EP3769024B1 - Heat exchanger with imptoved liquid/gas mixing apparatus - Google Patents

Description

The present invention relates to a heat exchanger comprising series of passages for each of the fluids to be placed in a heat exchange relationship, the exchanger comprising at least one mixing device for distributing at least one two-phase liquid/gas mixture into one of the series of passes.

In particular, the present invention can be applied to a heat exchanger which vaporizes at least one flow of liquid-gas mixture, in particular a flow of mixture with several constituents, for example a mixture of hydrocarbons, by heat exchange with at least one other fluid, for example natural gas.

The technology commonly used for an exchanger is that of aluminum exchangers with brazed plates and fins, which make it possible to obtain very compact devices offering a large exchange surface.

These exchangers comprise plates between which heat exchange waves are inserted, formed of a succession of fins or wave legs, thus constituting a stack of vaporization passages and condensation passages, some intended to vaporize liquid refrigerant and the others to condense a calorigenic gas. Heat exchanges between fluids can take place with or without phase change.

In order to ensure the correct operation of an exchanger implementing a liquid-gas mixture, the proportion of liquid phase and of gaseous phase must be the same in all the passages and must be uniform within the same passage.

The sizing of the exchanger is calculated assuming a uniform distribution of the phases, and therefore a single temperature at the end of vaporization of the liquid phase, equal to the dew point temperature of the mixture.

For a mixture with several constituents, the end of vaporization temperature will depend on the proportion of liquid phase and gas phase in the passages.

In the case of an unequal distribution of the two phases, the temperature profile of the first fluid will therefore vary according to the passages, or even vary within the same passage. Because of this non-uniform distribution, it can then happen that the fluid or fluids in exchange relationship with the two-phase mixture have a temperature at the outlet of the exchanger higher than that expected, which consequently degrades the performance of the the heat exchanger.

One solution for distributing the liquid and gaseous phases of the mixture as evenly as possible consists of introducing them separately into the exchanger, then mixing them together only inside the exchanger.

The document FR-A-2563620 describes such an exchanger in which a grooved bar is inserted in the series of passages intended to channel the two-phase mixture. This mixing device comprises separate channels for a liquid phase and a gas phase and an outlet for distributing the liquid-gas mixture to the heat exchange zone. A heat exchanger according to the preamble of claim 1 is known to US 2016/290733 A1 .

A problem which arises with this type of mixing device relates to the distribution of the liquid-gas mixture in the width of the passage incorporating the mixing device. In order to proceed with the mixing of the two phases, the mixing device generally comprises a first channel for the flow of a phase. This channel is provided with a series of orifices arranged along the channel, each orifice being in fluid communication with the second channel for the flow of the other phase. When the inlet of the first channel is supplied with fluid, the flow velocity of the fluid will tend to decrease as the fluid flows along the channel. This is because the fluid flow decreases when the ports are energized.

However, the orifices are generally machined perpendicular to the direction of flow of the fluid and are therefore less well supplied when the speed of the fluid is greater. The orifices arranged on the channel inlet side therefore tend to be underfed, while the orifices located at the bottom of the channel are overfed. This results in an uneven introduction of the phase considered in the channel for the other phase, and hence an uneven distribution of the liquid-gas mixture in the width of the passage of the exchanger.

In order to minimize this phenomenon, one solution would be to supply the channel considered by two opposite inputs of the channel. However, the result is a complexification of the exchanger and the problem of inhomogeneous distribution remains at least in the central part of the channel.

Increasing the number of channels is also not an ideal solution from the point of view of the mechanical strength and the brazing of the device.

Another known solution consists in arranging orifices of cylindrical shape having different diameters along the channel. However, this solution may prove to be insufficient for certain processes.

The object of the present invention is to solve all or part of the problems mentioned above, in particular by proposing a heat exchanger in which the distribution of the liquid and gaseous phases of a mixture is as uniform as possible, and this without complicating excessively the structure of the exchanger, nor increase its size.

• au moins un premier canal pour l'écoulement d'une première phase du fluide parallèlement à la direction longitudinale,
• au moins un deuxième canal pour l'écoulement d'une deuxième phase du fluide, et
• plusieurs orifices reliant fluidiquement le premier canal au deuxième canal, lesdits orifices occupant des positions successives suivant la direction longitudinale,

caractérisé en ce que les distances entre les positions successives, mesurés parallèlement à la direction longitudinale, sont variables.The solution according to the invention is then a heat exchanger comprising several plates arranged parallel to each other and in a longitudinal direction so as to define several passages for channeling at least one fluid to be placed in heat exchange relationship with at least one other fluid. , a mixing device being arranged in at least one passage and comprising:

• at least a first channel for the flow of a first phase of the fluid parallel to the longitudinal direction,
• at least one second channel for the flow of a second phase of the fluid, and
• several orifices fluidically connecting the first channel to the second channel, said orifices occupying successive positions in the longitudinal direction,

characterized in that the distances between successive positions, measured parallel to the longitudinal direction, are variable.

