EP0323929A1 - Static homogenising device for a circulating fluid - Google Patents

Abstract

A liquid to be homogenized successively passes through two perforated walls (TA, TB), forming jets (F2, F6) at each crossing which effect mixing. These two walls extend longitudinally opposite the same section of the axis (A) of the device. The liquid passes from one to the other following a circumferential path (F4) and its longitudinal flow direction is locally reversed (F5). The invention applies in particular to the measurement of the content of a mixture in one of these constituents.

Description

The present invention relates to the homogenization of a fluid, for example a liquid circulating in a pipeline. It applies in particular when this liquid comprises two immiscible phases. A device according to the invention is intended for example to homogenize a mixture of petroleum and water circulating in a horizontal transport pipe to allow a correct measurement of the water content of this mixture.

Such a measurement is in fact usually done on samples taken periodically and automatically in the pipeline, and, so that the measurement carried out on the samples represents the composition of the entire batch of fluid, it is first necessary that this batch is homogeneous. However, the components of such a mixture tend to separate naturally at least when its circulation speed is small, for example less than 1 m / s. A homogenization device must therefore intervene a little upstream from the point where the samples are taken.

Homogenization can also be useful in the following cases:
- when a pipeline carries a multiphase fluid whose phases tend to separate (due to gravity for example) and that this separation causes discomfort to operation, abnormal wear or corrosion of the pipes.
- upstream of the connection point of a secondary pipe supplying a user of the transported fluid, this so that this user receives a product whose two phases are in the right proportions,
- when you want to mix online, for the purpose of manufacturing a product, two liquid constituents.

Among the various situations in which homogenization is useful, the present invention relates to those in which the energy used by the homogenization device is taken from the fluid to be homogenized itself. The latter then undergoes a pressure drop when crossing this device. Such a device is said to be static if it does not have moving parts, which simplifies its production.

A static homogenization device is known from patent document EP-A-0064137 (Alsthom) and its correspondent US-A-4 408 892.

It has various arrangements which are common, at least to some extent, to this known device and to the device according to the present invention, and which will be explained first. These common provisions are as follows:

The device includes:
- An inlet having an axis and a diameter for receiving an inlet flow of said fluid along said axis from an upstream side of this device;
- An outlet having the same axis and the same diameter to restore an outlet flow of said fluid along said axis on a downstream side of this device, this axis being a device axis and having a longitudinal direction perpendicular to transverse directions which are in particular radial and circumferential directions, this diameter being that of a reference surface which is cylindrical and coaxial with this device,
- And mixing chambers connected between this inlet and this outlet and each comprising a feed compartment, and a stirring compartment separated by a perforated wall for receiving nets from said stream in this feed compartment and for forming a plurality thereof jets which are perpendicular to this wall and which penetrate into this stirring compartment in order to stir said fluid therein, this wall having a longitudinal extent and an extent in a first said transverse direction in order to present a large area in a radially limited space, of so that these jets have velocity components in a second so-called transverse direction perpendicular to the first, these supply and stirring compartments being further delimited by inlet and outlet guide walls which leave an inlet for this chamber in this feed compartment and an outlet from this chamber in this compartment t of mixing, these guide walls having an extension opposite said wall perforated so as to give said flow a direction substantially parallel to this perforated wall in each of these compartments with curvature of said threads on either side of this perforated wall,
said perforated walls being at least partially contained in said reference surface and longitudinally coextensive so as to limit the longitudinal and radial size of the device,
- Said mixing chambers being offset transversely with respect to one another in a transverse offset direction.

In this known device, the axis being assumed to be horizontal, two supply compartments and two planar, almost horizontal perforated walls (see FIGS. 2 and 6) feed a patch compartment interposed and partitioned by transverse internal partitions. Within this compartment, said jets penetrate almost vertically, and are curved laterally at a right angle. The liquid fillets resume the direct longitudinal direction by a second curvature at a right angle in the vicinity of the cylindrical outer envelope.

The two perforated plates are arranged symmetrically on either side of a horizontal axial plane and are therefore longitudinally coextensive. They trap said partitioned brewing compartment therebetween. It can be considered that they form with the external envelope two mixing chambers which are symmetrical with respect to the horizontal axial plane and whose mixing compartments are located on either side of this plane without a partition wall. It then appears that these two symmetrical chambers are traversed in parallel by two halves of the liquid flow.

