Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D1/00—Evaporating
  • B01D1/16—Evaporating by spraying
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D1/00—Evaporating
  • B01D1/30—Accessories for evaporators ; Constructional details thereof
  • B01D1/305—Demister (vapour-liquid separation)
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D15/00—Separating processes involving the treatment of liquids with solid sorbents; Apparatus therefor
  • B01D15/08—Selective adsorption, e.g. chromatography
  • B01D15/10—Selective adsorption, e.g. chromatography characterised by constructional or operational features
  • B01D15/24—Selective adsorption, e.g. chromatography characterised by constructional or operational features relating to the treatment of the fractions to be distributed
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D15/00—Separating processes involving the treatment of liquids with solid sorbents; Apparatus therefor
  • B01D15/08—Selective adsorption, e.g. chromatography
  • B01D15/26—Selective adsorption, e.g. chromatography characterised by the separation mechanism
  • B01D15/40—Selective adsorption, e.g. chromatography characterised by the separation mechanism using supercritical fluid as mobile phase or eluent

Definitions

• the present invention relates to a method and a separation device, in particular in the field of chromatography.
• Preparative chromatography is a powerful purification technique applied from the laboratory scale (a few milligrams to a few grams) on an industrial scale (production of several hundred tonnes).
• the eluents promoting the separation of fractions of a mixture are generally liquid solvents.
• supercritical or subcritical solvents for example carbon dioxide
• a chromatographic device is composed of one or more columns and allows, following the injection of a mixture to collect several fractions. For each of these collections, the separation between the fractions and the gaseous carbon dioxide must be optimized to ensure a good yield of the isolated fractions and avoid entrainment of the fractions in the gas stream.
• the eluent can be recycled. This implies, however, very strong constraints on the purity of the recycled eluent; indeed, any traces of fractions of the products separated by chromatography in the eluent reinjected into the chromatography system may contaminate the fractions to be isolated.
• Document FR-A-2 584 618 describes a device for the implementation of extraction-separation-fractionation processes using supercritical fluids.
• the extraction-separation-fractionation device using a fluid or a supercritical fluid mixture which contains the substances to be extracted and / or separated and / or fractional and which is passed through a device for reducing its density is characterized by the fact that immediately at the outlet of this reducing device, the fluid is brought tangentially into a cyclonic chamber
• the charge to be treated is not very soluble in the Caibone dioxide, it has been proposed to use not a pure solvent but a mixture comprising on the one hand a solvent conventionally used in supercritical fluid chromatography. That is to say in the majority of cases the caibon dioxide and a conventional liquid solvent (alkanes, chlorinated solvents, alcohols, ketones, etc.)
• This conventional liquid solvent which is added to the supercritical solvent is called "coach” because it allows for example significantly increase the solubility of some families of molecules by changing the polarity of the chromatographic eluent which will thus be entrained by the solvent.
• the molecules concerned are, for example, those concerned with liquid chromatography, such as separations of chiral molecules.
• the document FR-A-2 601 883 describes a method and a device for extracting and / or separating and / or preparing products in solution in a fluid in the supercritical state.
• the physical conditions are varied to reduce the density and isolate the dissolved products, the fluid then being returned to its gaseous state.
• the solvent is mixed with up to 10% by weight of the total mixture of a second additive solvent, the process comprising, after isolating the products, a regenerative step in which the mixture is brought into contact with an excess of additive under predetermined pressure and temperature conditions ensuring the readjustment of the composition of the mixture and its recycling - technique inducing a large volume and sometimes very high temperature (greater than 100 0 C).
• the invention proposes a process for separating a fraction containing a supercritical or subcritical solvent and a component, the process comprising the steps of
• the process comprises several separation steps after the expansion step.
• a portion of the liquid phase is separated during a preliminary separation step, with another portion of the mixture subsequently subjected to the coalescence separation.
• the preliminary step is a step of separating the liquid phase by centrifugation of the mixture.
