Mixing device, heat exchange apparatus and related mixing method promoting uniform distribution of a biphasic mixture

Abstract

The present invention relates to a heat exchange assembly comprising: a heat exchanger (1) having a plate (2); a source of a first phase (61) of a first fluid (F1) fluidly connected to at least one first manifold (30) of the heat exchanger (1); a source of a second phase (62) of the first fluid (F1) fluidly connected to at least one second manifold (52) of the heat exchanger (1); and a mixing device (3) for distributing a mixture of the first phase (61) and the second phase (62) of the first fluid (F1) generally along a longitudinal direction (z) into at least one passage (10) of the heat exchanger (1), the mixing device (3) comprising at least one lateral passage (31) and a series of longitudinal passages. (32) and at least one opening (34), the lateral channels being configured for the first phase (61) of the first fluid (F1) to flow from at least one first inlet (311), the longitudinal channels extending in the longitudinal direction (z) and each configured for the second phase (62) of the first fluid (F1) to flow from a second inlet (321) to a second outlet (322), the longitudinal channels being sequentially arranged in a lateral direction (y) orthogonal to the longitudinal direction (z), the opening fluidly connecting the lateral channels (31) to at least one longitudinal channel (32), such that the mixing device (3) is configured to dispense a mixture of the first phase (61) and the second phase (62) via the second outlet (322) of the at least one longitudinal channel (32). According to the invention, the at least one longitudinal channel (32) is divided in the longitudinal direction (z) into at least one upstream portion (323) and a downstream portion (324), the upstream portion and the downstream portion each having a length (L3, L4) measured in the longitudinal direction (z) and a width (D3, D4) measured in the lateral direction (y). y The downstream portion (324) is arranged between the upstream portion (323) and the second outlet (322), and the width (Dy) of the downstream portion (324) at any point along its length (L4) is greater than the width (D3) of the upstream portion (323).

Description

[0001] The present invention relates to a mixing device for more uniformly distributing a liquid / gas two-phase mixture in at least one passage of a heat exchanger, and to a heat exchange device including such a mixing device.

[0002] In particular, the present invention can be applied to heat exchangers that vaporize at least one stream of a liquid-gas mixture (especially a stream of a liquid-gas mixture having multiple constituent elements, such as a mixture containing hydrocarbons) by heat exchange with at least one other fluid, such as cooled or even at least partially liquefied natural gas, or even supercooled liquefied natural gas.

[0003] Among methods using one or more fluid refrigeration cycles with a two-phase coolant (i.e., in a liquid / gas mixture state), several methods are known for liquefying a natural gas stream to obtain liquefied natural gas (LNG). Typically, a cooling stream (usually a mixture of multiple constituent elements, such as a mixture containing hydrocarbons) is compressed by a compressor and then introduced into one or more exchangers, where the cooling stream is completely liquefied and subcooled to the coldest temperature reached by the cooling fluid in this method, typically the coldest temperature of the LNG stream. At the coldest outlet of the exchanger, the cooling stream expands by forming a first phase and a second phase. These two phases are separated by a phase separator and then reintroduced into the exchanger, where they are remixed before being reintroduced. The cooling stream introduced into the exchanger in a two-phase state vaporizes against the liquefied hydrocarbon stream and against the natural gas stream. One such known method is described in document WO-A-2017 / 081374.

[0004] Brazed plates and finned aluminum exchangers were used to allow for a very compact unit that provides a large exchange surface, thereby improving the energy performance capability of the method, and doing so within a limited volume.

[0005] These exchangers comprise a stack of plates extending in both length and width, thus forming a stack of multiple sets of passages positioned vertically to each other. Some of these passages are used to circulate heat transfer fluids (e.g., hydrocarbon streams to be liquefied), while others are used to circulate coolants (e.g., two-phase cooling streams to be vaporized).

[0006] Heat exchange structures (such as heat exchange corrugations) are typically arranged in these passages of the exchanger. These structures include fins extending between the plates of the exchanger and allow for an increase in the heat exchange surface area of ​​the exchanger. They also act as spacers and contribute to the mechanical strength of the passages.

[0007] Some problems can arise in exchangers that implement two-phase cooling flows, especially when their vaporization occurs in the rising vertical direct current.

[0008] In fact, to ensure proper operation of the exchanger, and especially to maximize the use of the exchange surface of the exchanger (particularly for exchangers implementing liquid-gas mixtures), the ratio of the liquid phase to the gas phase must be the same in all passages and must be uniform in the same passage.

[0009] The dimensions of the exchanger are calculated under the assumption that the phases are uniformly distributed and therefore the liquid phase in each passage has a single temperature (equal to the dew point of the mixture) at the end of vaporization.

[0010] Especially for mixtures with multiple constituent elements, the endpoint of the vaporization temperature will depend on the ratio of the liquid and gas phases in the pathway, since the two phases do not have the same composition.

[0011] When the two phases are unevenly distributed, the temperature profile of the first fluid will therefore vary depending on the path and / or within the same path. Due to this uneven distribution, one or more fluids that have an exchange relationship with the two-phase mixture may have an exchanger outlet temperature higher than expected, which thus reduces the performance capability of the heat exchanger.

[0012] One solution for distributing the liquid and gas phases of a mixture as uniformly as possible involves introducing them separately into an exchanger and then mixing them together only after they are inside the exchanger.

[0013] Documents FR-A-2563620 or WO-A-2018 / 172644 describe such an exchanger in which a grooved rod is inserted into a series of passages for guiding a two-phase mixture. This mixing device includes a series of separate channels or grooves for the liquid phase flow of the coolant and another series of separate channels for the gas phase flow of the coolant. One series of channels is fluidly connected to the other series of channels via openings, such that the liquid-gas mixture (i.e., two-phase flow) is distributed from the mixing device toward the heat exchange area. Each coolant passage of the exchanger is provided with such a device.

[0014] One problem with this type of mixing device is the uneven distribution of the liquid-gas mixture across the width of the exchanger passage.

[0015] In practice, the two-phase mixture is distributed at the outlet of the channel in the inlet passage. Because the channels are arranged at intervals, the width of the liquid-gas mixture across the passage is discretely introduced into the exchange zone. As the fluid flows in the exchanger along the overall flow direction, distribution can be achieved, particularly by means of exchange corrugations (such as perforated corrugations or sawtooth corrugations) commonly used in this type of exchanger, in a direction orthogonal to the overall flow direction. Therefore, "sawtooth" corrugations tend to deflect a portion of the fluid away from its flow direction, and perforated corrugations fluidly connect the channels formed by the corrugations.

[0016] However, uniform fluid distribution across the width of the exchanger can only be achieved after the mixture has traveled a certain distance away from the mixing device. At this distance, depending on the location considered across the exchanger width, the fluid is supplied to the exchange zone at a non-uniform mass flow rate, and some channels of the exchange corrugations may have only a limited supply or even no supply. This reduces the exchanger's performance capability. Furthermore, this distribution, achieved through lateral deflection of the fluid, is impossible with straight, unperforated corrugations.

[0017] Exchangers operating with low temperature deviations between the heat transfer fluid and the coolant fluid are more sensitive to this poor distribution phenomenon. Furthermore, the uneven distribution is even more pronounced when the coolant mixture contains multiple constituent elements.

[0018] Existing solutions are unsatisfactory. Therefore, placing free space at the outlet of the mixing unit causes problems with the mechanical strength of the exchanger and leads to the accumulation of the first phase in that area. Increasing the number of successive channels across the exchanger width reduces the flow rate of the first phase through each opening of each channel and is detrimental to the proper distribution of the two-phase mixture at the mixing unit outlet. Finally, a "hard-channel" corrugated arrangement at the mixing unit outlet or an arrangement of the mixing unit with more complex geometry increases pressure loss, which reduces the performance capability of the method.

[0019] The object of the present invention is to solve all or some of the above-mentioned problems, particularly by providing a mixing device that provides a more uniform distribution of the two-phase mixture across the width of the heat exchanger passage while limiting the pressure loss that the two-phase mixture may experience at the outlet of the mixing device.

[0020] The solution according to the invention also relates to a mixing device for distributing a mixture of a first phase and a second phase of a first fluid generally in a longitudinal direction in at least one passage of a heat exchanger, said mixing device comprising:

[0021] - At least one lateral channel, which is configured for the first phase of the first fluid to flow from at least one first inlet;

[0022] - A series of longitudinal channels extending in a longitudinal direction, each configured for the flow of a second phase of the first fluid from a second inlet to a second outlet, the longitudinal channels being sequentially arranged in lateral directions orthogonal to the longitudinal direction; and

[0023] - At least one opening fluidly connects the lateral channel to at least one longitudinal channel, such that the mixing device is configured to dispense a mixture of a first phase and a second phase via a second outlet of the at least one longitudinal channel, characterized in that the at least one longitudinal channel of the mixing device is divided into an upstream portion and a downstream portion in the longitudinal direction, the upstream portion and the downstream portion each having a length measured in the longitudinal direction and a width measured in the lateral direction, the downstream portion being arranged between the upstream portion and the second outlet, the width of the downstream portion at any point in its length being greater than the width of the upstream portion.

