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GB2078538A - Pulsed annular columns for counter-flow contact of two phases - Google Patents

Pulsed annular columns for counter-flow contact of two phases Download PDF

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Publication number
GB2078538A
GB2078538A GB8120525A GB8120525A GB2078538A GB 2078538 A GB2078538 A GB 2078538A GB 8120525 A GB8120525 A GB 8120525A GB 8120525 A GB8120525 A GB 8120525A GB 2078538 A GB2078538 A GB 2078538A
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United Kingdom
Prior art keywords
column
annular
phase
phases
plates
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Granted
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GB8120525A
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GB2078538B (en
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Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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Publication of GB2078538A publication Critical patent/GB2078538A/en
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Publication of GB2078538B publication Critical patent/GB2078538B/en
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D11/00Solvent extraction
    • B01D11/02Solvent extraction of solids
    • B01D11/0261Solvent extraction of solids comprising vibrating mechanisms, e.g. mechanical, acoustical
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D11/00Solvent extraction
    • B01D11/04Solvent extraction of solutions which are liquid
    • B01D11/0426Counter-current multistage extraction towers in a vertical or sloping position
    • B01D11/043Counter-current multistage extraction towers in a vertical or sloping position with stationary contacting elements, sieve plates or loose contacting elements
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D11/00Solvent extraction
    • B01D11/04Solvent extraction of solutions which are liquid
    • B01D11/0426Counter-current multistage extraction towers in a vertical or sloping position
    • B01D11/0438Counter-current multistage extraction towers in a vertical or sloping position comprising vibrating mechanisms, electromagnetic radiations

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Mechanical Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Treatment Of Liquids With Adsorbents In General (AREA)
  • Extraction Or Liquid Replacement (AREA)

Abstract

A pulsed annular column for use, in particular, in the re-processing of irradiated fuels, comprises an outer cylindrical envelope (1) arranged with its axis vertical, wherein is placed a cylindrical core (3) which, together with said envelope (1) delimits an upper portion (I) of annular cross-section provided with means (5) for introducing a heavy phase and with means (7) for discharging a light phase; a central portion (II) of annular cross-section provided with a packing constituted by annular baffles (21,23) for contacting said phases on a counter-flow basis; and a lower part (III) of annular cross-section provided with means (13, 13') for introducing the light phase, means (15, 15') for discharging the heavy phase and means (11) for setting up pulsations in the mixture of said phases. <IMAGE>