The main purpose of this known device is to obtain an emulsification, that is to say a reduction in the diameter of the drops of the dispersed phase, their final diameter being a function of the pressure drop in the device. The homogenization function is also present, both inside and immediately downstream of the device. But it is not always filled with such high efficiency and / or such a small pressure drop as we would like.

The object of the present invention is in particular to obtain good homogenization, this within a simple and space-saving device, and by imposing only a very moderate pressure drop on the flow of the fluid to be homogenized.

It relates to a device presenting the common provisions previously stated. Compared to the known device previously described, the device according to the invention is characterized in that it includes transfer means for connecting the outlet of a first said mixing chamber to the inlet of a second said mixing chamber. so as to connect these two chambers in series by making them pass successively through the same thread of said stream.

According to the present invention, the following sometimes preferred arrangements can also be adopted:
- Said inlet and outlet guide walls give said flow a substantially longitudinal direction in each of said supply and stirring compartments of each said mixing chamber, these walls comprising a main guide wall facing said perforated wall and inclined with respect to this perforated wall so as to deviate therefrom towards said inlet and said outlet of said mixing chamber, respectively,
- said transfer means comprising at least one transfer chamber which has an extent in said offset direction (DC),
- Said device comprising a succession of inversion chambers in an even number on the path of each thread of said flow, each of these chambers reversing the longitudinal component of the average speed of the fraction of said flow which traverses it, at least one of these chambers inversion being constituted by said transfer chamber.
- Each of said transfer chambers extends from a single said upstream or downstream side of all of said mixing chambers, directly connects two of these chambers and constitutes a single said inversion chamber, so as to allow a simple realization of the device.

• La figure 1 représente une vue en coupe axiale du premier dispositif selon l'invention.
• La figure 2 représente une vue partielle en perspective du dispositif de la figure 1.
• La figure 3 représente une vue d'un deuxième dispositif selon l'invention, en coupe transversale selon une ligne III-III de la figure 4.
• La figure 4 représente une vue de même dispositif en coupe par une surface cylindrique de révolution autour l'axe A de ce dispositif, cette surface étant représentée par une ligne IV de la figure 3, cette surface de coupe étant supposée avoir été fendue selon une génératrice B représentée par un point sur la figure 3 et par deux droites sur la figure 4, cette surface de coupe étant supposée avoir été ensuite développée à plat pour constituer la figure 4.
• La figure 5 représente une vue d'un troisième dispositif selon l'invention en perspective avec arrachement partiel.
• La figure 6 représente une vue du même dispositif en coupe transversale selon une ligne VI-VI de la figure 5.

Using the attached schematic figures, we will describe more particularly below, by way of nonlimiting example, how the present invention can be implemented in the context of the description which was given above. When the same element is represented in several figures, it is designated therein by the same reference sign. Three devices according to three modes of implementation are given as an example. They include the sometimes preferred arrangements mentioned above. It should be understood that the elements mentioned may be replaced by other elements ensuring the same technical functions.

• Figure 1 shows an axial sectional view of the first device according to the invention.
• FIG. 2 represents a partial perspective view of the device of FIG. 1.
• FIG. 3 represents a view of a second device according to the invention, in cross section along a line III-III of FIG. 4.
• FIG. 4 represents a view of the same device in section through a cylindrical surface of revolution about the axis A of this device, this surface being represented by a line IV in FIG. 3, this cutting surface being supposed to have been split in a generator B represented by a point in FIG. 3 and by two straight lines in FIG. 4, this cutting surface being assumed to have then been developed flat to constitute FIG. 4.
• FIG. 5 represents a view of a third device according to the invention in perspective with partial cutaway.
• FIG. 6 represents a view of the same device in cross section along a line VI-VI of FIG. 5.

To simplify the description, the three devices according to the invention are assumed to have the same axis A which defines direct longitudinal directions LD and reverse LI and transverse directions such as the circumferential DC and radial directions DR.

A room will generally be designated below by the references of the walls which delimit this room. A part comprising several parts will be designated by the references of these parts.

The first and second devices according to the invention both have the following arrangement:
The number of said mixing chambers is two, these chambers being a first and a second chamber comprising a first and a second said perforated walls separating a first and a second said supply compartments from a first and a second said compartments stirring, the inlet of this first chamber and the outlet of this second chamber constituting the inlet and the outlet of said device, respectively, one of these two chambers being a so-called reversing chamber, the number of said transfer chambers being one on the path of each thread of said stream.