• les distances entre les positions successives varient de façon monotone ou quasi-monotone suivant la direction longitudinale.
• le dispositif mélangeur présente, suivant la direction longitudinale, une augmentation des distances entre deux positions successives.
• le dispositif mélangeur présente, suivant la direction longitudinale, une diminution des distances entre deux positions successives.
• le dispositif mélangeur est divisé, suivant la direction longitudinale, en au moins une première portion et une deuxième portion, la première portion présentant, suivant la direction longitudinale, une augmentation des distances entre deux positions successives et la deuxième portion présentant, suivant la direction longitudinale, une diminution des distances entre deux positions successives.
• le dispositif mélangeur est configuré pour une introduction séparée de la première phase et de la deuxième phase dans le au moins un premier canal et dans le au moins un deuxième canal respectivement, le premier canal comprenant une première entrée adaptée pour alimenter ledit premier canal en la première phase du premier fluide et une deuxième entrée, séparée de la première entrée, adaptée pour alimenter ledit au moins un deuxième canal en la deuxième phase du premier fluide.
• le premier canal et/ou le deuxième canal sont de forme rectiligne.
• le dispositif mélangeur comprend une première entrée et une première entrée supplémentaire adaptées pour alimenter ledit au moins un premier canal en la première phase du fluide, la première portion étant située du côté de la première entrée et la deuxième portion étant située du côté de la première entrée supplémentaire.
• le dispositif mélangeur comprend plusieurs premiers canaux et plusieurs deuxième canaux, chaque premier canal comprenant au moins un orifice reliant fluidiquement ledit premier canal à un deuxième canal donné.
• le dispositif mélangeur comprend plusieurs premiers canaux se succédant suivant une direction latérale orthogonale à la direction longitudinale.
• le deuxième canal s'étend suivant une direction latérale orthogonale à la direction longitudinale.

Depending on the case, the exchanger of the invention may comprise one or more of the following technical characteristics:

• the distances between the successive positions vary monotonically or almost monotonically along the longitudinal direction.
• the mixing device has, in the longitudinal direction, an increase in the distances between two successive positions.
• the mixing device has, in the longitudinal direction, a reduction in the distances between two successive positions.
• the mixing device is divided, in the longitudinal direction, into at least a first portion and a second portion, the first portion presenting, in the longitudinal direction, an increase in the distances between two successive positions and the second portion presenting, in the longitudinal direction , a decrease in the distances between two successive positions.
• the mixer device is configured for a separate introduction of the first phase and the second phase into the at least one first channel and into the at least one second channel respectively, the first channel comprising a first input adapted to feed said first channel into the first phase of the first fluid and a second inlet, separate from the first inlet, suitable for supplying said at least one second channel with the second phase of the first fluid.
• the first channel and/or the second channel are rectilinear in shape.
• the mixing device comprises a first inlet and a first additional inlet suitable for supplying said at least one first channel with the first phase of the fluid, the first portion being located on the side of the first inlet and the second portion being located on the side of the first additional entry.
• the mixer device comprises several first channels and several second channels, each first channel comprising at least one orifice fluidically connecting said first channel to a given second channel.
• the mixing device comprises several first channels succeeding one another in a lateral direction orthogonal to the longitudinal direction.
• the second channel extends in a lateral direction orthogonal to the longitudinal direction.

1. i) agencer un dispositif mélangeur dans au moins un passage de l'échangeur,
2. ii) alimenter ledit premier canal du dispositif mélangeur en la première phase du premier fluide,
3. iii) alimenter ledit deuxième canal du dispositif mélangeur en la deuxième phase (62) du premier fluide (F1) distincte de la première phase (61),
4. iv) mettre en communication fluidique le premier canal avec le deuxième canal via les orifices de sorte qu'un mélange entre la première phase et la deuxième phase s'opère au sein du dispositif mélangeur, et

distribuer un mélange de la première phase et de la deuxième phase en sortie du dispositif mélangeur.Furthermore, the invention relates to a method for distributing a two-phase liquid/gas mixture in an exchanger according to the invention, said method comprising the following steps:

1. i) arranging a mixing device in at least one passage of the exchanger,
2. ii) supplying said first channel of the mixing device with the first phase of the first fluid,
3. iii) supplying said second channel of the mixing device with the second phase (62) of the first fluid (F1) distinct from the first phase (61),
4. iv) placing the first channel in fluid communication with the second channel via the orifices so that mixing between the first phase and the second phase takes place within the mixing device, and

distributing a mixture of the first phase and of the second phase at the outlet of the mixing device.

1. a) positionnement des orifices de manière à ce que leurs positions successives soit séparées par des distances prédéterminées,
2. b) alimentation du premier canal en la première phase du fluide de sorte que la première phase du fluide s'écoule suivant la direction longitudinale,
3. c) détermination des débits massiques de la première phase s'écoulant à travers chaque orifice,
4. d) pour chaque orifice, repositionnement de l'orifice suivant de sorte qu'il soit séparé de l'orifice d'une distance modifiée égale à la moyenne des distances prédéterminées multipliée par un facteur de correction, ledit facteur de correction étant déterminé en fonction du débit massique s'écoulant dans l'orifice.
   • le facteur de correction est une fonction du rapport entre le débit massique s'écoulant à travers l'orifice et le débit massique moyenné sur tous les orifices.
   • ladite fonction est une fonction polynomiale du rapport entre le débit massique s'écoulant à travers l'orifice et le débit massique moyenné sur tous les orifices, de préférence une fonction affine dudit rapport.
   • le procédé comprend en outre une étape e) de définition des distances modifiées à l'étape d) en tant que distances prédéterminées, les étapes c) à d) étant réitérées au moins une fois, de préférence entre 1 et 5 fois, de préférence encore 2 fois au plus.
   • le dispositif mélangeur comprend plusieurs premiers canaux, le procédé comprenant, préalablement à l'étape a), au moins une étape de sélection d'un sous-ensemble d'orifices agencés dans un même premier canal, les étapes a) à e) étant appliquées audit sous-ensemble.

