DK142450B - Aggregate for generating fluctuations in liquids. - Google Patents

Description

(11) PRESENTATION 142450 en] \ R & y DENMARK (51), nt'CI'3 I S? F ιί / 702 (21) Application No. 4565/72 (22) Filed on the 4th S ep. 1972 (24) Race day Sep 4 1972 (44) The application presented and the publication document published on 5 · HOV. 1 98Ο

Dl THE RECTORATE OF _. ^ .., THE PATENT AND TRADEMARK BASIS <3 °) Pnor, tted from the

Sep 5 1971, 71519754 FR

20 dec. 1971, 7145758, FR

Jun 27 1972, 7225201, FR

(7i) COMPAGNIE FRANCAISE DE RAFFINAGE, 5, Ms Michel-Ange, 75016 Paris, FR.

(72) Inventor: Louis Duthion, 26 rue Boileau, 75016 Paris # FR: Claude Chars ·· les Doyotte, 64, Avenue Raymond Crosland, 92550 Le Piessis Robinson, FR:

Claude Jean Marie Seguela, 8 Aliee Henri WaJLlon, 95100 Argenteuil, FR:

Gabriel Barthelemy, 25 rue de Turbigo, 75002 Paris, FR: Alaln £ in = quanta, Hue Edouard Larue, 76 Le Havre, FR: Yves Drapeau, 14 rue P ± c = pus, 76 Le Havre, FR.

(74) Plenipotentiary in the proceedings:

Dansk Patent Kontor ApS._ (54) Aggregate for generating fluctuations in liquids.

The present invention relates to an assembly for generating fluctuations in liquids, in particular for the preparation of emulsions, and comprising a membrane disposed between at least one pair of mutually recessive and interconnected recesses, one of which has an outlet.

It is known that an air or liquid jet from a narrow nozzle opening, in front of which is placed a thin, narrow slat, one end of which is fixed, turns this slat into oscillations as the vibrations of the slab propagate to the flowing medium. The frequency of oscillation depends on the geometric shape of the slat, on its placement or, more generally, on its orientation, and on the conditions of the outflow of the liquid medium.

2

1424SO

Call such a procedure, km can be carried out continuously by. using an assembly with a very resistant lamella that can easily vibrate for a long time. This condition necessitates the use of metals that are particularly resistant to metal fatigue caused by periodic deformations.

US Patent No. 3,169,013 discloses a liquid emulsifier and homogenizer having an oscillating plate 20 which splits one at high velocity from a jet of jet emitting liquid. This cleavage results in a homogenization of the liquid phase. However, when using two plates as stated in the US patent, namely a nozzle plate and a vibration plate, one must not only make sure that the parts are aligned and check that the parts are similar, but they must also be replaced frequently. two parts.

The object of the present invention is to provide an assembly for producing ultrasound in liquids which is not conditioned by the use of a material having particular properties for producing the vibrating element. This is achieved by a special application of the vibrating element.

This object is achieved by an assembly of the type indicated in the introduction and characterized in that the paired recesses are formed in flanges on both sides of the membrane and that the membrane has a first, a liquid inlet forming membrane cut-out which goes into a second diaphragm cut through which the recesses facing each other are interconnected.

In this particular design of the membrane cuts and placement of the same, in practice a highly satisfactory homogenization of emulsions is achieved.

By using an aggregate according to the invention for the preparation of emulsions of water in boiler oil for boilers, the various variable factors such as e.g. the number of recesses, their dimensions and volume, and the dimensions of the cutouts in the membrane, values appropriate to the installation performance. These variable factors thus have specific values for each given installation. According to the invention, however, it has been envisaged to produce these assemblies such that the same flanges are suitable for a wide variety of given installations, only the diaphragm being characteristic of each installation given on this page, and thus separate determination can be made of the suitable factors for the flanges and, on the other hand, the suitable factors for the membrane.

Thus, according to the invention, standard parts can be used for use in all installations whose thermal output is between 30 and 700 megacal / h. The benefits of this are obvious to one of ordinary skill in the art and do not require any further explanation.

In the more general embodiment of the assembly according to the invention, standardized flanges are provided with a maximum number of recesses so that these flanges are applicable within a wide range of applications.

The adaptation to a particular performance is achieved by selecting a diaphragm placed between two standardized flanges and thus it is possible to vary only three factors: 1) the number of recesses utilized; 2} the thickness of the membrane; 3) the size and shape of the cutouts in the membrane.

