Heat exchanger with improved corrosion resistance

Abstract

The invention relates to a heat exchanger comprising a plurality of plates (2) arranged so as to define between them at least one set of first passes (3) and a set of second passes (4), at least one first pass (3) having a height H defined as the distance, measured orthogonally to the plates (2), between the two adjacent plates (2) defining said first pass (3), and comprising a succession of intercalated partitions (11) arranged so as to define a plurality of channels (12), said intercalated partitions (11) succeeding one another, in a lateral direction (x) orthogonal to the longitudinal direction (z) and parallel to the plates (2), at intervals d each defined as the distance, measured parallel to the lateral direction (x) and at mid-height of said first pass (3), between two successive intercalated partitions (11), the exchanger being characterized in that the ratio d / H is greater than or equal to 0.8. Figure for the abstract: 2.

Description

Title of the invention: Heat exchanger with improved corrosion resistance

[0001] The present invention relates to a brazed plate type heat exchanger with improved corrosion resistance.

[0002] The present invention applies in particular to a heat exchanger in which at least one of the fluids circulating in the exchanger comprises water, in particular water in liquid or gaseous state.

[0003] The present invention finds particular application in the field of carbon dioxide separation and liquefaction. The present invention can be applied to a heat exchanger that cools or liquefies, in whole or in part, a flow of carbon dioxide, in particular carbon dioxide in the supercritical state, by exchanging heat with a refrigerant such as liquid water.

[0004] The present invention can also find application in the field of syngas separation and cooling. In particular, the invention can be applied to a heat exchanger in which a syngas stream, particularly in a gaseous state containing water vapor, is cooled, or even liquefied in whole or in part, by heat exchange with at least one other syngas stream.

[0005] One technology used is that of brazed aluminum plate and fin or wave heat exchangers, which make it possible to obtain very compact devices offering a large exchange surface area. These exchangers comprise a plurality of plates stacked parallel and spaced so as to define passages between them for the different fluids to be exchanged. Heat exchange structures, generally corrugated structures or waves formed by a succession of fins or wave legs, are inserted between the plates, delimiting channels in the passages through which the fluids flow and forming additional heat exchange surfaces.

[0006] Processes in which supercritical carbon dioxide is cooled against water are known. The heat exchangers used for this type of application are generally shell-and-tube heat exchangers made of stainless steel, particularly duplex stainless steel. These materials offer better resistance to corrosion induced by the cooling water.

[0007] However, tubular heat exchangers are not entirely satisfactory. Indeed, these exchangers operate under relatively high temperature differences, the temperature difference between the heat and refrigerant fluids typically being at best 5°C, and with higher pressure drops than plate heat exchangers, which makes them less While energy-efficient, shell-and-tube heat exchangers are also bulkier and only allow the circulation of two fluids, which may be insufficient in some processes. Furthermore, these primary-surface heat exchangers offer limited flexibility in varying the heat transfer area to suit the characteristics of the fluids involved. Finally, the need to weld the tubes to a retaining plate within the shell can lead to a complex and time-consuming manufacturing process.

[0008] Brazed plate heat exchangers using demineralized water as a cooling fluid for a carbon dioxide stream are also known. The demineralized water circulates in a closed loop, and its pH is monitored to reduce the risk of corrosion in the primary exchanger. The demineralized water is cooled by heat exchange with cooling water in a separate exchanger. However, it is recommended to use chemical absorbents and corrosion inhibitors in the water circuit. Furthermore, since the cooling system includes an additional water circuit, a typical 2°C approach to the primary exchanger is compounded by a 3°C approach to the other exchanger, resulting in the same total approach of typically 5°C achieved with a shell-and-tube heat exchanger.

[0009] Aluminum exhibits relatively good corrosion resistance under atmospheric conditions due to the presence of a protective natural layer of aluminum oxide. However, aluminum corrosion becomes a critical phenomenon in heat exchangers exposed to untreated industrial-grade water. Corrosion is also problematic in the case of wet syngas cooling exchangers against one or more syngas refrigerant streams, as water condenses during heat exchange and, in the presence of carbon dioxide and carbon monoxide, forms acidic condensates. The service life of the exchangers is thus significantly affected by corrosion.

[0010] The use of stainless steel instead of aluminum can be considered to produce plate heat exchangers with improved corrosion resistance. However, due to the lower thermal conductivity of stainless steel compared to aluminum and its higher density, the bodies of these exchangers are smaller and heavier than aluminum plate heat exchangers. They are therefore less suitable for large-scale processes requiring the operation of several exchanger bodies in parallel.

