Dampproof treatment method for transformer body

Abstract

The invention relates to the technical field of transformers, in particular to a transformer body moisture-proof treatment method which comprises the steps that hydrophobic insulating oil containing specific active ingredients is pumped into a vacuum tank; dipping under micro-negative pressure and temperature control conditions to drive the active components to deeply permeate and adsorb; then, through extremely slow controlled pressure release, gradient distribution of hydrophobic components gradually decreasing from the inside of the insulating material to the outside is formed by utilizing a fluid dynamics principle; and finally, discharging the insulating oil, introducing high-temperature dry nitrogen carrying a gas-phase hydrophobic film forming medium, and depositing on the treated surface and all internal cavities to form a compact chemical film. According to the method, through cooperation of in-situ gradient construction and gas-phase integral film forming, three-dimensional and long-acting moisture prevention from a material body to a space surface is achieved, and the protection effect is uniform and reliable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transformers, in particular to a body moisture-proof treatment method of a transformer. BACKGROUND

[0002] In the manufacturing process of power transformers, ensuring the long-term dryness and moisture resistance of the internal insulation system is the core of guaranteeing the safe and stable operation of the equipment for decades. The body of the transformer is composed of a large number of cellulose insulation materials wrapped around the winding and the core, such as insulating paper board and crepe paper. These cellulose insulation materials are inherently hydrophilic. The presence of moisture can sharply reduce the insulation strength, accelerate material aging, and possibly cause discharge failure. Therefore, the production process includes a key process of deep drying of the body - vacuum hot oil drying; after the process is completed, the body is in the best state: the internal moisture is removed to the maximum extent, and the insulation material pores are kept open due to the residual temperature. However, the existing subsequent process is to release the vacuum after drying, hoist the warm body out of the vacuum tank, and then perform final assembly, detection, and finally factory oiling. This process has a significant quality defect: the warm body after drying is hoisted out of the vacuum tank and exposed to the workshop environment for subsequent assembly and detection, which will cause the body to rapidly absorb moisture from the air, seriously weakening the drying effect. SUMMARY

[0003] Therefore, the purpose of the present application is to overcome the problem of exposure and moisture absorption of the transformer body after vacuum hot oil drying in the prior art, and to provide a body moisture-proof treatment method of a transformer. In the best drying window period of the insulation material state, the method realizes long-term and three-dimensional moisture-proof from the insulation material body to the internal cavity surface by combining in-situ gradient impregnation and gas phase film formation, thereby eliminating the moisture absorption risk and greatly improving the uniformity and reliability of the protection.

[0004] To solve the above technical problems, the present application provides a body moisture-proof treatment method of a transformer for processing the body of the transformer. The method is performed after vacuum hot oil drying of the body of the transformer. The method comprises the following steps: Step one: after the vacuum hot oil drying of the body of the transformer is released from the vacuum in the vacuum tank, 50-65℃ hydrophobic insulating oil is pumped into the vacuum tank; the hydrophobic insulating oil comprises transformer oil and hydrophobic active ingredients dissolved therein; Step two: after the hydrophobic insulating oil immerses the body of the transformer, the pressure of the vacuum tank is adjusted to-0.06MPa to-0.03MPa, and the body of the transformer is immersed in the hydrophobic insulating oil under the pressure; Step three: after reaching the set immersion time, the temperature of the hydrophobic insulating oil is kept unchanged, and dry air is introduced into the vacuum tank at a speed of less than 0.01MPa / min until normal pressure is reached; Step 4: Drain the hydrophobic insulating oil, and then introduce dry nitrogen gas at 80℃~100℃ into the vacuum tank to obtain the transformer body after moisture-proof treatment; wherein, the dry nitrogen gas carries a gaseous hydrophobic film-forming medium.

[0005] Preferably, the hydrophobic active ingredient comprises a mixture of amino silicone oil and fluorinated hydrophobic agent, and the weight ratio of amino silicone oil to fluorinated hydrophobic agent is 1:1 to 3:1; The method for preparing the hydrophobic insulating oil includes: heating the transformer oil to 58°C to 62°C, adding the hydrophobic active ingredient to the transformer oil under stirring conditions, and obtaining the hydrophobic insulating oil; wherein the weight of the hydrophobic active ingredient is 2% to 8% of the transformer oil.

