contacted with an inert gas used in the process for the recovery of solvent from at least one of the produce streams whereby the moisture con-tent of the feed stream and of the solvent in the system is maintained within the desired range and the solvent puri-fication is simplified with a resultant savings in energy required for the process.
A solvent refining process in which a hydrocarbon oil feed-stock to the process is first contacted with an inert gas used in the process for the recovery of solvent from at least one of the produce streams whereby the moisture con-tent of the feed stream and of the solvent in the system is maintained within the desired range and the solvent puri-fication is simplified with a resultant savings in energy required for the process.
Description
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Recovery of solvent in hydrocarbon extraction system _ .
The invention relates to an improved process for the solvent extraction of a petroleum oi~ fraction containing aromatic and non-aromatic componen~s. In one of its more specific aspects, the process relates to an improved method of recovering solvent from the hydrocarbon extract in a solvent extraction system. A considerable savings in the energy requirements of a solvent extraction process, as compared with processes employing conventional solvent recovery operations, is realized by the process of this invention.
The process of the invention effects the recovery of sol-vent from the extract phase in a plurality of separation steps comprising at least three pressure stages.
It is well known that aromatic and unsaturated components of a hydrocarbon oil charge stock may be separated from the more saturated hydrocarbon components by various pro-cesses involving solvent extraction of the aromatic and unsaturated hydrocarbons. Foremost among the processes which have received commercial acceptance are extraction with furfural, N-methyl-2-pyrrolidone and phenol. The removal of aromatics and other undesirable constituents from lubricating oil base stocks improves the viscosity index, color, oxidative stability, thermal stability, and inhibition response of the base oils and the ultimate lubri-cating oil products.
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A number of solvents are known which have an affinity for at least one component of a mixed oil charge stock and which are partially immiscible with an oil charge stock under t~e temperature and pressure conditions employed in S solvent refining the charge stock forming two liquid phases in the extraction zone, The two liquid phases gener-ally consist essentially of an extract phase containing the major amount of the solvent together with dissolved aromatic components of the charge stock and a raffinate phase con-lQ taining non~aromatic components o~ the charge stock togetherwith minor amounts of solvent, Among the solvents which are known to be useful for solvent extraction processing of petroleum base lubricating oil stocks are furfural, N-methyl-
Recovery of solvent in hydrocarbon extraction system _ .
The invention relates to an improved process for the solvent extraction of a petroleum oi~ fraction containing aromatic and non-aromatic componen~s. In one of its more specific aspects, the process relates to an improved method of recovering solvent from the hydrocarbon extract in a solvent extraction system. A considerable savings in the energy requirements of a solvent extraction process, as compared with processes employing conventional solvent recovery operations, is realized by the process of this invention.
The process of the invention effects the recovery of sol-vent from the extract phase in a plurality of separation steps comprising at least three pressure stages.
It is well known that aromatic and unsaturated components of a hydrocarbon oil charge stock may be separated from the more saturated hydrocarbon components by various pro-cesses involving solvent extraction of the aromatic and unsaturated hydrocarbons. Foremost among the processes which have received commercial acceptance are extraction with furfural, N-methyl-2-pyrrolidone and phenol. The removal of aromatics and other undesirable constituents from lubricating oil base stocks improves the viscosity index, color, oxidative stability, thermal stability, and inhibition response of the base oils and the ultimate lubri-cating oil products.
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A number of solvents are known which have an affinity for at least one component of a mixed oil charge stock and which are partially immiscible with an oil charge stock under t~e temperature and pressure conditions employed in S solvent refining the charge stock forming two liquid phases in the extraction zone, The two liquid phases gener-ally consist essentially of an extract phase containing the major amount of the solvent together with dissolved aromatic components of the charge stock and a raffinate phase con-lQ taining non~aromatic components o~ the charge stock togetherwith minor amounts of solvent, Among the solvents which are known to be useful for solvent extraction processing of petroleum base lubricating oil stocks are furfural, N-methyl-
2-pyrrolidone, phenols and other various well known organic and inorganic solvents.
Most recently N-methyl-2-pyrrolidone has displaced furfural and phenol in importance as preferred solvents for extract-ing aromatic hydrocarbons from mixtures of aromatic and non-aromatic hydrocarbons. The advantages of N-methyl-2-pyrrolidone as a lubricating oil extraction solvent for the removal of undesirabla aromatic and polar constituents from lubricating oil base stocks is now well recognized by re-finers, some of whom currently use or previously used other solvents, such as phenol or furfural for the refining of lubricating oil base stocks. N-methyl-2-pyrrolidone is generally the most preferred solvent because of its chemi~
cal stability, low toxicity, and its ability to produce refined oils of improved quality~
Typical of prior art solvent extraction processes illustrat-ing conventional solvent recovery operations are those dis-closed in U,S. 3,329,606; 3,461,066; 3,470,089; and 4,013,549.
The process of this invention is particularly adaptable to existing phenol, furfural and N-methyl-2~pyrrolidone refining ~S~7~
installations employing a single or multiple s~age solvent recovery system and steam or inert gas stripping of the solvent from the products. The invention is particularly suited to ~he conversion of furfural and phenol process installations to N methyl-2-pyrrolidone solvent systems with substantial savings in the energy requirements of the solvent refining processO
In recovering a hydrocarbon extraction solvent, e.g., N-methyl-2-pyrrolidone, from the oll-solvent mixtures, i.e., the extract phase and the raffinate phase, wherein said solvent is separated from said oil-solvent mixtures by a combination of distillation and stripping, stripping with an iner~ gas rat}ler than with steam simplifies solvent purification and reduces the energy requirements of the process, as compared with conventional steam stripping. Steam stripping is common in solvent refining processes. Inert gas stripping has been disclosed, for example, in U. S. 2,923,680; 4,013,549 and 4,057,491.
In conventional lubricating oil refining processes, the solvent extraction step is carried out under conditions effective to recover about 30 to 90 volume percent of the lubricating oil charge as raffinate or refined oil and to extract about 10 to 70 volume percent of the charge as an aromatic extract. The lubricating oil stock is contacted with a solvent, such as furfural or N-methyl-2-pyrrolidone, at a temperature at least 5C, preferably at least 50C, below the temperature of complete miscibility of said lubricating oil stock in said solvent.
Particularly preferred solvents are furfural and N-methyl-2-pyrrolidone, both of which are effective for the solvent extraction of aromatic components from lubricating oil charge stocks at relatively lower temperatures and lower solvent to oil dosages than most other known solvents.
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In the ex-trac-tion step, opera-ting conditions are selected to produce a primary raEfinate having a dewaxed viscosi-ty index of about 75 to 100, and ;l preferably about 85 to 96. When employing furfural as sol.ven-t, extraction temperatures within -the range of about 46 to 110 C (llS to 230F), and prefer-ably about 60 to 95 C (140 to 205 F), wi-th solvent dosages within the range of abou-t 100 -to 600 percent are employed in order to provide -the desired VI product.
