Multilayer composite noise reduction material used in transformer equipment insulating oil, application and electric reactor

Abstract

The invention discloses a multi-layer composite noise reduction material used in transformer equipment insulating oil, application and an electric reactor, and belongs to the technical field of composite acoustic materials. The cork rubber insulation board is composed of cork rubber and insulation paper boards arranged at the two ends of the cork rubber. One insulating paper board is arranged on the inner wall of an oil tank of the power transformation equipment, the other insulating paper board is provided with a through hole, and a cavity connected with the through hole is arranged in the cork rubber. The structure of the perforated plate and the cavity is easy to form a Helmholtz resonance sound absorption structure, and the structure has a remarkable absorption effect on long-wavelength low-frequency noise. Therefore, the composite material can still achieve the excellent performance that the 100 Hz sound absorption coefficient is larger than 0.3 and the noise reduction coefficient is not smaller than 0.75 in the severe acoustic environment with high sound velocity and long wavelength in oil, and the bottlenecks that a conventional porous material is poor in sound absorption effect in oil and the design of a resonant cavity is harsh are effectively overcome.

Description

Technical Field

[0001] This invention belongs to the field of composite acoustic materials technology, specifically relating to a multi-layer composite noise reduction material for use in insulating oil of power equipment and its application in reactors. Background Technology

[0002] With the rapid advancement of ultra-high voltage (UHV) power transmission projects, noise pollution from UHV reactors and other transformer equipment during operation has become increasingly prominent. Studies show that the noise from UHV reactors primarily originates from the electromagnetic force in the air gap of the core, with noise levels significantly higher than transformers of the same voltage level. Near-field sound pressure levels can reach 74.0-76.1 dB(A), and the noise energy is concentrated in the low-frequency band, including the 100 Hz fundamental frequency and its harmonics. This type of low-frequency noise has long wavelengths, slow attenuation, and strong penetrating power, easily leading to noise exceeding standards at the substation boundary (especially when the nighttime limit is 50 dB(A) for Class 2 acoustic environment functional zones), impacting the surrounding acoustic environment quality and ecologically sensitive areas. Although the industry has attempted to use technologies such as sound barriers and sound enclosures for noise control, these methods have significant limitations: sound barriers are only effective in the sound shadow zone, and excessively high barriers pose risks to wind and earthquake resistance; sound enclosures may affect equipment heat dissipation and maintenance convenience, and their noise reduction performance also faces bottlenecks.

[0003] In terms of noise reduction technology for the equipment itself, current measures still face multiple challenges. The magnetostriction optimization of silicon steel sheets has reached its technological limit, leaving limited room for further noise reduction. Damping materials applied to insulating oil, such as nitrile rubber or cork rubber, often have damping peaks that are difficult to match the 50-70℃ operating temperature range of transformer oil, resulting in unsatisfactory vibration reduction effects. Furthermore, the sound velocity inside oil is much higher than in air (approximately 1300-1400 m / s), making the wavelength of 100 Hz noise reach 13-14 meters, rendering conventional porous sound-absorbing materials ineffective. While resonant sound-absorbing structures are a potential solution, they require addressing multiple challenges simultaneously, including frequency matching, oil resistance, and spatial size limitations (to avoid insufficient insulation distance). Therefore, developing a composite noise reduction material that can adapt to the oil environment, possesses both wide-band sound absorption and high-efficiency damping characteristics, and meets the requirements of miniaturization and lightweighting has become a key technical problem urgently needing breakthroughs in the field of noise control for ultra-high voltage substation equipment. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a multi-layer composite noise reduction material for use in the insulating oil of power equipment, and its application in reactors. The multi-layer composite noise reduction material for use in the insulating oil of power equipment provided by the present invention has a sound absorption coefficient >0.3 at 100 Hz and a noise reduction coefficient not less than 0.75, thus fulfilling the objectives of low-frequency high efficiency and wide-bandwidth effectiveness. Its overall thickness is 80 mm, and its surface density is <36 kg / m³. 2Its acoustic performance can achieve a sound insulation of >45 dB, which meets the requirements of high-efficiency sound insulation under the premise of small thickness and light weight.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a multi-layer composite noise reduction material for use in insulating oil of power equipment, comprising cork rubber and insulating paperboard disposed at both ends of the cork rubber. An insulating cardboard is laid on the inner wall of the transformer equipment tank, and another insulating cardboard has perforations. The cork rubber has a cavity connected to the perforations.

[0006] In some embodiments of the present invention, the insulating paperboard includes any one of hot-dip galvanized carbon steel plate, stainless steel plate, basalt fiber felt, glass wool fiber felt, constraint damping sound insulation board, and cellulose insulating paper.

[0007] In some embodiments of the present invention, the cork rubber is nitrile-based cork rubber, which has the highest damping peak at 50~70°C.

[0008] In some embodiments of the present invention, the insulating paperboard has the same shape as the cork rubber end face, a thickness of 4-6 mm, and a cork rubber height of 10-13 cm. The cavity is a cylindrical cavity with the same height as the cork rubber. The perforation is located at the center of the insulating cardboard. The diameter of the perforation is 0.8-1.1 mm.

[0009] In some embodiments of the present invention, the thickness of the insulating paperboard is 4-6 mm; the length and width of the cork rubber are equal, with a length of 38-42 cm and a height of 10-13 cm; and the diameter of the cavity is 30-34 cm.

