CA1062644A - Separation process - Google Patents
Separation processInfo
- Publication number
- CA1062644A CA1062644A CA222,708A CA222708A CA1062644A CA 1062644 A CA1062644 A CA 1062644A CA 222708 A CA222708 A CA 222708A CA 1062644 A CA1062644 A CA 1062644A
- Authority
- CA
- Canada
- Prior art keywords
- zone
- oil
- liquid
- lean
- fractionation
- 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
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/11—Purification; Separation; Use of additives by absorption, i.e. purification or separation of gaseous hydrocarbons with the aid of liquids
-
- 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
- C10G7/00—Distillation of hydrocarbon oils
- C10G7/02—Stabilising gasoline by removing gases by fractioning
-
- 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
- C10G7/00—Distillation of hydrocarbon oils
- C10G7/08—Azeotropic or extractive distillation
Landscapes
- Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Water Supply & Treatment (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
- Extraction Or Liquid Replacement (AREA)
- Industrial Gases (AREA)
- Gas Separation By Absorption (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Process with improved efficacy for the separation and recovery of desired liquid and vapor constituents from a feed stream containing such constituents. The feed stream is contacted with two separate and distinct lean oils in an ab-sorption zone. Resultant rich oil passes to a stripping zone and then to a fractionation zones. A first lean oil is with-drawn from fractionation zone bottoms and enters the absorp-tion zone superior to the entry of a second lean oil. The second lean oil is withdrawn from the stripping zone and passed to the absorption zone. One preferred embodiment is found in the recovery of LPG and stabilized gasoline from liquid and vaporous products of a fluid catalytic cracking process.
Process with improved efficacy for the separation and recovery of desired liquid and vapor constituents from a feed stream containing such constituents. The feed stream is contacted with two separate and distinct lean oils in an ab-sorption zone. Resultant rich oil passes to a stripping zone and then to a fractionation zones. A first lean oil is with-drawn from fractionation zone bottoms and enters the absorp-tion zone superior to the entry of a second lean oil. The second lean oil is withdrawn from the stripping zone and passed to the absorption zone. One preferred embodiment is found in the recovery of LPG and stabilized gasoline from liquid and vaporous products of a fluid catalytic cracking process.
Description
The field of art to which this invention pertains is hydrocarbon processing. It particularly relates to the recovery of desired liquid and vaporous constituents from a hydrocarbonaceous liquid-vapor feed stream. Specifically, this invention relates to the recovery of LPG and stabilized gasoline in an improved separation process. ; -Hydrocarbons which are vaporous at normal condi- ;-; tions are employed in the synthesis of many organic com-pounds. Ethylene, for example, is in demand as a starting : ! lo material in the synthesis of alcohols and synthetic rubber.
~- Propylene and butylenes are in particularly great demand for plastics manufacture and for conversion to high octane :1 . . .
motor fuel blending components by polymerization and alkyl-' ation processes.
Sburces of these vaporous hydrocarbons are petro-j~ leum cracking and conversion processes such as thermal crack-; ~ ing, catalytic cracking, reforming, hydrocracking, etc. The l chemical reactions occurring in these processes produce com-.,~ , . ,;
mercially desirable quantities of vaporous hydrocarbons, ~20 and because of their utility it is desirable to recovex them.~ ~ .
in as high a concentration as possible. For this reason, separation processes are commonly used to concentrate and recover these hydrocarbons.
~;~ Separation processes currently in use are com-.
~; 25 prised of three major sections or zones: absorption, strip-ping and fractionation. In essencer these zones serve, re-- spectively, to absorb all but the lightest gaseous compo-~¦ ~ nents, strip dissolved gases from the absorbed components, ,",~: .,.
;i3l and fractionate the absorbed components into various product ,,,.1 .
:.i - 1 :., ~ -' . q~ .
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106;2644 streams. ~n outstanding feature of these processes is that usually the heavier components in the feed to the process are suitable for use as an absorber oil in the ab~oxption zone. A portion of the product stream containing these com-ponents is recycled back to the absorption zone. I have discovered an improvement which significantly improves the efficiency of such hydrocarbon separation processes.
It is an object of this invention to provide an improved method for the separation of hydrocarbons.
It is another object of this invention to provide a method for separating a liquid-vapor hydrocarbonaceous , mixture into normally vaporous products and normally liq-uid products in a more efficacious manner. In one embodi-ment, my invention affords an improvement in a process for the recovery of selected hydrocarbon liquid and vapor con-`, stituents from a feed stream containing those constituents wherein (i) the feed stream contacts a lean oil in an ab~
sorption zone; (ii) a rich oil from the absorption zone passes to a stripping zone; (iii) a stripped oil from the stripping zone passes to a fractionation zone; (iv) a por-tion of fractionation zone bottoms is returned to the ab-sorption zone as said lean oil, which improvement comprises returning individually to said absorption zone a portion of , ; said stripped oil and a portion of said fractionation zone bottoms as said lean oil.