• the preliminary step is a preliminary step of separating the liquid phase by gravity.
• the steps of separation by coalescence and by gravity are carried out in the same column.
• the mixture has an upward movement in contact with the demister.
• a countercurrent of a liquid rinsing phase is applied to the movement of the mixture.
• the rinsing liquid phase is a part of condensed solvent.
• a temperature gradient is applied to the mist separator, a portion of the solvent gas phase is condensed in the rinse liquid phase in a cold zone of the mist separator.
• the upper end of the mist separator is a cooler zone than the lower end of the hotter mist separator, the method comprising, after the expansion step and before the coalescence separation step, an injection step mixing at the warmer end of the mist eliminator.
• liquid phase droplets of 10 ⁇ m or more are separated during a preliminary separation stage and droplets of less than 10 ⁇ m are separated during the coalescence separation stage.
• the invention also relates to a device for separating a fraction containing a supercritical solvent and a component, the device comprising
• a separator adapted to separate the liquid phase from the gas phase.
• the device includes a warmer zone at a lower end of the macerator and a cooler zone at an upper end of the mister.
• the device further comprises a cyclonic chamber, the mist separator being connected to an outlet of the cyclonic chamber.
• the invention further relates to a chromatography apparatus comprising a central separation unit on a chromatographic ht,
• At least one drift fraction withdrawal line the fraction containing a supercritical or subctictic solvent and a component
• the demesculator being adapted to separate the fraction expanded by the expander in the form of a mixture of a liquid component phase and a solvent gas phase
• the apparatus further comprises a cyclonic chamber between the expander and the mist separator, the cyclonic chamber partially separating the liquid component phase from the solvent gas phase.
• the apparatus comprises
• fractions withdrawal lines the fractions containing a supercntic or subc ⁇ tic solvent and a component
• each withdrawal line the expander being adapted to relax each fraction in a mixture of a liquid component phase and a solvent gas phase
• a cyclonic chamber on each withdrawal line, the cyclonic chamber being adapted to partially separate the liquid component phase from the mixture
• mist separator being connected to all the cyclonic chambers, the mist separator being adapted to separate the liquid component phase and the solvent gas phase from the mixture
• FIG. 1 an example of a device FIG. 3, another example of a separating device, FIG. 4, a further example of a separation device.
• FIG. 4 a further example of a separation device.
• an eluent In a process for the separation of components in a chromatography apparatus, an eluent.
• the chromatography can be carried out with a supercntic solvent
• a supercntic state is called a state characterized by a pressure and a temperature respectively greater than the pressure and the critical temperature of the body in the case of a pure body, ie with a pressure and a temperature respectively greater than and the critical temperature of the mixture in the case of a mixture
• the superc ⁇ tic fluids have remarkable properties with respect to liquids, in particular a lower viscosity and a greater diffusivity, which improves the separation by chromatography. Chromatography can also be applied.
• non-superctic fluids called “subcritical” it is due in a state characterized either by a pressure greater than the critical pressure and a temperature below the critical temperature in the case of a pure body, or by a pressure higher than the critical pressures of each of the components of the mixture in the case of a mixture (at this subject, reference is made to the journal Information Chimie 321, October 1990, pages 166 to 177, article by Michel PERRUT "supercritical fluids, applications in abundance”).
• fractions of components are collected, the fractions comprising the component in solution in the solvent used for the chromatography.
• the solvent used for the chromatography.
• the invention relates to a method for separating a fraction containing a supercritical or subcritical solvent (in mixture or not with a co-solvent) and at least one component.
• the retention times of the products in the columns are influenced by the eluating force.
• the eluent force can be modified, for example, by pressure, temperature and the content of one or more "trainers".
• the process comprises a step of expansion of the fraction, the expansion of the supercritical or subcritical solvent at the output of chromatography to recover the purified component without carbon dioxide passed in the gaseous state.
