US3692831A - Counter-current cycling extraction - Google Patents

Counter-current cycling extraction Download PDF

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Publication number
US3692831A
US3692831A US863879A US3692831DA US3692831A US 3692831 A US3692831 A US 3692831A US 863879 A US863879 A US 863879A US 3692831D A US3692831D A US 3692831DA US 3692831 A US3692831 A US 3692831A
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United States
Prior art keywords
stream
solvent
solute
heavy
light
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Expired - Lifetime
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US863879A
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English (en)
Inventor
Chandrasekhara Rao Darsi
John Edwin Feick
Isa Christopher Mustaklem
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Celanese Canada Inc
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Chemcell Ltd
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Publication date
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D11/00—Solvent extraction
    • B01D11/04—Solvent extraction of solutions which are liquid
    • B01D11/0484—Controlling means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D11/00—Solvent extraction
    • B01D11/04—Solvent extraction of solutions which are liquid
    • B01D11/0426—Counter-current multistage extraction towers in a vertical or sloping position
    • B01D11/043—Counter-current multistage extraction towers in a vertical or sloping position with stationary contacting elements, sieve plates or loose contacting elements
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • C07C51/48—Separation; Purification; Stabilisation; Use of additives by liquid-liquid treatment

Definitions

  • ABSTRACT A counter-current cycling extraction method wherein a light solvent upward stream extracts a solute from a heavy solvent downward stream, the improvement which comprises during the circulation of said light solvent upward stream simultaneously circulating an upward stream of the heavy solvent whose solute has 4 Claims, 1 Drawing PATENTEI] SEP 1 9 I972 HEAVY PHASE LIGHT PHASE LIGHT PHASE PRODUCT HEAVY PHASE PRODUCT INVENTORS Chundrosekhoro Ruo DARSI John Edwin FEICK lsu Christopher MUSTAKLEM PATENT AGENTS 1 COUNTER-CURRENT CYCLING EXTRACTION
  • This invention relates to. a counter-current, cycling extraction method where the transfer of solute is from a heavy phase to a light phase and the apparatus therefore.
  • Counter-current extraction is generally accomplished by the simultaneous flow of two substantially immiscible streams, a heavy one comprising 'a heavy solvent and a light one comprising a light solvent, fonning two phases, one of said phases containing at least one solute to be transferred from one stream to the other.
  • Such methods are used for the separation or extraction of the components of a solution.
  • a countercurrent cycling extraction method whereby a solute is transferred from a heavy solvent stream to a light solvent stream, the said two streams being substantially immiscible into one another, the process comprising alternatively pressuring down a stream of heavy solvent containing a solute into a zone and then pressuring up into said zone through said heavy solvent, a stream of light solvent to remove from said heavy solvent, said solute, and simultaneously collecting in alternate order from said zone, near the bottom an amount of heavy solvent stream having reduced solute concentration substantially corresponding to the amount of heavy solvent which is simultaneously fed, and during the light solvent flow collecting from the top of the zone a solute-enriched light stream, while feeding into said zone near the bottom and into the heavy solvent stream, an amount of said heavy solvent of reduced solute concentration corresponding substantially to the volume increase of the light solvent stream due to the solute transfer to maintain the volume of the heavy solvent stream constant throughout the extraction method.
  • outlet means to take out respectively, the light stream containing solute, and the heavy solvent stream having reduced solute concentration
  • c. means co-operating with said feeding means and said outlet, means for cyclically opening and closing said heavy solvent feeding means and outlet, while cyclically closing and opening said light solvent feeding means and outlet;
  • compensating means for feeding a controlled amount of the solvent having reduced solute concentration into the base of said extraction column during the flow of the light solvent.
  • 10 designates an extraction column, partially shown in exploded view, and having enlarged ends to promote settleing, and in which some of the perforated plates, such as sieve trays l2, l3 and 14, may be seen defining stages with the walls of column 10.
  • the perforations of these plates should be small so as to affect efficient contact.
  • Other contacting means, such as packing, may be added if desired.
  • a light phase is introduced into the lower portion of the column 10 via line 16 and a heavy phase into the upper portion of the column 10 via line 18.
  • the driving forces to enable the flow of said phases into two streams in the extractor 10, are gravity and pressure. This latter force (pressure) is described at greater length herein below.
  • the interface between the light and the heavy phase may be seen; for instance, at 19 or 20.
  • the light phase reaches the overhead of extractor, itescapes via line 21 and may be collected by any means; for instance, it may be kept in a reservoir 22; while the heavy phase escapes at the bottom of the column via line 24.
  • the line 21 is also provided with a vent 23 for the escape of gases and safety purposes.
  • Line 18 ends below 21, and line 16 above 24 to in- II'AIAQA MAI:
  • Lines 16 and 18 are also provided, respectively, with valves 34 and 44, and flowmeasuring devices 33 and 43.
  • the flow in line 16 actuates the flow measurement device 33 which, in turn, feeds a signal into a flow-regulating control 35 via a transmitter 36.
  • the flow-regulating control 35 controls the valve 34 to maintain the required flow in line 16 by means of the pneumatic line 37.
  • flow-regulating control 45 pneumatically actuating valve 44 according to the signal received from the flow measuring device 43 via the transmitter 46.
  • the on-off solenoid valves 38 and 48 are actuated cyclically by a cycletimer 50 which generates electrical signals along lines 35 and 45 to 38 and 48 for pneumatically closing and opening in alternate order, valves 34 and 44 so that one phase forming a stream is flowing at a time.
  • this flow at each cycle of each stream takes the form of alternating square waves or approximations of them.
  • line 24 is provided with a pump 60 to remove the heavy solvent stream having reduced solute concentration and feed into a reservoir 61 via line 62.
  • the overflow of heavy solvent in 61 may be kept in a storage tank 63 or delivered where necessary.
  • Line 62 is provided with an onoff valve 58 operated by the electrical signals generated from line 45 by the cycle timer 50 so that valves 64 and 44 be both opened at the same time.
  • a level control 65 pneumatically regulates via 64 the flow of heavy stream in line 24.
  • a Recycling Stream A circulating pump 67 recycles the depleted heavy phase in reservoir 61 via line 70 into the bottom of the extraction column 10.
  • the line 70 is also provided with valves 68 and 72, the latter being activated by the cycle timer 50 by line 35 so that both valves 72 and 34 by opened at the same time.
  • the flow through valve 72 is also controlled by a flow controlling device as previously described.
  • Theoretical Consideration Involving the Transfer of Solute From Heavy to Light Phase
  • the flow of the phases in extraction columns is due to pressure and gravity. If a certain amount of heavy phase is introduced near the top of the column and the light phase line shutoff, the heavy liquid will reach the bottom of the column, given enough time. If the light phase is flowing up the column simultaneously, the flow of heavy phase down the column can generally be stopped, given a high enough flow rate of the light phase; this is also known as flooding. Flooding is to be avoided as it disrupts the aims of such apparatus. In a controlled cycling extractor, only one phase is flowing at a time. During the light phase flow period, a certain amount of pure, light solvent is introduced into the bottom section of an extraction column.
  • the liquid mixes with the mixture of heavy solvent and solute present in that stage and some of the solute is dissolved into the light phase, and its volume increases as a result.
  • the volume of liquid leaving this stage to the nexthigher one is equal (in this short period of flow) to the volume introduced, and hence there is a net gain of light phase in the bottom of the extraction column.
  • the process occurs in all the consecutive stages and the volume of light phase leaving as an overflow at the top of the column is equal to the amount introduced.
  • the gain on the light phase volume by virtue of solute transfer remains in the column.
  • a mixture of heavy solvent and solute is introduced at the top of the column, mixes with the light phase and some transfer of solute to the light phase occurs.
  • the mode of operation is by drawing heavy phase out at the base.
  • the amount of base product that should be necessary to draw at the bottom is the volume of heavy phase that would reach the base after going through transfers at various stages. This means that successively less amounts of heavy phase must pass through successive stages. Since the bulk flow through the column is governed by what is drawn off at the bottom, the excess amount (which is equal to the volume of the solute) introduced at the top will stay at the top of the column.
  • the difficulty encountered in forcing more light phase up the column than the amount introduced at the bottom is taken care of during the light phase flow I n i A Min increase in the light phase due to solute transfer.
  • the light phase introduced forces an equal volume of light phase through the successive higher stages; in addition, the heavy phase recycle introduced will force an equal volume of light phase up the column which also is the amount of light phase that would be formed during its travel up the column.
  • TAB LE 1 the column is greatly enhanced during cyclic operation and comparisons may be made with conventional operations showing efficiencies at least 100 percent greater and a capacity increase of at least percent over the flooding point for this system.
  • a counter-current cycling extraction method whereby a solute is transferred from a heavy solvent stream to a light solvent stream, the said two streams being substantially immiscible into one another, the process comprising alternatively pressuring down a stream of heavy solvent containing a solute into a zone and then pressuring up into said zone and through said heavy solvent, a stream of light solvent to remove from said heavy solvent said solute, and simultaneously collecting, in alternate order from said zone near the bottom, an amount of heavy solvent stream having reduced solute concentration substantially corresponding to the amount of heavy solvent which is simultanet s xfa ta lsl7dwinslha blsalysm fl stias Discussion It can be easily seen from Table I that efficiency of Acetic acid conc. (weight percent) Volum Total flow Light phase Heavy phase throughratio Effiput, USG/ heavy] Entering Leaving Entering Leaving ciency, No. hit/it. light (at 16) (at (at 18) (at 24) percent