[0010] In some embodiments of the present invention, the insulating paperboard has a thickness of 5 mm, the cork rubber has equal length and width of 40 cm and a height of 12 cm, the cavity has a diameter of 34 cm and a height of 12 cm, and the perforation has a diameter of 1 mm.

[0011] In some embodiments of the present invention, the insulating paperboard has a thickness of 5 mm, the cork rubber has equal length and width of 40 cm and a height of 13 cm, the cavity has a diameter of 30 cm and a height of 13 cm, and the perforation has a diameter of 0.9 mm.

[0012] In some embodiments of the present invention, the insulating paperboard has a thickness of 5 mm, the cork rubber has equal length and width of 40 cm and a height of 10 cm, the cavity has a diameter of 29 cm and a height of 10 cm, and the perforation has a diameter of 0.8 mm.

[0013] In some embodiments of the present invention, the method for preparing the cork rubber is as follows: The cork rubber comprises, by weight, 60-70 parts of nitrile rubber, 30-40 parts of cork particles, 0.8-1.2 parts of silane coupling agent, 4-7 parts of activator, 5-10 parts of plasticizer, 2 parts of vulcanizing agent, 25-40 parts of reinforcing agent, and 0.5-1.5 parts of accelerator. After degreasing, cork particles are mixed with a silane coupling agent to obtain modified cork particles; Nitrile rubber is plasticized and compounded to obtain a premixed rubber; Modified cork particles were added to the premixed adhesive and then mixed to obtain a composite adhesive. The composite rubber compound is molded, vulcanized, and left to stand to obtain cork rubber.

[0014] In a second aspect, the present invention provides the application of the multilayer composite noise reduction material for use in the insulating oil of power equipment as described in the first aspect in noise reduction of power equipment.

[0015] A third aspect of the present invention provides a reactor in which the inner wall of the reactor's oil tank is provided with the multi-layer composite noise reduction material for use in the insulating oil of power equipment as described in the first aspect.

[0016] In some embodiments of the present invention, the multi-layer composite noise reduction material used in the insulating oil of the power equipment covers an area of ​​not less than 50% on the inner wall of each side of the oil tank.

[0017] The beneficial effects of this invention are as follows: This invention provides a multi-layer composite noise reduction material for use in the insulating oil of power equipment. Through a multi-layer composite structure design using specific materials, it specifically addresses the challenge of low-frequency noise control in the insulating oil of power equipment such as ultra-high voltage reactors. Specifically, the core of this structure lies in the combined effect of a cork rubber layer, perforated insulating paperboard, and the cavity connecting them. On one hand, cork rubber itself has excellent damping and vibration reduction characteristics, helping to dissipate vibration energy. On the other hand, the structure of the perforated plate and the cavity easily forms a Helmholtz resonance sound-absorbing structure. This structure has a significant absorption effect on long-wavelength low-frequency noise (such as the prominent 100 Hz fundamental frequency and its harmonics noise of ultra-high voltage reactors). This allows the composite material to achieve excellent performance in the harsh acoustic environment of high sound velocity and long wavelength within oil, with a sound absorption coefficient greater than 0.3 at 100 Hz and a noise reduction coefficient of not less than 0.75, effectively overcoming the bottlenecks of poor sound absorption in oil by conventional porous materials and the demanding design requirements of the resonance cavity. Furthermore, this invention optimizes the vibration transmission path and improves structural stability. By arranging one layer of insulating paperboard on the inner wall of the transformer tank, and connecting another layer of perforated insulating paperboard to the cavity of the cork rubber layer, this structure establishes an effective damping and vibration isolation layer inside the equipment. The cork rubber layer can effectively suppress and dissipate the vibration energy transmitted from the core vibration to the tank wall through the insulating oil, reducing the radiation efficiency of the tank wall as a "secondary sound source." This design improves upon the previous problem of unsatisfactory vibration reduction effects of oil-immersed damping materials (such as nitrile rubber or cork rubber) due to poor damping peak temperature range matching or bearing pressure. Simultaneously, the insulating paperboard ensures the compatibility of the material with the internal insulation environment of the oil-immersed transformer.

[0018] The multi-layer composite noise reduction material for use inside the insulating oil of power equipment provided by this invention meets the engineering requirements of equipment miniaturization, lightweighting, and high safety. The overall thickness of this composite material is less than 15 cm, but its sound absorption coefficient for 100 Hz vibration waves reaches a considerable level of over 0.3. This achieves highly efficient noise reduction within the limited internal space of the transformer, avoiding the problems of external measures such as soundproof enclosures occupying large amounts of space and affecting operation and maintenance. Furthermore, the specification mentions that all materials used (such as cork rubber and insulating cardboard) are non-combustible, with a flammability rating of Class A. This significantly improves the safety and reliability of power equipment operation and avoids fire hazards introduced by the noise reduction material. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1This is a structural diagram of the multilayer composite noise reduction material used in the insulating oil of power equipment in an embodiment of the present invention, wherein a is the main view, b is the left view, and c is a cross-sectional view at position AA in the main view.

[0021] Figure 2 This is a structural diagram of the multi-layer composite noise reduction material for vibration isolation oil in an embodiment of the present invention, wherein a is the front view, b is the left view, and c is a cross-sectional view at position AA in the front view.

