WO2019180384A1

WO2019180384A1 - Heat exchanger with improved liquid/gas mixing device

Info

Publication number: WO2019180384A1
Application number: PCT/FR2019/050642
Authority: WO
Inventors: Marine ANDRICH; Natacha Haik-Beraud; Philippe Grigoletto; Jean-Marc Peyron; Ahlem DELEGUE
Original assignee: L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude
Priority date: 2018-03-22
Filing date: 2019-03-21
Publication date: 2019-09-26
Also published as: FR3079291B1; FR3079291A1; JP2021517232A; US20200408466A1; EP3769024A1; JP7309739B2; EP3769024B1

Abstract

The invention relates to a heat exchanger (1) comprising a plurality of plates (2) arranged in parallel and in a longitudinal direction (z) so as to define a first series of passages (10) for channelling at least one first fluid (F1) and a second series of passages (20) for channelling at least one second fluid (F2) which is to be brought into a heat-exchanging arrangement with at least said first fluid (F1), a mixing device (3) being provided in said at least one passage (10) of the first series and comprising at least one first channel (31) for the flow of a first phase (61) of the fluid (F1) in the longitudinal direction (z), at least one second channel (32) for the flow of a second phase (62) of the fluid (F1), and a plurality of openings (34i, 34i+1, ...) establishing fluid connection between the first channel (31) and the second channel (32), said openings (34i, 34i+1, ...) occupying consecutive positions (zi, zi+1, ...) in the longitudinal direction (z). According to the invention, the distances between two consecutive positions (zi, zi+1, ...), measured parallel to the longitudinal direction (z), are variable.

Description

HEAT EXCHANGER WITH MIXER DEVICE

IMPROVED LIQUID / GAS

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

In particular, the present invention can be applied to a heat exchanger which vaporizes at least one liquid-gas mixture flow rate, in particular a multi-component mixing flow rate, for example a hydrocarbon mixture, by heat exchange with at least one other fluid, for example natural gas.

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

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

In order to ensure the proper functioning of a heat exchanger using a liquid-gas mixture, the proportion of liquid phase and gas phase must be the same in all the passages and must be uniform within the same passage.

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

For a multi-component mixture, the end-of-vaporization temperature will depend on the proportion of liquid phase and gas phase in the passages. In the case of 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. Due to this non-uniform distribution, it may then happen that the fluid or fluids in exchange relationship with the two-phase mixture have a temperature at the outlet of the exchanger greater than that expected, thereby degrading the performance of the heat exchanger.

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

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 problem that 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 to 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 rate decreases as the ports are energized.

However, the orifices are generally machined perpendicularly to the direction of flow of the fluid and are therefore less well fed when the fluid velocity is greater. The orifices arranged on the side of the inlet of the channel therefore tend to be underfed, while the orifices located at the bottom of the channel are supercharged. It follows an unequal introduction of the phase considered in the channel for the other phase, and thence an unequal 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 feed the channel considered by two opposite inputs of the channel. However, it follows a complexification of the exchanger and the problem of the 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 soldering of the device.

Another known solution is to have cylindrical orifices having different diameters along the channel. However, this solution may be insufficient for some processes.

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

The solution according to the invention is then a heat exchanger comprising a plurality of plates arranged parallel to each other and in a longitudinal direction so as to define a plurality of passages for channeling at least one fluid to be in heat exchange relationship with at least one other fluid. , a mixing device being arranged in at least one passage and comprising:

at least one 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 fluidly connecting the first channel to the second channel, said orifices occupying successive positions in the longitudinal direction,

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

Depending on the case, the exchanger of the invention may include one or more of the following technical characteristics: the distances between the successive positions vary in a monotonic or quasi-monotonic manner 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 decrease in 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 having, in the longitudinal direction, an increase in distances between two successive positions and the second portion having, in the direction longitudinal, a decrease in distances between two successive positions.

the mixing device is configured for 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 supply said first channel with the first phase of the first fluid and a second input, separate from the first input, adapted to supply said at least one second channel in the second phase of the first fluid.

the first channel and / or the second channel are rectilinear.

the mixing device comprises a first inlet and a first additional inlet adapted to feed the at least one first channel into the first phase of the fluid, the first portion being situated on the side of the first inlet and the second portion being located on the side of the first inlet; first additional entry.

