GB2086412A - Method for the recovery of aromatic hydrocarbons - Google Patents
Method for the recovery of aromatic hydrocarbons Download PDFInfo
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- GB2086412A GB2086412A GB8034896A GB8034896A GB2086412A GB 2086412 A GB2086412 A GB 2086412A GB 8034896 A GB8034896 A GB 8034896A GB 8034896 A GB8034896 A GB 8034896A GB 2086412 A GB2086412 A GB 2086412A
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- 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
- C10G53/00—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes
- C10G53/02—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes plural serial stages only
- C10G53/04—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes plural serial stages only including at least one extraction step
- C10G53/06—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes plural serial stages only including at least one extraction step including only extraction steps, e.g. deasphalting by solvent treatment followed by extraction of aromatics
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/005—Processes comprising at least two steps in series
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/10—Purification; Separation; Use of additives by extraction, i.e. purification or separation of liquid hydrocarbons with the aid of liquids
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- 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
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- Organic Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- Water Supply & Treatment (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
A hydrocarbon mixture containing aromatic hydrocarbons such as cracked gasoline, catalytic reforming oils or crude benzene is extracted with a solvent which has a selectivity to the aromatic hydrocarbons first in a high temperature extraction zone 2, then in a low temperature extraction zone 10 and the extraction layer from the low temperature extraction zone is then subjected to an extractive distillation in which non-aromatic hydrocarbons are removed from the extraction layer, the aromatic hydrocarbons being recovered in a recovery zone 27. <IMAGE>
Description
SPECIFICATION
Method for the recovery of aromatic hydrocarbons
The present invention relates to a method of recovery of aromatic hydrocarbons by extracting them from a hydrocarbon mixture containing aromatic hydrocarbons with a solvent which has a high selectivity for aromatic hydrocarbons, and combining the extraction with extractive distillation and fractional distillation.
It is known to recover aromatic hydrocarbons from appropriate materials such as cracked gasoline, catalytic reforming oils, crude benzene (obtained from coal) with a solvent having a high selectivity for atomatic hydrocarbons such as sulfolane, diethylene glycol, dimethylsulfoxide,
N-methylpyrrolidone, N-formylmorpholine. This known extraction method is a liquid-liquid extraction method and has been used on an industrial scale (vide Japanese Patent Publication
No. 29,302/1977).An example of this method involves bringing into contact the starting hydrocarbon material with a solvent which can selectively dissolve aromatic hydrocarbons in an extraction zone to produce an extraction layer containing aromatic hydrocarbons and a remaining layer which contains non-aromatic hydrocarbons, and subjecting the extraction layer to extractive distillation in order to remove the contaminated non-aromatic hydrocarbons in an extractive distillation zone. Vapours exhausted from the top of the extractive distillation zone are liquified by cooling and are returned to the extractionszone and the liquid at the bottom of the extractive distillation zone is sent to a solventrecovering zone and therein is separated into aromatic hydrocarbons and solvent.It is known that extractive distillation for purifying aromatic hydrocarbons is usually carried out with the
introduction of an additional solvent.
However in order to separate the aromatic hydrocarbons in high purity and high yield, certain precautions are required. Specifically in order to increase the purity of the aromatic hydrocarbons an additional solvent is introduced into the
extractive distillation zone and the amount of vapor exhausted from the top of the extractive distillation zone should be large. On the other
hand, in order to increase the recovery rate of the
aromatic hydrocarbons, a large amount of solvent
should be used in the extraction zone and further
the temperature in the extraction zone should be
raised to increase the solvency power for the
aromatic hydrocarbons.As a result, due to the
increase in temperature in the extraction zone,
selectivity of the solvent is decreased, and due to
the increase of circulating solvent, responsibility at
the extractive distillation zone is increased, in other words, a large amount of heating energy is
required. Furthermore it has recently become
necessary to extract a wide range of aromatic
hydrocarbons simultaneously from light aromatic
hydrocarbons (e.g. benzene, toluene) to heavy
aromatic hydrocarbons (e.g. xylene, propylbenzene, trimethylbenzene, butylbenzene, tetramethylbenzene, naphthalene, or substances having a higher boiling point than these hydrocarbons).In this method, in order to obtain the aromatic hydrocarbons in high purity and high yield, it is required to increase the amount of circulating solvent and to increase the amount of vapor exhausted from top of the extractive distillation zone. Hence a large amount of heating energy is required.