When N-methyl-2-pyrrolidone is employed as solvent, solvent extraction tempera--tures wi-thin the range of 43 -to 100 C ~l.10 -to 212 F), preferably wi-thin -the range of 54 -to 95 C (130 -to 205 F), with solvent dosages wi-thin -the range of 50 to 500 percent, and preferably within the range of 100 to 300 percent, are suit-able. Water or wet solvent may be injected into -the bottom of the extractor or admixed wi-th the recycled solvent to control solvent power and selectivity.
To produce a finished lubricatiny oil base stock, -the primary raffinate is dewaxed -to the desired pour point. If desired, the refined or dewaxed oil may be subjected to a finishing treatment for colour and s-tability improvement, for example, mild hydrogenation.
The present i.nvention provides improvements in the methods of s-trip-ping solven-t from the ex-tract and raffinate products, eliminating oil contamin-ation in the solven-t, and controlling the water content of the solvent in the solvent refining system. The process of this invention simplifies solvent recovery and purification operations as compared with conventional processes and effects substantial savings in the energy requiremen-ts of a solvent refining process.
The present invention provides in a process for solvent refining a lubricating oil feedstock wherein said lubricating oil feedstock is contacted with a selec-tive solvent for aromatic constituents of said feedstock in an extraction zone thereby forming a raffinate phase comprising a minor amount of said solvent and an ex-tract phase comprising a major amount of said solvent, said rafEinate phase is separa-ted Erom said extract phase, said solvent is removed from each of said phases by :Elash vaporization, distillation, rectifi-cation or a combination thereof, and residual solvent is stripped from said extract and from said raffina-te with an inert s-tripping gas forming a mix-ture of solvent vapor and s-tripping gas, the improvement which comprises passiny said stripping gas containing solvent vapor into contact with fresh lubricating oil feedstock in a countercurren-t contacting zone prior -to the introduc-tion oE
said feeds-tock to said extraction zone whereby solven-t vapors are absorbed from said stripping gas by said feedstock and extraneous water contained in said feedstock is at least partially vaporized to form a mixture of iner-t gas and water vapor, and passing said mixture of inert gas and water vapor to a first condensing zone wherein a-t least a portion of said water vapor is condensed, separa-ting inert gas from condensed water, and passing inert ~as from which water and solvent have been removed into con-tact wi-th said extract and said raffina-te as said s-tripping gas for the removal of solvent therefrom.
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The accompanying drawing is a schematic flow diagram illus-trating a solvent refining process employing a modified sol-vent recovery operation in accordance with the process of this invention.
Lubricating oil feedstock, which may contain extraneous water, enters the system through line 5 and is heated in heater 6 to a temperature within the range of 65 to 120C
(about 150 to 250F). The preheated feedstock is intro-ducPd through line 7 into the upper part of an absorber-stripper column 8, suitably maintained at a pressure within the range of 100 to 415 kPa (0 to 60 psig), wherein the feedstock is stripped of water by an inert stripping gas entering the lower part of stripping column 8 through line 9.
Column 8 is provided with suitable means, for example, perforated, bubble cap or cascade trays, for insuring inti-mate countercurrent contact between the lubricating oil feedstock and the stripping gas. Inert gas containing water vapor is discharged from the top of column 8 through line 10. The resulting dehydrated feedstock is withdxawn fromthelower portion of column 8 and passed by pump 11 through heaker 12 and line 13 to the lower portion of extraction tower 14 where it is intimately countercurrently contacted with solvent entering the upper portion of ex-traction tower 14 through line 17. Wet solvent from sol-vent purification means 30 enters the bottom of extraction tower 14 via line 99.
The raffinate mixture, comprising typically 85 percent hydrocarbon oil admixed with solvent, i5 discharged from the extraction tower 14 through line 19 and processed for the recovery of raffinate from the solvent. The raffinate, after the separation of solvent, is the solvent refined lubricating oil base stock, i.e., the desired product of the process.
The major portion of the solvent appears in the extract 7~
mixture withdrawn from the bottom of extraction tower 14.
In this example, an extract mixture comprising about 85 percent solvent is withdraw~ from tower 14 through line 18.
The extract mixture is processed first for the recovery of solvent from the extract and then from recovery of the ex-tract as a marketable product of the process. The ma~ox portion of the extract mixture, typically containing about 85 percent of the solvent, is passed through heat exchangers 20 and 21 which serve to preheat the extract mixture, and introduced into a low pressure flash tower 22. Flash tower 22 typically operates at a pressure 170 to 205 kPa (10 to 15 psig). Extract mixture from ~ower 14 is introduced into the upper part of tower 22 as reflux through lines 31 and 32.
Solvent separated from the ex~ract in flash tower 22 is dis-charged through line 24 to heat exchanger 20 a~d, after con-densation of solvent vapors and further cooling in cooler 26, the solvent is passed through line 27 to solvent purifica-tion and storage 30 for reuse in the process.
The major portion of the extract mixture, from which part of the solvent has been removed, is withdrawn from the lower portion of column 22 by pump 36 and passed through heater 37 and line 38 to high pressure flash tower 39. The high pres-sure flash tower 39 suitably is operated at a pressure within the range of 375 to 415 kPa (40 to 45 psig). A minor por-tion of the extract mixture ~rom the bottom of extraction tower 14 is passed through lines 31 and 33 to the upper por-tion of high pressure separator 34 through lines 31 and 33 as r~flux for high pressure separator 34. Alternatively, solvent mixture from low pressure flash tower 22 may be supplied to tower 33 and tower 22 as reflux through lines 40, 31, 32 and 33.
The solvent vapors leaving the top of high pressure flash tower 39 through line 41 are passed through heat exchanger 21 in indirect heat exchange with the extract mixture from the bottom of extraction tower 14, condensing the solvent vapors and preheatlng the extract mixture prior to its S~l7'~
introduction to low pressure flash tower 22. Recovered solvent is passed through line 42 to a solvent accumulator purification and storage 30 for reuse in the process.
The hydrocarbon oil extract withdrawn from the bottorn of high pressure separator 39 through line 44 still contains some solvent, or example, 5 to 15 volume percent solvent and 9S to 85 volume percent hydrocarbons. This extrac~
mixture is passed through line 44 to vacuum flash tower 46 for the further recovery of solvent from the e~txact.
Vacuum flash tower 46 typically comprises coun~ercurrent vapor-liquid contact trays, suitably of the cascade or bubble-~ray type construction. A portion of the extract mixture from extraction tower 14 or low pressure fLash tower 2~ is supplied to the top of vacuum flash tower 46 as reflux through lines 36 and 47~ The vacuum flash tower may operate at a pressure within the range of 10 to 100 kPa.