The present invention involves a process for the recovery of normally vaporous and normally liquid hydro-... .
carbonaceous components from a composite stream containing :, .
these components, such as an effluent stream from a hydro-carbon conversion zone.
' -2-. : ~
106Z6~4 Lean oils absorb normally vaporous components from the composite stream in an absorption zone. Resulting rich oil passes to a stripping zone where light qases dis-solved in the rich oiL are removed and a stripped oil is S produced. A first portion of the stripped oil is returned to the absorption zone as a lower lean oil; the remaining portion of stripped oil passes to a fractionation zone.
The fractionation zone provides a liquefied hydrocarbon vapor product and a hydrocarbon liquid product. A portion of the hydrocarbon liquid product is returned to the ab-sorption zone as an upper lean oil. The provision and jux-taposition of the upper and lower lean oils improves re-covery of light feed components.
An embodiment of the present invention is illus-trated in the attached drawing. Only such details are in-r cluded as are necessary for a clear understanding of my in-vention, and no intention is thereby made to unduly limit its scope. Unnecessary items such as certain process streams, valves, pumps, instrumentation and other equipment have been :` :
omitted for the sake of simplicity.
Referring now to the separation process shown in the drawing, a feed stream comprising hydrogen, normally ~ vaporous hydrocarbons such as methane, ethane, propane, : etc., and normally liquid hydrocarbons such as pentane, hex-ane, etc. enters absorption zone 2 through conduit 1. A
first lean oil enters the top of absorption zone 2 in con-.. ~ :
duit 9. A second lean oil enters absorption zone 2 below the entry point of the first lean oil. These lean oils .. ~ :
I pass downwardly through absorption zone 2, absorbing at .' ;' ' ` ' '' .
. ~
. . , , . - , , , , ,. --.... ......... . .
106Z64~
least a portion of the vaporous hydrocarbon components of the feed. Gases not absorbed by the lean oil exit absorp-tion zone 2 in conduit 3. A rich oil stream, containing liquid feed components, lean oils and absorbed gaseou and vaporous feed components, exits absorption zone 2 in con-duit 4 and passes to stripping zone 5. Absorbed gases are removed from the rich oil in stripping zone 5 and pass in conduit 6 to conduit 1, intermixing therein with the feed.
Astripped oil stream is withdrawn from stripping zone 5 in conduit 7. A portion of stripped oil exits conduit 7 in conduit 8 and passes to absorption zone 2 as the afore-said second lean oil. The remaining portion of stripped oil exits conduit 7 in conduit 10 and passes to fractiona-tion zone 11 where this portion of stripped oil is separat-ed into a liquefied hydrocarbon vapor product and a hydro-carbon liquid. The liquefied hydrocarbon vapor product is withdrawn ~rom fractionation zone 11 and exits the process in conduit 14. The hydrocarbon liquid exits fractionation zone 11 in conduit 12. A portion of the hydrocarbon liquid : 20 exits conduit 12 in conduit 9, passing as aforesaid first lean oil to absorption zone 2. The remaining portion of the hydrocarbon liquid is withdrawn from conduit 12 in con-duit 13 and exits the process as a hydrocarbon liquid product.
~; The refining of petroleum involves numerous pro-cesses such as crude oil distillation, catalytic reforming of naphtha, catalytic cracking o~ residual oils, etc. These . processes are well known ~o those skilled in the art andneed not be discussed in great detail herein. However, a characteristic of these processes and many others to be . . -4-.
. .- ' '~
.
106Z644 b fouhd in petroleum refineries and hydrocarbon processing plants is the production of components which are broadly re-ferred to herein as "normally vaporous hydrocarbons" and ~ `
' "normally liquid hydrocarbons." Normally vaporous hydro-carbons are hydrocarbons which at "normal" conditions of , temperature and pressure exist in the vapor state. Condi-; tions referred to in the art as normal conditions are a pressùre of 1 atmosphere and a temperature of 60F. When ~, normally vaporous hydrocarbons are transformed from the vapor state to the liquid state, they are said to become liquefied hydrocarbon vapors. Normally liquid hydrocarbons are those which exist in the liquid state at normal condi- ~
-~ tions. The present invention broadly provides a method for ; ;
separating the effluent from any petroleum or hydrocarbon ~; 15 re~ining or conversion process which contains the types of Z components which are referred to as normally vaporous and normally liquid hydrocarbons.