As a result of the present inventors' intensive study, it has been found that aromatic hydrocarbons can be recovered in high purity and high yield with a decrease on the amount of circulating solvent and the amount of vapor exhausted from top of the extractive distillation zone by combining extraction at a high temperature and extraction at a low temperature with extractive distillation and fractional distillation.
The invention provides a method for the recovery of aromatic hydrocarbons from a hydrocarbon mixture which process comprises treating the mixture with a solvent which is selective towards aromatic hydrocarbons, at a temperature of from 40 to 2000C and a pressure sufficient to cause the extraction mixture to be in a liquid state to produce first and second layers, respectively relatively richer and poorer than each other in aromatic hydrocarbons, treating the first layer, at a temperature of from 20 to 1 C, which temperature is from 10 to 1 500C lower than the temperature at which the hydrocarbon mixture is treated with the selective solvent, and a pressure sufficient to cause the mixture to be in a liquid state with liquified gas obtained by condensing the vapor produced in an extractive distillation process, thereby to produce from the said first layer respective third and fourth layers, respectively, relatively richer and poorer than each other in aromatic hydrocarbons, performing the said extractive distillation process on the third layer to produce the said vapor, which is relatively rich in non-aromatic hydrocarbons, and a residue relatively rich in aromatic hydrocarbons, returning the fourth layer to the hydrocarbon mixture for treatment with further selective solvent, and recovering the aromatic hydrocarbons from the said aromatic hydrocarbon-rich residue.
In a particular embodiment, the invention provides a process for the recovery of aromatic hydrocarbons from a hydrocarbon mixture which comprises treating the mixture with a solvent which is selective towards the aromatic hydrocarbons in a zone maintained at a temperature of from 40 to 2000C and a pressure sufficient to maintain the mixture in a liquid state (hereinafter referred to as a high temperature extraction zone), to produce first and second layers, respectively relatively richer and poorer than each other in aromatic hydrocarbons, passing the first layer from the high temperature extraction zone to a zone maintained, at a temperature of from 20 to 1 900C, which temperature is from 10 to 1 500C lower than the temperature at which the hydrocarbon mixture is treated with the selective solvent, and a pressure sufficient to cause the mixture to be in a liquid state, hereinafter referred to as a low temperature extraction zone, in which the said first layer is extracted, to produce third and fourth layers respectively relatively richer and poorer than each other in aromatic hydrocarbons, passing the third layer from the low temperature extraction zone to an extractive distillation zone, in which non-aromatic hydrocarbons are removed, and then recovering the aromatic hydrocarbons in a recovery zone, the starting hydrocarbon mixture containing aromatic hydrocarbons being supplied to the middle part of the high temperature extraction zone, the selective solvent being supplied to the upper part of the high temperature extraction zone, and the said fourth layer from the low temperature extraction zone being supplied to the lower part of the high temperature extraction zone, the said first layer from the high temperature extraction zone being supplied to the upper part of the low temperature extraction zone being supplied to the upper part of the low temperature extraction zone, and a mixture obtained by liquifying gas mixture from the top of the extractive distillation zone being supplied to the lower part of the low temperature extraction zone.
Hereinafter from time to time the 2nd and 4th layers refers to the extraction remaining layer.
The present invention is illustrated with referring to the accompanying drawing.
Figure 1 is a flow diagram of one embodiment of the method of this present invention.
The extraction of aromatic hydrocarbons is carried out in a high temperature extraction zone (2) and in a low temperature extraction zone (10) and the extracted aromatic hydrocarbons are subjected to extractive distillation in an extractive distillation zone (18), followed by recovering in recovery zone (fractional distillation zone) (27).
The starting hydrocarbon mixture containing aromatic hydrocarbons is supplied to the middle part of the high temperature extraction zone (2) via a pipe (1) and a solvent having selectivity for aromatic hydrocarbons is supplied to the upper part of the high temperature extraction zone (2).
The extraction layer is taken out from the bottom of the high temperature extraction zone (2) and is supplied to the upper part of the low temperature extraction zone (10) via a pipe (3), a heat exchanger (4), a pipe (5), a mixer (8) and a pipe (9). While passing through the pipe (5), water and a solvent (e.g. sulfolane which may contain a small amount of hydrocarbons) may optionally be introduced via a pipe (6) and a pipe (7), respectively. The extraction layer which remains containing non-aromatic hydrocarbons is taken out from the top of the high temperature extraction zone via a pipe (30).