In the ~acuum flash tower 46, additional separation of extract from solvent takæs place. Solvent vapors are with-drawn from the top of flash tower 46 through line 48 to a condenser 49 and solvent accumulator 50. Uncondensed gases withdrawn from accumulator 50 throu~h line 51 to a suitable vacuum source, not illustrated, may be discarded or recir-culated ~hrough line 86.
An extract rich fraction is withdrawn from the bottom offlash tower 46 through line 54 and introduced into the upper portion of stripper 55. Stripper 55 is typically a countercurrent vapor-liquid contact column provided with bubble trays in which the liquid extract flowing downwardly through the colu~l is contacted with inert stripping gas introduced into the lower portion of stripper 55 through line 56. A part of the extract mixture from the bottom of extraction tower 14 is supplled as reflux to the upper por-tion of stripper 55 through lines 36 and 57. Alternatively, a part of the extract mixture from the bottom of low pres-sure flash tower Z2 may be supplied as reflux to towers 22, 39, 46 and 55 via line 40.
Extract oil con~aining less than about 50 parts per million solvent, and typically comprising 80 percent unsaturated hydrocarbons and abou~ 20 percent saturated hydrocarbons, is withdrawn from the lower end of stripper 55 by pump 58 and passed through heat exchanger 59 where it is cooled by indirect heat exchange with the raffinate mixture taken ovarhead from extractor 14 and discharged from the system through line 60 as a product o the process~
Inert stripping gas and stripped solvent vapors are dis-charged from the upper part of stripper 55 through line 62 to condens~er 63 where solvent vapors are condensed, Sol-vent condensate is collected in condensate accumulator 64.
Inert gas separated from tha condensate is discharged into line 65 for recirculation to the process as described here-inafter.
Raffinate mixture ~aken overhead from extracti.on tower 14via line 19 is heated in heat exchanger S9 by indirect heat exchange with s~ripped extract from extract stripper 55 and then passed through heat exchanger 67 and heater 68 prior to introduction into vacuum flash tower 70 wherein solvent is separated from the raffinate mixture. A minor portion of the raffinate mixture from line 19 ~y-passes heat ex-changers 59 and 67 and heater 68 and is introduced into 3Q the upper portion of vacuum flash tower 70 through line 71 as reflux, A further portion of the raffinate mixture from line 19 by~passes heat exchangers 59 and 62 and heater 63 and is introduced into the upper portion of stripper 75 through line 72 as reflux.
Solvent vapors separated from the raffinate mixture in ~5~7-~
g 1ash tower 70 are withdrawn from the top of the tower to line 48 and passed, together with solvent vapors from flash tower 46, to condenser 49 wherein the solvent vapors are condensed. The condensate solvent is collected in conden-sate accumulator 50 and uncondensed gases are withdrawnthrough line 51, as explained hereinabove, Raffinate, still containing some solvent, is withdrawn from the lower part o~ vacuum flash tower 70 through line 74 to the upper part of stripping column 75 wherein the residual solvent is removed from the raffinate by stripping with inert gas enterin~ the lower part of stripper 75 through line 76. Raffinate, substantially free from solvent, is withdrawn as a product of the process from the lower por-tion of stripper 75 by pump 77, passed in indirect heatexchan~e with raffinate mixture from line 19 in heak ex-changer 67, and discharged through line 78 as the refined lubricating stock, the principal product of the process.
Condensates from accumulator drums 50 and 64 are passed by pumps 79 and 80, respectively, to solvent purification and storage system 30. Various process steps may be utiliæed in the purification of solvent for reuse in the process, including, for example, distillation, and azeotropic sepa-ration, absorption, gas stripping, and the like, primarilyfor removal of excess water, if present, and for removal of polymers, oils, and the like. Excess water from any extraneous source may be removed from the solvent purifi-cation and storage system 30 through line 81. Solvent is recycled to the process by pump 82 through line 83 to line 17, as required~
Inert gas from strippers 55 and 75, after separation of condensate solvent in condensate separator 64, may still contain sol~ent vapors The inert gas from separator 64 is repressured by compressor 85 and passed through line 86 ~L~5~7~3 to absorber-stripper 8 which serves as an absorber for sol-vent vapors remaining in the inert gas stream, The inert gas stream leaving compressor 85, suitably at a pressure in the range of 170 to 310 kPa (10 to 45 psig) or higher, depending upon the pressure in tower 8, is at an elevated temperature due to the heat of compression in the compressor.
This gas stream may be heated or cooled as required to main-tain the desired temperature in absorber-stripper tower 8 which is suitably at a temperature within the range of 65 to 150C ~about 150 to about 300FJo In the absorber-stripper 8, solvent vapors are absorbed from the inert gas, and water entering the system with the lube oil feedstream is vaporized into the inert gas~ Inert gas containing water vapor leaves the a~sorber-stripper column 8 through line 10 and is cooled in condenser 88 to a temperature sufficient to condense water vapor from the inert gas stream. Condensate separated from the inert gas is col-lected in condensate separator 8g from which condensate com~
prising water is discharged through line 90. Inert gas from which water and solvent ~apors have been removed is passed through line 91 and through heater 92 to lines 56 and 76 for introduction into strippers 55 and 75, respectively~
The stripping gas may comprise a substantially inert gas including, but not limited to, nitrogen, methane, carbon dioxide, and the like. Nitrogen is a preferred inert gas for use in the process.
30 By contacting fresh lubricating oil feedstock with inert stripping gas previously used in the process for stripping solvent from the extract and raffinate products, two impor-tant advantages are obtained. Solvent is recovered from the stripping gas and water is simultaneously removed from the feedstock, , . , . ~ ~ . . , , ,:
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In solvent refining of lubricatin~ oil stocks, there is a tendency for light oils to accumulate in the solvent. The accumulation of ligh~ oils in the solvent in the conven-tional solvent refining process requires additional dis~
tillation in the solvent purification process steps to remove the accumulated oils. These ligh~ oils usually are carried over from the extract and raffinate flash towers and strippers wi~h the solvent and stripping medium. In the process of this invention, a portion of the extract mixture from the extrac~ion tower 14 or from flash tower 2~ is employed as reflux to the flash towers 22 and 39 in the solvent recovery section of the process In the pre-ferred embodiment illustrated, extract mixture from the extraction tower 14 or from the low pressure flash tower column 22 is also utilized as reflux for the extract recov-ery columns, i.e., flash tower 46 and stripper 55. In this embodiment, the reflux to vacuum flash tower 65 and stripper 70 in the raffina~e recovery section o~ the process consists of a part of the raffinate mixture taken overhead from sol-vent extraction tower 14.
... The use of primary extract mixture from tower 14, or extract mixture from tower 22 from which a substantial portion of the solvent has been separated, as reflux to flash towers 22 and 39 substantially eliminates the carryover of lightoil from the towers with the separated solvent. Similarly, in the other towers, the relatively low volatilities of the extract fraction and of the raffinate fraction substantially reduces or eliminates the carryover of light hydrocarbons in the solvent vapors. At the same time, the raffinate and extract reflux streams are good absorbents for any light hydrocarbon oil vapors which might otherwise tend to be carried over from the various solvent separation towers.
