Non-metal expansion joint of tube plate type waste gas boiler

Abstract

The invention relates to the technical field of mechanical expansion joints, in particular to a tube plate type exhaust boiler nonmetal expansion joint which comprises a multi-layer composite expansion element, a heat preservation layer and a multi-layer sealing structure, the expansion element is wrapped by the heat preservation layer, and the heat preservation layer is wrapped by the multi-layer sealing structure. The expansion element, the heat preservation layer and the multi-layer sealing structure are detachably connected through connecting pieces. The expansion joint has the following effects that modular assembly and maintenance of all structures are achieved, the axial and radial deformation compensation capacity of the expansion joint is guaranteed, multiple thermal insulation sealing protection is formed through hierarchical coating, thermal displacement stress and pressure fluctuation caused by a flue gas medium are effectively offset, the thermal stress and expansion difference of a pipe plate and a pipeline are reduced, and the service life of the pipe plate and the pipeline is prolonged. The crater cracking risk is reduced, and long-term stable operation of the waste gas boiler is guaranteed.

Description

Technical Field

[0001] This application relates to the technical field of mechanical expansion joints, and in particular to a non-metallic expansion joint for a tube sheet type waste gas boiler. Background Technology

[0002] In industrial production, tube sheet type waste gas boilers are a common and important type of equipment, widely used in many fields such as chemical industry and power generation. The design and manufacture of expansion joints for tube sheet type waste gas boilers typically employs a single-layer expansion element structure.

[0003] The sealing structure of a single-layer expansion element is simple and cannot guarantee a stable seal during boiler operation, making it prone to leakage. This not only affects the normal operation of the boiler but may also cause environmental pollution. Moreover, the insulation layer of a single-layer expansion element is loose, which will generate a reverse thrust during thermal displacement, leading to stress concentration. This, in turn, increases the thermal stress and expansion difference between the tube sheet and the pipeline, increasing safety hazards such as weld cracking and affecting the long-term stable operation of the boiler. Summary of the Invention

[0004] In order to reduce the thermal stress and expansion difference between the tube sheet and the pipeline, reduce the risk of weld cracking, and ensure the long-term stable operation of the waste gas boiler, this application provides a tube sheet type non-metallic expansion joint for waste gas boilers.

[0005] This application provides a tube sheet type non-metallic expansion joint for waste gas boilers, which adopts the following technical solution: it includes a multi-layer composite expansion element, a heat insulation layer, and a multi-layer sealing structure. The heat insulation layer is wrapped around the expansion element, and the multi-layer sealing structure is wrapped around the heat insulation layer. The expansion element, the heat insulation layer, and the multi-layer sealing structure are detachably connected by connectors.

[0006] By adopting the above technical solutions, modular assembly and maintenance of each structure can be achieved, which not only ensures the axial and radial deformation compensation capability of the expansion joint, but also forms multiple thermal insulation and sealing protection through layered wrapping, effectively offsetting the thermal displacement stress and pressure fluctuations caused by the flue gas medium, reducing the thermal stress and expansion difference between the tube sheet and the pipeline, reducing the risk of weld cracking, and ensuring the long-term stable operation of the waste gas boiler.

[0007] Preferably, the expansion element comprises acid and alkali resistant glass fiber coated with fluoropolymer, high-temperature elastic alloy wire mesh, and high-temperature resistant and corrosion-resistant non-metallic sealing material, wherein the acid and alkali resistant glass fiber coated with fluoropolymer, the high-temperature elastic alloy wire mesh, and the high-temperature resistant and corrosion-resistant non-metallic sealing material are arranged concentrically from the outside to the inside.

[0008] By adopting the above technical solution, acid and alkali resistant glass fiber coated with fluoropolymer cloth, high-temperature elastic alloy wire mesh, and high-temperature resistant and corrosion-resistant non-metallic sealing material are arranged concentrically from the outside to the inside along the radial direction of the expansion element. The outer layer of acid and alkali resistant glass fiber coated with fluoropolymer cloth can resist the corrosion of acid and alkali media in flue gas, the middle layer of high-temperature elastic alloy wire mesh strengthens the structural support and anti-deformation ability, and the inner layer of high-temperature resistant and corrosion-resistant non-metallic sealing material improves the media barrier effect. The gradient composite design of the three-layer structure gives the expansion element multiple properties such as corrosion resistance, deformation resistance, and sealing, delaying material fatigue under thermal cycling and extending the service life of the expansion element.