First of all generally, in the first device according to the invention, the two said perforated walls are formed in two angular sectors TA, TB of a tube TA, TB, TC, TD, TE coaxial with said device so that said first and second transverse directions are circumferential and radial, respectively. This tube has at its two ends two openings which constitute the inlet 2 and the outlet 4 of this device. An oblique separating wall 6 closes off the space inside this tube so that these two perforated walls face the two faces of this separating plate, respectively. Said first perforated plate TA and this separating plate 6 delimit said supply compartment TC, TA, TD, 6 from said first mixing chamber. Said second perforated plate TB and this same separating plate delimit said mixing compartment TC, TB, TD, 6 of said second mixing chamber. The perforations of the walls TA and TB are shown at 20.
The device further comprises a casing 8 having a longitudinal and circumferential extent and located radially beyond this tube, at least opposite the two said perforated plates, and two lateral guide walls PAC, PAD and PBC, PBD having longitudinal ranges and radial and located angularly on either side of each of the two said perforated plates, to constitute with said envelope 8 said mixing compartment TA, PAC, PAD, 8 of said first mixing chamber and said feed compartment TB, PBC, PBD, 8 of said second mixing chamber.
- Said tube extends into an additional non-perforated section TE on the side for example of the assembly of the two said mixing chambers. This section extends angularly in the two angular sectors of the two said perforated walls TA, TB and in at least one angular transfer sector TC, TD joining the two preceding ones. It extends longitudinally from an internal edge 10 on the side of said perforated walls to an external edge 12. Said casing 8 extends opposite this non-perforated section TE. The device also comprises a transverse external transfer wall 14 having a radial and circumferential extent and joining said external edge 12 of said non-perforated section to said casing 8 and at least one transverse internal transfer wall 16 having a radial and circumferential extent and joining said inner edge 10 of said non-perforated section TE to said casing 8 in said angular transfer sector, so that said non-perforated section, said casing facing this section and the two said transverse transfer walls constitute said transfer chamber TE, 8 , 14, 16, said DC offset direction being circumferential.

More particularly, this first device comprises two said angular transfer sectors TC, TD opposite forming a complete tube with the two angular sectors of the two said perforated walls TA, TB. Said casing 8 is a coaxial conical wall widening on the side of said non-perforated section TE by constituting two said transfer chambers TE, 14, 8, 16 and TE, 14, 8, 18 connected in parallel and comprising two said internal walls of transfer 16, 18, respectively, so as to produce a simple and symmetrical structure with respect to two perpendicular diametrical planes.

The two said transfer chambers are symmetrical to each other with respect to a vertical axial plane and the two said mixing chambers are symmetrical to each other with respect to a horizontal axial plane.

Successive liquid threads, that is to say successive sections of the path of a liquid molecule are designated by the references
- F1, F2 and F3 with two right angle bends in a first mixing chamber,
- F4 in a circular arc in a transfer chamber with two elbows at right angles at both ends to pass from the direct longitudinal direction LD in the two compartments of the first mixing chamber to the reverse longitudinal direction LI in the inlet compartment from the second mixing chamber,
- F5, F6, F7, in this second mixing chamber with two bends at right angles and with return to the direct longitudinal direction in the brewing compartment.

A symmetrical thread section of the thread F4 is shown at F8 in the other transfer chamber. These two threads meet at their two ends.

The tube TA, TB, TV, TF, TE is in alignment between two sections 22 and 24 of an outer pipe of the same diameter.

The envelope 8 protrudes from this pipe. The connection of this tube between two sections of this pipe is done easily and does not create any loss of connection load, that is to say other than those which occur inside the device to effect the desired homogenization.

The second device according to the invention comprises an axial core 100 and a cylindrical envelope 102 along said axis A. Said mixing and transfer chambers succeed one another circumferentially and longitudinally in the annular interval between this core and this envelope. Each of said mixing chambers comprises a said planar perforated wall 104, 110 having a radial and longitudinal extent, said first and second transverse directions being the radial DR and circumferential directions DC, respectively.

In Figure 4 the radial direction DR is at all points perpendicular to the sheet.
Two so-called feed and brewing compartments for this chamber are formed by this perforated wall and by two helical guide walls 106, 108, for one chamber and 108, 112 for the other chamber. One of these two walls is a separating wall 108 common to the two chambers. The mixing chamber 106, 108 constitutes a said inversion chamber, the two said helical guide walls 106, 108 of this chamber having opposite inclinations. The two said helical guide walls 108, 112 of the other said mixing chamber have inclinations in the same direction.
Each of said supply and stirring compartments extends, as does said guide wall 106, 108, 112 forming this compartment, over an angular sector of 120 degrees S1, S2, or S3. Two compartments belonging one 104, 108 to one of said mixing chambers, the other 110, 108 to the other of these chambers are formed in the same angular sector S2 and are located longitudinally on either side of the separating wall 108.

