FR2912931A1 - Heavy molecules and/or particles e.g. carbon dioxide, separating device, for use in water filter, has collection channels collecting flow containing heavy and light particles, where pressure at inlet of channels is adjusted to be equal - Google Patents

Abstract

The device has a coil pipe (1) in which a fluid containing heavy and light molecules and/or particles (3b, 3a) is introduced under pressure to subject the fluid to a forced path to achieve rotational speeds. The particles and/or molecules (3b) are migrated towards a wall of large radius in the pipe for achieving a desired concentration. The pipe is divided into two collection channels (1b, 1a) configured for collecting a flow containing the molecules and/or the particles (3b, 3a), respectively, where a pressure at inlet of the channels is adjusted to be equal.

Description

1 Description The subject of the invention is a device for separating

  molecules and / or particles dispersed in a fluid.

  It relates to the technical field of the separation of molecules and / or particles dispersed in a fluid, by a helical setting of said fluid. It relates more particularly to devices intended for the separation of chemical or gaseous compounds, to the preparation of products enriched in concentration relative to their initial concentration, to the separation of elements contained in liquid or gaseous mixtures among which may be mentioned, without this being limiting: - systems for the preparation of pure gas from atmospheric air (noble gases, hydrogen, CO2 for example), - ambient air filtration systems (workshops, clean rooms, tertiary premises , hospitals, establishments open to the public, combustion air supply for combustion engines, ...), - gas filtration systems (chemical installations, exhaust gases from combustion engines and fireplaces, turbine feed gas, emissions from industrial chimneys, ...), - recovery and sorting systems according to aerodynamic sizes of particles in suspension for recovery (cement plants, sugar factories, semolina mills, grain mills, ...), - water filters for hydraulic installations (domestic, swimming pools, submerged pumps, drinking water supply, ...), - liquid filters (installations chemical, lubricating oil for engines and turbines, food industry, fruit juices, wines, dairy products, etc.),

  systems for recovering particles suspended in a liquid (preparatory chemistry, biology and microbiology, food industry, etc.), gaseous component concentration systems in an isotope of this component (uranium for example, ... ), enrichment systems at the concentration of a liquid component contained in a mixture (biology, pharmacy, chemistry, etc.).

  Document EP-B1-1,311,335 of the same inventor discloses a device for partial or total separation or for enriching the concentration of one or more components contained in a mixture of gaseous or liquid components, applicable to equipment for the removal or recovery of particles suspended in a gas or liquid. According to the device described, a fluid containing several kinds of molecules and / or particles is introduced by the effect of a pressure in a multi-turn helical duct so as to subject it to a forced trajectory making it possible to reach very high speeds. rotation of up to several millions of revolutions per second.

  The molecules and / or particles contained in the fluid undergo a centrifugal force proportional to the waste of each molecule and / or particle and to the square of the speed of rotation. If the molecules and / or particles have masses even slightly different from each other, they will experience different centrifugal forces and will move relative to each other with a speed proportional to their mass difference multiplied by the square of the rotation speed. This speed is, however, limited by the braking force caused by the molecules and / or particles of the fluid of greater concentration on the molecules and / or particles of the fluid that move relative to it. This braking force is described by the Fick-Einstein equation in fluid kinetics for molecules and by Stokes Cunningham's law for particles and a limit velocity is reached when the centrifugal force applied to the molecule and / or particle that moves becomes equal to the force 2912931 -3

  for the molecules, the Boltzmann constant, the absolute temperature of the fluid and the diffusion coefficient of the molecule which moves with respect to the fluid of higher concentration and for the particles, the diameter of the particle, the Cunningham coefficient and the kinematic viscosity of the carrier gas. The resultant Brownian motion, for the molecules, is always zero, it intervenes only in the definition of the diffusion coefficient, but not on the general trajectory of the molecule and / or particle that moves.