The combination of pretreatment of fresh lubricating oil feedstock with the inert gas recycle and the reflux of the various towers with extract and raffinate effectively ~SC~ 9 _ 12 -eliminates or substa~ially reduces the amount of solvent purification required for the process.
In a specific example of the process of the present invention, 20,400 kg/hr (45,000 pounds per hour) of Wax distillate (WD-20) containing 45 ppm ~ater is fed to an absorber-stripper in accordance with the process o~ this invention where it is stxipped at llS~C and 138 kPa (20 psia) with 250 kg/hr (551 pounds per hour) o~ nitrogen recycle gas containing 12~7 kg/hr (28 pounds per hour) of N-methyl-2-pyrrolidone vapors carried over from the raffinate and extract strippers of a solvent refining unit as described hereinabove. In the absorber-stripper, the solvent contained in the recycled inert gas stream is recovered from the inert gas. At the same time, water contained in the lubricating oil charge stock is substan-tially completely vaporized into the nitrogen stripping gas.
The mixture of nitrogen and water vapor leaviny the absorber-stripper is cooled at 50C condensing the water vapor. Con-densate water is separated from the recycle gas stream and the resulting dry nitrogen heated to 290C and recirculated to the strippersi52~2 kg/hr (115 pounds per hour) of the heated dry nitrogen is supplied to the extract stripper and 197.7 kg/hr (436 pounds per hour) to the raffinate stripper.
The raffinate and extract strippers are operated at a bottom pressure of 35 kPa (5 psia) and an overhead pressure of 20.7 kPa (3 psia). Both strippers are refluxed with N-methyl-2-pyrrolidone at a temperature of 20C. The extract feed stream enters the extract stripper at 290C and the product extract leaves the stripper at 260C. The feed to the extract stripper contains 2,255 kg/hr (4,971 pounds per hour) of extract and 435 kg~hr (959 pounds per hour) N-methyl-2-pyrrolidone. 154.2 kg/hr (340 pounds pr hour) N-methyl-2-pyrrolidone is supplied to the extract stripper as reflux. Nitrogen stripping gas supplied to the stripper rlr'' at 290C and 35 kPa (S psia) at the rate of 52.2 kg/hr (115 pounds per hour) i~ disch~rged from the top of the stripper at 160C and 20.7 kPa (3 psia) together with 589.2 kg/hr (1,299 pounds per hour) of N~methyl-2-pyrroli-done. The overhead ~rom the extract stripper is combinedwith overhead from the raffinte stripper which comprises lg7.8 kg/hr (436 pounds per hour) nitrogen and 836 kg/hr (1,843 pounds per ho~r) N-methyl-2-pyrrolidone at 20.7 kPa (3 psia) and 155C. Nitrogen and N-methyl-2-pyrrolidone vapors from the strippers are passed to a condenser where they are cooled to 75C at 20.7 kPa (3 psia) condensing 1,425~2 kg/hr (3,142 pounds per hour) of solvent. After the removal of the condensate solvent, the nitrogen, amount-ing to 250 kg~hr (551 pounds per hour) and containing 12.7 kg/hr (28 pounds per hour) of solvent vapors at 75C, is passed to a compressor where the pressure of the mix-ture is rai~ed to 175 kPa (about 25 psia) with an increase in temperature to 120C. The compressed mixture i~
recycled to the absorber-stripper for recovery of the solvent vapors prior to reuse in the process.
Most recently N-methyl-2-pyrrolidone has displaced furfural and phenol in importance as preferred solvents for extract-ing aromatic hydrocarbons from mixtures of aromatic and non-aromatic hydrocarbons. The advantages of N-methyl-2-pyrrolidone as a lubricating oil extraction solvent for the removal of undesirabla aromatic and polar constituents from lubricating oil base stocks is now well recognized by re-finers, some of whom currently use or previously used other solvents, such as phenol or furfural for the refining of lubricating oil base stocks. N-methyl-2-pyrrolidone is generally the most preferred solvent because of its chemi~
cal stability, low toxicity, and its ability to produce refined oils of improved quality~
Typical of prior art solvent extraction processes illustrat-ing conventional solvent recovery operations are those dis-closed in U,S. 3,329,606; 3,461,066; 3,470,089; and 4,013,549.
The process of this invention is particularly adaptable to existing phenol, furfural and N-methyl-2~pyrrolidone refining ~S~7~
installations employing a single or multiple s~age solvent recovery system and steam or inert gas stripping of the solvent from the products. The invention is particularly suited to ~he conversion of furfural and phenol process installations to N methyl-2-pyrrolidone solvent systems with substantial savings in the energy requirements of the solvent refining processO
In recovering a hydrocarbon extraction solvent, e.g., N-methyl-2-pyrrolidone, from the oll-solvent mixtures, i.e., the extract phase and the raffinate phase, wherein said solvent is separated from said oil-solvent mixtures by a combination of distillation and stripping, stripping with an iner~ gas rat}ler than with steam simplifies solvent purification and reduces the energy requirements of the process, as compared with conventional steam stripping. Steam stripping is common in solvent refining processes. Inert gas stripping has been disclosed, for example, in U. S. 2,923,680; 4,013,549 and 4,057,491.
In conventional lubricating oil refining processes, the solvent extraction step is carried out under conditions effective to recover about 30 to 90 volume percent of the lubricating oil charge as raffinate or refined oil and to extract about 10 to 70 volume percent of the charge as an aromatic extract. The lubricating oil stock is contacted with a solvent, such as furfural or N-methyl-2-pyrrolidone, at a temperature at least 5C, preferably at least 50C, below the temperature of complete miscibility of said lubricating oil stock in said solvent.
Particularly preferred solvents are furfural and N-methyl-2-pyrrolidone, both of which are effective for the solvent extraction of aromatic components from lubricating oil charge stocks at relatively lower temperatures and lower solvent to oil dosages than most other known solvents.
, y~
In the ex-trac-tion step, opera-ting conditions are selected to produce a primary raEfinate having a dewaxed viscosi-ty index of about 75 to 100, and ;l preferably about 85 to 96. When employing furfural as sol.ven-t, extraction temperatures within -the range of about 46 to 110 C (llS to 230F), and prefer-ably about 60 to 95 C (140 to 205 F), wi-th solvent dosages within the range of abou-t 100 -to 600 percent are employed in order to provide -the desired VI product.
When N-methyl-2-pyrrolidone is employed as solvent, solvent extraction tempera--tures wi-thin the range of 43 -to 100 C ~l.10 -to 212 F), preferably wi-thin -the range of 54 -to 95 C (130 -to 205 F), with solvent dosages wi-thin -the range of 50 to 500 percent, and preferably within the range of 100 to 300 percent, are suit-able. Water or wet solvent may be injected into -the bottom of the extractor or admixed wi-th the recycled solvent to control solvent power and selectivity.
