FR3060729A1 - HEAT EXCHANGER WITH THERMAL INSULATING CHANNEL LIQUID / GAS MIXING DEVICE - Google Patents

Abstract

Heat exchanger (1) with plates (2a, 2b, 2c, ...) defining a first series of passages (10) for channeling at least one refrigerant (F1) and a second series of passages (20) for channeling at at least one heat transfer fluid (F2), at least one passage (10) of the first series being defined between a first plate (2a) defining an adjacent passage (20) of the second series and a second plate (2b). A mixing device (3) is arranged in the passage (10) of the first series and comprises at least a first channel (31) for channeling a gaseous phase (61) of the refrigerant (F1) and at least one second channel (32). ) for channeling a liquid phase (62) of the refrigerant (F1), said first channel (31) and second channel (32) extending parallel to the first and second plates (2a, 2b). According to the invention, the mixing device (3) further comprises at least one second longitudinal channel (37) arranged between the second channel (32) and the second plate (3b) and extending parallel to said second plate (2b) .

Description

Holder (s): AIR LIQUIDE, ANONYMOUS COMPANY FOR THE STUDY AND EXPLOITATION OF GEORGES CLAUDE PROCESSES Société anonyme.

Extension request (s)

Agent (s): AIR LIQUIDE.

FR 3 060 729 - A1 (04) HEAT EXCHANGER WITH THERMAL DEVICE.

©) Heat exchanger (1) with plates (2a, 2b, 2c, ...) defining a first series of passages (10) for channeling at least one refrigerant (F1) and a second series of passages (20) for channeling at least one circulating fluid (F2), at least one passage (10) of the first series being defined between a first plate (2a) defining an adjacent passage (20) of the second series and a second plate (2b). A mixing device (3) is arranged in the passage (10) of the first series and comprises at least a first channel (31) for channeling a gas phase (61) of the refrigerant (F1) and at least a second channel (32 ) for channeling a liquid phase (62) of the refrigerant (F1), said first channel (31) and second channel (32) extending parallel to the first and second plates (2a, 2b). According to the invention, the mixing device (3) further comprises at least one second longitudinal channel (37) arranged between the second channel (32) and the second plate (3b) and extending parallel to said second plate (2b) .

CHANNEL LIQUID / GAS MIXER

INSULATING

The present invention relates to a heat exchanger comprising series of passages for each of the fluids to be put into heat exchange relation, the exchanger comprising at least one mixing device configured to distribute at least one mixture with two liquid / gas phases in a series of passages.

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

In order to ensure the proper functioning of an exchanger implementing 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 by assuming a uniform distribution of the phases, and therefore a single end temperature of vaporization of the liquid phase, equal to the dew temperature of the mixture.

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

In the case of an uneven distribution of the two phases, the temperature profile of the refrigerant will therefore vary according to the passages, or even vary within the same passage. Due to this non-uniform distribution, it can then happen that the circulating 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 heat exchanger.

One solution for distributing the liquid and gaseous phases of the mixture as uniformly as possible consists in introducing them separately into the exchanger, 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 has separate inputs for a liquid phase and a gas phase opening into a common mixing volume provided with an outlet for distributing the liquid-gas mixture to the heat exchange zone.

However, the liquid phase supplying the mixing device is then inevitably in a heat exchange situation with the circulating fluid or fluids circulating in the adjacent passages of the other series of passages. This can lead to the start of vaporization of the liquid phase within the corresponding inlets, thereby causing an uneven distribution of the two phases of the mixture in certain passages of the series as well as in certain zones within the same passage.

In order to minimize the heat exchanges that can occur at the level of the mixing device, one solution would be to install the mixing device in an area of the exchanger in which no other fluid circulates. It would then be necessary to place the mixing device at one end of the exchanger, free from any means of evacuation or supply of fluid, which would require restructuring the exchanger as a whole and would necessarily lead to increasing its size. In addition, such a solution does not allow the introduction of the two-phase mixture in the middle of the exchanger, which may be desirable in cases where the specifics of the process require it.

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, without complicating excessively the structure of the exchanger, nor increase its size.

The solution according to the invention is then a heat exchanger comprising several plates arranged parallel to each other so as to define a first series of passages for channeling at least one refrigerant and a second series of passages for channeling at least one circulating fluid to be put in heat exchange relation with at least said refrigerant, at least one passage of the first series being defined between a second plate defining an adjacent passage of the second series and a first plate, a mixing device being further arranged in said at minus one passage from the first series and comprising:

- at least a first channel for channeling a gaseous phase of the refrigerant,

- At least a second channel for channeling a liquid phase of the refrigerant, said first channel and second channel extending parallel to the first and second plates, characterized in that the mixing device further comprises at least a third channel for channeling the phase gaseous refrigerant F1, said third channel extending parallel to said second plate and being arranged between the second channel and the second plate.