Said transfer chamber comprises a transfer wall 114 which extends radially and circumferentially by occupying two S2, S3 of said angular sectors of 120 degrees. It also has two connecting walls 116 and 118 which extend radially and longitudinally.

The path of a liquid molecule is shown in F10.

The casing 102 is connected coaxially to a pipe of the same diameter, not shown. Upstream of the wall 114 and downstream of the walls 106 and 112 of the inlet 120 and outlet 122 connection walls gradually vary the cross section of the fluid in the pipe to limit the pressure drop.

The third device according to the invention comprises:
- A cylindrical envelope 200 around said axis A.
- Three separating walls PPQ, PQR, PRP longitudinally coextensive and each extending radially from said axis to said envelope by forming three said mixing chambers. Each of these chambers occupies an angular sector SP, SQ, SR extending over 120 degrees around said axis, and has two ends longitudinally which constitute its said inlet PE and outlet PS.
- Three so-called perforated walls PP, PQ, PR in these three chambers, respectively. Each of these walls extends in an oblique direction relative to said longitudinal directions LD and radial DR, and also extends in said circumferential direction DC so as to separate said supply compartments PPQ, PRF, PP, PE and PPQ, PEP, PP, PS mixing. As a result, said first and second transverse directions are said circumferential and radial directions, respectively, that the speed of said jets has not only said component in this second transverse direction, but also a longitudinal component, that none of these mixing chambers constitutes a said inversion chamber, and that said offset direction is circumferential.
- And two said transfer chambers at the two ends, respectively, of all of these three mixing chambers, in said envelope 200. These two transfer chambers are angularly offset by 120 degrees. Each of them has
a transfer wall TPQ occupying two said angular sectors SP, SQ, at a distance beyond the extreme edge of said separating wall PPQ which separates these two sectors,
- And two connecting walls MRP, MQR extending the other two so-called separating walls PQR, PRP to this transfer wall, so as to connect in series the three said mixing chambers.

More particularly, said perforated walls are fractions of cones of revolution around said axis A. The half-angles at the top of these cones are called here the angles of obliquity of these walls. The oblique angle of that PQ of these walls which is in said angular sector SQ common to the two said transfer walls TPQ, TQR is opposite to that of the other two said perforated walls PP, PR, so that the radial component of the speed of said jets is in the same direction through the three said perforated walls.

In the example given, this radial component is directed towards the axis and said obliquity angle is equal to thirty degrees.

The successive sections of the path of a fluid molecule are represented
- in F21, F22, F23 in a first mixing chamber on either side of the perforated plate PP,
- in F24 with two right angle bends in a downstream transfer chamber limited by the TPP wall,
- in F25, F26 and F27 in a second mixing chamber on either side of the perforated wall PQ, in F28 with two bends at right angles in an upstream transfer chamber limited by the wall TPQ,
- And in F29, F30 and F31 in a third mixing chamber comprising the perforated wall PR.

The inlet and outlet sections are sections F21 and F31, respectively. Said jets through the perforated plates are the sections F22, F26 and F30.

The device is connected coaxially to a pipe 202, not shown, of the same diameter as the casing 200.

Upstream of the TQR wall and downstream of the TPQ wall, the inlet and outlet connection walls, not shown, gradually vary the cross-section of the fluid passage to minimize the connection pressure drop.

à

en valeurs relative, et pour des valeurs de viscosités cinématiques de ces fluides de l'ordre du centistokes, la qualité de mélange obtenu est remarquable, depuis des vitesses centimétriques jusqu'à des vitesses dépassant le mètre par seconde dans la conduite.
Le tube TA, TB, TC, TD, TE, du premier dispositif peut avoir un diamètre de 100 mm et une longueur de 240 mm. Toujours dans les mêmes cas l'enveloppe 102 du deuxième dispositif et l'enveloppe 200 du troisième peuvent avoir une longueur de 450 mm et un diamètre de 100 mm, incluant les zones de raccordement.For cases where the concentration of the minority fluid to be mixed goes from 1% (with the addition of this fluid in the center of the upstream section) to 50%, the differences in density of the fluids to be mixed are

at

in relative values, and for values of kinematic viscosities of these fluids of the order of a centistokes, the quality of mixture obtained is remarkable, from centimetric speeds to speeds exceeding one meter per second in the pipe.
The tube TA, TB, TC, TD, TE, of the first device can have a diameter of 100 mm and a length of 240 mm. Still in the same cases, the casing 102 of the second device and the casing 200 of the third can have a length of 450 mm and a diameter of 100 mm, including the connection zones.