- The mixing device comprises a plurality of first channels and a plurality of second channels, each first channel comprising at least one orifice fluidly connecting said first channel to a second channel.

- The mixing device comprises a plurality of first channels succeeding in a lateral direction orthogonal to the longitudinal direction.

the second channel extends in a lateral direction orthogonal to the longitudinal direction. In addition, the invention relates to a method for dispensing a two-phase liquid / gas mixture in an exchanger according to the invention, said method comprising the following steps:

i) arranging a mixing device in at least one passage of the exchanger,

ii) supplying said first channel of the mixing device with the first phase of the first fluid,

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), iv) putting in fluid communication the first channel with the second channel via the orifices so that a mixture between the first phase and the second phase takes place within the mixing device, and

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

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

a) positioning the orifices so that their successive positions are separated by predetermined distances,

b) feeding the first channel in the first phase of the fluid so that the first phase of the fluid flows in the longitudinal direction, c) determining the mass flow rates of the first phase flowing through each orifice,

d) for each orifice, repositioning the next orifice so that it is separated from the orifice by a modified distance equal to the average of the predetermined distances multiplied by a correction factor, said correction factor being determined according to mass flow flowing in the orifice.

the correction factor is a function of the ratio between the mass flow rate flowing through the orifice and the mass flow rate averaged over all the orifices. said function is a polynomial function of the ratio between the mass flow rate flowing through the orifice and the mass flow rate 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, of more preferably 2 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, the steps a) to e) being applied to said subset.

The present invention can be applied to a heat exchanger which vaporizes at least one liquid-gas mixture flow rate, in particular a multi-component mixture flow rate, for example a hydrocarbon mixture, by heat exchange with at least one other fluid, for example natural gas.

The term "natural gas" refers to any composition containing hydrocarbons including at least methane. This includes a "raw" composition (prior to any treatment or wash), as well as any composition that has been partially, substantially, or wholly processed for the reduction and / or elimination of one or more compounds, including but not limited to limit, sulfur, carbon dioxide, water, mercury and some heavy and aromatic hydrocarbons.

The present invention will now be better understood thanks to the following description, given solely by way of nonlimiting example and with reference to the attached drawings, among which:

FIG. 1 is a diagrammatic view, in a plane of section parallel to the plates of a heat exchanger, of part of a passage of a heat exchanger fed with a two-phase liquid-gas mixture in accordance with one embodiment of the invention; of the invention;

Figure 2 is a schematic sectional view, in a plane perpendicular to that of Figure 1, of the mixing device of Figure 1; Figures 3 and 4 are three-dimensional schematic views illustrating a mixing device according to different embodiments of the invention;

Figures 5, 6 and 7 show results of simulations performed with a mixing device according to the invention and with a mixing device outside the invention.

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

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

The exchanger 1 may comprise a number of plates greater than 20, or even greater than 100, defining between them a first series of passages 10 for channeling at least a first fluid F1, and a second series of passages 20 (not visible in FIG. 1) for channeling at least one second fluid F2, the flow of said fluids occurring generally in the y direction. The passages 10 of the first series may be arranged wholly or partly, 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 different fluids selectively in the passages 10, 20, as well as for discharging said fluids from said passages. 10, 20.

The tightness 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 close the passages 10, 20 but advantageously leave fluid inlet and outlet openings in the diagonally opposite corners of the passages.

The openings of the passages 10 of the first series are arranged coincidentally 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 joined respectively in collectors of semi-tubular form 40, 45, 50, 55, through which the distribution and evacuation of the fluids take place.

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

In this embodiment, the supply manifold of one of the fluids and the exhaust manifold of the other fluid are located at the same end of the exchanger, the fluids F1, F2 thus flowing against the flow in the exchanger 1.

According to another variant embodiment, the first and second fluids can also flow cocurrently, the supply means for one of the fluids and the means for discharging the other fluid then being located at opposite ends of the fluid. exchanger 1.

Preferably, the direction is oriented vertically when the exchanger 1 is in operation. The first fluid F1 flows globally vertically and in the ascending direction. Other directions and direction of flow of fluids F1, F2 are of course conceivable, 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 the recovery of the 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. These structures have the function of increasing the heat exchange surface of the exchanger and to increase the exchange coefficients between fluids by making the flow more turbulent. In fact, 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 soldering, which increases the mechanical strength of the exchanger.