~j~ ; For illustrative purposes, the present invention Z will be described with reference to the effluent from a fluid catalytic cracking process. Normally liquid and nor-mally vaporous hydrocarbons from a fluid catalytic cracking "
unit conventionally leave in the liquid and vapor streams from the fractionation zone of the unit. These streams are Z sent to a separation process for recovery of a stabilized liquid hydrocarbon product, or stabilized gasoline, lique- ;
fied hydrocarbon vapors and light gases. The stabilized -~
'~ ~ gasoliné product principally comprises hydrocarbons having ` 5 or more carbon atoms per molecule. This gasoline is re-ferred to as stabilized because it does not contain light l : `
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. .
106Z6~
material~ such as ethane or propane or hydrogen which would contribute effervescence to the gasoline. The liquefied hydrocarbon vapor from the separation process typically com-prises hydrocarbons having from 2 to 4 carbon atoms per molecule and includes such compounds as propane, butylenes and the like. Liquefied hydrocarbon vapor is commonly re-ferred to in the art as liquefied petroleum gas, or LPG.
This product may be further processed in downstream frac-tionation facilities if it is desired to produce further purified hydrocarbon product streams such as, for example, a stream substantially comprising hydrocarbons of only 3 carbon atoms. The light gas stream from the separation process commonly contains compounds such as methane and hydrogen. These liqht components are valuable primarily as fuel and are conducted from the separation process to a fuel system.
In the embodiment of the separation process of my invention shown in the attached drawing an admixture of normally liquid hydrocarbons and normally vaporous hydxo-carbons and hydrogen enters near the bottom of absorption ,' zone 2 through conduit 1. It should be noted that this is only one preferred embodiment. Another preferred embodiment would be to introduce the vaporous portion of the feed as shown and to introduce the liquid portion of the feed near the top of the absorption zone. The considerations involved here are: (a) the vaporous portion of the feed should tra-verse upwardly as many contact stages as possible within the absorption zone such that soluble components of the va-por are dissolved into liquid within the absorption zone to . ~ ' '.
: . .
: - , .
~0~;26qt4 the greatest extent possible; (b) if the liquid portion of the feed comes to the separation process substantially un-saturated in soluble vaporous components,then it should enter the absorption zone nearer the top in order to pass as many absorption stages as necessary to absorb as much as possible of these vaporous components. Therefore, this second preferred embodiment of points of introduction of the feed to the absorption zone can be desirable when the configuration of the upstream fluid catalytic cracking unit is such that liquid and vapor portions of the feed are de-livered to the separation process in separate conduits and when the liquid portion arrives at the separation process unsaturated in soluble vaporous feed components.
Absorption zone 2 may be one or more vertically disposed plate or packed absorption towers, having a total of 20 or more contact stages. The absorption zone is main-tained at conditions selected to absorb at least a portion ; Of the soluble vaporous components of the feed into the liquid within the absorption zone. These conditions include a pressure of from about 150 to 500 psig and a temperature of from about 80 to 150F. since absorption is normally exothermic, it may be necessary to provide one or more heat removal means to prevent the temperature within the absorp-tion zones from exceeding these limits. A preferred range of temperature of the effluent streams from absorption zone
~- Propylene and butylenes are in particularly great demand for plastics manufacture and for conversion to high octane :1 . . .
motor fuel blending components by polymerization and alkyl-' ation processes.
Sburces of these vaporous hydrocarbons are petro-j~ leum cracking and conversion processes such as thermal crack-; ~ ing, catalytic cracking, reforming, hydrocracking, etc. The l chemical reactions occurring in these processes produce com-.,~ , . ,;
mercially desirable quantities of vaporous hydrocarbons, ~20 and because of their utility it is desirable to recovex them.~ ~ .
in as high a concentration as possible. For this reason, separation processes are commonly used to concentrate and recover these hydrocarbons.
~;~ Separation processes currently in use are com-.
~; 25 prised of three major sections or zones: absorption, strip-ping and fractionation. In essencer these zones serve, re-- spectively, to absorb all but the lightest gaseous compo-~¦ ~ nents, strip dissolved gases from the absorbed components, ,",~: .,.
;i3l and fractionate the absorbed components into various product ,,,.1 .
:.i - 1 :., ~ -' . q~ .
;' ,: ~:
. ,.. , ........................... ~
106;2644 streams. ~n outstanding feature of these processes is that usually the heavier components in the feed to the process are suitable for use as an absorber oil in the ab~oxption zone. A portion of the product stream containing these com-ponents is recycled back to the absorption zone. I have discovered an improvement which significantly improves the efficiency of such hydrocarbon separation processes.
