Heat exchanger having an arrangement configuration of a mixing device for improving the metering distribution of a two-phase mixture

Abstract

The present invention relates to a heat exchanger (1) comprising a plurality of plates (2) arranged parallel to one another and in a longitudinal direction (z), the plates (2) being stacked in a spaced relation to one another to define between them at least one first set of flow paths (10A, 10B) configured for the flow of a first fluid (F1) generally in the longitudinal direction (z), and at least one second set of flow paths (20) configured for the flow of a second fluid (F2) in heat exchange relationship with the first fluid (F1), wherein at least one first flow path (10A) of the first set includes a first mixer (3A), and at least one second flow path (10B) of the first set includes a second mixer (3B), each of the first and second mixers (3A, 3B) configured for the flow of a first phase (61) of the first fluid (F1) from at least one first inlet (311A, 311B). a series of longitudinal channels (32A, 32B) extending in a longitudinal direction (z) and configured for the flow of a second phase (62) of a first fluid (F1) from a second inlet (321A, 321B) to a second outlet (322A, 322B), respectively, said longitudinal channels adjoining one another in a transverse direction (y) perpendicular to the longitudinal direction (z); and at least one orifice (34) fluidly connects the at least one transverse channel (31A, 31B) to at least one longitudinal channel (32A, 32B) such that the first and second mixers (3A, 3B) are configured to dispense a mixture of a first phase (61) and a second phase (62) through second outlets (322A, 322B). According to the invention, the longitudinal channels (32A) of the first mixer (3A) are arranged at multiple positions in the transverse direction (y), at least some of which are different from the positions of the longitudinal channels (32B) of the second mixer (3B).

Description

Technical Field

[0001] The present invention relates to a heat exchanger including a plurality of sets of passages, i.e., flow paths, for each of a plurality of fluids involved in a heat exchange relationship, the exchanger including an arrangement of mixing devices configured to more homogeneously distribute at least one mixture of a liquid phase - gas phase two - phase in at least one of the plurality of sets of flow paths.

Background Art

[0002] In particular, the present invention can be applied to a heat exchanger for vaporizing at least one flow of a gas - liquid mixture, in particular a gas - liquid mixture containing a plurality of components, for example a mixture containing hydrocarbons, by exchanging heat with at least one other fluid, for example natural gas to be cooled, or even natural gas to be at least partially liquefied, or even liquefied natural gas to be supercooled.

[0003] Among the methods using one or more fluid cooling cycles using a refrigerant in a two - phase, i.e., liquid / gas mixture state, in particular, several methods for liquefying a natural gas stream to obtain liquefied natural gas (LNG) are known. Generally, a cooling stream, which is a mixture containing a plurality of components, for example a mixture containing hydrocarbons, is generally compressed by a compressor and then introduced into a certain exchanger or a series of exchangers where it is completely liquefied and supercooled to the minimum temperature of the method, which is generally the minimum temperature of the liquefied natural gas stream. At the outlet of the exchanger at the minimum temperature, the cooling stream expands by forming a liquid phase and a gas phase. These two phases are separated by a phase separator and then re - introduced into the exchanger in a gas - liquid mixed state, i.e., a two - phase state, and remixed before being re - introduced into the exchanger. The cooling stream introduced into the exchanger in a two - phase state is vaporized there in contact with the hydrocarbon stream to be liquefied and in contact with natural gas. Pamphlet International Publication No. WO 2017 / 081374 describes one of these known methods.

[0004] By using brazing plates and finned aluminum heat exchangers, it is possible to provide a very compact device with a large exchange surface, thereby enhancing the energy performance of the method and doing so with a finite volume.

[0005] These heat exchangers include a stack of plates, i.e., a plate stack, extending in two dimensions, length and width, thus forming a stack of multiple sets of flow channels, i.e., a stack, positioned overlapping each other, some of which are intended to circulate a heat transfer fluid, e.g., a hydrocarbon stream to be liquefied, and others are intended to circulate a refrigerant, e.g., a two-phase cooling stream to be vaporized.

[0006] Heat exchange structures, e.g., corrugated structures for heat exchange, are generally arranged in the flow channels of the heat exchanger. These structures include fins extending between the plates of the heat exchanger and can increase the heat exchange surface of the heat exchanger. These fins also serve as spacers and contribute to the mechanical strength of the flow channels.

[0007] In heat exchangers with a two-phase cooling stream, several problems occur, especially when these streams vaporize in an upward vertical flow.

[0008] In fact, to ensure the correct operation of the heat exchanger, i.e., especially for heat exchangers that perform a gas-liquid mixture, and especially to maximize the use of its exchange surface, the ratio of the liquid phase to the gas phase needs to be the same in all flow channels and uniform within the same flow channel.

[0009] The sizing of the heat exchanger is calculated by assuming a single temperature at the end of the vaporization of the liquid phase for each flow channel, which is equal to the dew point of the mixture, so as to ensure a uniform distribution of the phases.

[0010] Especially in mixtures containing multiple components, the end of the vaporization temperature depends on the ratio of the liquid phase and the gas phase in the flow channel, because the two phases do not have the same composition.

[0011] If the two phases have a non-uniform distribution, then, accordingly, the temperature profile of the first fluid can vary depending on those flow paths and / or within the same flow path. Due to this non-uniform distribution, one or more fluids in exchange relationship with the two-phase mixture can have an exchanger outlet temperature that exceeds the expected temperature, and thus reduce the performance of the heat exchanger.

[0012] One solution to distribute the liquid and gas phases of the mixture as uniformly as possible involves introducing them separately into the exchanger and then mixing them only once while they are within the exchanger.

[0013] Document FR-A-2563620 or International Publication No. WO 2018 / 172644A describes an exchanger in which grooved bars are inserted into a set of flow paths for flowing a two-phase mixture through channels. This mixing device includes a series of separate channels or grooves for the flow of the liquid phase of the refrigerant and another series of separate channels for the flow of the gas phase of the refrigerant. Since one series of channels is fluidly connected to the other series of channels via openings, the gas-liquid mixture is discharged and distributed towards the heat exchange region from the mixing device. Each refrigerant flow path of the exchanger is provided with such a device.

[0014] One problem that occurs with this type of mixing device relates to the non-uniform distribution of the gas-liquid mixture in the width portion of the exchanger flow path.

[0015] In fact, the two-phase mixture is distributed at the outlets of the channels exiting the flow path. Since the channels are arranged at a certain distance from each other, the gas-liquid mixture is introduced separately into the exchange zone across the width portion of the flow path. Since the fluid flows from one end to the other in the direction of flow within the exchanger, particularly in the case of the corrugated structures for exchange commonly used in this type of exchanger, for example, perforated or "sawtooth" corrugated structures that tend to deflect some of the fluid from its direction of flow, the distribution can occur in a direction perpendicular to the overall direction of flow.