The heat exchange structures also have a function of spacers between the plates 2, in particular during assembly by brazing of the exchanger and to prevent any deformation of the plates during the implementation of fluids under pressure. They also guide the flow of fluid in the passages of the exchanger.

Preferably, these structures comprise heat exchange waves 11 which advantageously extend along the width and the 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 portion of their length constituting the heat exchange portion proper, which is lined with a heat exchange structure, said main part being bordered by distribution parts filled with distribution waves 51, 54.

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 separate. The first and second phases 61, 62 are then mixed one with the other by means of a mixing device 3 arranged in the passage 10. Advantageously, several passages 10, or even all the passages 10 of the first series comprises a mixing device 3. In the case illustrated in FIG. 1, the first phase 61 is liquid and the second phase 62 is gaseous.

FIG. 2 is a diagrammatic sectional view, in a plane perpendicular to that of FIG. 1, of a mixing 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, indeed 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 soldering.

The mixing device 3 is advantageously of parallelepipedal general shape.

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

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 one first channel 31 for the flow of the first phase 61 parallel to the longitudinal direction z and at least one 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 ,, 34i _{+ i} , ... are distributed on the mixing device 3 so as to connect fluidically at least one first channel 31 with minus 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 mixing device 3 comprises at least a first inlet 31 1 in fluid communication with the first collector 30 and a second inlet 321, separated from the first inlet 31 1, in fluid communication with the second collector 50. The first collector 30 is fluidly connected to a first phase source 61 and the second collector 50 is fluidly connected to another second phase source 62. Said at least a first input 31 1 and said at least one second input 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 of the orifice 34i following the direction of flow of the first phase 61 in the orifice 34i. The two-phase liquid / gas 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 mixing device 3.

The orifices 34 are advantageously holes 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 cylindrically symmetrical.

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 facing the bottom wall 3c, the orifices 34 being pierced in the wall bottom of the first channel 31 and opening into the top wall of the second channel 32.

Figure 3 is a three-dimensional view of the mixing device 3 of Figure 2, Figure 2 schematically showing the device 3 in a cutting plane orthogonal to the longitudinal direction z and passing through the orifice 34 ,. As seen in Figure 3, the orifices 34 ,, 34i _{+ i} , ... occupy successive positions z · ,, Zi + i,. . . along the longitudinal direction z. Each orifice 34 ,, is separated from the next orifice 34, ₊ i by a distance d, which is measured parallel to the longitudinal direction z.

In the devices according to the prior art, the orifices occupy successive positions z ·, z, ₊ i, ... located equidistant from one another. However, the first phase 61 flows in the first channel 31 at different speeds along the longitudinal direction z and the first phase flow 61 flowing in each orifice varies according to the flow rate of the first phase 61 at the position z, of the orifice considered.

In order to solve this problem, there is provided a mixing device 3 in which the distances between two successive positions z · ,, Zi _{+ i} , ... are variable. In other words, the distances between the successive positions z ,, Zi _{+ i} , ... 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 the orifices in the longitudinal direction z, it is possible to compensate for inhomogeneities of flow rates per unit of length in the longitudinal direction z or, otherwise, per unit of heat exchanger passage width, distributed through the orifices. 34 by adapting the distribution of the orifices 34 over the width of the mixing device 3. By "flow per unit length" is typically meant a flow dispensed through an orifice, divided by the distance between this orifice and the next. For example, greater distances can be left between orifices that tend to be supercharged at first phase fluid flow rate 61, which will locally reduce the flow rate per unit of width distributed through the orifices. In fact, it is not sought to homogenize the fluid flow that passes through each of orifices 34 ,, 34, ₊ i, ..., adjusting the configuration of orifices 34 or first channel 31, but rather to adjust the distribution of fluid distribution points through the orifices 34 so as to homogenize the first phase flow rate 61 per unit length in the longitudinal direction z.

This gives a more homogeneous distribution of the liquid-gas mixture in the width of the passage 10. This solution has the advantages of being simple implementation, not to change the size of the exchanger and not to complicate its structure.

According to one embodiment, the distances between the successive positions z · ,, Zi + i,. .. vary monotonically or near-monotonically in the longitudinal direction z. In other words, the direction of variation of the successive positions z · ,, Zi + i,. .. is constant or generally constant along the longitudinal direction z.

