Method for manufacturing a heat exchange graphite assembly, corresponding assembly, and tube bundle heat exchanger including the same

Abstract

This method includes the steps of providing a tube (2), a tube sheet (4), and baffles of a graphite material in a non-impregnated state; arranging the non-impregnated tube, tube sheet, and baffles in the exact positions in which they are intended to be present so as to form a functional clearance between the tube and the tube sheet; impregnating the graphite with an impregnation different from cement to fill the pores and forming an adhesive film (30) made from the above-mentioned impregnation in the above-mentioned clearance to firmly attach the tube to the tube sheet. In particular, this method can avoid any problems due to the possibility of corrosion and leakage, significantly reduce the duration, improve in terms of environmental concerns, and increase both the heat transfer area and the thermal conductivity of the final exchanger.

Description

Technical Field

[0001] The present invention relates to the technical field of shell-and-tube heat exchangers. More specifically, it relates to an improved manufacturing method of a heat exchange graphite assembly that is part of such a shell-and-tube exchanger. The present invention also relates in particular to a heat exchange graphite assembly obtained according to this method, and to an exchanger provided with such a graphite assembly.

Background Art

[0002] Numerous types of heat exchangers are known, including, among others, plate-type, block-type, or fin-type exchangers. The present invention relates more specifically to shell-and-tube heat exchangers, which typically include a shell portion that houses a so-called heat exchange assembly. In the present invention, the latter is preferably made of graphite because this material can withstand highly corrosive fluids and high temperatures.

[0003] The above-mentioned graphite assembly includes first, a plurality of tubes that form a bundle, and two so-called tube sheets or tube plates provided at opposite ends of the aforementioned tubes. Further, one or more baffles are provided at one or more intermediate positions with respect to the longitudinal direction of the tubes. The shell portion of the exchanger defines an inlet chamber and an outlet chamber for a first fluid, also called a process fluid, both of which extend substantially along the main axis of the exchanger. Further, this shell portion also includes an inlet pipe and an outlet pipe for a second fluid, also called a service fluid, both of which extend substantially in the transverse direction.

[0004] In use, a first fluid, typically a liquid or a gas, flows from an inlet chamber, through the internal space of the pipe, and then to an outlet chamber. In parallel, a second fluid, typically water or steam water, flows from an inlet pipe of a space defined between the inner surface of the shell and the outer surface of the pipe. Under these conditions, heat exchange between the above-mentioned fluids takes place through the pipe wall. To implement it properly and reliably, the tube sheet needs to be completely sealed against the inner wall of the shell.

[0005] As an example of a tube bundle heat exchanger of the above type, there is an exchanger sold by the applicant under the trade name POLYTUBE. The manufacturing method of a heat exchange graphite assembly, which is part of this exchanger, is as follows.

[0006] First, the tubes, tube sheets, and baffles are typically subjected to an impregnation step in a container containing a suitable resin. Thereafter, further machining steps are performed on these impregnated parts. In particular, the opposite ends of the tubes are tapered so as to be fixed in holes provided in each tube sheet.

[0007] This tapered shape can form a free space between the outer wall of the tube facing the wall of each hole. Then, this space is filled with cement, thereby attaching the tube and the tube sheet to each other. In a typical case, this cement is a mixture of a phenolic resin and graphite powder.

[0008] The POLYTUBE exchanger has demonstrated very satisfactory performance over several decades. In fact, it defines a large heat transfer area and exhibits excellent thermal conductivity and high mechanical strength.

[0009] As a modification of this graphite assembly, other measures have been proposed.

[0010] First, Patent Document 1 discloses a tube bundle in which each tube is surrounded by graphite fibers. This makes it possible to improve the mechanical strength of these graphite tubes.

[0011] Furthermore, Patent Document 2 describes an exchanger that is a modified phenolic resin graphite extrusion tube in which each tube is treated at a medium temperature of 300°C. Due to this treatment, its thermal stability and chemical stability are improved, and the linear expansion coefficient is significantly reduced.

[0012] Finally, Patent Document 3 proposes a heat exchanger in which tube plates define a row of chambers arranged side by side. That is, the fluid reciprocates and circulates between these tube plates.