The number of recess pairs used depends solely on the number of cutouts in the membrane. The more cuts the membrane has, the more recess pairs are connected and the greater the performance of the unit (all other conditions are otherwise equal). The thickness of the membrane, e.g. may vary between 10/100 and 20/100 mm with, if necessary, 1/100 mm range, determines the width of the fluid jet pressed into the assembly through one or more primary cuts in the membrane. The greater the width, the greater the amount of fluid the unit provides (the number of cuts unchanged).

The performance increases with the size of the cuts if all other conditions are kept unchanged.

142450 4

If the assembly is used to prepare boiler oil emulsions for heating boilers, a wide range of performance, e.g. from 30 to 700 megacal / h, is covered by a flange pair provided with the number of recess pairs needed to supply a boiler at 700 megacal / h. The specific performance of the installation is achieved by the use of a membrane placed between the two flanges and the thickness and number of cuts being adapted to the intended performance.

However, the present invention relates in particular to the use of the aforementioned aggregates for the preparation of emulsions of paraffin or wax in water. By "paraffin" is meant a single paraffin or a mixture of paraffins with crystalline structure, the melting point of which is between 45 and 66 ° C, where a significant proportion (generally at least 40% by weight) consists of straight-chain saturated aliphatic earbon hydrides having an oil content of less than 5% and preferably below 1%. "Wax" means a mixture of saturated hydrocarbons having a molecular weight far above the molecular weight of paraffin, a wax consisting of larger amounts of saturated cyclic or branched hydrocarbons and usually contains more oil than a paraffin.The wax is microcrystalline and its melting point is between 66 and 90 ° C.

It is known that emulsions of paraffin or wax have numerous uses, being particularly used to waterproof wooden building boards or other materials or to impregnate paper.

In the present state of the art, these emulsions are usually prepared by dispersing liquid paraffin in water in the presence of a certain amount of emulsifier. Stirring is carried out in a known manner by means of a conventional stirrer equipped with wings or by a kind of turbine. If the emulsifier is ionic, it can be synthesized in situ; eg. For example, anionic emulsions of paraffin can be prepared by reacting an amine with a fatty acid, adding the amine and fatty acid together or separately to the water and / or paraffin.

The described use of aggregates according to the invention for preparing emulsions of paraffin or wax in water is characterized in that the water, paraffin or wax and the emulsifier are introduced into the emulsion assembly through a common opening and in that the emulsion c 142450 is collected and discharged through a second aperture associated with at least one pair of recesses in the flanges, the pressure difference between one and the other aperture being greater or equal to 2 bar.

Aggregates or parts of aggregates according to the invention and their preparation for extraction of water emulsions in heating oil and emulsions of paraffin or wax in water are explained in the drawing as follows: FIG. Fig. 1 is a front view of a membrane whose design corresponds to an aggregate of the former type; 2 is a section a-a of FIG. 3, showing an assembly according to the invention provided with a membrane as shown in FIG. 1, FIG. 3 is a section b-b of the assembly shown in FIG. 2, FIG. Figure 4 is a front view of a membrane whose design also corresponds to a first type assembly; 3 is a sectional view along the plane of symmetry perpendicular to the diaphragm showing an assembly provided with a diaphragm as shown in FIG.

4, FIG. Figure 6 is a front view of a membrane, the embodiment of which corresponds to an aggregate of the latter type; 7 is a sectional view along the plane of symmetry perpendicular to the diaphragm showing an assembly provided with a diaphragm as shown in FIG. 6, FIG. 8, 9, 10 and 11 relate to an assembly according to the invention for preparing an emulsion of water in heating oil, fig. Figure 8 is a front view of a flange provided with eight recesses;

9 is a front view of another flange also provided with eight recesses; FIG. 10 is a front view of a diaphragm provided with two cuts, and FIG. 11 is a sectional view of an assembly according to the invention; FIG. 12 and 13 show an assembly according to the invention, useful for preparing emulsions of paraffin or wax in water, fig. 12 to illustrate an emulsifier in perspective and unfolded fan-shaped; FIG. Figure 13 is a schematic diagram illustrating an emulsifying assembly with its supply and auxiliary means.

FIG. 1, 2 and 3 show a thin circular stainless steel membrane 1, which is provided at the top with a funnel-shaped cut 2 with a radius in the membrane as a axis of symmetry. The cut-out 2 is followed by a cut-out 3, so that both cut-outs 2 and 3 together form a funnel.