[0024] Where applicable, the present invention may include one or more of the following features:

[0025] -The downstream portion has a width that increases along its length toward the second outlet, preferably a continuously increasing width;

[0026] -The downstream portion has a minimum width and a maximum width, where the ratio D M / D m Greater than or equal to 1.1, preferably greater than or equal to 1.8 and / or less than or equal to 4;

[0027] - In a plane parallel to the longitudinal and lateral directions, the downstream portion, either entirely or partially, has an external profile in the form of an isosceles trapezoid as a longitudinal section.

[0028] - In a plane parallel to the longitudinal and lateral directions, the downstream portion, either entirely or partially, has a curved external profile as a longitudinal section.

[0029] - The downstream portion appears at the downstream face of the mixing device, and the outer profile forms an angle between 5° and 85°, which is measured between the tangent line tangent to the outer profile at the intersection with the downstream face and the axis of symmetry of the longitudinal channel.

[0030] - The upstream portion of the longitudinal channel is connected to the downstream portion through an end, and the at least one opening appears in the longitudinal channel at a distance from the end in the upstream portion, preferably greater than or equal to 4% of the length of the upstream portion and preferably in the range of 7% to 90% of the length of the upstream portion;

[0031] - At least one opening is arranged such that when the first phase flows from the first inlet of the lateral channel and the second phase flows from the second inlet of the longitudinal channel, the mixing of the first phase and the second phase occurs upstream of the downstream portion;

[0032] - These one or more openings of the mixing device appear at the upstream portion of the longitudinal channel;

[0033] - Each of the series of longitudinal channels includes at least one opening that appears in its upstream portion, the position of which varies along the longitudinal direction between these longitudinal channels;

[0034] - The lengths of the upstream and downstream portions are such that the ratio L3 / L4 is between 1 and 15, preferably between 3 and 12;

[0035] - In a plane parallel to the longitudinal and lateral directions, the upstream portion has a straight outer profile of constant width as a longitudinal section, either entirely or partially, which is preferably equal to the minimum width of the downstream portion.

[0036] - The downstream portion has a depth measured in a direction called the stacking direction, which increases toward the second outlet, and this direction is perpendicular to the longitudinal direction and perpendicular to the lateral direction;

[0037] - The longitudinal channel includes at least one obstacle arranged to subdivide the downstream portion into a plurality of intermediate channels that appear at the second exit, preferably, the intermediate channels being arranged symmetrically with respect to the axis of symmetry of the longitudinal channel.

[0038] - At the second outlet, the total surface of the at least one obstacle, measured in a cross-sectional plane perpendicular to the longitudinal direction, is between 20% and 80%, preferably between 30% and 70%, of the total fluid flow through the downstream portion of the surface measured in the cross-sectional plane.

[0039] - The width of the at least one obstacle, measured in the lateral direction, increases toward the second exit, wherein the at least one obstacle preferably has a curved outer profile along the longitudinal cross-sectional plane;

[0040] - The longitudinal channels further include at least one balancing channel that fluidly connects these intermediate channels.

[0041] Furthermore, the present invention relates to a heat exchanger comprising a plurality of plates arranged parallel to each other and parallel to a longitudinal direction, the plates being stacked at intervals to define together at least one first set of passages and at least one second set of passages, the first set of passages being configured for a first fluid to generally flow in the longitudinal direction, and the second set of passages being configured for a second fluid to flow to form a heat exchange relationship with the first fluid, wherein at least one passage in the first set includes a mixing device according to the invention.

[0042] Furthermore, the present invention relates to a heat exchange device comprising:

[0043] - A heat exchanger comprising a plurality of plates arranged parallel to each other and parallel to the longitudinal direction, the plates being stacked in a spaced-out manner to define together at least one first set of passages and at least one second set of passages, the first set of passages being configured for a first fluid to flow generally in the longitudinal direction, and the second set of passages being configured for a second fluid to flow to form a heat exchange relationship with the first fluid.

[0044] - A source of a first phase of a first fluid, which is fluidly connected to at least one first manifold of a heat exchanger;

[0045] - A source of the second phase of the first fluid, which is fluidly connected to at least one second manifold of the heat exchanger;

[0046] - According to the mixing device of the invention, the mixing device is arranged in at least one passage of a first series and configured to dispense a first fluid formed by a mixture of a first phase and a second phase in the first series of passages, a first inlet of a lateral passage being in fluid communication with a first manifold and a second inlet being in fluid communication with a second manifold, the first phase being a liquid phase and the second phase being a gas phase.

[0047] Preferably, the first phase is a liquid phase, and the second phase is a gas phase.

[0048] According to another aspect, the present invention relates to a method for mixing a first phase and a second phase of a first fluid in a mixing apparatus according to the invention, the method comprising the following steps:

[0049] i) Introducing the first phase of the first fluid through at least one first inlet in the lateral channel;

[0050] ii) A second phase of the first fluid is introduced via a second inlet of each longitudinal channel, the second phase flowing longitudinally in each longitudinal channel to a second outlet of the longitudinal channel;

[0051] iii) Allow at least a portion of the first phase to flow from the lateral channel through the opening toward the longitudinal channel, so as to mix the first phase with the second phase in the longitudinal channel;

[0052] iv) Distribute the mixture of the first and second phases via the second outlet of each longitudinal channel.

[0053] Preferably, the first phase is mixed with the second phase upstream of the downstream portion.

[0054] Furthermore, the present invention also relates to a method for liquefying a hydrocarbon stream, such as natural gas, as a second fluid by heat exchange with at least one two-phase cooling stream as a first fluid, said method implementing the mixing method according to the present invention, and comprising the following steps:

[0055] a) Introduce the hydrocarbon stream into the second set of passages of the heat exchanger;

[0056] b) Introduce the cooling flow into the third set of passages of the heat exchanger;

[0057] c) Discharge the cooling flow from the heat exchanger and expand the cooling flow to at least one pressure level to generate at least one two-phase cooling flow;

[0058] d) Separate at least a portion of the two-phase cooling flow originating from step c) into a second phase and a first phase;

[0059] e) Arrange a mixing device in at least one passage of the first set of passages of the heat exchanger;

[0060] f) Introducing at least a portion of the second phase and at least a portion of the first phase into a mixing device so as to obtain a first fluid formed by the mixture of the first phase and the second phase at the outlet of the mixing device;

[0061] g) By exchanging heat with at least the hydrocarbon stream, at least a portion of the first fluid originating from step f) is vaporized in the passage, thereby obtaining a cooled and / or at least partially liquefied hydrocarbon stream at the outlet of the exchanger.

[0062] The term "natural gas" refers to any composition containing hydrocarbons (including at least methane). This includes "raw" compositions (before any treatment or washing) as well as any compositions that have been partially, substantially, or completely treated to reduce and / or eliminate one or more compounds (including, but not limited to, sulfur, carbon dioxide, water, mercury, and certain heavy aromatics).

[0063] The invention will now be better understood through the following description, given only by non-limiting example and with reference to the accompanying drawings, in which:

[0064] Figure 1 A heat exchange device according to an embodiment of the present invention is illustrated schematically;

[0065] Figure 2 This is a three-dimensional schematic diagram of a mixing device according to an embodiment of the present invention;

[0066] Figure 3 This is a schematic cross-sectional view of a first mixing device according to an embodiment of the present invention in a plane perpendicular to the plate of the exchanger;

[0067] Figure 4 This is a schematic longitudinal cross-sectional view of a mixing device according to an embodiment of the present invention in a plane parallel to the longitudinal direction z and the lateral direction y.

[0068] Figure 5 This is a schematic longitudinal cross-sectional view of the mixing device according to another embodiment of the present invention in a plane parallel to the longitudinal direction z and the lateral direction y;

[0069] Figure 6 This is a schematic longitudinal cross-sectional view of the mixing device according to another embodiment of the present invention in a plane parallel to the longitudinal direction z and the lateral direction y;

[0070] Figure 7 This is a schematic longitudinal cross-sectional view of the mixing device according to another embodiment of the present invention in a plane parallel to the longitudinal direction z and the lateral direction y;

[0071] Figure 8 This is a schematic longitudinal cross-sectional view of the mixing device according to another embodiment of the present invention in a plane parallel to the longitudinal direction z and the lateral direction y;

[0072] Figure 9 This is a schematic longitudinal cross-sectional view of the mixing device according to another embodiment of the present invention in a plane parallel to the longitudinal direction z and the lateral direction y;

[0073] Figure 10 The configuration of the mixing device and exchanger according to the invention for performing fluid flow simulation is shown;

[0074] Figure 11 The results of fluid flow simulations of a mixing device configured according to the prior art and a mixing device according to an embodiment of the present invention are shown;

[0075] Figure 12 A method for liquefying a hydrocarbon stream according to an embodiment of the present invention is illustrated schematically;

[0076] Figure 13 A method for liquefying a hydrocarbon stream according to another embodiment of the present invention is illustrated schematically;

[0077] Figure 1This is a cross-sectional view of a heat exchanger 1 including a mixing device 3 according to the present invention. The exchanger 1 is preferably of the type having brazed plates and fins. It comprises a stack of plates 2 (not shown) extending in two dimensions parallel to a plane defined by a longitudinal direction z and a lateral direction y. The plates 2 are arranged vertically parallel and spaced apart, thus forming a stack of passageways for fluid flow through the plates in an indirect heat exchange relationship.