[0013] On the other hand, Patent Documents 4, 5, and 6 disclose several methods of impregnating graphite, which is a part of the exchanger. In particular, Patent Document 4 proposes placing graphite elements in a solution made from a PTFE prepolymer.

[0014] Patent Document 7 describes a graphite heat exchange assembly including a silicon carbide tube insert. Silicon carbide is a specific material whose requirements are different from those of graphite.

Prior Art Documents

Patent Documents

[0015]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Summary of the Invention

Problems to be Solved by the Invention

[0016] From the above, it is required to improve the manufacturing process of the heat exchange graphite assembly described above and to improve the tube bundle exchanger equipped with this assembly.

[0017] Therefore, one object of the present invention is to provide a manufacturing method that enables substantially avoiding any problems caused by corrosion and leakage of the above-described assembly.

[0018] A further object of the present invention is to provide such a manufacturing method that significantly reduces its overall duration and labor time.

[0019] A further object of the present invention is to provide such a manufacturing method that is improved with respect to environmental concerns.

[0020] A further object of the present invention is to provide such a manufacturing method that can further increase both the heat transfer area and the thermal conductivity of the final exchanger.

[0021] A further object of the present invention is to provide such a manufacturing method that improves the transportation of spare parts not only in terms of cost but also in terms of the risk of mechanical damage.

[0022] A further object of the present invention is to provide such a method that enables the manufacture of a heat exchange graphite assembly that can be easily incorporated into the shell of an exchanger of the prior art.

[0023] Furthermore, a further object of the present invention is to provide such a method that results in the manufacture of an exchanger having substantially the same mechanical strength and pressure design as the prior art.

Means for Solving the Problems

[0024] At least one of the above objects is achieved by a first object of the present invention, which is a method for manufacturing a heat exchange graphite assembly (1), said assembly being intended to form part of a shell and tube heat exchanger (I), said assembly comprising: - a plurality of tubes (2) forming a bundle (20); - two tube sheets (4, 5) provided at opposite ends of said tubes, each tube sheet including through holes (20) for receiving said tubes; - at least one baffle (6, 7) provided at an intermediate position of said tubes, each baffle including an opening (60) for passing said tubes. The manufacturing method includes: - providing said tubes, said tube sheets, and said baffles of a graphite material in a so-called non-impregnated state or porous state, i.e., having a porosity of a first value; - arranging said tubes, said tube sheets, and said baffles in a porous state substantially in the exact positions in which they are intended to be present, so as to form a functional clearance (230) between the opposing walls of said tubes and the opposing walls of said holes; - impregnating said tubes, said tube sheets, and said baffles with an impregnation different from cement; filling the pores of said tubes, said tube sheets, and said baffles to impart to the graphite material a porosity of a second value that is sufficiently lower than the first value; and forming an adhesive film (30) made from said impregnation in said clearance to firmly attach said tubes to said tube sheets.

[0025] According to an advantageous feature of this manufacturing method: - the transverse dimension or thickness (t230) of said clearance (230) is from 0.005 mm to 0.5 mm, particularly from 0.01 mm to 0.1 mm; - no cement is inserted into said clearance; - impregnating said tubes, said tube sheets, and said baffles placing the tube, the tube sheet, and the baffle in a container; filling the container, especially from the bottom of the container, with the impregnating material; bringing the tube, the tube sheet, and the baffle into contact with the impregnating material, and removing the impregnating material, including: - the contact time between the tube, the tube sheet, and the baffle and the impregnating material is 5 to 72 hours; - the method further includes a curing step of heating the tube, the tube sheet, and the baffle at a temperature of 50°C to 250°C for a duration of 5 to 24 hours after the impregnating step; - the thickness (t30) of the adhesive film (30) is 0.005 mm to 0.5 mm, especially 0.01 mm to 0.1 mm; - the thickness (t22) of the tube wall (22) is 1 mm to 7 mm, preferably 2 mm to 5 mm; - the distance (S2) between the outer surfaces of two adjacent tubes is 0.5 mm to 6 mm, preferably 1 mm to 3 mm.