[0006] Preferably, the fluorinated hydrophobic agent comprises fluorocarbon-modified polysiloxane.

[0007] Preferably, the fluorinated hydrophobic agent includes any one of fluorinated acrylates, perfluoropolyethers, and fluorocarbon surfactants.

[0008] Preferably, when pumping hydrophobic insulating oil at 50°C to 65°C into the vacuum tank, residual process hot oil in the transformer body is simultaneously discharged. This includes: controlling the flow rate of the hydrophobic insulating oil pumped in to be equal to the flow rate of the residual process hot oil discharged; and based on the pressure balance of the fluid, causing the hydrophobic insulating oil to enter from the bottom of the vacuum tank and rise, while the residual process hot oil is displaced and discharged from the bottom of the vacuum tank.

[0009] Preferably, the process of introducing dry nitrogen gas at 80°C to 100°C into the vacuum tank after the hydrophobic insulating oil has been discharged includes: injecting a gaseous hydrophobic film-forming medium into the dry nitrogen gas at 80°C to 100°C to obtain a film-forming reaction gas; wherein the gaseous hydrophobic film-forming medium includes vaporized alkoxysilane; introducing the film-forming reaction gas into the vacuum tank and monitoring the concentration of the alkoxysilane; and stopping the injection of the gaseous hydrophobic film-forming medium when the concentration of the alkoxysilane stabilizes.

[0010] Preferably, the process of introducing dry nitrogen gas at 80°C to 100°C into the vacuum tank further includes: adjusting the pressure inside the vacuum tank in a pulse manner according to a set interval period, with the pressure adjustment range being ±1kPa to ±15kPa.

[0011] Preferably, before injecting the gaseous hydrophobic film-forming medium into the dry nitrogen gas at a temperature of 80℃~100℃, the method further includes: measuring the concentration of alkoxysilane in the film-forming reaction gas to obtain the actual concentration; comparing the actual concentration with the target concentration, adjusting the injection rate of the gaseous hydrophobic film-forming medium according to the comparison result until the actual concentration falls within the range of the target concentration to obtain the calibrated film-forming reaction gas; and introducing the calibrated film-forming reaction gas into the vacuum tank.

[0012] Preferably, adjusting the injection rate of the vapor-phase hydrophobic film-forming medium according to the comparison results until the actual concentration falls within the target concentration range includes: setting an initial injection rate of the vapor-phase hydrophobic film-forming medium based on the median of the target concentration range and the flow rate of the dry nitrogen; continuously measuring the actual concentration and calculating the deviation between the actual concentration and the median of the target concentration range; adjusting the initial injection rate based on a differentiated adjustment strategy according to the absolute value of the deviation: if the absolute value of the deviation is greater than a first threshold, the initial injection rate is adjusted by a first adjustment amplitude; if the absolute value of the deviation is less than or equal to the first threshold but greater than a second threshold, the initial injection rate is adjusted by a second adjustment amplitude; if the absolute value of the deviation is less than or equal to the second threshold, the initial injection rate is maintained; wherein, the first threshold is greater than the second threshold, and the second adjustment amplitude is less than the first adjustment amplitude.

[0013] Preferably, when dry nitrogen gas at 80°C to 100°C is introduced into the vacuum tank, the gas is introduced simultaneously through at least two air inlets located at the bottom, middle and top of the vacuum tank, and led out from the air outlet on the other side symmetrical to the air inlets.

[0014] Compared with the prior art, the above-described technical solution of the present invention has the following advantages: The transformer body moisture-proof treatment method of the present invention achieves long-term, three-dimensional moisture-proofing from the insulation material body to the surface of the internal cavity by combining in-situ gradient impregnation and vapor phase film formation within the window period after the insulation material is in the best condition. This eliminates the risk of moisture regain and greatly improves the uniformity and reliability of the protection. Attached Figure Description

[0015] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0016] Figure 1 This is a flowchart of a preferred embodiment of the transformer body moisture-proofing treatment method. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0018] Reference Figure 1 As shown, this embodiment of the invention provides a method for moisture-proofing the transformer body, used to treat the transformer body. The transformer body undergoes vacuum hot oil drying in a vacuum tank and remains in the vacuum tank after the vacuum has been released, reusing the residual heat and sealed environment of the vacuum tank. It should be noted that vacuum hot oil drying is a powerful dehydration process. The high temperature causes the bound water in the insulating cellulose material to gain energy and escape, while the continuous high vacuum provides the driving force for escape, drawing water vapor from deep within the material. This process is equivalent to deep pore expansion of the material. When drying is completed, the pores occupied by moisture are emptied, and because the material is still in a state of thermal expansion under residual temperature, these pore channels are at their maximum opening.