It is convenient to provide the bottom of the cut with an oblique cut edge 4 on one or both sides of the diaphragm.

The diaphragm is placed between two flanges 5 and 6, both provided with a recess 7 and the free space delimited by the cutout 2 constitutes a passage whose rectangular cross-section decreases towards the center of the diaphragm and through which the liquid is introduced into the assembly. . The cutout 3 forms a passage for the liquid from one recess to the other.

The liquid is removed through the outlet 9, whose axis should not be parallel to the inlet axis · In fig. 2 is thus e.g. shown an outlet 9 whose axis is perpendicular to the axis of the membrane.

To simplify the drawing, the means used to clamp the two flanges to each other are not shown. For clamping, any known agent can be used. Thus, the unit may be provided with e.g. clamping bolts passing through flanges 5 and 6 as well as diaphragm 1. It is also possible to screw the two flanges together.

The recesses 7 and & g preferably have their main axis parallel to the axis of the inlet of the liquid in the cutout 2. The recesses can have the same volume and be shaped like a parallel pipedum. The liquid is supplied to the unit through the cutout 2 and leaves it through the outlet 9 ·

It is presumed that the generation of ultrasound can be explained as follows:

The unit acts as a liquid oscillator due to the presence of the two recesses 7 and S filled through a common inlet. The pressure difference between the two recesses 7 and 8 causes the membrane to vibrate. The conditions for optimum effect are that the frequency of the liquid ice between the two recesses is the same as the intrinsic frequency of the membrane 1. The dimension of the recesses should be such that this resonance occurs.

FIG. 4 and 5 show a thin circular stainless steel diaphragm 10, which is provided at its upper part with two cuts, each with a radius in the diaphragm as the axis of symmetry. The cutout 12 is followed by a secondary cutout 13 consisting of two branches. These define a strip 14 which conveniently ends in an obliquely cut surface 14A on one or both sides.

The diaphragm 10 is clamped between the two flanges 15 and 16. The flanges are provided with recesses 17 and 18, one of which is provided with an outlet pipe 19.

FIG. 6 and 7 show a thin circular stainless steel membrane 20, in the center provided with a cut 21, followed by two additional cuts 22 and 23, each forming a slat 24 and 25. The liquid is introduced through a channel 26. The flanges 27 and 28 is provided with two recesses 29 and 30 at the top and 31 and 32 at the bottom. Each recess pair is provided with a discharge channel 33 and 34 respectively.

One use of aggregates according to the invention is for the preparation of emulsions, more specifically emulsions of water in heating oil. It is known that these emulsions can be combusted instead of the pure fuel as this use reduces the amount of carbon oxide and unburned hydrocarbons in the flue gas.

A mixture of water and fuel oil in appropriate proportions is fed into the internal recesses of the flanges through the cutout 2 (or 12 or i · 21). Mix water and fuel oil before loading into a regular mixing vessel; but it is also possible to allow water and fuel oil to flow through two branches of a T-pipe or to allow a water supply pipe to flow into a pipe through which the fuel oil flows. In this case, it would be useful to use a non-return valve to prevent the fuel oil from entering the water pipes in the event that the water pressure should accidentally drop. Advantageously, the funnel-shaped cut-outs 2 or 12 are provided with a readily accessible filter which only has to consist of a plain plate of burnt material, the filter preventing a rapid contamination of the internal parts of the unit with dust and impurities from the fuel oil and water.

8 142450

The notch 3 (or 13, or the notches 22 and 23) connect the recesses in each pair.

The emulsion is discharged through channels 9 (or 19, or 33 and 34). The performance of emulsion depends on the thickness of the slat and the dimensions of the cut 2 (or 12 or 21).

The frequency of the oscillations depends on the internal geometric dimensions of the aggregate, as this frequency may vary between 8000 and 40000.

The first type of unit is suitable for feeding small burners (20 to 40 megacal / h) as well as larger burners (up to 750 megacal / h), while the second type of unit is particularly suitable for feeding larger burners (350 to 900 megacal / h). h).

Example 1.