[0026] A second object of the present invention is a heat exchange graphite assembly (1), especially manufactured by the method as described above, the assembly being intended to be part of a shell-and-tube heat exchanger (I), the assembly comprising: - a plurality of tubes (2) forming a bundle (20); - two tube sheets (4, 5) provided at opposite ends of the tube, each tube sheet including through holes (20) for receiving opposite ends (3, 3') of the tube; - at least one baffle (6, 7) provided at an intermediate position of the tube, each baffle including an opening (60) for passing the tube; - the tube, the tube sheet, and the baffle are made of a graphite material; the graphite material is at least partially filled with an impregnating material different from cement; The graphite assembly (1) has, at each opposite end (3, 3') in each tube, a continuous adhesive film (30) made from the impregnated material interposed between the opposing walls of the tube (2) and the opposing walls of the hole (20), attaching each end of each tube to each tube sheet.

[0027] According to an advantageous feature of this heat exchange graphite assembly, - The thickness (t30) of the adhesive film (30) is from 0.005 mm to 0.5 mm, particularly from 0.01 mm to 0.1 mm, - The thickness (t22) of the tube wall (22) is from 1 mm to 7 mm, advantageously from 2 mm to 5 mm, - The distance (S2) between the outer surfaces of two adjacent tubes is from 0.5 mm to 6 mm, advantageously from 1 mm to 3 mm, - The tube has two straight ends (3, 3').

[0028] A third object of the present invention is a shell-and-tube heat exchanger, which - includes a heat exchange graphite assembly (1) as described above, and - a shell part (100) surrounding the assembly, wherein the tube sheets (4, 5) of the assembly are attached to the inner wall of the shell part, and the shell part - has first inlet means (110, 112, 114) for the inlet of a first fluid to the tubes (2) of the assembly, - has first outlet means (120, 122, 124) for the outlet of the first fluid from the tubes (2) of the assembly, - has second inlet means (150) for the inlet of a second fluid to a heat exchange space (140) formed between the opposing walls of the tubes and the opposing walls of the shell part, and - has second outlet means (150) for the outlet of the second fluid from the heat exchange space (140).

[0029] The present invention will be described below with reference to the accompanying drawings, which are provided as non-limiting examples.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 6

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Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

DETAILED DESCRIPTION OF THE INVENTION

[0031] The following reference numerals are used throughout this description. I Heat exchanger according to the present invention 1 Assembly of the present invention, 2 Tubes, 20 Bundles D2 Diameter of 2, S2 Spacing between tubes 2 22 Annular wall of the tube, t22 Thickness 23, 24 Inner and outer surfaces of the tube 3, 3' Opposite ends of the tube, 4, 5 Tube sheets 40 Through holes in the tube sheet, 6, 7 Baffles 60 Opening of the baffle, D60 Diameter of 60 100 Shell part, A100 Longitudinal axis of the shell part 110 Cover of the exchanger I, 112 Inlet duct of 110 114 Intake chamber, 120 Bottom of the exchanger I 122 Outlet duct of 120, 124 Discharge chamber 130 Main cylindrical region of the exchanger I 140 Heat exchange space 150, 160 Inlet pipe and outlet pipe of I, 201 Preform 230 Clearance between the tube and the tube sheet, T230 Thickness 235 Intervening space between the tube and the baffle 30 Film for bonding the tube and the tube sheet, t30 Thickness II Exchanger in the prior art 502 and below: The same as 2 and below 530 cement layer, t530 thickness, LP pore line

[0032] Figure 1 shows a heat exchanger, generally referred to as I. First, this exchanger includes a shell 100, whose main longitudinal axis is shown as A100. This shell defines a cover 110 at one first end, a bottom 120 at the opposite end, and a main cylindrical region 130. As will be described in more detail, region 130 defines a so-called heat exchange space 140.

[0033] The above-mentioned shell 100 houses a heat exchange graphite assembly, generally referred to as 1 in the present invention. As shown in Figure 2, this assembly basically includes a plurality of tubes 2, two end tube sheets 4 and 5, and baffles 6 and 7. The structure and manufacturing method of this assembly will be described in detail later.