[0019] The moisture-proof treatment method of this invention occurs after the transformer body has finished vacuum hot oil drying in a vacuum tank and the vacuum has been released, and includes the following steps performed in sequence: Step 1: Pump hydrophobic insulating oil at 50℃~65℃ into the vacuum tank. The hydrophobic insulating oil includes transformer oil and hydrophobic active ingredients dissolved within it. This step directly follows the vacuum hot oil drying process. Utilizing the residual heat and sealed environment within the vacuum tank, the temperature-controlled hydrophobic insulating oil is pumped in, allowing it to penetrate the deepest and finest pores with minimal flow resistance. Furthermore, the drying process not only removes moisture but also other volatile impurities adsorbed on the material surface. The polar groups, primarily hydroxyl groups, on the cellulose surface are fully exposed, resulting in high surface energy and an adsorption-starved state. When the warm hydrophobic active ingredient molecules come into contact with the high-energy surface, strong physical adsorption occurs, providing a foundation for the subsequent formation of a robust gradient adsorption layer and chemically bonded film.

[0020] Specifically, transformer oil refers to mineral oil specifically used for transformer insulation and cooling. The hydrophobic active ingredient includes a mixture of amino silicone oil and a fluorinated hydrophobic agent, with a weight ratio of amino silicone oil to fluorinated hydrophobic agent of 1:1 to 3:1. In a preferred embodiment of the invention, the fluorinated hydrophobic agent is preferably a fluorocarbon-modified polysiloxane. The amino groups in the amino silicone oil molecule have a strong affinity and reactivity for the hydroxyl groups on the cellulose surface, making them easy to adsorb and anchor. The fluorocarbon-modified polysiloxane simultaneously possesses the flexibility and compatibility of the siloxane skeleton, as well as the extremely low surface energy of the fluorocarbon segments. The amino silicone oil and fluorocarbon-modified polysiloxane work synergistically; the amino silicone oil preferentially adsorbs onto the material surface and pore walls, while the fluorocarbon segments, acting as hydrophobic synergists, are arranged on the outermost layer, providing superior hydrophobic and oleophobic properties compared to simple alkyl chains, resulting in a more robust and hydrophobic protective layer. Furthermore, due to the chemical inertness of the fluorocarbon chains, its aging resistance is superior. It should be noted that fluorocarbon-modified polysiloxanes are polymers formed by grafting fluorocarbon groups (e.g., -CF3) onto the polysiloxane backbone through chemical methods.

[0021] In one preferred embodiment, the weight ratio of amino silicone oil to fluorocarbon modified polysiloxane is preferably 2:1. This weight ratio of hydrophobic active ingredients ensures that the superhydrophobic advantages of fluorocarbon materials are maximized under the premise of good anchoring.

[0022] Step Two: After the hydrophobic insulating oil has submerged the transformer, close the valve and evacuate the vacuum tank to a pressure of -0.06MPa to -0.03MPa, maintaining this pressure while controlling the temperature of the hydrophobic insulating oil at 55℃ to 60℃. Immerse the transformer under these conditions for 60 to 180 minutes. This step utilizes the synergistic effect of slight negative pressure and a specific medium temperature to drive the hydrophobic active components to penetrate deeply into the insulating material. The slight negative pressure creates an attraction force into the pores of the insulating material, driving the insulating oil containing the hydrophobic active components to penetrate deeply into the material. At a temperature of 55℃ to 60℃, the thermal motion of the hydrophobic active molecules intensifies, making them more easily adsorbed onto the inner walls of the pores. This lays the material distribution foundation for the subsequent formation of a gradient structure, solving the problems of insufficient immersion depth and weak adsorption.

[0023] It should be noted that -0.06MPa to -0.03MPa is the verified optimal pressure range. If the pressure is too low, close to -0.1MPa, the insulating oil will boil violently and damage the insulation. If the pressure is too high, close to -0.02MPa, the penetration driving force will be insufficient. -0.06MPa to -0.03MPa can provide effective driving force while ensuring process safety.

