Dismantling method of heat exchanger

Abstract

The objective of the present invention is to provide a method for dismantling a heat exchanger, wherein the method for dismantling the heat exchanger has excellent workability, allows for further reduction of radiation dose, and enables the tube plate to be easily reused as a metal material. The present invention provides a method for dismantling a heat exchanger, wherein the heat exchanger is used in a nuclear facility and comprises a heat transfer tube; a tube plate for fixing the heat transfer tube; and a cylindrical body for accommodating the heat transfer tube and the tube plate, wherein the heat transfer tube comprises an arc portion; and a straight tube portion that is parallel to the central axis of the body and extends from one end of each of the arc portions to penetrate the tube plate from the front to the rear, and the straight tube portion is welded to the tube plate on the rear side of the tube plate, and the dismantling method comprises a process of removing the arc portion of the heat transfer tube; a process of removing the weld portion where the straight tube portion is welded to the tube plate by slicing the tube plate; and a process of drawing out the straight tube portion after the process of removing the arc portion and the process of removing the weld portion.

Description

Technology Field

[0001] The present invention relates to a method for dismantling a heat exchanger. Background Technology

[0002] When upgrading or decommissioning facilities at nuclear power plants, equipment such as aging tanks and heat exchangers is removed. Radioactive materials are attached to these devices. Removing the parts contaminated with such radioactive materials and reusing the parts that are not contaminated, or those that can be decontaminated with only small amounts of radioactive material, as raw materials for metals enables a reduction in radioactive waste.

[0003] In the case of heat exchangers, radioactive material may adhere to the water chamber and the interior of the heat transfer tubes fixed to the tube sheet. On the other hand, radioactive material adheres only to the surface of the tube sheet and can therefore be easily removed. In this case, the tube sheet can be reused by removing the heat transfer tubes.

[0004] As a process for removing heat transfer tubes, a known method for dismantling a heat exchanger includes the step of removing the arc portion of the heat transfer tube; cutting the connection between the straight portion of the heat transfer tube and the tube plate, and extracting the straight portion of the heat transfer tube from the body of the heat exchanger along the direction in which the straight portion extends (see Japanese Patent Publication No. 2014-59149).

[0005] In the heat exchanger disclosed in the aforementioned publication, the heat transfer tube has an arc portion and a straight portion extending from one end of each of the arc portions, is inserted into and supported by a plurality of tube support plates, and is fixed to the body through the tube plate. According to the method of disassembling the heat exchanger disclosed in the aforementioned publication, the heat transfer tube is removed in the following process. First, the edge portion of the straight portion fixed to the tube plate and the arc portion of the heat transfer tube is cut off on the tube plate side. Only the straight portion of the heat transfer tube remaining after cutting is inserted straight into the tube support plate and supported by it, and is movable along the axial direction of the body of the heat exchanger. Then, from the side where the arc portion of the heat transfer tube was removed, the straight portion is extracted from the body along the direction in which the straight portion extends (axial direction) while maintaining its straight shape. Prior art literature

[0006] Patent Document 1: Japanese Patent Publication No. 2014-59149 The problem to be solved

[0007] According to the method of dismantling a heat exchanger disclosed in the aforementioned publication, the edge portion of the straight section of the heat transfer tube fixed to the tube plate is cut off on the tube plate side. Generally, the heat exchanger includes a plurality of heat transfer tubes; therefore, it is necessary to cut off individual heat transfer tubes, which tends to require time and effort and makes it difficult to sufficiently reduce the exposure dose during the operation.

[0008] In addition, according to the method of dismantling a heat exchanger disclosed in the aforementioned publication, the heat transfer tubes remain in the tube sheet. When the tube sheet is to be reused, it is melted in a melting furnace and processed into a product; however, when the tube sheet with the remaining heat transfer tubes is reused, if radioactive material adheres to the inner surface of the heat transfer tubes, a contaminated reused product may be provided as a result. If the tube sheet and heat transfer tubes, which are made of different materials, are directly melted, the materials may mix, and the quality of the resulting reused product may deteriorate.

[0009] The present invention has been made in consideration of the prior situation, and the objective of the present invention is to provide a method for dismantling a heat exchanger, the dismantling method having excellent workability, further reducing radiation dose, and enabling easy reuse of the tube plate as a metal material. means of solving the problem

[0010] A method for dismantling a heat exchanger according to one embodiment of the present invention is a method for dismantling a heat exchanger, wherein the heat exchanger is used in a nuclear facility and comprises a heat transfer tube; a tube plate for fixing the heat transfer tube; and a cylindrical body for accommodating the heat transfer tube and the tube plate, wherein the heat transfer tube comprises an arc portion; and a straight tube portion that is parallel to the central axis of the body and extends from one end of each of the arc portions to penetrate from the front to the rear of the tube plate, and the straight tube portion is welded to the tube plate on the rear side of the tube plate, and the dismantling method comprises a process of removing the arc portion of the heat transfer tube; a process of removing the weld portion where the straight tube portion is welded to the tube plate by slicing the tube plate, wherein the slicing is a process parallel to the surface of the tube plate; and a process of extracting the straight tube portion after the process of removing the arc portion and the process of removing the weld portion.

[0011] Depending on the method of dismantling the heat exchanger, the welded portions where straight tube sections are welded to the tube plate are removed by slicing the tube plate parallel to it. Therefore, all straight tube sections can be made movable by cutting them once, regardless of the number of heat transfer tubes. In addition, depending on the method of dismantling the heat exchanger, the straight tube sections are extracted after the welded portion removal process, so the straight tube sections are simultaneously extracted from the tube plate. Therefore, the tube plate from which the straight tube sections are extracted can be directly reused as a metal material. Accordingly, the method of dismantling the heat exchanger offers excellent workability, can further reduce radiation dose, and allows the tube plate to be easily reused as a metal material.

[0012] In the drawing process, the straight tube section is preferably drawn from the rear side of the tube sheet. The straight tube section extending from the tube sheet toward the arc section is generally relatively long. By drawing the straight tube section from the rear side of the tube sheet in this manner during the drawing process, the straight tube section is supported by the tube sheet until the end, allowing the long straight tube section to be drawn stably.

[0013] The straight tube section expands in diameter at the penetration point of the tube sheet and adheres to the tube sheet; therefore, it is desirable for the heat exchanger dismantling method to additionally include a process for treating the expanded portion of the straight tube section after the weld removal process. If the heat transfer tube is strongly adhered to the tube sheet due to tube expansion or other factors during construction, the straight tube section may not be easily extracted by removing the weld. In such cases where the straight tube section expands in diameter at the penetration point of the tube sheet and adheres to the tube sheet, the easy extraction of the straight tube section becomes possible through a heat exchanger dismantling method that additionally includes a process for treating the expanded portion of the straight tube section after the weld removal process.

[0014] The expansion portion treatment process is preferably performed by cutting the wall of the straight tube section. When the expansion portion treatment process is performed by cutting the wall of the straight tube section in this manner, the adhesive portion between the tube plate and the heat transfer tube can be reliably removed, thereby enabling easier drawing of the straight tube section.

[0015] The process of treating the expanded portion is preferably performed by relaxing the adhesive strength between the straight tube section and the tube sheet. When the process of treating the expanded portion is performed in this manner by relaxing the adhesive strength between the straight tube section and the tube sheet, the expanded portion can be removed simultaneously with the drawing of the straight tube section, thereby improving workability.

[0016] As a process to reduce adhesive strength, preferably, a portion of the wall of the straight tube section is cut in the direction of the thickness of the tube plate. When a portion of the wall of the straight tube section is cut in this way in the direction of the thickness of the tube plate, the straight tube section can be easily extracted with a relatively small amount of cutting. Accordingly, the amount of radioactive material attached and dust generated during cutting can be suppressed, thereby enabling a further reduction in the radiation dose.

[0017] As a process to reduce adhesive strength, at least the tube plate is preferably heated and cooled. When at least the tube plate is heated and cooled as a process to reduce adhesive strength in this way, the straight tube section can be extracted without cutting the heat transfer tube. Effects of the invention

[0018] As described above, the method for dismantling a heat exchanger according to the present invention offers excellent workability, can further reduce radiation dose, and allows the tube plate to be easily reused as a metal material. Brief explanation of the drawing

[0019] FIG. 1 is a flow chart illustrating a method for disassembling a heat exchanger according to one embodiment of the present invention. FIG. 2 is a schematic cross-sectional view illustrating a heat exchanger that is dismantled by the method of dismantling the heat exchanger of FIG. 1. Figure 3 is a schematic enlarged cross-sectional view of part III in Figure 2. Figure 4 is a schematic diagram illustrating the state in which the head portion of a heat exchanger is removed. Figure 5 is a schematic diagram illustrating the state in which the arc portion of a heat exchanger is removed. Figure 6 is a schematic diagram illustrating the state in which the tube plates of a heat exchanger are sliced. Figure 7 is a schematic cross-sectional view illustrating an example of the process of processing the enlarged portion by cutting. FIG. 8 is a schematic plan view illustrating an example of a process for treating an enlarged portion by relaxing the adhesive strength. Specific details for implementing the invention

[0020] Hereinafter, embodiments of the present invention are described in detail with appropriate reference to the drawings.

[0021] The method for dismantling a heat exchanger illustrated in FIG. 1 is a method for dismantling a heat exchanger, the heat exchanger is used in a nuclear facility, and includes a process for removing an arc part (S1); a process for removing a welded part (S2); a process for treating an enlarged part (S3); and a drawing process (S4).

[0022] heat exchanger

[0023] FIG. 2 illustrates the structure of a heat exchanger (1) that is dismantled by a method of dismantling a heat exchanger. The heat exchanger (1) includes a plurality of heat transfer tubes (10); a tube plate (20) that fixes the heat transfer tubes (10); and a cylindrical body (30) that accommodates the heat transfer tubes (10) and the tube plate (20).

[0024] heat transfer tube

[0025] Each heat transfer tube (10) includes an arc portion (11); and a straight tube portion (12) extending from one end of each arc portion (11) so that the straight tube portion (12) is parallel to the central axis of the body (30). As shown in FIG. 2, the position of a plurality of heat transfer tubes (10) in the body (30) is controlled by a wedge clamp (13) and a tube support plate (14). It should be noted that the heat transfer tube (10) is not fixed to the wedge clamp (13) or the tube support plate (14), and the heat transfer tube (10) is kept movable.

[0026] Official panel

[0027] The tube plate (20) is a plate for fixing the end of the straight tube section (12), and the end faces the arc section (11). The tube plate (20) is positioned at the lower end of the body (30) such that the surface of the tube plate (20) is perpendicular to the central axis of the body (30), thereby dividing the body (30) into an upper section and a lower section.

[0028] As shown in FIG. 3, each straight pipe section (12) penetrates the pipe plate (20) from the front (20a) to the rear (20b). Each straight pipe section (12) is welded to the pipe plate (20) on the rear side of the pipe plate (20) (welded section (21) in FIG. 3). Additionally, each straight pipe section (12) includes an enlarged section (12a) in which the diameter is expanded at the penetration section of the pipe plate (20), and is bonded to the pipe plate (20) by the enlarged section (12a).

[0029] body

[0030] The body (30) is divided into an upper section and a lower section by a tube plate (20), and a water chamber (31) through which a coolant is supplied and discharged is provided in the lower section. Additionally, the body (30) is configured to supply a coolant to the upper section, which is divided by the tube plate (20), so that the heat transfer tube (10) is immersed in the coolant (e.g., water).

[0031] functioning

[0032] In the heat exchanger (1), the primary coolant heated to a high temperature in the reactor is supplied to the water chamber (31). The primary coolant flows through the heat transfer tube (10), returns to the water chamber (31), and is discharged from the water chamber (31).

[0033] At this time, the area around the heat transfer tube (10) is filled with a coolant to be cooled, and heat exchange is performed using the coolant to be cooled. Accordingly, the temperature of the discharged primary coolant is reduced. The primary coolant with reduced temperature is reheated in the reactor and supplied to the water chamber (31).

[0034] Meanwhile, the coolant heated by heat exchange is extracted from the heat exchanger (1), and the thermal energy of the coolant is utilized.

[0035] As such, since the heat exchanger (1) is used in a nuclear facility, there is a possibility that radioactive material may pass through the heat transfer tube (10) and / or the water chamber (31). Therefore, it is highly likely that radioactive material is mainly contained in the heat transfer tube (10) and the water chamber (31), and is not contained in other parts or is contained in trace amounts.

[0036] Considering the above, each process of the heat exchanger dismantling method is explained below.

[0037] Arc removal process

[0038] In the arc removal process (S1), each arc (11) of the heat transfer tube (10) is removed.

[0039] Specifically, the above process is carried out as follows. First, the head portion of the heat exchanger (1) is removed by cutting with a cutter or the like. At this time, as shown in FIG. 4, the heat transfer tube (10) remains uncut. Since it is difficult for radioactive material to be exposed to the outside unless the heat transfer tube (10) is cut, sealing of the cut portion is not necessary.

[0040] Next, the arc section (11) is removed. When the arc section (11) is removed, the inner side of each heat transfer tube (10) is exposed, so radioactive material can be discharged to the outside. Therefore, the arc section (11) is removed in a dismantling room that can prevent leakage of radioactive material. It should be noted that subsequent processes are performed with the inner side of each heat transfer tube (10) exposed, and thus are performed in the dismantling room until dismantling is completed.

[0041] The arc portion (11) can be removed, for example, by a known process. For example, a portion surrounding the circumference of the arc portion (11) as part of the body (30) is removed to expose the arc portion (11), and then the arc portion (11) is cut and recovered using a cutting tool such as a cutter or laser. Since radioactive material is attached to the arc portion (11) recovered in this manner, the arc portion (11) is disposed of as radioactive material.

[0042] Accordingly, as shown in FIG. 5, the heat exchanger (1) is disassembled so that only a plurality of straight tube sections (12) are standing on the tube plate (20).

[0043] Welded part removal process

[0044] In the welding portion removal process (S2), the welding portion (21) where the straight pipe portion (12) is welded to the pipe plate (20) is removed by slicing the pipe plate (20), and the slicing is parallel to the surface of the pipe plate (20).

[0045] Specifically, for example, the cutting is performed using a blade cutter at the cutting position (C) in Fig. 3.

[0046] The cutting position (C) is not particularly limited. When the portion of the tube sheet from which the welded portion (21) is removed by slicing is reused, the frictional resistance generated during penetration by the straight tube portion (12) is reduced, so the cutting position (C) is preferably closer to the front side of the tube sheet (20).

[0047] Conversely, if the portion from which the tube plate was removed is not reused, the amount of tube plate (20) to be reused can be secured, so the cutting position (C) is preferably closer to the rear side.

[0048] It should be noted that the portion from which the pipe plate has been removed is removed along with the water chamber (31) by slicing, and as shown in FIG. 6, the pipe plate (20) from which the welded portion has been removed (hereafter, the pipe plate from which the welded portion has been removed is referred to as "pipe plate") and the straight pipe section (12) remain.

[0049] Expansion part processing process

[0050] In the expansion portion processing process (S3), each expansion portion (12a) of the straight pipe portion (12) is processed after the weld portion removal process (S2).

[0051] The straight pipe section (12) can be extracted without processing the expanded portion (12a); however, as shown in FIG. 3, when the straight pipe section (12) is strongly adhered to the pipe plate (20) of the heat transfer tube (10) due to pipe expansion during construction, the straight pipe section (12) may not be easily extracted by simply removing the welded portion (21). When the straight pipe section (12) has its diameter expanded at the penetration portion of the pipe plate (20) and adheres to the pipe plate (20) in this manner, the straight pipe section can be easily extracted by a method for dismantling a heat exchanger that additionally includes a process of processing the expanded portion (12a) of the straight pipe section (12) after the welded portion removal process (S2).

[0052] Examples of processes for treating the expanded portion (12a) include cutting, reducing adhesive strength, etc.

[0053] Cutting process

[0054] In the process of the cutting process, the expansion portion processing process (S3) is performed by cutting the wall of the straight pipe section (12).

[0055] Specifically, for example, the enlarged portion (12a) is cut away from the rear side of the tube sheet (20) using a cutting tool such as the drill (D) shown in FIG. 7. The enlarged portion (12a) can be cut away using a drill (D) having a diameter equal to or slightly larger than the outer diameter of the enlarged portion (12a). Although the drill (D) is used in FIG. 7, a grinding tool such as a reamer functions in a similar manner. It should be noted that the enlarged portion (12a) does not necessarily need to be cut away in its entirety, and the cutting can be performed within a range where the straight tube portion (12) can be easily extracted. In this case, the straight tube portion (12) remaining in the tube sheet (20) is extracted from the tube sheet (20) in a drawing process (S4).

[0056] In this way, when the expansion portion processing process (S3) is performed by cutting the wall of the straight tube section (12), the adhesive portion between the tube plate (20) and the heat transfer tube (10) can be reliably removed, thereby enabling easier drawing of the straight tube section (12).

[0057] Adhesive strength relaxation process

[0058] In this process, the expansion portion treatment process (S3) is performed by relaxing the adhesive strength between the straight pipe section (12) and the pipe plate (20). In this process, after the adhesive strength between the straight pipe section (12) and the pipe plate (20) is relaxed, the expansion portion (12a) can be removed simultaneously with the drawing of the straight pipe section (12) in the subsequent drawing process (S4). Thus, workability can be improved.

[0059] As a process to reduce adhesive strength, a portion of the wall of the straight pipe section (12) is preferably cut in the direction of the thickness of the pipe plate (20).

[0060] Specifically, as illustrated in FIG. 8, a portion of the pipe wall of the straight pipe section (12) is cut in the direction of the plate thickness of the pipe plate (20) so that the cross-section becomes C-shaped. In other words, a portion of the pipe wall of the straight pipe section (12) has a gap (S) that extends in the direction of the plate thickness of the pipe plate (20). By changing the shape of the expanded portion (12a) so that the gap (S) narrows, the diameter of the expanded portion (12a) can be reduced. Thus, the adhesive strength between the straight pipe section (12) and the pipe plate (20) can be relieved.

[0061] The gap (S) can be formed, for example, by a known slotter process. It should be noted that in the slotter process, only the wall of the straight pipe section (12) can be cut; however, as shown in FIG. 8, it is preferable to also cut a part of the pipe plate (20). By also cutting a part of the pipe plate (20), the gap (S) can be provided in a part of the wall of the straight pipe section (12).

[0062] As a process to reduce adhesive strength, if a portion of the wall of the straight tube section (12) is cut in the direction of the thickness of the tube plate (20) in this manner, the straight tube section (12) can be easily extracted with a relatively small amount of cutting. Accordingly, the amount of dust generated when radioactive material is attached and cut can be suppressed, thereby enabling a further reduction in the radiation dose.

[0063] In addition, as another process to reduce adhesive strength, at least the tube plate (20) can be heated and cooled.

[0064] In an attempt to mitigate adhesive strength by utilizing the difference in the coefficient of thermal expansion, according to this process, only the tube plate (20), or the tube plate (20) and the expanded portion (12a) are heated and cooled. In this case, heating and cooling are preferably performed quickly, and cooling is particularly preferably performed quickly. By rapidly cooling, the mitigation of adhesive strength is easily improved. Additionally, heating and cooling may be performed multiple times.

[0065] As a process to reduce adhesive strength, when at least the tube plate (20) is heated and cooled in this manner, the straight tube section (12) can be extracted without cutting the heat transfer tube (10).

[0066] drawing process

[0067] In the drawing process (S4), the straight pipe section (12) is extracted after the arc section removal process (S1), the weld section removal process (S2), and the enlarged section processing process (S3).

[0068] Specifically, a plurality of straight tube sections (12) are extracted one by one from the tube section (20). The straight tube sections (12) are supported by the tube plate (20) and the tube support plate (14), and the orientation of the straight tube sections (12) is maintained in a direction perpendicular to the tube section (20); thus, the straight tube sections (12) can be extracted relatively easily.

[0069] Here, the tube plate (20) supports the straight tube section (12) to the extent that the straight tube section (12) does not move in a direction perpendicular to the central axis; however, the tube support plate (14) does not fix the straight tube section (12) to the extent that the straight tube section (12) cannot move. Also, the straight tube section (12) is generally relatively long. When the straight tube section (12) is extracted from the front side, the straight tube section (12) is first separated from the tube plate (20). In this case, the straight tube section (12) is extracted solely through the tube support plate (14); however, since the tube support plate (14) does not fix the straight tube section (12) to the extent that the straight tube section (12) cannot move in a direction perpendicular to the central axis, the orientation of the straight tube section (12) is difficult to maintain, and the straight tube section (12) is easily caught by the tube support plate (14).

[0070] Accordingly, in the drawing process (S4), the straight tube section (12) is preferably drawn from the rear side of the tube plate (20). By drawing the straight tube section (12) from the rear side of the tube plate (20) in this way during the drawing process (S4), the straight tube section (12) is supported by the tube plate (20) until the end, thereby allowing the long straight tube section (12) to be drawn stably.

[0071] Since radioactive material is attached to the straight tube section (12) from which it is recovered, the straight tube section (12) is disposed of as radioactive material. Meanwhile, even if radioactive material is attached to the tube plate (20) from which the straight tube section (12) is extracted, the radioactive material can be easily physically removed; thus, the tube plate (20) can be directly reused as a metal material.

[0072] etc

[0073] When the portion from which the tube sheet has been removed is reused, the method for dismantling the heat exchanger preferably includes a process of additionally removing the penetration of the straight tube section (12) from the portion from which the tube sheet has been removed. The penetration of the straight tube section (12) can be removed from the portion from which the tube sheet has been removed by a process similar to the process in the expansion portion processing process (S3).

[0074] advantage

[0075] According to the method of dismantling the heat exchanger, the welded portion (21) where the straight pipe section (12) is welded to the pipe plate (20) is removed by slicing the pipe plate (20) in parallel. Thus, all straight pipe sections (12) can be moved by cutting once, regardless of the number of heat transfer tubes (10). Additionally, according to the method of dismantling the heat exchanger, since the straight pipe section (12) is extracted after the welded portion removal process (S2), the straight pipe section (12) is also simultaneously extracted from the pipe plate (20). Therefore, the pipe plate (20) from which the straight pipe section (12) is extracted can be directly reused as a metal material. Accordingly, the method of dismantling the heat exchanger has excellent workability and allows the pipe plate (20) to be easily reused as a metal material.

[0076] Other embodiments

[0077] It should be noted that the present invention is not limited to prior embodiments.

[0078] Although the above-described embodiment describes a method for dismantling a heat exchanger that includes a process for treating the expanded portion, this process is not an essential process and can be omitted, for example, when using a heat transfer tube that does not include an expanded portion.

[0079] Although the above-described embodiment describes cases where the arc removal process and the weld removal process are performed in this order, these processes may be performed in reverse order; that is, the arc removal process may be performed after the weld removal process. It should be noted that when these processes are performed in reverse order, the drawing process is performed after the arc removal process, i.e., as the final process. Industrial applicability

[0080] The method for dismantling a heat exchanger according to the present invention offers excellent workability, allows for further reduction of radiation dose, and enables the tube plates to be easily reused as metal materials. Explanation of the symbols

[0081] 1 heat exchanger 10 heat transfer tubes 11 Welfare Department 12 straight pipe section 12a Enlarged section 13 Wedge Clamp 14 pipe support plate 20 Gwanpan 20a front 20b rear 21 Welding part 30 body C cutting position D drill S gap

Claims

Claim 1 A method for dismantling a heat exchanger, wherein the heat exchanger is used in a nuclear facility and comprises: a heat transfer tube; a tube plate for fixing the heat transfer tube; and a cylindrical body that accommodates the heat transfer tube and the tube plate, wherein the heat transfer tube comprises: an arc portion; and a straight tube portion extending from one end of each of the two ends of the arc portion so as to be parallel to the central axis of the body and penetrate the tube plate from the front to the rear, wherein the straight tube portion is welded to the tube plate on the rear side of the tube plate, has an enlarged diameter at the penetration portion of the tube plate, and is adhered to the tube plate, and the method for dismantling the heat exchanger comprises: a process of removing the arc portion of the heat transfer tube; a process of removing the weld portion where the straight tube portion is welded to the tube plate by slicing the tube plate, wherein the slicing is a removal process parallel to the surface of the tube plate; a process of processing the enlarged portion of the straight tube portion; and a process of drawing out the straight tube portion after the arc portion removal process and the weld portion removal process. Claim 2 A method for dismantling a heat exchanger according to claim 1, wherein in the drawing process, the straight tube portion is extracted from the rear side of the tube plate. Claim 3 A method for dismantling a heat exchanger, wherein, in claim 1, the process of treating the expanded portion is performed by cutting the wall of the straight portion. Claim 4 A method for dismantling a heat exchanger, wherein, in claim 1, the process of treating the expanded portion is performed by relaxing the adhesive strength between the straight pipe portion and the pipe plate. Claim 5 A method for dismantling a heat exchanger according to claim 4, wherein, as a process for alleviating the adhesive strength, a portion of the wall of the straight tube section is cut in the direction of the thickness of the tube plate. Claim 6 A method for dismantling a heat exchanger according to claim 4, wherein, as a process for alleviating the adhesive strength, at least the tube plate is heated and cooled. Claim 7 delete

Images