  There is therefore a separation of the molecules and / or particles according to their mass, the heavier ones being transported towards the wall of larger radius while chasing the molecules and / or the lightest particles which were there at the moment zero, the latter regrouping in the other part of the helical duct. Once this separation is made in the conduit, it is necessary to be able to collect the different fractions of the fluid for the device to have a real utility. In EP-B1-1,311,335, this extraction is carried out by means of outlet orifices placed on the wall of larger diameter of the helical conduit and each connected to a collection device. The fluid fraction at the largest radius wall at this point is withdrawn through each orifice at a fixed rate. The rate of withdrawal is controlled by means of a flow regulator so as to allow the passage of only a flow rate equal to the flow rate previously calculated at this point of the molecules and / or particles of one of the selected components of the mixture, to a concentration also chosen. In practice, it appears that this method is applicable only in the case where the dimensions of the spiral duct are large enough that the undersizing flow is compatible with what technology can do in this area. This can only concern devices in which one seeks, when working in molecular separation, an enrichment of a few percent, but by no means devices whose objective is an important enrichment, because for the latter the dimensions of each 2912931 -4

  spiral duct must be very small and therefore the flow rate of each duct very low and existing constant flow underflow systems can not ensure the necessary accuracy.

  US Pat. No. 2,360,066 (LOUMIET ET LAVIGNE) also discloses a similar device in which the extraction is carried out by several tubes arranged tangentially to the wall of maximum radius of the helical duct. The extraction is caused by depression of the extraction tubes relative to the main helical conduit. This depression necessarily implies that a portion of the carrier fluid is entrained in the extraction tubes which has the effect of limiting the quality of the molecular separation or the loss of carrier gas in particulate separation. This phenomenon is found elsewhere in the device described in EP-B1-1,311,335.

  In view of the state of the art, the main technical problem which the invention aims to solve is to increase the performance of the separation device of the type described in EP-B1-1.311.335, in particular the improvement of the quality of molecular and / or particulate separation and the extension of its application at very low concentrations of the liquid or gaseous components to be separated from the higher concentration fluid. Another object of the invention is to be able to extract the different fractions of the fluid, in a simple manner and without the use of ancillary flow control devices. It is another object of the invention to provide a separating device which is simple in design, easy to handle and inexpensive.

  The solution proposed by the invention is a device for separating molecules and / or particles contained in a fluid, said device comprising a multi-turn helical conduit in which a fluid containing several kinds of molecules and / or particles is introduced under pressure so as to subject said fluid to a forced trajectory making it possible to reach

  sufficient rotational speeds, said molecules and / or particles being separated according to their mass under the effect of the centrifugal force. This device is remarkable in that at the location of the helical duct where the molecules and / or heavier particles have sufficiently migrated to the wall of larger radius to achieve a desired concentration, said helical duct is divided into two channels of extraction, a first channel configured to recover a stream containing said molecules and / or heavier particles and a second channel configured to recover a stream containing the other molecules and / or lighter particles, the pressure at the entrance of the two said channels being adjusted to be equal. This extraction technique is much more effective than the known technique of the prior art of sucking a portion of the flow at the wall of greater radius. Indeed, at the level of the division of the helical duct, no parasite effect disturbs the distribution of molecules and / or particles, which makes it possible to effectively recover the latter even at very low concentrations.

  Other advantages and characteristics of the invention will appear better on reading the description of a preferred embodiment which follows, with reference to the accompanying drawings, made by way of indicative and non-limiting examples and in which: FIG. 1 is a schematic view in longitudinal section of the device according to the invention according to a first embodiment, showing at each turn the migration of the molecules and / or particles; FIG. 2 is a sectional view along AA of FIG. FIG. 3 is a diagrammatic longitudinal sectional view of a helical conduit according to a second embodiment, showing at each turn the migration of the molecules and / or particles, the system for separating the molecules and or particles not shown,

  FIG. 4 schematically represents the helical duct of FIG. 3 in the unwound state, said duct being arranged with the system for separating the molecules and / or particles; FIGS. 5a, 5b and 5c schematize different profiles of helical duct with molecules and / or particles at the level of the wall of minimum radius; FIGS. 6a, 6b and 6c schematize the different helical channel profiles of FIGS. 5a, 5b and 5c with molecules and / or particles at the level of the wall of maximum radius, - Figures 7a, 7b and 7c schematize different profiles of the drawing surface according to the different spiral duct profiles schematized in Figures 5a, 5b and 5c, - Figures 8a, 8b, 8c and 8c schematically different surface profiles of drawing for a square or rectangular profile of the helical duct, - Figure 9 shows a drawing surface profile for a circular profile of the helical duct.