It is an object of this invention to provide an improved method for the separation of hydrocarbons.
It is another object of this invention to provide a method for separating a liquid-vapor hydrocarbonaceous , mixture into normally vaporous products and normally liq-uid products in a more efficacious manner. In one embodi-ment, my invention affords an improvement in a process for the recovery of selected hydrocarbon liquid and vapor con-`, stituents from a feed stream containing those constituents wherein (i) the feed stream contacts a lean oil in an ab~
sorption zone; (ii) a rich oil from the absorption zone passes to a stripping zone; (iii) a stripped oil from the stripping zone passes to a fractionation zone; (iv) a por-tion of fractionation zone bottoms is returned to the ab-sorption zone as said lean oil, which improvement comprises returning individually to said absorption zone a portion of , ; said stripped oil and a portion of said fractionation zone bottoms as said lean oil.
The present invention involves a process for the recovery of normally vaporous and normally liquid hydro-... .
carbonaceous components from a composite stream containing :, .
these components, such as an effluent stream from a hydro-carbon conversion zone.
' -2-. : ~
106Z6~4 Lean oils absorb normally vaporous components from the composite stream in an absorption zone. Resulting rich oil passes to a stripping zone where light qases dis-solved in the rich oiL are removed and a stripped oil is S produced. A first portion of the stripped oil is returned to the absorption zone as a lower lean oil; the remaining portion of stripped oil passes to a fractionation zone.
The fractionation zone provides a liquefied hydrocarbon vapor product and a hydrocarbon liquid product. A portion of the hydrocarbon liquid product is returned to the ab-sorption zone as an upper lean oil. The provision and jux-taposition of the upper and lower lean oils improves re-covery of light feed components.
An embodiment of the present invention is illus-trated in the attached drawing. Only such details are in-r cluded as are necessary for a clear understanding of my in-vention, and no intention is thereby made to unduly limit its scope. Unnecessary items such as certain process streams, valves, pumps, instrumentation and other equipment have been :` :
omitted for the sake of simplicity.
Referring now to the separation process shown in the drawing, a feed stream comprising hydrogen, normally ~ vaporous hydrocarbons such as methane, ethane, propane, : etc., and normally liquid hydrocarbons such as pentane, hex-ane, etc. enters absorption zone 2 through conduit 1. A
first lean oil enters the top of absorption zone 2 in con-.. ~ :
duit 9. A second lean oil enters absorption zone 2 below the entry point of the first lean oil. These lean oils .. ~ :
I pass downwardly through absorption zone 2, absorbing at .' ;' ' ` ' '' .
. ~
. . , , . - , , , , ,. --.... ......... . .
106Z64~
least a portion of the vaporous hydrocarbon components of the feed. Gases not absorbed by the lean oil exit absorp-tion zone 2 in conduit 3. A rich oil stream, containing liquid feed components, lean oils and absorbed gaseou and vaporous feed components, exits absorption zone 2 in con-duit 4 and passes to stripping zone 5. Absorbed gases are removed from the rich oil in stripping zone 5 and pass in conduit 6 to conduit 1, intermixing therein with the feed.
Astripped oil stream is withdrawn from stripping zone 5 in conduit 7. A portion of stripped oil exits conduit 7 in conduit 8 and passes to absorption zone 2 as the afore-said second lean oil. The remaining portion of stripped oil exits conduit 7 in conduit 10 and passes to fractiona-tion zone 11 where this portion of stripped oil is separat-ed into a liquefied hydrocarbon vapor product and a hydro-carbon liquid. The liquefied hydrocarbon vapor product is withdrawn ~rom fractionation zone 11 and exits the process in conduit 14. The hydrocarbon liquid exits fractionation zone 11 in conduit 12. A portion of the hydrocarbon liquid : 20 exits conduit 12 in conduit 9, passing as aforesaid first lean oil to absorption zone 2. The remaining portion of the hydrocarbon liquid is withdrawn from conduit 12 in con-duit 13 and exits the process as a hydrocarbon liquid product.
~; The refining of petroleum involves numerous pro-cesses such as crude oil distillation, catalytic reforming of naphtha, catalytic cracking o~ residual oils, etc. These . processes are well known ~o those skilled in the art andneed not be discussed in great detail herein. However, a characteristic of these processes and many others to be . . -4-.
. .- ' '~
.