[0016] However, the homogenization of the fluid distribution across the width portion of the exchanger is achieved only after the mixture has traveled a certain distance after exiting the mixing device. Over this travel distance, the fluid supplies the exchange zone with an unequal mass flow rate depending on the position considered within the width portion of the exchanger. Some channels of the corrugated structure for exchange may have limited supply or even no supply. The performance of the exchanger is degraded. In some forms, acceptable homogenization may not be achieved. This is especially the case when the exchange zone has a linear corrugated structure that makes it impossible to distribute the fluid laterally thereby.

[0017] Conditioned on a small temperature deviation between the heat transfer fluid and the refrigerant fluid, the operating exchanger is more sensitive to this insufficient distribution phenomenon. Furthermore, the phenomenon of non-uniform distribution is accelerated in the case of a refrigerant mixture containing multiple components.

[0018] None of the existing solutions are fully satisfactory. Therefore, placing free space at the outlet of the mixing device causes problems in terms of the mechanical strength of the exchanger and may cause the first phase to accumulate in this zone. Increasing the number of channels following each other in the width portion of the exchanger reduces the flow rate in each channel and harms the proper distribution of the mixture at the outlet. Finally, a "hardway" type corrugated structure arrangement at the outlet of the mixing device, or an arrangement of a mixing device with a more complex geometry, increases the pressure loss and thereby degrades the performance of the method. Summary of the Invention Problems to be Solved by the Invention

[0019] An object of the present invention is to address all or some of the above problems, in particular by proposing a mixing device that provides a more homogeneous distribution of the two-phase mixture in the width portion of the exchanger. Means for Solving the Problems

[0020] Therefore, the solution according to the invention comprises a heat exchanger including a plurality of plates arranged parallel to each other and in the longitudinal direction, said plates being spaced apart and stacked, i.e., tiered, to define together at least one first set of flow channels configured such that a first fluid flows generally in the longitudinal direction, and at least one second set of flow channels configured to provide a heat exchange relationship between the flow of a second fluid and the first fluid, at least one first flow channel of the first set including a first mixing device, and at least one second flow channel of the first set including a second mixing device, each of the first and second mixing devices comprising: - at least one lateral channel configured such that a first phase of the first fluid flows from at least one first inlet; - a series of longitudinal channels each extending in the longitudinal direction and configured such that a second phase of the first fluid flows from a second inlet to a second outlet, the series of longitudinal channels being contiguous with each other in a lateral direction perpendicular to the longitudinal direction; and - at least one opening fluidly connecting the at least one lateral channel to at least one longitudinal channel, the first and second mixing devices being configured to distribute a mixture of the first phase and the second phase via the second outlet of their respective longitudinal channels; including, characterized in that the longitudinal channels of the first mixing device are arranged at a plurality of lateral positions at least partially different from the positions of the longitudinal channels of the second mixing device.

[0021] Where applicable, the invention has the following features: - The second mixing device includes two longitudinal edges extending parallel in the longitudinal direction, and each longitudinal channel of the first mixing device is provided laterally between two consecutive longitudinal channels of the second mixing device or between a longitudinal channel and a longitudinal edge of the second mixing device; - The single longitudinal channel of the first mixing device is provided transversely between two consecutive longitudinal channels of the second mixing device or between a longitudinal channel and a longitudinal edge of the second mixing device; - The longitudinal channels of the first mixing device are separated from each other by a first constant distance, and the longitudinal channels of the second mixing device are separated from each other by a second constant distance, preferably the first distance and the second distance are equal; - The series of longitudinal channels of the second mixing device is offset with respect to the series of longitudinal channels of the first device by an offset distance measured transversely, preferably the offset distance is 25 - 75% of the first distance, preferably the offset distance is 50% of the first distance; - The first distance and / or the second distance ranges from 10 to 40 mm, preferably 20 mm or more and 30 mm or less; - Each of the first and second flow paths has a longitudinal symmetry axis extending parallel to the longitudinal direction, and the longitudinal channels of each of the first and second mixing devices are symmetrically arranged with respect to the longitudinal symmetry axis; - The transverse position of the longitudinal channels of the second mixing device coincides with the transverse position of the longitudinal channels of the first device after a 180° rotation in the plane defined by the transverse and longitudinal directions; - Including a plurality of alternately arranged first flow paths and second flow paths, at least one flow path of the second set is arranged between at least one first flow path and at least one second flow path following the at least one first flow path; - The transverse channels and / or longitudinal channels of the first mixing device and the second mixing device are straight, preferably in the shape of a parallelepiped or substantially parallelepiped; - The first and second mixing devices each include a series of transverse channels extending transversely and following each other longitudinally and may include one or more of the above.

[0022] According to another aspect, the present invention relates to a method for liquefying a stream containing hydrocarbons such as natural gas as a second fluid, the method implementing at least one exchanger according to the present invention and: a) introducing the hydrocarbon stream into a second set of flow paths; b) introducing a cooling stream into a third set of flow paths of the heat exchanger; c) discharging the cooling stream from the heat exchanger and expanding the cooling stream to at least one pressure level to produce at least one two-phase cooling stream; d) separating at least a portion of the two-phase cooling stream resulting from step c) into a gas phase and a liquid phase; e) introducing at least a portion of the gas phase and at least a portion of the liquid phase into the first and second flow paths of the first set, respectively, via separate inlets of the first and second flow paths; f) passing the phases introduced in e) through the first and second mixing devices so as to obtain, at the respective outlets of the first and second mixing devices, a first fluid formed by a mixture of a first phase (61) and a second phase; g) vaporizing at least a portion of the first fluid resulting from step f) by exchanging heat with at least the hydrocarbon stream in the first and second flow paths so as to obtain, at the outlet of the exchanger, a cooled and / or at least partially liquefied hydrocarbon stream including.

[0023] The expression "natural gas" refers to any hydrocarbon-containing composition containing at least methane. This is a "raw" composition (before any treatment or scrubbing), and also any composition that has been partially, substantially or entirely treated to reduce and / or eliminate one or more compounds, such as, but not limited to, sulfur, carbon dioxide, water, mercury, and certain heavy and aromatic hydrocarbons.

[0024] The present invention will now be better understood, merely by way of non-limiting example, with reference to the accompanying drawings and the following description.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Best Mode for Carrying Out the Invention

[0026] FIG. 1 is a cross-sectional view of a heat exchanger 1 including a stack (not shown) of plates 2 extending 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, vertically, with a space therebetween, thus forming a stack of flow paths for fluids in an indirect heat exchange relationship via the plates.

[0027] Preferably, each flow path has a flat parallelepiped shape. The gap between two consecutive plates is small compared to the length measured in the longitudinal direction z and the width measured in the transverse direction y of each flow path.