[0078] Preferably, each passage has a flattened parallelepiped shape. The gap between two successive plates is small compared to the length of each passage measured in the longitudinal direction z and the width measured in the lateral direction y.

[0079] The exchanger 1 may include more than 20 or even more than 100 plates that together define a first set of passages 10 for guiding at least one first fluid F1. Figure 1 The diagram shows a single pathway and a second set of pathways 20 for guiding at least one second fluid F2. Figure 1 (Not shown in the image), the flow of the fluid generally occurs along the z-direction. Passages 10 may be arranged all or partly alternately and / or adjacent to all or some of the passages 20. The exchanger 1 may include a third set of passages or even more for the flow of one or more additional fluids. These sets of passages are stacked relative to each other, forming a passage stack.

[0080] The sealing of passages 10 and 20 along the edge of plate 2 is typically provided by lateral sealing strips and longitudinal sealing strips 4 attached to plate 2. The lateral sealing strips 4 do not completely seal passages 10 and 20, but advantageously leave fluid inlet and outlet openings at diagonally opposite corners of the passages.

[0081] The openings of the first group of passages 10 are arranged so that they overlap vertically along the stacking direction x, which is perpendicular to the directions y and z, while the openings of the second group of passages 20 are arranged in... Figure 1 The other corners of the exchanger, indicated by the middle arrow F2, have inlets and outlets for the second fluid F2 located on the top left and bottom right, respectively. The upper and lower openings are joined in semi-tubular manifolds 40, 45, 52, and 55, through which fluid is distributed to and discharged from passages 10 and 20.

[0082] It should be noted that, except for Figure 1 Other configurations for introducing and discharging fluid besides those shown. Therefore, the openings of the passage can be arranged at other locations along the width of the exchanger, particularly at the center of the exchanger width, and / or at other locations along the length of the exchanger.

[0083] exist Figure 1In the diagram, semi-tubular manifolds 52 and 45 are used to introduce fluid into exchanger 1, and semi-tubular manifolds 40 and 55 are used to discharge this fluid from exchanger 1.

[0084] In this alternative embodiment, the manifold supplying one fluid and the manifold discharging another fluid are located at the same end of the exchanger, so fluids F1 and F2 flow through exchanger 1 in opposite directions.

[0085] According to another alternative embodiment, the first fluid and the second fluid can also circulate in the same direction, wherein the device for supplying one fluid and the device for discharging the other fluid are located at opposite ends of the exchanger 1.

[0086] Preferably, when the exchanger 1 is operating, the z-direction is vertically oriented. The first fluid F1 flows vertically upwards overall. Other flow directions and routes for fluids F1 and F2 are obviously conceivable without departing from the scope of the invention.

[0087] It should be noted that, within the scope of this invention, one or more second fluids F2 with different properties may flow within the second set of passages 20.

[0088] Preferably, the first fluid F1 is a coolant, and the second fluid F2 is a heat transfer fluid.

[0089] The exchanger advantageously includes distribution corrugations 51, 54, which are arranged in the form of corrugated sheets between two successive plates 2, extending from the inlet opening and the outlet opening. Distribution corrugations 51, 54 ensure uniform distribution and recovery of fluid across the entire width of passages 10, 20.

[0090] Furthermore, passages 10 and 20 advantageously include heat exchange structures arranged between plates 2. The purpose of these structures is to increase the heat exchange surface of the exchanger and to increase the exchange coefficient between fluids by making the flow more turbulent. In practice, the heat exchange structures come into contact with the fluid circulating in the passages and transfer heat to adjacent plates 2 by conduction. The heat exchange structures can be brazed to these adjacent plates, which increases the mechanical strength of the exchanger.

[0091] The heat exchange structures also serve as spacers between the plates 2, particularly when the exchanger is assembled by brazing, and to prevent any deformation of the plates when pressurized fluid is applied. These heat exchange structures also guide the fluid flow within the exchanger's passageways.

[0092] Preferably, these structures include heat exchange corrugations 11 that advantageously extend parallel to the width and length of the plates 2 across the passages 10, 20, along the length of the distribution corrugations. Thus, the main portion of the length of the passages 10, 20 of the exchanger forms the heat exchange section itself, which is lined with the heat exchange structure, the main portion being bounded by the distribution section lined with distribution corrugations 51, 54.

[0093] Figure 1 A first set of passages 10 is shown, configured for the flow of a first fluid F1 in the form of a two-phase mixture, also referred to as a two-phase mixture. The first set comprises multiple such passages 10 stacked vertically. The first fluid F1 is separated into a first phase 61 and a second phase 62 in a separator device 6, which are respectively introduced into an exchanger 1 via separate first manifolds 30 and second manifolds 52. The separator 6 then forms the first and second phase sources. The term "fluid source" refers to any device suitable for supplying fluid to the channels of the mixing device.

[0094] Preferably, the first phase 61 is a liquid, and the second phase 62 is a gas. With the longitudinal channel configured for the vertical upward flow of the first phase and the two-phase mixture at the second outlet, the effect of gravity on the flow of the gas phase is smaller than its effect on the flow of the liquid phase. The higher velocity of the gas phase is beneficial for the transport of the liquid phase in the opening 34. Furthermore, once the liquid phase has been introduced into the longitudinal channel via the opening 34, the presence of the gas phase promotes the flow of the liquid phase.

[0095] Phases 61 and 62 are then mixed together by a mixing device 3 arranged in at least one passage 10. Advantageously, several or even all of the passages 10 in the first group include the mixing device 3. Semi-tubular manifolds 52 and 55 are fluidly connected to the inlet and outlet of the passage 10. A first manifold 30 is fluidly connected to at least one first inlet 311 of the mixing device 3. A second manifold 52 is fluidly connected to at least one second inlet 321 of the mixing device 3. The first and second manifolds can be any manifold device adapted to collect fluid from a fluid source and introduce said fluid into one or more passages of a heat exchanger.

[0096] It should be noted that Figure 1 A mixing device 3 is shown positioned at a distance from the distribution area 51 of the exchanger 1. According to an alternative embodiment, the mixing device 3 may be positioned directly after or alongside the distribution area, meaning the mixing device and the distribution area are a single unit. In the latter possibility, the mixing device forms a single-piece component, which can be manufactured by conventional machining or by additive manufacturing (i.e., by 3D printing, for example by laser sintering).

[0097] Figure 2 It is a three-dimensional view of the mixing device 3 housed in the passage 10, which is advantageously constructed of rods or bars.

[0098] The mixing device 3 preferably extends across almost the entire or even the entire height of the passage 10 into the cross section of the passage 10, such that the mixing device contacts each plate 2 forming the passage 10.

[0099] The mixing device 3 is advantageously attached to the plate 2 by brazing.

[0100] The mixing device 3 has an overall parallelepiped shape.

[0101] Preferably, the mixing device 3 is a one-piece component, i.e., formed from a block or as a single piece. The mixing device 3 can be manufactured by conventional machining or by additive manufacturing. The mixing device 3 may have a first dimension parallel to the longitudinal direction z in the range of 20 mm to 200 mm, and a second dimension parallel to the lateral direction y in the range of 100 mm to 1400 mm.

[0102] The mixing device 3 includes at least one lateral channel 31 configured for the first phase 61 of the first fluid F1 to flow from at least one first inlet 311. Preferably, the lateral channel 31 extends parallel to the lateral direction y.

[0103] The mixing device further includes a series of longitudinal channels 32 extending parallel to the longitudinal direction z and configured for the second phase 62 of the first fluid F1 to flow upward from the second inlet 321 to the second outlet 322. The longitudinal channels 32 are arranged at successive positions y in the lateral direction y. i y i+1 ...place.

[0104] Preferably, the lateral channel 31 extends across the entire second dimension, and / or the longitudinal channel 32 extends across the entire first dimension.