  In the same manner as described in document E-BI-1.311.335, the device that is the subject of the invention is formed of a helical conduit comprising a plurality of turns. A fluid, liquid or gaseous, containing several kinds of molecules and / or particles is introduced under pressure into the helical conduit via a pump-type injector or any other equivalent means suitable for those skilled in the art.

  Referring to the first embodiment shown in FIG. 1, the multi-turn helical duct 1 is preferably formed by a pitch-threaded mandrel 10, arranged in a tube 11. In an alternative embodiment shown in FIG. helical 1 may be formed by a capillary tube 12 of circular, square, rectangular, triangular or other general profile, and wound around a mandrel 13.

  Referring to Figure 1, the fluid containing several kinds of molecules and / or particles 3a, 3b, is introduced under pressure (shown schematically by the arrow) in the helical duct 1. Following the turns of the helical duct 1, the fluid is rotated and the molecules and / or particles 3a, 3b undergo a centrifugal force proportional to their mass and the square of their rotational speed. As shown in Figure 1, after a number of turns, there is a separation of molecules and / or particles according to their mass. The heavier molecules and / or particles 3b are transported to the wall of maximum radius and the molecules and / or lighter particles 3a gathering in the other part of the helical conduit. As the flow of fluid in the helical duct 1, the distribution of particles will stratify according to the radius of said duct.

  The fluid is introduced into the helical duct 1 at the pressure necessary to obtain the desired speed of rotation. The pressure to be applied to the fluid to circulate it at high speed is proportional to the pressure drop of the helical duct 1 and therefore to the number of turns constituting the latter. It is therefore of interest that the number of turns necessary for the desired separation be as small as possible.

  This number of turns is defined, if one wants a complete separation between the two phases, by the time necessary for the molecules and / or particles to be separated (to eliminate them or to recover them) most unfavorably placed in the helical conduit at the time of their introduction (that is, those introduced at the level of the minimum radius wall) to travel the distance separating them from the wall of maximum radius. This time is equal to the distance between the two opposite walls of the helical duct 1, in the direction of the radius of the helicoid, divided by the relative radial velocity of the molecule and / or particle relative to the molecules and / or particles of the fluid of higher concentration. The longer this time is, the more the molecule and / or particle to be separated will have to travel in turns to reach the wall of maximum radius and therefore the charge losses will increase. It can be noted that it is possible to limit the

  separation at a concentration less than 100% by limiting, accordingly, the number of turns and to resume this concentration by a second or third third separation stage. It is therefore appropriate to optimize the dimensions and the geometry of the helical duct 1 so that this time is minimum and, at the same time, the number of molecules and / or particles passing from the wall of minimum radius to the wall of maximum radius, ie maximum.

  These improvement requirements lead to the following conclusions for sizing the helical duct 1: The centrifugal force, therefore the relative radial velocity of the molecule and / or particle to be separated, is inversely proportional to the rotation radius of the molecule and / or particle. this radius, therefore the inner radius of the helicoid, must be as small as possible. 15 -> The number of turns necessary for the separation being proportional to the distance between the two opposite walls of the helical duct 1, according to the radius of the helicoid, this distance, therefore the outer radius of the helicoid, must be the most small possible.

  The fixing of these dimensions is, however, limited by the technological requirements and the desired capacity of the device. They are therefore defined on a case-by-case basis, by a compromise between the desired performances in terms of device throughput and the technological constraints (maximum available pressure, overall dimensions of the installation composed of several unitary separation devices mounted in parallel and / or or in series, ...).