The extraction layer obtained in the low temperature zone (10) is taken out from the bottom of the low temperature zone (10) and is supplied to the upper part of the extractive distillation zone (18) via a pipe (17). The remaining layer in the low temperature extraction zone is taken out from the top of zone (10), and is returned to the lower part of the high temperature extraction zone (2) via a pipe (11), a pump (12), a pipe (13), a heat exchanger (15) and a pipe (16) and a part of the remaining layer is optionally circulated via the pipe (11), the pump (12), a pipe (14), the mixer (8) and the pipe (9).
The non-aromatic hydrocarbons contained in the extraction layer supplied from the low temperature extraction zone are separated in the extractive distillation zone (18) are taken out from the top of the zone (1 8). These hydrocarbons are then circulated via a pipe (19), a heat exchanger (20), a pipe (21), a liquid settling tank (22) and a pipe (32), during which they are liquified by cooling in the heat exchanger (20), and water is separated therefrom in the liquid settling tank (22) and is taken out via a pipe (23). A part of the hydrocarbons taken out from the extractive distillation zone is returned to the lower part of the low temperature extraction zone (10) via a pipe (24), during which light hydrocarbons may optionally be supplied via a pipe (25).Moreover, the internal refluxing mixture of hydrocarbons may be taken from a region above that which is being supplied an extraction layer from the low temperature extraction zone and is returned to the lower or middle part of the high temperature extraction zone (2) via a pipe (33).
The aromatic hydrocarbons obtained in the extractive distillation zone (18) are taken out from the bottom of the zone and are supplied to the middle part of the recovery zone (27) via a pipe (26). In the recovery zone (27), the aromatic hydrocarbons sent from the extractive distillation zone (18) are separated into pure aromatic hydrocarbons and the solvent, which is prompted by supplying steam via a pipe (31). The thus obtained aromatic hydrocarbons having a high purity are taken from the top of the recovery zone (27) via a pipe (28), and the solvent thus separated is returned to the upper part of the high temperature extraction zone (2) via a pipe (29).
In Figure 1, most of the ancillary equipment such as cooler, heater, valve pump, governor, or the like are omitted. Moreover, it will be apparent to persons skilled in the-art that the heat energy being present between various elements such as the high temperature extraction zone, the low temperature extraction zone, the extractive distillation zone, the recovery zone, or the like can readily be utilized by an appropriate means (e.g.
heat exchanger) from the viewpoint of saving energy.
The method of the present invention can be applied to various hydrocarbon mixtures having a narrow boiling point range or broad boiling point range, such as cracked gasoline, crude benzene obtained from coal, catalytic reforming gasoline, kerosine, or the like. These starting hydrocarbon mixtures may previously be subjected to pretreatments such as desulfurization, removal of oxygen or nitrogen, hydrogenation, or the like in order to meet the requirements for the final aromatic hydrocarbon products.
Possible solvents for use in the present invention include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, or propylene glycol; sulfolane or alkylsulfolanes having 1 to 3 carbon atoms in the alkyl moiety such as 2-methylsulfolane, 2,4-dimethylsulfolane, or 3-methylsulfolane; dimethylsulfoxide; N-methylpyrrolidone;
N-formylmorpholine; or the like.
These solvents may be used alone or in combination of two or more thereof and may optionally be used together with a small amount of water in order to improve the selectivity to aromatic hydrocarbons.
The method of the present invention can be carried out under conditions as used in the conventional extraction technique which is well known to persons skilled in the art. The most suitable conditions may vary with the kind of solvent used having different selectivity to aromatic hydrocarbons.
The detailed procedure of the present method is illustrated below in one embodiment using sulfolane as the solvent, but it is not limited thereto, and any person skilled in the art will easily be able to modify the conditions when using other solvents instead of sulfolane.
The liquid-liquid extraction of the present invention is carried out at two stages in the high temperature extraction zone and in the low temperature extraction zone. In these zones, conventional vessels such as a rotating disc contactor, a perforated plate column, a packed column, or the like can be used. The starting material containing the aromatic hydrocarbons is supplied to the middle part of the high temperature extraction zone. Sulfolane is supplied to the upper part of the high temperature extraction zone and is allowed to flow down into the zone, during which the aromatic hydrocarbons contained in the starting material dissolve in the sulfolane, and the resulting extraction layer is taken out from the bottom of the zone.The extraction in the high temperature extraction zone is carried out at a temperature of 40 to 2000C under a pressure of O to 28 kg/cm2G (under which pressure the mixture to be treated is kept in the liquid state), preferably at a temperature of 80 to 1 800C under a pressure of 3.5 to 10.5 kg/cm2G.