[0024] Step 3: After impregnation, maintain the temperature of the hydrophobic insulating oil constant and introduce dry air into the vacuum tank at a rate of less than 0.01 MPa / min until atmospheric pressure is reached. This step is crucial for forming the gradient structure. During the dynamic equilibrium process of slow pressure recovery, the hydrophobic insulating oil in the surface layer, shallow pores, and large pores of the insulating material preferentially flows back due to pressure. Active components that have penetrated into the deep micropores and adhered to the pore walls are effectively retained due to capillary forces and adsorption. This process ultimately results in a continuous distribution of hydrophobic active components across the cross-section of the insulating material, with the concentration gradually decreasing from the inside out. When ambient moisture intrudes from the outside, it first encounters the relatively weaker hydrophobic surface layer, which still effectively hinders rapid moisture penetration. The deeper the moisture penetrates, the greater the hydrophobic resistance it encounters. This gradient structure avoids the problems of material embrittlement or decreased compatibility with transformer oil that may result from a single high-concentration treatment.

[0025] It should be noted that a pressure release rate of less than 0.01 MPa / min is crucial for forming an effective concentration gradient. If the rate is too fast, the insulating oil will be released uniformly, and a gradient cannot be formed. This limit ensures the effective retention of deeply adsorbed molecules.

[0026] Step 4: The hydrophobic insulating oil is discharged from the vacuum tank, and then dry nitrogen gas at 80℃~100℃ is introduced into the vacuum tank to obtain a moisture-proof transformer body. The dry nitrogen gas carries a gaseous hydrophobic film-forming medium. The preferred gaseous hydrophobic film-forming medium is an alkoxysilane, which undergoes hydrolysis-condensation reaction at high temperatures to form a siloxane network film on the substrate. The dry nitrogen gas acts as a carrier and provides the reaction environment, preventing moisture from interfering with the gaseous deposition reaction. This step utilizes the pervasive diffusion characteristics of the gaseous medium to cover all complex internal cavities and material surfaces, including the narrowest gaps between windings, the rough surfaces of insulating paperboard, and the complex structure of the iron core. The dry nitrogen gas at 80℃~100℃ provides the activation energy for the reaction. When the gaseous medium molecules come into contact with various solid surfaces, whether treated in the first stage or untreated, hydrolysis and condensation reactions occur, anchoring them to the substrate through chemical bonds to form a chemically bonded hydrophobic polymer network film.

[0027] Ultimately, through the first-level gradient hydrophobic treatment and the second-level vapor phase film formation, moisture, whether slowly seeping in through the internal capillaries of the insulating material or directly condensing on the surface of the complex structure, forms an effective barrier, achieving long-lasting, three-dimensional moisture protection from the insulating material itself to the surface of the internal cavity, thereby eliminating the risk of moisture regain and significantly improving the uniformity and reliability of protection.

[0028] Furthermore, the weight of the hydrophobic active ingredient is 2% to 8% of the transformer oil, within which it can effectively form a gradient and film layer; preferably 4.5%.

[0029] In this embodiment of the invention, before pumping the hydrophobic insulating oil into the vacuum tank, the hydrophobic insulating oil is prepared, homogenized, and preheated. The preparation method of the hydrophobic insulating oil includes: heating transformer oil to 58°C~62°C, and adding hydrophobic active ingredients to the transformer oil under stirring to obtain the hydrophobic insulating oil. The temperature for preparing the hydrophobic insulating oil is slightly higher than the lower limit of the temperature in step one. At this temperature, the viscosity of the transformer oil is significantly reduced, and the fluidity is enhanced, which is conducive to the diffusion and dissolution of the active ingredients and avoids the formation of local high-concentration colloids; at the same time, this temperature will not cause rapid thermal aging of the insulating oil or the active ingredients.

[0030] In other embodiments, the fluorinated hydrophobic agent may also be any one of fluorinated acrylates, perfluoropolyethers, and fluorocarbon surfactants.