[0022] Figure 3 This refers to the damping coefficient of the cork rubber in this embodiment of the invention.

[0023] Among them, 1. Insulating cardboard, 2. Cork rubber. Detailed Implementation

[0024] In view of the problem that noise is difficult to control in existing ultra-high voltage reactors, this invention proposes a multi-layer composite noise reduction material for use in the insulating oil of power equipment and its application in reactors.

[0025] A typical embodiment of the present invention provides a multi-layer composite noise reduction material for use in insulating oil of power equipment, which is composed of cork rubber and insulating paperboard arranged at both ends of the cork rubber. An insulating cardboard is laid on the inner wall of the transformer equipment tank, and another insulating cardboard has a perforation in the center, with a cavity in the cork rubber connected to the perforation.

[0026] Currently, key technologies for noise reduction materials used in reactors, such as low-frequency noise reduction and wide-temperature-range operation, have not yet been mastered. Furthermore, acoustic materials used in large oil-filled equipment must meet the following requirements.

[0027] First, ensure that the oil has sufficiently good low-frequency acoustic performance, such as a low-frequency sound absorption coefficient of greater than 0.3 at 100 Hz.

[0028] Secondly, as a material system installed inside the fuel tank, it should ensure good oil resistance, and secondly, ensure that its damping peak is optimal at the service temperature of 50-70℃.

[0029] Third, the application of damping materials should be well matched with 100 Hz noise, applied pressure and shape factor (i.e. the ratio of the area of ​​the bearing surface to the area of ​​the non-bearing surface).

[0030] The multi-layer composite noise reduction material for use in insulating oil of power equipment provided by this invention cleverly solves the problem of low-frequency noise control in the insulating oil of ultra-high voltage power equipment through innovative material combination and structural design. It achieves multiple beneficial effects such as efficient sound absorption and vibration isolation, lightweight and compact design, and high safety and reliability, providing an effective solution for noise reduction of the equipment body.

[0031] I. Solving the problem of low-frequency sound absorption: The acoustic material involved in this invention adopts a Helmholtz resonant cavity structure to form standardized units, thus solving the problem of poor low-frequency sound absorption performance. As shown in Examples 1-5, the overall thickness is less than 15 cm, but the sound absorption coefficient of 100 Hz vibration wave reaches a considerable level of over 0.3.

[0032] Second, the oil resistance issue has been resolved: the entire material system contains only cork rubber and insulating paperboard. Insulating paperboard is a commonly used insulating material in transformers and reactors, and it does not have a problem with poor oil resistance. Furthermore, the cork rubber material uses nitrile-based cork rubber, which has excellent oil resistance.

[0033] Third, it solves the problem of thin and light materials: It adopts a Helmholtz resonant cavity design, targeting a frequency of 100Hz, thus controlling its maximum thickness to within 15 cm, without needing to meet the requirements of resistive sound-absorbing materials that absorb one-quarter of the sound wavelength. If resistive sound-absorbing materials were used, the thickness would need to reach over 2 meters.

[0034] Fourth, it solves the problem of using a single material for both sound absorption and vibration isolation: The modular structure allows it to be applied to both low-frequency sound absorption and vibration isolation of the transformer body. According to the test methods of DL / T 2085-2020 Technical Requirements for Noise Reduction Materials and Devices in Substations, the 100 Hz sound absorption coefficient of this invention reaches over 0.3, while the vibration isolation rate also reaches over 80%.

[0035] V. Solving the problem of parameter mismatch: The materials used in this invention are specially controlled and optimized for the service temperature threshold of 50-70℃. The nitrile rubber has the best damping peak at this temperature, and the nitrile-based cork rubber prepared based on this perfectly maintains the service temperature threshold, so that the material matches the temperature. In addition, through large-scale vibration isolation tests, the optimal bearing pressure and shape factor were obtained, ensuring that the vibration isolation rate of the material is >80% at 50-70℃.

[0036] In some embodiments of the present invention, the cork rubber is nitrile-based cork rubber, which has the highest damping peak at 50-70°C. The nitrile-based cork rubber used in this invention can precisely match the actual operating temperature environment of the insulating oil in transformer equipment, thereby achieving efficient vibration energy dissipation in the critical temperature range of the noise source. This characteristic directly addresses and solves the bottleneck problem of traditional nitrile rubber or cork rubber materials having difficulty matching the damping peak at the service temperature of transformer oil (50-70°C), resulting in poor vibration reduction effect. By enabling the material to exhibit optimal damping performance in this specific temperature range, the process of core vibration being transmitted to the tank wall through the insulating oil can be most effectively suppressed, weakening the generation and propagation of noise from the sound source, and significantly improving the noise reduction effect and reliability of the equipment under real operating conditions.

[0037] Furthermore, this nitrile-based cork rubber can also be used as a vibration isolation material, such as a vibration isolation material for reactor bodies, achieving a vibration isolation rate of over 80%. For example, the vibration isolation material has a sandwich structure, with insulating paperboard on both sides of the nitrile-based cork rubber. The difference from the multi-layer composite noise reduction material used in the insulating oil of power equipment is that it adopts a solid structure, with neither layer of insulating paperboard perforated.