[0028] The exchanger 1 may include more than 20, or even more than 100 plates, together defining a first set of first and second flow paths 10A, 10B (flow path 10B not shown in FIG. 1) for flowing at least one first fluid F1 through channels, and a second set of flow paths 20 (not shown in FIG. 1) for flowing at least one second fluid F2 through channels, the flow of said fluids generally occurring in the direction z. The flow paths 10A, 10B may be arranged alternately and / or adjacent to all or some of the flow paths 20, either wholly or partly. The exchanger 1 may include a third set of flow paths, or more sets of flow paths, for the flow of one or more additional fluids. These multiple sets of flow paths are stacked on top of each other to form a stack of flow paths.

[0029] Seals for the flow paths 10A, 10B, 20 along the edges of the plate 2 are generally provided by laterally and longitudinally sealing strip pieces 4 attached to the plate 2. The laterally sealing strip pieces 4 do not completely seal the flow paths 10A, 10B, 20, and advantageously leave fluid inlet and outlet openings located at opposite corners, i.e., diagonally across the flow paths.

[0030] The openings of the first set of flow paths 10A, 10B are arranged to be vertically aligned, while the openings of the second set of flow paths 20 are arranged at opposite corners. The vertically arranged openings are joined by semi-tubular manifolds 40, 45, 52, 55 respectively, through which the fluid is distributed into and discharged from the flow paths 10A, 10B, 20.

[0031] It should be noted that forms for introducing and discharging fluids other than those shown in FIG. 1 may be used. Therefore, the openings of the flow paths can be arranged at other positions in the width portion of the exchanger, particularly at the center of the width portion of the exchanger, and / or at other positions in the length portion of the exchanger. In the description of FIG. 1, the semi-tubular manifolds 52 and 45 are used to introduce fluid into the exchanger 1, and the semi-tubular manifolds 40, 55 are used to discharge these fluids from the exchanger 1.

[0032] In this alternative embodiment, the manifold for supplying one of the fluids and the manifold for discharging the other fluid are located at the same end of the exchanger. Therefore, the fluids F1, F2 flow through the exchanger 1 in a countercurrent manner.

[0033] According to another alternative embodiment, the first and second fluids can also circulate in a cocurrent manner. Therefore, the means for supplying one of the fluids and the means for discharging the other fluid are located at opposite ends of the exchanger 1.

[0034] Preferably, the direction z is in a vertical orientation when the exchanger 1 is operating. The first fluid F1 generally flows vertically and upward. Other flow directions and courses of the fluids F1, F2 can clearly be considered without departing from the scope of the present invention.

[0035] It should be noted that within the scope of the present invention, one or more second fluids F2 having different properties can flow through the second set of flow paths 20.

[0036] Preferably, the first fluid F1 is a refrigerant and the second fluid F2 is a heat transfer fluid.

[0037] The exchanger advantageously includes distribution corrugated structures 51, 54 in the form of corrugated sheets arranged between two consecutive plates 2 and extending from the inlet opening and the outlet opening. The distribution corrugated structures 51, 54 ensure a uniform distribution and recovery of the fluid across the entire width of the flow paths 10A, 10B, 20.

[0038] Furthermore, the flow paths 10A, 10B, and 20 advantageously include a heat exchange structure disposed between the two plates. The purpose of these structures is to increase the exchange coefficient between the fluids by increasing the heat exchange surface area of the exchanger and making the flow more turbulent. In fact, the heat exchange structure is in contact with the fluid circulating in the flow path and transfers the heat flow by conduction to the adjacent plate 2 that can be attached by brazing, thereby increasing the mechanical strength of the exchanger.

[0039] The heat exchange structure also serves as a spacer between the plates 2, especially when assembling the exchanger by brazing and to avoid any deformation of the plates when flowing a pressurized fluid. The heat exchange structure also ensures that the fluid flow is properly guided within the flow paths of the exchanger.

[0040] Preferably, these structures include a corrugated structure 11 for heat exchange, which advantageously is an extension of the corrugated structure for distribution along the length portion of the flow path and extends across the entire width portion and length portion of the flow paths 10A, 10B, 20 parallel to the plate 2. Therefore, the flow paths 10A, 10B, 20 of the exchanger have a major portion of those length portions that form the heat exchange portion itself where the heat exchange structure is made, and the major portion is bounded by the distribution portions where the distribution corrugated structures 51, 54 are made.

[0041] FIG. 1 shows a first set of first flow paths 10A configured for the flow of a first fluid F1 in the form of a two-phase mixture, also called a two-phase mixture. The first set includes a plurality of first flow paths 10A of this type, as well as a plurality of second flow paths 10B stacked on the first flow paths and having a structure similar to that of the first flow paths 10A. The first fluid F1 is separated in the separation device 6 into a first phase 61 and a second phase 62 and is introduced separately into the exchanger 1 by a separate first manifold 30 and a second manifold 52. Preferably, the first phase 61 is a liquid phase and the second phase 62 is a gas phase.

[0042] Therefore, the first and second phases 61, 62 are mixed by a first mixing device 3A disposed in at least one first flow path 10A. Advantageously, some of the first set of first flow paths 10A, or even all of the flow paths 10A, include the first mixing device 3A. Similarly, the first and second phases 61, 62 are mixed by a second mixing device 3B disposed in at least one second flow path 10B. Advantageously, some of the first set of second flow paths 10B, or even all of the flow paths 10B, include the second mixing device 3B. Semi-tubular manifolds 52 and 55 are fluidly connected to the inlets and outlets of the flow paths 10A and 10B. The first manifold 30 is fluidly connected to at least one first inlet 311A, 311B of each of the first and second mixing devices 3A, 3B. The second manifold 52 is fluidly connected to at least one second inlet 321A, 321B of each of the first and second mixing devices 3A, 3B.

[0043] It should be noted that FIG. 1 shows a mixing device 3A positioned at a certain distance from the distribution zone 51 of the exchanger 1. According to an alternative embodiment, the first mixing device 3A can be positioned immediately after the distribution zone or can be made in one piece with the distribution zone so as to be in parallel with said zone. According to this latter possibility, the mixing device forms a one-piece part, which can be manufactured by conventional machining or by additive manufacturing, i.e., three-dimensional printing, for example, by laser sintering.

[0044] FIG. 2 is, advantageously, a three-dimensional view of a first mixing device 3A composed of bars or rods housed in the first flow path 10A. The second mixing device 3B can have all or some of the features described with respect to the first device 3A.

[0045] The first mixing device 3A preferably extends into the section of the flow path 10 over most or even all of the height portion of the first flow path 10A, so that the mixing device is in contact with each plate 2 forming the first flow path 10A.

[0046] The first mixing device 3A is advantageously attached to the plate 2 by brazing.

[0047] The first mixing device 3A advantageously has an overall parallelepiped shape.