106Z644 b fouhd in petroleum refineries and hydrocarbon processing plants is the production of components which are broadly re-ferred to herein as "normally vaporous hydrocarbons" and ~ `
' "normally liquid hydrocarbons." Normally vaporous hydro-carbons are hydrocarbons which at "normal" conditions of , temperature and pressure exist in the vapor state. Condi-; tions referred to in the art as normal conditions are a pressùre of 1 atmosphere and a temperature of 60F. When ~, normally vaporous hydrocarbons are transformed from the vapor state to the liquid state, they are said to become liquefied hydrocarbon vapors. Normally liquid hydrocarbons are those which exist in the liquid state at normal condi- ~
-~ tions. The present invention broadly provides a method for ; ;
separating the effluent from any petroleum or hydrocarbon ~; 15 re~ining or conversion process which contains the types of Z components which are referred to as normally vaporous and normally liquid hydrocarbons.
~j~ ; For illustrative purposes, the present invention Z will be described with reference to the effluent from a fluid catalytic cracking process. Normally liquid and nor-mally vaporous hydrocarbons from a fluid catalytic cracking "
unit conventionally leave in the liquid and vapor streams from the fractionation zone of the unit. These streams are Z sent to a separation process for recovery of a stabilized liquid hydrocarbon product, or stabilized gasoline, lique- ;
fied hydrocarbon vapors and light gases. The stabilized -~
'~ ~ gasoliné product principally comprises hydrocarbons having ` 5 or more carbon atoms per molecule. This gasoline is re-ferred to as stabilized because it does not contain light l : `
:
~ . --5 - i `
. ' ~
. .-:
. .
106Z6~
material~ such as ethane or propane or hydrogen which would contribute effervescence to the gasoline. The liquefied hydrocarbon vapor from the separation process typically com-prises hydrocarbons having from 2 to 4 carbon atoms per molecule and includes such compounds as propane, butylenes and the like. Liquefied hydrocarbon vapor is commonly re-ferred to in the art as liquefied petroleum gas, or LPG.
This product may be further processed in downstream frac-tionation facilities if it is desired to produce further purified hydrocarbon product streams such as, for example, a stream substantially comprising hydrocarbons of only 3 carbon atoms. The light gas stream from the separation process commonly contains compounds such as methane and hydrogen. These liqht components are valuable primarily as fuel and are conducted from the separation process to a fuel system.
In the embodiment of the separation process of my invention shown in the attached drawing an admixture of normally liquid hydrocarbons and normally vaporous hydxo-carbons and hydrogen enters near the bottom of absorption ,' zone 2 through conduit 1. It should be noted that this is only one preferred embodiment. Another preferred embodiment would be to introduce the vaporous portion of the feed as shown and to introduce the liquid portion of the feed near the top of the absorption zone. The considerations involved here are: (a) the vaporous portion of the feed should tra-verse upwardly as many contact stages as possible within the absorption zone such that soluble components of the va-por are dissolved into liquid within the absorption zone to . ~ ' '.
: . .
: - , .
~0~;26qt4 the greatest extent possible; (b) if the liquid portion of the feed comes to the separation process substantially un-saturated in soluble vaporous components,then it should enter the absorption zone nearer the top in order to pass as many absorption stages as necessary to absorb as much as possible of these vaporous components. Therefore, this second preferred embodiment of points of introduction of the feed to the absorption zone can be desirable when the configuration of the upstream fluid catalytic cracking unit is such that liquid and vapor portions of the feed are de-livered to the separation process in separate conduits and when the liquid portion arrives at the separation process unsaturated in soluble vaporous feed components.
Absorption zone 2 may be one or more vertically disposed plate or packed absorption towers, having a total of 20 or more contact stages. The absorption zone is main-tained at conditions selected to absorb at least a portion ; Of the soluble vaporous components of the feed into the liquid within the absorption zone. These conditions include a pressure of from about 150 to 500 psig and a temperature of from about 80 to 150F. since absorption is normally exothermic, it may be necessary to provide one or more heat removal means to prevent the temperature within the absorp-tion zones from exceeding these limits. A preferred range of temperature of the effluent streams from absorption zone
2 is 100 to 140F. Tbe heat removal means can be a system, such as those well known in the art, which removes liquid from an otherwise overheated stage within the absorption zone, pumps this liquid through a cooling device and re-. ~ .
.
~...... . ..
:: ~ . . .
~062644 turns the cooled liquid to the stage immediately below.