[0105] Preferably, the mixing device 3 includes at least one first inlet 311 in fluid communication with a first manifold 30, and a second inlet 321 separate from (i.e., different from) the first inlet 311 and in fluid communication with a second manifold 52. The first manifold 30 is fluidly connected to a first phase source 61, and the second manifold 52 is fluidly connected to another second phase source 62. The at least one first inlet 311 and the at least one second inlet 321 are in fluid communication via at least one opening 34. In fact, the mixing device is configured to separately introduce the first phase and the second phase, wherein the first inlet 311 is adapted to supply a lateral channel 31 with the first phase 61, and the at least one second inlet 321 is adapted to supply a longitudinal channel 32 with the second phase 62.

[0106] The first and second inlets are advantageously formed by making lateral and longitudinal channels appear at the lateral and longitudinal outer edges of the device 3.

[0107] Figure 2 The introduction of the first phase 61 via an end of the device 3, comprising a plurality of first inlets 311, is illustrated. According to an advantageous embodiment, the mixing device 3 includes at least one additional first inlet for the first phase 61 located at the opposite end of the device 3. Advantageously, these additional inlets are obtained by extending lateral channels 31 until they appear at the opposite lateral edges of the exchanger 1. In this case, another first manifold 30 is arranged on the opposite side of the exchanger 1. Introducing the first phase 61 on either side of the mixing device allows for a reduction in the effect of pressure loss as the first phase flows in the lateral channels, which promotes a more uniform distribution of the two-phase mixture across the width of the exchanger.

[0108] Preferably, the mixing device 3 includes a mixing volume located in a longitudinal channel 32, which is downstream of the opening 34 in the flow direction of the first phase 61.

[0109] The lateral channel 31 is fluidly connected to at least one longitudinal channel 32, such that when the first phase 61 flows in the lateral channel 31 and the second phase 62 flows in the longitudinal channel 32, the mixing device 3 distributes a mixture of the first phase 61 and the second phase 62, preferably a liquid / gas two-phase mixture F1 (also referred to as a two-phase mixture), via a second outlet 322 of the channel 32. Preferably, the longitudinal channel and / or the lateral channel are generally straight.

[0110] Channels 31 and 32 are advantageously shaped as longitudinal recesses within the mixing device 3. These channels preferably appear on the upper surface 3a and lower surface 3b of the mixing device 3.

[0111] Preferably, channels 31 and 32 have a square or rectangular cross-section, but alternatively, they may take other shapes (circular, circular portions, etc.).

[0112] The opening 34 is advantageously a perforation 34 formed in the material of the device 3, and preferably extends between the first channel 31 and the second channel 32 in a plane formed by the directions x and y, wherein the opening 34 can be tilted relative to the direction x, or preferably aligned with the vertical direction x. Preferably, the opening 34 has cylindrical symmetry, and more preferably is cylindrical.

[0113] Preferably, the at least one lateral channel 31 includes a bottom wall 3c, and the at least one longitudinal channel 32 includes a top wall 3d that extends opposite to the bottom wall 3c, and an opening 34 is a perforation in the bottom wall of the first channel 31 and appears in the top wall of the longitudinal channel 32.

[0114] Figure 3 yes Figure 2 The view of the mixing device 3 in a cross-sectional plane orthogonal to the lateral direction y and passing through the opening 34.

[0115] According to existing technology, a mixing device 3 is arranged in the passage 10 of the first group. This mixing device has a longitudinal channel whose width, measured along the lateral direction y, remains constant in the longitudinal direction z, particularly in a parallelepiped shape (e.g.,...). Figure 2 The longitudinal channel (shown as the shape of the lateral channel 31).

[0116] At the outlet of each longitudinal channel 32, the flow of the two-phase mixture of the first fluid F1 preferably occurs in the longitudinal direction z, while the flow gradually expands across the width of the passage 10. Homogenization of these flows in each passage is achieved only beyond a certain distance covered by the mixture. This homogenization of the mixture F1 is lacking throughout the entire stack of passages 10 in the first group.

[0117] To address these issues, the present invention proposes arranging a mixing device 3 in the first set of pathways 10 such that at least one longitudinal channel 32 of the mixing device is divided into an upstream portion 323 and a downstream portion 324 along the longitudinal direction z. Each of the upstream and downstream portions has a length L3, L4 measured along the longitudinal direction z and a width D3, D4 measured parallel to the lateral direction y. y The downstream portion 324 is arranged between the upstream portion 323 and the second outlet 322. According to the invention, the downstream portion 324 has a width D at any point along its length L4. y This width is (strictly) greater than the width D3 of the upstream portion 323.

[0118] It should be noted that the term "width" is understood to refer to the distance measured between the edges defining the longitudinal channel 32 within a predetermined longitudinal cross-sectional plane parallel to the longitudinal direction z and parallel to the lateral direction y, i.e., for example, as... Figures 4 to 9 The width of the outer contour of the channel within the cross-sectional plane is shown.

[0119] Arranging the downstream section to widen laterally promotes lateral expansion of the two-phase mixture exiting the longitudinal channel 32. The inventors of this invention have demonstrated that the fluid jet forms a wide-bottomed cone at the outlet of the longitudinal channel, which allows the fluid exiting the longitudinal channel 32 to flush a larger number of exchange channels of the exchange corrugations located downstream of the mixing device 3 during operation. Therefore, it is possible to achieve faster homogenization using the fluid jet exiting the adjacent longitudinal channel.

[0120] Therefore, after the mixture has traveled a shorter distance downstream of the mixing device 3, the difference in mixing rate across the width of the passage 10 is reduced, or even eliminated. This improves the heat exchange between the two-phase mixture and the second fluid F2, and thus improves the operation of the exchanger.

[0121] Furthermore, when the mass flow rate of the two-phase mixture in the longitudinal channel 32 is relatively high, widening the downstream section in the lateral direction y provides the possibility of slowing down the flow of the mixture in the downstream section, and thus provides the possibility of reducing the pressure loss experienced by the two-phase mixture at the outlet of the longitudinal channel 32 when the two-phase mixture flushes the exchange corrugations located downstream of the mixing device 3.

[0122] Preferably, some, and preferably all, of the longitudinal channels 32 are configured according to the invention and may include all or some of the features described below.

[0123] Preferably, the downstream portion 324 appears at the downstream face 326 of the mixing device 3, and the second outlet 322 is located at the downstream face 326. At least a portion of the first phase 61 flowing into the lateral channel 31 is supplied to the opening 34 so as to flow into the longitudinal channel where mixing occurs. The second phase 62 flows successively into the upstream portion 323 and the downstream portion 324. The mixture is distributed via the second outlet 322.

[0124] Preferably, the downstream portion 324 has a width D that increases across length L4 toward the second outlet 322. y Preferably, it is increased over the entire length L4.

[0125] It should be noted that the widening of the downstream portion along the longitudinal direction z can be carried out once or multiple times, or even gradually, on a special basis (i.e., continuously increasing along all or part of the downstream portion 324).

[0126] Preferably, the width D of the downstream portion 324 y The width increases continuously along the entire length L4 toward the second outlet 322, i.e., gradually. Therefore, the interruptions that could cause sudden changes in channel width in the mixed flow are limited.

[0127] Preferably, the downstream portion 324 has a minimum width D m and maximum width D M The ratio D M / D m The dimension ratio is greater than or equal to 1.1, preferably greater than or equal to 1.8 and / or less than or equal to 4. Such a dimension ratio allows the width of the longitudinal channel 32 to increase sufficiently at the end 322 without excessively increasing the length of the longitudinal channel 32 along the z direction, and keeps the machining of the longitudinal channel 32 simple.

[0128] Specifically, the width D M The range can be between 6mm and 25mm, preferably between 8mm and 20mm.

[0129] It should also be noted that the mixing device according to the invention can be intended to be arranged in a passage 10, which has at least one exchange corrugation downstream of the mixing device, the at least one exchange corrugation comprising exchange channels, each exchange channel having a width ranging from 0.6 mm to 2 mm, preferably at least 0.7 mm and / or at most 1.5 mm.

[0130] Preferably, the minimum width D is measured at the end 324a of the downstream portion 324. m And the maximum width D was measured at the second exit 322. M .

[0131] Advantageously, the longitudinal channel 32 is defined by a lateral wall 325 that forms the outer contour of the channel 32 in a longitudinal cross-sectional plane parallel to the longitudinal direction z and the lateral direction y, the channel having an axis of symmetry AA' parallel to the longitudinal direction z.

[0132] It should be noted that the lateral walls 325 of the passage are preferably erected in a direction orthogonal to the longitudinal direction z and the lateral direction y. Advantageously, the walls 325 have a height measured along the direction x, which is constant across the entire length of the passage 32.

[0133] Alternatively, a variation in the height of wall 325 can be envisioned, particularly increasing the height toward the second outlet 322 (i.e., the downstream portion 324), with the wall depth increasing toward the second outlet 322 until it optionally reaches the height of passage 10 at the second outlet 322. This provides additional freedom to increase the fluid passage cross-section of the downstream portion 324 and thus slows the fluid, allowing it to also be homogenized at the height of passage 10.