[0048] Preferably, the first mixing device 3A is a one-piece part, i.e., formed by a block or as a single piece. The first mixing device 3A can be manufactured by conventional machining or by additive manufacturing. The first mixing device 3A can have a first dimension ranging from 20 to 200 mm parallel to the longitudinal direction z and a second dimension ranging from 100 to 1,400 mm parallel to the transverse direction y.

[0049] The first mixing device 3A includes at least one transverse channel 31A configured such that the first phase 61 of the first fluid F1 flows in from at least one first inlet 311A. Preferably, the transverse channel 31A extends parallel to the transverse direction y.

[0050] Furthermore, it includes a series of longitudinal channels 32A extending parallel to the longitudinal direction z and configured such that the second phase 62 of the first fluid F1 flows from the second inlet 321A to the second outlet 322A, and the longitudinal channels 32 are located at positions y i , y i+1 ,.. that are continuous in the transverse direction y.

[0051] Preferably, the transverse channel 31A extends over the entire second dimension and / or the longitudinal channel 32A extends over the entire first dimension.

[0052] Preferably, the mixing device 3A includes at least one first inlet 311A in fluid communication with the first manifold 30 and a second inlet 321A that is remote from, i.e., separate from, the first inlet 311 and in fluid communication with the second manifold 52. The first manifold 30 is fluidly connected to the first phase source 61, and the second manifold 52 is fluidly connected to a separate second phase source 62. The at least one first inlet 311A and the at least one second inlet 321A are brought into fluid communication via at least one opening 34. The first and second inlets are advantageously formed by causing lateral and longitudinal channels to emerge from the lateral and longitudinal peripheral edges of the devices 3A, 3B.

[0053] Figure 2 shows the introduction of the first phase 61 via an end of the device 3A that includes a plurality of first inlets 311A. According to an advantageous embodiment, the first mixing device 3A includes at least one other first inlet for the first phase 61 provided at the opposite end of the device 3A. Advantageously, these other inlets are obtained by extending the lateral channels 31A, 31B until they emerge from the opposite lateral edges of the exchanger 1. In this case, a separate first manifold 30 is arranged on the opposite side of the exchanger 1. The introduction of the first phase 61 on both sides of the mixing device can reduce the influence of the pressure loss when the first phase flows through the lateral channels, thereby promoting a more homogeneous distribution of the two-phase mixture across the width portion of the exchanger.

[0054] Preferably, the first mixing device 3A includes a mixing volume portion located within the longitudinal channel 32A downstream of the opening 34 in the direction of flow of the first phase 61 at the opening 34.

[0055] The transverse channel 31A is fluidly connected to at least one longitudinal channel 32A, and when a first phase 61 flows through the transverse channel 31A and a second phase 62 flows through the longitudinal channel 32A, the first mixing device 3A distributes a mixture of the first phase 61 and the second phase 62, preferably a liquid / gas two-phase mixture F1, via the second outlet 322A of the channel 32A. Preferably, the longitudinal channel and / or the transverse channel are generally straight.

[0056] Advantageously, the channels 31A, 32A are in the form of elongated recesses provided in the mixing device 3. The channels preferably emerge from the upper surface 3a and the lower surface 3b of the mixing device 3A.

[0057] Preferably, the channels 31A, 32A have a square or rectangular cross-section, but optionally can take other shapes (round, rounded parts, etc.).

[0058] The opening 34 is advantageously a perforation made in the material of the device 3A and extending between the transverse channel 31A and the longitudinal channel 32A, preferably in a plane formed by the directions x and y. The opening 34 can be inclined with respect to the direction x or, preferably, can be aligned with the vertical direction x. Preferably, the opening 34 has cylindrical symmetry and more preferably is cylindrical.

[0059] Preferably, the at least one transverse channel 31A includes a bottom wall 3c, and the at least one longitudinal channel 32A includes a top wall 3d extending opposite the bottom wall 3c. The opening 34 is drilled in the bottom wall of the transverse channel 31 and emerges from the top wall of the longitudinal channel 32A.

[0060] Figure 3 is a view of the mixing device 3A of Figure 2 in a cross-section perpendicular to the transverse direction y and passing through the opening 34.

[0061] For reasons of economy, mixing devices of the same geometric shape are usually arranged in a first set of flow channels 10A, 10B, in particular in longitudinal channels arranged at the same position, especially in the transverse direction y.

[0062] At the outlet of each longitudinal channel, the flow of the two-phase mixture of the first fluid F1 preferably occurs in the longitudinal direction z, and the flow expands gradually in the width portion of the flow channel. The homogenization of the flow in each flow channel is only obtained beyond a certain distance as the mixture spreads. This lack of homogenization of the mixture F1 occurs throughout the stack of the first set of flow channels 10A, 10B.

[0063] To address these problems, the present invention proposes arranging a first mixing device 3A and a second mixing device 3B in a first flow channel 10A and a second flow channel 10B of a first set respectively, wherein the mixing devices have different forms, and at least a part, preferably all, of the longitudinal channels 32A of the first mixing device 3A are positioned at a different position in the transverse direction y from the longitudinal channels 32B of the first mixing device 3A. It should be noted that the term "at least some" is understood to mean one or more or all of the consecutive longitudinal channels 32A.

[0064] This enables the distribution of the two-phase mixture of fluid F1 at a plurality of points that are differently distributed across the width portion of the exchanger. Therefore, by considering the assembly formed by the first flow path 10A and the second flow path 10B, the homogenization of the two-phase mixture experienced by the second fluid is generally improved. In fact, by considering arranging the outlets of the longitudinal channel 32A and the longitudinal channel 32B in the same plane, the distance measured in the transverse direction y that separates one channel from the next can be shortened. In the prior art, that is, in two mixing devices at the same channel position, the distance that separates one channel from the next is necessarily equal to the channel-to-channel distance of each device. It should be noted that in the present invention, it is possible to achieve better homogenization without the flow of fluid within each longitudinal channel being affected or significantly affected.

[0065] Thanks to the present invention, after a shorter propagation distance of the mixture downstream of the mixing device, the difference in the mixing rate in the width portion of the exchanger is reduced or even eliminated. The heat exchange between the two-phase mixture and the second fluid F2, and thus the operation of the exchanger, is improved.

[0066] Furthermore, the mechanical strength of the exchanger during brazing or during the operation of the exchanger is improved. In fact, the channels 32A and 32B are no longer stacked and positioned within the stack of the exchanger, and as a result, the locations where there is no material within the channels 32A and 32B are better distributed, thereby strengthening the stack. Furthermore, due to the better distribution of the two-phase mixture experienced by the second fluid, the thermal stress is reduced.

[0067] Preferably, the first set of flow paths for the flow of the two-phase mixture includes a plurality of first flow paths 10A and a plurality of second flow paths 10B including the first and second mixing devices configured according to the present invention. The first flow paths 10A and the second flow paths 10B are advantageously positioned alternately within the stack of flow paths forming the exchanger.