• the fraction is expanded to a mixture comprising a component liquid phase and a solvent gas phase.
• the purpose of the relaxation is to recover for example CO2 in the gaseous state.
• the expansion consists mainly in a drop in pressure below the critical pressure of the gas alone (in the case of CO2 an embodiment is to go to 40 bar).
• the expansion device is generally composed of a pressure reducer to reduce the pressure, which also causes the temperature drop and a heating system, because the temperature having lowered, to avoid having CO2 in the liquid state, it is necessary to heat so that the fluid 14 is at a temperature greater than 25-30 0 C.
• the method also includes a step of separating the liquid phase by coalescing the liquid phase with a stripper.
• the method makes it possible to obtain in a simple manner effective separation of the component and the solvent, which makes it possible to increase the yield of obtaining the component and to recycle the solvent.
• FIG. 1 shows an example of a device 10 for separating a component phase 16 from another supercritical or subcritical solvent phase 18 composing a fraction 11 to be separated.
• Fraction 11 is for example derived from a chromatography step during which a fluid comprising several components is separated into fractions of components by elution with an eluent or supercritical solvent. On leaving the chromatography, the fractions comprise a component in solution in a supercritical or subcritical solvent. After the chromatography step, the fraction 11 undergoes expansion in an expander 9, transforming the fraction 11 into a mixture 14 of a gaseous phase of solvent 18 and a liquid phase of component 16.
• the liquid phase is for example a suspension of droplets in the gas phase.
• FIG. 1 shows a step of separation of the mixture 14 by coalescence with a separator 12.
• the liquid phase of component 16 is fixed on the separator 12 and separates from the gas phase. More particularly, the liquid component phase is for example in the form of suspended droplets which are fixed on the mist-splitter and merge into larger droplets. The formation of larger droplets allows flow in the form of liquid film out of the mist separator by gravity.
• a liquid phase film of component 16 flows from the mist separator 12.
• the droplets are for example recovered in a pot 17 under the mist separator, purged continuously or discontinuously.
• the liquid phase of component 16 can thus be evacuated.
• the liquid phase is then separated from the gaseous phase of solvent 18 which is recovered in turn.
• the component 16 of the liquid phase may be a single naturally liquid product, such as oils; when using a "trainer” that is added to the supercritical or subctictic solvent, the component may be a product in solution in the "trainer” also in the liquid phase after expansion.
• the liquid phase therefore comprises at least one component; for simplicity, we will mention later a "liquid phase of component".
• the stripper 12 is a device for circulating the fluid to be treated through a porous solid having a large contact surface.
• the solid may be of different shapes: bulk packing or fabrics or meshes for example metal or ceramic often manufactured in the form of cylinder cartridge.
• An advantage of the mist eliminator 12 is that it allows the separation of a mist of very fine droplets from the liquid phase suspended in the gas phase, as is the case of an aerosol.
• the separator 12 allows the retention of droplets of about 0.1 microns, which allows a good separation of the mixture; the devicator 12 reduces solvent pollution by suppressing fine traces of component in the solvent and increasing the component recovery efficiency.
• the separator separates component droplets that are usually lost and pollute the solvent.
• the separator 12 is for example a packing placed in a separating column 13.
• the column 13 allows the separator to be ordered in an elongated form; the elongated shape of the mist eliminator promotes the contact between the mixture 14 and the mist separator 12, and thus the separation of the mixture 14.
• the column is arranged vertically which allows the mixture in the form of a mist to move in a current The mixture moves upwardly from the bottom of the column 13 in contact with the stripper 12, the mixture gradually getting rid of the liquid component phase.
• the column 13 comprises either an inlet at the bottom of the column under the liquid level (bubbling gas-liquid contact) or an inlet above the liquid level (gas-liquid contact made at the surface of the liquid film dispersed on the packing) by wherein the mixture 14 enters the column 13 and an outlet through which the gas phase 18 of solvent devoid of liquid component phase is recovered.