To produce a finished lubricatiny oil base stock, -the primary raffinate is dewaxed -to the desired pour point. If desired, the refined or dewaxed oil may be subjected to a finishing treatment for colour and s-tability improvement, for example, mild hydrogenation.
The present i.nvention provides improvements in the methods of s-trip-ping solven-t from the ex-tract and raffinate products, eliminating oil contamin-ation in the solven-t, and controlling the water content of the solvent in the solvent refining system. The process of this invention simplifies solvent recovery and purification operations as compared with conventional processes and effects substantial savings in the energy requiremen-ts of a solvent refining process.
The present invention provides in a process for solvent refining a lubricating oil feedstock wherein said lubricating oil feedstock is contacted with a selec-tive solvent for aromatic constituents of said feedstock in an extraction zone thereby forming a raffinate phase comprising a minor amount of said solvent and an ex-tract phase comprising a major amount of said solvent, said rafEinate phase is separa-ted Erom said extract phase, said solvent is removed from each of said phases by :Elash vaporization, distillation, rectifi-cation or a combination thereof, and residual solvent is stripped from said extract and from said raffina-te with an inert s-tripping gas forming a mix-ture of solvent vapor and s-tripping gas, the improvement which comprises passiny said stripping gas containing solvent vapor into contact with fresh lubricating oil feedstock in a countercurren-t contacting zone prior -to the introduc-tion oE
said feeds-tock to said extraction zone whereby solven-t vapors are absorbed from said stripping gas by said feedstock and extraneous water contained in said feedstock is at least partially vaporized to form a mixture of iner-t gas and water vapor, and passing said mixture of inert gas and water vapor to a first condensing zone wherein a-t least a portion of said water vapor is condensed, separa-ting inert gas from condensed water, and passing inert ~as from which water and solvent have been removed into con-tact wi-th said extract and said raffina-te as said s-tripping gas for the removal of solvent therefrom.
- 4a -, ~... ~
~ 3 ~ .
~L~LS~:9 7~
The accompanying drawing is a schematic flow diagram illus-trating a solvent refining process employing a modified sol-vent recovery operation in accordance with the process of this invention.
Lubricating oil feedstock, which may contain extraneous water, enters the system through line 5 and is heated in heater 6 to a temperature within the range of 65 to 120C
(about 150 to 250F). The preheated feedstock is intro-ducPd through line 7 into the upper part of an absorber-stripper column 8, suitably maintained at a pressure within the range of 100 to 415 kPa (0 to 60 psig), wherein the feedstock is stripped of water by an inert stripping gas entering the lower part of stripping column 8 through line 9.
Column 8 is provided with suitable means, for example, perforated, bubble cap or cascade trays, for insuring inti-mate countercurrent contact between the lubricating oil feedstock and the stripping gas. Inert gas containing water vapor is discharged from the top of column 8 through line 10. The resulting dehydrated feedstock is withdxawn fromthelower portion of column 8 and passed by pump 11 through heaker 12 and line 13 to the lower portion of extraction tower 14 where it is intimately countercurrently contacted with solvent entering the upper portion of ex-traction tower 14 through line 17. Wet solvent from sol-vent purification means 30 enters the bottom of extraction tower 14 via line 99.
The raffinate mixture, comprising typically 85 percent hydrocarbon oil admixed with solvent, i5 discharged from the extraction tower 14 through line 19 and processed for the recovery of raffinate from the solvent. The raffinate, after the separation of solvent, is the solvent refined lubricating oil base stock, i.e., the desired product of the process.
The major portion of the solvent appears in the extract 7~
mixture withdrawn from the bottom of extraction tower 14.
In this example, an extract mixture comprising about 85 percent solvent is withdraw~ from tower 14 through line 18.
The extract mixture is processed first for the recovery of solvent from the extract and then from recovery of the ex-tract as a marketable product of the process. The ma~ox portion of the extract mixture, typically containing about 85 percent of the solvent, is passed through heat exchangers 20 and 21 which serve to preheat the extract mixture, and introduced into a low pressure flash tower 22. Flash tower 22 typically operates at a pressure 170 to 205 kPa (10 to 15 psig). Extract mixture from ~ower 14 is introduced into the upper part of tower 22 as reflux through lines 31 and 32.
Solvent separated from the ex~ract in flash tower 22 is dis-charged through line 24 to heat exchanger 20 a~d, after con-densation of solvent vapors and further cooling in cooler 26, the solvent is passed through line 27 to solvent purifica-tion and storage 30 for reuse in the process.
The major portion of the extract mixture, from which part of the solvent has been removed, is withdrawn from the lower portion of column 22 by pump 36 and passed through heater 37 and line 38 to high pressure flash tower 39. The high pres-sure flash tower 39 suitably is operated at a pressure within the range of 375 to 415 kPa (40 to 45 psig). A minor por-tion of the extract mixture ~rom the bottom of extraction tower 14 is passed through lines 31 and 33 to the upper por-tion of high pressure separator 34 through lines 31 and 33 as r~flux for high pressure separator 34. Alternatively, solvent mixture from low pressure flash tower 22 may be supplied to tower 33 and tower 22 as reflux through lines 40, 31, 32 and 33.
The solvent vapors leaving the top of high pressure flash tower 39 through line 41 are passed through heat exchanger 21 in indirect heat exchange with the extract mixture from the bottom of extraction tower 14, condensing the solvent vapors and preheatlng the extract mixture prior to its S~l7'~
introduction to low pressure flash tower 22. Recovered solvent is passed through line 42 to a solvent accumulator purification and storage 30 for reuse in the process.
The hydrocarbon oil extract withdrawn from the bottorn of high pressure separator 39 through line 44 still contains some solvent, or example, 5 to 15 volume percent solvent and 9S to 85 volume percent hydrocarbons. This extrac~
mixture is passed through line 44 to vacuum flash tower 46 for the further recovery of solvent from the e~txact.
Vacuum flash tower 46 typically comprises coun~ercurrent vapor-liquid contact trays, suitably of the cascade or bubble-~ray type construction. A portion of the extract mixture from extraction tower 14 or low pressure fLash tower 2~ is supplied to the top of vacuum flash tower 46 as reflux through lines 36 and 47~ The vacuum flash tower may operate at a pressure within the range of 10 to 100 kPa.
In the ~acuum flash tower 46, additional separation of extract from solvent takæs place. Solvent vapors are with-drawn from the top of flash tower 46 through line 48 to a condenser 49 and solvent accumulator 50. Uncondensed gases withdrawn from accumulator 50 throu~h line 51 to a suitable vacuum source, not illustrated, may be discarded or recir-culated ~hrough line 86.