Liquid flowing downwa~d within the absorption zone, counter-current to upward-flowiny vapors, is provided by streams of lean oil which enter near the top of absorption zone 2 in conduits 8and 9. These streams are referred to as being lean because they are substantially less than saturated with vaporous feed components. In flowing downwardly through the absorption zone, the lean oils absorb vaporous feed com-ponents and a portion of gaseous feed components. Com-; 10 bined lean oils, absorbed vaporous feed components and liquid feed components exiting absorption zone 2 in conduit 4 are collectively referred to as rich oil. Gases which have not been absorbed by the lean oil are withdrawn from the top of absorption zone 2 in conduit 3. Rich oil with-drawn from absorption zone 2 in conduit 4 is introduced near the top of stripping zone 5.
As was indicated above, it is desired that the hydrogen and methane exit the separation process as gases ; in conduit 3 and that the ethane, propane, propylene, butanes : zo and butylenes exit the process as liquefied hydrocarbon va-por in conduit 14. Ideally, thereforer the rich oil enter-ing stripping zone 5 would contain no hydrogen or methane.
However, a portion of the hydrogen and methane in the feed -~is unavoidably absorbed in the rich oil, and the primary function of the stripping zone is to remove these absorbed ~; gases. Stripping zone 5 may be a conventional, vertically disposed plate or packed tower provided with heat input m~ans to furnish the heat for stripping. These heat input means may ke a conventional kettle reboiler or other such .~ .
1~6Z644 device. The stripping tower should preferably have 20 or more contact stages. Feed to the stripping tower prefer-ably enters at or near the top in order -that rich oil pro-vides liquid for rectification in all contact stages. Va-por generated through boiling of liquid in the heat input means flows upwardly in the stripping zone and counter-currently contacts the rich oil. The rectification which ensues enriches the vapor in the lighter components such that vapor withdrawn from stripping zone 5 in conduit 6, referred to as stripped vapors, contains substantially all ~, of the hydrogen and methane which entered stripping zone 5 with the rich oil. Because the stripped vapor also contains some heavier materials it is returned in conduit 6 to con~
, duit 1 and enters absorption zone 2 with the feed. In this manner the heavier materials which have unavoidably been stripped from the rich oil may be recovered, and the gaseous material in the stripped vapor may leave the absorption zone in conduit 3. Rich oil, after being stripped of absorbed gases in stripping zone 5, is referred to as stripped oil and exits stripping zone 5 in conduit 7. This stripped oil ' is suitable for use as lean oil and is divided into two , , fractions. One fraction of stripped oil exits conduit 7 in '' conduit 10 and passes to fractionation zone 11. The re~ , maining fraction of stripped oil exits conduit 7 in conduit ~, ~ 25 8 and passes as a lean oil to absorption zone 2.
Stripped oil entering fractionation zone 11 in ~' conduit 10 is fractionated into an overhead liquid material and a bottoms liquid material. The bottoms liquid material, - -~
which is suitable,for use as lean oil, exits fractionation , . . .
' ., .
,-. . .. : . : , . -1~626~4 zone 11 in conduit 12. A portion of bottoms liquid material exits conduit 12 in conduit 9, and passes to absorption zone 2. The portion of bottoms material remaining on con-duit 12 exits in ccnduit 13, leaving the process as a sta-bilized hydrocarbon liquid product. This product princi-pally comprises hydrocarbons having 5 or more carbon atoms.
Fractionation zone 11 may be a conventional, vertically oriented, plate or packed fractionation tower, having 25 or more contact stages, and furnished with overhead vapor con-~ 10 densing and reboiler heat input means. Fractionation zone ; feed preferably enters at or near the middle o the frac-tionation tower. The fractionation zone also has means for returning a portion of the overhead liquid material (con-densed overhead vapor) to the fractionation tower as reflux.
The remaining portion of overhead liquid material exits . , .
,! fractionation zone 11 in conduit 14 as a liquefied hydro-carbon vapor product. The liquefied hydrocarbon vapor pro-duct comprises hydrocarbons having 2 to 4 carbon atoms per ~; molecule.
... .
The separation zone of my invention is particùlar- -ly useful and novel by virtue of its manner of provlsion Of lean oil to the absorption zone. Stripped oil, while suit-able for use as lean oil, is not as effective as is frac-tionation zone bottoms material for absorption of the light-~, 25 est feed components. I have discovered that the recovery of light feed components can be maximized by a certain preset geometry of the upper section of ~he absorption zone. It is necessary that fractionation zone bottoms used as a lean oil enter the absorption zone above the top contact stage.
,~
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~06264~
It is also necessary that strlpped oil used as a lean oil enter the absorption zone below the entry of fractionation zone bottoms. In a preferred embodiment of my invention the two entry points of the lean oils should be separated by 5 to 10 of the absorption zone contact stages.