• the method comprises a step of centrifuging the mixture 14.
• This step is preferably a preliminary separation step for separating droplets of a larger size than the droplets separated by the stripper.
• this preliminary step makes it possible to separate droplets with a diameter equal to or greater than 10 ⁇ m. This step makes it possible to avoid flooding the stripper during the subsequent coalescence step in contact with the stripper.
• the centrifugation step is for example carried out in a cyclonic chamber.
• the chamber 20 is located between the expander 9 and the stripper 12.
• the chamber 20 comprises a side wall 21 and, at one end of the wall, a lower part 22 for collecting the liquid phase 16 from which the liquid can be withdrawn according to the arrow 24 continuously or discontinuously.
• the chamber 20 also comprises at an upper end of the wall, a head 24 forming a plug; the head 24 is pierced axially by a discharge channel 26 which extends into the chamber 20.
• the chamber 20 further comprises an inlet pipe 28 entering the chamber 20.
• the fraction 1 1 is expanded by the regulator 9 in the mixture 14 which enters the chamber 20 through the inlet pipe 28.
• the pipe 28 opens tangentially in the chamber 20, preferably in an upper half of the chamber.
• the chamber 20, of cylindrical cross section, plays the role of cyclone.
• the pipe opens tangentially in the sense that the introduction of the fluid may be perpendicular to the diameter of the chamber at a point in the chamber envelope or that the introduction may be in a rope of the chamber considered in cross section.
• the introduction may be in a plane perpendicular or not to the longitudinal axis of the chamber.
• the chamber 20 comprises a liner for the circulation of a coolant, which ensures the sidewall a suitable temperature to collect the droplets.
• the mixture 14 containing the liquid component phase and the solvent gas phase enters the chamber 20 through line 28 at a linear velocity v; the speed of the mixture 14 in the cylindrical chamber 20 creates a vortex 30.
• component liquid phase droplets separate from the gaseous phase of solvent and flow along the wall 21.
• the droplets are collected in the lower part 22 of the chamber; the liquid component phase is thus a liquid 16 accumulated at the bottom of the chamber 20, then discharged along the arrow 25.
• the evacuated liquid 16 is the component resulting from the separation by chromatography alone, or diluted in a "trainer" during this process. preliminary stage of separation; the device 10 and the method make it possible to increase the yield of the separation by chromatography.
• the combination of a mist eliminator to a cyclonic chamber makes it possible to increase the inlet flow rate of the mixture to a much higher value than in the case of a cyclonic chamber alone where the risk of mechanical entrainment of the liquid increases.
• the combination of a mist eliminator adds a further step that eliminates this undesirable effect.
• the double action separator is characterized by a better performance / size ratio. For a cyclonic chamber of given dimension, one can thus treat higher flow rates - at given flow rate, it is the size of the cyclonic chamber that can be reduced. Thus, the device 10 is smaller than a single cyclone.
• the mixture 14 freed of a portion of the liquid component phase 16 exits through the exhaust channel 26 extending into the chamber 20 in the mixing vortex.
• the liquid and gaseous phases are partially separated.
• Part of the liquid component phase is extracted from the mixture 14.
• the preliminary separation step, in this case by centrifugation, of the mixture allows a pre-separation of the liquid and gaseous phases.
• the partially separated mixture 14 is then conveyed to the separator 12, the mixture then undergoing the step of separation by coalescence in contact with the mist separator 12.
• the mixture 14 conveyed to the mist separator is, for example, a mist of very fine droplets of liquid phase. suspension in the gas phase, such as an aerosol. According to FIG.
• the separator 12 it is conceivable for the separator 12 to be separate and distinct from the cyclonic chamber, in particular the column 13 accommodating the separator 12 is decoupled from the cyclonic chamber 20 and the separator 12 are dissociated modules , but which can be assembled This facilitates the mounting of the device 10
• FIG. 2 shows a variant of FIG. 1, according to FIG. 2, the separator 12 is coupled to the cyclonic chamber.