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

- The first channel is arranged between the second channel and the first plate.

- the first and third channels extend in the same longitudinal direction.

- the second channel extending in a lateral direction orthogonal to the longitudinal direction.

- The first channel is formed by a first recess in the mixing device.

- The mixing device comprises a first surface arranged opposite the first plate, the first recess opening at the first surface.

- The third channel is formed by a third recess in the mixing device.

- The mixing device comprises a second surface arranged opposite the second plate, the third recess opening at the second surface.

the first channel is in fluid communication with the second channel via at least one first orifice arranged between the first channel and the second channel.

- The third channel is in fluid communication with the second channel via at least one second orifice arranged between the second longitudinal channel and the second channel.

- The mixing device comprises several first and / or third successive channels in the lateral direction.

- The mixing device comprises several second channels succeeding each other in the longitudinal direction.

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 term natural gas refers to any composition containing hydrocarbons including at least methane. This includes a "crude" 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 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 only by way of nonlimiting example and made with reference to the attached diagrams, among which:

FIG. 1 is a schematic sectional view, in a plane parallel to the longitudinal and lateral directions, of part of a passage of the heat exchanger supplied with a two-phase liquid-gas mixture in accordance with one embodiment of the invention;

Figure 2 is a schematic sectional view, in a plane parallel to the longitudinal direction and perpendicular to the lateral direction, of series of passages of the exchanger of Figure 1;

Figure 3 is a schematic sectional view, along a plane perpendicular to that of Figure 1, illustrating an embodiment of a mixing device fitted to an exchanger according to the invention;

Figures 4A, 4B, 5A and 5B are schematic sectional views of mixing devices according to other embodiments of the invention.

Figures 1 and 2 illustrate a heat exchanger 1 according to an embodiment of the invention comprising a stack of plates 2a, 2b, 2c ... which extend in two dimensions, in a longitudinal direction z and a lateral direction y. The plates 2a, 2b, 2c ... are arranged parallel to one another with spacing and thus form a plurality of passages for fluids in relation to indirect heat exchange via said plates. The lateral direction is shown there orthogonal to the longitudinal direction z and parallel to the plates 2a, 2b, 2c ....

Preferably, each passage has a parallelepipedal and flat shape. The gap between two successive plates is small compared to the length and width of each successive plate.

Exchanger 1 may include 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 one refrigerant F1, and a second series of passages 20 (not visible in Figure 1) for channeling at least one circulating fluid F2, l flow of said fluids taking place generally in the longitudinal direction z. The passages 10 of the first series may 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 43, 52 configured to distribute the various fluids selectively in the passages 10, 20, as well as for evacuating 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 located in the 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 opposite corners. The openings placed one above the other are united respectively in collectors of semi-tubular shape 40, 45, 50, 55, through which the distribution and evacuation of the fluids take place.

In the representations of FIGS. 1 and 2, the semitubular collectors 50, 45 are used for the introduction of the fluids into the exchanger 1 and the semi-tubular collectors 40, 55 are used for evacuating these fluids from the exchanger 1 .

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

According to another alternative embodiment, the refrigerant and circulating fluid can also circulate 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 longitudinal direction is oriented vertically when the exchanger 1 is in operation. The refrigerant F1 flows generally vertically and in the upward direction. Other directions and directions of flow of the fluids F1, F2 are of course conceivable, without departing from the scope of the present invention.

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

The distribution and evacuation means 43, 52 advantageously comprise distribution waves 44, 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 44, 51, 54 ensure uniform distribution and 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. Indeed, the heat exchange structures are in contact with the fluids circulating in the passages and transfer thermal fluxes 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 use of fluids under pressure. They also guide the flow of fluid in the passages of the exchanger.

Preferably, these structures include 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 44, 51, 54 along the length. passages 10, 20. The passages 10, 20 of the exchanger thus have a main part of their length constituting the heat exchange part proper, which is provided with a heat exchange structure, said main part being bordered by distribution parts filled with distribution waves 44, 51,54.

Figure 1 illustrates a passage 10 of the first series 1 configured to dispense a refrigerant F1 in the form of a two-phase liquid-gas mixture. The refrigerant F1 is separated in a separator device 6 into a gas phase 61 and a liquid phase 62 introduced separately into the exchanger 1 via a lateral collector 30 and the collector 50. The two phases 61, 62 are then mixed with each other by means of a mixing device 3 arranged in passage 10 and shown schematically in Figure 1. Advantageously, several passages 10, or even all of the passages 10 of the first series have a mixing device 3.