An extract rich fraction is withdrawn from the bottom offlash tower 46 through line 54 and introduced into the upper portion of stripper 55. Stripper 55 is typically a countercurrent vapor-liquid contact column provided with bubble trays in which the liquid extract flowing downwardly through the colu~l is contacted with inert stripping gas introduced into the lower portion of stripper 55 through line 56. A part of the extract mixture from the bottom of extraction tower 14 is supplled as reflux to the upper por-tion of stripper 55 through lines 36 and 57. Alternatively, a part of the extract mixture from the bottom of low pres-sure flash tower Z2 may be supplied as reflux to towers 22, 39, 46 and 55 via line 40.
Extract oil con~aining less than about 50 parts per million solvent, and typically comprising 80 percent unsaturated hydrocarbons and abou~ 20 percent saturated hydrocarbons, is withdrawn from the lower end of stripper 55 by pump 58 and passed through heat exchanger 59 where it is cooled by indirect heat exchange with the raffinate mixture taken ovarhead from extractor 14 and discharged from the system through line 60 as a product o the process~
Inert stripping gas and stripped solvent vapors are dis-charged from the upper part of stripper 55 through line 62 to condens~er 63 where solvent vapors are condensed, Sol-vent condensate is collected in condensate accumulator 64.
Inert gas separated from tha condensate is discharged into line 65 for recirculation to the process as described here-inafter.
Raffinate mixture ~aken overhead from extracti.on tower 14via line 19 is heated in heat exchanger S9 by indirect heat exchange with s~ripped extract from extract stripper 55 and then passed through heat exchanger 67 and heater 68 prior to introduction into vacuum flash tower 70 wherein solvent is separated from the raffinate mixture. A minor portion of the raffinate mixture from line 19 ~y-passes heat ex-changers 59 and 67 and heater 68 and is introduced into 3Q the upper portion of vacuum flash tower 70 through line 71 as reflux, A further portion of the raffinate mixture from line 19 by~passes heat exchangers 59 and 62 and heater 63 and is introduced into the upper portion of stripper 75 through line 72 as reflux.
Solvent vapors separated from the raffinate mixture in ~5~7-~
g 1ash tower 70 are withdrawn from the top of the tower to line 48 and passed, together with solvent vapors from flash tower 46, to condenser 49 wherein the solvent vapors are condensed. The condensate solvent is collected in conden-sate accumulator 50 and uncondensed gases are withdrawnthrough line 51, as explained hereinabove, Raffinate, still containing some solvent, is withdrawn from the lower part o~ vacuum flash tower 70 through line 74 to the upper part of stripping column 75 wherein the residual solvent is removed from the raffinate by stripping with inert gas enterin~ the lower part of stripper 75 through line 76. Raffinate, substantially free from solvent, is withdrawn as a product of the process from the lower por-tion of stripper 75 by pump 77, passed in indirect heatexchan~e with raffinate mixture from line 19 in heak ex-changer 67, and discharged through line 78 as the refined lubricating stock, the principal product of the process.
Condensates from accumulator drums 50 and 64 are passed by pumps 79 and 80, respectively, to solvent purification and storage system 30. Various process steps may be utiliæed in the purification of solvent for reuse in the process, including, for example, distillation, and azeotropic sepa-ration, absorption, gas stripping, and the like, primarilyfor removal of excess water, if present, and for removal of polymers, oils, and the like. Excess water from any extraneous source may be removed from the solvent purifi-cation and storage system 30 through line 81. Solvent is recycled to the process by pump 82 through line 83 to line 17, as required~
Inert gas from strippers 55 and 75, after separation of condensate solvent in condensate separator 64, may still contain sol~ent vapors The inert gas from separator 64 is repressured by compressor 85 and passed through line 86 ~L~5~7~3 to absorber-stripper 8 which serves as an absorber for sol-vent vapors remaining in the inert gas stream, The inert gas stream leaving compressor 85, suitably at a pressure in the range of 170 to 310 kPa (10 to 45 psig) or higher, depending upon the pressure in tower 8, is at an elevated temperature due to the heat of compression in the compressor.
This gas stream may be heated or cooled as required to main-tain the desired temperature in absorber-stripper tower 8 which is suitably at a temperature within the range of 65 to 150C ~about 150 to about 300FJo In the absorber-stripper 8, solvent vapors are absorbed from the inert gas, and water entering the system with the lube oil feedstream is vaporized into the inert gas~ Inert gas containing water vapor leaves the a~sorber-stripper column 8 through line 10 and is cooled in condenser 88 to a temperature sufficient to condense water vapor from the inert gas stream. Condensate separated from the inert gas is col-lected in condensate separator 8g from which condensate com~
prising water is discharged through line 90. Inert gas from which water and solvent ~apors have been removed is passed through line 91 and through heater 92 to lines 56 and 76 for introduction into strippers 55 and 75, respectively~
The stripping gas may comprise a substantially inert gas including, but not limited to, nitrogen, methane, carbon dioxide, and the like. Nitrogen is a preferred inert gas for use in the process.
30 By contacting fresh lubricating oil feedstock with inert stripping gas previously used in the process for stripping solvent from the extract and raffinate products, two impor-tant advantages are obtained. Solvent is recovered from the stripping gas and water is simultaneously removed from the feedstock, , . , . ~ ~ . . , , ,:
~ 15~D~7~
In solvent refining of lubricatin~ oil stocks, there is a tendency for light oils to accumulate in the solvent. The accumulation of ligh~ oils in the solvent in the conven-tional solvent refining process requires additional dis~
tillation in the solvent purification process steps to remove the accumulated oils. These ligh~ oils usually are carried over from the extract and raffinate flash towers and strippers wi~h the solvent and stripping medium. In the process of this invention, a portion of the extract mixture from the extrac~ion tower 14 or from flash tower 2~ is employed as reflux to the flash towers 22 and 39 in the solvent recovery section of the process In the pre-ferred embodiment illustrated, extract mixture from the extraction tower 14 or from the low pressure flash tower column 22 is also utilized as reflux for the extract recov-ery columns, i.e., flash tower 46 and stripper 55. In this embodiment, the reflux to vacuum flash tower 65 and stripper 70 in the raffina~e recovery section o~ the process consists of a part of the raffinate mixture taken overhead from sol-vent extraction tower 14.
... The use of primary extract mixture from tower 14, or extract mixture from tower 22 from which a substantial portion of the solvent has been separated, as reflux to flash towers 22 and 39 substantially eliminates the carryover of lightoil from the towers with the separated solvent. Similarly, in the other towers, the relatively low volatilities of the extract fraction and of the raffinate fraction substantially reduces or eliminates the carryover of light hydrocarbons in the solvent vapors. At the same time, the raffinate and extract reflux streams are good absorbents for any light hydrocarbon oil vapors which might otherwise tend to be carried over from the various solvent separation towers.