[0134] Advantageously, at least a portion of the downstream portion 324 has a curved outer profile, preferably a convex outer profile. Figure 4 An embodiment of a longitudinal channel 32 including such a downstream section 324 is schematically shown. The curved outer profile at the downstream section provides better guidance for the flow of fluid in the downstream section from the mixing device to its outlet, and in particular avoids any separation, fluid recirculation, or turbulence that could be caused by sharp edges on the walls and result in undesirable additional pressure losses of the fluid.

[0135] It is also possible that the entire downstream portion 324, or a portion thereof, has an isosceles trapezoidal external profile as a longitudinal section in a plane parallel to the longitudinal direction z and the lateral direction y, and the lateral walls at this portion are straight walls. Figure 5 An example of the entire downstream section 324 having such an external profile is shown schematically.

[0136] Specifically, by considering the downstream face 326 at the point where the mixing device 3 appears downstream of the downstream portion 324, the outer profile can form an angle θ, which is measured between the tangent T that is tangent to the outer profile at the intersection with the downstream face 326 and the axis of symmetry AA', and the angle ranges between 5° and 85°. These values ​​allow the width of the channel 32 at the second outlet 322 to be sufficiently increased to facilitate better distribution of the two-phase fluid F1 along the direction y across the width of the exchanger without causing an excessively rapid widening that could lead to pressure loss in the fluid F1, nor excessively increasing the length L4 and thus the length of the mixing device 3.

[0137] Figure 9 An embodiment is shown in which the downstream portion is immediately widened in the longitudinal direction z at the end 324a in a particular manner.

[0138] Preferably, the upstream portion 323 is connected to the downstream portion 324 via its end 324a.

[0139] Advantageously, the upstream portion 323 has a length L3 measured along the longitudinal direction z and a ratio L3 / L4, which ranges between 1 and 15, preferably between 3 and 12.

[0140] For example, the length L4 can range from 5mm to 40mm. The length L3 can range from 30mm to 70mm.

[0141] Advantageously, the at least one opening 34 appears in the longitudinal channel 32 at its upstream portion 323, preferably at a distance L from the end 324a of the downstream portion 324. z L z The length L3 of the upstream portion 323 is at least 4%, more preferably between 7% and 90%, and even more preferably between 10% and 50%. Specifically, the opening 34 may appear at a distance L from the end 324a of the downstream portion 324 within a range of 3 mm to 70 mm. z Advantageously, one or more openings 34 of the longitudinal channel 32 appear at its downstream portion 323. The mixing device advantageously does not have openings 34 appearing at its upstream portion 324.

[0142] Therefore, the first phase 61 and the second phase 62 mix sufficiently upstream of the downstream section 324, such that, on the one hand, the two-phase fluid has time to be properly homogenized before entering the downstream section 324, and on the other hand, any recirculation zone of the fluid in the downstream section 324 does not interrupt the flow of the first phase 61 through the opening 34 of the lateral channel 31 to the longitudinal channel 32, an interruption that would lead to poor distribution. The higher velocity of the second phase 62 in the section 323 of the channel 32, compared to the velocity of fluid F1 in section 324, also facilitates the passage of phase 61 from channel 31 to channel 32 via the opening 34, due to the high inertia of phase 62 over phase 61 and the resulting drive.

[0143] Preferably, it should be noted that the position of the at least one opening 34 varies along the longitudinal direction z between the longitudinal channels. In particular, for this reason, some openings 34 may be closer to the end 324a than others.

[0144] Furthermore, it should be noted that, within the scope of this invention, longitudinal channels advantageously possess the same dimensional characteristics, namely, the same external contour, the same depth, the same ratio L3 / L4, and the same distance L. z However, in some configurations, the length ratio of at least one channel to at least one feature of other channels, particularly the downstream and upstream portions, can be changed.

[0145] Preferably, particularly such as Figure 4 As shown, the entire or part of the upstream portion 323 has a straight outer profile with a constant width D3, which is preferably equal to the minimum width D of the downstream portion 324. m According to one possibility, it can be envisioned that the upstream portion 323 has a variable width D3 across its entire or partial length, where D... y It is greater than the maximum value that D3 can achieve.

[0146] Figure 6 and Figure 7 An embodiment is illustrated schematically in which the longitudinal channel 32 includes at least one barrier 327 arranged to subdivide the downstream portion 324 into a plurality of intermediate channels 328 that appear at the second exit 322.

[0147] This prevents the mixture from flowing completely in the longitudinal direction z and forces the flow to widen in the lateral direction y. The creation of the intermediate channel is particularly advantageous when the mass flow rate in the longitudinal channel 32 is relatively high, because in this case the mixture has significant inertia in the longitudinal direction z, that is, the mixture tends to continue flowing in the direction z even when the longitudinal channel widens.

[0148] Installing one or more obstructions allows the flow direction of the two-phase mixture to be altered by providing a y-component to its velocity. Therefore, the angular opening of the fluid jet at the longitudinal channel outlet increases, thereby providing a greater number of exchange channels downstream of the mixing unit.

[0149] Obstacles can also be used to maintain a constant or quasi-constant fluid flow cross-section at the downstream portion, or optionally reduce said cross-section, although it is widening. It should be noted that "fluid flow cross-section" is understood as the surface through which the fluid flows, measured perpendicular to the longitudinal direction z; this is to ensure lateral expansion of the mixture without increasing the fluid flow cross-section.

[0150] Therefore, the pressure loss is rebalanced along the longitudinal channel.

[0151] Preferably, at the second outlet 322, the total surface area of ​​the obstacle 327, measured in a cross-sectional plane perpendicular to the longitudinal direction z, is between 20% and 80%, preferably between 30% and 70%, of the total fluid passage section of the downstream portion 324, measured in the cross-sectional plane.

[0152] In the case of several obstacles, the total surface is understood as the sum of the surfaces of each obstacle.

[0153] Specifically, it can be proposed that the surface of the obstacle, measured at a distance of 1 mm in the longitudinal direction z along the fluid flow direction, after the point of occurrence in channel 32, i.e., at the location called the impact position (1 mm after the point of occurrence of the obstacle where the fluid impacts the obstacle), occupies between 1% and 80% of the fluid passage cross section of channel 32 determined in the cross-sectional plane located at the impact position.

[0154] In a particular embodiment, the longitudinal channel 32 further includes at least one balancing channel 329 fluidly connecting these intermediate channels 328. This allows for the rebalancing of fluid pressure between the intermediate channels 328 in the event of differences in fluid flow rate and pressure between the intermediate channels. Figure 8 An example of such a configuration is shown.

[0155] Advantageously, an even number of intermediate channels are provided to maintain symmetrical distribution of the mixture along axis AA' within the longitudinal channels.

[0156] These one or more obstacles can be manufactured with longitudinal channels by milling, injection molding of metal, electro-etching, or laser processing. Additive manufacturing methods are also conceivable.

[0157] Preferably, the height of the obstacle 327 is equal to the height of the lateral wall of the longitudinal passage.

[0158] Preferably, the at least one barrier 327 has a width dy measured in the lateral direction y, which increases toward the second outlet 322, and preferably has a curved, convex, and / or concave outer profile. This allows the barrier to be shaped to avoid additional pressure loss of fluid F1 in the downstream portion 324 of the channel 32 by separating the fluid at the barrier walls or by a zone for recirculating the fluid.

[0159] Preferably, a number of pathways 10 in the first group, advantageously all pathways 10, include the mixing device according to the invention.

[0160] Preferably, at least one pathway 20 of the second group is arranged between at least one pair of successive pathways 10 of the first group.

[0161] Preferably, the longitudinal channels 32 of the mixing device 3 are spaced apart by a constant distance D. A This constant distance is measured parallel to the longitudinal direction y.

[0162] It should be noted that the position y in the lateral direction of each channel can be determined by considering the position of the center of each channel along the lateral direction y. i y i+1 y i+2 ...For example, by considering channels in the form of parallelepiped grooves, such as... Figure 2 The channels shown are positioned along the y-direction corresponding to the axis of symmetry of the channel, which is equidistant from the side walls of the channel. Figure 2 As shown.

[0163] Distance D A The range can be between 10mm and 40mm, and preferably greater than or equal to 20mm and less than or equal to 30mm.

[0164] To illustrate the homogenization effect obtained using the present invention, Figure 11 The results of simulating the propagation of a two-phase mixture in the longitudinal channel of a conventional mixing device (configuration A) and a mixing device according to an embodiment of the present invention (configuration B) are shown.

[0165] In configuration A, the mixing device is in the form of a grooved rod, which includes a series of parallelepiped grooves spaced 30 mm apart as longitudinal channels. Each groove is 7 mm wide, 70 mm long, and 7 mm high.