According to another aspect, the invention relates to a method for adjusting the position of the orifices of a mixing device arranged in an exchanger according to the invention, said method comprising the following steps:

1. a) positioning of the orifices so that their successive positions are separated by predetermined distances,
2. b) supplying the first channel with the first phase of the fluid so that the first phase of the fluid flows in the longitudinal direction,
3. c) determination of the mass flow rates of the first phase flowing through each orifice,
4. d) for each hole, repositioning the next hole so that it is separated from the hole by a modified distance equal to the average of the predetermined distances multiplied by a correction factor, said correction factor being determined as a function of the mass flow flowing into the orifice.
   • the correction factor is a function of the ratio of the mass flow flowing through the orifice to the mass flow averaged over all the orifices.
   • said function is a polynomial function of the ratio between the mass flow flowing through the orifice and the mass flow averaged over all the orifices, preferably an affine function of said ratio.
   • the method further comprises a step e) of defining the distances modified in step d) as predetermined distances, the steps c) to d) being repeated at least once, preferably between 1 and 5 times, preferably 2 more times at most.
   • the mixing device comprises several first channels, the method comprising, prior to step a), at least one step of selecting a subset of orifices arranged in the same first channel, steps a) to e) being applied to said subset.

The present invention can be applied to a heat exchanger which vaporizes at least one flow of liquid-gas mixture, in particular a flow of mixture with several constituents, for example a mixture of hydrocarbons, by heat exchange with at least one another fluid, for example natural gas.

The expression “natural gas” relates to any composition containing hydrocarbons including at least methane. This includes a "raw" composition (prior to any treatment or washing), as well as any composition that has been partially, substantially or entirely treated for the reduction and/or elimination of one or more compounds, including, but not including limit, sulfur, carbon dioxide, water, mercury and certain heavy and aromatic hydrocarbons.

• la Figure 1 est une vue schématique, dans un plan de coupe parallèle aux plaques d'un échangeur de chaleur, d'une partie d'un passage d'un échangeur alimenté en mélange à deux phases liquide-gaz conformément à un mode de réalisation de l'invention;
• la Figure 2 est une vue schématique en coupe, suivant un plan perpendiculaire à celui de la Figure 1, du dispositif mélangeur de la Figure 1;
• les Figures 3 et 4 sont des vues schématiques tridimensionnelles illustrant un dispositif mélangeur selon différents modes de réalisation de l'invention ;
• les Figures 5, 6 et 7 présentent des résultats de simulations réalisées avec un dispositif mélangeur selon l'invention et avec un dispositif mélangeur hors invention.

The present invention will now be better understood thanks to the following description, given solely by way of non-limiting example and made with reference to the attached diagrams, among which:

• the Figure 1 is a schematic view, in a sectional plane parallel to the plates of a heat exchanger, of part of a passage of an exchanger fed with a two-phase liquid-gas mixture according to one embodiment of the invention;
• the Figure 2 is a schematic sectional view along a plane perpendicular to that of the Figure 1 , of the mixing device of the Figure 1 ;
• them Figure 3 and 4 are three-dimensional schematic views illustrating a mixing device according to different embodiments of the invention;
• them Figures 5, 6 and 7 present results of simulations carried out with a mixing device according to the invention and with a mixing device outside the invention.

The Figure 1 illustrates a heat exchanger 1 comprising a stack of plates 2 (not visible) which extend along two dimensions, parallel to a plane defined by a longitudinal direction z and a lateral direction y. The plates 2 are arranged parallel one above the other with spacing and thus form a plurality of passages for fluids in indirect heat exchange relation via said plates.

Preferably, each passage has a parallelepiped and flat shape. The gap between two successive plates is small compared to the length, measured along the lateral direction y, and the width, measured along the longitudinal direction z, of each passage.

The exchanger 1 can comprise a number of plates greater than 20, or even greater than 100, defining between them a first series of passages 10 to channel at least a first fluid F1, and a second series of passages 20 (not visible on the Figure 1 ) to channel at least a second fluid F2, the flow of said fluids taking place generally in the direction y. The passages 10 of the first series can be arranged, in whole or in part, alternately or adjacent to all or part of the passages 20 of the second series.

In a manner known per se, the exchanger 1 comprises distribution and evacuation means 40, 52, 45, 54, 55 configured to distribute the various fluids selectively in the passages 10, 20, as well as to evacuate said fluids from said passages 10, 20.

The sealing of the passages 10, 20 along the edges of the plates 2 is generally ensured by lateral and longitudinal sealing strips 4 fixed to the plates 2. The lateral sealing strips 4 do not completely block the passages 10, 20 but advantageously leave fluid inlet and outlet openings located at diagonally opposite corners of the passages.

The openings of the passages 10 of the first series are arranged in coincidence one above the other, while the openings of the passages 20 of the second series are arranged in the opposite corners. The openings placed one above the other are united respectively in semi-tubular manifolds 40, 45, 50, 55, through which the distribution and the evacuation of the fluids take place.