:: Reasonable variation and modification are possible within the scope of the foregoing d1sclosure, the drawing and the claims to the invention withou-t departing from the spirit thereofO
i ~' .' , ., ., ' .
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~062644 turns the cooled liquid to the stage immediately below.
Liquid flowing downwa~d within the absorption zone, counter-current to upward-flowiny vapors, is provided by streams of lean oil which enter near the top of absorption zone 2 in conduits 8and 9. These streams are referred to as being lean because they are substantially less than saturated with vaporous feed components. In flowing downwardly through the absorption zone, the lean oils absorb vaporous feed com-ponents and a portion of gaseous feed components. Com-; 10 bined lean oils, absorbed vaporous feed components and liquid feed components exiting absorption zone 2 in conduit 4 are collectively referred to as rich oil. Gases which have not been absorbed by the lean oil are withdrawn from the top of absorption zone 2 in conduit 3. Rich oil with-drawn from absorption zone 2 in conduit 4 is introduced near the top of stripping zone 5.
As was indicated above, it is desired that the hydrogen and methane exit the separation process as gases ; in conduit 3 and that the ethane, propane, propylene, butanes : zo and butylenes exit the process as liquefied hydrocarbon va-por in conduit 14. Ideally, thereforer the rich oil enter-ing stripping zone 5 would contain no hydrogen or methane.
However, a portion of the hydrogen and methane in the feed -~is unavoidably absorbed in the rich oil, and the primary function of the stripping zone is to remove these absorbed ~; gases. Stripping zone 5 may be a conventional, vertically disposed plate or packed tower provided with heat input m~ans to furnish the heat for stripping. These heat input means may ke a conventional kettle reboiler or other such .~ .
1~6Z644 device. The stripping tower should preferably have 20 or more contact stages. Feed to the stripping tower prefer-ably enters at or near the top in order -that rich oil pro-vides liquid for rectification in all contact stages. Va-por generated through boiling of liquid in the heat input means flows upwardly in the stripping zone and counter-currently contacts the rich oil. The rectification which ensues enriches the vapor in the lighter components such that vapor withdrawn from stripping zone 5 in conduit 6, referred to as stripped vapors, contains substantially all ~, of the hydrogen and methane which entered stripping zone 5 with the rich oil. Because the stripped vapor also contains some heavier materials it is returned in conduit 6 to con~
, duit 1 and enters absorption zone 2 with the feed. In this manner the heavier materials which have unavoidably been stripped from the rich oil may be recovered, and the gaseous material in the stripped vapor may leave the absorption zone in conduit 3. Rich oil, after being stripped of absorbed gases in stripping zone 5, is referred to as stripped oil and exits stripping zone 5 in conduit 7. This stripped oil ' is suitable for use as lean oil and is divided into two , , fractions. One fraction of stripped oil exits conduit 7 in '' conduit 10 and passes to fractionation zone 11. The re~ , maining fraction of stripped oil exits conduit 7 in conduit ~, ~ 25 8 and passes as a lean oil to absorption zone 2.
Stripped oil entering fractionation zone 11 in ~' conduit 10 is fractionated into an overhead liquid material and a bottoms liquid material. The bottoms liquid material, - -~
which is suitable,for use as lean oil, exits fractionation , . . .
' ., .
,-. . .. : . : , . -1~626~4 zone 11 in conduit 12. A portion of bottoms liquid material exits conduit 12 in conduit 9, and passes to absorption zone 2. The portion of bottoms material remaining on con-duit 12 exits in ccnduit 13, leaving the process as a sta-bilized hydrocarbon liquid product. This product princi-pally comprises hydrocarbons having 5 or more carbon atoms.
Fractionation zone 11 may be a conventional, vertically oriented, plate or packed fractionation tower, having 25 or more contact stages, and furnished with overhead vapor con-~ 10 densing and reboiler heat input means. Fractionation zone ; feed preferably enters at or near the middle o the frac-tionation tower. The fractionation zone also has means for returning a portion of the overhead liquid material (con-densed overhead vapor) to the fractionation tower as reflux.
The remaining portion of overhead liquid material exits . , .
,! fractionation zone 11 in conduit 14 as a liquefied hydro-carbon vapor product. The liquefied hydrocarbon vapor pro-duct comprises hydrocarbons having 2 to 4 carbon atoms per ~; molecule.
... .
The separation zone of my invention is particùlar- -ly useful and novel by virtue of its manner of provlsion Of lean oil to the absorption zone. Stripped oil, while suit-able for use as lean oil, is not as effective as is frac-tionation zone bottoms material for absorption of the light-~, 25 est feed components. I have discovered that the recovery of light feed components can be maximized by a certain preset geometry of the upper section of ~he absorption zone. It is necessary that fractionation zone bottoms used as a lean oil enter the absorption zone above the top contact stage.