[0031] Based on the above embodiments, when pumping hydrophobic insulating oil at 50°C~65°C into the vacuum tank, residual process hot oil in the transformer body is simultaneously discharged. This includes: controlling the flow rate of the pumped hydrophobic insulating oil to be equal to the flow rate of the discharged residual process hot oil; and based on the pressure balance of the fluid, allowing the hydrophobic insulating oil to enter from the bottom of the vacuum tank and rise, while the residual process hot oil is replaced and discharged from the bottom of the vacuum tank.

[0032] Process hot oil refers to the transformer oil used for heating and dehydration in the vacuum hot oil drying process and remaining in the vacuum tank and transformer body. At the end of the vacuum hot oil drying process, most of the process hot oil in the tank is drained back to the storage tank through the drain valve at the bottom of the vacuum tank. However, no matter how thoroughly the oil is drained, a considerable amount of oil will remain inside the transformer body, at the bottom of the vacuum tank, in dead corners of the pipelines, and in the bottom space between the transformer body and the tank. This portion of oil, which cannot be completely drained by gravity, is the residual process hot oil that needs to be replaced. The residual old oil mixes with the newly pumped hydrophobic insulating oil, severely diluting the hydrophobic active components and causing their concentration to fall below the design value, resulting in treatment failure. Furthermore, the residual process hot oil occupies the pores of the insulating material, forming a barrier that prevents the penetration of insulating oil containing active components, thus hindering deep treatment.

[0033] During the implementation process, it was confirmed that the oil inlet and outlet valves at the bottom of the vacuum tank were unobstructed and connected to the hydrophobic insulating oil storage tank and the waste hot oil collection tank, respectively. Both pipelines were equipped with high-precision mass flow meters and regulating valves. The hydrophobic insulating oil transfer pump was started, and the outlet valve was simultaneously opened to a predetermined degree. When the pump inflow and outflow were measured to be consistent, the operator could see through the observation window that the pale yellow hydrophobic insulating oil entered from the bottom of the tank, and the liquid level inside the tank rose steadily. In the sight glass of the outlet pipe, initially, the outflowing oil was a darker-colored residual hot process oil. After about 30 minutes, the color of the outflowing oil began to lighten and become clearer. When the reading of the online dielectric constant meter stabilized at the characteristic value of the new oil, the replacement was considered complete. The outlet valve was then closed. At this point, the vacuum tank was completely filled with hydrophobic insulating oil at a temperature of approximately 60°C and a defined concentration, and the liquid level had submerged the tank body.

[0034] In this embodiment, the pumping of hydrophobic insulating oil and the discharge of residual hot process oil are carried out simultaneously. Compared to the method of first discharging the residual hot process oil and then pumping in the hydrophobic insulating oil, this avoids the problems of fluid impact and air bubble entrainment. The reasoning is as follows: If oil is discharged first and then pumped in, the flowing oil will carry air, generating air bubbles inside the tank. These bubbles may be forced into the deep pores of the insulating material, forming air pockets that are difficult to expel. These air pockets will become a fatal barrier to the subsequent penetration of the hydrophobic insulating oil, leading to complete failure of the local treatment. By using simultaneous equal-flow displacement, the total liquid volume inside the tank remains constant, the liquid level rises smoothly and slowly, and the fluid movement is dominated by laminar flow, resulting in minimal impact on the reactor body. Since the oil drain is also open at the bottom, no large pressure difference is formed within the system to draw in air, resulting in a very stable fluid dynamic environment and effectively avoiding turbulence and the generation and entrainment of air bubbles.

[0035] After the immersion treatment with hydrophobic insulating oil is completed, the transformer body has hydrophobicity from the inside out. However, for the extremely complex geometric space inside the transformer body, such as the narrow gaps between windings, the sharp back of the insulating parts, the surface of metal components, and the outermost pores of the material itself, the liquid medium is difficult to achieve uniform coverage due to surface tension, capillary action and flow dead angles, resulting in local protection blind spots.

[0036] To address this issue, the present invention proposes a method to generate a solid protective film on the surface of a device by vaporizing a hydrophobic film-forming medium and mixing it with a carrier gas under controlled conditions. This method includes: injecting a gaseous hydrophobic film-forming medium into dry nitrogen gas at a temperature of 80°C to 100°C to obtain a film-forming reaction gas; wherein the gaseous hydrophobic film-forming medium includes vaporized alkoxysilane; passing the film-forming reaction gas into a vacuum tank and monitoring the concentration of alkoxysilane; and stopping the injection of the gaseous hydrophobic film-forming medium once the concentration of alkoxysilane has stabilized.

