Shell-and-tube heat exchanger assembly and method for limiting corrosion response of tubes therein

Abstract

The invention relates to a shell-and-tube heat exchanger assembly and a method for limiting corrosion response of tubes therein, and specifically discloses a shell-and-tube heat exchanger assembly including a first tube sheet, a second tube sheet, and a plenum. The first tube sheet is adapted to be secured to a shell of a shell-and-tube heat exchanger assembly. The first tube plate includes a plurality of first apertures adapted to support a plurality of tubes extending through the shell. The second tube sheet is adapted to be secured to the front surface of the first tube sheet and to the rear surface of the air chamber. The second tube sheet includes a plurality of second apertures adapted to support a plurality of tubes extending through the plurality of first apertures. The second tube sheet is made of a metal adapted to limit a corrosion response of the plurality of tubes when exposed to a cooler fluid.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 512,369, filed on July 7, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates generally to shell and tube heat exchangers. More particularly, the present disclosure relates to a shell and tube heat exchanger assembly and a method for limiting the corrosion response of tubes of the shell and tube heat exchanger assembly. Background Art

[0004] A shell and tube heat exchanger is a heat exchanger that includes a shell and bundled tubes inside the shell. When aluminum tubes are used in a steel shell, the tubes experience high galvanic corrosion pairing between dissimilar metals, and as a result, the material inside the tube wears away, thereby causing wall thinning. The main disadvantage of galvanic corrosion is that pairing can lead to accelerated corrosion and premature failure of metal parts or structures. This is because while protecting the cathode metal, the corrosion rate of the anode metal can be significantly increased. The resulting corrosion products can also cause blockages and reduce the efficiency of fluid flow in heat exchangers, pipelines and other equipment. In some cases, the wall thickness reduction exceeds the allowable limit that may cause tube leakage or rupture.

[0005] Therefore, there is a need for an improved shell and tube heat exchanger that addresses the disadvantages of galvanic corrosion for specific applications that can utilize materials having higher galvanic potentials than conventional industry accepted materials. Summary of the invention

[0006] This summary is provided to introduce a selection of concepts that are further described in the detailed description of the present disclosure in a simplified format. This summary is not intended to identify key or essential inventive concepts of the present disclosure, nor is it intended to determine the scope of the present disclosure.

[0007] A shell and tube heat exchanger assembly is disclosed herein and includes a first tube sheet, a second tube sheet, and a plenum. The first tube sheet is adapted to be secured to a shell of the shell and tube heat exchanger assembly. The first tube sheet includes a plurality of first holes adapted to support a plurality of tubes extending through the shell. The second tube sheet is adapted to be fastened to a front surface of the first tube sheet and to a rear surface of the plenum. The second tube sheet includes a plurality of second holes adapted to support a plurality of tubes extending through the plurality of first holes, such that the second tube sheet is made of a metal adapted to limit a corrosion response of the plurality of tubes when exposed to a cooler fluid.

[0008] In one or more embodiments according to the present disclosure, the electrochemical potential of the metal of the second tube sheet is equal to or lower than the electrochemical potential of the material of the plurality of tubes.

[0009] In one or more embodiments according to the present disclosure, the second tube sheet is made of at least one of an aluminum alloy and an inert material.

[0010] In one or more embodiments according to the present disclosure, each of the plurality of tubes is made of an aluminum alloy.

[0011] In one or more embodiments according to the present disclosure, the plurality of first holes of the first tube sheet are aligned with the plurality of second holes of the second tube sheet.

[0012] In one or more embodiments according to the present disclosure, a plurality of first openings are defined in the first tube sheet, a plurality of second openings are defined in the second tube sheet, and a plurality of third openings are defined in the plenum.

[0013] In one or more embodiments according to the present disclosure, each of the plurality of first openings defined in the first tube sheet is aligned with a corresponding second opening of the plurality of second openings defined in the second tube sheet and a corresponding third opening of the plurality of third openings defined in the plenum.

[0014] In one or more embodiments according to the present disclosure, a plurality of fasteners are adapted to be inserted into the aligned plurality of first openings, a plurality of second openings, and a plurality of third openings to fasten the second tube sheet to the front surface of the first tube sheet and to fasten the second tube sheet to the rear surface of the plenum.

[0015] In one or more embodiments according to the present disclosure, the plurality of fasteners include at least one of a guide pin, a threaded fastener, and a bolt fastener.

[0016] In one or more embodiments according to the present disclosure, a sealing element is disposed in each of a plurality of first holes between the plurality of tubes extending through the shell and the first tube sheet.

[0017] In one or more embodiments according to the present disclosure, the cooler fluid inside each tube of the plurality of tubes is water.

[0018] A method for limiting the corrosion response of a plurality of tubes of a shell and tube heat exchanger assembly is also disclosed. The method includes securing a first tube sheet to a shell of the shell and tube heat exchanger assembly. The step then includes disposing a second tube sheet between the first tube sheet and a plenum of the shell and tube heat exchanger assembly. The second tube sheet is secured to a front surface of the first tube sheet and a rear surface of the plenum. The second tube sheet is made of a metal suitable for limiting the corrosion response of the plurality of tubes when exposed to a cooler fluid.

[0019] In one or more embodiments according to the present disclosure, the electrochemical potential of the metal of the second tube sheet is equal to or lower than the electrochemical potential of the material of the plurality of tubes.

[0020] In one or more embodiments according to the present disclosure, the second tube sheet is made of at least one of an aluminum alloy and an inert material.

[0021] In one or more embodiments according to the present disclosure, the second tube sheet is fastened to the front surface of the first tube sheet and the rear surface of the plenum using at least one of a fastener and an industrial adhesive.

[0022] In one or more embodiments according to the present disclosure, the step of fastening the second tube sheet to the front surface of the first tube sheet and the rear surface of the air chamber further includes aligning each of the plurality of first openings defined in the first tube sheet with a corresponding second opening of the plurality of second openings defined in the second tube sheet. Then, each of the plurality of second openings is aligned with a corresponding third opening of the plurality of third openings defined in the air chamber. A plurality of fasteners are inserted into the aligned plurality of first openings, the plurality of second openings, and the plurality of third openings to fasten the second tube sheet to the front surface of the first tube sheet and to fasten the second tube sheet to the rear surface of the air chamber.

[0023] In order to further illustrate the advantages and features of the method and system, a more specific description of the method and system will be presented by reference to its specific embodiments shown in the accompanying drawings. It is understood that these drawings only depict typical embodiments of the present disclosure and therefore should not be considered to limit its scope. The present disclosure will be described and explained with additional specificity and detail using the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] These and other features, aspects and advantages will become better understood when the following detailed description is read with reference to the accompanying drawings, in which like characters represent like parts throughout, and in which:

[0025] Figure 1A exemplarily illustrating an assembly view of a shell and tube heat exchanger assembly;

[0026] Figure 1B Exemplary illustration Figure 1A an enlarged view of a cover assembly of a shell and tube heat exchanger assembly shown in;

[0027] Figure 1C Schematically illustrates a sectional isometric view of the cover assembly about the axis AA';

[0028] Figure 1D exemplarily illustrating a cross-sectional view of the cover assembly about the axis AA';

[0029] Figure 2 illustratively illustrating an exploded view of a shell and tube heat exchanger assembly; and

[0030] Figure 3 A flow chart indicating a method for limiting the corrosion response of a plurality of tubes of a shell and tube heat exchanger assembly is exemplarily illustrated.

[0031] Furthermore, those skilled in the art will appreciate that the elements in the drawings are illustrated for simplicity and may not necessarily be drawn to scale. For example, a flow chart illustrates the method in terms of the most salient steps involved to help improve understanding of aspects of the present disclosure. Furthermore, with respect to the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details relevant to understanding the embodiments of the present disclosure so as not to obscure the drawings with details that would be readily apparent to one of ordinary skill in the art having the benefit of the description herein. DETAILED DESCRIPTION

[0032] To promote an understanding of the principles of the present disclosure, reference will now be made to various embodiments and specific language will be used to describe them. It will be understood, however, that this is not intended to limit the scope of the present disclosure, and such changes and further modifications in the illustrated systems, and such further applications of the principles of the present disclosure as shown therein are considered to be normally thought of by those skilled in the art to which the present disclosure relates.

[0033] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are illustrative of the present disclosure and are not intended to limit the present disclosure.

[0034] References throughout this specification to "one aspect," "another aspect," or similar language mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrases "in one embodiment," "in another embodiment," "some embodiments," "one or more embodiments," and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

[0035] The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process or method that includes a list of steps includes not only those steps, but may also include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or subsystems or elements or structures or parts beginning with "comprising ... one" do not exclude the presence of other devices or other subsystems or other elements or other structures or other parts or additional devices or additional subsystems or additional elements or additional structures or additional parts, without further constraints.

[0036] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0037] Galvanic corrosion pairing between dissimilar metals is a type of corrosion that occurs when two different metals come into contact with each other in the presence of an electrolyte, such as water or a corrosive fluid. In this case, the more electronegative metal becomes the anode and corrodes preferentially, while the more electropositive metal becomes the cathode and corrodes less or not at all.

[0038] In the case of heat exchangers, galvanic corrosion between dissimilar metal pairs can be particularly problematic because they often use a combination of different metal alloys, such as copper, brass, stainless steel, aluminum, and titanium. These alloys can have different electrochemical potentials, and if they come into contact with each other, galvanic corrosion can occur. This can lead to leaks, reduced heat transfer efficiency, and expensive maintenance or replacement of the heat exchanger.

[0039] Figure 1A An assembled view of the shell and tube heat exchanger assembly 100 is exemplarily illustrated.

[0040] The shell and tube heat exchanger assembly 100 may include a cover assembly 101 and a shell 103 of a can-shaped container similar to a large I letter and a plurality of tubes bundled inside the shell 103. In an embodiment, the tube may be made of aluminum metal or an aluminum alloy. Hereinafter, without departing from the scope of the present disclosure, the tube may be used to represent an aluminum tube or an aluminum alloy tube. The shell 103 may have a plurality of ports for supplying fluids in the shell and tube heat exchanger. The plurality of ports may include an upstream supply port for supplying fluids in the shell 103 and the tubes, respectively. For example, the fluid flowing through the tube may be cooler water, and the fluid in the shell 103 may be a refrigerant. Therefore, the upstream supply port may supply cooler water to the tube and refrigerant to the shell 103, respectively. Similarly, one or more exhaust ports may be provided to remove exhaust steam formed in the shell 103 during the heat transfer cycle of the shell and tube heat exchanger assembly 100.

[0041] The shell and tube heat exchanger assembly 100 can be designed to allow one or more fluids (such as a first fluid and a second fluid having different starting temperatures) to flow therethrough. In an embodiment, the first fluid may be a cooler fluid, such as water, and the second fluid may be a refrigerant. The first fluid may flow through the tube (tube side), and the second fluid may flow in the shell 103 (shell side) but outside the tube. Heat is transferred between the fluids passing through the tubes, or from the tube side to the shell 103 side, or vice versa. The fluid may be a liquid or gas on the shell 103 or tube side. Several tubes are bundled together in the shell 103 of the shell and tube heat exchanger assembly 100 to increase the heat transfer area. In an embodiment, the tubes are coaxially arranged inside the shell 103 to effectively transfer heat in the cylindrical can-shaped shell 103.

[0042] Figure 1B Exemplary illustration Figure 1AAn enlarged view of the cover assembly 101 of the shell and tube heat exchanger assembly 100 is shown in FIG. Figure 1C A cross-sectional isometric view of the cover assembly 101 about the axis AA′ is exemplarily illustrated. Figure 1D The cross-sectional view of the cover assembly 101 about the axis A-A' is exemplarily illustrated. The shell and tube heat exchanger assembly 100 may include a first tube sheet 102, a second tube sheet 104 and a plenum 105. In an embodiment, the first tube sheet 102 has a solid cubic geometry. In addition, the plenum 105 and the second tube sheet 104 may have a solid cylindrical geometry. The first tube sheet 102 is adapted to be fixed to the shell 103 of the shell and tube heat exchanger assembly 100.

[0043] Figure 2 An exploded view of a shell and tube heat exchanger assembly 100 is shown. In an embodiment, a first tube sheet 102 includes a plurality of first holes 102a adapted to support a plurality of tubes extending through a shell 103. A second tube sheet 104 is adapted to be fastened to a front surface of the first tube sheet 102 and to a rear surface of a plenum 105. The second tube sheet 104 includes a plurality of second holes 104a adapted to support a plurality of tubes extending through the plurality of first holes 102a. The plurality of first holes 102a of the first tube sheet 102 are aligned with the plurality of second holes 104a of the second tube sheet 104.

[0044] The second tube sheet 104 is made of a metal suitable for limiting the corrosion response of the plurality of tubes when exposed to the cooler fluid. Therefore, the electrochemical potential of the metal of the second tube sheet 104 is equal to or lower than the electrochemical potential of the material of the plurality of tubes. In an embodiment, the second tube sheet 104 is made of an aluminum alloy or an inert material or both thereof. The inert material may also include plastic. Each of the plurality of tubes may be made of an aluminum alloy. It is understood that the metal of the second tube sheet 104 and the metal of the plurality of tubes may be dissimilar or different. In this case, the only condition for selecting the metal is that the electrochemical potential of the metal of the second tube sheet 104 is equal to or lower than the electrochemical potential of the material of the plurality of tubes. In an embodiment, a sealing element may be provided in each of the plurality of first holes 102a extending through the plurality of tubes of the shell 103 and the first tube sheet 102.

[0045] A plurality of first openings 102b are defined in the first tube sheet 102, a plurality of second openings 104b are defined in the second tube sheet 104, and a plurality of third openings 105a are defined in the plenum 105. In an embodiment, the plurality of second openings 104b and the plurality of third openings 105a are defined near the peripheries of the second tube sheet 104 and the plenum 105, respectively. Although the first tube sheet 102 has a solid cubic geometric configuration, the plurality of first openings 102b are defined in the first tube sheet 102 such that during assembly, the plurality of first openings 102b, the plurality of second openings 104b, and the plurality of third openings 105a are aligned. This means that each of the plurality of first openings 102b defined in the first tube sheet 102 is aligned with a corresponding second opening of the plurality of second openings 104b defined in the second tube sheet 104 and a corresponding third opening of the plurality of third openings 105a defined in the plenum 105.

[0046] The plurality of fasteners 106, 106' may be inserted into the aligned plurality of first openings 102b, the plurality of second openings 104b, and the plurality of third openings 105a. The inserted plurality of fasteners 106, 106' ensures that the second tube sheet 104 is fastened to the front surface of the first tube sheet 102. Similarly, the inserted plurality of fasteners 106, 106' ensures that the second tube sheet 104 is fastened to the rear surface of the plenum 105. In an embodiment, the plurality of fasteners 106, 106' may include, but are not limited to, at least one of a guide pin, a threaded fastener, and a bolt fastener.

[0047] The shell and tube heat exchanger assembly 100 may include a plurality of plenums 105 (sometimes referred to as water boxes). The shell and tube heat exchanger assembly 100 may also include a first cover assembly 101' and a second cover assembly 101" at opposite ends of the shell 103. The first cover assembly 101' includes a first plenum 105' and the second cover assembly 101" includes a second plenum 105" (not shown). Respectively, the second plenum 105" may be an upstream plenum and the first plenum 105' may be a downstream plenum. Although Figure 1A Only one side of the shell and tube heat exchanger assembly 100 is shown, but it must be understood that the shell and tube heat exchanger assembly 100 includes two sets of cover assemblies 101', 101" (not shown) on opposite ends of the shell 103. The two sets of cover assemblies 101', 101" include two sets of first tube sheets 102, two sets of second tube sheets 104, and first and second air chambers (105', 105"). Each of the two sets of first tube sheets 102, each of the two sets of second tube sheets 104, and the first and second air chambers (105', 105") are disposed on opposite ends of the shell and tube heat exchanger assembly 100.

[0048] Figure 3 A flow chart is illustratively shown indicating a method 300 for limiting the corrosion response of a plurality of tubes of a shell and tube heat exchanger assembly 100. For the sake of brevity, Figure 1A to Figure 2 The details of the present disclosure are explained in the description of Figure 3 There is no explanation in the description.

[0049] At step 301, the first tube sheet 102 is secured to the shell 103 of the shell and tube heat exchanger assembly 100. In an embodiment, the first tube sheet 102 has a solid cubic geometry and the shell 103 has a hollow cylindrical geometry.

[0050] In step 302, the second tube sheet 104 is disposed between the first tube sheet 102 and the air chamber 105 of the shell and tube heat exchanger assembly 100, so that the second tube sheet 104 is fastened to the front surface of the first tube sheet 102 and the rear surface of the air chamber 105. In addition, the second tube sheet 104 is made of a metal suitable for limiting the corrosion response of the plurality of tubes when exposed to the cooler fluid. In an embodiment, the second tube sheet 104 is made of an aluminum alloy or an inert material or a combination of the two. The inert material may also include plastic. In an embodiment, the second tube sheet 104 is fastened to the front surface of the first tube sheet 102 and the rear surface of the air chamber 105 using at least one of fasteners 106, 106' and industrial adhesives.

[0051] During assembly, the step of fastening the second tube sheet 104 to the front surface of the first tube sheet 102 and the rear surface of the air chamber 105 further includes aligning each of the plurality of first openings 102b defined in the first tube sheet 102 with a corresponding second opening in the plurality of second openings 104b defined in the second tube sheet 104. Then, each of the plurality of second openings 104b is aligned with a corresponding third opening in the plurality of third openings 105a defined in the air chamber 105. Finally, a plurality of fasteners 106, 106' are inserted into the aligned plurality of first openings 102b, the plurality of second openings 104b, and the plurality of third openings 105a to fasten the second tube sheet 104 to the front surface of the first tube sheet 102 and to fasten the second tube sheet 104 to the rear surface of the air chamber 105.

[0052] For water-cooled chillers, replacing existing copper tubes with aluminum tubes has significant cost savings potential. The aluminum tubes are rolled in place at the first tube sheet 102 to provide a tight seal. If the aluminum tubes are inserted into the first tube sheet 102 made of steel, when exposed to the cooler fluid (such as water), if no countermeasures are taken, the aluminum tubes will corrode. Advantageously, the provision of the second tube sheet 104 made of an aluminum alloy limits the corrosion response of the plurality of aluminum tubes when exposed to the cooler fluid (such as water).

[0053] In addition, the design of the second tube sheet 104 includes a plurality of second holes 104a that match the design of the plurality of first holes 102a defined in the first tube sheet 102. The design maintains the structural design of the current shell and tube heat exchanger assembly 100 unchanged with minimal changes. This eliminates the need for lengthy or extensive structural testing processes to prove that the design can withstand operational thermomechanical loads, shipping loads, installation, and overall field use. Since the structure of the shell and tube heat exchanger assembly 100 has minimal changes, the solution can be a factory installed option, or even a field retrofit with minor modifications.

[0054] It will be apparent to those skilled in the art that various working modifications may be made to this method in order to implement the inventive concepts as taught herein.

[0055] In addition, the actions of any flow chart do not need to be implemented in the order shown; not all actions need to be performed. In addition, those actions that do not depend on other actions can be performed in parallel with other actions.

[0056] The accompanying drawings and the foregoing description give examples of embodiments. It will be appreciated by those skilled in the art that one or more of the elements described may be well combined into a single functional element. Alternatively, some elements may be divided into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, the order of the processes described herein may be changed and are not limited to the methods described herein.

[0057] The benefits, other advantages and solutions to problems have been described above with respect to specific embodiments. However, the benefits, advantages, solutions to problems, and any (multiple) components that may cause any benefit, advantage or solution to occur or become more obvious should not be construed as key or essential features or components of any or all claims.

Claims

1. A shell and tube heat exchanger assembly, comprising: A first tube sheet adapted to be fixed to a shell of the shell and tube heat exchanger assembly, the first tube sheet comprising: a plurality of first holes adapted to support a plurality of tubes extending through the shell; and a second tube sheet adapted to be fastened to a front surface of the first tube sheet and to a rear surface of the plenum, the second tube sheet comprising: a plurality of second holes adapted to support the plurality of tubes extending through the plurality of first holes, Wherein, the second tube sheet is made of a metal suitable for limiting the corrosion response of the plurality of tubes when exposed to a cooler fluid.

2. The shell and tube heat exchanger assembly according to claim 1, wherein: The electrochemical potential of the metal of the second tube sheet is equal to or lower than the electrochemical potential of the material of the plurality of tubes.

3. The shell and tube heat exchanger assembly according to claim 1, wherein: The second tube sheet is made of at least one of an aluminum alloy and an inert material.

4. The shell and tube heat exchanger assembly according to claim 1, wherein: Each of the plurality of tubes is made of an aluminum alloy.

5. The shell and tube heat exchanger assembly according to claim 1, wherein: The first plurality of holes of the first tube sheet are aligned with the second plurality of holes of the second tube sheet.

6. The shell and tube heat exchanger assembly according to claim 1, wherein: A first plurality of openings are defined in the first tube sheet, a second plurality of openings are defined in the second tube sheet, and a third plurality of openings are defined in the plenum.

7. The shell and tube heat exchanger assembly according to claim 1, wherein: Each of the plurality of first openings defined in the first tube sheet is aligned with a corresponding second opening of the plurality of second openings defined in the second tube sheet and a corresponding third opening of the plurality of third openings defined in the plenum.

8. The shell and tube heat exchanger assembly according to claim 1, wherein: A plurality of fasteners are adapted to be inserted into the aligned plurality of first openings, plurality of second openings, and plurality of third openings to fasten the second tube sheet to the front surface of the first tube sheet and to fasten the second tube sheet to the rear surface of the plenum.

9. The shell and tube heat exchanger assembly according to claim 8, wherein: The plurality of fasteners include at least one of a guide pin, a threaded fastener, and a bolt fastener.

10. The shell and tube heat exchanger assembly according to claim 1, wherein: A sealing element is disposed in each of the plurality of first holes between the plurality of tubes extending through the shell and the first tube sheet.

11. The shell and tube heat exchanger assembly according to claim 1, wherein: The cooler fluid inside each tube of the plurality of tubes is water.

12. A method for limiting the corrosion response of a plurality of tubes of a shell and tube heat exchanger assembly, the method comprising: securing a first tube sheet to a shell of the shell and tube heat exchanger assembly; The second tube sheet is disposed between the first tube sheet and the air chamber of the shell and tube heat exchanger assembly. wherein the second tube sheet is fastened to the front surface of the first tube sheet and the rear surface of the air chamber, Wherein, the second tube sheet is made of a metal suitable for limiting the corrosion response of the plurality of tubes when exposed to a cooler fluid.

13. The method according to claim 12, wherein: The electrochemical potential of the metal of the second tube sheet is equal to or lower than the electrochemical potential of the material of the plurality of tubes.

14. The method according to claim 12, wherein: The second tube sheet is made of at least one of an aluminum alloy and an inert material.

15. The method according to claim 12, wherein: The second tube sheet is fastened to the front surface of the first tube sheet and the rear surface of the plenum using at least one of fasteners and industrial adhesives.

16. The method according to claim 12, wherein: The step of fastening the second tube sheet to the front surface of the first tube sheet and the rear surface of the air chamber further includes: aligning each of a plurality of first openings defined in the first tube sheet with a corresponding second opening of a plurality of second openings defined in the second tube sheet; aligning each of the plurality of second openings with a corresponding third opening of a plurality of third openings defined in the plenum; and A plurality of fasteners are inserted into the aligned plurality of first openings, the plurality of second openings, and the plurality of third openings to fasten the second tube sheet to the front surface of the first tube sheet and to fasten the second tube sheet to the rear surface of the plenum.

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