[0009] Preferably, the high-temperature elastic alloy wire mesh is embedded in the matrix of the high-temperature resistant and corrosion-resistant non-metallic sealing material in a three-dimensional braided structure, and the matrix of the high-temperature resistant and corrosion-resistant non-metallic sealing material forms a prestress compensation structure with the inner wall surface of the expansion element through an epoxy resin impregnation process.

[0010] By adopting the above technical solution, the high-temperature elastic alloy wire mesh with a three-dimensional braided structure is embedded in the matrix of the high-temperature resistant and corrosion-resistant non-metallic sealing material, which greatly improves the structural stability and deformation resistance of the sealing layer. Combined with the prestress compensation structure formed by the epoxy resin impregnation process, it can accurately offset the thermal displacement stress generated by the expansion joint in the flue gas hot and cold cycle, achieve a dynamic sealing effect, effectively disperse stress concentration, delay the fatigue deterioration of the sealing material, ensure that the sealing performance does not decline in the long term, and improve the sealing reliability of the expansion joint under complex working conditions.

[0011] Preferably, the insulation layer is provided with at least one layer, and multiple layers of insulation layers are arranged in concentric rings and sequentially wrapped around the expansion element. The multiple layers of insulation layers are pressed and sewn together to form an anisotropic thermal conductive layer.

[0012] By adopting the above technical solution, the insulation layer wraps the expansion element in a concentric ring form in multiple layers and is formed by pressing and sewing to form an anisotropic heat-conducting layer. This not only retains the axial flexibility of the expansion joint to meet the axial and radial displacement compensation requirements under flue gas conditions, but also strengthens the radial sealing strength. By utilizing the synergistic deformation characteristics of fiber materials, it avoids the generation of reverse thrust during thermal displacement, effectively offsetting the stress concentration caused by the start-up and shutdown of the waste gas boiler and the fluctuation of medium pressure, reducing heat loss while stabilizing the expansion difference between the tube sheet and the pipeline.

[0013] Preferably, each insulation layer comprises ceramic fiber cloth and high-purity zirconium aluminum-containing cotton, wherein the ceramic fiber cloth covers the high-purity zirconium aluminum-containing cotton, and the ceramic fiber cloth and the high-purity zirconium aluminum-containing cotton are composite molded together.

[0014] By adopting the above technical solution, each insulation layer is made of ceramic fiber cloth wrapped with high-purity zirconium aluminum-containing cotton. The ceramic fiber cloth provides structural protection for the insulation layer and prevents the high-purity zirconium aluminum-containing cotton from loosening and falling off. The high-purity zirconium aluminum-containing cotton exerts excellent high-temperature insulation performance. The composite molding of the two and the elimination of separate filling of rolled cotton allow the insulation layer to have both structural integrity and high-efficiency insulation. It can withstand the normal flue gas temperature of 540℃ and the extreme flue gas temperature of 640℃ of the exhaust gas boiler, effectively blocking heat transfer and reducing the risk of overheating of the external metal structure.

[0015] Preferably, the structure further includes a metal frame and side pads, wherein the metal frame is disposed on the outside of the multi-layer sealing structure, the side pads are fixed to the inner wall of the metal frame by a first bolt, and the multi-layer insulation layer is disposed on the inner side of the side pads.

[0016] By adopting the above technical solution, a metal frame is set on the outside of the multi-layer sealing structure, and the side pads are fixed on the inside by the first bolt and the heat insulation layer is set on the inside of the side pads. The side pads can block the high-temperature flue gas from directly scouring the metal frame, which greatly reduces the risk and probability of the metal frame overheating. Moreover, the side pads and the metal frame move synchronously to adapt to the thermal displacement deformation of the expansion joint. The metal frame provides external structural support for the entire expansion joint and forms a synergistic protection with the side pads and the heat insulation layer, thereby improving the stability and high temperature resistance of the overall structure of the expansion joint.

[0017] Preferably, the multilayer sealing structure includes a polytetrafluoroethylene (PTFE) film and a high-strength impregnated fiberglass cloth, wherein the PTFE film forms a composite layer with the high-strength impregnated fiberglass cloth layers on the inner and outer sides of the PTFE film through a hot-pressing process.