Description

SPECIFICATION Pulsed annular columns for counter-flow contact of two phases The present invention relates to a pulsed annular column for contacting, on a counter-flow basis, two phases constituted by two immiscible liquids, by a liquid and a gas, or by a liquid and a particulate solid.
The known pulsed columns generally comprise: an upper portion provided with an inlet for the heavy phase and an outlet for the light phase; a central cylindrical portion arranged with its axis vertical, provided with a packing constituted, for example, by perforated plates; a lower portion comprising an inlet for the light phase and an outlet for the heavy phase; and a pulsing system which enables a reciprocating movement to be imparted to both of the phases present in the column.
The pulsing system generally used is constituted by a vertical tube which is outside the column and partly filled with the continuous phase, the lower end of this tube communicating with the lower portion of the column, and the upper end of this tube being connected to a compressed-air source adapted to apply periodic pressure to the surface of the continuous phase present in the tube, so as to impart a reciprocating movement to both of the phases present in the column.
Columns of the above-mentioned type have numerous applications, particularly in the nuclear field where they are often used for the treatment of solutions of irradiated fuels by extraction with solvents. In this application, the risk of the occurrence of a nuclear chain reaction within the liquids present in the column, sets certain limitations, particularly as regards the dimensions of the column and the concentrations of plutonium in the treated solutions.
To avoid this drawback, it has been proposed to make use of annular columns which, because of their particular geometry, enable the volume of materials under treatment to be increased, while meeting the need for nuclear safety.
However, the known annular columns, which comprise a conventional packing constituted by perforated plates, do not enable a separation efficiency to be achieved that is comparable with that of the conventional cylindrical columns having the same cross-section.
The precise object of the present invention is to provide an annular pulsed column which, in particular, offers the advantage of leading to separation efficiency which is at least as good as that of the cylindrical columns of the conventional type.
According to the invention, the annular pulsed column for contacting, on a counter-flow basis, two phases, at least one of which is a liquid phase, comprises: an outer cylindrical envelope arranged with its axis vertical, wherein is placed a cylindrical core which, together with said envelope delimits, within the outer column, an upper portion of annular cross-section provided with means for introducing a heavy phase and with means for discharging a light phase; a central portion of annular cross-section provided with a packing for contacting said phases on a counter-flow basis; and a lower part of annular cross-section provided with means for introducing the light phase, means for discharging the heavy phase and means for setting up pulsations in the mixture of said phases, and the column is characterized in that said packing is constituted by annular plates which are disposed horizontally and spaced from each other in the vertical direction, each of said plates occupying only a portion of the cross-section of said central portion and being divided into a first series in contact with the central cylindrical core by way of their peripheries, and a second series in contact with the outer envelope of said column by way of their peripheries, the plates of the first series being interposed between the plates of the second series.
According to the invention, when the column is intended for use in the treatment of radioactive solutions, the central core advantageously comprises a material which absorbs or decelerates the neutrons.
To quote an example, the central core may be constituted by a recipient filled with a solution of material which absorbs or decelerates the neutrons, such as cadmium, boron or gadolinium, or it may be constituted, at least partially, by a solid material which absorbs or decelerates the neutrons, such as polyethylene, carbon, boron-containing concrete, boron carbide, boron, cadmium, hafnium or boron steel.
The central core preferably comprises a stack of cylindrical bodies made of neutron-absorbing concrete.
According to the invention, the means for setting up pulsations in the column advantageously comprise a tube which communicates laterally with the lower portion of the column.
The annular pulsed column as defined above offers the following advantages in particular.