[0037] In practice, the dry nitrogen gas used as the carrier gas is heated to 80℃~100℃ to provide activation energy for the reaction and to maintain the temperature of the reactor body, preventing the condensation of residual solvent inside due to cooling. Alkoxysilanes, including methyltrimethoxysilane and octyltriethoxysilane, are liquids at room temperature. They are converted into a gaseous phase through a vaporization device and injected into the hot nitrogen gas stream at a controllable flow rate, forming a uniform film-forming reaction gas. At high temperatures, the alkoxysilanes undergo hydrolysis and condensation reactions with the substrate surface, forming a network structure linked by -Si-O-Si- covalent bonds, and chemically bonded to the substrate (Si-O-substrate). This film is no longer a physical adhesion but rather grows on the substrate, exhibiting excellent adhesion, wear resistance, and long-term chemical stability.

[0038] The film-forming reaction gas is continuously introduced into the vacuum chamber, contacting the chamber surface. Alkoxysilane monomers are adsorbed and react on the chamber surface. Initially, due to the large amount of adsorption of alkoxysilane monomers on the chamber surface, the gas concentration continuously decreases. As the surface is gradually covered, the adsorption sites decrease, the reaction tends to saturate, and the gas concentration gradually rises and eventually stabilizes. The film-forming process reaches dynamic equilibrium, at which point the injection of the hydrophobic film-forming medium is stopped. For monitoring, a circulation pipeline is used to draw gas from the vacuum chamber outlet, and the concentration of alkoxysilanes in the gas is detected by gas chromatography.

[0039] In the vapor-phase film deposition process described above, for large, complex transformer bodies, even with the introduction of circulating reactant gas, problems such as gas diffusion dead zones or differences in surface adsorption saturation may still arise. Surfaces in dead zones experience slow reactant gas concentration renewal, resulting in a film deposition rate far lower than in the mainstream areas, ultimately leading to uneven film thickness or even incomplete local film formation. Furthermore, vapor-phase deposition relies on the adsorption of monomer molecules on the surface. In the initial stage, all surfaces adsorb molecules, consuming gaseous monomers. However, due to differences in airflow and structure, adsorption rates vary at different locations, potentially leading to a false impression of local adsorption saturation. Under stable airflow conditions, this difference is difficult to self-regulate.

[0040] To address this issue and ensure the uniformity, integrity, and consistency of vapor-phase film formation across the entire geometric surface of the vessel, this invention introduces pulsed pressure regulation. Specifically, during the process of introducing dry nitrogen gas at 80°C to 100°C into the vacuum vessel, the pressure inside the vacuum vessel is pulsed and adjusted according to a set interval period, with the pressure adjustment range being ±1 kPa to ±15 kPa.

[0041] In a specific implementation plan, pressure is applied at regular intervals, such as every 15-20 minutes. This cycle is much longer than the duration of a single pulse, typically not exceeding one minute, ensuring that the system has sufficient time to recover a stable cycle between pulses and to perform effective concentration monitoring. A small amount of gas is injected into or extracted from the vacuum tank in a very short time by rapidly operating a solenoid valve on a small high-pressure gas cylinder connected to the vacuum tank, causing a rapid change in the tank's pressure. A preferred implementation is to perform this operation through a separate pressure pulsation branch while maintaining the main circulation gas circuit valve opening unchanged. For example, this could involve rapidly opening the valve connected to a high-pressure nitrogen cylinder for instantaneous gas replenishment, or rapidly opening the valve connected to a small vacuum tank for instantaneous gas extraction.

[0042] When a pressure pulse is applied, the problems of dead zones and inhomogeneity are addressed together: at the moment of the positive pressure pulse, the overall pressure inside the tank increases, and the high-pressure gas is forced to penetrate into all possible spaces, including those dead zones with low flow rates; during the subsequent negative pressure pulse or pressure recovery period, the gas is extracted from these areas. This push and pull creates a forced replacement and renewal of the gas in the dead zones, bringing in new reactive gas and removing the old gas that has been exhausted. This significantly improves the mass transfer efficiency of the reactive gas inside the complex structure, ensuring that all surfaces can continuously obtain sufficient reactive monomers, and making the film growth rate tend to be uniform.