  After having defined the optimum distance between the walls of the helical duct 1, according to the radius of the helicoid, it is necessary to define the best geometry, that is to say the best overall profile of said duct. Several profiles are possible and in particular the profiles:

  - circular (Figures 5c and 6c). For example: capillary tube with a circular profile wrapped around a central mandrel; - triangular (Figures 5b and 6b). For example: threaded mandrel with triangular thread, capillary tube with triangular profile wrapped around a central mandrel; -rectangular or square (Figures 1, 5a and 6a). For example: threaded mandrel 10 with rectangular or square thread, rectangular or square shaped capillary tube wrapped around a central mandrel.

  Referring to Figures 5a, 5b, 5c, 6a, 6b and 6c, it appears that the square or rectangular profiles are more efficient than the others. Indeed, for the same transfer time between the two walls of the helical duct 1, the number of molecules and / or particles to be separated 3b transferred from one wall 10a to the other 10b is greater for a square or rectangular profile. only for a triangular or circular profile !. As shown in FIGS. 5a, 5b and 5c, in which the diameter of the circular duct is equal to the height of the triangle of the triangular duct and to the side of the rectangular duct, and where the radial velocities of the molecules and / or particles to be separated 3b are equal, the number of molecules and / or particles arranged on the point farthest from the wall of maximum radius 10b is equal to 1 with respect to the circular and triangular profiles and n 1 with respect to the square or rectangular profile . This means that for the same time, so for a number of equal turns, in a circular or triangular profile the number of molecules and / or particles to be separated 3b transferred from the wall of minimum radius 10a to the wall of maximum radius 10b is n times smaller than in the case of a square or rectangular profile. This advantage is not limited to the molecules and / or particles introduced at the level of the minimum radius wall 10a but to all the molecules and / or particles, since the concentration transfer to the wall of maximum radius 10b is represented by the flow of molecules and / or animated particles - 10-

  their limit speed at said wall of maximum radius. This flow is equal to the velocity of the molecules and / or particles by the passing surface at the point 'P' along the height 'h' of the helical duct 1. The passing surface at the point 'P' is equal to the width of the helical duct 1 multiplied by the length of said duct (number of turns multiplied by length of a turn). It is found that the passage area at point 'P' is constant for a square or rectangular profile. For a circular profile, the passage area at the 'P' point varies from zero to the diameter of the helical duct 1 multiplied by the length of said duct. And for a triangular profile, the passage area at the point P varies from zero to the base of the triangle multiplied by the length of the helical duct 1. This advantage of the square or rectangular profile appears in FIGS. 6a, 6b and 6c for ducts of FIG. identical height with identical initial concentration. The surfaces being different depending on the geometry, the number of molecules and / or particles to be separated 3b brought to the level of the wall of maximum radius 10b after a path of equal length varies by a coefficient 1 for the square or rectangular profile, at 0.785 for the circular profile and at 0.5 for the triangular profile.

  The differential centrifugal force acting on the molecules and / or particles to be separated 3b is proportional to the square of the velocity of the fluid in the helical duct 1. The greater this speed, the faster the separation and therefore the number of turns. needed for separation is small. The limitation of the number of turns is not only interesting for the reduction of the dimensions of the device but also for the reduction of the pressure necessary to maintain the desired speed of the fluid. This pressure is defined by the overall pressure drop of the helical duct 1 and is equal, to the effects of entry and exit, to the pressure drop of a turn multiplied by the number of turns. This overall pressure drop is therefore proportional to the number of turns needed (inversely proportional to the square of the 2912931 -11-

  fluid velocity) and the pressure drop of a coil (directly proportional to the square of the fluid velocity). These two factors having antinomic effects, the fluid regime must be taken into account. The pressure drop of the helical duct 1 depends on the flow velocity of the fluid, the dimensions of said duct and the flow regime which itself depends on the velocity of said fluid and the dimensions of said circuit. This flow regime may be laminar for a Reynolds number less than 2,000, transient for a Reynolds number between 2,000 and 4,000 or turbulent for a Reynolds number greater than 4,000. Generally, a transient or turbulent flow induces higher pressure losses than those induced by a laminar flow. Increasing the fluid velocity therefore reduces the dimensions of the helical duct 1 but does not automatically reduce the pressure, therefore the energy required for the operation of the device. The choice of the fluid velocity for a helical duct of given dimensions must take into account the nature of the flow for the general reasons invoked above, but also for reasons specific to the process.