- Its annular shape and the presence of a neutron-absorbing core render it possible to obtain a sectioned column which has a suitable width of annulus and therefore an increased capacity, which column is safe as regards nuclear criticality and is consequently of very considerable interest to works in which irradiated fuels are reprocessed; -the use of a packing constituted by annular plates forming baffles is particularly well suited to the annular geometry, since it permits continuous lateral distribution of the material flowing through the column while, at the same time, regularizing the range of flow-rates of the fluids, which enables efficiency and performance to be obtained that are comparable with those of the cylindrical columns of the conventional type; and -the fact that pulsations are set up in the column by way of a tube terminating laterally and at right angles to the outer envelope enables correct functioning to be ensured, while at the same time leaving the base of the column free for supporting the cylindrical core of neutron-absorbing material; furthermore, as a result of this lateral positioning of the pulsing tube, the lower portion of the column may have a widened zone which may form a zone for preventing entrainment or effecting decantation and coalescence of the heavy phase before it leaves the column.
Other advantages and features of the invention will emerge more clearly from perusal of the following description, which is provided as a non-limiting example and which makes reference to the single annexed Figure which illustrates diagrammatically and in vertical section an annular pulsed column in accordance with the invention.
This Figure shows that the annular column comprises an outer cylindrical envelope 1 which is arranged with its axis vertical and in which is coaxially arranged a cylindrical core 3 which, together with the said envelope 1, delimits, within the column, an upper portion I of annular cross-section, a central portion 11 of annular cross-section and a lower portion Ill of annular cross-section.
The heavy phase is introduced into the upper portion of the column through two diametrically opposed pipes 5, and the light phase is discharged through two diametrally opposed pipes 7 which are provided with vents 9 and which communicate with the column at a higher level than the pipes 5.
At its lower portion, the column is connected to a system for setting up pulsations by way of a single tube 11 which communicates laterally with the lower portion Ill of the column and at right angles to the outer envelope 1.
This tube 11 is connected by a vertical portion 11 b to means for setting up pulsations on the surface of the continuous phase present in this tube, which means may be constituted by a compressed-air source adapted to apply periodic pressure so as to impart a reciprocating movement to the phases present in the column.
The light phase is introduced at the lower portion of the column either through two diametrically opposed pipes 13 which communicate with the lower portion Ill of the column at a level higher than that of the tube 11 or, in the case where operations are on the basis of a continuous light phase, through a pipe 13' which communicates with the tube 11. The heavy phase is discharged from the lower portion of the column through two diametrically opposed pipes 15 which communicate with the lower portion 1(1 of the column at its lower end.
However, in certain cases, the heavy phase may be discharged through a single pipe 15' which communicates with the lower portion Ill, this arrangement being used particularly when low rates of flow are involved.
In the embodiment illustrated in this Figure, the central core 3 comprises a recipient 3a in which is arranged a stack of cylindrical bodies 3b made of neutron-absorbing concrete.
Furthermore, the central core 3 and the outer envelope 1 are widened at their upper and lower ends so that the upper portion land the lower portion Ill of the annular column are substantially bellshaped and also comprise a zone having an annular cross-section greater than that of the central portion, the width of this annular zone, however, being sub stantiallythe same as that of the central portion so asto meetthe requirements regarding nuclear safety. Thus, at the ends of the column are formed zones which are favourable for preventing entrainmentor for effecting decantation and coalescence of the heavy phase or the light phase before they leave the column.
However, it should be pointed out that in certain cases it is not necessary to provide a zone of greater cross-section at the lower end of the column, particularly whers the heavy phase is extracted through rhe pipe 15'.
In its central portion II, the column comprises a packing constituted by annular plates 21 and 23 which are arranged horizontally and are spaced from each other in the vertical direction. The plates 21 and 23, each of which is in the form of a ring, occupy only part of the cross-section of the central portion II of the column, and these plates are divided into a first series of plates 21 in contact, by their peripheries, with the outer envelope 1 of the column and into a second series of plates 23 in contact, by their peripheries, with the outer wall 3a of the cylindrical core 3, the plates 21 of the first series being interposed between the plates 23 of the second series so as to form annular baffles along the path of travel of the fluids circulating in the column.In this central portion the column may be provided with more than two intermediate diametrally opposed pipes 25 for introducing the light phase.
It should be stated that, according to the invention, the gape between two adjacent plates 21 and 23 is selected to su it the nature of the phase that constitutes the continuous phase.
To quote an example, when this continuous phase is constituted by the heavy phase, for instance by an aqueous phase, good results are obtained with a gap of approximately 40 mm. When the continuous phase is the light phase, for example an organic phase, good results are obtained with a gap of approximately 20 mm.