The combination of pretreatment of fresh lubricating oil feedstock with the inert gas recycle and the reflux of the various towers with extract and raffinate effectively ~SC~ 9 _ 12 -eliminates or substa~ially reduces the amount of solvent purification required for the process.
In a specific example of the process of the present invention, 20,400 kg/hr (45,000 pounds per hour) of Wax distillate (WD-20) containing 45 ppm ~ater is fed to an absorber-stripper in accordance with the process o~ this invention where it is stxipped at llS~C and 138 kPa (20 psia) with 250 kg/hr (551 pounds per hour) o~ nitrogen recycle gas containing 12~7 kg/hr (28 pounds per hour) of N-methyl-2-pyrrolidone vapors carried over from the raffinate and extract strippers of a solvent refining unit as described hereinabove. In the absorber-stripper, the solvent contained in the recycled inert gas stream is recovered from the inert gas. At the same time, water contained in the lubricating oil charge stock is substan-tially completely vaporized into the nitrogen stripping gas.
The mixture of nitrogen and water vapor leaviny the absorber-stripper is cooled at 50C condensing the water vapor. Con-densate water is separated from the recycle gas stream and the resulting dry nitrogen heated to 290C and recirculated to the strippersi52~2 kg/hr (115 pounds per hour) of the heated dry nitrogen is supplied to the extract stripper and 197.7 kg/hr (436 pounds per hour) to the raffinate stripper.
The raffinate and extract strippers are operated at a bottom pressure of 35 kPa (5 psia) and an overhead pressure of 20.7 kPa (3 psia). Both strippers are refluxed with N-methyl-2-pyrrolidone at a temperature of 20C. The extract feed stream enters the extract stripper at 290C and the product extract leaves the stripper at 260C. The feed to the extract stripper contains 2,255 kg/hr (4,971 pounds per hour) of extract and 435 kg~hr (959 pounds per hour) N-methyl-2-pyrrolidone. 154.2 kg/hr (340 pounds pr hour) N-methyl-2-pyrrolidone is supplied to the extract stripper as reflux. Nitrogen stripping gas supplied to the stripper rlr'' at 290C and 35 kPa (S psia) at the rate of 52.2 kg/hr (115 pounds per hour) i~ disch~rged from the top of the stripper at 160C and 20.7 kPa (3 psia) together with 589.2 kg/hr (1,299 pounds per hour) of N~methyl-2-pyrroli-done. The overhead ~rom the extract stripper is combinedwith overhead from the raffinte stripper which comprises lg7.8 kg/hr (436 pounds per hour) nitrogen and 836 kg/hr (1,843 pounds per ho~r) N-methyl-2-pyrrolidone at 20.7 kPa (3 psia) and 155C. Nitrogen and N-methyl-2-pyrrolidone vapors from the strippers are passed to a condenser where they are cooled to 75C at 20.7 kPa (3 psia) condensing 1,425~2 kg/hr (3,142 pounds per hour) of solvent. After the removal of the condensate solvent, the nitrogen, amount-ing to 250 kg~hr (551 pounds per hour) and containing 12.7 kg/hr (28 pounds per hour) of solvent vapors at 75C, is passed to a compressor where the pressure of the mix-ture is rai~ed to 175 kPa (about 25 psia) with an increase in temperature to 120C. The compressed mixture i~
recycled to the absorber-stripper for recovery of the solvent vapors prior to reuse in the process.
Claims (12)
1. In a process for solvent refining a lubricating oil feedstock wherein said lubricating oil feedstock is con-tacted with a selective solvent for aromatic constituents of said feed stock in an extraction zone thereby forming a raffinate phase comprising a minor amount of said solvent and an extract phase comprising a major amount of said solvent, said raffinate phase is separated from said ex-tract phase, said solvent is removed from each of said phases by flash vaporization, distillation, rectification or a combination thereof, and residual solvent is stripped from said extract and from said raffinate with an inert stripping gas forming a mixture of solvent vapor and stripping gas, the improvement which comprises passing said stripping gas containing solvent vapor into contact with fresh lubricating oil feedstock in a countercurrent contacting zone prior to the introduction of said feedstock to said extraction zone whereby solvent vapors are absorbed from said stripping gas by said feedstock and extraneous water contained in said feedstock is at least partially vaporized to form a mixture of inert gas and water vapor, and passing said mixture of inert gas and water vapor to a first condensing zone wherein at least a portion of said water vapor is condensed, separating inert gas from condensed water, and passing inert gas from which water and solvent have been removed into contact with said extract and said raffinate as said stripping gas for the removal of solvent therefrom.
2. A process according to Claim 1 wherein said solvent is N-methyl-2-pyrrolidone.
3. A process according to Claim 1 wherein said selective solvent is furfural.
4. A process according to Claim 1 wherein said selective solvent is phenol.
5. In a process for solvent refining a lubricating oil feedstock wherein said lubricating oil feedstock is con-tacted with a selective solvent for aromatic constituents of said feedstock in an extraction zone, the improvement comprising intimately contacting said feedstock with an inert gas stripping agent at a temperature in the range of about 150 to 300°F and at a pressure in the range of about 0 to 60 psig in a first contacting zone prior to said solvent extraction operation, separating said inert stripping gas from said feedstock, thereafter contacting said feedstock with solvent having preferential selectivity for the aromatic components of said feedstock in an ex-traction zone thereby forming a raffinate phase comprising a minor amount of said solvent and an extract phase com-prising a major amount of said solvent, separately with-drawing said raffinate and extract phases from said extraction zone, removing a portion of the solvent from said extract phase in an extract solvent separation zone, and thereafter removing a further portion of said solvent from said extract by contacting said extract in an extract stripping zone at a temperature of 400 to 700 F and pressure of 0 to 60 psig with said inert stripping gas from said first contacting zone thereby forming a mixture of stripp-ing gas and solvent vapor, and passing said inert gas con-taining solvent vapors from said extract stripping zone into contact with fresh lubricating oil feedstock in said first contacting zone effecting the recovery of solvent from said inert gas and simultaneously vaporizing water contained in said feedstock.
6. A process according to Claim 5 wherein said mixture of stripping gas and solvent vapors is cooled to a temperature in the range of from about 100 to 300°F at a pressure in the range of from about 15 to 60 psig effecting condensation of at least a part of said solvent vapors to a liquid, and condensed liquid solvent is separated from said inert gas prior to contact with said fresh feedstock.
7. In the process of Claim 5 wherein said feedstock con-tains water and said inert stripping gas separated from said feedstock in said first contacting zone contains water vapor, the additional step of passing said inert gas con-taining water vapor to a condensing zone wherein at least a part of said water vapor is condensed and separated from said inert gas prior to contacting said inert gas with said extract.
8. The process of Claim 5 comprising the additional steps of passing the major portion of said extract phase from said extraction zone to said extract solvent separation zone and passing a minor portion of said extract phase from the extraction zone to the upper part of said extract sol vent separation zone as reflux for said separation zone.