The perforated walls TA and TB of the first device may each comprise 50 to 60 circular holes 20 with a diameter of 10 mm.

The perforated walls 104 and 110 of the second device may each comprise 50 to 60 holes with a diameter of 10 mm.

The perforated walls PP, PQ and PR of the third device can each comprise 50 to 60 holes with a diameter of 10 mm.

The dimensions shown correspond for the second and third devices to an outside diameter of the device which is the same as that of the pipe.

Claims (8)

1 / Static device for homogenizing a circulating fluid, comprising:
- an inlet (2) having an axis and a diameter for receiving an inlet flow of said fluid along said axis from an upstream side of this device;
- An outlet having the same axis and the same diameter to restore an outlet flow of said fluid along said axis on a downstream side of this device, this axis being a device axis and having a longitudinal direction perpendicular to transverse directions which are in particular radial and circumferential directions, this diameter being that of a reference surface which is cylindrical and coaxial with this device,
- and mixing chambers connected between this inlet and this outlet and each comprising a supply compartment (TC, TA, TD, 6), and a brewing compartment separated by a perforated wall (TA, PAC, 8, PAD) to receive threads (F1) of said flow in this supply compartment and to form a plurality of jets (F2) which are perpendicular to this wall and which enter this mixing compartment to stir said fluid therein, this wall having a longitudinal extent and an extent in a first said transverse direction (DC) in order to present a large area in a radially limited space, so that these jets have speed components in a second said transverse direction (DR) perpendicular to the first, these supply and stirring compartments being further delimited by inlet (TC, 6, TD) and outlet (PAC, 8, PAD) guide walls which leave an inlet (2) of this chamber open. ns this supply compartment and an outlet from this chamber in this mixing compartment, these guide walls having an extension opposite said perforated wall so as to give said flow a direction (LD) substantially parallel to this perforated wall in each of these compartments with curvature of said threads on either side of this perforated wall,
- said perforated walls (TA, TB) being at least partially contained in said reference surface and longitudinally coextensive so as to limit the longitudinal and radial size of the device,
said mixing chambers being offset transversely with respect to one another in a transverse offset direction (DC),
- this device being characterized by the fact that it includes transfer means (TE, 14, 8, 16) for connecting the outlet of a first said mixing chamber (6, TC, PA6, 8, PAD, TD) at the inlet of a second so-called mixing chamber (6, TD, PBD, 8, PBC, TC) so as to connect these two chambers in series by making them pass successively through the same thread of said stream (F1, F2, F3, F4, F5, F6, F7). 2 / Device according to claim 1, characterized in that said inlet guide walls (TC, 6, TD) and outlet (PAC, 8, PAD) give said flow a substantially longitudinal direction in each of said compartments. supply (TC, TA, TD, 6) and mixing (TA, PAC, 8, PAD) of each said mixing chamber, these walls comprising a main guide wall (6, 8) facing said perforated wall (TA , TB) and inclined with respect to this perforated wall so as to deviate therefrom towards said inlet and said outlet of said mixing chamber, respectively,
said transfer means comprising at least one transfer chamber (TE, 14, 8, 16) which has an extent in said offset direction (DC),
- Said device comprising a succession of inversion chambers in an even number on the path of each thread of said flow, each of these chambers reversing the longitudinal component of the average speed of the fraction of said flow which traverses it, at least one of these chambers inversion being constituted by said transfer chamber. 3 / Device according to claim 2, wherein each of said transfer chambers (TE, 14, 8, 16) extends from a single said upstream or downstream side of all of said mixing chambers, directly connects two of these chambers and constitutes a single said inversion chamber, so as to allow a simple embodiment of the device. 4 / Device according to claim 3, characterized in that the number of said mixing chambers is two, these chambers being a first (6, TC, PAC, 8 PAD, TD) and a second (6, TD, PBD, 8 , PBC, TC) chambers comprising a first (TA) and a second (TB) said perforated walls separating a first and a second said supply compartments from a first and a second said brewing compartments, the inlet ( 2) of this first chamber and the outlet (4) of this second chamber constituting the inlet and the outlet of said device, respectively, one of these two chambers being an inversion chamber, the number of said transfer chambers (TE , 14, 8, 16) being one on the path of each thread (F1, F2, F3, F4, F5, F6, F7) of said stream. 5 / Device according to claim 4, characterized in that the two said perforated walls (TA, TB) are formed in two angular sectors of a tube (TA, TB, TC, TD, TE) which materializes said reference surface ,
