Multi-layer composite self-repairing heat tracing pipe

Abstract

The application discloses a kind of multilayer composite self-repairing heat tracing pipe, it is related to heat tracing pipe technical field, it can solve the problem of low heat transfer efficiency of traditional heat tracing pipe, also can solve the problem of heat transfer efficiency decline, electric leakage and scald personnel when heat tracing pipe appears breakage, including: inner tube, outer wall surface is provided with linear groove, outer surface is sprayed with coating;Transition adhesive layer, coating is in the coating outer surface of inner tube;Electric heating wire, by cold extrusion process is fixed in the linear groove of inner tube, and recess is filled with heat-conducting silicone grease;Insulating ceramic fiber layer;Heat insulation adhesive layer;Buffer layer;Self-repairing layer.Inner tube uses high-thermal-conductivity chrome zirconium copper material, cooperates zirconia-mullite composite ceramic coating, both guarantees insulating property, and also improves heat conduction efficiency;Self-repairing layer uses ternary ethylene-propylene rubber and hydrogenated nitrile rubber blend matrix, and adds modified nano montmorillonite, improves the strength and aging resistance of matrix.

Description

Technical Field

[0001] This invention belongs to the field of heat tracing pipe technology, specifically, it relates to a multi-layer composite self-healing heat tracing pipe. Background Technology

[0002] In recent years, the measurement of flue gas from pollution sources has shifted from the original constant potential electrolysis method to infrared and ultraviolet methods. When using infrared flue gas analyzers to test the content of sulfur dioxide, nitrogen oxides, carbon monoxide, and oxygen on-site, the flue gas treatment adopts full-process heating, condensing the gas in the pre-processor, and then entering the analyzer for data analysis.

[0003] However, traditional heat tracing pipes have low heat transfer efficiency and are prone to damage due to harsh working environments, leading to decreased heat transfer efficiency, leakage, and burns.

[0004] No effective solutions have yet been proposed to address the problems in the relevant technologies.

[0005] Therefore, in order to solve the above problems, the present invention provides a multi-layer composite self-healing heat tracing pipe. Summary of the Invention

[0006] In order to overcome the above-mentioned technical problems, the purpose of this invention is to provide a multi-layer composite self-healing heat tracing pipe.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A multi-layer composite self-healing heat tracing pipe, comprising:

[0009] The inner tube has linear grooves on its outer wall and a coating with a thickness of 50-80μm sprayed on its outer surface.

[0010] A transitional adhesive layer, coated on the outer surface of the inner tube's coating, with a thickness of 5-10 μm;

[0011] The heating wire is fixed in the linear groove of the inner tube by cold extrusion process, and the groove is filled with thermally conductive silicone grease.

[0012] An insulating ceramic fiber layer is wrapped around the transition adhesive layer and the heating wire.

[0013] A thermal insulation adhesive layer is coated on the outer surface of the insulating ceramic fiber layer, with a thickness of 1-2 mm.

[0014] A buffer layer is filled outside the thermal insulation adhesive layer, and short carbon fiber chopped strands are dispersed in the buffer layer;

[0015] A self-healing layer is wrapped around the buffer layer. The matrix of the self-healing layer is a blend of EPDM rubber and hydrogenated nitrile butadiene rubber. Nano-montmorillonite is dispersed in the blend. The self-healing layer contains double-walled microcapsules with a diameter of 50-100 μm. The inner wall of the microcapsule is polyurethane, the outer wall is polyurea, and the core is liquid silicone resin containing γ-aminopropyltriethoxysilane and hindered phenolic antioxidant 1010.

[0016] The wear-resistant layer is a surface-modified rubber that covers the outside of the self-healing layer;

[0017] The inner tube consists of at least three tubes, and the buffer layer between adjacent inner tubes is filled with aluminum silicate insulation strips.

[0018] As a preferred embodiment of the present invention, the inner tube is made of chromium zirconium copper and is roughened by sandblasting. The coating on the outer surface of the inner tube is a zirconium oxide-mullite composite ceramic coating, wherein the mass ratio of zirconium oxide to mullite is 6:4 and the porosity of the coating is ≤3%.

[0019] As a preferred embodiment of the present invention, the transition adhesive layer is made of alumina sol modified with γ-aminopropyltriethoxysilane, wherein the amount of γ-aminopropyltriethoxysilane modification in the transition adhesive layer is 2-3% of the mass of the alumina sol.

[0020] As a preferred embodiment of the present invention, the heating wire is woven from tin-plated copper wire, and the insulating ceramic fiber layer is woven from polycrystalline mullite fiber.