[0011] It is also possible to consider applying a surface treatment to the plates and / or heat exchange structures of the exchangers in order to improve their resistance to the corrosion, for example by anodizing. However, carrying out such treatments can be difficult and ineffective in certain areas of the exchanger, particularly in certain areas of the heat exchange structures which are not easily accessible, leading to inhomogeneities, or even absences, of treatment in these areas.

[0012] The present invention aims to solve, in whole or in part, the problems mentioned above, in particular to propose a brazed plate type heat exchanger offering better corrosion resistance.

[0013] The solution according to the invention is then a plate heat exchanger configured to connect at least a first fluid and a second fluid for heat exchange, said exchanger comprising a plurality of plates arranged parallel to each other and in a longitudinal direction so as to define between them at least one set of first passages for the flow of the first fluid and a set of second passages for the flow of the second fluid, at least one first passage having a height H defined as the distance, measured orthogonally to the plates, between the two adjacent plates defining said first passage, said at least one first passage comprising a succession of intercalated partitions arranged so as to define within the first passage a plurality of channels for the flow of the first fluid parallel to the longitudinal direction, said intercalated partitions succeeding one another,along a lateral direction which is orthogonal to the longitudinal direction and parallel to the plates, at intervals d each defined as the distance, measured parallel to the lateral direction and at mid-height of said first passage, between two successive intermediate partitions, the exchanger being characterized in that the ratio d / H is greater than or equal to 0.8.

[0014] Depending on the case, the exchanger according to the invention may include one or more of the technical characteristics given below.

[0015] The d / H ratio is greater than or equal to 1 and / or less than or equal to 8, in particular less than or equal to 6.

[0016] The intercalated partitions follow one another at intervals d of at least 5 mm, preferably ranging from 6 to 35 mm, more preferably from 10 to 25 mm.

[0017] The intercalated partitions have a partition width Ll, measured parallel to the lateral direction and at mid-height of said first passage, such that the ratio Ll / H is greater than or equal to 0.5, preferably between 0.8 and 3, preferably greater than or equal to 1 and / or less than or equal to 2.

[0018] The intermediate partitions have a partition width Ll of at least 4 mm, preferably at least 5 mm, preferably even more than 15 mm, in particular between 8 and 12 mm.

[0019] Said at least a first passage is delimited at least partially by a pair of sealing bars extending, in the direction of their length, parallel to the longitudinal direction, the intermediate partitions being arranged between the pair of sealing bars.

[0020] Said first passage comprises at least 3 intermediate partitions, preferably at least 8 intermediate partitions, in particular from 10 to 50 intermediate partitions.

[0021] All or part of the channels delimited between the intercalated partitions each define a free volume for the flow of the first fluid.

[0022] The plates defining said at least one first pass have a thickness e, measured orthogonally to the plates (2), such that the ratio e / H is at least equal to 0.4, preferably at least equal to 0.5, preferably even more at most equal to 1, in particular between 0.5 and 0.8.

[0023] At least one intercalary partition is formed by at least one solid bar of overall parallelepiped shape.

[0024] At least one intercalated partition has a top face extending opposite one of the two adjacent plates defining said first passage, a bottom face extending opposite the other of the two adjacent plates defining said first passage and a pair of lateral faces connecting said top and bottom faces, each lateral face being oriented towards an adjacent channel and having, in cross-section in a plane parallel to the lateral direction and orthogonal to the plates, a profile of concave shape towards said adjacent channel, in particular of concave shape with a radius of curvature r such that the ratio r / H is between 0.1 and 2, preferably between 0.2 and 0.5.

[0025] The surfaces of the interlayer partitions and / or the plates delimiting the channels are coated in whole or in part with at least one layer of anti-corrosion coating, in particular with at least one layer resulting from a surface treatment by anodizing or a surface treatment by chemical conversion.

[0026] At least one second passage comprises at least one corrugated heat exchange structure comprising a succession of wave crests and wave bases arranged against the plates and connected alternately by fins, said fins following one another along a corrugation direction of the heat exchange structure which is in particular parallel to the lateral direction.

[0027] The exchanger comprises an alternation of second passages equipped with corrugated exchange structures and first passages equipped with intercalated partitions.