  With reference to FIGS. 1 to 4, the separation technique that occurs in the helical conduit 1 is based on the displacement of the heavier molecules and / or particles 3b relative to other molecules and / or lighter particles 3a, under the effect of a differential centrifugal force. Since the differences in mass of the molecules and / or particles to be separated can be very small, the differential centrifugal force is very low and it is not to be risked to introduce parasitic forces into the helical duct which may be larger than this centrifugal force. This may be the case for a turbulent flow in which random vortex forces occur at certain points of the helical duct 1. In order to limit the quality of the separation, the effect of these random vortex forces must in no case cancel the effect of the centrifugal force before the extraction of the molecules and / or particles and return to the 2912931 -12-

  circuit a molecule and / or particle having reached the extraction device. It therefore appears that the velocity of the fluid in the helical duct 1 must be calculated so that the Reynolds number of said duct remains preferably less than or close to 2,000 and maintain a laminar flow in said duct. This does not exclude, for certain particular cases, adopting higher speeds by accepting a transient or turbulent flow regime, that is to say a Reynolds number greater than 2,000.

  According to a preferred feature of the invention shown in Figures 1, 2, 3 and 4, at the location of the helical conduit 1 where the molecules and / or heavier particles 3b have sufficiently migrated to the wall of larger radius to To achieve a desired concentration, said helical duct 1 is divided into two extraction channels: a first channel 1b configured to recover a stream containing the molecules and / or heavier particles 3b; and a second channel configured to recover a stream containing the other molecules and / or lighter particles 3a. The two channels 1a, 1b are connected to reception chambers, respectively 5a, 5b. As described below, to optimize separation and not to generate parasitic effects capable of disturbing the distribution of molecules and / or particles at the level of the separation of the helical conduit, the pressure at the inlet of the two extraction channels 1 a, lb is adjusted to be equal. The division of the helical duct 1 makes it possible to simply recover, and without the use of an auxiliary device for controlling the flow, at the desired concentration, the different fractions of the fluid.

  The molecules and / or heavier particles 3b may be those to be removed (for example: CO2 contained in atmospheric air or pollutant particles suspended in the air, etc.) or those to be recovered (for example: Radon or Xenon contained in atmospheric air, particles suspended in the air for recovery,

  .). One may even want to recover 2912931 -13 - .. DTD: the lighter molecules, for example: Hydrogen in the air or Hydrogen in CO2.

  The profile of the channel 1b for extracting the flow containing the molecules 5 and / or the heaviest particles 3b must be configured to optimize the separation. The extraction technique used in the invention makes use of the concept of a drawing surface (or channel) which becomes an important parameter in the design of the circuit. To define this new parameter, it is advantageous to introduce another parameter which is the initial concentration 'C' of the fraction of molecules and / or heaviest particles to be separated before the introduction of the fluid into the helical duct and the final concentration 'C' of these molecules and / or desired particles in the drawing surface.

  It is possible to divide the helical duct using tangential extraction tubes of the type described in Figures 4, 5 and 6 of US 2,360,066 (LOUMIET AND LAVIGNE). However, according to a preferred feature of the invention for optimizing the grouping of molecules and / or heavier particles and to make their extraction easier, the helical duct advantageously comprises a drawing surface at its maximum radius wall. . With reference to the appended figures, the concept of a drawing surface is defined as follows: instead of bringing the heavier molecules and / or particles 3b to the maximum radius wall of a symmetrical helical duct 1 (see EP). -B1-1.311.335), a drawing surface 110 in which the molecules and / or heavier particles 3b, transported under the structure, is created throughout the turns at the level of said wall of maximum radius. effect of the centrifugal force, by driving out the other molecules and / or lighter particles 3a of the fluid that were there at time zero.