[0166] exist Figure 10In configuration B, which is schematically shown in the middle section, the mixing device is in the form of grooved rods with grooves spaced 30 mm apart. Each groove is in the form of a longitudinal channel with an upstream portion 323 that is 7 mm wide, 63 mm long, and 7 mm high. The downstream portion 324 has a truncated cone shape with a width of 7 mm at end 324a and a width of 14 mm at the second outlet 322. The upstream portion 323 is 7 mm long and 7 mm high. An isosceles triangular barrier is placed in the downstream portion 324, symmetrical about the axis of symmetry AA', with a height of 7 mm along the z-direction and a base width of 7 mm at the second outlet 322. Width D M It is twice that of D3. The ratio L3 / L4 is 8, and the length L z The diameter is 5 mm. The angle θ is 45 degrees. It should be noted that configuration B corresponds to the following specific case, in which, due to the presence of the obstruction, the fluid flow through the downstream section remains constant along the longitudinal direction z of the cross section, but the width of said section increases toward the second outlet 322.

[0167] Based on the same figures, the longitudinal channels of the mixing devices in configurations A and B are arranged at the same positions along the lateral direction y. i y i+1 ...place.

[0168] In configurations A and B, a "sawtooth" type corrugation 11 (i.e., partially offset corrugations) is arranged at the outlet of the mixing device in each passage. These corrugations are "1 / 8" sawtooth type (1" = 1 inch = 25.4 mm) (i.e., the sawtooth length is 25.4 / 8 = 3.18 mm) and have a density of 23 fins per inch (1 inch = 25.4 mm) measured in the lateral direction y.

[0169] Simulation is a type of calculation using the finite element method to perform three-dimensional CFD (computational fluid dynamics) calculations.

[0170] Figure 11 This diagram shows several distance values ​​between outlet 322 and a plane parallel to directions x and y, and the minimum dimensionless fluid velocity value (denoted as V) measured in the longitudinal direction z at successive cross sections of the corrugation located after outlet 322 within said plane. z The evolution of the ripples. These velocity values ​​represent the quality of fluid distribution within the ripples: negative values ​​indicate the presence of a recirculation zone where the fluid stagnates at its center. Zero values ​​indicate the presence of stagnant fluid. Since the stagnant fluid is not renewed, it does not participate in heat exchange and reduces the overall efficiency of the exchanger.

[0171] The fluid distribution performance index is the minimum necessary distance along the longitudinal direction z that allows all fluids to have a positive velocity along the longitudinal direction z.

[0172] As can be seen, the minimum necessary distance is reduced from 45 mm to 31 mm, that is, configuration B according to the invention is reduced by 35% compared to conventional configuration A. With the help of the invention, the homogenization of the two-phase mixture distributed by the mixing device is significantly improved, and the efficiency of the exchanger is improved.

[0173] Figure 12 and Figure 13 An example of implementing one or more switches according to the present invention is shown.

[0174] Figure 12 A method for liquefying a hydrocarbon stream 102, which is a second fluid F2, is schematically shown. The hydrocarbon stream may be natural gas, which may be pretreated before being introduced into the heat exchanger 1, for example, by separating at least one of the following components: water, carbon dioxide, sulfur compounds, methanol, and mercury.

[0175] Preferably, the hydrocarbon stream contains at least 60%, preferably at least 80%, of methane in mole fraction.

[0176] Hydrocarbon stream 102 and cooling stream 202 enter exchanger 1 via third inlet 25 and fourth inlet 21, respectively, to circulate in dedicated passages within the exchanger in a direction parallel to the longitudinal direction z, which is substantially vertical during operation. Hydrocarbon stream 102 circulates through a second set of passages 20 supplied by the third inlet 25. Cooling stream 202 circulates through a third set of passages arranged within the stack body forming exchanger 1. These streams exit via a third outlet 22 and a first outlet 23. The second and third sets of passages are arranged alternately, wholly or partially, and / or adjacent to all or part of the first set of passages 10.

[0177] Advantageously, the fourth inlet 21 for the cooling flow 202 and the third inlet 25 for the hydrocarbon flow 102 are arranged such that the cooling flow 202 and optionally the hydrocarbon flow 102 flow downward in the same direction toward the second end 1b of the exchanger, which is located at a lower level 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 in the exchanger's temperature range. Depending on the associated method, this inlet point can be either the fourth inlet 21 or the third inlet 25.

[0178] Hydrocarbon stream 102 can be introduced into exchanger 1 in a temperature range between -130°C and 40°C.

[0179] According to one possibility, the hydrocarbon stream 102 is introduced into the exchanger 1 in a completely gaseous or partially liquefied state within a temperature range between -80°C and -35°C.

[0180] According to another possibility, hydrocarbon stream 102 is introduced into exchanger 1 in a fully liquefied state within a temperature range of -130°C to -100°C.

[0181] The cooling flow 201 exiting the exchanger 1 expands through an expansion member T3 (such as a turbine, valve, or a combination of turbine and valve) to form a two-phase cooling flow 203 comprising a first phase and a second phase. The two-phase cooling flow 203 forms the previously considered first fluid F1. At least a portion of the expanded two-phase cooling flow 203 is introduced into a separator member 27. The separator member can be any device suitable for separating the two-phase fluid into a predominantly gaseous flow on one hand and a predominantly liquid flow on the other.

[0182] The second phase 62 is introduced via manifold 52, which supplies the mixing device 3 with its second inlet 321 arranged in the first set of passages 10. The first phase 61 is introduced via a first manifold 30, which supplies the mixing device 3 with its first inlet 321 arranged in each passage 10. Figure 9 The first entry 311 (not shown in the image).

[0183] Preferably, the second phase is introduced via an inlet (i.e., an inlet point in the exchanger) located in a region of the second end 1b corresponding to the cold end of the exchanger 1, at which the fluid is introduced at the lowest temperature in the fluid temperature range of the exchanger.

[0184] The two phases 61 and 62 of the two-phase flow 203 are recombine within the exchanger 1 and are distributed in the passage 10 of the exchanger 1 as a liquid-gas mixture, each passage being provided with a mixing device 3 according to the invention.

[0185] Preferably, the two-phase cooling flow 203 is introduced into the heat exchanger 1 at a first temperature T1 ranging from -120°C to -160°C, and exits the heat exchanger 1 at a second temperature T2 higher than the first temperature T1, preferably ranging from -35°C to -130°C.

[0186] According to another possibility, the two-phase cooling flow 203 is introduced into the heat exchanger 1 at a first temperature T1 ranging from -130°C to -80°C, and exits the heat exchanger 1 at a second temperature T2 higher than the first temperature T1, preferably ranging from -10°C to 50°C.

[0187] At least a portion of the two-phase cooling flow 203 flows upward through passage 10 and is vaporized by counter-current cooling of the natural gas 102 and the cooling flow 202. Thus, a cooled and / or at least partially liquefied hydrocarbon flow 101 is obtained at the outlet of exchanger 1.

[0188] The vaporized cooling flow leaves the heat exchanger 1 via a second outlet 42 connected to manifold 55 so that it can be compressed by the compressor and then exchange heat with an external cooling fluid, such as water or air, in an indirect heat exchanger. Figure 12 (26 locations in the compressor) are cooled. The cooling flow pressure at the compressor outlet can range from 2 MPa to 9 MPa. The cooling flow temperature at the outlet of the indirect heat exchanger can range from 10°C to 45°C.

[0189] exist Figure 12 In the method described, the cooling flow is not divided into separate parts. However, in order to optimize the path in the exchanger 1, the cooling flow can also be divided into two or three parts, each of which expands at a different pressure level and is then sent to different stages of the compressor.

[0190] Preferably, the cooling stream 202 contains a hydrocarbon having at most 5 carbon atoms, preferably at most 3, and more preferably at most 2 carbon atoms.

[0191] Preferably, the cooling stream 202 is formed, for example, from 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.

[0192] The mole fraction (%) of the components in the cooling stream can be:

[0193] - Nitrogen: 0% to 10%;

[0194] -Methane: 20% to 70%;

[0195] - Ethane: 30% to 70%;

[0196] - Ethylene: 20% to 70%

[0197] -Propane: 0% to 20%;

[0198] - n-Butane: 0% to 30%;

[0199] -Isopentane: 0% to 20%.

[0200] Optionally, the cooling stream may include ethylene as a substitute for ethane, and C4 and C5 compounds as substitutes for all or part of propane.

[0201] Preferably, the natural gas leaves the exchanger 1 at least partially liquefied at a temperature and a pressure equal to the inlet pressure of the natural gas (to achieve the closest possible pressure loss), preferably at a temperature at least 10°C higher than the bubble point temperature of the liquefied natural gas produced at atmospheric pressure (the bubble point temperature represents the temperature at which the first vapor bubble forms in liquid natural gas at a given pressure). For example, the natural gas leaves the exchanger 1 at a temperature in the range of -100°C to -162°C and a pressure in the range of 2 MPa to 7 MPa. Under these temperature and pressure conditions, depending on its composition, the natural gas typically does not remain liquid after expanding to atmospheric pressure.