[0043] In addition, rapid pressure fluctuations create a slight shearing or perturbation effect on the monomer molecules already adsorbed on the surface. This helps to desorb molecules that are weakly bound or in suboptimal positions, making room for new, more reactive molecules to adsorb, promoting the dynamic renewal of surface reaction sites, and contributing to the formation of a denser and more uniform film structure, thereby improving the quality and binding strength of the film.

[0044] To further address the problem of gas diffusion dead zones, in this embodiment of the invention, when dry nitrogen gas at 80°C to 100°C is introduced into the vacuum tank, the gas is simultaneously introduced through at least two inlets located at the bottom, middle, and top of the vacuum tank, and exited from an outlet on the opposite side symmetrical to the inlets.

[0045] In a specific implementation, at least two, preferably three, air inlets are provided vertically on the vacuum tank shell, respectively from the bottom, middle, and top. These inlets are connected to the main gas supply system via distribution pipelines and can be independently controlled by valves. During gas phase processing, at least two air inlets at different heights are opened simultaneously to inject high-temperature dry nitrogen (or film-forming reaction gas) into the tank from multiple spatial locations, breaking down temperature stratification and creating a multi-directional driving force.

[0046] The air outlets are spatially staggered from the air inlets, typically positioned at a corresponding height on the opposite side of the tank. For example, when air enters from the bottom, middle, or top on the left side, the air outlets can be positioned at the corresponding locations on the right side. This side-in / side-out or diagonal flow layout creates a horizontal through-flow. The symmetrically arranged air outlets can evenly collect the gases flowing in from each inlet and passing through the reaction, preventing waste gas from accumulating in any particular area.

[0047] Furthermore, before injecting the gaseous hydrophobic film-forming medium into dry nitrogen gas at a temperature of 80℃~100℃, the process includes: measuring the concentration of alkoxysilane in the film-forming reaction gas to obtain the actual concentration; comparing the actual concentration with the target concentration, adjusting the injection rate of the gaseous hydrophobic film-forming medium according to the comparison result until the actual concentration falls within the range of the target concentration to obtain the calibrated film-forming reaction gas; and introducing the calibrated film-forming reaction gas into a vacuum tank.

[0048] In the specific implementation plan, a bypass sampling gas flow is drawn from the pipeline downstream of the injection point and before the gas enters the vacuum tank. This gas flow is introduced into an online concentration analyzer, preferably a Fourier transform infrared spectrometer, to measure the absorption intensity of the characteristic functional groups of alkoxysilanes. This intensity is proportional to the concentration of alkoxysilane monomers in the gas. The instrument outputs an electrical signal representing the actual concentration of alkoxysilanes in real time. The control system internally presets a target concentration range and continuously compares the measured actual concentration with the target value to calculate the deviation. Based on the magnitude and direction of the deviation, the system issues commands to adjust the actuator of the alkoxysilane vaporization injection unit, such as changing the speed of the metering pump or adjusting the flow rate of the carrier gas. If the actual concentration is lower than the target range, the injection rate is increased proportionally; if the actual concentration is higher than the target range, the injection rate is decreased proportionally. After calibration, the valve is switched to cut the gas flow from the calibration loop to the main reaction loop leading to the vacuum tank.

[0049] To achieve rapid and stable control of alkoxysilane concentration, this invention provides a differential adjustment strategy based on deviation grading, comprising: setting an initial injection rate of the gas-phase hydrophobic film-forming medium based on the median of the target concentration range and the flow rate of dry nitrogen; continuously measuring the actual concentration and calculating the deviation between the actual concentration and the median of the target concentration range; adjusting the initial injection rate according to the absolute value of the deviation based on the differential adjustment strategy: if the absolute value of the deviation is greater than a first threshold, the initial injection rate is adjusted by a first adjustment amplitude; if the absolute value of the deviation is less than or equal to the first threshold but greater than a second threshold, the initial injection rate is adjusted by a second adjustment amplitude; if the absolute value of the deviation is less than or equal to the second threshold, the initial injection rate is maintained; wherein the first threshold is greater than the second threshold, and the second adjustment amplitude is less than the first adjustment amplitude. The control logic of this scheme is: fast adjustment when the deviation is large; fine adjustment when the deviation is small; and continued observation when approaching the target.