a generally oblique separating wall (6) closing off this tube while separating these two perforated walls to form in this tube said supply compartment (2, TC, TA, TD, 6) of a first said mixing chamber, and said mixing compartment (4, TC, TB, TD, 6) of a second said mixing chamber,
said mixing compartment (TA, PAC, PAD, 8) of this first mixing chamber, said supply compartment (TD, PBC, PBD, 8) of this second mixing chamber, and said transfer means (TE, 8, 14, 16) being formed radially outside of this tube in an envelope (8),
- two lateral guide walls (PAC, PAD and PBC, PBD) having longitudinal and radial expanses being located angularly on either side of each of the two said perforated plates, to constitute with said envelope (8) said mixing compartment (TA, PAC, PAD, 8) of said first mixing chamber and said supply compartment (TB, PBC, PBD, 8) of said second mixing chamber,
- Said tube extending into an additional section (TE) which is located on a said upstream or downstream side of the assembly of the two said mixing chambers, inside said envelope, and which extends angularly in the two angular sectors of the two said perforated walls (TA, TB) and in at least one angular transfer sector (TC, TD) joining the two previous,
- a transverse external transfer wall (14) joining said additional section to said casing (8) and at least one transverse internal transfer wall (16) joining said section (TE) to said casing (8) in said angular transfer sector , so that said additional section, said envelope opposite this section and the two said transverse transfer walls constitute said transfer chamber (TE, 8, 14, 16). 6 / Device according to claim 4, characterized in that it comprises an axial core (100) and a cylindrical envelope (102) substantially materializing said reference surface, said mixing and transfer chambers succeeding each other circumferentially and longitudinally in the 'annular interval between this nucleus and this envelope,
each of said mixing chambers comprising a said flat perforated wall (104, 110) having a radial and longitudinal extent and separating two said supply and mixing compartments further delimited by two helical guide walls (106, 108), ( 108, 112), respectively, one of which (108) is common to the other known as the mixing chamber,
- one of these mixing chambers being a said inversion chamber, the two said helical guide walls (106, 108) of this chamber having opposite inclinations, the two said helical guide walls (108, 112) of the other said mixing chamber having inclinations of the same direction,
- A said transfer chamber comprising a transfer wall (114) which extends radially and circumferentially to connect these two mixing chambers. 7 / Device according to claim 3, characterized in that it comprises
- a cylindrical envelope (200) substantially materializing said reference surface,
- three separating walls (PPQ, PQR, PRP) longitudinally coextensive and each extending radially from said axis to said envelope by forming three said mixing chambers which each occupy an angular sector (SP, SQ, SR) around said axis, each of these chambers having two ends longitudinally which constitute its said inlet (PE) and outlet (PS),
- three said perforated walls (PP, PQ, PR) in these three chambers, respectively, each of these walls extending in an oblique direction relative to said longitudinal (LD) and radial (DR) directions, and extending according to said circumferential direction (DC) so as to separate said supply (PPQ, PRP, PP, PE) and mixing (PPQ, PEP, PP, PS) compartments, so that said first and second transverse directions are said circumferential directions (DC) and radial (DR), respectively, that the speed of said jets has not only said component in this second transverse direction, but also a longitudinal component, that none of these mixing chambers constitutes a said inversion chamber, and that said offset direction is circumferential,
- And two said transfer chambers at the two ends, respectively, of all of these three mixing chambers, in said envelope (200), each of these two chambers comprising
a transfer wall (TPQ) occupying two said angular sectors (SP, SQ), at a distance beyond the extreme edge of said separating wall (PPQ) which separates these two sectors,
- And two connecting walls (MRP, MQR) extending the other two said separating walls (PQR, PRP) up to this transfer wall, so as to connect the three said mixing chambers in series. 8 / Device according to claim 7, characterized in that said perforated walls are fractions of cones of revolution around said axis (A), the half angles at the top of these cones being angles of obliquity of these walls, l the obliquity angle of that (PQ) of these walls which is in said angular sector (SQ) common to the two said transfer walls (TPQ, TQR) being opposite to that of the other two said perforated walls (PP, PR), so that the radial component of the speed of said jets is in the same direction through the three said perforated walls.

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