[0068] Preferably, at least one flow path 20 of the second set is arranged between at least one first flow path 10A and at least one second flow path 10B following the at least one first flow path 10A. In particular, the stack of flow paths can have the following alternating pattern: first flow path 10A, flow path 20, second flow path 10B, flow path 20, first flow path 10A, flow path 20, etc. Therefore, the number of refrigerant flow paths is minimized. According to another possibility, the stack of flow paths can have the following alternating pattern: first flow path 10A, second flow path 10B, flow path 20, first flow path 10A, second flow path 10B, flow path 20, etc.

[0069] The present invention enables better homogenization of the total amount of the two-phase mixture cooled and supplied to the second heat transfer fluid, and therefore improves the performance of the exchanger.

[0070] Figures 4 and 5 show embodiments of the first and second devices 3A, 3B according to the present invention. The devices 3A, 3B are shown side by side in the same plane, but during operation, the devices are arranged in separate flow paths 10A, 10B that are stacked in the direction x, and it should be noted that the devices are preferably in the same position in the longitudinal direction z. The positioning of the longitudinal channels 32A, 32B within the devices 3A, 3B is schematically indicated by vertical lines. Axis AA represents the longitudinal symmetry axis of each flow path 10A, 10B in the plane formed by the directions y and z.

[0071] Figures 4 and 5 schematically show the longitudinal channels in the form of lines. The position y of each channel in the transverse direction y i , y i+1 , y i+2 ... can be determined by considering the position of the center of each channel in the transverse direction y. For example, with respect to a channel in the form of a parallelepiped or substantially parallelepiped groove as shown in Figure 2, as shown in Figure 2, the position of the channel in the direction y corresponds to the position of the symmetry axis of the channel that is equidistant from the transverse walls of the channel.

[0072] Preferably, the longitudinal channel 32A of the first mixing device 3A is separated from each other by a first constant distance D A and the longitudinal channel 32B of the second mixing device 3B is separated from each other by a second constant distance D B . The distance D A , D B is measured parallel to the longitudinal direction y

[0073] Preferably, the first distance D A and the second distance D B are equal

[0074] The first distance D A and / or the second distance D B can range from 10 to 40 mm, preferably 20 mm or more, and 30 mm or less

[0075] Preferably, the mixing devices 3A, 3B are each defined by two longitudinal edges 3e

[0076] Preferably, the mixing devices 3A, 3B are dimensioned to at least partially cover, preferably entirely cover, the longitudinal sealing strip 4 that seals the flow path in the longitudinal direction z

[0077] Therefore, the mixing devices 3A, 3B have an effective width L that is less than the distance between the two longitudinal edges 3e and corresponds to the width of the mixing device exposed to the fluid, that is, the width of the flow path 10A or 10B y The mixing devices 3A, 3B have an effective width zone L extending between the two ends 81 y and an overlapping zone 80 extending beyond the flow paths 10A, 10B, and the width of the overlapping zone preferably corresponds to the width of the lateral sealing strip 4 as shown in FIG. 1. Such an arrangement ensures the rigidity of the stack and better mechanical strength of the brazed assembly

[0078] Preferably, each longitudinal channel 32A of the first mixing device 3A is provided in the transverse direction y between two consecutive longitudinal channels 32B of the second mixing device 3B, or between one longitudinal channel 32B of the second mixing device 3B and the longitudinal edge 3e.

[0079] Preferably, a single longitudinal channel 32A of the first mixing device 3A is provided in the transverse direction y between two consecutive longitudinal channels 32B of the second mixing device 3B, or between one longitudinal channel 32B of the second mixing device 3B and the transverse edge 3e.

[0080] Preferably, each pair of consecutive longitudinal channels 32B of the second mixing device 3B corresponds to a longitudinal channel 32A of the first mixing device 3A provided between said pair of channels, and optionally, one longitudinal channel 32A of the first mixing device 3A is provided between one longitudinal channel 32B of the second mixing device 3B and the transverse edge 3e.

[0081] Preferably, a series of longitudinal channels 32B of the second mixing device 3B is offset by a predetermined offset distance D measured in the transverse direction y with respect to a series of longitudinal channels 32A of the first device 3A y only.

[0082] Preferably, the offset distance D y is 25 to 75% of the first distance D A and preferably, the offset distance D y is about 50% of the first distance D A The expression "about" means 50% or approximately 50% with a variation of ± 10% of this value.

[0083] In the form according to FIG. 4, the first and second mixing devices have the same structure, and one of the mixing devices is rotated by 180° with respect to the other in the plane formed by the directions y and z before being attached to its flow path. The advantage of this form is that only one type of mixing device needs to be manufactured, and different distributions of the longitudinal channels 32A, 32B can be obtained by simply rotating the device in the plane formed by the directions y and z. Conveniently, the distance D A and D B are equal, and the offset D y is equal to half of D A . The number of longitudinal channels 32A, 32B of the first and second mixing devices is the same. In one of the mixing devices, the longitudinal channels 32A, 32B are arranged such that the first longitudinal channel in a series is located at a distance D A from one end 81 of the effective zone, and the last longitudinal channel 32A in the series is located at a distance D A / 2 from the opposite end 81 of the effective zone, and vice versa for the other mixing device.

[0084] FIG. 5 shows an alternative embodiment in which the longitudinal channels of the first and second flow paths 10A, 10B are symmetrically arranged with respect to the symmetry axis AA of the exchanger. The advantage of this form is that the distribution points of the two-phase mixture are kept in a symmetric state in the width portion of the exchanger. Conveniently, the distance D A and D B are equal, and the offset D y is equal to half of D A . One of the first and second mixing devices has additional longitudinal channels compared to the other mixing device. In one of the mixing devices, the longitudinal channels 32A, 32B are arranged such that the first and the last longitudinal channels 32A in a series are located at a distance D A from the respective opposite ends 81 of the effective zone. In the other mixing device, the first and the last longitudinal channels in the series are located at a distance D A / 2 from the opposite end 81 of the effective zone. The effective width L of the mixing devicey is a multiple of the distance D A .

[0085] According to a preferred embodiment, since the first and second mixing devices 3A, 3B are arranged in their respective flow paths 10A, 10B, all of their lower surfaces 3b where their longitudinal channels 32A, 32B appear are directed in the vertical direction x, or, as particularly shown in FIG. 3, all are directed in the direction opposite to the vertical direction x.

[0086] According to an alternative embodiment, at least one of the first mixing devices 3A has a lower surface 3b directed in a direction opposite to the direction of the orientation of the lower surface 3b of at least one second mixing device 3B and / or at least one other first mixing device 3A, that is, at least one first mixing device is reversed by 180° around an axis with respect to the direction y before being arranged in its flow path. Thereby, among other things, the flow of the two-phase mixture can be directed towards some adjacent flow paths 20 of the second set in order to promote heat exchange with a certain amount of heat transfer fluid. For example, an alternating orientation of the lower surfaces 3b of the first and second mixing devices in which the flow paths are alternately stacked continuously can be considered.