• the device 10 forms a unitary assembly. The assembly can be obtained by superimposing the modules of FIG.
• the inlet of the column 13 is connected at the outlet of the chamber 20, in particular the inlet of the column 13 is connected to the head 24 of the chamber 20.
• the evacuation channel 26 of the chamber 20 opens into the column 13
• the channel 26 conveys the partially separated mixture 14 to the stripper 12, in the column 13
• the liquid phase component 16 separated by the stripper is recovered in the foot column 13 in the pot 17, rather than at the bottom of the chamber 20 to prevent mixing with the vortex
• the device 10 according to FIG. 2 allows a simpler adjustment of operation
• FIG. 3 shows another example of the separating device 10, the figure showing the expanded fraction in the mixture 14
• the device 10 allows the step of separating the mixture 14 by coalescence with the devicator 12
• the liquid phase of component 16 is fixed on the stripper 12 and separates from the gaseous phase of solvent 18. More particularly, the liquid phase of the component is for example in the form of droplets in suspension which are fixed on the stripper and fuse into larger droplets. The formation of larger droplets allows the formation of larger droplets.
• the devicator 12 is mounted in the column 13 and the droplets are for example recovered in a pot 17 under the stripper 12 at the bottom of the column.
• the liquid phase of component 16 can thus be evacuated. The liquid phase is then separated from the gaseous phase of solvent 18 which is in turn recovered
• the device 10 of FIG. 3 also makes it possible to implement several separation steps As in FIGS. 1 and 2, the mixture undergoes several successive separations, which ensures the advantages indicated above.
• the method comprises a step of separation of the liquid phase by gravity
• This step is preferably a preliminary separation step to separate droplets of a larger size than the droplets separated by the devesicüleur
• this piehminary step makes it possible to separate droplets with a diameter equal to or greater than 300 ⁇ m.
• This preliminary stage has the same advantages as above.
• the preliminary step of separation by gravity is carried out in the interior of the mist separator 12, in the internal volume of the mist separator.
• This preliminary separation step allows the separation of droplets of larger diameter and therefore heavier. These droplets fall at the foot of the stripper and then in the pot 17. This has the advantage of facilitating the implementation of the various separation steps.
• Figure 4 shows another example of a separation device.
• Figure 4 shows an improvement of the column 13 of Figure 1, the fraction being shown relaxed in the mixture 14.
• the column 13 comprises the stripper 12, elongated.
• the mixture 14 is circulated along the stripper 12 so as to cause the coalescence of the liquid component phase 16 in contact with the stripper 12.
• the droplets of the liquid component phase 16 merge in contact with the stripper to the point of forming droplets more important, which, by gravity, fall at the foot of the column 13.
• the column 13 is vertical, and the mixture 14 is introduced at the bottom of the column 13.
• the mixture 14 moves along the stripper in an upward movement, until the gaseous phase of solvent 18, freed of liquid phase, is recovered at the top of column 13.
• a countercurrent of a liquid phase 32 for rinsing is applied to the upward movement of the mixture 14 in the column.
• the liquid rinsing phase 32 improves the separation of the liquid component phase 16 from the mixture 14.
• the rinsing liquid phase 32 which has a movement contrary to the movement of the mixture 14 fixes the liquid component phase 16.
• the liquid phase droplets of component 16 merge with the rinsing liquid. More particularly, the rinsing liquid phase 32 flows along the stripper 12, causing in its movement the component liquid phase droplets 16 already attached to the mist separator 12.
• the flow of rinsing liquid 32 against the current of the mixture 14 also promotes the separation of the liquid phase droplets of component 16 still in the mixture with the solvent gas phase.
• the liquid rinsing phase 32 and the liquid component phase 16 are then recovered at the bottom of the column 13.
• the rinsing liquid phase 32 is a condensed solvent part.