The sulfolane to be supplied to the upper part of the zone weights 2 to 10 times the weight of the starting hydrocarbon mixture. in order to improve the selectivity of sulfolane, 0.1 to 20% by weight, preferably 0.5 to 1.0% by weight, of water is added to the sulfolane. The extraction remaining layer taken out from the top of the high temperature extraction zone contains a small amount of sulfolane, and hence, the sulfolane may optionally be recovered by washing it with water in the usual manner.
The extraction layer taken out from the high temperature extraction zone is cooled and is supplied to the upper part of the low temperature extraction zone. The extraction in the low temperature zone is carried out at a temperature of 20 to 1 900C under a pressure of O to 28 Kg/cm2G (under which pressure the mixture to be treated is kept in the liquid state). In the low temperature extraction zone, the extraction is usually carried out at a temperature of 10 to 1 500C lower than the temperature in the high temperature zone. In order to improve the selectivity in this low temperature zone, water, sulfolane or sulfolane containing a small amount of hydrocarbons may be added to the extraction layer from the high temperature extraction zone.
Besides, this light paraffin or naphthene may be added to the solution to be supplied from the extractive distillation zone to the lower part of the low temperature extraction zone. The vapors of non-aromatic hydrocarbons and a part of aromatic hydrocarbons are taken out from the top of the extractive distillation zone and are liquified by cooling and then returned to the lower part of the low temperature extraction zone. The extraction remaining layer from the low temperature extraction zone is returned to the lower part of the high temperature extraction zone. The amount of the extraction remaining layer to be returned to the high temperature extraction zone is controlled so as to be at least 10% by weight of the total weight of the extraction layer obtained in the high temperature extraction zone.Besides, a part of the extraction remaining layer from the low temperature extraction zone may be added to the extraction layer from the high temperature extraction zone in order to promote the extraction effect at the low temperature extraction zone.
When the final aromatic hydrocarbon products are not required to have a high purity, the low temperature extraction zone may be done in a crude separation system using a single vessel, in which manner it is preferable to mix the liquified mixture of non-aromatic hydrocarbons and aromatic hydrocarbons taken out from the top of the low temperature extraction zone with the extraction layer from the high temperature extraction zone.
The extraction layer obtained in the low temperature extraction zone is sent to the upper part of the extractive distillation zone and therein is subjected to distillation in order to remove contaminated non-aromatic hydrocarbons and other impurities. The extractive distillation zone is controlled to such a pressure that the temperature at the bottom of the zone is not over the temperature at which the solvent decomposes. In case of using sulfolane, as the extracting medium, the temperature at the bottom of the zone is preferably lower than 2500C. The solution of aromatic hydrocarbons in a solvent is taken out from the bottom of the extractive distillation zone and is sent to the recovery zone.On the other hand, the gas mixture taken out from the top of the extractive distillation zone is liquified by cooling and then returned to the low temperature extraction zone, but a part thereof may be circulated to the top of the extractive distillation zone, and the internal refluxing mixture may optionally be taken out at the part upper than the part of supplying extraction layer from the low temperature extraction zone and returned to the lower or middle part of the high temperature extraction zone.
In the recovery zone, the solution of aromatic hydrocarbons in solvent is separated into pure aromatic hydrocarbons and solvent, and the aromatic hydrocarbons are recovered from the top of the recovery zone and the solvent is recovered from the bottom of the zone. The recovered solvent is returned to the high temperature extraction zone and optionally to the low temperature extraction zone (via a pipe (7)). In order to promote the separation into the aronnatic hydrocarbons and the solvent, the distillation at the recovery zone is usually carried out by steam distillation under reduced pressure.
The present invention is illustrated by the following Examples.
EXAMPLE 1
The starting mixture to be used was cracked gasoline having a boiling point of 80-1 500C and containing 70% by weight of aromatic hydrocarbons which was previously subjected to hydrogenation. The starting mixture was supplied to the high temperature extraction zone (2) via the pipe (1) at a rate of 100 parts by weight per hour.