[0034] Cover 110 is provided with a duct 112 intended to be an inlet for a first fluid or process fluid to the tubes 2 of assembly 1. This inlet is located upstream and is connected to a source of this fluid, not shown. The above-mentioned duct 112 is connected to the heat exchange space 140 via an intake chamber 114.

[0035] Furthermore, bottom 120 is provided with a further duct 122 for an outlet of the first fluid to the outside of the longitudinal tubes 2. This duct is provided downstream of the heat exchange space 140 via a discharge chamber 124. In a manner known per se, duct 122 is connected to a recovery tank, not shown.

[0036] In a manner known per se, shell 100 further includes an inlet pipe 150 and an outlet pipe 160 for a second fluid or service fluid, each of which is connected to a source and a recovery tank. The above-mentioned second fluid is intended to exchange heat with the first fluid in the above-mentioned heat exchange space 140.

[0037] Figure 3 shows one of the tubes 2 that are identical to each other and form the bundle 20. The tube 2 has a circular cross-section and defines an annular wall 22 having an inner surface 23 and an outer surface 24. The characteristic dimensions of this tube are detailed at the end of this description.

[0038] The tube 2 is made of graphite and is manufactured by any suitable process. The latter typically includes at least some of the known steps in mixing, extrusion, carbonization, and high-temperature treatment. The graphite material of this tube is the same as that of the prior art and advantageously has a thermal conductivity of at least 20 W.m.K., typically 50 W.m.K to 80 W.m.K.

[0039] Furthermore, this graphite material has a rather high first value of so-called porosity. As a result, the liquid penetrates into this graphite. Therefore, there is a need to impregnate this graphite to make it suitable for the intended final use.

[0040] Figure 4 shows one of the tube sheets 4, and it should be noted that the other 5 is the same. This tube sheet 4 is made of substantially the same material as the tube 2. Furthermore, the manufacturing process of this sheet and its characteristics are the same as those of each tube.

[0041] The tube sheet 4 having a cylindrical shape is provided with means adapted to ensure attachment and sealing on the inner wall of the shell portion 100. These means are not shown but are of any suitable type known to those skilled in the art.

[0042] The tube sheet 4 is provided with a plurality of through holes 40 extending perpendicular to its main surface. These holes are manufactured by a suitable method, especially machining. Referring to Figure 5, looking at the diameter D40 of each hole 40, typically, the difference (D40 - D2) is 0.01 mm (millimeter) to 1 mm. As will be detailed later in this specification, the value of this difference is important because it determines the thickness of the adhesive film between the tube and the tube sheet.

[0043] Figure 6 shows one of the baffles, referred to as 6, but it should be noted that the structure of the other baffle 7 is the same. The material, manufacturing process, and characteristics of this baffle are the same as those of the tube sheets 4 and 5 and are also known per se.

[0044] The baffle 6 is provided with a plurality of through openings 60 extending perpendicular to its main surface. These openings are manufactured by appropriate methods, particularly machining. Referring to Figure 7, looking at the diameter D60 of each opening 60, unlike D40, the value of D60 is not so important. In a method known per se, the difference (D60 - D2) is sufficient to enable the easy assembly of the tube and the baffle. Furthermore, this difference is not too large to avoid the fluid making occasional detours between the tube and the walls of the holes provided in the baffle.

[0045] An important feature of the present invention is to form a preform 201 composed of the same mechanical elements as those of the final heat exchange assembly 1. In an advantageous embodiment, this preform is directly installed in a container (not shown) that conforms to the acceptance of the product. First, one tube sheet 4, as well as the baffles 6 and 7, are fixed to the wall of this container by any suitable mechanical means.

[0046] Thereafter, each tube is moved along its main direction in accordance with the arrow F2 in Figure 8. The first end 3 of each tube is sequentially inserted into the openings of the various baffles and the holes of the tube sheet 4. Thereafter, the other tube sheet 5 is moved along the arrow F5 so that its hole aligns with the opposite end 3' of the tube. This operation is substantially similar to a part of the manufacture of Polytube in the prior art, but it is different in that it is performed with non-impregnated graphite.