In the representation of Figure 1 , the semi-tubular collectors 50, 45 are used to introduce fluids into the exchanger 1 and the semi-tubular collectors 40, 55 are used to evacuate these fluids from the exchanger 1.

In this variant embodiment, the supply manifold for one of the fluids and the discharge manifold for the other fluid are located at the same end of the exchanger, the fluids F1, F2 thus circulating in counter-current in exchanger 1.

According to another variant embodiment, the first and second fluids can also circulate in co-current, the means for supplying one of the fluids and the means for discharging the other fluid then being located at opposite ends of the exchanger 1.

Preferably, the direction y is oriented vertically when the exchanger 1 is in operation. The first fluid F1 generally flows vertically and in the upward direction. Other directions and directions of flow of the fluids F1, F2 can of course be envisaged, without departing from the scope of the present invention.

It should be noted that in the context of the invention, one or more first fluids F1 and one or more second fluids F2 of different natures can flow within the passages 10, 20 of the first and second series of the same exchanger.

Preferably, the first fluid F1 is a refrigerant and the second fluid F2 is a circulating fluid.

The distribution and evacuation means of the exchanger advantageously comprise distribution waves 51, 54, arranged between two successive plates 2 in the form of corrugated sheets, which extend from the inlet and outlet openings. The distribution waves 51, 54 ensure the uniform distribution and recovery of fluids over the entire width of the passages 10, 20.

In addition, the passages 10, 20 advantageously comprise heat exchange structures arranged between the plates 2. The function of these structures is to increase the heat exchange surface of the exchanger and to increase the exchange coefficients between fluids by making the flows more turbulent. Indeed, the heat exchange structures are in contact with the fluids circulating in the passages and transfer heat flows by conduction to the adjacent plates 2, to which they can be fixed by brazing, which increases the mechanical resistance of the exchanger.

The heat exchange structures also have a function of spacers between the plates 2, in particular during the assembly by brazing of the exchanger and to avoid any deformation of the plates during the implementation of pressurized fluids. They also ensure the guiding of fluid flows in the passages of the exchanger.

Preferably, these structures comprise heat exchange waves 11 which advantageously extend along the width and length of the passages 10, 20, parallel to the plates 2, in the extension of the distribution waves along the length of the passages 10, 20 The passages 10, 20 of the exchanger thus have a main part of their length constituting the actual heat exchange part, which is lined with a heat exchange structure, said main part being bordered by distribution parts filled with distribution waves 51, 54.

The Figure 1 illustrates a passage 10 of the first series 1 configured to distribute a first fluid F1 in the form of a two-phase mixture, also called two-phase mixture. The first fluid F1 is separated in a separator device 6 into a first phase 61 and a second phase 62 introduced separately into the exchanger 1 via a first manifold 30 and a second manifold 50 which are distinct. The first and second phases 61, 62 are then mixed with each other by means of a mixing device 3 arranged in the passage 10. Advantageously, several passages 10, or even all of the passages 10 of the first series comprise a mixing device 3. In the case illustrated in the Figure 1 , the first phase 61 is liquid and the second phase 62 is gaseous.

The Figure 2 is a schematic sectional view, in a plane perpendicular to that of the Figure 1 , of a mixer device 3 advantageously consisting of a bar, or rod, housed in a passage 10.

The mixing device 3 preferably extends in the section of the passage 10 over almost all, or even all, of the height of the passage 10, so that the mixing device is in contact with each plate 2 forming the passage 10.

The mixing device 3 is advantageously fixed to the plates 2 by brazing.

The mixer device 3 is advantageously of generally parallelepipedal shape.

Preferably, the mixing device 3 is a monolithic part, i. e. formed in a block or in one piece. The mixing device 3 may have, parallel to the lateral direction y, a first dimension comprised between 20 and 200 mm and, parallel to the longitudinal direction z, a second dimension comprised between 100 and 1400mm.

Preferably, the first channel 31 extends over the entire second dimension and/or the second channel extends over the entire first dimension.

The mixing device 3 comprises at least a first channel 31 for the flow of the first phase 61 parallel to the longitudinal direction z and at least a second channel 32 for the flow of the second phase 62. Said first channel 31 extends parallel to the longitudinal direction z. Preferably, the first channel 31 and/or the second channel have rectilinear shapes. Preferably, the second channel 32 extends parallel to the lateral direction y which is orthogonal to the longitudinal direction z and parallel to the plates 2.

Several orifices 34 _i , 34 _i+1 ,... are distributed over the mixing device 3 so as to fluidically connect at least a first channel 31 with at least one at least a second channel 32 adapted for the flow of the second phase 62. The mixing device 3 is configured so that when the first phase 61 flows in the first channel 31 and the second phase 62 flows in the second channel 32, a two-phase liquid/gas mixture F1 is distributed at the outlet of the mixing device 3.

Preferably, the mixer device 3 comprises at least a first inlet 311 in fluid communication with the first manifold 30 and a second inlet 321, separate from the first inlet 311, in fluid communication with the second manifold 50. The first manifold 30 is connected fluidically to a first-phase source 61 and the second manifold 50 is fluidically connected to another second-phase source 62. Said at least one first inlet 311 and said at least one second inlet 321 are placed in fluid communication via the orifices 34i, 34i+1,...