[0028] According to another aspect, the invention relates to the use of a heat exchanger according to the invention in which carbon dioxide as a second fluid, in particular carbon dioxide in the supercritical state, is cooled or at least partially liquefied by heat exchange with the first fluid, the first fluid being preferably water, so as to produce at the outlet of the exchanger a stream of cooled or liquefied carbon dioxide.

[0029] The invention also relates to the use of an exchanger according to the invention in which a first syngas stream as a first fluid is cooled by heat exchange with at least a second syngas stream as a second fluid, so as to produce at the outlet of the cooled syngas exchanger, the first syngas stream comprising hydrogen, carbon monoxide and water and the second syngas stream comprising hydrogen, carbon monoxide and optionally water in a lower content than the water content of the first syngas stream.

[0030] Furthermore, the invention relates to a method for manufacturing a heat exchanger according to the invention, said method comprising the following steps: - a) stacking the plurality of plates parallel to each other and in a longitudinal direction so as to define between them said at least one set of first passages for the flow of the first fluid and said at least one set of second passages for the flow of the second fluid, - b) arrange said succession of intercalated partitions in at least a first pass so as to define within the first pass the plurality of channels for the flow of the first fluid, - c) braze the stack of plates, including the two adjacent plates defining the first passage and the intermediate partitions, - d) after step c), coat all or part of the surfaces of the interlayer partitions and / or the adjacent plates delimiting the channels with an anti-corrosion coating, in particular with at least one layer obtained by anodizing and / or at least one layer obtained by chemical conversion.

[0031] The present invention will now be better understood from the following description, given solely by way of non-limiting example and made with reference to the figures mentioned below.

[0032] [Fig-1] is a three-dimensional view of a heat exchanger according to an embodiment of the invention.

[0033] [Fig.2] is a cross-sectional view of exchanger passages according to an embodiment of the invention.

[0034] [Fig.3] is a partial three-dimensional view of an exchanger passage according to an embodiment of the invention.

[0035] [Fig.4] is a cross-sectional view of an exchanger passage according to an embodiment of the invention.

[0036] [Fig.5] is a cross-sectional view of a heat exchanger plate according to an embodiment of the invention.

[0037] [Fig.6] is a schematic view illustrating a heat exchange system comprising several exchangers according to the invention.

[0038] As can be seen on [Fig. 1], a heat exchanger according to the invention comprises a set of plates 2 arranged parallel to each other with spacing and thus forming a set of first passages 3 and second passages 4 of parallelepiped and flat shape for the flow of at least one first fluid and at least one second fluid to be put into indirect heat exchange via the plates 2.

[0039] The plates 2 and the passages 3, 4 are stacked parallel to each other and along a stacking direction y. In the illustrated case, they extend in two dimensions, length and width, respectively along the longitudinal direction z and the lateral direction x which is orthogonal to the longitudinal direction z and parallel to the plates 2. The plates 2 thus define a plurality of passages 3, 4 for the flow of fluids globally parallel to the longitudinal direction z.

[0040] Over most of their height, all or part of the passages contain heat exchange structures, which may include, in particular, corrugated sheets 8, also called heat exchange waves. These structures may or may not be perforated. These heat exchange structures are preferably of the vertical generator type, or so-called "easyway" arrangement. In this case, the corrugated heat exchange structures, in operation, have an overall corrugation direction that is orthogonal to the longitudinal direction z and parallel to the lateral direction x. The heat exchange structures are brazed to the plates 2. The heat exchange structures enhance the heat exchange between the fluids flowing on either side of the plates 2.

[0041] It is also conceivable that the heat exchange structures of the exchanger may have different directions, dimensions and / or undulation shapes than those of the embodiments described in this application.

[0042] At the ends of the passages, the heat exchange structures 8 can be extended by distribution waves to distribute the fluids into the respective passages. Passages of the heat exchanger 1 can be provided with at least one heat exchange structure 8. Along their edges, the passages 3 can be closed by sealing bars 6. The plates 2 are spaced apart by these sealing bars 6, which do not completely close the passages 3 but leave inlet and outlet openings. The inlets and outlets of each passage, each carrying the same fluid, are connected by manifolds 7, 9 equipped with tubes 10 for the introduction and discharge of the fluid.

[0043] With reference to the embodiment illustrated in [Fig. 2], at least one first passage 3 of a heat exchanger according to the invention comprises, as a heat exchange structure, a succession of intercalated partitions 11 arranged so as to delimit, within said first passage 3, channels 12 for the flow of the first fluid. Said at least one first passage 3 has a height H defined as the distance, measured orthogonally to the plates 2, between the two adjacent plates 2 defining said first passage 3. The mid-height of the first passage 3 is located at a distance H / 2 from each of the plates 2.