This example relates to an assembly similar to FIG. 1, 2 and 3. The membrane has the following data:

Diameter: 18 mm

Thickness: 0.12 mm

Material: chrome-nickel steel 18 / $ Length of cut (2 +: 3, 6 mm

Size of the cutout 2 at the periphery of the membrane: 3.4 mm Width of the cutout 3 measured over the inclined edge: 0.7 mm. The membrane is clamped between two brass flanges screwed together along the periphery. The goals of the recesses are as follows:

Depth: 1 mm

Area: 11 x 5 mm

By supplying an aggregate as described 5.7 l / h of a mixture of ordinary heating oil with 20% by volume of water, an emulsion is obtained which can supply a burner at 30 megacal / h, with the oscillation number being 15-000 Hz.

Example 2.

This example relates to an assembly similar to FIG. 4 and 5 · The membrane has the following data: 9 142450

Diameter: 20 mm

Thickness: 0.25 mm

Material: Steel Z 30 C 13 Length of cut (12): 4 mm Length of slat (14): 16 mm

Area of the slat (14): 3 mm x 6 mm

Area of cut (13): 1 mm x 6 mm

The diaphragm is jammed between two flanges. The dimensions of the recesses in the flanges are as follows:

Depth: 1 mm

Area: 11 mm x 6 mm

Adding such an aggregate 57 l / h of a mixture of ordinary heating oil and 20% by volume of water gives an emulsion capable of supplying a burner at 300 megacal / h. The oscillation number is 1250 Hz.

Example 3

This example relates to an assembly similar to FIG. 6 and 7. The membrane has the following data:

Diameter: 40 mm

Thickness: 0.20 mm

Material: chrome nickel steel 15/8

Area of cut (21): 10 mm x 3 mm

Area of the slats (24 and 25): 3 mm x 6 mm

The diaphragm is clamped between two flanges whose recesses have the following data:

Depth: 1 mm

Area: 11 mm x 6 mm

By adding this device 86 l / h of a mixture of light heating oil and 20% by volume of water, an emulsion is obtained which can supply the burner in a boiler at 500 megacal / h. The oscillation number is 3 * 600 Hz.

Referring to FIG. 8-11, an embodiment of the invention for use in the preparation of emulsions of water in fuel oil will be explained here.

ίο 142450

FIG. S shows the flange 51 provided with eight recesses 52.

Each recess is provided with a cylindrical channel 53 which connects the two sides of the flange. Two non-penetrating holes 54 and 55 are drilled into the flange 51 · The periphery of the flipped-off. side of the flange is torn (dotted line 56) as shown in FIG. 8th

FIG. 9 shows the flange 57, which is also provided with eight recesses 58 arranged in the same position as the recesses 52 in the flange 51 · In the flange 57, two pins 59 and 60 are arranged for centering, respectively, which fit into one and the other holes respectively. 54 and 55.

The flanges 51 and 57 constitute a pair of flanges which can be used within a large capacity range. The diaphragm placed between said pair of flanges determines the exact range of application of the assembly, on the one hand depending on the thickness of the diaphragm and on the other hand on the size and number of cuts provided with the latter. This number may in the present case be between 1 and 8.

FIG. 10 shows a diaphragm 61, the diameter of which corresponds to the diameter of the flanges 51 and 57, and which is provided with two cuts 62 and 63. These cuts are composed of a primary cut 64 of the membrane, starting from the periphery of the membrane, and a secondary cut 65, which is a continuation of the first cut, the edges of the secondary cut being parallel to one another. The primary and secondary carvings together form a funnel-shaped joint inlet. The bottom of the funnel-shaped cut perpendicular to the edges of the secondary cut may be obliquely cut. This is not shown in FIG. 10. The cutouts 62 and 63 have the same axis of symmetry as the recesses 51 and 57 in the flanges. It is not necessary that the two cuts be placed side by side.

The diaphragm 6l is provided with two holes 66 and 67 having the same dimensions as the two holes 54 and 55 and placed respectively in the same position.

In FIG. 11 is shown how the housing 68 is provided with a bore 69 in which the two flanges 51 and 57 are arranged, the membrane 6l being arranged between the two flanges. The bore 69 is followed by a piece of 70 with internal thread, into which is screwed the threaded portion 71 of the clamping piece 72. By tightening the two pieces 68 and 72, these flanges 51 and 57 are pressed firmly against each other.

73 suggests a gasket. The liquid or liquid mixture is pumped through the inlet 74, which opens into the bore 69 in the housing 68, the same bore communicating with the bore 75, which acts as a distribution channel. The liquid or emulsion is guided away from the recesses through the bores 53 and further from the assembly through the bore 76 which terminates with a piece of internal thread 77 ·

The pressure loss can be kept almost constant no matter how large the performance is, depending on the data of the membranes (thickness, number and size of the cuts).