[0021] As a preferred embodiment of the present invention, the heat-insulating adhesive layer is made of aluminum silicate fiber and silicone adhesive, the thermal conductivity of the heat-insulating adhesive layer is ≤0.05W / (m·K), and the bonding strength at room temperature is ≥1.2MPa.

[0022] In a preferred embodiment of the present invention, the buffer layer contains boron nitride at a mass ratio of 15-25%, and carbon fiber stubs at a length of 0.5-1 mm at a mass ratio of 3-5%.

[0023] As a preferred embodiment of the present invention, in the self-healing layer, the blending mass ratio of EPDM rubber and hydrogenated nitrile rubber is 7:3-6:4, the mass percentage of nano-montmorillonite in the self-healing layer is 2-4%, and the nano-montmorillonite is modified with silane coupling agent KH560. In the core of the microcapsule, the mass percentage of γ-aminopropyltriethoxysilane is 1-3%, and the mass percentage of hindered phenolic antioxidant 1010 is 0.5-1%.

[0024] As a preferred embodiment of the present invention, the surface-modified rubber of the wear-resistant layer is nitrile rubber grafted with γ-aminopropyltriethoxysilane.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. In this invention, the inner tube is made of high thermal conductivity chromium zirconium copper material and is roughened by sandblasting. Combined with a zirconium oxide-mullite composite ceramic coating, it not only ensures insulation but also improves heat conduction efficiency. The heating wire is fixed in the groove through a cold extrusion process, and the groove is filled with thermally conductive silicone grease, which greatly increases the contact area between the heating wire and the inner tube and the heat conduction efficiency. The double heat insulation structure of the insulating ceramic fiber layer and the heat insulation adhesive layer effectively reduces heat loss and ensures stable heat tracing of flue gas throughout the pipe, solving the problems of low heat transfer efficiency and large temperature fluctuations in traditional heat tracing pipes.

[0027] 2. In this invention, the transition adhesive layer and the thermal insulation adhesive layer enhance the bonding force between the inner tube coating and the insulation layer, and between the insulation layer and the buffer layer, respectively, thus avoiding delamination during long-term use. The short-cut carbon fibers added to the buffer layer improve the structural strength of the layer while also providing flexibility, effectively absorbing the thermal expansion and contraction stress of the pipeline and preventing the heating wire from breaking. The aluminum silicate thermal insulation strips between adjacent inner tubes achieve thermal insulation and isolation between multiple tubes, avoiding mutual temperature interference and further improving the stability of the overall structure.

[0028] 3. In this invention, the self-healing layer uses a blend of EPDM rubber and hydrogenated nitrile rubber as the matrix, and adds modified nano-montmorillonite to improve the strength, aging resistance, and media resistance of the matrix; it uses double-walled microcapsules, which have stronger impact resistance than traditional single-walled microcapsules and can avoid accidental rupture under non-damaged conditions; the γ-aminopropyltriethoxysilane added to the core enhances the bonding force between the repaired silicone resin and the matrix, and the hindered phenolic antioxidant 1010 slows down the aging rate of the repair layer, ensuring a long-lasting repair effect and significantly extending the service life of the heat tracing pipe, solving the problems of traditional heat tracing pipes being easily damaged and unable to be repaired after damage. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is an overall cross-sectional view of the present invention;

[0031] Figure 2 This is a cross-sectional view of the inner tube of the present invention.

[0032] Figure label:

[0033] 1. Inner tube; 2. Heating wire; 3. Insulating ceramic fiber layer; 4. Buffer layer; 5. Self-healing layer; 6. Wear-resistant layer; 7. Transition adhesive layer; 8. Thermal insulation adhesive layer. Detailed Implementation

[0034] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention:

[0035] Example: Please refer to Figure 1-2 According to an embodiment of the present invention, a multilayer composite self-healing heat tracing pipe includes the following parts:

[0036] Inner tube 1: A chromium-zirconium copper tube with a diameter of 10mm and a wall thickness of 1.5mm is selected. The outer wall of the tube is roughened by sandblasting to improve the adhesion of subsequent coatings. A linear groove with a width of 2mm and a depth of 1mm is made along the roughened outer wall of the inner tube, extending parallel to the axis of the inner tube. A zirconia-mullite composite ceramic coating is prepared on the outer surface of the inner tube using atmospheric plasma spraying, with a zirconia to mullite mass ratio of 6:4. The coating thickness is controlled at 65μm, and the porosity of the coating is tested to be 2.2%, meeting the requirements for insulation and thermal conductivity.