[0038] In some embodiments of the present invention, the method for preparing the cork rubber is as follows: The cork rubber comprises, by weight, 60-70 parts of nitrile rubber, 30-40 parts of cork particles, 0.8-1.2 parts of silane coupling agent, 4-7 parts of activator, 5-10 parts of plasticizer, 2 parts of vulcanizing agent, 25-40 parts of reinforcing agent, and 0.5-1.5 parts of accelerator. After degreasing, cork particles are mixed with a silane coupling agent to obtain modified cork particles; Nitrile rubber is plasticized and compounded to obtain a premixed rubber; Modified cork particles were added to the premixed adhesive and then mixed to obtain a composite adhesive. The composite rubber compound is molded, vulcanized, and left to stand to obtain cork rubber.

[0039] The silane coupling agent is selected from any one or more of γ-aminopropyltriethoxysilane (Si-69) or bis-[γ-(triethoxysilyl)propyl]tetrasulfide (KH-550); the activator is selected from any one or more of zinc oxide (ZnO) and stearic acid (SA); the plasticizer is selected from any one or more of dioctyl phthalate (DOP) and dioctyl sebacate (DOS); the vulcanizing agent is sulfur; the reinforcing agent is selected from any one or more of carbon black N550, carbon black N660, and carbon black N330; and the accelerator is selected from any one or more of dithiodibenzothiazole (DM), tetramethylthiuram disulfide (TMTD), and N-cyclohexyl-2-benzothiazole sulfenamide (CZ).

[0040] In some embodiments of the present invention, during the preparation of the cork rubber, the degreasing treatment temperature of the cork particles is 75-85°C, the mixing temperature of the premixed rubber and the modified cork rubber is 110-120°C, the vulcanization temperature is 160-170°C, and the vulcanization pressure is 15-20 MPa.

[0041] In some embodiments of the present invention, the method for preparing the cork rubber includes the following steps: Step 1: Cork Particle Pretreatment Degreasing treatment: Place the cork particles in an ethanol solution with a concentration of 90-98% and reflux them at 75-85℃ for 4-6 hours; after treatment, dry them at 100-110℃ and a vacuum degree below -0.095 MPa for 2-4 hours to reduce the moisture content to below 5%.

[0042] Activation modification: Place the dried cork particles in a high-speed mixer, heat to 75-85℃, add silane coupling agent, and stir at 800-1200 r / min for 15-25 minutes to obtain modified cork particles.

[0043] Step 2: Plasticizing and Premixing of Rubber Matrix Plasticizing: Nitrile rubber is plasticized on a two-roll mill at a roller temperature of 50-60℃ until the Mooney viscosity (ML(1+4)100℃) drops to 40-50, thus obtaining plasticized rubber.

[0044] Premixing: Activator, plasticizer, and reinforcing agent are added sequentially to the plasticized rubber and mixed. The reinforcing agent (carbon black) is added in 3 batches, with an interval of 2-3 minutes between each addition, to obtain the premixed rubber.

[0045] Step 3: Compounding of rubber compounds The premixed rubber was transferred to an internal mixer, and the modified cork particles obtained in step 1 were added at 110-120℃ and 40-60 r / min. The mixture was then mixed for 8-12 minutes. Subsequently, the rubber compound was discharged to a two-roll mill, cooled to below 100℃, and vulcanizing agent and accelerator were added. After being mixed evenly, the compound was sheeted and cooled to obtain the composite rubber compound.

[0046] Step 4: Compression molding and vulcanization Compression molding: Place the cooled composite material into the mold, set the pressure to 15-20 MPa, the temperature to 140-150℃, and pre-compress for 5-8 minutes; Vulcanization: Keep the pressure constant and raise the temperature to 160-170℃. The vulcanization time is 15-20 minutes (adjust according to the product thickness, extend the time by 1 minute for every 1 mm increase in thickness).

[0047] Step 5: Post-processing Post-processing: After vulcanization, the product is taken out and cooled. It is then cooled for 24 hours in an environment of 25±2℃ and 50-60% relative humidity. After that, the edges are trimmed. The trimmed product is placed in a constant temperature and humidity chamber and aged at 70℃ for 72 hours to eliminate internal stress, thus obtaining cork rubber.

[0048] The cork rubber provided by this invention has good oil resistance and a damping coefficient that is at its maximum at 50-70℃, meeting the requirements for acoustic materials used in large oil-filled equipment.

[0049] In some embodiments of the present invention, the insulating paperboard includes any one of hot-dip galvanized carbon steel plate, stainless steel plate, basalt fiber felt, glass wool fiber felt, constrained damping sound insulation board, and cellulose insulating paper. All materials are non-combustible, with a combustion performance rating of A. Glass wool with poor melting point or fire resistance can be protected with basalt fiber felt to prevent melting or pulverization. Through flexible material configuration, the entire noise reduction structure can precisely adapt to the complex and harsh working environment inside transformer oil, achieving an optimal balance of sound absorption, sound insulation, damping, and weather resistance while ensuring insulation safety.

[0050] In some embodiments of the present invention, the insulating paperboard has the same shape as the cork rubber end face, and the thickness is 4-6 mm, specifically 4 mm, 5 mm, 6 mm, etc., and the height of the cork rubber is 10-13 cm, specifically 10 cm, 11 cm, 12 cm, 13 cm, etc. The cavity is a cylindrical cavity with the same height as the cork rubber. The perforation is located at the center of the insulating paperboard; The diameter of the perforation is 0.8-1.1 mm, specifically 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, etc.