[0047] At the end of this operation, as shown in FIG. 9, the outer surface 24 of each tube 2 forms a clearance 230 with the opposing wall 41 surrounding the hole 40 of the tube sheet. The short-side dimension or thickness t230 of this clearance is substantially half of the difference (D40 - D2) defined above, i.e., 0.005 mm to 0.5 mm, particularly 0.01 mm to 0.1 mm. In FIG. 9, the clearance 230 is shown as a complete ring. In reality, the tube 2 and the hole 40 may not be exactly concentric. Therefore, the value of t230 described above is the average value across the peripheral portion of the clearance described above.

[0048] Similarly, as shown in FIG. 10, the outer surface 24 of each tube 2 forms an intervening space 235 with the opposing wall surrounding the opening of the baffle. Note that FIGS. 9 and 10 are not to actual scale for clarity.

[0049] The tubes, tube sheet, and baffle define a preform 201, and these are arranged relative to one another in substantially the final positions they are intended to be in. Further, at this stage, these elements are not yet impregnated and are still porous.

[0050] Note that the tubes, tube sheet, and baffle are not yet rigidly attached to one another. However, the clearance 230 between the tube and the tube sheet is small, and the baffle is suitable for ensuring a stabilizing function. Therefore, the elements described above are less likely to move relative to one another throughout the entire process.

[0051] Thereafter, the impregnation step of the method in the present invention is performed. The impregnating material is selected to satisfy two different functions. First, this article is impregnated into the pores of the graphite material by a method known per se. Further, this article fills the clearance 230 and causes the wall of the tube to be in close contact with the opposing wall of the tube sheet.

[0052] As an example, the impregnating material can be a phenolic resin such as those used in the manufacture of prior art POLYTUBE. As an alternative, one of ordinary skill in the art can select other suitable articles such as other types of resins.

[0053] In a practical method, this impregnation step can be performed, for example, as follows. First, the impregnating material is placed in a container in which the preform 201 is installed. In an advantageous method, in order to suppress the swirling phenomenon, this injection is performed from the bottom of the container. Thereby, it is possible to avoid large movement of mechanical elements that are part of the preform.

[0054] Once the impregnating material covers the entire preform, a contact step between the preform and the impregnating material is performed. In an advantageous method, the duration of this contact step, also called the contact duration, is typically 5 hours to 72 hours. Thereafter, the impregnating material is finally discharged, preferably from the bottom of the container.

[0055] In a further step, the impregnated preform is heated at a temperature of preferably 50°C to 250°C for 5 hours to 24 hours. This heating step is known per se and can thermoset the resin and make the graphite impermeable.

[0056] After performing the above steps, the impregnated product is in a so-called cured or solidified state. Thus, this makes both the tube 2 and the tube sheets 4 and 5 liquid-tight. In this so-called impregnated state, the components of the preform 201 here have a porosity of a second value that is much lower than the first value described above. Since the porosity thus becomes much lower, the elements of the final assembly are here adapted to their intended use.

[0057] Also, by this impregnation, a continuous film 30 is formed that fills the above-described clearance 230 as shown in FIGS. 12 and 13. This film has a thickness t30 that corresponds to the dimension t230 of the clearance, i.e., 0.005 mm to 0.5 mm, particularly 0.01 mm to 0.1 mm. This film 30 makes a continuous intimate contact that can firmly attach the tube 2 to each of the tube sheets 4 and 5. For the same reasons as detailed above for the clearance 230, the film 30 is shown as a complete ring but may have a slightly different shape. Under this condition, t30 is the average value across the peripheral portion of the above-described film.

[0058] On the other hand, the cured impregnation fills at least partially the intervening space 235. Thereby, an intervening layer (not shown) is formed between the tube and the baffle. Contrary to the film 30, this layer does not need to be continuous and does not need to form an intimate contact between the tube and the baffle.

[0059] By the above-described steps, particularly the formation of the intimate contact between the tube and the tube sheet, the final assembly 1 is formed. The latter is then housed in the shell portion 100 according to any suitable method. This step is substantially the same as that applied to the manufacture of the prior art exchange POLYTUBE as described above. This is advantageous in terms of manufacturing simplicity for the operator.