In the high temperature extraction zone (2), a rotating disc contactor was used. The procedure at the high temperature extraction zone (2) was carried out at an extraction temperature of 800C and a pressure of 4 kg/cm2G using sulfolane as the extracting medium. The extracting medium was added to the upper part of the high temperature extraction zone (2) via the pipe (29) at a rate of 420 parts by weight per hour in the form of an extraction fraction (i.e. sulfolane: 414 parts by weight per hour, water: 4 parts by weight per hour, and aromatic hydrocarbons: 2 parts by weight per hour). The extraction remaining layer was taken out from the pipe (30) at a rate of 31.1 parts by weight per hour (i.e. nonaromatic hydrocarbons: 30 parts by weight per hour, aromatic hydrocarbons: 0.5 part by weight per hour, and sulfolane: 0.6 part by weight per hour).The extraction layer from the high temperature extraction zone (2) was taken out from the pipe (3) at a rate of 560.3 parts by weight per hour (i.e. aromatic hydrocarbons:
103 parts by weight per hour, sulfolane: 414.8 parts by weight per hour, non-aromatic hydrocarbons: 38.5 parts by weight per hour, and water: 4 parts by weight per hour). The extraction
layer was cooled by the heat exchanger (4) and was supplied to the low temperature extraction zone (10) via the pipe (5). As the low temperature extraction (10), a vertical phase separator was used.The procedure at the low temperature extraction zone (10) was carried out under a pressure of 3.8 kg/cm2G and at an extraction temperature of 300 C, the extraction remaining layer of the low temperature zone (10) was passed through the pipe (11), pressed by the pump (12), and a part thereof was heated by the heat exchanger (15) and was returned to the lower part of the high temperature extraction zone (2) via the pipe (16) at a rate of 71.4 parts by weight per hour (i.e. aromatic hydrocarbons: 31.5 parts by weight per hour, non-aromatic hydrocarbons: 38.5 parts by weight per hour, and sulfolane: 1.4 parts by weight per hour). Another part of the extraction remaining layer was passed through the pipe (14) at a rate of 142.8 parts by weight per hour (i.e.
aromatic hydrocarbons: 63 parts by weight per hour, non-aromatic hydrocarbons: 77 parts by weight per hour, and sulfolane: 2.8 parts by weight per hour) and was combined with the extraction layer from the high temperature extraction zone (2) and mixed in the mixer (8) and then returned to the low temperature extraction zone (10) via the pipe (9). (In this procedure, water and sulfolane which may contain a small amount of hydrocarbons may optionally be introduced via the pipe (6) and the pipe (7), respectively, but in this example, the introduction was omitted.) The extraction layer of the low temperature extraction zone (10) was supplied to the upper part of the extractive distillation zone (18) via the pipe (17) at a rate of 523.9 parts by weight per hour (i.e.
aromatic hydrocarbons: 83.5 parts by weight per hour, non-aromatic hydrocarbons: 23 parts by weight per hour, sulfolane: 41 3.4 parts by weight per hour, and water: 4 parts by weight per hour).
The procedure of the extractive distillation was carried out under a pressure of 0.1 kg/cm2G at the top of the zone and at a temperature of 840C at the top of the zone by using a multiple tray distillator. The vapor taken out from the top of the zone was passed through the pipe (19) and was liquified by cooling with the heat exchanger (20) and then entered into the liquid settling tank (22) via the pipe (21). Water separated in this liquid settling tank was drawn therefrom at a rate of 4 parts by weight per hour.Separated hydrocarbons were returned to the lower part of the low temperature extraction zone (10) via the
pipe (24) at a rate of 35 parts by weight per hour
(i.e. aromatic hydrocarbons: 12 parts by weight per hour, and non-aromatic hydrocarbons: 23 parts by weight per hour). (In this procedure, light hydrocarbons might be added via the pipe (25), but in this example, it was omitted.) The liquid stored at the bottom of the extractive distillation zone (18) was taken out and supplied to the recovery zone (27) via the pipe (26) at a rate of 484.9 parts by weight per hour (i.e.
aromatic hydrocarbons: 71.5 parts by weight per hour, and sulfolane: 413.4 parts by weight per hour). The procedure of the recovery zone was carried out under reduced pressure, i.e. under absolute pressure of 200 mmHg by using a multiple tray distillator. In order to improve the separability of aromatic hydrocarbons and sulfolane, steam was introduced into the lower part of the recovery zone (27) via the pipe (31).
From the top of the recovery zone (27), aromatic hydrocarbons was obtained at a rate of 69.5 parts by weight per hour (except water), and from the bottom thereof, the liquid was taken out and was circulated into the upper part of the high temperature extraction zone (2) via the pipe (29) at a rate of 420 parts by weight per hour.