[0044] The interlayer partitions 11 have a length measured along the longitudinal direction z, and a width, less than the length, measured along the lateral direction x. The partitions 11 extend, in their length, parallel to the longitudinal direction z and are arranged at predetermined distances side by side along the lateral direction. The succession of interlayer partitions 11 forms a heat exchange structure in the first passage 3.

[0045] Each pair of adjacent interlayer partitions 11 delimits between them a channel 12 for the flow of the first fluid. Each channel 12 is delimited between the faces of the interlayer partitions 11 and the plates 2 forming the passage 3.

[0046] During operation, the fluid circulating in passage 3 is in indirect heat exchange via a plate 2, which forms a primary exchange surface, with the other fluid circulating in an adjacent passage 4. The partitions 11 form secondary exchange surfaces that intensify the heat exchange between the fluids, as well as stiffening the exchange passages by acting as spacers.

[0047] Preferably, all or part of the elements of the heat exchanger are made of aluminum or an aluminum alloy. In particular, at least the interlayer partitions 11 and the plates 2 are made of aluminum or an aluminum alloy.

[0048] According to the invention, the intermediate partitions 11 follow one another, along the lateral direction x, at intervals d defined each as the distance, measured parallel to the lateral direction x and at mid-height of the first passage 3, between two successive intermediate partitions 11, the ratio d / H being greater than or equal to 0.8.

[0049] Such a dimensional ratio makes it possible to form channels 12 that are sufficiently wide to facilitate the application of an anti-corrosion surface treatment to the channel partitions 12, which are formed by the surfaces of the plates 2 and the surfaces of the partitions 11 delimiting each channel 12 when the heat exchanger is assembled. The channels are wider than those conventionally formed by corrugated heat exchange structures and are therefore more accessible, allowing for higher-quality surface treatments in terms of treatment thickness homogeneity. In particular, wider channels help reduce pressure losses related to the circulation of the The anti-corrosion treatment product allows for complete coverage of the internal surface of the channels. This is particularly true when the treatment is carried out by immersion in a liquid bath, as is the case, for example, with anodizing or chemical conversion coatings, where larger channel openings allow for better bath circulation. Furthermore, the surfaces to be treated can be more thoroughly cleaned prior to the corrosion treatment, further improving the quality of the surface coating.

[0050] Preferably, the spacer partitions 11 and / or the plates 2 are coated after being brazed together. This maximizes the effectiveness of the corrosion protection. Thanks to the invention and the improved accessibility of the channels, the anti-corrosion treatment can be carried out after the stacking and brazing of the heat exchanger components. This preserves the quality and performance of the coating. Indeed, applying an anti-corrosion treatment to the partitions and / or plates before stacking them would cause degradation of the coating layers during high-temperature brazing in the brazing furnace, as well as contamination of the furnace itself by the degraded components of the treatment.

[0051] It should be noted that the use of a plate heat exchanger allows operation under small temperature differences and with reduced pressure losses, which improves the energy performance of the heat exchange process implemented. Plate heat exchangers also offer the advantage of very compact devices providing a large exchange surface area within a limited volume. Furthermore, thanks to its plate structure, the exchanger can connect more than two fluids for heat exchange, making it a compact device offering a large exchange surface area and more flexible operation compared to a tubular heat exchanger.

[0052] According to one embodiment, the d / H ratio is greater than or equal to 1 and / or less than or equal to 8, in particular less than or equal to 6. These ratios further improve channel accessibility. Preferably, the interlayer partitions 11 are spaced at intervals d of at least 5 mm, in particular ranging from 6 to 35 mm, and more preferably from 10 to 25 mm. The best compromise in the d / H ratio will be sought, taking into account the mechanical strength related to the pressure of the fluid circulating in the channels and the risk of the plates 2 being damaged during brazing.

[0053] Note that for reasons of mechanical strength, the gap width may depend on the pressure of the fluid flowing through it. The lower the fluid pressure, the wider the gap can be.

[0054] According to one embodiment, the intermediate partitions 11 have a partition width L1, measured parallel to the lateral direction x and at mid-height of said first passage 3, such that the Ll / H ratio is greater than or equal to 0.5, preferably between 0.8 and 3, preferably greater than or equal to 1 and / or less than or equal to 2.