[0060] According to the present invention, the above object can be achieved. In this regard, the applicant emphasizes that the applicant has identified the core problems that bring some disadvantages to the prior art exchangers. In particular, the applicant has clarified that the use of cement causes some technical problems.

[0061] As a note, cement can be defined as a mixture of solid particles and a binder. When this mixture is disposed between the opposing walls of the tube and the opposing walls of the tube sheet, it is heat-treated to irreversibly cure the binder and ensure the mutual adhesion between the tube and the tube sheet.

[0062] To show the disadvantages of using cement, reference is now made to FIGS. 14 to 17 showing the exchanger II in the prior art. In these figures, mechanical elements similar to those of exchanger I are given the same reference numerals with the addition of the number 500.

[0063] As shown in FIG. 14 on a large scale, in the prior art, each tube 502 has a tapered end 503. The latter defines a free space 730 by opposing walls surrounding the holes 540 of the tube sheet 504. Filling this space 730 with cement forms a layer, referred to as 530 in this FIG. 14.

[0064] This layer 530 is provided with a substantially continuous pore line extending at the boundary between the cement and the graphite material. This line, referred to as LP, is schematically shown in FIG. 18 which shows detail XVIII of FIG. 14 on a larger scale. The applicant acknowledges that these pores are a weakness with respect to the tightness of the assembly. In fact, this pore line forms a so-called preferential path in the possible chemical erosion by the process fluid.

[0065] On the contrary, the essential feature of the present invention anticipates not using the cement that has hitherto been used for attaching the tubes to the tube sheet. In the present invention, the cement is replaced by the above-described continuous adhesive film 30 made from the same article that also enables impregnation of the porous graphite.

[0066] In other words, this article ensures an additional function of adhesion in addition to the normal function of impregnation. On the contrary, it is emphasized that the cement is not adapted to simultaneously fulfill these two above-mentioned functions.

[0067] Under these conditions, the thickness t30 of this film 30 (see FIG. 12) is advantageously much smaller than the t530 of the cement layer 530 (see FIG. 17). Furthermore, each tube end, such as that referred to as 3 in FIG. 13, is straight, which is simpler with regard to the concerns of the manufacturing process of such tubes.

[0068] Furthermore, by not using cement, many costs can be saved in the manufacture of the assemblies according to the present invention. In summary, in the prior art, the tubes, tube sheets, and baffles are first subjected to separate impregnation steps and then some troublesome mechanical operations are performed. On the other hand, the present invention anticipates pre-arranging these non-impregnated elements and then performing a single impregnation step. As an example, it can be estimated that according to the present invention, the work skill is 50% less and the process operation is 80% less.

[0069] Also, by not using cement, the overall tube arrangement can be substantially changed. In fact, in the manual assembly process of the prior art, a minimum distance described as S502 in FIG. 17 is required between two adjacent tubes 502. This distance is typically at least 7 mm and is necessary not only to leave the free space 730 in FIG. 14 but also for the operator's hand to have access.

[0070] In contrast, since the operator does not need to access between these adjacent tubes, the present invention allows adjacent tubes to be arranged much closer together than in the prior art. Under these conditions, as shown in FIG. 12, the distance S2 between the outer walls 24 of adjacent tubes can be much smaller than that of the prior art S502. As an example, the value of this distance S2 is from 0.5 mm to 6 mm, preferably from 1 mm to 3 mm.

[0071] Furthermore, in the previous assembly process, it is necessary to use tubes having a fairly thick wall 522. This makes it particularly difficult for the operator to handle. The wall thickness of each tube 502 referred to as t522 in FIG. 15 is typically more than 5 mm. Also, FIG. 15 schematically shows the layer 530 as well.

[0072] The assembly of the present invention may include prior art tubes having a fairly thick wall as described in the previous paragraph. However, in a preferred method, in the present invention, much thinner tubes with a much smaller wall thickness can be used. As an example, the above-mentioned thickness t22 of the wall 22 is from 1 mm to 7 mm, preferably from 2 mm to 5 mm. Further, with respect to FIG. 3, the inner diameter d2 of the tube is preferably from 5 mm to 40 mm, and the outer diameter D2 of the tube is preferably from 7 mm to 55 mm.