  The sizing of this drawing surface 110 conditions the quality of the separation and the final concentration that will be obtained therein:

  if the flow rate of the fluid in this drawing surface 110 (surface x fluid velocity) is greater than the total possible flow rate of the molecules and / or heavier particles 3b to be extracted (total flow of the fluid in the helical duct multiplied by the initial concentration of molecules and / or particles to be extracted), the final concentration will never reach 100% because the other molecules and / or lighter particles 3a of the vector fluid will complete said molecules and / or heavier particles 3b of the fraction of fluid to be extracted. which are not numerous enough in the helical duct 1 to fill the drawing surface 110. - + If the flow rate of the fluid in this drawing surface 110 is less than the total possible flow rate of the molecules and / or heavier particles 3b to be extracted, the concentration in said drawing surface will be equal to 100%, but a part of said molecules and / or larger particles 3b to be extracted present in the con helical duit 1 have not been able to enter said drawing surface and will be rejected with the other molecules and / or lighter particles 3a of the vector fluid. If the flow rate of the fluid in this drawing surface 110 is equal to the possible total flow rate of the molecules and / or heavier particles 3b to be extracted, said drawing surface will be filled only with the molecules and / or heavier particles 3b to be extracted, the concentration will be 100% there, no other molecule and / or lighter particle 3a of the vector fluid will be in this surface and no molecule and / or heavier particle 3b to be extracted will be outside this surface. This extraction technique therefore makes it possible to choose the final concentration of the molecules and / or particles to be extracted between zero and 100% by choosing the dimensions of the drawing surface.

  If we take again the various general profiles of the helical duct 1 represented in FIGS. 5a, 5b, 5c, 6a, 6b and 6d, the optimal geometries 30 of the drawing surfaces 110 of each configuration appear in FIGS. 7a, 7b and 7c. The higher the height of this drawing surface 110 is 2912931 -15-

  the greater the separation of the streams is technologically easy and the better the separation accuracy. If we eliminate the helical duct with triangular general profile which seems to be of limited interest, it appears that the thicknesses of the drawing surfaces 110 of a helical duct 1 with a generally square or rectangular profile and with a generally circular profile are substantially identical. The profile of the drawing surface 110 must be defined in such a way that the molecules and / or heavier particles 3b to be extracted can be easily collected at the desired concentration, which is automatically the case for a circular profile. With regard to a helical duct with a generally square or rectangular profile, the heavier molecules and / or particles 3b must be able to be transported under the effect of the centrifugal force. Preferably, a drawing surface 110 having one of the geometries indicated in FIGS. 8a, 8b and 8c is used: square or rectangular profile, semicircular profile, triangular profile. This latter profile is also that shown in FIG. 1. The optimal geometry appears to be that represented in FIG. 8d, that is to say a drawing surface 110 whose profile has the shape of an inverted `V`, 20 having a broad base and a rapidly narrow elongate end. However, any other geometry that does not interfere with the transport of the molecules and / or particles towards the drawing surface 110 can be used by those skilled in the art.

  With regard to a spiral duct 1 with a generally circular profile, it is possible to provide a moon-shaped drawing surface 110 of the type shown in FIG. 9.

  To increase the height of the drawing surface 110 when the duct is generally circular in shape, a duct having

  drop-shaped profile as shown in the figures of US 2,360,066 (LOUMIET AND LAVIGNE).

  It is also possible to imagine a means for increasing the height of the drawing surface for a helical duct with a generally square or rectangular profile. Referring to Figure 1, when the helical duct 1 is formed by the combination of the threaded mandrel 10 and the tube 11, the latter advantageously comprises a tapping at the same pitch as that of the thread of said mandrel. The tapping geometry of the tube 11 defines the profile of the tapping surface 110. Referring to FIG. 3, it is still possible to use a capillary tube 12 wound around a mandrel 13, said capillary tube having the profile general desired for the helical duct and integrating the profile of the drawing surface 110. Referring to the embodiment shown in Figure 3, the helical duct 1 has a general square or rectangular profile which is superimposed a triangular profile forming the drawing surface 110. However, this embodiment is not limiting, the capillary tube 12 may have any other desired profile and in particular those shown in Figures 8a to 8d and in Figure 9.