[0051] This invention utilizes precisely designed dimensional parameters (insulating paperboard thickness, cork rubber height, cavity shape, and perforation diameter) to precisely tune the "perforated plate-cavity" structure into a highly efficient Helmholtz resonant sound absorber, ensuring its resonant frequency accurately matches the prominent 100 Hz fundamental frequency noise of ultra-high voltage reactors. The 4-6 mm thickness of the insulating paperboard guarantees the rigidity of the perforated plate, while the 10-13 cm height of the cork rubber (i.e., cavity height) and the 0.8-1.1 mm diameter of the tiny perforations synergistically determine the resonant frequency. This allows it to strongly absorb low-frequency sound waves with extremely long wavelengths even in environments with extremely high sound speeds within oil, converting sound energy into heat energy, thereby achieving highly efficient low-frequency noise reduction at its source.

[0052] In some embodiments of the present invention, the thickness of the insulating paperboard is 4-6 mm; the length and width of the cork rubber are equal, with a length of 38-42 cm and a height of 10-13 cm; and the diameter of the cavity is 30-34 cm.

[0053] In some embodiments of the present invention, the thickness of the insulating paperboard is 5 mm, the length and width of the cork rubber are equal, the length is 40 cm and the height is 12 cm; the diameter of the cavity is 34 cm and the height is 12 cm; and the diameter of the perforation is 1 mm.

[0054] In some embodiments of the present invention, the insulating paperboard has a thickness of 5 mm, the cork rubber has equal length and width of 40 cm and a height of 13 cm, the cavity has a diameter of 30 cm and a height of 13 cm, and the perforation has a diameter of 0.9 mm.

[0055] In some embodiments of the present invention, the insulating paperboard has a thickness of 5 mm, the cork rubber has equal length and width of 40 cm and a height of 10 cm, the cavity has a diameter of 29 cm and a height of 10 cm, and the perforation has a diameter of 0.8 mm.

[0056] A second typical embodiment of the present invention provides the application of multilayer composite noise reduction material for use in the insulating oil of power equipment in noise reduction of power equipment.

[0057] A third typical embodiment of the present invention provides a reactor, wherein the inner wall of the reactor's oil tank is provided with the aforementioned multi-layer composite noise reduction material for use in the insulating oil of power equipment.

[0058] In some embodiments of the present invention, the multi-layer composite noise reduction material for insulating oil of the power equipment covers an area of ​​not less than 50% on the inner wall of each side of the oil tank.

[0059] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0060] The raw materials used in the following examples are all commercially available products that can be purchased.

[0061] The preparation method of the cork rubber used in the following examples is as follows: By weight, the cork rubber comprises: 65 parts nitrile rubber, 35 parts cork granules, 1 part Si-69, 4 parts zinc oxide, 1 part stearic acid, 7 parts DOP, 2 parts sulfur, 30 parts carbon black N550, and 1 part DM.

[0062] Step 1: Cork Particle Pretreatment Degreasing treatment: Place the cork particles in an ethanol solution with a concentration of 90-98% and reflux them at 80°C for 5 hours; after treatment, dry them at 100-110°C and a vacuum degree below -0.095 MPa for 2-4 hours to reduce the moisture content to below 5%.

[0063] Activation modification: The dried cork particles were placed in a high-speed mixer, heated to 80°C, and silane coupling agent Si-69 was added. The mixture was stirred at 1000 r / min for 20 minutes to obtain modified cork particles.

[0064] Step 2: Plasticizing and Premixing of Rubber Matrix Plasticizing: Nitrile rubber is plasticized on a two-roll mill at a roller temperature of 50-60℃ until the Mooney viscosity (ML(1+4)100℃) drops to 45, thus obtaining plasticized rubber.

[0065] Premixing: In the plasticized rubber, the activator (zinc oxide, stearic acid), plasticizer (DOP), and reinforcing agent (carbon black N550) are added sequentially and mixed. The reinforcing agent is added in 3 batches, with an interval of 2-3 minutes between each addition, to obtain the premixed rubber.

[0066] Step 3: Compounding of rubber compounds The premixed rubber was transferred to an internal mixer, and the modified cork particles obtained in step 1 were added at 110-120℃ and 50 r / min. The mixture was then mixed for 10 minutes. Subsequently, the rubber compound was discharged to an open mill, cooled to below 100℃, and vulcanizing agent (sulfur) and accelerator (DM) were added. After being mixed evenly, the compound was sheeted and cooled to obtain the composite rubber compound.

[0067] Step 4: Compression molding and vulcanization Compression molding: Place the cooled composite material into the mold, set the pressure to 17 MPa, the temperature to 145℃, and pre-compress for 6 minutes; Vulcanization: Keep the pressure constant and raise the temperature to 165℃. The vulcanization time is 15-20 minutes (adjust according to the product thickness, extend the time by 1 minute for every 1 mm increase in thickness).

[0068] Step 5: Post-processing Post-processing: After vulcanization, the product is taken out and cooled. It is then cooled for 24 hours in an environment of 25±2℃ and 50-60% relative humidity. After that, the edge is trimmed. The trimmed product is placed in a constant temperature and humidity chamber and aged at 70℃ for 72 hours to eliminate internal stress, thus obtaining nitrile cork rubber.