According to one embodiment, the mixing device 3 has, in the longitudinal direction z, an increase in the distances between two successive positions z ,, Zi + i,. .. Such a configuration is implemented when the mixing device 3 is fed in first phase 31 by a first input 311, the first phase flowing in the longitudinal direction z, as illustrated in the example of FIG. on the input side 311 tending to be underfed with respect to the further downstream orifices, following the direction of flow of the first phase 61.

According to an alternative embodiment (not shown), the mixing device 3 has, in the longitudinal direction z, a decrease in the distances between two successive positions z ,, Zi + i,. 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 the first phase 61 flows parallel but in a direction opposite to the longitudinal direction z.

FIG. 4 illustrates another embodiment of the invention that is particularly advantageous when the mixing device 3 has two inputs for feeding in the first phase 61. More specifically, the mixing device 3 is fed in first phase 61 by a first inlet 31 1 and a first additional inlet 312. The mixing device 3 is divided, in the longitudinal direction z, into at least a first portion 301 and a second portion 302, the first portion 301 having, in the longitudinal direction z, an increase in the distances between two successive positions z ,, Zi + i,. .. and the second portion 302 presenting, following the longitudinal direction z, a decrease of the distances between two successive positions z · ,, z _{l + i} , ...

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 31 1, 312 are arranged at two opposite ends of the mixing device 3. A first first phase flow 61 is distributed by the first inlet 31 1 and flows in the direction of z flow and a second first-phase flow 61 is distributed by 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 31 1 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 mixing device 3. Said portions could, however, be arranged in a different number and have amplitudes of variations in the distances between successive successive orifices on each side. other of 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 numerical simulation, in particular by numerical fluid simulation (acronym CFD for Computational Fluid Dynamics in English) or by correlation of pressure losses along the first channel 31 and orifices. 34 or by real measures, ...

An initial state of the mixing device 3 is defined in which the orifices 34 ,, 34i _{+ i} , ... are arranged at successive positions ¾, Zi + i,. . . separated by predetermined distances d ,, di _{+ i} , .... Preferably, in the initial state, the predetermined distances di, di _{+ i} , ... are identical

The first channel 31 is powered so that the first phase 61 flows in the longitudinal direction z. Mass flow rates are determined Qi, Qi + i, ... of the first phase 61 flowing through each orifice 34 ,, 34i _{+ i} , ... of the mixing device 3 and repositioning the orifices so that, for each orifice 34 ,, the orifice 34, ₊ i following is from the previous orifice 34, at a modified distance d, which is expressed:

di Ei xd _m

where d _m is the average of the predetermined distances di, di _{+ i} , ... and F, is a correction factor determined for each orifice as a function of the flow Qi flowing through the orifice 34,.

Note that preferably, in the initial state, the mean distance between orifices corresponds to the identical distance separating all the orifices 34 ,, 34i _{+ i} , ...

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

Preferably, this function is a polynomial function of the ratio Qi / Q _m , more preferably an affine function of the ratio Qi / Q _m expressing:

where Qi is the mass flow rate flowing through the orifice 34 ,, Q _m is the mass flow rate averaged over all the orifices, A and B are predetermined constants as a function of the characteristics of the mixing device 3. According to one embodiment in particular, A = 1 and / or B = 0.

It being specified that the adjustment method described can be applied irrespective of the first phase power supply configuration 61 of the first channel 31 since it is in the determination of the rates Qi, Qi _{+ i} , ... that occurs the power configuration of the first channel 31.

According to the exchange method considered and its sensitivity to the unequal distribution of the phases of the first fluid F1, a single step of repositioning the orifices 34 ,, 34i _{+ i} , ... may be sufficient to homogenize the distribution of the first phase on the width of the mixing device 3.

Optionally, the step of repositioning orifices 34 ,, 34i _{+ i} , ... may be repeated at least once, preferably between 1 and 5 times, more preferably 2 times at most. The adjustment process then comprises a step of defining the distances di, di _{+ i} , ... previously modified as predetermined distances. The new mass flow rates Qi, Qi + i, ... of the first phase 61 flowing through each orifice 34 ,, 34i _{+ i} , ... repositioned are determined. The average distance d _m between the orifices and the average flow Q _m flowing through the orifices is calculated and new modified distances di, di _{+ i} , ... 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 conducted globally on all the first channels 31 by considering the distances di, di _{+ i} , ... between two orifices. successive, that these orifices are arranged in the same first channel 31 or in first different channels 31.