Preferably, the mixing device 3 comprises a mixing volume located in the second channel 32, downstream from the orifice 34i following the flow direction of the first phase 61 in the orifice 34i. The liquid/gas two-phase mixture is distributed through a second outlet 322 of the second channel 32.

The first and second channels 31, 32 are advantageously in the form of longitudinal recesses formed in the mixer device 3.

The orifices 34 are advantageously bores 34 made in the material of the device 3 and extending between the first channel 31 and the second channel 32, preferably in the vertical direction x. Preferably, the orifices 34 are of cylindrical symmetry.

Preferably, said at least one first channel 31 comprises a bottom wall 3c and said at least one second channel comprises a top wall 3d which extends opposite the bottom wall 3c, the orifices 34 being drilled in the wall bottom of the first channel 31 and opening into the top wall of the second channel 32.

The Figure 3 is a three-dimensional view of the mixing device 3 of the Figure 2 , the Figure 2 schematizing the device 3 in a section plane orthogonal to the longitudinal direction z and passing through the orifice 34 _i .

As seen on the Figure 3 , the orifices 34 _i , 34 _i+1 ,... occupy successive positions z _i , z _i+1 ,... in the longitudinal direction z. Each orifice 34 _i , is separated from the next orifice 34 _i+1 by a distance denoted d _i , which is measured parallel to the longitudinal direction z.

In the devices according to the prior art, the orifices occupy successive positions z _i , z _{i +1} ,...located at equal distance from each other. However, the first phase 61 flows in the first channel 31 at different speeds along the longitudinal direction z and the flow rate of first phase 61 flowing in each orifice varies according to the flow speed of the first phase 61 at position z _i of the orifice considered.

In order to solve this problem, a mixer device 3 is proposed in which the distances between two successive positions z _i , z _{i +1} ,... are variable. In other words, the distances between the successive positions z _i , z _i+1 ,... are not all identical. At least one pair of successive orifices has a distance between two successive positions different from that of another pair of successive orifices.

By varying the distances between orifices in the longitudinal direction z, it is possible to compensate for the inhomogeneities of the flow rates per unit of length in the longitudinal direction z or, in other words, per unit of exchanger passage width, distributed by the orifices 34 by adapting the distribution of the orifices 34 over the width of the mixer device 3. By “flow rate per unit length”, we typically mean a flow rate distributed by an orifice, divided by the distance between this orifice and the next. For example, greater distances can be left between orifices which tend to be supercharged with first phase fluid flow 61, which will have the effect of locally reducing the flow per unit of width distributed by the orifices. In fact, it is not sought to homogenize the fluid flow which passes through each of the orifices 34 _i , 34 _i+1 ,..., by adjusting the configuration of the orifices 34 or of the first channel 31, but rather to adapt the distribution of the fluid distribution points through the orifices 34 so as to homogenize the flow rate of the first phase 61 per unit length in the longitudinal direction z.

A more homogeneous distribution of the liquid-gas mixture is thus obtained in the width of the passage 10. This solution has the advantages of being simple to implement, not to modify the size of the exchanger and not to complicate its structure.

According to one embodiment, the distances between the successive positions z _i , z _i+1 ,... vary monotonically or almost monotonically along the longitudinal direction z. In other words, the direction of variation of the successive positions z _i , z _i+1 ,... is constant or globally constant along the longitudinal direction z.

According to one embodiment, the mixer device 3 has, in the longitudinal direction z, an increase in the distances between two successive positions z _i , z _{i +1} ,.... Such a configuration is implemented when the mixer device 3 is fed in the first phase 31 by a first inlet 311, the first phase flowing in the longitudinal direction z, as illustrated in the example of Figure 3 . The orifices located on the side of the inlet 311 tend to be underfed compared to the orifices located further downstream, following the direction of flow of the first phase 61.

According to a variant embodiment (not shown), the mixer device 3 has, along the longitudinal direction z, a reduction in the distances between two successive positions z _i , z _{i +1} ,... Such a configuration is implemented when the mixing device 3 is fed in first phase 61 by a first additional inlet 312 arranged so that first phase 61 flows parallel but in a direction opposite to the longitudinal direction z.

The Figure 4 illustrates another embodiment of the invention which is particularly advantageous when the mixer device 3 has two inputs for supplying the first phase 61. More precisely, the mixer device 3 is supplied in the first phase 61 by a first input 311 and a first additional input 312. The mixer device 3 is divided, along the longitudinal direction z, into at least a first portion 301 and a second portion 302, the first portion 301 having, along the longitudinal direction z, an increase in the distances between two successive positions z _i , z _i+1 ,... and the second portion 302 presenting, according to the longitudinal direction z, a reduction in the distances between two successive positions z _i , z _i+1 ,...

This embodiment allows even better homogenization of the first phase flow 61 distributed downstream of the orifices 34 along the longitudinal direction z.

Preferably, the first inlet and the first additional inlet 311, 312 are arranged at two opposite ends of the mixing device 3. A first flow of first phase 61 is distributed by the first inlet 311 and flows in the flow direction z and a second first phase flow 61 is delivered through the first additional inlet 312 and flows parallel but in a direction opposite to the longitudinal direction z.

Advantageously, the first portion 301 is located on the side of the first inlet 311 and the second portion 302 is located on the side of the first additional inlet 312.