[0055] Such dimensional ratios allow the interlayer partitions 11 to be sufficiently wide to ensure the mechanical strength of the first passages 3 and resistance to the pressure of the fluid flowing through them and to the tensile force exerted by the fluid. Larger intervals between the partitions 11, and therefore wider channels 12, can thus be used, while still ensuring the mechanical strength of the heat exchanger.

[0056] Furthermore, this allows for sufficiently massive partitions so that the mechanical strength of the resulting thermal structure is less rapidly affected by corrosion, thus extending the service life of the heat exchanger. Indeed, when the partitions 11 come into contact with a first corrosive fluid, corrosion initially affects the external surface of the partitions 11 and then propagates over time towards the internal part of the partitions. By using relatively thick partitions, compared to the height of the surface area of ​​the partitions in contact with the fluid, a smaller proportion of material is corroded and the mechanical strength of the stack is improved.

[0057] According to one embodiment, the spacer partitions 11 have a partition width L1 of at least 4 mm, preferably at least 5 mm, preferably even more than 15 mm, in particular between 8 and 12 mm, so as to ensure stability when stacked on the plate 2.

[0058] Note that the height of the intermediate partitions 11, measured orthogonally to the plates 2, is preferably substantially equal to, preferably slightly less than, the height H of the first passage 3.

[0059] Preferably, the channels 12 formed between the interlayer partitions 11 in said at least a first passage 3 are free of any heat exchange structure other than that formed by the series of interlayer partitions 11. In other words, the space formed between adjacent partitions 11 defines a free volume. By free volume, we mean a volume that does not present an obstacle to the flow of fluid.

[0060] According to one embodiment, said at least a first passage 3 is delimited at least partially by a pair of sealing bars 6 extending, in the direction of their length, parallel to the longitudinal direction z. The intermediate partitions 11 are arranged between the pair of sealing bars 6.

[0061] According to one embodiment, said first passage 3 has a heat exchange width L2, defined as the distance, measured parallel to the lateral direction x, between the two sealing bars 6 of said pair. In other words, the heat exchange width L2 corresponds to the width of the plates 2 delimiting said first passage 3, measured parallel to the lateral direction x, less the width of each of the two bars, measured parallel to the lateral direction x.

[0062] According to one embodiment, said at least a first passage 3 comprises at least 3 intermediate partitions 11 following one another in the first passage 3, preferably the first passage 3 comprises at least 8 intermediate partitions, preferably again between 10 and 50 intermediate partitions 11.

[0063] The number of intercalated partitions arranged per first pass 3 can be adapted according to its exchange width L2 so that N=L2 / (d+Ll), N being the number of channels 12 within the first pass 3.

[0064] According to one possibility shown in [Fig. 2] and [Fig. 3], at least one interlayer partition 11 is formed by at least one solid bar 11, 11a, 11b, which is generally parallelepiped in shape. The interlayer partitions 11 may have, in a cutting plane orthogonal to the longitudinal direction z, an external profile that is square or rectangular. The cross-sections of the bars and channels 12 may be square or rectangular. In other words, the interlayer partition 11 has a top face extending opposite one of the two adjacent plates 2, a bottom face extending opposite the other of the two adjacent plates 2, and a pair of lateral faces (114) connecting said top and bottom faces. The top, bottom, and lateral faces are planar.

[0065] It is possible that at least one partition 11 is formed of two bars lia, 11b joined together in the passage 3. The two bars 1la, 11b can be arranged side by side along the lateral direction x or superimposed one on top of the other along the stacking direction y.

[0066] The use of partitions with a generally parallelepiped shape leads to a simplification of the geometry of the heat exchange structure and the resulting exchange channels, with fewer changes in the orientation of their constituent surfaces. These surfaces can thus be more easily treated against corrosion. The use of parallelepiped partitions also facilitates their stable positioning when stacked on the passage separation plate 2.

[0067] According to another possibility shown in [Fig. 4], at least one intercalated partition 11 has an upper face 112 extending opposite one of the two adjacent plates 2 defining said first passage 3, a lower face 113 extending opposite the other of the two adjacent plates 2 defining said first passage 3, and a pair of lateral faces 114 connecting said upper and lower faces, each lateral face being oriented towards an adjacent channel 12 and having, in cross-section in a plane parallel to the lateral direction x and orthogonal to the plates 2, a profile concave towards said adjacent channel 12, in particular a concave shape with a radius of curvature r such that the ratio r / H is between 0.1 and 2, preferably between 0.2 and 0.5. Defining concave lateral faces makes it possible to avoid the formation of solder fillets at the junction between the lateral faces 114 and the plates 2, thus reducing the entry points to pitting by corrosion, and further improving the corrosion resistance of the exchanger.