[0069] Transformer oil resistance performance: After compression by 25%, the compression set of the sample after immersion in transformer oil at 125℃ for 168 hours does not exceed 80%; the oil volume change after immersion in transformer oil at 125℃ for 168 hours is controlled within 0 to +10%, and the rubber's oil hardness change value is... 8 to +2 degrees; thickness 6 mm, surface area 65 cm² 2 After the sample was immersed in 800 mL of transformer oil at 100℃ for 164 h, the increase in the transformer oil dielectric loss factor tan δ remained at ≤1%.

[0070] like Figure 3 As shown, the damping coefficient of the cork rubber prepared by this invention is the highest at 50-70℃, according to the test results.

[0071] Example 1 This embodiment provides a multi-layer composite noise reduction material for use in the insulating oil of power equipment, such as... Figure 1As shown, it consists of three parts: a first layer of insulating paperboard 1, cork rubber 2, and a second layer of insulating paperboard 1. Both the first and second layers of insulating paperboard 1 are 5 mm thick. Insulating paperboard 1 is cellulose insulating paper (commercially available product, composition: α-cellulose 92~94wt%, ash content ≤0.1 wt%, moisture ≤6 wt%, power frequency breakdown strength ≥40 kV / mm, longitudinal tensile strength ≥110 MPa, transverse tensile strength ≥85 MPa). Cork rubber 2 is a self-developed cork rubber with optimized service temperature, exhibiting the highest damping peak at 50~70℃. The cork rubber is a cuboid with dimensions of 40 cm x 40 cm and a height of 12 cm. This material can be used for two purposes: as an internal sound-absorbing material and as a vibration-damping material. Before use, it should be soaked in #25 insulating oil for ≥72 h.

[0072] When cork rubber 2 is used as a sound-absorbing material for the inner wall of the oil tank, it adopts a hollow structure with a cavity of 34 cm in diameter and 12 cm in height. The first layer of insulating cardboard 1 faces the tank wall and has a 1 mm diameter hole punched in the center of its diagonal. The second layer of insulating cardboard 1 faces the tank wall and is not perforated. The two layers of insulating cardboard 1 are tightly connected to the cork rubber 2 without gaps. This composite material was tested on a test bench using the transfer function method, and its sound absorption coefficient reached 0.35 at 100 Hz. Verification was performed on a 1000 kV / 240 Mvar reactor prototype, with the cork rubber 2 covering at least 50% of each side of the tank wall, and all four walls were covered. The overall noise reduction of the reactor reached over 3 dB.

[0073] When cork rubber 2 is used as a vibration isolation material for the equipment body, a solid structure is adopted. Figure 2 The two layers of insulating cardboard 1 were not perforated. The vibration isolation rate of this multi-layer composite noise reduction material was tested. The test steps were as follows: Before the test, the multi-layer composite noise reduction material was visually inspected and found to be in good condition. The multi-layer composite noise reduction material was mounted on a fixture, which was rigidly mounted on the vibration table. Two acceleration sensors were installed on the table, and the experiment was conducted using a two-point averaging control method. Vibration test stress was applied to the vertical axis of the multi-layer composite noise reduction material, so that the pressure-bearing surface of the multi-layer composite noise reduction material was subjected to a pressure of 0.8 MPa. The multi-layer composite noise reduction material was kept at 50~55℃ in an oven for 1 h, and a vibration test was conducted with an acceleration of 0.2 g within 10 min. After the test, the appearance of the multi-layer composite noise reduction material was visually inspected, and there was no visible change in the appearance of the multi-layer composite noise reduction material sample compared with before the test. The vibration isolation rate of the multi-layer composite noise reduction material was analyzed according to the following formula.

[0074] Vibration isolation rate = (1 - output level / input level) Tests showed that its minimum vibration isolation rate in the 100-500 Hz range reached 82%.

[0075] Table 1 Parameters of Multilayer Composite Noise Reduction Material in Example 1

[0076] Example 2 This embodiment provides a multi-layer composite noise reduction material for use in the insulating oil of power equipment, such as... Figure 1 As shown, it consists of three parts: a first layer of insulating paperboard 1, cork rubber 2, and a second layer of insulating paperboard 1. Both the first and second layers of insulating paperboard 1 are 5 mm thick. Insulating paperboard 1 is cellulose insulating paper (the same as in Example 1). The cork rubber is a self-developed cork rubber optimized for service temperature, exhibiting the highest damping peak at 50-70°C. The cork rubber 2 part is a cuboid with dimensions of 40 cm x 40 cm and a height of 13 cm. This material can be used for two purposes: as an in-oil sound-absorbing material and as a vibration-damping material. Before use, it should be soaked in #25 insulating oil for ≥72 h.

[0077] When cork rubber 2 is used as a sound-absorbing material for the inner wall of the oil tank, it adopts a hollow structure with a cavity of 30 cm in diameter and 13 cm in height. The first layer of insulating paperboard 1 faces the tank wall and has a 0.9 mm diameter hole punched in the center of its diagonal. The second layer of insulating paperboard 1 faces the tank wall and is not perforated. The two layers of insulating paperboard 1 are tightly connected to the cork rubber 2 without gaps. This composite material was tested on a test bench using the transfer function method, and its sound absorption coefficient reached 0.32 at 100 Hz. Verification was performed on a 1000 kV / 240 Mvar reactor prototype, with the material covering at least 50% of each side of the tank wall, and all four walls, resulting in an overall noise reduction of over 3 dB for the reactor.