[0037] Transitional adhesive layer 7: Alumina sol modified with γ-aminopropyltriethoxysilane is used as the transitional adhesive layer material, wherein the modification amount of γ-aminopropyltriethoxysilane is 2.5% of the mass of the alumina sol. The modified alumina sol is coated onto the outer surface of the composite ceramic coating of the inner tube by dip coating process, and then cured by baking at 120℃ for 30 minutes after drying at room temperature, finally forming a transitional adhesive layer with a thickness of 8μm, which is used to enhance the bonding stability between the inner tube coating and the subsequent insulation layer.

[0038] Heating wire 2: A flexible metal braided heating wire made of tin-plated copper wire, with a wire diameter of 0.5mm and a rated power of 20W / m. A layer of thermally conductive silicone grease is evenly applied into the linear groove of the inner tube. After the heating wire is embedded into the groove, a cold extrusion process is used to fix the heating wire in the groove, ensuring that the heating wire is in close contact with the inner wall of the groove. The thermally conductive silicone grease fills all gaps in the groove, improving heat conduction efficiency.

[0039] Insulating ceramic fiber layer 3: The fiber cloth is made of polycrystalline mullite fiber and is tightly wrapped around the transition adhesive layer 7 and the heating wire 2. There are 2 wrapping layers and the wrapping density is 1.2g / cm³, forming an insulating ceramic fiber layer, which plays a role in insulation and preliminary heat preservation.

[0040] Thermal insulation adhesive layer 8: Aluminum silicate fiber and silicone adhesive are mixed evenly at a mass ratio of 3:7 to form a thermal insulation adhesive material. This material is coated onto the outer surface of the insulating ceramic fiber layer by a spraying process. After curing at 150℃ for 60 minutes, a thermal insulation adhesive layer with a thickness of 1.5 mm is formed. Its thermal conductivity is tested to be 0.04 W / (m·K), and its room temperature bonding strength is 1.4 MPa, which has both thermal insulation and bonding functions.

[0041] Buffer layer 4: A buffer layer material is formed by mixing 20% ​​boron nitride and 4% chopped carbon fiber with silicone rubber as the matrix. This material is then filled into the outer layer of the thermal insulation adhesive layer 8. Simultaneously, six prepared inner tubes are selected as a group, and aluminum silicate thermal insulation strips are filled in the buffer layer area between adjacent inner tubes to ensure thermal insulation between adjacent inner tubes and prevent temperature interference.

[0042] Self-healing layer 5: A matrix is ​​made of a blend of EPDM rubber and hydrogenated nitrile butadiene rubber at a mass ratio of 6.5:3.5. 3% by mass of nano-montmorillonite modified with silane coupling agent KH560 is added to the matrix. After thorough mixing, double-walled microcapsules with a diameter of 50-100 μm (microcapsule addition amount is 15% of the matrix mass) are added. The inner wall of the double-walled microcapsules is polyurethane, the outer wall is polyurea, and the core is liquid silicone resin containing γ-aminopropyltriethoxysilane (2% by mass) and hindered phenolic antioxidant 1010 (0.8% by mass). The above mixture is then extruded onto the outside of buffer layer 4 to form a self-healing layer with a thickness of 2 mm.

[0043] Wear-resistant layer 6: Nitrile rubber grafted with γ-aminopropyltriethoxysilane is selected as the wear-resistant layer material. It is coated on the outside of the self-healing layer 5 through a vulcanization coating process, with a coating thickness of 1.5mm, to form the final multi-layer composite self-healing heat tracing pipe.

[0044] The working principle of a multi-layer composite self-healing heat tracing pipe is as follows: After the heat tracing pipe is assembled, it is fixed to the outside of the flue gas sampling pipeline of the pollution source by pipe clamps, ensuring that the heat tracing pipe and the sampling pipeline are parallel and in close contact. The end of the heating wire 2 is electrically connected to an external power source through a sealed terminal block. The connection point is sealed with high-temperature resistant insulating sealant to prevent short circuits or leakage faults caused by the intrusion of flue gas and water vapor. Temperature setting and control are achieved through a matching temperature control system. This temperature control system adopts closed-loop feedback control logic. The actual working temperature of the heat tracing pipe is collected in real time by a temperature sensor embedded in the insulating ceramic fiber layer 3 of the heat tracing pipe, and the temperature signal is transmitted to the temperature control host. The temperature control host presets a target temperature range according to the core requirements of flue gas sampling (such as avoiding flue gas condensation and ensuring the stability of sampled components). By comparing the deviation between the actual collected temperature and the preset target temperature, the host automatically adjusts the current or voltage output to the heating wire 2, thereby achieving precise control of the heating power of the heating wire 2 and ensuring that the heat tracing pipe is always maintained within the temperature range that meets the sampling requirements. After the pollutant flue gas flows into the inner pipe 1, the heating wire 2 is energized and heats up. The heat is quickly conducted to the flue gas inside the pipe through the inner pipe 1, achieving full-process heat tracing. The insulating ceramic fiber layer 3 and the heat-insulating adhesive layer 8 work together to reduce heat loss and ensure heat tracing efficiency. The buffer layer 4 absorbs the stress generated by the thermal expansion and contraction of the pipeline, preventing the heating wire 2 from breaking. In complex field environments, if the wear-resistant layer 6 is damaged by external force, the double-layer capsule wall microcapsules in the self-repairing layer 5 rupture. The liquid silicone resin in the capsule core quickly penetrates to the damaged area under the action of γ-aminopropyltriethoxysilane, reacts with air moisture, cross-links and solidifies, and at the same time, the hindered phenolic antioxidant delays the aging of the repair layer, achieving self-repair of the damage. The aluminum silicate insulation cotton strips between adjacent inner pipes 1 effectively avoid temperature interference between multiple pipes and ensure uniform heating temperature of the flue gas in each pipe.