,~
. , ' 1 0-- , .
:
:
~06264~
It is also necessary that strlpped oil used as a lean oil enter the absorption zone below the entry of fractionation zone bottoms. In a preferred embodiment of my invention the two entry points of the lean oils should be separated by 5 to 10 of the absorption zone contact stages.
:: Reasonable variation and modification are possible within the scope of the foregoing d1sclosure, the drawing and the claims to the invention withou-t departing from the spirit thereofO
i ~' .' , ., ., ' .
... .
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Claims (7)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a process for the recovery of selected hydrocarbon liquid and vapor constituents from a feed stream containing those constituents wherein:
(i) the feed stream contacts a lean oil in an absorp-tion zone;
(ii) a rich oil from the absorption zone passes to a stripping zone;
(iii) a stripped oil from the stripping zone passes to a fractionation zone; and, (iv) a portion of fractionation zone bottoms is returned to the absorption zone as said lean oil; the improvement which comprises returning individually to said absorption zone a portion of said stripped oil and a portion of said fractionation zone bottoms as said lean oil.
(i) the feed stream contacts a lean oil in an absorp-tion zone;
(ii) a rich oil from the absorption zone passes to a stripping zone;
(iii) a stripped oil from the stripping zone passes to a fractionation zone; and, (iv) a portion of fractionation zone bottoms is returned to the absorption zone as said lean oil; the improvement which comprises returning individually to said absorption zone a portion of said stripped oil and a portion of said fractionation zone bottoms as said lean oil.
2. Improved process of Claim 1 wherein the portion of fractionation zone bottoms enter said absorption zone above the entry of said portion of stripped oil.
3. Improved process of Claim 1 wherein the mole ratio of said portion of stripped oil to said portion of fractionation zone bottoms is in the range of about 1:1 to 10:1.
4. Improved process of any of Claims 1 to 3 wherein the stripped oil principally comprises hydrocarbon molecules having 2 or more carbon atoms.
5. Improved process of any of Claims 1 to 3 wherein the fractionation zone bottoms principally comprises hydrocarbon molecules having 5 or more carbon atoms.
6. Improved process of any of Claims 1 to 3 wherein the fractionation zone bottoms principally comprises hydrocarbons having 6 or more carbon atoms per molecule.
7. Improved process of any of Claims 1 to 3 wherein the feed stream comprises normally liquid and normally vaporous hydrocarbons and hydrogen.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US45365674A | 1974-03-21 | 1974-03-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1062644A true CA1062644A (en) | 1979-09-18 |
Family
ID=23801510
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA222,708A Expired CA1062644A (en) | 1974-03-21 | 1975-03-20 | Separation process |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5754162B2 (en) |
| CA (1) | CA1062644A (en) |
| DE (1) | DE2511968B2 (en) |
| FR (1) | FR2264795B1 (en) |
| GB (1) | GB1493075A (en) |
| IT (1) | IT1032394B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61162069A (en) * | 1985-01-11 | 1986-07-22 | Ricoh Co Ltd | Developing device |
| JPS6270882A (en) * | 1985-09-24 | 1987-04-01 | Canon Inc | Developer feeder |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2596785A (en) * | 1946-07-08 | 1952-05-13 | Pritchard & Co J F | Method of enriching natural gas |
| NL68945C (en) * | 1946-11-04 | |||
| US3574089A (en) * | 1969-01-27 | 1971-04-06 | Universal Oil Prod Co | Gas separation from hydrogen containing hydrocarbon effluent |
-
1975
- 1975-03-19 DE DE19752511968 patent/DE2511968B2/en not_active Withdrawn
- 1975-03-20 FR FR7508684A patent/FR2264795B1/fr not_active Expired
- 1975-03-20 GB GB1161075A patent/GB1493075A/en not_active Expired
- 1975-03-20 CA CA222,708A patent/CA1062644A/en not_active Expired
- 1975-03-20 JP JP50034210A patent/JPS5754162B2/ja not_active Expired
- 1975-03-20 IT IT4870675A patent/IT1032394B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| JPS50140372A (en) | 1975-11-11 |
| IT1032394B (en) | 1979-05-30 |
| GB1493075A (en) | 1977-11-23 |
| FR2264795B1 (en) | 1980-03-28 |
| DE2511968B2 (en) | 1980-08-07 |
| JPS5754162B2 (en) | 1982-11-17 |
| FR2264795A1 (en) | 1975-10-17 |
| DE2511968A1 (en) | 1975-09-25 |
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