[0087] The above description is provided by considering two forms of the mixing device, and it is understood that three or more forms can be implemented and one or more of the features that can be applied can be included. In particular, the longitudinal channels of the additional mixing device are arranged at positions different from the positions of the first and second mixing devices in the lateral direction y. In particular, in the case of three different mixing devices, the exchanger includes a third mixing device 3C provided with a longitudinal channel 32C, and the longitudinal channels of the first mixing device 3A and the second mixing device 3B are arranged between two consecutive longitudinal channels 32C of the third device in the lateral direction y, or between the longitudinal channel 32C and the longitudinal edge of the third device 3C.

[0088] To explain the overall homogenization effect obtained by the present invention, FIG. 6 shows the conventional arrangement of the flow paths with the same type of mixing device (Form A), and the arrangement of the flow paths with the first and second mixing devices configured according to the present invention (Form B), including the results of the simulation of the propagation of the two-phase mixture in the exchanger.

[0089] In Form A, each flow path of the first set included a mixing device in the form of a grooved bar, which included, as longitudinal channels, a series of parallelepiped-shaped grooves that were continuous with each other at regular intervals of 30 mm, and, as transverse channels, a series of parallelepiped-shaped grooves that were fluid-connected to the longitudinal channels by a single opening for each longitudinal channel. The geometric shape of the openings was the same for all of the longitudinal channels. The longitudinal channels of each mixing device were the same in number and were arranged at the same position y in the transverse direction y i 、y i+1 ,..

[0090] In Form B, the first and second mixing devices were alternately arranged in the flow paths of the first set of flow paths of the exchanger. The first and second mixing devices were in the form of grooved bars identical to those of Form A. In particular, the grooves were such that a series of grooves forming the longitudinal channels of the second mixing device were offset by a distance D y =D A / 2 from a series of grooves forming the longitudinal channels of the first mixing device, except that they were positioned at a distance D A =D B = 30 mm from each other.

[0091] In Forms A and B, a "sawtooth" type of wavy structure 11, i.e., one that was partially offset, was arranged at the outlet of the mixing device in each flow path. These wavy structures were of the "1 / 8" sawtooth" type (1" = 1 inch = 25.4 mm), i.e., the sawtooth length was 25.4 / 8 = 3.18 mm, and had a wavy structure with a density of 24 fins per inch (1 inch = 25.4 millimeters) measured in the transverse direction y. The hypothesis of the simulation was that the mixing rate was evenly divided into two for each change in the sawtooth of the wavy structure.

[0092] Figure 6 shows, in the longitudinal direction z, the dimensionless mass flow rate obtained in the transverse direction y at a propagation distance of 200 mm after exiting the longitudinal channel, averaged over all of the flow paths of the first set of flow paths of the exchanger. It can be seen that the amplitude of the change in the flow rate in the width portion of the exchanger is reduced in Configuration B according to the present invention.

[0093] Figures 7 and 8 show examples of methods for operating one or more exchangers according to the present invention.

[0094] Figure 7 schematically shows a method for liquefying a hydrocarbon stream 102 that can be a natural gas from which at least one of the following components: water, carbon dioxide, sulfur compounds, methanol, mercury, has been optionally pre-treated before being introduced into the heat exchanger 1.

[0095] Preferably, the hydrocarbon stream contains at least 60%, preferably at least 80% methane as a molar fraction.

[0096] The hydrocarbon stream 102 and the cooling stream 202 enter the exchanger 1 via a third inlet 25 and a fourth inlet 21 respectively, where they circulate in a direction parallel to the longitudinal direction z that is substantially vertical during operation within dedicated flow paths of the exchanger. The hydrocarbon stream 102 circulates through a second set of flow paths 20 supplied by the third inlet 25. The cooling stream 202 circulates through a third set of flow paths arranged within the stack forming the exchanger 1. These streams exit via a third outlet 22 and a first outlet 23. The second and third sets of flow paths are arranged alternately and / or adjacent to all or some of the first set of flow paths 10A, 10B, either wholly or in part.

[0097] Conveniently, the fourth inlet 21 for the cooling stream 202 and the third inlet 25 for the hydrocarbon stream 102 are arranged such that the cooling stream 202 and optionally the hydrocarbon stream 102 flow downstream in parallel towards the second end 1b of the exchanger located at a level lower than the first end 1a of the exchanger. Preferably, the first end 1a corresponds to the hot end of the exchanger 1, i.e., the inlet point of the exchanger where the fluid is introduced at the highest temperature of the exchanger, and this inlet point can be the fourth inlet 21 or the third inlet 25 depending on the method.

[0098] The hydrocarbon stream 102 can be introduced into the exchanger 1 at a temperature ranging from -130 to 40 °C.

[0099] According to one possibility, the hydrocarbon stream 102 is introduced into the exchanger in a completely gaseous or partially liquefied state at a temperature ranging from -80 to -35 °C.

[0100] According to another possibility, the hydrocarbon stream 102 is introduced into the exchanger 1 in a completely liquefied state at a temperature ranging from -130 to -100 °C.

[0101] The cooling stream 201 exiting the exchanger 1 is expanded by an expansion component T3, such as a turbine, valve, or a combination of a turbine and a valve, to form a two-phase cooling stream 203 containing a liquid phase and a gas phase. The two-phase cooling stream 203 forms the first previously considered fluid F1. At least a portion of the two-phase cooling stream 203 resulting from the expansion is introduced into a separation component 27. The separation component can be any device adapted to separate the two-phase fluid into a mainly gas stream on one hand and a mainly liquid stream on the other hand.

[0102] The gas phase 62 is introduced via a manifold 52 that supplies the second inlets 321A, 321B of the first and second mixing devices 3A, 3B disposed in the first and second flow paths 10A, 10B of the first set. The liquid phase 61 is introduced via a first manifold 30 that supplies the first inlets 311A, 311B of the first and second mixing devices 3A, 3B (not shown in FIG. 7).

[0103] Preferably, the gas phase is introduced via an inlet located in the region of the second end 1b corresponding to the low-temperature end of the exchanger 1, i.e., the inlet point of the exchanger where the fluid is introduced at the lowest temperature of the fluid within the exchanger.

[0104] The two phases 61, 62 of the two-phase stream 203 are recombined within the exchanger 1 and are distributed in the gas-liquid mixed state to the first flow path 10A and the second flow path 10B of the exchanger 1, each provided with a first mixing device 3A and a second mixing device 3B according to the present invention.

[0105] Preferably, the two-phase cooling stream 203 is introduced into the heat exchanger 1 at a first temperature T1 ranging from -120 to -160 °C and exits the heat exchanger 1 at a second temperature T2 higher than the first temperature T1 (preferably, T2 ranges from -35 to -130 °C).