[0018] By adopting the above technical solution, a composite sealing layer is formed by hot pressing a polytetrafluoroethylene (PTFE) film and inner and outer high-strength impregnated fiberglass cloth. The PTFE film gives the multi-layer sealing structure excellent sealing wear resistance and high temperature resistance, while the inner and outer high-strength impregnated fiberglass cloth strengthens the structural strength and tensile strength of the sealing layer. The hot pressing process ensures the integrity of the composite layer, allowing the multi-layer sealing structure to maintain stable dynamic sealing and pressure bearing capacity during the start-up and shutdown of the waste gas boiler and the hot and cold cycles of the expansion joint, thus avoiding loosening and curling failure of the sealing layer.

[0019] Preferably, the connector includes a second bolt and a stud. The two ends of the acid and alkali resistant glass fiber coated with fluoropolymer, the high-temperature elastic alloy wire mesh and the high-temperature resistant and corrosion-resistant non-metallic sealing material are respectively fixed by the second bolt, and the multiple layers of the insulation layer are fixed by the stud.

[0020] By adopting the above technical solution, the two ends of the three-layer composite structure of the expansion element are fixed by the second bolt, ensuring the connection of the expansion element itself and preventing interlayer separation under thermal cycling and media impact. At the same time, the multi-layer insulation layer is fixed separately by studs, realizing the precise fixation of the insulation layer and the expansion element, avoiding radial slippage and bulging of the insulation layer during thermal displacement. The differentiated detachable design of the second bolt and studs not only ensures the fixation reliability of each structure, but also facilitates later inspection and replacement, adapting to the on-site maintenance needs of the waste gas boiler.

[0021] Preferably, a medium channel for medium flow is formed inside the expansion element, and an inner liner is also provided inside the expansion element. One end of the inner liner is fixed to the expansion element by the second bolt, and the other end of the inner liner is suspended in the medium channel.

[0022] By adopting the above technical solution, an inner liner is installed in the medium channel of the expansion element. One end is fixed to the expansion element by a second bolt, and the other end is suspended. This design allows the inner liner to directly resist the scouring and corrosion of high-temperature flue gas, protect the main structure of the expansion element, and reduce wear and thermal damage caused by direct scouring of the medium. Since the suspended end has no fixed constraint, it can adapt to the thermal displacement deformation of the expansion joint, avoid the inner liner from generating additional stress due to deformation, and at the same time, it does not affect the normal flow of flue gas, thus taking into account both protection and the deformation compensation capability of the expansion joint.

[0023] In summary, this application includes at least one of the following beneficial technical effects: 1. By synergistically enhancing the media barrier capability through chemical bonding and physical cross-linking, and utilizing the pre-stress compensation mechanism to offset thermal displacement stress, dynamic sealing is achieved. During the thermal cycling process of the expansion joint, fatigue damage can be effectively delayed, and the service life of the sealing structure and expansion element can be extended simultaneously. 2. It maintains axial flexibility while enhancing radial sealing strength. By utilizing the synergistic deformation characteristics of the fiber insulation material itself, it ensures that no reverse thrust is generated during thermal displacement, offsets stress concentration caused by start-up and shutdown of the waste gas furnace, fluctuations in medium pressure, and changes in operating conditions, reduces thermal stress and expansion difference between the tube sheet and the pipeline, eliminates hidden dangers such as weld cracking, and achieves long-term stability of the absorption expansion and boiler mechanical properties. 3. The expansion joint adopts a multi-layer sealing and thermal insulation design. The inner front sealing layer provides initial thermal insulation. From the inside out, it is integrally formed by ceramic fiber covering high-purity high-alumina cotton to achieve a stepped thermal insulation effect. High-strength impregnated fiberglass cloth is arranged on both the inner and outer sides of the polytetrafluoroethylene film to protect and enhance the polytetrafluoroethylene film to form a dynamic sealing interface, maintaining stable sealing and pressure bearing capacity during the start-up and shutdown of the waste gas boiler and the hot and cold cycles of the expansion joint. Attached Figure Description

[0024] Figure 1This is a cross-sectional view of the overall structure of this application; Figure 2 yes Figure 1 A magnified view of part A in the diagram.

[0025] Explanation of reference numerals in the attached drawings: 110, Expansion element; 111, Acid and alkali resistant glass fiber coated with fluoropolymer cloth; 112, High-temperature elastic alloy wire mesh; 113, High-temperature resistant and corrosion-resistant non-metallic sealing material; 114, Medium channel; 115, Inner lining plate; 120, Insulation layer; 121, Ceramic fiber cloth; 122, High-purity zirconium aluminum-containing cotton; 130, Multi-layer sealing structure; 131, Polytetrafluoroethylene film; 132, High-strength impregnated glass fiber cloth; 140, Connector; 141, Second bolt; 142, Stud; 150, Metal frame; 151, Side pad; 152, First bolt. Detailed Implementation

[0026] The present application will be further described in detail below with reference to the accompanying drawings.