EXAMPLE 2
The same starting material and apparatus as used in Example 1 were used.
The starting material was supplied to the high temperature extraction zone (2) via the pipe (1) at a rate of 100 parts by weight per hour. The procedure in the high temperature extraction zone (2) was carried out at an extraction temperature of 800C and a pressure of 4 kg/cm2G using sulfolane as the extracting medium. The extracting medium was added to the upper part of the high temperature extraction zone (2) via the pipe (29) at a rate of 420 parts by weight per hour in the form of an extraction fraction (i.e. sulfolane: 41 4 parts by weight per hour, water: 4 parts by weight per hour, and aromatic hydrocarbons: 2 parts by weight per hour).The extraction remaining layer was taken out from the pipe (30) art a rate of31.1 parts by weight per hour (i.e. non-aromatic hydrocarbons: 30 parts by weight per hour, aromatic hydrocarbons: 0.5 parts by weight per hour, and sulfolane: 0.6 part by weight per hour).
The extraction layer from the high temperature extraction zone (2) was taken out from the pipe (3) at a rate of 553.3 parts by weight per hour (i.e.
aromatic hydrocarbons: 100.6 parts by weight per hour, sulfolane: 414.8 parts by weight per hour, non-aromatic hydrocarbons: 33.9 parts by weight per hour, and water: 4 parts by weight per hour).
The extraction layer was cooled by the heat exchanger (4) and was supplied to the low temperature extraction zone (1 0) via the pipe (5).
The procedure at the low temperature extraction zone (10) was carried out under a pressure of 3.8 kg/cm2G and at an extraction temperature of 300 C. The extraction remaining layer of the low temperature extraction zone (10) was passed through the pipe (11), pressed by the pump (12), and a part thereof was heated by the heat exchanger (15) and was returned to the lower part of the high temperature extraction zone (2) via the pipe (16) at a rate of 64.4 parts by weight per hour (i.e. aromatic hydrocarbons: 29.1 parts by weight per hour, non-aromatic hydrocarbons: 33.9 parts by weight per hour, and sulfolane: 1.4 part by weight per hour).The extraction layer of the low temperature extraction zone (10) was supplied to the upper part of the extractive distillation zone (18) via the pipe (17) at a rate of 523.9 parts by weight per hour (i.e. aromatic hydrocarbons: 83.5 parts by weight per hour, nonaromatic hydrocarbons: 23 parts by weight per hour, sulfolane: 413.4 parts by weight per hour, and water: 4 parts by weight per hour). The procedure of the extractive distillation was carried out under a pressure of 0.1 kg/cm2G at the top of the zone and at a temperature of 840C at the top of the zone. The vapor taken out from the top of the zone was passed through the pipe (19) and was liquified by cooling with the heat exchanger (20) and then entered into the liquid settling tank (22) via the pipe (21). Water separated in this liquid settling tank was drawn therefrom at a rate of 4 parts by weight per hour.Separated hydrocarbons were returned to the lower part of the low temperature extraction zone (10) via the pipe (24) at a rate of 28 parts by weight per hour (i.e. aromatic hydrocarbons: 9.6 parts by weight per hour, and non-aromatic hydrocarbons: 1 8.4 parts by weight per hour). The remained hydrocarbons were refluxed at the top of the extractive distillation zone (18), and were returned to the lower part of the high temperature extraction zone (2) via the pipe (33) at a rate of 7 parts by weight per hour (i.e. aromatic hydrocarbons: 2.4 parts by weight per hour, nonaromatic hydrocarbons: 4.6 parts by weight per hour). The liquid stored at the bottom of the extractive distillation zone (18) was taken out and supplied to the recovery zone (27) via the pipe (26) at a rate of 484.9 parts by weight per hour (i.e. aromatic hydrocarbons: 71.5 parts by weight per hour, and sulfolane: 41 3.4 parts by weight per hour). From the top of the recovery zone (27), aromatic hydrocarbons was obtained at a rate of 69.5 parts by weight per hour (except water), and from the bottom thereof, the liquid was taken out and was circulated into the upper part of the high temperature extraction zone (2) via the pipe (29) at a rate of 420 parts by weight per hour.