[0106] According to another possibility, the two-phase cooling stream 203 is introduced into the heat exchanger 1 at a first temperature T1 ranging from -130 to -80 °C and exits the heat exchanger 1 at a second temperature T2 higher than the first temperature T1 (preferably, T2 ranges from -10 to 50 °C).

[0107] At least a part of the two-phase cooling stream 203 flows upward through the flow paths 10A, 10B and is vaporized by cooling the natural gas 102 and the cooling stream 202 in a countercurrent flow. Therefore, a cooled and / or at least partially liquefied hydrocarbon stream 101 is obtained at the outlet of the exchanger 1.

[0108] The vaporized cooling stream exits the exchanger 1 via a second outlet 42 connected to the manifold 55, is compressed by a compressor, and then cooled in an indirect heat exchanger by exchanging heat with an external cooling fluid, such as water or air (at 26 in Figure 1). The pressure of the cooling stream at the outlet of the compressor can range from 2 MPa to 9 MPa. The temperature of the cooling stream at the outlet of the indirect heat exchanger can range from 10 °C to 45 °C.

[0109] In the method described with reference to Figure 7, the cooling stream is not separated into separate fractions, but in order to optimize the approach within the exchanger 1, the cooling stream can also be separated into two or three fractions, each fraction being expanded at a different pressure level and then sent to different stages of the compressor.

[0110] Preferably, the cooling stream 202 contains hydrocarbons having at most 5 carbon atoms, preferably at most 3 carbon atoms, more preferably at most 2 carbon atoms.

[0111] Preferably, the cooling stream 202 is formed by, for example, a mixture of hydrocarbons and nitrogen, such as a mixture of methane, ethane and nitrogen, but may also contain propane, butane, isobutane, n - butane, pentane, isopentane, n - pentane and / or ethylene.

[0112] The percentage ratio of the molar fractions of the components of the cooling stream can be as follows: - Nitrogen: 0% - 10% - Methane: 20% - 70% - Ethane: 30% - 70% - Ethylene: 20 - 70% - Propane: 0% - 20% - n - Butane: 0% - 30% - Isopentane: 0% - 20%

[0113] Optionally, the cooling stream can contain ethylene instead of ethane, all or some of propane replaced by C4, C5 - type compounds.

[0114] Preferably, the natural gas is at a temperature that is at least 10 °C higher than the bubble temperature of the liquefied natural gas produced at preferably atmospheric pressure (the bubble temperature means the temperature at which the first vapor bubble is formed at a given pressure in the liquid natural gas), and at the same pressure as the inlet pressure of the natural gas and the closest pressure loss, and is at least partially liquefied and exits the exchanger 1 at 101. For example, the natural gas exits the exchanger 1 at a temperature ranging from -100 °C to -162 °C and at a pressure ranging from 2 MPa to 7 MPa. Under these temperature and pressure conditions, and depending on its composition, the natural gas generally does not remain liquid after expanding to atmospheric pressure.

[0115] Advantageously, the method for liquefying a hydrocarbon stream according to the present invention may implement one or more additional cooling cycles that are performed upstream of the main cooling cycle described above to pre-cool the hydrocarbon stream.

[0116] FIG. 8 schematically shows a method for liquefying a hydrocarbon stream, such as natural gas, including an additional cooling cycle, where the natural gas is cooled to a temperature close to its dew point using at least two different expansion levels to increase the efficiency of the cycle. This additional cooling cycle is performed by an additional cooling stream 300 in an additional heat exchanger 2 called a pre-cooling exchanger, and the additional heat exchanger is arranged upstream of the heat exchanger 1 in the flow direction of the hydrocarbon stream 110, thus forming a liquefaction exchanger.

[0117] In this embodiment, the feed stream 110 reaches a pressure ranging from, for example, 2.5 MPa to 7 MPa and a temperature ranging from 20 °C to 60 °C. In the feed stream 110 containing a hydrocarbon such as natural gas, the cooling stream 202 and the additional cooling stream 300 enter the additional exchanger 2 and circulate inside it in a downward direction, in a parallel direction, and in a countercurrent direction.

[0118] The cooled or even at least partially liquefied hydrocarbon stream 102 exits the precooling exchanger 2. Preferably, the hydrocarbon stream 102 exits in a gaseous or partially liquefied state at a temperature ranging, for example, from -35°C to -70°C. The cooling stream 202 also exits the exchanger 2 completely condensed at a temperature ranging, for example, from -35°C to -70°C. Thereafter, the stream 102 is introduced into the exchanger 1.

[0119] As can be seen from FIG. 8, the stream 203 is vaporized in the exchanger 1, exits the exchanger, is compressed by the compressor K2, and then is cooled by exchanging heat with an external cooling fluid, such as water or air, in the indirect heat exchanger C2. Thereafter, the cooling stream resulting from the exchanger C2 is returned to the additional exchanger 2.

[0120] The additional cooling stream 300 can be formed by a hydrocarbon mixture, such as a mixture of ethane and propane, but may also contain methane, ethylene, propylene, butane and / or pentane. The percentage ratio of the molar fraction of the components of the first refrigerant mixture can be as follows: - Ethane: 30% - 70% - Propane: 30% - 70% - Butane: 0% - 20%

[0121] Similarly, in the additional brazing plate and fin type exchanger 2, at least two partial streams resulting from the additional cooling stream 300 are withdrawn from the exchanger at at least two separate outlet points and then expanded at different pressure levels, causing partially two-phase expanded streams each containing a first phase and a second phase. At least a part of these partially two-phase streams is introduced into the respective separation components 24, 25, 26.

[0122] In the embodiment of FIG. 8, a partial flow rate of the additional cooling stream 300 of the first phase, or three fractions also called streams 301, 302, 303, are continuously withdrawn.

[0123] The gas phase and the liquid phase separated by each separation component are introduced via separate inlets of an additional heat exchanger 2 and recombined in a mixing device (not shown) to form at least two refrigerant fluids that are introduced into a dedicated refrigerant flow path in a gas-liquid mixed state. Alternatively, only the liquid phase is injected into the exchanger 2, and the gas phase is directed towards the inlet of the compression stage of the compressor K1. These refrigerants are vaporized in the additional exchanger 2 by exchanging heat with the supply stream 110, the cooling stream 200, and an additional cooling stream 300.

[0124] Advantageously, at least two types of mixing devices 2 are arranged in an additional exchanger, such as those that can be arranged in the exchanger 1 according to the invention. Therefore, the additional exchanger includes at least two refrigerant flow paths each including a mixing device, and these two devices include one or more of the features described above with respect to the first and second mixing devices 3A, 3B.