[0078] When cork rubber 2 is used as a vibration isolation material for the equipment body, a solid structure is adopted. Figure 2 The two layers of insulating cardboard 1 were not perforated. The vibration isolation rate of this multi-layer composite noise reduction material was tested. The difference between the test method and the vibration isolation rate test in Example 1 was that the material was kept at 50-60℃ in an oven for 1 hour, while the other steps were completely identical. The test results showed that its minimum vibration isolation rate in the 100-500 Hz range reached 86%.

[0079] Table 2 Parameters of Multilayer Composite Noise Reduction Material in Example 2

[0080] Example 3 This embodiment provides a multi-layer composite noise reduction material for use in the insulating oil of power equipment, such as... Figure 1As shown, it consists of three parts: a first layer of insulating paperboard 1, cork rubber 2, and a second layer of insulating paperboard 1. Both the first and second layers of insulating paperboard 1 are 5 mm thick. Insulating paperboard 1 is cellulose insulating paper (the same as in Example 1). Cork rubber 2 is a self-developed cork rubber optimized for service temperature, exhibiting the highest damping peak at 50-70°C. The cork rubber 2 portion is a cuboid with dimensions of 40 cm x 40 cm and a height of 10 cm. This material can be used for two purposes: as an in-oil sound-absorbing material and as a vibration-damping material. Before use, it should be soaked in 25# insulating oil for ≥72 h.

[0081] When cork rubber 2 is used as a sound-absorbing material for the inner wall of the oil tank, it adopts a hollow structure with a diameter of 29 cm and a height of 10 cm. The first layer of insulating paperboard 1 faces the tank body, with a 0.8 mm diameter hole punched at the center of its diagonal. The second layer of insulating paperboard 1 faces the tank wall and is not perforated. The two layers of insulating paperboard 1 are tightly connected to the cork rubber 2 without gaps. This composite material was tested on a test bench using the transfer function method, and its sound absorption coefficient reached 0.34 at 100Hz. Verification was performed on a 1000kV / 240Mvar reactor prototype, with the material covering at least 50% of each side of the tank wall, and all four walls, resulting in an overall noise reduction of over 3dB for the reactor.

[0082] When cork rubber 2 is used as a vibration isolation material for the equipment body, a solid structure is adopted. Figure 2 Both layers of insulating cardboard 1 were left unperforated. The vibration isolation rate of this multi-layer composite noise reduction material was tested using the same method as in Example 2. The test results showed that its minimum vibration isolation rate in the 100-500 Hz range reached 80%.

[0083] Table 3 Parameters of Multilayer Composite Noise Reduction Material in Example 3

[0084] Example 4 This embodiment provides a multi-layer composite noise reduction material for use in the insulating oil of power equipment, such as... Figure 1 As shown, it consists of three parts: a first layer of insulating paperboard 1, cork rubber 2, and a second layer of insulating paperboard 1. Both the first and second layers of insulating paperboard 1 are 5 mm thick. Insulating paperboard 1 is cellulose insulating paper (the same as in Example 1). Cork rubber 2 is a self-developed cork rubber optimized for service temperature, exhibiting the highest damping peak at 50-70°C. The cork rubber 2 portion is a cuboid with dimensions of 40 cm x 40 cm and a height of 12 cm. This material can be used for two purposes: as an in-oil sound-absorbing material and as a vibration-damping material. Before use, it should be soaked in 25# insulating oil for ≥72 hours.

[0085] When cork rubber 2 is used as a sound-absorbing material for the inner wall of the oil tank, it adopts a hollow structure with a diameter of 34 cm and a height of 12 cm. The first layer of insulating paperboard 1 faces the tank wall and has a 1 mm diameter hole punched in the center of its diagonal. The second layer of insulating paperboard 1 faces the tank wall and is not perforated. The two layers of insulating paperboard 1 are tightly connected to the cork rubber 2 without gaps. This composite material was tested on a test bench using the transfer function method, and its sound absorption coefficient reached 0.35 at 100 Hz. Verification was performed on a 1000 kV / 240 Mvar reactor prototype, with the cork rubber 2 covering at least 50% of each side of the tank wall, and all four walls were covered. The overall noise reduction of the reactor reached more than 3 dB.

[0086] When cork rubber 2 is used as a vibration isolation material for the equipment body, a solid structure is adopted. Figure 2 The two layers of insulating cardboard 1 were not perforated. The vibration isolation rate of this multi-layer composite noise reduction material was tested. The difference between the test method and the vibration isolation rate test in Example 1 was that the pressure on the bearing surface of the multi-layer composite noise reduction material was 0.5 MPa, while the other steps were completely identical. The test results showed that its minimum vibration isolation rate in the 100~500 Hz range reached 88%.

[0087] Table 4 Parameters of Multilayer Composite Noise Reduction Material in Example 4

[0088] Example 5 This embodiment provides a multi-layer composite noise reduction material for use in the insulating oil of power equipment, such as... Figure 1 As shown, it consists of three parts: a first layer of insulating paperboard 1, cork rubber 2, and a second layer of insulating paperboard 1. Both the first and second layers of insulating paperboard 1 are 5 mm thick. Insulating paperboard 1 is cellulose insulating paper (the same as in Example 1). Cork rubber 2 is a self-developed cork rubber optimized for service temperature, exhibiting the highest damping peak at 50-70°C. The cork rubber 2 portion is a cuboid with dimensions of 40 cm x 40 cm and a height of 13 cm. This material can be used for two purposes: as an in-oil sound-absorbing material and as a vibration-damping material. Before use, it should be soaked in #25 insulating oil for ≥72 h.