[0045] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0046] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-layer composite self-healing heat tracing pipe, characterized in that: include: The inner tube (1) has a linear groove on its outer wall and a coating with a thickness of 50-80μm. The outer wall of the inner tube (1) is made of chromium zirconium copper and is roughened by sandblasting. The coating on the outer surface of the inner tube (1) is a zirconium oxide-mullite composite ceramic coating, wherein the mass ratio of zirconium oxide to mullite is 6:4 and the porosity of the coating is ≤3%. A transition adhesive layer (7) is applied to the outer surface of the coating of the inner tube (1) with a thickness of 5-10 μm; The heating wire (2) is fixed in the linear groove of the inner tube (1) by cold extrusion process, and the groove is filled with thermally conductive silicone grease. An insulating ceramic fiber layer (3) is wrapped around the transition adhesive layer (7) and the heating wire (2); A thermal insulation adhesive layer (8) is coated on the outer surface of the insulating ceramic fiber layer (3) with a thickness of 1-2 mm. The thermal insulation adhesive layer (8) is made of aluminum silicate fiber and organosilicon adhesive. The thermal conductivity of the thermal insulation adhesive layer (8) is ≤0.05W / (m・K) and the bonding strength at room temperature is ≥1.2MPa. A buffer layer (4) is filled on the outer layer of the thermal insulation adhesive layer (8), wherein short carbon fiber stubs are dispersed in the buffer layer (4); The self-healing layer (5) is wrapped around the buffer layer (4). The matrix of the self-healing layer (5) is a blend of EPDM rubber and hydrogenated nitrile butadiene rubber. Nano-montmorillonite is dispersed in the blend. The self-healing layer (5) contains double-walled microcapsules with a diameter of 50-100 μm. The inner wall of the microcapsule is polyurethane, the outer wall is polyurea, and the core is liquid silicone resin containing γ-aminopropyltriethoxysilane and hindered phenolic antioxidant 1010. The blending mass ratio of EPDM rubber and hydrogenated nitrile butadiene rubber is 7:3-6:

4. The mass percentage of nano-montmorillonite is 2-4%, and the nano-montmorillonite is modified with silane coupling agent KH560. In the core of the microcapsule, the mass percentage of γ-aminopropyltriethoxysilane is 1-3%, and the mass percentage of hindered phenolic antioxidant 1010 is 0.5-1%. The wear-resistant layer (6) is a surface-modified rubber that covers the outside of the self-healing layer (5); The inner tube (1) consists of at least 3 tubes, and the buffer layer (4) between adjacent inner tubes (1) is filled with aluminum silicate heat insulation strips.

2. The multi-layer composite self-healing heat tracing pipe according to claim 1, characterized in that: The transition adhesive layer (7) is made of alumina sol modified with γ-aminopropyltriethoxysilane, wherein the amount of γ-aminopropyltriethoxysilane in the transition adhesive layer (7) is 2-3% of the mass of the alumina sol.

3. The multi-layer composite self-healing heat tracing pipe according to claim 1, characterized in that: The heating wire (2) is woven from tin-plated copper wire, and the insulating ceramic fiber layer (3) is woven from polycrystalline mullite fiber.

4. The multi-layer composite self-healing heat tracing pipe according to claim 1, characterized in that: The buffer layer (4) contains boron nitride at a mass ratio of 15-25%, and carbon fiber stubs at a length of 0.5-1 mm, with a mass ratio of 3-5%.

5. The multi-layer composite self-healing heat tracing pipe according to claim 1, characterized in that: The surface-modified rubber of the wear-resistant layer (6) is nitrile rubber grafted with γ-aminopropyltriethoxysilane.

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