Alternatively, the method may be conducted 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 ,, 34i _{+ i} , ... arranged in the same first channel 31, steps a) to e) being performed for said subset. At least another subset of orifices 34 ,, 34i _{+ i} , ... arranged in another first channel 31 can then be selected and steps a) to e) performed for this other subset.

In order to demonstrate the effectiveness of the invention, CFD simulations were carried out with a mixing device 3 as illustrated in FIG. 4. A series of first three channels 31 was fed by two opposite inputs 301, 302 in a first phase 61 in the liquid state. The orifices 34 were of cylindrical 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 by each orifice 34.

The results of these simulations are shown in FIGS. 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 distances between two successive positions z · ,, Zi + i,. . . and the second portion 302 having, in the longitudinal direction z, a decrease in distances between two successive positions z · ,, z _{l + i} , .... (invention). Figure 5 shows the evolution of the distances between orifices in the longitudinal direction z. In the initial state, the orifices are equidistant (except invention). As seen in Figure 6, the flow inhomogeneity phenomenon 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 less than 10%.

In the context of the invention, the evolution of the distances between two successive positions zi, zi + 1, ... can be assessed in the light 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 actual evolution of the distances between two successive positions zi, zi + 1, ....

Thus, the terms "increase" or "decrease" cover monotonic variations, as illustrated in Figure 5, or quasi-monotone, that is to say, variations that present locally, considering the actual values, measured or simulated, a direction of variation different from the direction of global variation. For example, FIG. 7 schematizes the result of a simulation generally leading to an increase in the distances between two successive positions zi, zi + 1, ..., but presenting for certain points a decrease in the distance between one orifice and the next . A mathematical adjustment of this evolution, represented by the dashed curve (-), results in a monotonous increase in said distances. Note that, as the case may be, an orifice 34 may be in the same first channel 31 as the successive orifice 34i _{+ 1} , in particular in the case of a single-channel mixing device 3 with the first channel 31, or in another first channel 31. In the case of a mixer device 3 with several first channels 31, a successive orifice 34, _{+ i} of a first channel 31 is preferably in another first channel 31 that the orifice 34,. The orifices _34, 34, _{i +} ... are arranged at positions · z ,, z, _{+ i,} ..., without necessarily being arranged at a same position in the lateral direction Y The device 3 may comprise several first channels 31 succeeding each other within the device 3 and / or several second channels 32, the first and / or the second channels 31, 32 being preferably 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 in FIG. 3, the first channels 31 follow each other in the lateral direction y and the second channels 32 follow one another following the longitudinal direction z.

It being specified that the channels 31 and 32 may be of a shape and in distinct or identical numbers. The distances between the first successive channels 31 and the distances between the second successive channels 32 may also vary. Preferably, the distances between the channels 32, measured in the direction of the longitudinal direction z, are adjusted as a function of the position of the orifices 34.

Figures 3 to 4 show examples of mixer device 3 in the form of a bar, holes of cylindrical shape being pierced in the bottom of several first channels 31.

In this embodiment, the mixing device 3 generally forms a parallelepiped delimited in particular by a first surface 3a intended to be arranged opposite a plate 2 of the exchanger and a second surface 3b arranged opposite 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.

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

The orifices 34 are advantageously holes 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 cylindrically symmetrical. Note that the orifices 34 ,, 34, ₊ i, ... do not necessarily have the same shape or the same dimensions. The number of different shapes, the dimensioning and distribution of the orifices, in the same first channel 31 or between several first channels 31, may vary depending on the desired liquid-gas mixture distribution, so as to further fine-tune the flow rate In particular, in the case of a first channel with an inlet 31 1, it will be possible to arrange orifices of larger sections upstream of the first channel 31, where the speed of the first phase 61 is the largest, and lower inlet section ports downstream of the first channel 31. The shape, the dimensions of the first and / or second channels 31, 32 may also vary along the directions y and / or z and from one channel 31, 32 to another

Of course, the invention is not limited to the particular 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 in the lateral direction y, the first longitudinal channel 31 extending in the direction of flow z and the lateral channel 32 extending in the lateral direction y orthogonal to the direction z. The opposite is also conceivable, for example a first longitudinal channel 31 extending in the lateral direction y and a lateral channel 32 extending in the direction of flow z. The directions y and z may also not be orthogonal to each other.