When used to supply fuel by a burner to a steam or boiler, the pressure drop in the fluids found between the inlet and outlet of the unit is almost constant and independent of the boiler's capacity. This pressure loss can e.g. be between 2 and 4 bar.

The vibration frequency can e.g. be between 10,000 and 25,000 Hz.

A filter device for the unit is required if you want the unit to maintain its full operation for a long time.

The following example 4 relates to an assembly similar to FIG. 8, 9, 10 and 11.

Example 4

The flanges data are as follows:

Diameter: 40.0 mm

Width of the recesses: 5.0 mm

Total length of the recesses: 10.5 mm

Distance from the lower edge of a recess to the center of the flange: 7.0 mm

Distance from center of channels 53 to center of flange: 15 mm Diameter of channels 53: 3 mm 12 142450

Diameter of hole 54 and pin 59: 3 mm Diameter of hole 55 and pin 60: 3 mm

The membrane data is as follows:

Diameter: 40.0 mm

Depth of the two cuts 62 and 63: 2.5 and 1.0 mm respectively, i.e. a total of 3.5 mm Length of cut at the periphery of the membrane: 3> 4 mm

The supply of 80 l / h of a mixture of ordinary heating oil and 20% by volume of water gives an emulsion which can supply a burner 500 megacal / h. The vibration frequency is 15-000 Hz.

Referring to FIG. 12 and 13, a process according to the invention for preparing an emulsion of paraffin or wax in water is explained here.

The diaphragm 101 provided with a cut 102, the bottom 103 of which is inclinedly cut, is (when the assembly is in operation) disposed between two flanges 104 and 105, each provided with a recess 106 and 107. and emulsifier is passed into the emulsifier assembly through the cutout 102 and the stream of emulsion is collected through the tube 108 which communicates with the interior of the assembly. The recesses 106 and 107 communicate with each other through the portion of the cut 102 which is closest to the obliquely cut edge 103.

It is advantageous to premix the constituents of the emulsion, i.e. the paraffin, water, and emulsifier before being introduced into the emulsifier. This can be done in a known manner by passing the inlets of paraffin, water and emulsifier into a common tube before they are fed into the emulsifier.

The components of the emulsion are fed into the emulsifier under pressure. For this, an inert gas may be used which exerts pressure on the surface of the components, each placed in its feed container, or a pump placed on each feeding tube between the feed containers and the place where the various components run together.

13 142460

The pressure at the outlet of the unit can be regulated by means of a backpressure valve, without which the pressure at the outlet corresponds to the atmospheric pressure.

It has been found that the difference in pressure between the inlet and the outlet of the unit must be at least 2 bar. If the pressure difference is less than two bar, the emulsion becomes very thick and unstable, as will be seen in the experiments discussed later.

The components of the emulsion must be fed into the emulsifier at a temperature generally between 80 and 99 ° C. The exact value depends on the paraffin used. For a given paraffin, it is no higher than the temperature used in the known process for preparing an emulsion.

FIG. Figure 13 shows a schematic diagram of the assembly of an emulsifying assembly and associated auxiliary means. The emulsifier 111 is fed through a tube 112 with a mixture of paraffin, emulsifier and water. The paraffin and the emulsifier are passed to the emulsifier 111 through the tube 113 by the pressure exerted by the nitrogen located over the free surface of the liquid in the container 114 · The water is passed through the tube 115 to the emulsifier 111 by the pressure of the The reference numerals 117 and 118 indicate the filters, and the pipes 113 and 115 are each provided with a control valve 119 and 120 and a check valve 121 and 122. The nitrogen is supplied through the tube 123 to the container 114 and 116, maintaining the pressure at the desired value. The containers 114,116 are provided by the pipes, respectively. 124 and 125. The emulsion is discharged from the emulsifier assembly 111 through the tube 126 provided with a backpressure valve 127 if desired.

The filling of the containers 114 and 116 may be continuous or discontinuous through the tubes 124 and 125. The reference numeral 128 indicates a paraffin supply means and the reference numerals 129 and 130 indicate control valves.

All of the above-mentioned means are in a room 131 in which the temperature is maintained at approx. 95 ° C. Outside this compartment is the container 132 for collecting the emulsion.