[0068] It is specified that said at least one first passage 3 may comprise a succession of parallelepiped bars with exclusively straight lateral profiles, a succession of bars with exclusively concave lateral profiles, or possibly both parallelepiped and concave bars. Each of the first passages preferably presents successions of bars of the same geometry, but it remains conceivable that first passages 3 may have structures with different geometries.

[0069] It should also be noted that all or part of the first passages 3 for the flow of the first fluid can be configured according to the invention.

[0070] According to one embodiment, at least the plates 2 defining said at least one first pass have a thickness e such that the e / H ratio is at least 0.4, preferably at least 0.5, and even more preferably at most 1, in particular between 0.5 and 0.8. Using relatively thick plates allows the plates to be affected by corrosion less rapidly and compensates for any potential mass loss over time, thus limiting the risk of leaks and extending the service life of the heat exchanger. Corrosion initially affects the external surface of the plates, and a larger proportion of uncorroded material may remain within the plates. Preferably, the plates 2 have a thickness of at least 3 mm.

[0071] Note that at least one of the plates 2 can be formed from at least two parts of plates 2a, 2b superimposed on each other, preferably at least three parts of plates 2a, 2b, 2c, which makes it easier to gain in plate thickness, as shown schematically on [Fig.5].

[0072] According to one embodiment, all or part of the surfaces of the interlayer partitions 11 and / or the plates 2 delimiting the channels 12 are coated with at least one anodizing layer and / or at least one passivating layer, for example with trivalent chromium. All or part of the surface of the interlayer partitions 11 and / or the plates 2 may have a surface coating comprising trivalent chromium as the major component.

[0073] According to one possibility, all or part of the surfaces of the interlayer partitions 11 and / or the plates 2 are treated by anodizing, or electrochemical conversion. At least one oxide layer is formed on the surface of the parts by immersing them in an acid bath while they are subjected to an electric current. In the case of aluminum or aluminum alloy parts, the surface of the parts is modified by an electrochemical oxidation reaction of aluminum, forming an oxide layer. porous aluminum containing alumina. In particular, the surface treatment process can be of the Chromic Anodic Oxidation type.

[0074] According to another possibility, all or part of the surfaces of the interlayer partitions 11 and / or the plates 2 are treated by chemical conversion, or passivation, preferably with trivalent chromium. At least one layer of amorphous oxide is formed on the surface of the parts by immersing them in an acid bath, in particular a solution containing trivalent chromium salts.

[0075] According to an embodiment described with reference to [Fig. 2], the heat exchanger comprises at least a second passage 4 comprising at least one corrugated heat exchange structure 8 in the form of a corrugated product comprising a succession of wave crests 121 and wave bases 122 arranged against the plates 2 and alternately connected by fins 123. Said fins 123 follow one another along a corrugation direction of the heat exchange structure 8 which is parallel to the plates 2 and, in the illustrated example, parallel to the lateral direction x. Preferably, the fins have a thickness b of between 0.1 and 0.6 mm.

[0076] In the embodiment according to [Fig.2], the channels defined between each pair of consecutive fins 123 have a cross-section of overall rectangular shape, the fins extending globally parallel to the longitudinal direction z and parallel to the stacking direction y. It is also conceivable that the fins 123 form an angle of inclination with the y direction.

[0077] Note that as a heat exchange structure 8 of the corrugated product type, the different types of waves commonly used in plate and fin type heat exchangers can be used, namely straight waves, partially offset waves (of the "serrated" type), herringbone waves or herringbone waves, perforated or not.

[0078] According to one embodiment, the exchanger comprises an alternation of first passages 3 equipped with intercalated partitions 11 and second passages 4 equipped with corrugated exchange structures 8. The first passages 3 are without corrugated exchange structures 8.

[0079] According to one embodiment, at least one second pass 4 has a height (not referenced in the figures) defined as the distance, measured orthogonally to the plates 2, between the two adjacent plates 2 defining said second pass 4. The height H of at least one first pass 3 is preferably equal to the height of at least one second pass 4 multiplied by a factor ranging from 0.6 to 3, preferably from 0.8 to 2. In particular, said first pass 3 may have a height H of at least 1.5 mm, preferably at least 2 mm, preferably even more preferably at most 5 mm, in particular between 4 and 6 mm, which allows to have channels of a height suitable for good accessibility of channels 12 for their anti-corrosion treatment.