Claims

1. Heat exchanger (1) comprising a plurality of plates (2) arranged parallel to each other and in a longitudinal direction (z) so as to define a plurality of passages (10) for channeling at least one first fluid (F1) to be put into exchange relation thermal device with at least a second fluid (F2), a mixing 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

- several orifices (34, 34, ₊ i, ...) fluidly connecting the first channel (31) to the second channel (32), said orifices (34 ,, 34i _{+ i} , ...) occupying successive positions ( z ,, Zi + i, ...) in the longitudinal direction (z),

characterized in that the distances between the successive positions (z ,, Zi + i, ...), 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 ,, Zi + i, ... ..) vary monotonically or quasi-monotonically in the longitudinal direction (z).

3. Exchanger according to one of claims 1 or 2, characterized in that it has, in the longitudinal direction (z), an increase in the distances between two successive positions (¾, z, ₊ i, ...).

4. Exchanger according to one of claims 1 or 2, characterized in that it has, in the longitudinal direction (z), a decrease in distances between two successive positions (¾, z, ₊ i, ...).

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) having, in the longitudinal direction (z), an increase in the distances between two successive positions (¾, Zi + i, ...) and the second portion (302) having, in the longitudinal direction (z), a decrease in the distances between two successive positions (z ,, z, ₊ i, ...).

Exchanger according to one of the preceding claims, characterized in that the mixing device (3) is configured for separate introduction of the first phase (61) and the second phase (62) into the at least one first channel ( 31) and in the at least one second channel (32) respectively, the first channel (31) comprising a first input (31 1) adapted to supply said first channel (31) in the first phase (61) of the first fluid (F1 ) and a second input (321), separate from the first input (31 1), adapted to supply said at least one second channel (32) in 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 of rectilinear shape.

8. Exchanger according to one of the preceding claims, characterized in that the mixing device (3) comprises a plurality of first channels (31) and a plurality of second channels (32), each first channel (31) comprising at least one orifice (34, , 34i _{+ i} , ...) fluidly connecting said first channel (31) to a second channel (32).

9. Exchanger according to one of the preceding claims, characterized in that the mixing device (3) comprises a plurality of first channels (31) succeeding 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. A method of dispensing 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 mixing device (3) in at least one passage (10) of the exchanger,

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

iii) supplying said second channel (32) of the mixing device (3) in the second phase (62) of the first fluid (F1) distinct from the first phase (61),

iv) placing in fluid communication the first channel (31) with the second channel (32) via the orifices (34i, 34i + 1, ...) so that a mixture between the first phase (61) and the second phase (62) takes place within the mixing device (3), and

distributing a mixture of the first phase (61) and the second phase (62) at the outlet of the mixing device (3).

12. A method of adjusting the position of the orifices (34) of a mixing device (3) integrated in an exchanger according to one of claims 1 to 8, said method comprising the following steps:

a) positioning the orifices (34 ,, 34, ₊ i, ...) so that their successive positions (¾, Zi + i, ...) are separated by predetermined distances (di, di + i, . ..),

b) feeding the first channel (31) in the first phase (61) of the fluid (F1) so that the first phase (61) of the first fluid (F1) flows in the longitudinal direction (z),

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

d) for each orifice (34,), repositioning the next orifice (34i _{+ i} ) so that it is separated from the orifice (34,) by a modified distance (d,) equal to the average ( d _m ) predetermined distances (di, di _{+ i} , ...) multiplied by a correction factor (F), said correction factor being determined as a function of the mass flow rate (Q i) flowing in the orifice (34).

Method according to claim 12, characterized in that the correction factor (F,) is a function of the ratio (Qi / Q _m ) between the mass flow rate (Q,) flowing through the orifice (34, ) and the mass flow (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 (Qi / Q _m ), preferably an affine function of the ratio (Qi / 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 (di, di _{+ i} , ...) modified in step d) as predetermined distances, steps c) to d) being repeated at least once, preferably between 1 and 5 times, more preferably 2 times at most.

16. Method according to one of claims 10 to 15, characterized in that the mixing device (3) comprises a plurality of first channels (31), the method comprising, prior to step a), at least one step of selection of a subset of orifices (34 ,, 34i _{+ i} , ...) arranged in the same first channel (31), the steps a) to e) being applied to said subset.