Figure 2 is a schematic sectional view, in a plane parallel to the longitudinal direction z and perpendicular to the lateral direction y, of the exchanger of Figure 1. There is seen a stack of passages 10, 20 of the first and second series, mixing devices 3 being arranged in two passages 10.

The mixing device 3 according to the invention advantageously consists of a bar, or rod, housed in a passage 10 and which 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 2a, 2b forming the passage 10.

The mixing device 3 is advantageously fixed to the adjacent plates 2a and 2b by brazing.

The mixing device 3 is advantageously of generally parallelepiped shape.

The mixing device 3 can have, parallel to the longitudinal direction z, a first dimension comprised between 20 and 200 mm and, parallel to the lateral direction y, a second dimension comprised between 100 and 1400 mm.

As seen in FIG. 3, the mixing device 3 comprises a first surface 3a arranged opposite a first plate 2a of the exchanger and a second surface 3b arranged opposite the second plate 2b. The first and second surfaces 3a, 3b preferably extend parallel to the plates 2a and 2b respectively. The mixing device 3 is preferably arranged in the passage 10 so that the first and second surfaces 3a, 3b are in contact with each plate 2a, 2b.

The mixing device 3 comprises at least a first channel 31 for channeling a gas phase 61 of the refrigerant F1, the direction of flow of the fluid being symbolized by the arrow 61, and at least a second channel 32 for channeling a liquid phase 62 of the refrigerant F1. Said first channel 31 and second channel 32 extend parallel to the first and second plates 2a, 2b.

According to the invention, the mixing device 3 further comprises at least a third channel 37 for channeling the gas phase 61 of the refrigerant F1, said third channel 37 being arranged between the second channel 32 and the second plate 2b and extending in parallel to the first and second plates 2a, 2b.

The arrangement of such a third longitudinal channel 37 makes it possible to create, by the flow of a gas phase in said third channel, a gas barrier acting as a thermal insulator between the second channel and the second plate 2b. This minimizes the indirect heat exchanges that can take place, via the second plate 2b, between the liquid phase 62 circulating in the second channel 32 and the circulating fluid F2 circulating in the adjacent passage 20, which makes it possible to limit, or even to avoid, vaporization of the liquid phase 62 before mixing with the gas phase 61 of the refrigerant F1. The two phases of the mixture are thus distributed as homogeneously as possible within the passages for the two-phase mixture, as well as between the various passages for the two-phase mixture.

This solution has the advantages of being simple to implement, of not modifying the size of the exchanger and of not making its structure more complex.

According to one embodiment of the invention, the first channel31 is arranged between the second channel32 and the first plate 2a.

Preferably, the first and third channels 31, 37 extend in the same longitudinal direction z. Said first and third channels 31, 37 can thus be easily supplied by the gas phase 61 introduced on the same side of the exchanger 1 by a collector 50.

The first and third channels 31, 37 are advantageously in the form of recesses or grooves whose length is large compared to the width or the height of said channels. The longitudinal direction then means the direction in which the channel in question extends lengthwise.

According to one embodiment of the invention, the passages 10, 20 extend in the longitudinal direction z, the first and third longitudinal channels 31, 37 extending in said longitudinal direction z. The second channel 32 extends in the lateral direction y orthogonal to the longitudinal direction z.

In the context of the invention, at least one passage 10 of the first series is defined between a first plate 2a and a second plate 2b, the first plate 2a also defining an adjacent passage 20 of the second series immediately adjacent to the passage 10 considered . A mixing device 3 is arranged in the passage 10 of the first series considered.

The device 3 can be delimited in particular by a first surface 3a arranged opposite the first plate 2a and a second surface 3b arranged opposite the second plate 2b. It can also be delimited by end faces 35, 36 which extend transversely in the passage

10.

The first and / or third channels 31, 37 can be formed by internal recesses formed within the mixing device 3. They can also be through at the level of the surfaces 3a and / or 3b, as illustrated in the Figures.

The channels 31, 37 can open out at the end faces 35, 36 of the mixing device 3, or set back towards the inside of the device 3 with respect to said faces 35, 36.

Preferably, the second channel 32 is formed by an internal non-opening recess formed within the mixing device 3.

Advantageously, the first channel 31 and the second channel 32 are fluidly connected. Preferably, this fluid connection is obtained by at least a first orifice 34 arranged between the first channel 31 and the second channel 32. The first orifice 34 comprises an inlet 342 opening into the second channel 32 and an outlet 341 opening into the first channel 31. One or more first orifices 34 may be disposed along the direction y. Embodiments of such first orifices 34 are illustrated in Figures 3 to 5B.