[0073] Therefore, for this preferred variant of the present invention, it is considered that more tubes can be installed in a tube sheet of the same size. That is, considering that the thickness of the tube is small, the present invention significantly improves the thermal performance of the heat exchanger. As an example, it can be estimated that the heat exchanger of the present invention, in which the tubes are thinner and the adjacent tubes are closer compared to the prior art, has a heat transfer area that is about twice as high as that of the prior art heat exchanger. Also, the thermal conductivity can be twice as high.

[0074] The present invention also brings several advantages regarding the proper implementation of the heat exchanger. That is, in the prior art, there are several defects in manual installation, one of which is generally called "over-cementation". When this occurs, cement accidentally enters some of the tubes and forms so-called flakes that deposit on the inner walls of the tubes. Over time, some of these flakes are likely to be peeled off from the tubes by the liquid flow. These cement pieces can also move along the entire heat exchanger and cause obstructions. In the present invention that does not use cement, this occasional phenomenon is avoided.

[0075] The present invention can further make both the graphite assembly and the entire heat exchanger smaller in design. Under such conditions, less civil engineering technology is required, the carbon dioxide related to transportation is reduced, and less steel is needed for the shell manufacturing.

[0076] In addition, the present invention also makes it possible to reduce the transportation risk. In this regard, various mechanical elements can be delivered in the form of a space-saving kit from the main manufacturing plant. These elements are then considered to be assembled with each other at the local affiliate company.

[0077] It should be noted that the above-mentioned Patent Document 4, Patent Document 5, and Patent Document 6 are only a part of the background art of the present invention. In fact, these documents only relate to the impregnation process of the heat exchanger. However, they do not describe the mutual assembly of the components of this heat exchanger.

[0078] Furthermore, the heat exchanger of Patent Document 7 does not face the same technical problem as the present invention. In fact, the silicon carbide forming the tube insert of this heat exchanger is itself impermeable. Therefore, this material does not have a porous state within the meaning of the present invention and does not require an impregnation step.

Explanation of Signs

[0079] I Heat exchanger in the present invention 1 Assembly of the present invention 2 Tube 20 Bundle D2 Diameter 2 of tube 2, S2 Spacing between tubes 2 22 Annular wall of the tube, t22 Thickness 23, 24 Inner and outer surfaces of the tube 3, 3’ Opposite ends of the tube 4, 5 Tube sheet 40 Through-hole of the tube sheet 6, 7 Baffle 60 Opening of the baffle, D60 Diameter of 60 100 Shell part, A100 Longitudinal axis of the shell part 110 Cover of heat exchanger I 112 Inlet duct of 110 114 Intake chamber 120 Bottom of heat exchanger I 122 Outlet duct of 120 124 Discharge chamber The main cylindrical region of the 130 exchanger I 140 Heat exchange space 150, 160 The inlet pipe and the outlet pipe of I 201 Preform 230 Clearance between the tube and the tube sheet, T230 thickness 235 Intervening space between the tube and the baffle 30 Film for adhering the tube and the tube sheet, t30 thickness II Exchanger in the prior art 502 or less: the same as 2 or less 530 Cement layer, t530 thickness LP Pore line

Claims

1. A method for manufacturing a heat exchange graphite assembly (1), said assembly being intended to be part of a shell-and-tube heat exchanger (I), said assembly comprising: - a plurality of tubes (2) forming a bundle (20); - two tube sheets (4, 5) provided at opposite ends of said tubes, each tube sheet including through-holes (20) for receiving said tubes, the tube sheets (4, 5); - at least one baffle (6, 7) provided at an intermediate position of said tubes, each baffle including an opening (60) for passing said tubes, the baffle (6, 7); The manufacturing method comprises: - providing said tubes, said tube sheets, and said baffle of a graphite material in a so-called non-impregnated state or porous state, i.e., having a porosity of a first value; - arranging said tubes, said tube sheets, and said baffle in a porous state substantially in the exact positions in which they are intended to be present, to form a functional clearance (230) between the opposing walls of said tubes and the opposing walls of said holes; - impregnating said tubes, said tube sheets, and said baffle with an impregnation different from cement; filling the pores of said tubes, said tube sheets, and said baffle to impart to the graphite material a porosity of a second value that is sufficiently lower than the porosity of said first value; and forming an adhesive film (30) made of said impregnation in said clearance to firmly attach said tubes to said tube sheets.