[0089] When cork rubber 2 is used as a sound-absorbing material for the inner wall of the oil tank, it adopts a hollow structure with a cavity of 30 cm in diameter and 13 cm in height. The first layer of insulating paperboard 1 faces the tank body, with a 0.9 mm diameter hole punched at the center of its diagonal. The second layer of insulating paperboard 1 faces the tank wall and is not perforated. The two layers of insulating paperboard 1 are tightly connected to the cork rubber 2 without gaps. This composite material was tested on a test bench using the transfer function method, and its sound absorption coefficient reached 0.32 at 100Hz. Verification was performed on a 1000kV / 240Mvar reactor prototype, with the material covering at least 50% of each side of the tank wall, and all four walls, resulting in an overall noise reduction of over 3dB for the reactor.

[0090] When cork rubber 2 is used as a vibration isolation material for the equipment body, a solid structure is adopted. Figure 2 Both layers of insulating cardboard 1 were not perforated. The vibration isolation rate of this multi-layer composite noise reduction material was tested. The difference between the test method and that in Example 4 was that the material was kept at 55-70℃ in an oven for 1 hour, while the other steps were identical. The test results showed that its minimum vibration isolation rate in the 100-500 Hz range reached 91%.

[0091] Table 5 Parameters of Multilayer Composite Noise Reduction Material in Example 5

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-layer composite noise reduction material for use in insulating oil of power transmission equipment, characterized in that, It consists of cork rubber and insulating cardboard laid at both ends of the cork rubber; An insulating cardboard is laid on the inner wall of the transformer equipment tank, and another insulating cardboard has perforations. The cork rubber has a cavity connected to the perforations.

2. The multi-layer composite noise reduction material for use in insulating oil of power equipment as described in claim 1, characterized in that, The insulating paperboard includes any one of the following: hot-dip galvanized carbon steel plate, stainless steel plate, basalt fiber felt, glass wool fiber felt, constraint damping sound insulation board, and cellulose insulating paper.

3. The multi-layer composite noise reduction material for use in insulating oil of power equipment as described in claim 1, characterized in that, The cork rubber is nitrile-based cork rubber, which has the highest damping peak at 50~70℃.

4. The multi-layer composite noise reduction material for use in insulating oil of power equipment as described in claim 1, characterized in that, The insulating paperboard has the same shape as the cork rubber end face, with a thickness of 4-6 mm and a cork rubber height of 10-13 cm. The cavity is a cylindrical cavity with the same height as the cork rubber. The perforation is located at the center of the insulating cardboard. The diameter of the perforation is 0.8-1.1 mm.

5. The multi-layer composite noise reduction material for use in insulating oil of power equipment as described in claim 4, characterized in that, The thickness of the insulating paperboard is 4-6 mm; the length and width of the cork rubber are equal, 38-42 cm, and the height is 10-13 cm; the diameter of the cavity is 30-34 cm.

6. The multi-layer composite noise reduction material for use in insulating oil of power equipment as described in claim 4, characterized in that, The insulating paperboard is 5 mm thick; the cork rubber is 40 cm long and 12 cm high; the cavity is 34 cm in diameter and 12 cm high; and the perforation is 1 mm in diameter. Alternatively, the insulating paperboard has a thickness of 5 mm, the cork rubber has equal length and width of 40 cm and a height of 13 cm; the cavity has a diameter of 30 cm and a height of 13 cm; and the perforation has a diameter of 0.9 mm. Alternatively, the insulating paperboard has a thickness of 5 mm, the cork rubber has equal length and width of 40 cm and a height of 10 cm, the cavity has a diameter of 29 cm and a height of 10 cm, and the perforation has a diameter of 0.8 mm.

7. The multi-layer composite noise reduction material for use in insulating oil of power equipment as described in claim 1, characterized in that, The method for preparing the cork rubber is as follows: The cork rubber comprises, by weight, 60-70 parts of nitrile rubber, 30-40 parts of cork particles, 0.8-1.2 parts of silane coupling agent, 4-7 parts of activator, 5-10 parts of plasticizer, 2 parts of vulcanizing agent, 25-40 parts of reinforcing agent, and 0.5-1.5 parts of accelerator. After degreasing, cork particles are mixed with a silane coupling agent to obtain modified cork particles; Nitrile rubber is plasticized and compounded to obtain a premixed rubber; Modified cork particles were added to the premixed adhesive and then mixed to obtain a composite adhesive. The composite rubber compound is molded, vulcanized, and left to stand to obtain cork rubber.

8. The application of the multilayer composite noise reduction material for use in the insulating oil of power equipment as described in any one of claims 1-7 in noise reduction of power equipment.

9. A reactor, characterized in that, The inner wall of the reactor's oil tank is provided with a multi-layer composite noise reduction material for use in the insulating oil of power equipment as described in any one of claims 1-7.

10. The reactor as described in claim 9, characterized in that, The multi-layer composite noise reduction material used in the insulating oil of the power equipment shall cover an area of ​​not less than 50% on the inner wall of each side of the oil tank.

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