[0202] Advantageously, the method for liquefying hydrocarbon streams according to the invention can be implemented in one or more additional refrigeration cycles upstream of the main refrigeration cycle described above, in order to pre-cool the hydrocarbon streams.

[0203] Figure 13 A method for liquefying hydrocarbon streams, such as natural gas, is schematically illustrated. This method includes an additional refrigeration cycle in which the natural gas is cooled to near its dew point using at least two different expansion levels to improve cycle efficiency. This additional refrigeration cycle is implemented via an additional cooling flow 300 in an additional heat exchanger 2, referred to as a precooling exchanger, which is arranged upstream of heat exchanger 1 in the flow direction of the hydrocarbon stream 110, and forms a liquefaction exchanger.

[0204] In this embodiment, the supply stream 110 arrives at a pressure, for example, between 2.5 MPa and 7 MPa, and a temperature, between 20°C and 60°C. When the supply stream 110 comprises a hydrocarbon mixture, such as natural gas, a cooling stream 202 and an additional cooling stream 300 enter an additional exchanger 2 to circulate therein in a downward direction along a parallel direction and in the same direction.

[0205] 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, for example, within a temperature range of -35°C to -70°C. The cooling stream 202 can also exit the exchanger 2 completely condensed, for example, within a temperature range of -35°C to -70°C. Stream 102 is then introduced into the exchanger 1.

[0206] from Figure 13 As can be seen, stream 203 vaporizes in exchanger 1 and leaves the exchanger to be compressed by compressor K2, and is then cooled in indirect heat exchanger C2 by exchanging heat with an external cooling fluid such as water or air. The cooling stream originating from exchanger C2 then returns to auxiliary exchanger 2.

[0207] The additional cooling stream 300 can be formed from a mixture of hydrocarbons (such as a mixture of ethane and propane), but may also contain methane, ethylene, propylene, butane, and / or pentane. The molar fraction (%) of the components in the first coolant mixture can be:

[0208] - Ethane: 30% to 70%;

[0209] -Propane: 30% to 70%;

[0210] -Butane: 0% to 20%;

[0211] In the additional exchanger 2, which is also a brazed plate fin type, at least two streams originating from the additional cooling flow 300 are drawn from the exchanger at at least two different outlet points and then expand to different pressure levels, generating partial two-phase expansion flows, each comprising a first phase and a second phase. At least a portion of these partial two-phase flows is introduced into corresponding separator components 24, 25, and 26.

[0212] exist Figure 13 In the embodiment, three portions of the additional cooling flow 300 in the first phase are successively extracted, also referred to as partial flow rates or flows 301, 302, and 303.

[0213] The gas and liquid phases separated by each separator component are introduced via separate inlets of the auxiliary heat exchanger 2 and recombine within a mixing unit (not shown) to form at least two coolant fluids introduced into a dedicated coolant passage in a liquid-gas mixture state. Alternatively, only the first phase is injected into the exchanger 2, and the gas phase is directed to the inlet of the compression stage of the compressor K1. These coolants are vaporized in the auxiliary exchanger 2 through heat exchange with the supply stream 110, the cooling stream 202, and the auxiliary cooling stream 300.

[0214] Advantageously, at least two types of mixing devices 2 (such as those that can be arranged within the exchanger 1 according to the invention) are arranged in the additional exchanger. Thus, the additional exchanger includes at least two coolant passages, each coolant passage including a mixing device, which includes one or more features previously described for the first mixing device 3A and the second mixing device 3B.

[0215] The vaporized coolant is sent to different stages of compressor K1 for compression in its respective coolant passages, and then condenses in the condenser through heat exchange with an external cooling fluid (e.g., water or air). The stream originating from the condenser returns to the auxiliary heat exchanger 2. The pressure range of the first cooling stream at the outlet of compressor K1 can be between 2 MPa and 6 MPa. The temperature range of the auxiliary cooling stream at the outlet of condenser C1 can be between 10°C and 45°C.

[0216] Preferably, the coolant flows upward along the longitudinal direction z from one end 2b of the auxiliary exchanger 2 to the other end 2a. End 2b corresponds to the cold end of the auxiliary exchanger 2, where the coolant is introduced at the lowest temperature in the auxiliary exchanger 2.

[0217] Of course, the present invention is not limited to the specific examples described and shown in this application. Other alternative embodiments, within the capabilities of those skilled in the art, are conceivable without departing from the scope of the invention. For example, depending on the constraints imposed by the method to be implemented, other configurations for injecting / extracting fluid from the exchanger, other flow paths and directions of the fluid, other types of fluid, mixing devices, and other forms of lateral and longitudinal channels are obviously conceivable.

Claims

1. A mixing device (3) for distributing a mixture of a first phase (61) and a second phase (62) of a first fluid (F1) generally in a longitudinal direction (z) in at least one passage (10) of a heat exchanger (1), said mixing device (3) comprising: - At least one lateral channel (31) configured for the first phase (61) to flow from at least one first inlet (311); - A series of longitudinal channels (32) extending along the longitudinal direction (z), and each longitudinal channel is configured for the second phase (62) to flow from the second inlet (321) to the second outlet (322), the longitudinal channels being sequential to each other along a lateral direction (y) orthogonal to the longitudinal direction (z); as well as - At least one opening (34) fluidly connects the lateral channel (31) to at least one longitudinal channel (32), such that the mixing device (3) is configured to dispense a mixture of the first phase (61) and the second phase (62) via a second outlet (322) of the longitudinal channel (32), wherein the at least one longitudinal channel (32) of the mixing device (3) is divided into an upstream portion (323) and a downstream portion (324) along the longitudinal direction (z), the upstream portion and the downstream portion each having a length (L3, L4) measured along the longitudinal direction (z) and a width (D3, D4) measured along the lateral direction (y). y The downstream portion (324) is arranged between the upstream portion (323) and the second outlet (322), and the width (D) of the downstream portion (324) at any point along its length (L4) is... y The width (D3) of the upstream portion (323) is greater than that of the downstream portion (324), and the downstream portion (324) appears at the downstream surface (326) of the mixing device (3), and the second outlet (322) is located at the downstream surface (326). The downstream portion (324) is characterized by having an outer profile in a longitudinal section in a plane (P) parallel to the longitudinal direction (z) and the lateral direction (y), the outer profile forming an angle (θ), which is measured between a tangent (T) that is tangent to the outer profile at the intersection with the downstream surface (326) and the axis of symmetry (AA'), the angle being between 5° and 85°.

2. The apparatus as claimed in claim 1, characterized in that, The downstream section (324) has a width (D) that increases continuously along its entire length (L4) toward the second outlet (322). y ).

3. The apparatus as described in claim 1, characterized in that, In a plane (P) parallel to the longitudinal direction (z) and the lateral direction (y), the downstream portion (324) has an overall or partial external profile in the form of an isosceles trapezoid as a longitudinal section.

4. The apparatus as claimed in claim 2, characterized in that, In a plane (P) parallel to the longitudinal direction (z) and the lateral direction (y), the downstream portion (324) has an overall or partial external profile in the form of an isosceles trapezoid as a longitudinal section.

5. The apparatus as claimed in claim 1, characterized in that, The upstream portion (323) of the longitudinal channel (32) is connected to the downstream portion via an end (324a), and the at least one opening (34) is located at the upstream portion (323) at a distance (L) from the end (324a). z It appears in the longitudinal channel (32) at position ).

6. The apparatus as claimed in claim 2, characterized in that, The upstream portion (323) of the longitudinal channel (32) is connected to the downstream portion via an end (324a), and the at least one opening (34) is located at the upstream portion (323) at a distance (L) from the end (324a). z It appears in the longitudinal channel (32) at position ).

7. The apparatus as claimed in claim 3, characterized in that, The upstream portion (323) of the longitudinal channel (32) is connected to the downstream portion via an end (324a), and the at least one opening (34) is located at the upstream portion (323) at a distance (L) from the end (324a). z It appears in the longitudinal channel (32) at position ).

8. The apparatus as claimed in claim 4, characterized in that, The upstream portion (323) of the longitudinal channel (32) is connected to the downstream portion via an end (324a), and the at least one opening (34) is located at the upstream portion (323) at a distance (L) from the end (324a). z It appears in the longitudinal channel (32) at position ).

9. The apparatus as claimed in claim 5, characterized in that, The distance (L) z It is greater than or equal to 4% of the length (L3) of the upstream portion (323).

10. The apparatus as claimed in claim 9, characterized in that, The distance (L) z ) within 7% to 90% of the length of the upstream portion (323).