[0125] The vaporized refrigerant is sent to various stages of the compressor K1 in the respective refrigerant flow paths and compressed, and then condensed by exchanging heat with an external cooling fluid, such as water or air, in a condenser. The stream resulting from the condenser is returned to the additional exchanger 2. The pressure of the first cooling stream at the outlet of the compressor K1 can range from 2 MPa to 6 MPa. The temperature of the additional cooling stream at the outlet of the condenser C1 can range from 10 °C to 45 °C.

[0126] Preferably, the refrigerant flows upward in the longitudinal direction z from one end 2b to the other end 2a of the additional exchanger 2. The end 2b corresponds to the low-temperature end of the additional exchanger 2, where the refrigerant is introduced at the lowest temperature of the temperature of the additional exchanger 2.

[0127] Of course, the present invention is not limited to the specific examples described and illustrated in this application. Other alternative embodiments or embodiments within the capabilities of those skilled in the art may also be considered without departing from the scope of the present invention. For example, other forms for injecting and withdrawing fluid from the exchanger, other courses and directions of fluid flow, other types of fluid, other forms of mixing devices, lateral and longitudinal channels, etc., may be clearly considered depending on the constraints imposed by the method to be implemented.

Claims

1. A heat exchanger (1) comprising a plurality of plates (2) arranged parallel to each other and in the longitudinal direction (z), wherein the plates (2) are stacked spaced apart so that a first fluid (F1) flows entirely in the longitudinal direction (z). At least one first set of flow paths (10A, 10B) configured as such, and at least one second set of flow paths (20) configured to provide a heat exchange relationship with the first fluid (F1) in the flow of a second fluid (F2). Together to define, at least one first flow path (10A) of the first set includes a first mixing device (3A), and at least one second flow path (10B) of the first set includes a second mixing device (3B), each of the first and second mixing devices (3A, 3B) being: - At least one lateral channel (31A, 31B) configured such that a first phase (61) of the first fluid (F1) flows from at least one first inlet (311A, 311B); - A series of longitudinal channels (32A, 32B) each extending in the longitudinal direction (z) and configured such that a second phase (62) of the first fluid (F1) flows from a second inlet (321A, 321B) to a second outlet (322A, 322B), the series of longitudinal channels being continuous with each other in a lateral direction (y) perpendicular to the longitudinal direction (z); and - At least one opening (34) fluidly connecting the at least one lateral channel (31A, 31B) to the at least one longitudinal channel (32A, 32B), the first and second mixing devices (3A, 3B) being configured to distribute a mixture of the first phase (61) and the second phase (62) via the second outlet (322A, 322B) of their respective longitudinal channels (32A, 32B). At least one opening (34) Including, in a heat exchanger, The longitudinal channel (32A) of the first mixing device (3A) is at least partially arranged at a plurality of positions in the lateral direction (y) different from the position of the longitudinal channel (32B) of the second mixing device (3B), The second mixing device (3B) includes two longitudinal edges (3e) extending parallel to the longitudinal direction (z), and each longitudinal channel (32A) of the first mixing device (3A) is, in the transverse direction (y), between two consecutive longitudinal channels (32B) of the second mixing device (3B), or between a longitudinal channel (32B) and a longitudinal edge (3e) of the second mixing device (3B). A single longitudinal channel (32A) of the first mixing device (3A) is, in the transverse direction (y), between two consecutive longitudinal channels (32B) of the second mixing device (3B), or between a longitudinal channel (32B) and a longitudinal edge (3e) of the second mixing device (3B). The position in the transverse direction (y) of the longitudinal channel (32B) of the second mixing device (3B) coincides with the position in the transverse direction (y) of the longitudinal channel (32A) of the first mixing device (3A) after a 180° rotation in a plane defined by the transverse direction (y) and the longitudinal direction (z). The heat exchanger (1) is characterized by this.

2. The longitudinal channel (32A) of the first mixing device (3A) is separated from each other by a first constant distance (D Ａ ), and the longitudinal channel (32B) of the second mixing device (3B) is separated from each other by a second constant distance (D Ｂ ), preferably the first distance (D Ａ ) and the second distance (D Ｂ ) are equal, and the heat exchanger according to claim 1 is characterized in that.

3. The series of longitudinal channels (32B) of the second mixing device (3B) are offset from the series of longitudinal channels (32A) of the first mixing device (3A) by an offset distance (D ｙ ) measured in the transverse direction (y), and preferably, the offset distance (D ｙ ) is 25 to 75% of the first distance (D Ａ ), and preferably, the offset distance (D ｙ ) is 50% of the first distance (D Ａ ). The heat exchanger according to claim 2, characterized in that it is

4. The first distance (D Ａ ) and / or the second distance (D Ｂ ) ranges from 10 to 40 mm, and preferably is 20 mm or more and 30 mm or less, a heat exchanger according to claim 2 or 3.

5. A heat exchanger according to any one of claims 1 to 4, comprising a plurality of alternately arranged first flow paths (10A) and second flow paths (10B), wherein at least one flow path (20) of the second set is arranged between at least one first flow path (10A) and at least one second flow path (10B) following the at least one first flow path (10A).

6. The heat exchanger according to any one of claims 1 to 5, wherein the transverse channels (31) and / or the longitudinal channels (32) of the first mixing device (3A) and the second mixing device (3B) are straight lines.

7. The heat exchanger according to any one of claims 1 to 6, wherein the first and second mixing devices (3) each include a series of transverse channels (31A, 31B) extending in the transverse direction (y) and being consecutive to each other in the longitudinal direction (z).

8. A method for liquefying a stream containing a hydrocarbon (102) such as natural gas as a second fluid (F2), the method having at least one heat exchanger (1) according to any one of claims 1 to 7 attached thereto, and:[[]] a) introducing the hydrocarbon stream (102) into the second set of the flow paths (20); step; b) introducing a cooling stream (202) into a third set of flow paths of the heat exchanger (1); c) discharging the cooling stream (201) from the heat exchanger (1) and expanding the cooling stream (201) to at least one pressure level to generate at least one two-phase cooling stream (203) as the first fluid (F1); d) separating at least a portion of the two-phase cooling stream (203) resulting from step c) into a gas phase (62) and a liquid phase (61); e) introducing at least a portion of the gas phase (62) and at least a portion of the liquid phase (61) into the first flow path (10A) and the second flow path (10B) of the first set respectively via separate inlets (311A, 321A, 311B, 321B) of the first flow path (10A) and the second flow path (10B); f) passing the phases (61, 62) introduced in step e) through the first and second mixing devices (3A, 3B) such that at the respective outlets of the first and second mixing devices (3A, 3B), the first fluid (F1) is obtained as a mixture of the first phase (61) and the second phase (62); g) vaporizing at least a portion of the first fluid (F1) resulting from step f) in the first and second flow paths (10A, 10B) by exchanging heat with at least the hydrocarbon stream (102) to obtain a cooled and / or at least partially liquefied hydrocarbon stream (101) at the outlet of the heat exchanger (1). A method comprising the above steps.

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