  The presence of this drawing surface 110 makes the extraction of the stream containing the molecules and / or heavier particles 3b to be separated very simply, via the first recovery channel 1b. In order to optimize the recovery of the flow containing the molecules and / or heavier particles 3b, the first channel 1b has the same profile as that of the drawing surface 110. The flow containing the other molecules and / or lighter particles 3a unable to reach the drawing surface 110 is discharged via the second channel la. These molecules and / or particles 3a, 3b are then recovered in reception chambers, respectively 5a, 5b. 2912931 -17-

  The division of the spiral duct depends on the design of the latter. It can be achieved by arranging at the level of the wall of greater radius, a tangential tube of the type described in Figures 4, 5 and 6 of US 2,360,066 (LOUMIET AND LAVIGNE). However, with reference to the appended FIGS. 2 and 4, it is preferable to introduce, at the level of the outlet of the helical conduit 1, an insert 4 configured so as to separate, without turbulence, the flow in two parts and to send each of these parts in extraction channels 1a, 1b. In practice, the geometry of the insert 4 is adapted to the geometry of the helical duct 1 and the geometry of the drawing surface 110 so as to separate, without turbulence, the flow in two parts.

  When the helical duct 1 is formed by the combination of the threaded mandrel 10 and the tube 11 (FIGS. 1 and 2), the insert 4 is disposed substantially at the outlet of said helical duct, against the wall of minimum radius. Its height is limited to the height of the thread of the mandrel 10 so that it does not come to obstruct the drawing surface 110. The height of the insert 4 will be equal to the height of the thread of the mandrel 10 if it is desired to concentration 100% or less than this height if a final concentration of less than 100% is desired The first channel 1b tangentially connects the drawing surface 110 at the level of the insert 4. The latter is configured so as not to disturb the stream containing the molecules and / or heavier particles 3b discharged by the first channel lb to the receiving chamber 5b (Figure 2). The threaded mandrel 10 has a bore forming the second recovery channel 1a. The latter communicates with the helical duct 1 via an orifice 100 disposed at the level of the wall of minimum radius and in front of the insert 4. The second recovery channel 1a is connected to the receiving chamber 5a. The insert 4 is configured to deflect towards the orifice 100 and the second recovery channel 1a, without causing turbulence, the flow containing the particles 2912931 -18-

  molecules and / or lighter particles 3a, not present in the drawing surface 110.

  Referring to Figures 3 and 4, the use of the insert 4 is also suitable for the case where the helical duct 1 is formed by a capillary tube 12 wound around a mandrel 13. As previously described, the insert 4 is disposed substantially at the outlet of the helical duct 1, against the wall of minimum radius. Its height is determined so as to leave free the drawing surface 110 if a concentration of 100% or a larger area is desired if a concentration of less than 100% is accepted. The positioning of the insert 4 in the helical duct 1 forms, downstream of the latter, the first channel 1b. The latter is thus arranged tangentially to the drawing surface 110. The insert 4 is configured so as not to disturb the flow containing the molecules and / or more heavy particles 3b evacuated by the first channel 1b towards the reception chamber 5b. The helical conduit 1 communicates with the second channel via an orifice 101 disposed at the minimum radius wall and in front of the insert 4. The second recovery channel is connected to the receiving chamber 5a. The insert 4 is configured to deflect, without causing turbulence, the stream containing the lighter molecules and / or particles 3a to the port 101 and the second recovery channel 1a.

  According to a preferred feature of the invention allowing for optimal separation, it is necessary to avoid disturbing the flow at the time of the division of the flow. It is therefore important, at the time of the separation, that the two fractions of separated fluids (that contained in the extraction surface and that contained in the other part of the helical duct) see before them equivalent flow conditions. If the pressures are not balanced, the separation can not be optimal. Indeed, in the case where the first channel 1b is in depression with respect to the second channel 1a, a part of the lighter molecules and / or particles 3a which were not present in FIG.

  the drawing surface 110 could be driven into said first channel 1b. The quality of the separation would in this case be impaired. Similarly, in the case where the first channel 1b is in excess pressure with respect to the second channel 1a, part of the heavier molecules and / or particles 3b that were present in the drawing surface 110 could be entrained in said second channel. the. To solve this problem, the pressure in both channels 1a and 1b is adjusted to be equal. In practice, there is used for each receiving chamber 5a, 5b, a pressure controller and a flow controller or overflow or other pressure equalizer 50a, 50b. As soon as the pressures are no longer equal, part of the fluid contained in the receiving chamber having the highest pressure is discharged so as to restore the equilibrium of the pressures.