Claims (14)
1. A method for the recovery of aromatic hydrocarbons from a hydrocarbon mixture which process comprises treating the mixture with a solvent which is selective towards aromatic hydrocarbons, at a temperature of from 40 to 2000C and a pressure sufficient to cause the extraction mixture to be in a liquid state, to produce first and second layers, respectively relatively richer and poorer than each other in aromatic hydrocarbons, treating the first layer, at a temperature of from 20 to 1900C, which temperature is from 10 to 1 500C lower than the temperature at which the hydrocarbon mixture is treated with the selective solvent, and a pressure sufficient to cause the mixture to be in a liquid state with liquified gas obtained by condensing the vapor produced in an extractive distillation process, thereby to produce from the said first layer respective third and fourth layers respectively relatively richer and poorer than each other in aromatic hydrocarbons, performing the said extractive distillation process on the third layer to produce the said vapor, which is relatively rich in non-aromatic hydrocarbons, and a residue relatively rich in aromatic hydrocarbons, returning the fourth layer to the hydrocarbon mixture for treatment with further selective solvent, and recovering the aromatic hydrocarbons from the said aromatic-hydrocarbon-rich residue.
2. A process for the recovery of aromatic hydrocarbons from a hydrocarbon mixture which comprises treating the mixture with a solvent which is selective towards the aromatic hydrocarbons in a zone maintained at a temperature of from 40 to 200"C and a pressure sufficient to maintain the mixture in a liquid state (hereinafter referred to as a high temperature extraction zone), to produce first and second layers, respectively relatively richer and poorer than each other in aromatic hydrocarbons, passing the first layer from the high temperature extraction zone to a zone maintained, at a temperature of from 20 to 1 900 C, which temperature is from 10 to 1 5O0C lower than the temperature at which the hydrocarbon mixture is treated with the selective solvent, and a pressure sufficient to cause the mixture to be in a liquid state, hereinafter referred to as a low temperature extraction zone, in which the said first layer is extracted to produce third and fourth layers, respectively relatively richer and poorer than each other in aromatic hydrocarbons, passing the third layer from the low temperature extraction zone to an extractive distillation zone, in which non-aromatic hydrocarbons are removed and then recovering the aromatic hydrocarbons in a recovery zone, the starting hydrocarbon mixture containing aromatic hydrocarbons being supplied to the middle part of the high temperature extraction zone, the selective solvent being supplied to the upper part of the high temperature extraction zone, and the said fourth layer from the low temperature extraction zone being supplied to the lower part of the high temperature extraction zone.
3. A method as claimed in claim 2, wherein a proportion of the internal refluxing mixture in the extractive distillation zone is removed at a point above that at which the said third layer from the low temperature extraction zone is introduced, and returned to the lower or middle part of the high temperature extraction zone.
4. A method as claimed in claim 2 and claim 3, wherein the solvent recovered in the recovery zone is circulated as the extracting medium to the high temperature extraction zone.
5. A method as claimed in any one of claims 2 to 4 wherein solvent recovered in the recovery zone is circulated as the extracting medium to the low temperature extraction zone.
6. A method as claimed in any one of claims 2 to 5 wherein a part of the said fourth layer from the low temperature extraction zone is combined with the said first layer from the high temperature extraction zone and is circulated into the low temperature extraction zone.
7. A method as claimed in any one of claims 2 to 6, wherein sulfolane is used as the solvent, the extraction in the high temperature extraction zone is carried out under a pressure of from 0 to 28 kg/cm2G and the extraction in the low temperature extraction zone is carried out under a pressure of from 0 to 28 kg/cm2G.
8. A method as claimed in claim 7, wherein the sulfolane includes from 0.1 to 20% by weight of water.
9. A method as claimed in claim 8, wherein the sulfolane includes from 0.5 to 10% by weight of water.
10. A method as claimed in any one of claims 6, 7 and 9 wherein water, sulfolane or sulfolane containing a small amount of hydrocarbons are added to the mixture in the low temperature zone.
11. A method as claimed in claims 7 to 10 wherein the sulfolane is used in an amount of 2 to 10 times by weight of the starting hydrocarbon mixture.
12. A method as claimed in any one of claims 2 to 10, wherein the extraction in the high temperature extraction zone is carried out at a temperature of 80 to 1 800C under a pressure of 3.5 to 10.5 kg/cm2G.
13. A method as claimed in any one of claims 2 to 12 wherein water is separated from the liquified gas mixture obtained from the extractive distillation zone before it is supplied to the low temperature extraction zone.
14. A method for the recovery of aromatic hydrocarbons substantially as hereinbefore described in any one of the foregoing specific examples.