9. A process according to Claim 8 wherein a further minor portion of said extract from said extraction zone is intro-duced into the upper part of said extract stripping zone as a reflux therefor.
10. A process according to Claim 5 including the additional steps of removing a portion of the solvent from said raffi-nate phase in a raffinate solvent separation zone, there-after removing a further portion of said solvent from said raffinate by contacting said raffinate in a raffinate stripping zone with a portion of said inert gas from said first contacting zone forming a mixture of inert gas and solvent vapors and passing inert gas containing solvent vapors from said raffinate stripping zone to said first contacting zone.
11. A process according to Claim 10 wherein a minor por-tion of said raffinate phase from said extraction zone is supplied to the upper part of said raffinate solvent sepa-ration zone as reflux therefor.
12. A process according to Claim 11 wherein a further minor portion of said raffinate phase from said extraction zone is supplied to the upper part of said raffinate strip-
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US12157280A | 1980-02-14 | 1980-02-14 | |
| US121,572 | 1980-02-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1150179A true CA1150179A (en) | 1983-07-19 |
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ID=22397575
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000369680A Expired CA1150179A (en) | 1980-02-14 | 1981-01-29 | Recovery of solvent in hydrocarbon extraction system |
Country Status (18)
| Country | Link |
|---|---|
| JP (1) | JPS585957B2 (en) |
| KR (1) | KR840000578B1 (en) |
| AU (1) | AU6616381A (en) |
| BR (1) | BR8007934A (en) |
| CA (1) | CA1150179A (en) |
| DE (1) | DE3049204A1 (en) |
| EG (1) | EG15434A (en) |
| ES (1) | ES499438A0 (en) |
| FR (1) | FR2476117A1 (en) |
| GB (1) | GB2069525B (en) |
| GR (1) | GR73847B (en) |
| IT (1) | IT1141967B (en) |
| MA (1) | MA19063A1 (en) |
| NL (1) | NL8100515A (en) |
| PH (1) | PH17150A (en) |
| PT (1) | PT72462B (en) |
| YU (1) | YU28781A (en) |
| ZA (1) | ZA81221B (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2548912B1 (en) * | 1983-07-13 | 1985-12-13 | Moreno Gilbert | WORKOUT APPARATUS, ESPECIALLY FOR MOUNTAINEERERS |
| JPS60148444A (en) * | 1983-12-28 | 1985-08-05 | 日成通商株式会社 | Stringy body for packaging |
| KR101605053B1 (en) * | 2009-12-30 | 2016-03-21 | 아이알피씨 퍼블릭 컴퍼니 리미티드 | Methods and processes for producing process oils with a low polyaromatic hydrocarbon content |
| RU2532808C1 (en) * | 2013-08-20 | 2014-11-10 | Общество с ограниченной ответственностью "ВОКСТЭК" | Method of regenerating solvent in dewaxing and deoiling processes |
| CN103911172B (en) * | 2014-04-10 | 2016-06-29 | 辽宁石油化工大学 | A kind of method that ultrasonic assistant biodiesel solvent is refining |
| RU2651547C1 (en) * | 2017-06-05 | 2018-04-20 | Общество с ограниченной ответственностью "ВОКСТЭК" | Method of solvent regeneration during the dewaxing and decontamination processes |
| RU2688686C2 (en) * | 2017-08-21 | 2019-05-22 | Открытое акционерное общество "Славнефть-Ярославнефтеоргсинтез" (ОАО "Славнефть-ЯНОС") | Method for solvent regeneration in dewaxing and de-oiling processes |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2923680A (en) * | 1956-12-31 | 1960-02-02 | Exxon Research Engineering Co | Extraction process for refining lubricating oils |
| US4013549A (en) * | 1972-12-01 | 1977-03-22 | Exxon Research And Engineering Company | Lube extraction with NMP/phenol/water mixtures |
| US4057491A (en) * | 1976-03-26 | 1977-11-08 | Exxon Research & Engineering Co. | Solvent recovery process for N-methyl-2-pyrrolidone in hydrocarbon extraction |
-
1980
- 1980-09-02 PH PH24529A patent/PH17150A/en unknown
- 1980-10-09 JP JP55140684A patent/JPS585957B2/en not_active Expired
- 1980-12-04 BR BR8007934A patent/BR8007934A/en unknown
- 1980-12-27 DE DE19803049204 patent/DE3049204A1/en not_active Withdrawn
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1981
- 1981-01-05 GB GB8100118A patent/GB2069525B/en not_active Expired
- 1981-01-13 ZA ZA00810221A patent/ZA81221B/en unknown
- 1981-01-13 AU AU66163/81A patent/AU6616381A/en not_active Abandoned
- 1981-01-29 CA CA000369680A patent/CA1150179A/en not_active Expired
- 1981-02-03 YU YU00287/81A patent/YU28781A/en unknown
- 1981-02-03 NL NL8100515A patent/NL8100515A/en not_active Application Discontinuation
- 1981-02-05 PT PT72462A patent/PT72462B/en unknown
- 1981-02-09 MA MA19266A patent/MA19063A1/en unknown
- 1981-02-11 EG EG62/81A patent/EG15434A/en active
- 1981-02-12 IT IT19704/81A patent/IT1141967B/en active
- 1981-02-12 GR GR64111A patent/GR73847B/el unknown
- 1981-02-12 KR KR1019810000413A patent/KR840000578B1/en active
- 1981-02-13 ES ES499438A patent/ES499438A0/en active Granted
- 1981-02-13 FR FR8102884A patent/FR2476117A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| ES8202053A1 (en) | 1982-01-01 |
| IT8119704A0 (en) | 1981-02-12 |
| PT72462B (en) | 1982-02-04 |
| DE3049204A1 (en) | 1981-09-10 |
| PT72462A (en) | 1981-03-01 |
| NL8100515A (en) | 1981-09-16 |
| GR73847B (en) | 1984-05-07 |
| PH17150A (en) | 1984-06-13 |
| FR2476117B1 (en) | 1984-11-09 |
| IT1141967B (en) | 1986-10-08 |
| KR840000578B1 (en) | 1984-04-23 |
| JPS56116786A (en) | 1981-09-12 |
| GB2069525B (en) | 1984-02-15 |
| BR8007934A (en) | 1981-08-25 |
| FR2476117A1 (en) | 1981-08-21 |
| GB2069525A (en) | 1981-08-26 |
| YU28781A (en) | 1983-04-30 |
| EG15434A (en) | 1986-09-30 |
| ES499438A0 (en) | 1982-01-01 |
| ZA81221B (en) | 1982-05-26 |
| MA19063A1 (en) | 1981-10-01 |
| JPS585957B2 (en) | 1983-02-02 |
| KR830005335A (en) | 1983-08-13 |
| AU6616381A (en) | 1981-08-20 |
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