  Depending on the fluid flow rate to be treated, an installation 15 may be provided comprising a plurality of separation devices arranged in parallel.

  It is also possible to provide a system for purifying or purifying a fluid formed by different separation devices arranged in series so as to form different purification or purification stages. Indeed, the fluid can be separated in several times to extract other molecules and / or particles that would not have been in a first stage because of their masses too close or because of their low concentration. In this case, these molecules and / or particles are separated in a second stage by re-injecting the extracted stream from the first stage (at higher concentration) into another similar separation device. This operation can be carried out as many times as necessary to obtain the desired degree of purification or purity. In practice, the extraction channels 1a and / or 1b or the receiving chambers 5a and / or 5b are connected to other similar helical conduits.

Claims (14)

claims   1. Device for separating molecules and / or particles contained in a fluid, said device comprising multi-turn helical conduit (1) in which a fluid containing several kinds of molecules and / or particles (3a, 3b) is introduced under pressure so as to subject said fluid to a forced path for achieving sufficient rotational speeds, said molecules and / or particles being separated according to their mass under the effect of the centrifugal force, characterized by the fact that at the where the heavier molecules and / or particles (3b) have sufficiently migrated to the wall of larger radius to reach a desired concentration in the helical duct (1), said helical duct (1) is divided into two extraction channels, a first channel (1b) configured to recover a stream containing said molecules and / or heavier particles (3b) and a second channel (1a) configured to recover a contained stream the other molecules and / or lighter particles (3a), the inlet pressure both said channels being adjusted to be equal.   2. Device according to claim 1, wherein an insert (4) is introduced at the output of the helical duct (1), said insert being configured to separate, without turbulence, the flow in two parts and send each of these parts in the extraction channels (la, lb).   3. Device according to one of the preceding claims, wherein the helical duct (1) comprises a drawing surface (110) at its wall of maximum radius, said drawing surface 2912931 - 21 - being configured so that that the molecules and / or heavier particles (3b) concentrate there under the effect of the centrifugal force.   4. Device according to claim 3 wherein the drawing surface (110) has a square, rectangular, semicircular or triangular profile.   The device of claim 3, wherein the drawing surface (110) has a profile in the form of an inverted 'V' having a broad base and a rapidly narrow elongated end.   6. Device according to one of claims 3 to 5, wherein the first channel (1b) has the same profile as that of the drawing surface (110). 15   7. Device according to one of claims 3 to 5 taken in combination with claim 2, wherein the insert (4) is configured so as not to disturb the flow containing the molecules and / or heavier particles (3b) contained in the drawing surface (110) and discharged through the first channel (1b) and so as not to disturb the flow containing the other molecules and / or lighter particles (3a) contained in the other part of the helical duct (1) and evacuated by the second channel (la). 25   8. Device according to one of the preceding claims, wherein the helical duct (1) is formed by a capillary tube (12) wound around a mandrel (13).   9. Device according to one of claims 1 to 7, wherein the helical duct (1) is formed by the combination of a mandrel (10) threaded and a tube (11) surrounding said mandrel. 22 -   10. Device according to claim 9 taken in combination with one of claims 3 to 7, wherein the tube (11) comprises a tapping at the same pitch as that of the thread of the mandrel (10), the geometry of said tapping forming the profile the drawing surface (110).   11. Device according to one of the preceding claims, wherein the helical duct (1) has a general circular or triangular profile.   12. Device according to one of claims 1 to 10, wherein the helical duct (1) has a rectangular or square general profile.   13. System for purifying or purifying a fluid, characterized in that it is formed by different separation devices according to the preceding claims, said devices being arranged in series so as to form different stages of purification or purification.   14. Installation for separating molecules and / or particles contained in a fluid, characterized in that it comprises a plurality of separation devices according to the preceding claims arranged in parallel. 20