The annular column in accordance with the invention may operate when the continuous phase that is used is either the heavy phase or the light phase.
When operations are carried out on the basis of a continuous heavy phase, the light phase is introduced through the two pipes 13, and the heavy phase through the two pipes 5. After it has circulated in the column, the light phase is discharged through the pipes 7, and in this case the lower portion I acts as a decantation and coalescent zone for the light phase. The heavy phase is extracted from the column at a controlled rate through the two pipes 15 after having passed through the lower portion Ill which in this case performs the function of a zone for preventing entrainment of the heavy phase. f However, when the discharge is small, the heavy phase may be extracted through the pipe 15', and in this casethe lower portion of the column does not have a widened shape having a zone of greater cross-section.
When operations proceed on the basis of a,con- tinuous light phase, the heavy phase is introduced through the pipes 5 and the light phase is introduced either through the pipes 13 or through the pipe 13' communicating with the pulsation tube 11.
After it has passed into the central portion of the column, the heavy phase is extracted at a regulated rate through the pipes 15; in this case the lower por tion Ill of the column performs the function of a decantation and coalescence zone for the heavy phase. The light phase is discharged through the pipes 7 after having passed through the upper portion I which performs the function of the zone for preventing entrainment of the light phase.
H#wever, it is not necessary for the lower portion Ill of the column to have the shape of a down-turned bell, since it is just as possible to extract the mixture oftlfetwo unseparated phases through the pipe 15' and to direct it towards a decanter outside the column; the light phase is recovered from this decanter and is passed to the base of the column either through the pipes 13 or the pipes 13'.
By way of example, there are given below the results obtained in experiments for testing the operation of an annular column in accordnace with the invention in the treatment of two phase, one constituted by a nitric acid solution or by a nitric solution of uranyl nitrate, which forms the heavy phase, and the other by tributyl phosphate 30% diluted in dodecane, which forms the light phase.
The column used was of the following dimensions in its central portion: -width ofannulus: 8 cm, - diameter of central cylindrical core: 29 cm, - height of central portion: 8 m.
The packing was constituted by stainless steel annular baffles having an axial clearance of 25% and arranged, as indicated in the Figure, with a gape of 40 mm between them.
It should be stated that axial clearance is defined for each baffle by the ratio of the cross-section of the central portion 11, not occupied by the baffle, to the total cross-section of this central portion.
To check the performance of the column, various tests were carried out at 300C while operating either on the basis of a continuous organic phase or of a continuous aqueous phase.
In these tests, efficiency measurements were carried out after establishing concentration curves at different levels in the column, and this efficiency was evaluated in terms of height equivalent to a theoretical stage - HETS. Also, measurements were made of the total specific deliveries and the retention rate of the dispersed phase which corresponds to the percentage by volume of the dispersed phase present in the column.
The results obtained are shown in Table 1 below.
For comparison purposes, the same tests were carried out in this annular column but with the packing replaced by a packing of perforated plates occupying the entire cross-section of the central portion and formed by stainless steel plates having nozzles, the diameter of the holes in which being 3 mm, the pitch 6 mm and the spacing of the plates being 50 mm.
The results obtained in this case are shown in Table 2 below.
In view of the results given in these two Tables, it can be confirmed that the use of annular baffles enables the efficiency of the annular column to be very considerably improved.
Furthermore, following measurements carried out on the light phase and the heavy phase with the aid of radio-active tracers, it was possible to confirm that the rate curve was very irregular with the packing consisting of plates with nozzles, whereas it was much more uniform with the packing comprising annular plates as used in the invention.
TABLE 1
Aqueous solution Ration of volume Continuous Total Retention H E T S of aqueous phase specific rate (m) phase to that deliveries (%) U content Normality of organic 1.h-' cm (9.1-' ) phase 3.98 0.2 organic 2.0 11.2 0.66 - 4.0 0.2 aqueous 3.0 22.0 0.80 177 3.16 0.51 organic 2.0 9.7 1.17 175 2.9 0.51 aqueous 2.0 18.0 0.56 TABLE 2
t Aqueous solution Ration of volume Continuous Total Retention H ETS of aqueous phase specific rate (m) - phase to that deliveries (%) U content Normality of organic 1.h-' cm-2 (g.l ) phase 3.1 phase tothat organic deliveries 2.0 173 3.1 0.51 organic 2.00 13.2 8.0 17 0.51 2.00 13.2 8.0