2. The manufacturing method according to claim 1, wherein the transverse dimension or thickness (t230) of said clearance (230) is from 0.005 mm to 0.5 mm, particularly from 0.01 mm to 0.1 mm.

3. The manufacturing method according to claim 1 or 2, wherein no cement is inserted into said clearance.

4. The impregnation of said tubes, said tube sheets, and said baffle comprises: placing said tubes, said tube sheets, and said baffle in a container; filling said container with said impregnation, particularly from the bottom of said container; bringing said tubes, said tube sheets, and said baffle into contact with said impregnation; and removing said impregnation.

5. The contact time between the tube, the tube sheet, and the baffle and the impregnated material is 5 hours to 72 hours, the manufacturing method according to any one of claims 1 to 4.

6. After the step of impregnating, further comprising a curing step of heating the tube, the tube sheet, and the baffle at a temperature of 50°C to 250°C for a duration of 5 hours to 24 hours, the manufacturing method according to any one of claims 1 to 5.

7. The thickness (t30) of the adhesive film (30) is 0.005 mm to 0.5 mm, particularly 0.01 mm to 0.1 mm, the manufacturing method according to any one of claims 1 to 6.

8. The thickness (t22) of the tube wall (22) is 1 mm to 7 mm, preferably 2 mm to 5 mm, the manufacturing method according to any one of claims 1 to 7.

9. The distance (S2) between the outer surfaces of two adjacent tubes is 0.5 mm to 6 mm, preferably 1 mm to 3 mm, the manufacturing method according to any one of claims 1 to 8.

10. A heat exchange graphite assembly (1), particularly manufactured by the method according to any one of claims 1 to 9, wherein the assembly is intended to be part of a shell and tube heat exchanger (I), and the assembly comprises - a plurality of tubes (2) forming a bundle (20); - two tube sheets (4, 5) provided at opposite ends of the tubes, each tube sheet including a through hole (20) for receiving the opposite ends (3, 3') of the tubes; - at least one baffle (6, 7) provided at an intermediate position of the tubes, each baffle including an opening (60) for passing the tubes; - the tubes, the tube sheets, and the baffles are made of a graphite material; the graphite material is at least partially filled with an impregnated material different from cement; the heat exchange graphite assembly (1) has, at each opposite end (3, 3') of each tube, a continuous adhesive film (30) made of the impregnated material interposed between the opposing walls of the tube (2) and the opposing walls of the hole (20) to attach each end of each tube to each tube sheet.

11. The thickness (t30) of the adhesive film (30) is 0.005 mm to 0.5 mm, particularly 0.01 mm to 0.1 mm, the heat exchange graphite assembly according to claim 10.

12. The thickness (t22) of the tube wall (22) is from 1 mm to 7 mm, preferably from 2 mm to 5 mm, for the heat exchange graphite assembly according to claim 10 or 11.

13. The distance (S2) between the outer surfaces of two adjacent tubes is from 0.5 mm to 6 mm, preferably from 1 mm to 3 mm, for the heat exchange graphite assembly according to any one of claims 10 to 12.

14. The tube has two straight ends (3, 3'), for the heat exchange graphite assembly according to any one of claims 10 to 13.

15. A shell-and-tube heat exchanger, - a heat exchange graphite assembly (1) according to any one of claims 10 to 14, and - a shell part (100) surrounding the assembly, wherein the tube sheets (4, 5) of the assembly are attached to the inner wall of the shell part, and the shell part - first inlet means (110, 112, 114) for an inlet of a first fluid to the tube (2) of the assembly (1), - first outlet means (120, 122, 124) for an outlet of the first fluid from the tube (2) of the assembly (1), - second inlet means (150) for an inlet of a second fluid to a heat exchange space (140) formed between the opposing walls of the tube and the opposing walls of the shell part, and - second outlet means (150) for an outlet of the second fluid from the heat exchange space (140), a shell-and-tube heat exchanger.

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