[0027] This application discloses a non-metallic expansion joint for tube sheet type waste gas boilers, which is used to reduce thermal stress and expansion difference between tube sheet and pipeline, reduce the risk of weld cracking, and ensure long-term stable operation of waste gas boilers.

[0028] refer to Figure 1 and Figure 2 A non-metallic expansion joint for a tube sheet type waste gas boiler includes a multi-layer composite expansion element 110, an insulation layer 120, and a multi-layer sealing structure 130. The insulation layer 120 completely wraps around the outer wall of the expansion element 110, and the multi-layer sealing structure 130 covers the outer wall of the insulation layer 120. The expansion element 110, the insulation layer 120, and the multi-layer sealing structure 130 are detachably connected by a connector 140. Each structure is independently formed and works in concert to effectively offset the thermal displacement stress and pressure fluctuations caused by the flue gas medium, reduce the thermal stress and expansion difference between the tube sheet and the pipeline, reduce the risk of weld cracking, and ensure the long-term stable operation of the waste gas boiler. It also facilitates subsequent assembly, maintenance, and component replacement. In addition, it includes a metal frame 150 and side pads 151. A medium channel 114 for medium flow is formed inside the expansion element 110, and an inner lining plate 115 is also provided inside the expansion element 110, forming an integrated protection system with the core structure to meet the operating conditions of high-temperature flue gas in the waste gas boiler.

[0029] The expansion element 110 adopts a gradient multi-layer composite structure design, including acid and alkali resistant glass fiber coated with fluoropolymer cloth 111, high temperature elastic alloy wire mesh 112, and high temperature resistant corrosion-resistant non-metallic sealing material 113. From the outside to the inside, the three layers are arranged in a concentric circle and coaxially, forming a tightly fitted cylindrical structure. The layers are fixed through a synergistic method of chemical bonding and physical cross-linking, eliminating the risk of interlayer separation. This allows the expansion element 110 to simultaneously possess multiple properties such as resistance to media corrosion, structural deformation resistance, and efficient media barrier.

[0030] Among them, the high-temperature elastic alloy wire mesh 112 is embedded in the matrix of the high-temperature corrosion resistant non-metallic sealing material 113 in a three-dimensional woven structure, so that the matrix of the sealing material forms a composite structure with a skeleton, which greatly improves the structural stability and tensile and deformation resistance of the high-temperature corrosion resistant non-metallic sealing material 113; the matrix of the high-temperature corrosion resistant non-metallic sealing material 113 and the inner wall of the expansion element 110 are treated by epoxy resin impregnation process. After curing, the two form a pre-stress compensation structure. This structure can accurately offset the thermal displacement stress generated by the expansion joint during the flue gas hot and cold cycle, realize the dynamic sealing effect of the expansion element 110, effectively disperse stress concentration, and delay the fatigue deterioration of the sealing material.

[0031] The insulation layer 120 is disposed on the outside of the expansion element 110. At least one layer can be disposed according to the operating conditions of the waste gas boiler. The multiple insulation layers 120 are nested and wrapped in concentric rings along the radial direction of the expansion element 110. All insulation layers 120 are made by integral pressing and stitching molding process. After molding, an anisotropic heat-conducting layer is formed, which not only retains the axial flexibility of the expansion joint to meet the axial and radial displacement compensation requirements under flue gas conditions, but also strengthens the radial sealing strength of the expansion joint. At the same time, the synergistic deformation characteristics of the fiber insulation material are utilized to avoid the insulation layer 120 generating reverse thrust when the expansion joint is thermally displaced, effectively offsetting stress concentration.

[0032] Each insulation layer 120 is a composite structure, including ceramic fiber cloth 121 and high-purity zirconium aluminum-containing cotton 122. The ceramic fiber cloth 121 completely covers the outside of the high-purity zirconium aluminum-containing cotton 122. The two are combined into a whole through a composite molding process, eliminating the method of filling cotton separately. The ceramic fiber cloth 121 provides structural protection for the insulation layer 120, preventing the high-purity zirconium aluminum-containing cotton 122 from loosening and falling off during thermal displacement. The high-purity zirconium aluminum-containing cotton 122 plays a role in high-temperature insulation, effectively blocking the heat transfer of high-temperature flue gas inside the expansion element 110 and reducing the risk of overheating of the external structure.