11. The apparatus according to any one of claims 1-10, characterized in that, The at least one opening (34) is arranged such that when the first phase (61) flows from the first inlet of the lateral channel (31) and the second phase (62) flows from the second inlet (321) of the longitudinal channel (32), the mixing of the first phase (61) and the second phase (62) occurs upstream of the downstream portion (324).

12. The apparatus according to any one of claims 1-10, characterized in that, The one or more openings (34) of the mixing device (3) appear at the upstream portion (323) of the longitudinal channel (32).

13. The apparatus as claimed in claim 11, characterized in that, The one or more openings (34) of the mixing device (3) appear at the upstream portion (323) of the longitudinal channel (32).

14. The apparatus according to any one of claims 1-10, characterized in that, Each of the series of longitudinal channels (32) includes at least one opening (34) that appears in its upstream portion (323), the position of which at least one opening (34) varies between these longitudinal channels (32) along the longitudinal direction (z).

15. The apparatus as claimed in claim 11, characterized in that, Each of the series of longitudinal channels (32) includes at least one opening (34) that appears in its upstream portion (323), the position of which at least one opening (34) varies between these longitudinal channels (32) along the longitudinal direction (z).

16. The apparatus as claimed in claim 12, characterized in that, Each of the series of longitudinal channels (32) includes at least one opening (34) that appears in its upstream portion (323), the position of which at least one opening (34) varies between these longitudinal channels (32) along the longitudinal direction (z).

17. The apparatus according to any one of claims 1-10, characterized in that, The lengths (L3) of the upstream portion (323) and (L4) of the downstream portion (324) are such that their ratio is between 1 and 15.

18. The apparatus as claimed in claim 11, characterized in that, The lengths (L3) of the upstream portion (323) and (L4) of the downstream portion (324) are such that their ratio is between 1 and 15.

19. The apparatus as claimed in claim 12, characterized in that, The lengths (L3) of the upstream portion (323) and (L4) of the downstream portion (324) are such that their ratio is between 1 and 15.

20. The apparatus as claimed in claim 14, characterized in that, The lengths (L3) of the upstream portion (323) and (L4) of the downstream portion (324) are such that their ratio is between 1 and 15.

21. The apparatus as claimed in claim 17, characterized in that, The ratio is in the range of 3 to 12.

22. The apparatus according to any one of claims 1-10, characterized in that, The downstream portion (324) has a depth measured in a direction called the stacking direction (x), which increases toward the second outlet (322), perpendicular to the longitudinal direction (z) and the lateral direction (y).

23. The apparatus as claimed in claim 11, characterized in that, The downstream portion (324) has a depth measured in a direction called the stacking direction (x), which increases toward the second outlet (322), perpendicular to the longitudinal direction (z) and the lateral direction (y).

24. The apparatus as claimed in claim 12, characterized in that, The downstream portion (324) has a depth measured in a direction called the stacking direction (x), which increases toward the second outlet (322), perpendicular to the longitudinal direction (z) and the lateral direction (y).

25. The apparatus as claimed in claim 14, characterized in that, The downstream portion (324) has a depth measured in a direction called the stacking direction (x), which increases toward the second outlet (322), perpendicular to the longitudinal direction (z) and the lateral direction (y).

26. The apparatus as claimed in claim 17, characterized in that, The downstream portion (324) has a depth measured in a direction called the stacking direction (x), which increases toward the second outlet (322), perpendicular to the longitudinal direction (z) and the lateral direction (y).

27. The apparatus as claimed in claim 21, characterized in that, The downstream portion (324) has a depth measured in a direction called the stacking direction (x), which increases toward the second outlet (322), perpendicular to the longitudinal direction (z) and the lateral direction (y).

28. The apparatus as claimed in any one of claims 1-10, characterized in that, The longitudinal passage (32) includes at least one obstacle (327) arranged to subdivide the downstream section (324) into a plurality of intermediate passages (328) that appear at the second exit (322).

29. The apparatus as claimed in claim 11, characterized in that, The longitudinal passage (32) includes at least one obstacle (327) arranged to subdivide the downstream section (324) into a plurality of intermediate passages (328) that appear at the second exit (322).

30. The apparatus as claimed in claim 12, characterized in that, The longitudinal passage (32) includes at least one obstacle (327) arranged to subdivide the downstream section (324) into a plurality of intermediate passages (328) that appear at the second exit (322).

31. The apparatus as claimed in claim 14, characterized in that, The longitudinal passage (32) includes at least one obstacle (327) arranged to subdivide the downstream section (324) into a plurality of intermediate passages (328) that appear at the second exit (322).

32. The apparatus as claimed in claim 17, characterized in that, The longitudinal passage (32) includes at least one obstacle (327) arranged to subdivide the downstream section (324) into a plurality of intermediate passages (328) that appear at the second exit (322).

33. The apparatus as claimed in claim 21, characterized in that, The longitudinal passage (32) includes at least one obstacle (327) arranged to subdivide the downstream section (324) into a plurality of intermediate passages (328) that appear at the second exit (322).

34. The apparatus as claimed in claim 22, characterized in that, The longitudinal passage (32) includes at least one obstacle (327) arranged to subdivide the downstream section (324) into a plurality of intermediate passages (328) that appear at the second exit (322).

35. The apparatus as claimed in claim 28, characterized in that, The intermediate channel (328) is arranged symmetrically with respect to the axis of symmetry (AA') of the longitudinal channel (32).

36. A heat exchange device, comprising: - A heat exchanger (1) comprising a plurality of plates (2) arranged parallel to each other and parallel to a longitudinal direction (z), the plates (2) being stacked in a spaced-out manner to define together at least one first set of passages and at least one second set of passages, the first set of passages being configured for a first fluid (F1) to flow generally along the longitudinal direction (z), and the second set of passages being configured for a second fluid (F2) to flow in order to form a heat exchange relationship with the first fluid (F1); - The source of the first phase (61) of the first fluid (F1), which is fluidly connected to at least one first manifold (30) of the heat exchanger (1); - The source of the second phase (62) of the first fluid (F1), which is fluidly connected to at least one second manifold (52) of the heat exchanger (1); - The mixing device (3) according to any one of claims 1 to 35, the mixing device (3) is arranged in at least one passage (10) of a first series and is configured to dispense the first fluid (F1) formed by the mixture of the first phase (61) and the second phase (62) in the passage (10) of the first series, the first inlet (311) of the lateral passage (31) being in fluid communication with the first manifold (30) and the second inlet (321) being in fluid communication with the second manifold (52), the first phase (61) being a liquid phase and the second phase (62) being a gas phase.

37. A method for mixing a first phase (61) and a second phase (62) of a first fluid (F1) in a mixing apparatus (3) as claimed in any one of claims 1 to 35, the method comprising the steps of: i) The first phase (61) of the first fluid (F1) is introduced through at least one first inlet (311) of the lateral channel (31); ii) The second phase (62) of the first fluid (F1) is introduced via the second inlet (321) of each longitudinal channel (32), and the second phase (62) flows in the longitudinal direction (z) of each longitudinal channel (32) to the second outlet (322) of the longitudinal channel (32); iii) At least a portion of the first phase (61) is allowed to flow through the opening (34) from the lateral channel (31) toward the longitudinal channel (32) so as to mix the first phase (61) with the second phase (62) in the longitudinal channel (32); iv) Distribute the mixture of the first phase (61) and the second phase (62) via the second outlet (322) of each longitudinal channel (32).

38. The mixing method as described in claim 37, characterized in that, The first phase (61) mixes with the second phase (62) upstream of the downstream portion (324).

39. A method for liquefying a hydrocarbon stream (102) as a second fluid (F2) by heat exchange with at least one two-phase cooling stream (203) as a first fluid (F1), said method implementing the mixing method as described in claim 37 or 38, and comprising the following steps: a) Introduce the hydrocarbon stream (102) into the second set of passages of the heat exchanger (1); b) Introduce the cooling flow (202) into the third set of passages of the heat exchanger (1); c) Discharge the cooling flow (201) from the heat exchanger (1) and expand the cooling flow (201) to at least one pressure level to generate at least one two-phase cooling flow (203); d) Separate at least a portion of the two-phase cooling flow (203) originating from step c) into a second phase (62) and a first phase (61); e) A mixing device (3) is arranged in at least one passage (10) of the first set of passages of the heat exchanger (1); f) Introduce at least a portion of the second phase (62) and at least a portion of the first phase (61) into the mixing device (3) to obtain a first fluid (F1) formed by the mixture of the first phase (61) and the second phase (62) at the outlet of the mixing device (3); g) By exchanging heat with at least the hydrocarbon stream (102), at least a portion of the first fluid (F1) originating from step f) is vaporized in the passage (10), thereby obtaining a cooled and / or at least partially liquefied hydrocarbon stream (101) at the outlet of the exchanger (1).

40. The mixing method as described in claim 39, characterized in that, The hydrocarbon stream (102) is natural gas.

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