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Extraction Or Liquid Replacement (AREA)
US863879A 1969-10-06 1969-10-06 Counter-current cycling extraction Expired - Lifetime US3692831A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US86387969A 1969-10-06 1969-10-06

Publications (1)

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US3692831A true US3692831A (en) 1972-09-19

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US863879A Expired - Lifetime US3692831A (en) 1969-10-06 1969-10-06 Counter-current cycling extraction

Country Status (4)

Country Link
US (1) US3692831A (enrdf_load_stackoverflow)
DE (1) DE2049097A1 (enrdf_load_stackoverflow)
FR (1) FR2065009A5 (enrdf_load_stackoverflow)
GB (1) GB1266636A (enrdf_load_stackoverflow)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9201501D0 (en) * 1992-01-24 1992-04-08 British Nuclear Fuels Plc A solvent extraction system

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2647856A (en) * 1952-06-09 1953-08-04 Universal Oil Prod Co Apparatus and process for countercurrent liquid-fluid extraction
US2729550A (en) * 1951-11-09 1956-01-03 Shell Dev Method and apparatus for contacting liquids by reciprocal dispersion
US2767068A (en) * 1954-03-03 1956-10-16 Shell Dev Method and apparatus for contacting liquids by reciprocal dispersion
US3261672A (en) * 1960-05-23 1966-07-19 Buckau Wolf Maschf R Countercurrent extraction process
US3408051A (en) * 1966-02-23 1968-10-29 Mixing Equipment Co Inc Column mixing apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2729550A (en) * 1951-11-09 1956-01-03 Shell Dev Method and apparatus for contacting liquids by reciprocal dispersion
US2647856A (en) * 1952-06-09 1953-08-04 Universal Oil Prod Co Apparatus and process for countercurrent liquid-fluid extraction
US2767068A (en) * 1954-03-03 1956-10-16 Shell Dev Method and apparatus for contacting liquids by reciprocal dispersion
US3261672A (en) * 1960-05-23 1966-07-19 Buckau Wolf Maschf R Countercurrent extraction process
US3408051A (en) * 1966-02-23 1968-10-29 Mixing Equipment Co Inc Column mixing apparatus

Also Published As

Publication number Publication date
GB1266636A (enrdf_load_stackoverflow) 1972-03-15
FR2065009A5 (enrdf_load_stackoverflow) 1971-07-23
DE2049097A1 (de) 1971-05-27

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