Preferably, the first and second portions 301, 302 are arranged symmetrically with respect to the center of the mixer device 3. Said portions could however be arranged in different numbers and have different amplitudes of variations in the distances between successive orifices on both sides. other from the center of the mixing device 3.

Advantageously, a mixing device 3 according to the invention can be configured by adjusting the position of the orifices 34 according to the steps described below. Note that all or part of these steps can be implemented by digital simulation, in particular by digital simulation of fluids (acronym CFD for Computational Fluid Dynamics in English) or by correlation of pressure drops along the first channel 31 and the orifices 34 or by actual measurements,...

An initial state of the mixer device 3 is defined in which the orifices 34 _i , 34 _i+1 ,... are arranged at successive positions z _i , z _i+1 ,... separated by predetermined distances d _i , d _i+1 ,.... Preferably, in the initial state, the predetermined distances d _i , d _i+1 ,... are identical

où d_m est la moyenne des distances prédéterminées d_i, d_i+1,... et F_i est un facteur de correction déterminé pour chaque orifice comme une fonction du débit Q_i s'écoulant à travers l'orifice 34_i.The first channel 31 is supplied so that the first phase 61 flows in the longitudinal direction z. The mass flow rates are determined Q _i , Q _i+1 ,... of the first phase 61 flowing through each orifice 34 _i , 34 _i+1 ,... of the mixing device 3 and the orifices are repositioned so that, for each orifice 34 _i , the following orifice 34 _i+1 is located from the previous orifice 34 _i at a modified distance d _i which is expressed: $${}_I=F_I\times {}_m$$

where d _m is the average of the predetermined distances d _i , d _i+1 ,... and F _i is a correction factor determined for each orifice as a function of the flow rate Q _i flowing through the orifice 34 _i .

It should be noted that preferably, in the initial state, the average distance between orifices corresponds to the identical distance separating all the orifices 34 _i , 34 _i+1 ,...

Advantageously, the correction factor F _i is a function of the ratio Q _i /Q _m between the mass flow Q _i flowing through the orifice 34 _i and the mass flow Q _m averaged over all the orifices.

où Q_i est le débit massique s'écoulant à travers l'orifice 34_i, Q_m est le débit massique moyenné sur tous les orifices, A et B sont des constantes prédéterminées en fonction des caractéristiques du dispositif mélangeur 3. Selon un mode de réalisation particulier, A=1 et/ou B=0.Preferably, this function is a polynomial function of the ratio Q _i /Q _m , more preferably an affine function of the ratio Q _i /Q _m expressed: $$F_I=\mathrm{HAS}\times \frac{Q_I}{Q_m}+B$$

where Q _i is the mass flow rate flowing through the orifice 34 _i , Q _m is the mass flow rate averaged over all the orifices, A and B are predetermined constants according to the characteristics of the mixing device 3. According to a mode of particular realization, A=1 and/or B=0.

It being specified that the adjustment method described can be applied regardless of the power supply configuration in the first phase 61 of the first channel 31 since it is in the determination of the flow rates Q _i , Q _i+1 ,...that The power configuration of the first channel 31 intervenes.

Depending on the exchange process under consideration and its sensitivity to the unequal distribution of the phases of the first fluid F1, a single step of repositioning the orifices 34 _i , 34 _i+1 ,... may suffice to homogenize the distribution of the first phase over the width of the mixing device 3.

Optionally, the step of repositioning the orifices 34 _i , 34 _i+1 ,... can be repeated at least once, preferably between 1 and 5 times, preferably even 2 times at most. The adjustment process then comprises a step of defining the distances d _i , d _i+1 ,... previously modified as predetermined distances. The new mass flow rates Q _i , Q _i+1 ,... of the first phase 61 flowing through each orifice 34 _i , 34 _i+1 ,... repositioned are determined. The average distance d _m between the orifices and the average flow rate Q _m flowing through the orifices are calculated and new modified distances d _i , d _i+1 , etc. are determined according to the expressions given previously.

In the case of a mixer device 3 with several first channels 31, the adjustment method can be carried out globally on all the first channels 31 by considering the distances d _i , d _i+1 ,... between two successive orifices, whether these orifices are arranged in the same first channel 31 or in different first channels 31.

Alternatively, the method can be carried out by considering each first channel 31 individually. To do this, optionally, the method may comprise, prior to step a), at least one step of selecting a subset of orifices 34 _i , 34 _i+1 ,... arranged in the same first channel 31, steps a) to e) being executed for said subset. At least one other subset of orifices 34 _i , 34 _i+1 ,... arranged in another first channel 31 can then be selected and steps a) to e) executed for this other subset.

In order to demonstrate the effectiveness of the invention, CFD simulations were carried out with a mixer device 3 as illustrated in the Figure 4 . A series of first three channels 31 was fed by two opposite inputs 301, 302 into a first phase 61 in the liquid state. The orifices 34 were cylindrical in shape and extended in the vertical direction x. In order to simplify the simulations, only the first phase 61 was taken into consideration, the second gaseous phase 62 being considered as having a negligible influence on the distribution of the first liquid phase 61 through each orifice 34.