• the solvent in the form of a gaseous phase is partially condensed and, by gravitation, the condensed liquid solvent entrains in its downward movement the component liquid phase 16 of the mixture. The portion of the uncondensed solvent is removed. The uncondensed solvent portion is component free and thus can be recycled.
• a liquid phase containing condensed solvent and the component is collected; this liquid phase is evaporated so as to separate the solvent component. This last evaporation step is simple to implement.
• the solvent is, for example, concentrated in the following manner.
• a temperature gradient is applied to the stripper 12, an area of the stripper 12 thus being colder; the mixture 14 is circulated in this cold zone, which allows the condensation of a part of the solvent gas phase.
• the partial condensation of the gaseous phase is obtained even within the column 13, which simplifies this operation.
• other part of the gaseous phase is not condensed and is evacuated.
• the upper end of the mist separator 12 is a cooler zone than the warmer lower end.
• an exchanger 34 traversed by a cold fluid is disposed at the top of column 13; a heating coating 36 may be arranged at the lower end of the column 13.
• the mixture 14 is injected at the warmer end of the mist separator 12, close to the coating 36.
• Part 32 of condensed solvent flows down the column and enters countercurrent contact with the gaseous phase solvent and component liquid phase mixture and acts as a rinsing agent, the condensed solvent part 32 is again vaporized by the coating 36, which avoids the filling and saturation of the device in the liquid phase is obtained better separation of the component and the solvent by an internal re-circulation of the solvent, this re-circulation is achieved without the use of external solvent pumping system, which is simpler and less expensive.
• the performances are regulated by the regulation of the temperature gradient
• Column 13 of FIG. 4 is a module which can be connected to the cyclonic chamber 20
• An advantage of the module and the process of FIG. 4 is their flexibility. Whatever the type of solvent or eluent, for example of the pure carbon dioxide type or with the addition of co-solvent, can be separated and recycled with the same module.
• the column 13 may be associated with each of the withdrawal lines of the fractions of a chromatography apparatus to ensure optimum yield of the isolated fractions during a chromatography step, this makes it possible to avoid the Column 13 mixture of the component of each fraction obtained from the chromatography column 13 can also be associated with a withdrawal line of a fraction having a particular interest, the other withdrawal lines can be associated with a single other column 13
• a cyclonic chamber can then be arranged per fraction withdrawal line, each of the chambers being connected to a demister; this improves the separation of the mixture 14 while avoiding the mixing of the components of each fraction resulting from the chromatography.
• all the cyclonic chambers of all the withdrawal lines are connected to a single stripper, which reduces the manufacturing costs of the device 10, and thus reduces the separation costs of the mixture resulting from the separation by chromatography.
• the invention also relates to a chromatography apparatus.
• the apparatus comprises a central separation unit 8 on a chromatographic bed, a supercritical or subcritical solvent being used, at least one fraction withdrawal line deriving from the central unit. Fraction 11 contains the supercritical or subcritical solvent and the component that it is desired to obtain following chromatography.
• the apparatus also comprises the device 10 as described above.
• the apparatus may also include a cyclonic chamber and a stripper by withdrawal line, the chamber being between the expander and the stripper. It can also be envisaged that a cyclonic chamber equip each line of withdrawal, and only one mistletoe successively collects the mixture of each chamber to separate it. This makes the chromatography apparatus less expensive.
• a first set consisting of cyclones in series, a second compound of a cyclone and a mistletoe in series.
• a liquid-gas mixture enters the first cyclone.
• the first cyclone vents are routed into the second cyclone, while the collected fluid is drained periodically.
• the vents of the second cyclone are routed into the third cyclone, while the collected liquid is drained at the end of the experiment.
• Second assembly Assembly according to one embodiment of the invention:
• a liquid-gas mixture enters a cyclone.
• the cyclone vents are routed into the mist separator, while the collected liquid is drained permanently.
• the liquid collected in the mist separator is drained periodically.

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• 2006
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