Claims (8)

1. A pulsed annular column for contacting, on a counter-flow basis, two phases, at least one of which is a liquid phase, which column comprises: an outer cylindrical envelope (1 ) arranged with its axis vertical, wherein is placed a cylindrical core (3) which, together with said envelope (1) delimits, within said column, an upper portion (I) of annular cross-section provided with means (5) for introducing a heavy phase and with means (7) for discharging a light phase; a central portion (II) of annular cross-section provided with a packing (21, 23) for contacting said phases on a counter-flow basis; and a lower portion (III) of annular cross-section provided with means (13, 13') for introducing the light phase, means (15, 15') for discharging the heavy phase and means (11) for setting up pulsations in the mixture of said phases, which column is characterized in that said packing is constituted by annular plates (21,23) which are disposed horizontally and spaced from each other in the vertical direction, each of said plates occupying only a part of the cross-section of said central portion (II) and being divided into a first ;;eries (23) in contact with the central cylindrical core 3) by way of their peripheries, and a second series [ 21) in contact with the outer envelope (1) of said column by way of their peripheries, the plates of the First series being interposed between the plates of the second series.
2. A column according to Claim 1, characterized in that the central core (3) comprises a material which absorbs or decelerates the neutrons.
3. Acolumn according to Claim 2, characterized in that the central core (3) comprises a stack of cylindrical bodies (3b) made of neutron-absorbing concrete.
4. A column according to any one of Claims 1 to 3, characterized in that the means for setting up pulsations in the mixture of said phases comprise a tube (11) which communicates laterally with the lower portion (III) of said column (5).
5. A column according to Claim 4, characterized in that the means for introducing the light phase are constituted by a pipe (13') communicating with said tube.
6. A column according to any one of Claims 1 to 5, characterized in that the upper portion (I) comprises a zone having an annular cross-section which is greater than that of the central portion (II), and in thatthe means for discharging the light phase are constituted by two diametrically opposed pipes (7) communicating with said zone.
7. A column according to any one of Claims 1 to 6, characterized in that the lower portion (III) of the column comprises a zone having an annular crosssection greater than that of the central portion (II) and in that the means for discharging the heavy phase are constituted by two diametrally opposed pipes (15) communicating with said zone.
8. A pulsed annular column for counter-flow con- tact of two phases, substantially as described herein with reference to the accompanying drawing.
GB8120525A 1980-07-03 1981-07-02 Pulsed annular columns for counter-flow contact of two phases Expired GB2078538B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR8014837A FR2485941B1 (en) 1980-07-03 1980-07-03 ANNULAR PULSED COLUMN

Publications (2)

Publication Number Publication Date
GB2078538A true GB2078538A (en) 1982-01-13
GB2078538B GB2078538B (en) 1984-03-07

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GB8120525A Expired GB2078538B (en) 1980-07-03 1981-07-02 Pulsed annular columns for counter-flow contact of two phases

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FR (1) FR2485941B1 (en)
GB (1) GB2078538B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2276559A (en) * 1993-03-29 1994-10-05 British Tech Group Processing of liquid/solid mixtures using pulsations
RU2183979C1 (en) * 2000-03-27 2002-06-27 Открытое акционерное общество "Алюминий Казахстана" Method of hydrochemical processing of solid agent and reactor for realization of this method

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2576804B1 (en) * 1985-02-07 1987-03-06 Commissariat Energie Atomique PULSED ANNULAR COLUMN OF LIQUID-LIQUID EXCHANGE SUITABLE FOR SIMULTANEOUSLY PERFORMING ELECTROLYSIS
RU2457897C2 (en) * 2010-11-08 2012-08-10 Открытое акционерное общество "Русский магний" Filling for pulsation columns of raw stock leaching by heated aggressive acids

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2144797A (en) * 1936-07-11 1939-01-24 Mid Continent Petroleum Corp Method of and apparatus for extracting constituents of mineral oils
NL67932C (en) * 1948-06-18
NL292467A (en) * 1962-05-09
NL131266C (en) * 1962-05-30 1970-12-15 Shell Int Research Device and method for intensively bringing two or more phases into contact with each other
FR1376103A (en) * 1962-12-14 1964-10-23 Atomic Energy Commission Solvent extraction apparatus
US3854176A (en) * 1971-09-29 1974-12-17 Atlantic Richfield Co High capacity geometrically-favorable solvent extraction columns for processing fissile materials
FR2429608A1 (en) * 1978-06-27 1980-01-25 Eries Pulsed column liq.-liq. or gas-liq. extractor - has combination of disc-and-doughnut baffles and perforated plates between them increasing the efficiency in large column

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2276559A (en) * 1993-03-29 1994-10-05 British Tech Group Processing of liquid/solid mixtures using pulsations
RU2183979C1 (en) * 2000-03-27 2002-06-27 Открытое акционерное общество "Алюминий Казахстана" Method of hydrochemical processing of solid agent and reactor for realization of this method

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Publication number Publication date
FR2485941A1 (en) 1982-01-08
BE889468A (en) 1981-11-03
GB2078538B (en) 1984-03-07
FR2485941B1 (en) 1988-07-29

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 19930702