14 142450

According to the diagram described above, the emulsifier is added to the paraffin prior to the preparation of the emulsion. This can be accomplished by means of e.g. nonionic emulsifiers of the type of polymerized fatty acid alcohols or alkyl phenols with oxyethylene or oxypropylene or esters of fatty acids and polyalcohols or optionally amide derivatives of fatty acids and alkanolamines. Emulsifiers of these types can be added not only to the paraffin but also to the water prior to the preparation of the emulsion.

If the emulsifiers are synthesized in situ, e.g. may be the case with anionic emulsifiers of the type of aminated soaps, the constituents of the emulsifiers may be added together to the water or paraffin or to the water for one and the paraffin for the other.

The invention is further explained by the following example.

Example 5

By means of an emulsifier identical to that shown in FIG. 12 and with the following data:

Diameter of the membrane: IS mm

Thickness of the membrane: 11/100 mm

Width of cut: 70/100 mm

Depth of cut: 3.5 mm the unit was mounted as shown in fig. 13, and the following experiments were carried out, varying partly the composition of the emulsion and partly the tricyclic or ΔΡ. The temperature of the water and paraffin was 95 ° C.

The results are summarized in the following table: 15 142A50

Experiment # 1 2 3 4 T (6)

Composition of the emulsifier by weight;

Emulsifier (1) 6.0 6.0 6.0 6.0 6.0 6.0

Paraffin (2) 60.0 59.0 59.0 59.0 59.0

Water 34.0 35.0 35.0 35.0 35.0 ΔΡ (in bar) 0 (3) 269

Data for the emulsion:

Viscosity at 20 ° C

(in ° Angels) pressure 20 6.9 12 21

Shaking durability stable stable stable stable stable (4)

Centrifugation (5) 0 0 0 <1

Diameter of the particles (in u) 2 å 5 l å 21 a 3 1 a 2 irregular ΔΡ: Pressure difference between the input and output of the emulsifier.

(1) Composition of the emulsifier:

Mixture of sorbitan monostearate and polyoxyethylene stearic acid ester.

(2) Physical data for the paraffin:

Melting point: 52 ° C

Viscosity at 100 ° C: 3.2 centistoke Oil content: 2% by weight.

(3) Experiment # 1 was performed without vibrating membrane.

(4) Measured at 130 - 10 beats / min. with rashes of δ - 1 cm for 60 minutes. Stable indicates that the emulsion neither separates nor thickens.

(5) Measured in volume percent of separated water for 30 minutes subjected to an acceleration of 240 times the acceleration of gravity. 1

The emulsion "Tfr is prepared according to the known process, i.e. by stirring a mixture of paraffin, water and emulsifier

Claims (5)

16 1424S0 by means of an agitator rotating at a speed of 200 rpm. The tests, the results of which are presented in the above table, show that good quality emulsions are obtained if the pressure difference is equal to or higher than 2 bar. They have lower viscosity than the emulsion T prepared in a manner already known in the art. An assembly for generating oscillations in liquids, especially for the preparation of emulsions, and comprising a membrane disposed between at least one pair of opposite and interconnected recesses, one of which has an outlet, characterized in that: the pairwise recesses (7 and 8; 17 and 18; 29 and 50; 51 and 52; 52 and 58; 106 and 10) are formed in flanges (5 and 6; 15 and 16; 27 and 28; 51 and 57; 104 and 105) on both sides of the diaphragm (1; 10; 20; 61; 101) and the diaphragm (1; 10; 20; 61; 101) having a first, a fluid inlet forming diaphragm cutout (2; 12; 21; 64), which enters a second diaphragm cut (5; 13; 22; 25; 65) through which the opposite recesses (7 and 8; 17 and 18; 29 and 50; 51 and 52; 52 and 58; 106 and 107) are interrelated. Assembly according to claim 1, characterized in that the liquid inlet forming membrane cutout (2; 64) is formed in the periphery of the membrane (1; 61; 101) and constitutes the continuation of the second membrane cutout (5; 65) to form a single carving (62; 65; 102). An assembly according to claim 1, characterized in that the fluid inlet forming membrane cutout (12) is formed in the periphery of the membrane (10) and the second membrane cutout (15) has two arms limiting a slat (14) in the membrane ( 10). Assembly according to claim 1, characterized in that the liquid inlet forming membrane cut-out (21) is formed approximately in the middle of the membrane (20) and that the second membrane cut-out (22; 25) has a pair of associated recesses (29 and 50; 51). and 52) is based on this cut.