[0080] An exchanger according to the invention can in particular be used in a process for producing cooled or liquefied carbon dioxide. Carbon dioxide as a second fluid, in particular carbon dioxide in the supercritical state, and cooled or at least partially liquefied by heat exchange with a first refrigerant, preferably water.

[0081] An exchanger according to the invention can also be used in a process for cooling a first syngas stream as a first fluid by heat exchange with at least a second syngas stream as a second fluid, so as to produce at the outlet of the cooled syngas exchanger, the first syngas stream comprising hydrogen, carbon monoxide and water and the second syngas stream comprising hydrogen, carbon monoxide and possibly water in a lower content than the water content of the first syngas stream.The exchanger according to the invention is particularly advantageous for cooling wet syngas. Indeed, the water contained in the syngas stream condenses during cooling and, due to the presence of carbon dioxide and carbon monoxide, corrosive acidic condensates are formed with a pH of around 3. In particular, the first syngas stream comprises at least 5% (volume %) of water vapor, preferably between 3 and 80% (volume %) of water vapor.

[0082] Preferably, the heat exchanger is used so as to operate under a relatively small temperature difference, i.e., less than 4 °C, preferably between 1 and 3 °C. In other words, the temperature difference between the heat and refrigerant fluids is less than 4 °C, preferably between 1 and 3 °C, which makes it more energy-efficient. The first fluid is introduced into said at least one first passage 3 of the exchanger at a first temperature, the second fluid circulates in at least one second passage 4 of the exchanger, preferably counter-current to the first fluid, and exits the second passage at a second temperature, the temperature difference between the first and second temperatures being less than 4 °C, preferably between 1 and 3 °C.

[0083] With reference to the embodiment shown in [Fig. 6], the invention also relates to a heat exchange system comprising several heat exchangers according to the invention. In particular, several heat exchangers 1 can be supplied in parallel with at least the first fluid Fl and the second fluid F2. This increases the production capacity of the heat exchange system. Each heat exchanger forms a heat exchange body consisting of a stack of plates, first passes, and second passes. The The heat exchange system comprises a first fluid supply pipe 20 and a second fluid discharge pipe 21, connected respectively by pipes 10 to each fluid supply and discharge manifold 7 of a heat exchanger 1 of the system. The same principle applies to the second fluid F2 but is not illustrated for the sake of simplicity.

Claims

Demands

1. A plate heat exchanger configured to connect at least a first fluid and a second fluid for heat exchange, said exchanger comprising a plurality of plates (2) arranged parallel to each other and in a longitudinal direction (z) so as to define between them at least a set of first passages (3) for the flow of the first fluid and a set of second passages (4) for the flow of the second fluid, at least one first passage (3) having a height H defined as the distance, measured orthogonally to the plates (2), between the two adjacent plates (2) defining said first passage (3), said at least one first passage (3) comprising a succession of intercalated partitions (11) arranged so as to define within the first passage (3) a plurality of channels (12) for the flow of the first fluid parallel to the longitudinal direction (z), said intercalated partitions (11) succeeding one another,along a lateral direction (x) which is orthogonal to the longitudinal direction (z) and parallel to the plates (2), at intervals d each defined as the distance, measured parallel to the lateral direction (x) and at mid-height of said first passage (3), between two successive intermediate partitions (11), the exchanger being characterized in that the ratio d / H is greater than or equal to 0.

8.

2. Exchanger according to claim 1, characterized in that the ratio d / H is greater than or equal to 1 and / or less than or equal to 8, in particular less than or equal to 6.

3. Exchanger according to one of claims 1 or 2, characterized in that the intermediate partitions (11) follow one another at intervals d of at least 5 mm, preferably from 6 to 35 mm, more preferably from 10 to 25 mm.

4. Exchanger according to any one of the preceding claims, characterized in that the interlayer partitions (11) have a partition width Ll, measured parallel to the lateral direction (x) and at mid-height of said first passage (3), such that the ratio Ll / H is greater than or equal to 0.5, preferably between 0.8 and 3, preferably greater than or equal to 1 and / or less than or equal to 2.

5. Heat exchanger according to any one of the preceding claims, characterized in that the intercalated partitions (11) have a partition width L1 at least equal to 4 mm, preferably at least equal to 5 mm, preferably even more preferably at most equal to 15 mm, in particular between 8 and 12 mm.