[0033] In addition, the connector 140 includes a second bolt 141 and a stud 142, which are differentiated and detachable designs to fix different structures respectively. The second bolt 141 is used to fix the end of the three-layer composite structure of the expansion element 110 itself, and to connect the inner liner 115 to the end of the expansion element 110. By locking the second bolt 141, it is ensured that the three-layer structure of the expansion element 110 does not separate under thermal cycling and media impact, and at the same time, the inner liner 115 is reliably fixed. The stud 142 is specifically used to connect and fix the insulation layer 120 to the expansion element 110. One end of the stud 142 is connected to the outer wall of the expansion element 110, and the other end penetrates the insulation layer 120 and locks it. The through locking of the stud 142 ensures that the insulation layer 120 and the expansion element 110 are tightly connected, and prevents the insulation layer 120 from radially slipping or bulging during thermal displacement.

[0034] The multi-layer sealing structure 130 covers the outside of the insulation layer 120 and is the outer sealing and protection structure of the expansion joint. It includes a polytetrafluoroethylene film 131 and a high-strength impregnated fiberglass cloth 132. The polytetrafluoroethylene film 131 is the middle core sealing layer, and the high-strength impregnated fiberglass cloth 132 layers are attached to both its inner and outer sides. The three are combined into a whole by hot pressing process to form an integrated composite sealing layer. The hot-pressing process ensures the bonding strength between the polytetrafluoroethylene film 131 and the high-strength impregnated fiberglass cloth 132 layer, eliminating the risk of interlayer loosening. The polytetrafluoroethylene film 131 gives the multi-layer sealing structure 130 excellent sealing wear resistance, high temperature resistance and media barrier properties, while the inner and outer high-strength impregnated fiberglass cloth 132 layers strengthen the overall structural strength and tensile strength of the composite sealing layer. This allows the multi-layer sealing structure 130 to adapt to the thermal displacement deformation of the expansion joint, maintaining stable dynamic sealing and pressure bearing capacity during the start-up and shutdown of the waste gas boiler and the hot and cold cycles of the expansion joint, thus avoiding loosening and edge curling failure of the sealing layer.

[0035] The metal frame 150 is located on the outside of the multi-layer sealing structure 130, providing external structural support for the entire expansion joint and ensuring its overall structural stability. Side pads 151 are fixed to the inner wall of the metal frame 150 by first bolts 152. The side pads 151 are arranged opposite to the outer side of the insulation layer 120, with all multiple insulation layers 120 located inside the side pads 151. The side pads 151 and the metal frame 150 are separate structures, uniformly fixed circumferentially by the first bolts 152. This ensures that the side pads 151 can move synchronously with the metal frame 150 during operation, adapting to the thermal displacement deformation of the expansion joint. Simultaneously, the side pads 151 effectively prevent high-temperature flue gas from directly impacting the metal frame 150, significantly reducing the risk and probability of overheating of the metal frame 150. Together with the insulation layer 120, they form a synergistic thermal insulation protection, improving the overall high-temperature resistance of the expansion joint.

[0036] The inner liner 115 is a direct protective component against flue gas scouring. One end of it is fixedly connected to the end of the expansion element 110 by a first bolt 152. This first bolt 152 simultaneously locks and fixes the ends of the three-layer structure of the expansion element 110: acid and alkali resistant glass fiber coated fluoropolymer cloth 111, high-temperature elastic alloy wire mesh 112, and high-temperature resistant corrosion-resistant non-metallic sealing material 113, achieving two goals at once. The other end of the inner liner 115 is suspended in the medium channel 114 without any fixed constraints. This allows the inner liner 115 to directly resist the scouring and corrosion of high-temperature flue gas, protecting the main structure of the expansion element 110 and reducing wear and thermal damage caused by direct scouring. It also allows the inner liner 115 to deform freely with the thermal displacement of the expansion joint, avoiding additional stress caused by deformation. At the same time, the suspended design does not obstruct the normal flow of flue gas in the medium channel 114, balancing protection and the deformation compensation capability of the expansion joint.