The results of these simulations are presented on the Figures 5 and 6 , with a comparison between a mixing device 3 having equidistant orifices (outside the invention) and a mixing device 3 comprising a first portion 301 having, in the longitudinal direction z, an increase in the distances between two successive positions z _i , z _{i +1} ,... and the second portion 302 having, in the longitudinal direction z, a reduction in the distances between two successive positions z _i , z _i+1 ,.... (invention). The Figure 5 shows the evolution of the distances between orifices along the longitudinal direction z. In the initial state, the orifices are equidistant (outside the invention). As seen on the Figure 6 , the phenomenon of flow inhomogeneity of the first phase 61 along the longitudinal direction z is greatly reduced with a device according to the invention. Typically, the inhomogeneities of the flow rates distributed by the orifices are reduced so as to observe relative variations in flow rate between the various orifices of less than 10%.

In the context of the invention, the evolution of the distances between two successive positions zi, zi+1, etc. can be assessed in view of an evolution of the real values, measured or simulated, or of a so-called evolution "adjusted" or "smoothed" constructed from a mathematical adjustment of the real evolution of the distances between two successive positions zi, zi+1,....

Thus, the terms "increase" or "decrease" cover monotonic variations, as illustrated in the Figure 5 , or quasi-monotonic, that is to say variations which locally present, considering the real, measured or simulated values, a direction of variation different from the overall direction of variation. For example, the Picture 7 schematizes the result of a simulation leading globally to an increase in the distances between two successive positions zi, zi+1,..., but presenting for certain points a reduction in the distance between one orifice and the next. A mathematical adjustment of this evolution, represented by the dotted curve (----), results in a monotonous increase of said distances. It should be noted that depending on the case, an orifice 34 _i can be located in the same first channel 31 as the successive orifice 34 _i+1 , in particular in the case of a mixer device 3 with a single first channel 31, or in a another first channel 31. In the case of a mixer device 3 with several first channels 31, a successive orifice 34 _i+1 of a first channel 31 is preferably located in a first channel 31 other than the orifice 34 _i . The orifices 34 _i , 34 _i+1 ... are arranged at positions z _i , z _{i +1} ,..., without necessarily being arranged at the same position in the lateral direction y.

The device 3 can comprise several first channels 31 succeeding one another within the device 3 and/or several second channels 32, the first and/or the second channels 31, 32 preferably being parallel to each other.

Preferably, the first channels 31 and the second channels 32 extend parallel to the plates 2. According to the embodiment illustrated by the Figure 3 , the first channels 31 follow one another in the lateral direction y and the second channels 32 follow one another in the longitudinal direction z.

It being specified that the channels 31 and 32 can be of different or identical shapes and numbers. The distances between the first successive channels 31 and the distances between the second successive channels 32 can also vary. Preferably, the distances between the channels 32, measured along the longitudinal direction z, are adjusted according to the position of the orifices 34.

The Figures 3 to 4 represent examples of a mixer device 3 in the form of a bar, orifices 34 of cylindrical shape being drilled in the bottom of several first channels 31.

In this embodiment, the mixer device 3 generally forms a parallelepiped delimited in particular by a first surface 3a intended to be arranged facing a plate 2 of the exchanger and a second surface 3b arranged facing another plate 2 The first and second surfaces 3a, 3b preferably extend generally parallel to the plates 2. The mixing device 3 is preferably arranged in the passage 10 so that the first and second surfaces 3a, 3b are in contact with the plates 2.

Channels 31, 32 are advantageously in the form of recesses made within mixing device 3. They may or may not open out at surfaces 3a and/or 3b.

The orifices 34 are advantageously bores 34 made in the material of the device 3 and extending between the first channel 31 and the second channel 32, preferably in the vertical direction x. Preferably, the orifices 34 are of cylindrical symmetry.

Note that the orifices 34 _i , 34 _i+1 ,... do not necessarily have the same shape or the same dimensions. The number of different shapes, the sizing and the distribution of the orifices, in the same first channel 31 or between several first channels 31, may vary depending on the distribution of liquid-gas mixture desired, so as to adapt the flow rate even more finely. of fluid in the orifices 34. In particular, in the case of a first channel with an inlet 311, it is possible to arrange orifices of larger sections upstream of the first channel 31, where the speed of the first phase 61 is the larger, and lower inlet section orifices downstream of the first channel 31. The shape, the dimensions of the first and/or second channels 31, 32 can also vary along the y and/or z directions and from one channel 31, 32 to another

Of course, the invention is not limited to the specific examples described and illustrated in the present application. Other variants or embodiments within the reach of those skilled in the art can also be envisaged without departing from the scope of the invention.

For example, the exchanger according to the invention is mainly described in the case where the passages 10, 20 extend along the lateral direction y, the first longitudinal channel 31 extending along the flow direction z and the lateral channel 32 extending along the lateral direction y orthogonal to the z direction. The reverse is also possible, for example a first longitudinal channel 31 extending along the lateral direction y and a lateral channel 32 extending along the flow direction z. The y and z directions may also not be orthogonal to each other.