6. Exchanger according to any one of the preceding claims, characterized in that said at least one first passage (3) is delimited at least partially by a pair of sealing bars (6) extending, in their lengthwise direction, parallel to the longitudinal direction (z), the intermediate partitions (11) being arranged between the pair of sealing bars (6).

7. Exchanger according to any one of the preceding claims, characterized in that said first pass (3) comprises at least 3 intermediate partitions (11), preferably at least 8 intermediate partitions (11), in particular from 10 to 50 intermediate partitions (11).

8. Exchanger according to any one of the preceding claims, characterized in that all or part of the channels (12) delimited between the intercalated partitions (11) each define a free volume for the flow of the first fluid.

9. Exchanger according to any one of the preceding claims, characterized in that the plates (2) defining said at least one first pass (3) have a thickness e, measured orthogonally to the plates (2), such that the ratio e / H is at least equal to 0.4, preferably at least equal to 0.5, preferably still at most equal to 1, in particular between 0.5 and 0.

8.

10. Exchanger according to any one of the preceding claims, characterized in that at least one intermediate partition (11) is formed by at least one solid bar (11, lia, 11b) of overall parallelepiped shape.

11. A heat exchanger according to any one of the preceding claims, characterized in that at least one interlayer partition (11) has an upper face (112) extending opposite one of the two adjacent plates (2) defining said first passage (3), a lower face (113) extending opposite the other of the two adjacent plates (2) defining said first passage (3), and a pair of lateral faces (114) connecting said upper and lower faces, each lateral face being oriented towards an adjacent channel (12) and having, in cross-section in a plane parallel to the lateral direction (x) and orthogonal to the plates (2), a profile concave towards said adjacent channel (12), in particular concave with a radius of curvature r such that the ratio r / H is between 0.1 and 2, preferably between 0.2 and 0.

5.

12. Exchanger according to any one of the preceding claims, characterized in that the surfaces of the interlayer partitions (11) and / or the plates (2) delimiting the channels (12) are coated in whole or in part with at least one layer of anti-corrosion coating, in particular with at least one layer resulting from a surface treatment by anodizing (30) or a surface treatment by chemical conversion.

13. Heat exchanger according to any one of the preceding claims, characterized in that at least a second pass (4) comprises at least one corrugated heat exchange structure (8) comprising a succession of wave crests (121) and wave bases (122) arranged against the plates (2) and connected alternately by fins (123), said fins (123) following one another along a corrugation direction of the heat exchange structure (8) which is in particular parallel to the lateral direction (x).

14. Exchanger according to claim 13, characterized in that it comprises an alternation of second passes (4) provided with corrugated exchange structures (8) and first passes (3) provided with intercalated partitions (11).

15. Use of a heat exchanger according to any one of claims 1 to 14 wherein carbon dioxide as a second fluid, in particular carbon dioxide in the supercritical state, is cooled or at least partly liquefied by heat exchange with the first fluid, the first fluid preferably being water, so as to produce at the outlet of the heat exchanger a stream of cooled or liquefied carbon dioxide.

16. Use of a heat exchanger according to any one of claims 1 to 14 wherein a first syngas stream as a first fluid is cooled by heat exchange with at least a second syngas stream as a second fluid, so as to produce at the outlet of the cooled syngas exchanger, the first syngas stream comprising hydrogen, carbon monoxide and water and the second syngas stream comprising hydrogen, carbon monoxide and optionally water in a lower content than the water content of the first syngas stream.

17. A method for manufacturing a heat exchanger according to any one of claims 1 to 14, said method comprising the following steps: - a) stack the plurality of plates (2) parallel to each other and in a longitudinal direction (z) so as to define between them said at least one set of first passes (3) for the flow of the first fluid and said at least one set of second passes (4) for the flow of the second fluid, - b) arrange in at least a first passage (3) said succession of intercalated partitions (11) so as to define within the first passage (3) the plurality of channels (12) for the flow of the first fluid, - c) braze the stack of plates (2), including the two adjacent plates (2) defining the first passage (3) and the intermediate partitions (11), - d) after step c), coat all or part of the surfaces of the interlayer partitions (11) and / or the adjacent plates (2) delimiting the channels (12) with an anti-corrosion coating, in particular with at least one layer obtained by anodizing (30) and / or at least one layer obtained by chemical conversion (30).

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