In operation, the mixing of the liquid 62 and gaseous phase 61 is carried out globally downstream of the outlet 341 and the two-phase liquid / gas mixture is distributed outside the mixing device by one or more passages 33.

Figures 3 to 5B illustrate mixer devices 3 comprising a single second channel 32. The device 3 may also include several second channels 32 succeeding each other within the device 3, in particular along the longitudinal direction z.

Likewise, the mixing device 3 can comprise one or more first and second longitudinal channels 31, 37. FIGS. 4B and 5B illustrate a device 3 comprising a row of first channels 31 and a row of third channels 37 succeeding each other along the lateral direction y. Preferably, the channels 31, 37 extend parallel to each other.

It being specified that the first channel 31 and the second longitudinal channel can be of distinct and identical shape and number.

In an embodiment illustrated in Figures 4A and 4B, the first and third channels 31, 37 are arranged opposite each other of the second channel 32.

In the variant embodiment illustrated in FIGS. 5A and 5B, the first and third channels 31, 37 are arranged in offset on either side of the second channel32.

The distances between the first successive channels 31 and the distances between the third successive channels 37 can also vary.

Preferably, the third channel 37 and the second channel 32 are fluidly connected. As shown in FIGS. 4A, 4B, 5B, the third channel 37 can be in fluid communication with the second channel 32 via one or more second orifices 38 arranged between the third channel 37 and the second channel 32. In this embodiment, the mixing device 3 comprises at least two passages 33 for a two-phase liquid / gas mixture.

FIG. 3 illustrates an embodiment in which the third channel 37 is fluidly isolated from the second channel 32.

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 the skilled person 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 longitudinal direction z, the first channel 31 extending in the longitudinal direction z and the second channel 32 s' extending in a lateral direction y orthogonal to the longitudinal direction z. The reverse is also possible, that is to say a first channel 31 extending in the lateral direction y and a second channel 32 extending in the longitudinal direction z. The lateral y and longitudinal z directions may also not be orthogonal to each other.

Claims (11)

1. Heat exchanger (1) comprising several plates (2a, 2b, 2c, ...) arranged parallel to each other so as to define a first series of passages (10) for channeling at least one refrigerant (F1) and one second series of passages (20) for channeling at least one circulating fluid (F2) to be put in heat exchange relationship with at least said refrigerant (F1), at least one passage (10) of the first series being defined between a second plate (2b) defining an adjacent passage (20) of the second series and a first plate (2a), a mixing device (3) being further arranged in said at least one passage (10) of the first series and comprising: - at least a first channel (31) for channeling a gas phase (61) of the refrigerant (F1), - at least a second channel (32) for channeling a liquid phase (62) of the refrigerant (F1), said first channel (31) and second channel (32) extending parallel to the first and second plates (2a, 2b) , characterized in that the mixing device (3) further comprises at least a third channel (37) for channeling the gas phase (61) of the refrigerant F1, said third channel (37) extending parallel to said second plate ( 2b) and being arranged between the second channel (32) and the second plate (2b). 2. Exchanger according to claim 1, characterized in that the first channel (31) is arranged between the second channel (32) and the first plate (2a). 3. Exchanger according to one of claims 1 or 2, characterized in that the first and third channels (31, 37) extend in the same longitudinal direction (z). 4. Exchanger according to one of the preceding claims, characterized in that the second channel (32) extending in a lateral direction (y) orthogonal to the longitudinal direction (z). 5. Exchanger according to one of the preceding claims, characterized in that the first channel (31) is formed by a first recess (31) formed within the mixing device (3). 6. Exchanger according to claim 5, characterized in that the mixing device (3) comprises a first surface (3a) arranged opposite the first plate (2a), the first recess (31) opening out at the level of the first surface ( 3a). 7. Exchanger according to one of the preceding claims, characterized in that the third channel (37) is formed by a third recess (37) formed within the mixing device (3). 8. Exchanger according to claim 7, characterized in that the mixing device (3) comprises a second surface (3b) arranged opposite the second plate (2b), the third recess (37) opening out at the second surface ( 3b). 9. Exchanger according to one of the preceding claims, characterized in that the first channel (31) is in fluid communication with the second channel (32) via at least one first orifice (34) arranged between the first channel (31) and the second channel (32). 10. Exchanger according to one of the preceding claims, characterized in that the third channel (37) is in fluid communication with the second channel (32) via at least one second orifice (38) arranged between the second longitudinal channel (37) and the second channel (32). 11. Exchanger according to one of the preceding claims, characterized in that the mixing device (3) comprises several first and / or third channels (31, 37) succeeding each other in the lateral direction (y) 1/5