Claims (16)

1. Heat exchanger (1) comprising several plates (2) arranged parallel to one another and to a longitudinal direction (z) so as to define a plurality of passages (10) for channelling at least a first fluid (F1) which is to be brought into a heat-exchange relationship with at least a second fluid (F2), a mixer device (3) being arranged in at least one passage (10) and comprising:

   - at least one first channel (31) for the flow of a first phase (61) of the first fluid (F1) parallel to the longitudinal direction (z),

   - at least one second channel (32) for the flow of a second phase (62) of the first fluid (F1), and

   - a plurality of orifices (34_i, 34_i+1,...) fluidically connecting the first channel (31) to the second channel (32), said orifices (34_i, 34_i+1,...) occupying successive positions (z_i, z_i+1,...) in the longitudinal direction (z), characterized in that the distances between the successive positions (z_i, z_i+1, ...), measured parallel to the longitudinal direction (z), are variable.
2. Exchanger according to Claim 1, characterized in that the distances between the successive positions (z_i, z_i+1,...) vary monotonically or near-monotonically in the longitudinal direction (z).
3. Exchanger according to one of Claims 1 and 2, characterized in that it exhibits, in the longitudinal direction (z), an increase in the distances between two successive positions (z_i, z_i+1,...).
4. Exchanger according to one of Claims 1 and 2, characterized in that it exhibits, in the longitudinal direction (z), a decrease in the distances between two successive positions (z_i, z_i+1,...).
5. Exchanger according to Claim 1, characterized in that it is divided, in the longitudinal direction (z), into at least a first portion (301) and a second portion (302), the first portion (301) exhibiting, in the longitudinal direction (z), an increase in the distances between two successive positions (z_i, z_i+1,...), and the second portion (302) exhibiting, in the longitudinal direction (z), a decrease in the distances between two successive positions (z_i, z_i+1,...).
6. Exchanger according to one of the preceding claims, characterized in that the mixer device (3) is configured for a separate introduction of the first phase (61) and of the second phase (62) into the at least one first channel (31) and into the at least one second channel (32), respectively, the first channel (31) comprising a first inlet (311) designed to supply said first channel (31) with the first phase (61) of the first fluid (F1) and a second inlet (321), separate from the first inlet (311), designed to supply said at least one second channel (32) with the second phase (62) of the first fluid (F1).
7. Exchanger according to one of the preceding claims, characterized in that the first channel (31) and the second channel (32) are rectilinear in shape.
8. Exchanger according to one of the preceding claims, characterized in that the mixer device (3) comprises several first channels (31) and several second channels (32), each first channel (31) comprising at least one orifice (34_i, 34_i+1,...) fluidically connecting said first channel (31) to a given second channel (32).
9. Exchanger according to one of the preceding claims, characterized in that the mixer device (3) comprises several first channels (31) succeeding one another in a lateral direction (y) orthogonal to the longitudinal direction (z).
10. Exchanger according to one of the preceding claims, characterized in that the second channel (32) extends in a lateral direction (y) orthogonal to the longitudinal direction (z).
11. Method for distributing a two-phase liquid/gas mixture in an exchanger according to one of Claims 1 to 10, said method comprising the following steps:

    i) arranging a mixer device (3) in at least one passage (10) of the exchanger,

    ii) supplying said first channel (31) of the mixer device (3) with the first phase (61) of the first fluid (F1),

    iii) supplying said second channel (32) of the mixer device (3) with the second phase (62) of the first fluid (F1), which is distinct from the first phase (61),

    iv) establishing fluidic communication between the first channel (31) and the second channel (32) via the orifices (34_i, 34_i+1,...) so that a mixing between the first phase (61) and the second phase (62) takes place within the mixer device (3), and
    distributing a mixture of the first phase (61) and of the second phase (62) at the outlet of the mixer device (3).
12. Method for adjusting the position of the orifices (34) of a mixer device (3) incorporated into an exchanger according to one of Claims 1 to 8, said method comprising the following steps:

    a) positioning the orifices (34_i, 34_i+1,...) in such a way that their successive positions (z_i, z_i+1,...) are separated by predetermined distances (d_i, d_i+1,...),

    b) supplying the first channel (31) with the first phase (61) of the fluid (F1) such that the first phase (61) of the first fluid (F1) flows in the longitudinal direction (z),

    c) determining the mass flow rates (Q_i, Q_i+1,...) of the first phase (61) flowing through each orifice (34_i, 34_i+1,...),

    d) for each orifice (34_i), repositioning the next orifice (34_i+1) so that it is separated from the orifice (34_i) by a modified distance (d_i) equal to the mean (d_m) of the predetermined distances (d_i, d_i+1,...) multiplied by a correction factor (F_i), said correction factor being determined on the basis of the mass flow rate (Q_i) flowing through the orifice (34_i).
13. Method according to Claim 12, characterized in that the correction factor (F_i) is a function of the ratio (Q_i/Q_m) between the mass flow rate (Q_i) flowing through the orifice (34_i) and the mass flow rate (Q_m) averaged over all the orifices.
14. Method according to Claim 13, characterized in that said function is a polynomial function of the ratio (Q_i/Q_m), preferably an affine function of the ratio (Q_i/Q_m).
15. Method according to one of Claims 10 to 14, characterized in that it further comprises a step e) of defining the distances (d_i, d_i+1,...) modified in step d) as predetermined distances, steps c) to d) being reiterated at least once, preferably between 1 and 5 times, more preferably at most twice.
16. Method according to one of Claims 10 to 15, characterized in that the mixer device (3) comprises several first channels (31), the method comprising, prior to step a), at least one step of selecting a subset of orifices (34_i, 34_i+1,...) which are arranged in one and the same first channel (31), steps a) to e) being applied to said subset.

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