[0037] The implementation principle of the non-metallic expansion joint for a tube sheet type waste gas boiler in this application embodiment is as follows: it achieves a comprehensive effect of thermal displacement compensation, multiple insulation and dynamic sealing, which can effectively offset the thermal displacement stress and medium pressure fluctuation caused by high temperature flue gas, reduce the thermal stress and expansion difference between the tube sheet and the pipeline, and reduce the risk of weld cracking; at the same time, the detachable design of each structure and the coordinated arrangement of auxiliary protection structures further improve the structural stability, high temperature resistance and maintenance convenience of the expansion joint, and ensure the long-term stable operation of the waste gas boiler.

[0038] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A non-metallic expansion joint for a tube sheet type waste gas boiler, characterized in that: It includes a multi-layer composite expansion element (110), a thermal insulation layer (120), and a multi-layer sealing structure (130). The thermal insulation layer (120) wraps around the expansion element (110), and the multi-layer sealing structure (130) wraps around the thermal insulation layer (120). The expansion element (110), the thermal insulation layer (120), and the multi-layer sealing structure (130) are detachably connected to each other by connectors (140).

2. The non-metallic expansion joint for a tube sheet type waste gas boiler according to claim 1, characterized in that: The expansion element (110) includes acid and alkali resistant glass fiber coated with fluoropolymer cloth (111), high temperature elastic alloy wire mesh (112), and high temperature resistant corrosion-resistant non-metallic sealing material (113). The acid and alkali resistant glass fiber coated with fluoropolymer cloth (111), the high temperature elastic alloy wire mesh (112), and the high temperature resistant corrosion-resistant non-metallic sealing material (113) are arranged concentrically from the outside to the inside.

3. The non-metallic expansion joint for a tube sheet type waste gas boiler according to claim 2, characterized in that: The high-temperature elastic alloy wire mesh (112) is embedded in the matrix of the high-temperature corrosion resistant non-metallic sealing material (113) in a three-dimensional braided structure. The matrix of the high-temperature corrosion resistant non-metallic sealing material (113) forms a prestress compensation structure with the inner wall of the expansion element (110) through an epoxy resin impregnation process.

4. The non-metallic expansion joint for a tube sheet type waste gas boiler according to claim 1, characterized in that: The insulation layer (120) is provided with at least one layer, and multiple layers of the insulation layer (120) are arranged in concentric rings to wrap around the expansion element (110) and the multiple layers of the insulation layer (120) are pressed and sewn together to form an anisotropic heat-conducting layer.

5. A non-metallic expansion joint for a tube sheet type waste gas boiler according to claim 1, characterized in that: Each insulation layer (120) includes ceramic fiber cloth (121) and high-purity zirconium aluminum-containing cotton (122), wherein the ceramic fiber cloth (121) covers the high-purity zirconium aluminum-containing cotton (122), and the ceramic fiber cloth (121) and the high-purity zirconium aluminum-containing cotton (122) are composite molded.

6. A non-metallic expansion joint for a tube sheet type waste gas boiler according to claim 1, characterized in that: It also includes a metal frame (150) and a side pad (151), the metal frame (150) being disposed on the outside of the multi-layer sealing structure (130), the side pad (151) being fixed to the inner wall of the metal frame (150) by a first bolt (152), and the multi-layer insulation layer (120) being disposed on the inside of the side pad (151).

7. A non-metallic expansion joint for a tube sheet type waste gas boiler according to claim 1, characterized in that: The multilayer sealing structure (130) includes a polytetrafluoroethylene film (131) and a high-strength impregnated fiberglass cloth (132). The polytetrafluoroethylene film (131) is formed into a composite layer with the high-strength impregnated fiberglass cloth (132) layers on the inner and outer sides of the polytetrafluoroethylene film (131) by a hot pressing process.

8. A non-metallic expansion joint for a tube sheet type waste gas boiler according to claim 2, characterized in that: The connector (140) includes a second bolt (141) and a stud (142). The two ends of the acid and alkali resistant glass fiber coated with fluoropolymer cloth (111), the high temperature elastic alloy wire mesh (112) and the high temperature resistant corrosion-resistant non-metallic sealing material (113) are respectively fixed by the second bolt (141), and the multi-layer insulation layer (120) is fixed by the stud (142).

9. A non-metallic expansion joint for a tube sheet type waste gas boiler according to claim 8, characterized in that: The expansion element (110) has a medium channel (114) for medium flow on its inner side. The expansion element (110) is also provided with an inner liner (115). One end of the inner liner (115) is fixed to the expansion element (110) by the second bolt (141), and the other end of the inner liner (115) is suspended in the medium channel (114).

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