1 5. A method for the recovery of aromatic hydrocarbons substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.
1 6. Aromatic hydrocarbons when produced by a process as claimed in any one of the preceeding claims.
1 7. In a method for the recovery of aromatic hydrocarbons from hydrocarbon mixture by extracting them with a solvent which has a selectivity to the aromatic hydrocarbons, the improvement comprising extracting aromatic hydrocarbons with a solvent in a high temperature extraction zone, sending the extraction layer from the high temperature extraction zone to a low temperature extraction zone, in which the extraction layer from the high temperature extraction zone is extracted, sending the extraction layer from the low temperature extraction zone to an extractive distillation zone, in which non-aromatic hydrocarbons are removed from the extraction layer, and then recovering the aromatic hydrocarbons in a recovery zone,
said extraction in the high temperature extraction zone being carried out under such a pressure that the extraction temperature is kept at the range of 40 to 2000C and the extraction mixture is in the liquid state, while supplying the starting hydrocarbon mixture containing aromatic hydrocarbons to the middle part of the high temperature extraction zone, supplying the solvent having a selectivity to aromatic hydrocarbons to the upper part of the high temperature extraction zone, and supplying an extraction remaining layer from the low temperature extraction zone to the lower part of the high temperature extraction zone, and
said extraction in the low temperature extraction zone being carried out at a temperature of 20 to 1 900C which is 10 to 1 500C lower than the temperature in the high temperature extraction zone and under such a pressure that the extraction mixture is kept in the liquid state, while supplying the extraction layer from the high temperature extraction zone to the upper part of the low temperature extraction zone and supplying the mixture obtained by liquifying the gas mixture exhausted from the top of the extractive distillation zone to the lower part of the low temperature extraction zone.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8034896A GB2086412B (en) | 1980-10-30 | 1980-10-30 | Method for the recovery of aromatic hydrocarbons |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8034896A GB2086412B (en) | 1980-10-30 | 1980-10-30 | Method for the recovery of aromatic hydrocarbons |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2086412A true GB2086412A (en) | 1982-05-12 |
| GB2086412B GB2086412B (en) | 1984-02-08 |
Family
ID=10516982
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8034896A Expired GB2086412B (en) | 1980-10-30 | 1980-10-30 | Method for the recovery of aromatic hydrocarbons |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2086412B (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9145521B2 (en) | 2011-07-29 | 2015-09-29 | Saudi Arabian Oil Company | Selective two-stage hydroprocessing system and method |
| US9144753B2 (en) | 2011-07-29 | 2015-09-29 | Saudi Arabian Oil Company | Selective series-flow hydroprocessing system and method |
| US9144752B2 (en) | 2011-07-29 | 2015-09-29 | Saudi Arabian Oil Company | Selective two-stage hydroprocessing system and method |
| US9359566B2 (en) | 2011-07-29 | 2016-06-07 | Saudi Arabian Oil Company | Selective single-stage hydroprocessing system and method |
| US9556388B2 (en) | 2011-07-29 | 2017-01-31 | Saudi Arabian Oil Company | Selective series-flow hydroprocessing system and method |
| WO2018220653A3 (en) * | 2017-06-02 | 2019-01-17 | Hindustan Petroleum Corporation Limited | Oil extract containing heat transfer fluid composition |
-
1980
- 1980-10-30 GB GB8034896A patent/GB2086412B/en not_active Expired
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9145521B2 (en) | 2011-07-29 | 2015-09-29 | Saudi Arabian Oil Company | Selective two-stage hydroprocessing system and method |
| US9144753B2 (en) | 2011-07-29 | 2015-09-29 | Saudi Arabian Oil Company | Selective series-flow hydroprocessing system and method |
| US9144752B2 (en) | 2011-07-29 | 2015-09-29 | Saudi Arabian Oil Company | Selective two-stage hydroprocessing system and method |
| US9359566B2 (en) | 2011-07-29 | 2016-06-07 | Saudi Arabian Oil Company | Selective single-stage hydroprocessing system and method |
| US9556388B2 (en) | 2011-07-29 | 2017-01-31 | Saudi Arabian Oil Company | Selective series-flow hydroprocessing system and method |
| WO2018220653A3 (en) * | 2017-06-02 | 2019-01-17 | Hindustan Petroleum Corporation Limited | Oil extract containing heat transfer fluid composition |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2086412B (en) | 1984-02-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |