Tube sheet with uniform thickness cladding structure, heat exchanger and tube sheet manufacturing method

Abstract

The present invention relates to the technical field of heat exchangers, and specifically to a tube sheet, a heat exchanger, and a method for manufacturing the tube sheet with a uniform thickness overlay structure. The heat exchanger includes a shell, a tube bundle, and a tube box. The tube bundle includes heat exchange tubes, tube sheets, and baffles. The tube sheet is fixed between the shell and the tube box. The heat exchange tubes are located in the shell. The ends of the heat exchange tubes pass through the tube sheet and connect to the tube box. The baffles stand in the shell to position the baffles. The tube sheet includes a plate body and an overlay layer arranged on the side of the plate body. The overlay layer includes a plurality of overlay protrusions directly formed by strip overlay welding, and the cross-sectional thickness of each overlay protrusion is uniform. The structure can simultaneously withstand high-speed erosion of high-pressure fluids and corrosion from high-temperature and high-pressure media. As the pressure-bearing structure expands and contracts, the overall structure can deform in a coordinated manner without cracking. At the same time, it has a simple structure and extends the life of the heat exchanger. The overlay tube sheet is suitable for chemical processes such as high-temperature combustion, reaction, and heat exchange.

Description

Technical Field

[0001] The present invention relates to the technical field of various high-temperature and high-pressure heat exchangers used in petroleum refining and chemical industry, coal chemical industry, fertilizer industry, and other various chemical equipment, and in particular to the technical field of hydrogenation heat exchangers or desulfurization heat exchangers that react through catalysts, and specifically to tube sheets with uniform thickness cladding structures, heat exchangers, and tube sheet manufacturing methods. Background Art

[0002] In the existing technology, the shell and tube heat exchanger, also known as the shell and tube heat exchanger or the shell and tube condenser, is the most widely used heat exchanger, which is suitable for the convection heat transfer of "liquid-liquid", "steam-steam", and "steam-liquid" heat exchange in the chemical, petroleum, pharmaceutical, food, light industry, metallurgy, coking and other industries, as well as the heat exchange and condensation processes such as steam condensation and liquid evaporation heat transfer.

[0003] A typical shell-and-tube heat exchanger in the prior art generally consists of a tube bundle, a shell, a tube box, and an outer cover. The tube bundle is the core of the shell-and-tube heat exchanger and typically consists of heat exchange tubes, support plates (or baffles), and tube sheets. Rows of high-efficiency heat exchange tubes are supported by support plates, with both ends inserted into the tube holes in the tube sheets and connected to them. This ensures a tight and strong joint, forming a tube bundle. Together with the shell and tube box, the tube bundle completes the entire system. The heat exchange tubes, acting as heat transfer elements, together with the support plates (or baffles), determine the heat transfer performance of the shell-and-tube heat exchanger. The tube box and shell determine the pressure-bearing capacity and operational safety and reliability of the shell-and-tube heat exchanger. This type of shell-and-tube heat exchanger boasts a mature manufacturing process and high safety performance, making it a key energy-consuming component in heat exchange equipment.

[0004] Considering the following purposes, it is often necessary to design reinforcement measures on the tube sheet of the heat exchanger:

[0005] First, to prevent chemical media or impurities from corroding the tube sheet.

[0006] Second, if there is intense airflow at the inlet and outlet of the heat exchanger or inside the center tube sheet, a wear-resistant layer needs to be provided on the tube sheet to prevent the airflow from eroding and wearing the tube sheet.

[0007] Third, in order to keep the medium clean, a layer of stainless steel is set on the surface of the ferrous metal.

[0008] To address corrosion and erosion caused by the medium, traditional technologies use expensive, corrosion-resistant or wear-resistant metal materials to manufacture the tubesheet. Furthermore, these specialized materials have low strength to withstand the medium's pressure, necessitating a very thick tubesheet structure. This not only increases costs but also increases the temperature difference across the tubesheet's thickness, increasing the thermal stress level during operation. Thermal expansion and deformation also compromise the seal between the tubesheet and flanges, and between the tubesheet and the heat exchange tubes. Summary of the Invention

[0009] In view of the above technical problems in the prior art, the present invention provides a tube sheet with a uniform thickness cladding structure, a heat exchanger and a tube sheet manufacturing method.

[0010] To achieve the above objectives, the present invention provides the following technical solutions:

[0011] A tube sheet with a uniform thickness surfacing structure is provided, comprising a plate body and a surfacing layer arranged on the side of the plate body, wherein the surfacing layer comprises a plurality of surfacing protrusions directly formed by strip electrode surfacing, and the cross-sectional thickness of each surfacing protrusion is uniform and equal.

[0012] Preferably, the surfacing layer is a single-layer structure; or the surfacing layer is a multi-layer structure, and the cross-sectional thickness of the surfacing protrusions of each surfacing layer is uniform and equal.

[0013] Preferably, the surfacing layer is a multi-layer structure, and adjacent surfacing layers are staggered, completely overlapped or partially cross-arranged.

[0014] Preferably, the surfacing protrusion is in the shape of any one of a spiral line, a concentric ring, and a plurality of parallel straight lines, or a combination of any of the above.

[0015] Preferably, the tube sheet is a flat plate or a curved tube sheet.

[0016] Preferably, the surfacing layer is provided on only one side of the tube sheet, or the surfacing layer is provided on both side surfaces of the tube sheet.

[0017] Preferably, the surfacing layer is a single-layer surfacing structure formed by surfacing welding with welding materials of the same material; or the surfacing layer is a multi-layer surfacing structure formed by surfacing welding with welding materials of the same material in two or more layers.

[0018] Preferably, the surfacing layer is a single-layer combined surfacing structure formed by surfacing welding of welding materials of different materials in sections; or the surfacing layer is a composite surfacing structure formed by surfacing welding of welding materials of different materials in two or more layers.

[0019] The heat exchanger includes a shell, a tube bundle and a tube box. The tube bundle includes heat exchange tubes, tube sheets and baffles. The tube sheets are fixed between the shell and the tube box. The heat exchange tubes are located in the shell. The ends of the heat exchange tubes pass through the tube sheets and connect to the tube box. The baffles stand in the shell to position the baffles. The tube sheets are the tube sheets with uniform thickness surfacing structures.

[0020] The method for manufacturing the tube sheet comprises the following steps:

[0021] Installation steps: Install the tube sheet to be cladding on the turntable at an angle, and install the stainless steel strip electrode cladding machine above the tube sheet;

[0022] Overlay welding steps: operate the turntable to rotate and drive the tube sheet to rotate around its own center. The molten steel in the overlay welding pool on the inclined surface of the tube sheet flows radially from the inner side near the center of the tube sheet to the outer side under the action of its own weight, so that the amount of molten steel from the inner side to the outer side is uniform;

[0023] Cooling step: The molten steel is cooled to form a surfacing protrusion of equal thickness.

[0024] Beneficial effects of the present invention:

[0025] The tube sheet and heat exchanger of the present invention have a uniform thickness surfacing structure, and the surfacing protrusions of the surfacing layer are directly formed by strip surfacing, and the thickness of the surfacing protrusions after forming is uniform, and there is no need to perform additional turning processing on the surfacing surface by a lathe, thereby retaining the surfacing surface layer with good corrosion resistance and wear resistance, so that it can take into account both the surfacing effect and the strength and safety of the tube sheet. The surfacing has high toughness and strong crack resistance, high plasticity and good deformation function, and can coordinately deform without cracking as the shell expands and contracts with heat, and has the function of simple structure and extended service life of the heat exchanger. The surfacing tube sheet is suitable for chemical process such as high-temperature combustion, reaction, and heat exchange.

[0026] The tubesheet manufacturing method of the present invention maintains a slightly tilted surface during fabrication. This allows the molten steel in the weld pool on the inclined surface to flow radially from the inside to the outside under its own weight, achieving a uniform flow of molten steel from the inside to the outside. After cooling, the weld overlay layer forms a weld bead structure with uniform thickness. Furthermore, the tilt of the tubesheet reduces the vertical pressure of the weld pool against the tubesheet body, preventing excessive molten pool depth and protecting the original strength of the base layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the structure of the heat exchanger in the embodiment.

[0028] Figure 2 Schematic diagram of the tube sheet in the embodiment.

[0029] Figure 3 Schematic diagram of the method for manufacturing the tube sheet in the embodiment.

[0030] Figure 4 Schematic diagram of another surfacing layer of the tube plate in the embodiment.

[0031] Figure 5 Schematic diagram of another surfacing layer of the tube plate strip in the embodiment.

[0032] Reference numerals:

[0033] Tube bundle 1, saddle 2, shell 3, tube box 4, tube sheet 5;

[0034] Plate body 51, surfacing layer 52;

[0035] Surfacing welding gun 6. DETAILED DESCRIPTION

[0036] The present invention is described in detail below with reference to specific embodiments and accompanying drawings.

[0037] The heat exchanger of this embodiment is as follows Figure 1 As shown, it includes a shell 3, a tube bundle 1 and a tube box 4. The shell 3 is supported by a saddle 2. The tube bundle 1 includes heat exchange tubes, tube sheets 5 and baffles. The tube sheets 5 are fixed between the shell 3 and the tube box 4. The heat exchange tubes are located in the shell 3. The ends of the heat exchange tubes pass through the tube sheets 5 and connect to the tube box 4. The baffles stand in the shell 3 to position the baffles. The tube sheets 5 are flat or curved tube sheets 5, combined with Figure 2 As shown, the tube sheet 5 includes a plate body 51 and a weld overlay layer 52 arranged on the side of the plate body 51. The weld overlay layer 52 includes a plurality of weld overlay protrusions directly formed by strip electrode weld overlay, and the cross-sectional thickness of each weld overlay protrusion is uniform. Compared with the prior art, the weld overlay protrusions of the weld overlay layer 52 are directly formed by strip electrode weld overlay, and the thickness of the weld overlay protrusions after forming is uniform. There is no need to turn the weld overlay surface by a lathe, thereby retaining the weld overlay surface layer with excellent corrosion resistance and wear resistance. The quality of the surface of the weld overlay layer 52 is often better than the quality of the inside of the weld overlay layer 52. If the weld overlay surface needs to be turned by a lathe after weld overlay, part of the high-quality weld overlay surface layer will be damaged in pursuit of consistent surface dimensions. It should be noted that the strip electrode weld overlay machine is directly purchased from existing equipment on the market.

[0038] In order to achieve the above-mentioned direct formation of uniform thickness surfacing protrusions by strip electrode surfacing, the manufacturing method is described in detail below:

[0039] Inventive Concept: If a rotary strip electrode overlay welder is used with the overlay surface of the tube sheet 5 horizontal during operation, only weld strips of standard width can be used, resulting in low welding efficiency. When the weld strip is wide, the rotating tangential linear speeds on the inside and outside of the strip differ, resulting in different arc lengths for the weld seam formed at the same time. However, the amount of weld strip material melted on the inside and outside during the same time is the same. This results in different weld seam thicknesses on the inside and outside. The weld seam on the inside is thicker due to its shorter arc length, while the weld seam on the outside is thinner due to its longer arc length. Therefore, after overlay welding, the overlay surface must be turned on a vertical lathe before the second overlay layer can be applied. This wastes some corrosion-resistant metal and the associated labor. Originally, the overlay surface layer is protected from further high-temperature burnout and cools and solidifies first, forming a high-quality layer with the highest corrosion and wear resistance. Unfortunately, this is removed by the surface turning process, leaving the remaining overlay layer suboptimal.

[0040] In order to solve this problem, the present invention innovatively proposes to combine Figure 3 The method shown,

[0041] The method for manufacturing the tube sheet 5 comprises the following steps:

[0042] Installation steps: install the tube sheet 5 to be cladding on the turntable at an angle, and install the cladding welding gun 6 of the stainless steel strip electrode cladding machine above the tube sheet 5;

[0043] Overlay welding steps: operate the turntable to rotate and drive the tube sheet 5 to rotate around its own center line. The molten steel in the overlay welding pool on the inclined surface of the tube sheet 5 flows radially from the inner side near the center to the outer side of the tube sheet 5 under the action of its own weight, so that the amount of molten steel from the inner side to the outer side is uniform;

[0044] Cooling step: The molten steel is cooled to form a surfacing protrusion of equal thickness.

[0045] As can be seen from the above, during the manufacture of the tube sheet 5 in this embodiment, the weld overlay surface of the tube sheet 5 is slightly tilted at an angle θ. This allows the molten steel in the weld pool on the inclined surface to flow radially from the inside to the outside under its own weight, achieving a uniform flow of molten steel from the inside to the outside. After cooling, the weld overlay layer 52 forms a weld bead structure with uniform thickness. Furthermore, the tilt of the tube sheet 5 reduces the vertical pressure of the weld pool on the tube sheet 5 body 51, preventing excessive molten pool depth and protecting the original strength of the base layer from excessive damage.

[0046] After surfacing, it is no longer necessary to use a vertical lathe to turn the surfacing surface before performing the second layer of surfacing. This avoids wasting precious metals and the associated labor, while retaining the surfacing surface layer with the best corrosion resistance and wear resistance. The surfacing layer 52 is a surfacing structure with a shallow penetration depth of the base layer. During the rotary strip surfacing operation, the surfacing surface of the tube sheet 5 is placed in an inclined state to reduce the vertical pressure of the molten steel's own weight on the surface of the tube sheet 5, avoid excessive molten pool depth, and protect the original strength of the base layer from being excessively damaged. Different surfacing structures have different construction equipment configurations, different construction efficiencies, different weld bead sizes, different weld structures, different balance and uniformity, and different residual stress distributions. The most suitable surfacing method can be selected based on the actual situation of the tube sheet 5.

[0047] like Figure 4 As shown, the surfacing protrusion is a spiral continuous weld bead, and the main body of the surfacing layer 52 only needs one arc start to complete the operation, avoiding the instability of multiple arc starts and arc ends, and ensuring the material and structural quality of the surfacing layer 52.

[0048] like Figure 5As shown, specifically, the surfacing protrusion is an intermittent weld bead formed by radially fitting annular circles. The main body of the surfacing layer 52 has good uniformity and convergent thermal deformation, which is convenient for surface processing after surfacing, avoids inconsistent thickness distribution of the surfacing layer 52 caused by uniform processing, and ensures the structural and dimensional quality of the surfacing layer 52.

[0049] like Figure 5 As shown, specifically, the surfacing protrusion is a straight intermittent weld bead parallel to the diameter direction, and each weld bead overlaps each other at the edge. Such a surfacing process is easy to operate, the welding machine moves smoothly along the straight line, and the material composition in the weld bead is relatively uniform, thereby avoiding the inconsistent thickness of the surfacing layer 52 caused by swaying during the rotation of the tube sheet 5 and the uneven distribution of tissue between the inner and outer sides of the weld bead due to different tangential linear speeds.

[0050] In practice, the surfacing layer 52 is a single-layer surfacing structure made of welding materials of the same material. Such a surfacing process does not require much change, which is convenient for improving efficiency.

[0051] Alternatively, the surfacing layer 52 is a composite surfacing structure formed by surfacing two or more layers of welding material of the same material. The surfacing forms between the layers can be different, and different combinations can affect each other, offset harmful deformation effects, and play a beneficial role.

[0052] Alternatively, the cladding layer 52 is a single-layer combined cladding structure formed by segmented cladding of welding materials of different materials. The environments to which different areas on the tube sheet 5 are subjected are different, especially in the heat exchanger after the tube has undergone multiple heat exchange processes. In the areas where the inlet and outlet of the tube box 4 are located, the physical properties of the medium change significantly due to temperature changes. The areas impacted by incoming materials need to be more wear-resistant and erosion-resistant, and the areas where the flow medium swirls also need to be resistant to cavitation. Therefore, different cladding layers 52 are required.

[0053] Alternatively, the surfacing layer 52 is a composite surfacing structure formed by surfacing two or more layers of welding materials of different materials. Generally speaking, the first layer surfacing with the plate body 51 of the tube sheet 5 needs to be fused with the base layer in a friendly manner, but also requires a shallowest penetration depth and cannot damage the base layer too much, while the surface layer in contact with the medium needs to have good corrosion resistance.

[0054] Alternatively, the cladding layer 52 may be a composite cladding structure composed of claddings of different weld bead structures, which may result in a structure with excellent overall performance. Alternatively, the cladding layer 52 may be a composite cladding structure composed of claddings of different materials and different weld bead structures, which may result in a structure with excellent overall performance.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for manufacturing a tube sheet having a uniform thickness cladding structure, characterized by: The tube sheet with a uniform thickness surfacing structure comprises a plate body and a surfacing layer provided on the side of the plate body, wherein the surfacing layer comprises a plurality of surfacing protrusions directly formed by strip electrode surfacing, and the cross-sectional thickness of each surfacing protrusion is uniform and equal; The method comprises the following steps: Installation steps: Install the tube sheet to be cladding on the turntable at an angle, and install the stainless steel strip electrode cladding machine above the tube sheet; Overlay welding steps: operate the turntable to rotate and drive the tube sheet to rotate around its own center. The molten steel in the overlay welding pool on the inclined surface of the tube sheet flows radially from the inner side near the center of the tube sheet to the outer side under the action of its own weight, so that the amount of molten steel from the inner side to the outer side is uniform; Cooling step: The molten steel is cooled to form a surfacing protrusion of equal thickness.

2. The method according to claim 1, wherein: The surfacing layer is a single-layer structure; or the surfacing layer is a multi-layer structure, and the cross-sectional thickness of the surfacing protrusions of each surfacing layer is uniform and equal.

3. The method according to claim 2, wherein: The surfacing layer is a multi-layer structure, and adjacent surfacing layers are staggered, completely overlapped or partially cross-arranged.

4. The method according to claim 1, wherein: The surfacing protrusions are in any one of a spiral shape, a concentric ring shape, and a plurality of parallel straight line shapes, or a combination of any of the above.

5. The method according to claim 1, wherein: The tube sheet is a flat plate or a curved tube sheet.

6. The method according to claim 1, wherein: The surfacing layer is provided on only one side of the tube sheet, or the surfacing layer is provided on both sides of the tube sheet.

7. The method according to claim 1, wherein: The surfacing layer is a single-layer surfacing structure formed by surfacing welding with welding materials of the same material; or the surfacing layer is a multi-layer surfacing structure formed by surfacing welding with welding materials of the same material in two or more layers.

8. The method according to claim 1, wherein: The surfacing layer is a single-layer combined surfacing structure formed by surfacing welding of welding materials of different materials in sections; or the surfacing layer is a composite surfacing structure formed by surfacing welding of welding materials of different materials in two or more layers.

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