[0050] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for moisture-proofing the transformer body, used to treat the transformer body, characterized in that... This method is performed after the transformer body has undergone vacuum hot oil drying, and the treatment method includes: Step 1: After the transformer body is dried in a vacuum tank with hot oil to remove the vacuum, a hydrophobic insulating oil at 50℃~65℃ is pumped into the vacuum tank; the hydrophobic insulating oil includes transformer oil and hydrophobic active ingredients dissolved therein; Step 2: After the transformer body is submerged in the hydrophobic insulating oil, the pressure of the vacuum tank is adjusted to -0.06MPa to -0.03MPa, and the transformer body is submerged in the hydrophobic insulating oil under this pressure; Step 3: After the set immersion time is reached, keep the temperature of the hydrophobic insulating oil constant and introduce dry air into the vacuum tank at a rate of less than 0.01 MPa / min until atmospheric pressure is reached; Step 4: Drain the hydrophobic insulating oil, and then introduce dry nitrogen gas at 80℃~100℃ into the vacuum tank to obtain the transformer body after moisture-proof treatment; wherein, the dry nitrogen gas carries a gaseous hydrophobic film-forming medium.

2. The method for moisture-proofing the transformer body according to claim 1, characterized in that... The hydrophobic active ingredient comprises a mixture of amino silicone oil and fluorinated hydrophobic agent, wherein the weight ratio of amino silicone oil to fluorinated hydrophobic agent is 1:1 to 3:

1. The method for preparing the hydrophobic insulating oil includes: heating the transformer oil to 58°C to 62°C, adding the hydrophobic active ingredient to the transformer oil under stirring conditions, and obtaining the hydrophobic insulating oil; wherein the weight of the hydrophobic active ingredient is 2% to 8% of the transformer oil.

3. The method for moisture-proofing the transformer body according to claim 2, characterized in that... The fluorinated hydrophobic agent includes fluorocarbon-modified polysiloxane.

4. The method for moisture-proofing the transformer body according to claim 2, characterized in that... The fluorinated hydrophobic agent includes any one of fluorinated acrylates, perfluoropolyethers, and fluorocarbon surfactants.

5. The method for moisture-proofing the transformer body according to claim 2, characterized in that... In step one, when hydrophobic insulating oil at 50℃~65℃ is pumped into the vacuum tank, residual hot process oil inside the transformer body is simultaneously discharged, including: The flow rate of the hydrophobic insulating oil pumped into the system is controlled to be equal to the flow rate of the residual hot process oil discharged from the system. The hydrophobic insulating oil enters and rises from the bottom of the vacuum tank based on the pressure balance of the fluid, while the residual hot process oil is displaced and discharged from the bottom of the vacuum tank.

6. The method for moisture-proofing the transformer body according to claim 1, characterized in that... In step four, after the hydrophobic insulating oil is discharged, dry nitrogen gas at 80°C~100°C is introduced into the vacuum container, including: A gaseous hydrophobic film-forming medium is injected into the dry nitrogen gas at a temperature of 80℃~100℃ to obtain a film-forming reaction gas; wherein, the gaseous hydrophobic film-forming medium includes vaporized alkoxysilane. The film-forming reaction gas is introduced into the vacuum vessel, and the concentration of the alkoxysilane is monitored; Once the concentration of the alkoxysilane stabilizes, the injection of the vapor-phase hydrophobic film-forming medium is stopped.

7. The method for moisture-proofing the transformer body according to claim 1 or 6, characterized in that... The process of introducing dry nitrogen gas at 80°C to 100°C into the vacuum tank also includes: adjusting the pressure inside the vacuum tank in a pulse manner according to a set interval period, with the pressure adjustment range being ±1kPa to ±15kPa.

8. The method for moisture-proofing the transformer body according to claim 6, characterized in that... Before injecting the gaseous hydrophobic film-forming medium into the dry nitrogen gas at a temperature of 80℃~100℃, the process further includes: The concentration of alkoxysilane in the film-forming reaction gas was measured to obtain the actual concentration; The actual concentration is compared with the target concentration, and the injection rate of the gas-phase hydrophobic film-forming medium is adjusted according to the comparison result until the actual concentration falls within the range of the target concentration, thereby obtaining the calibrated film-forming reaction gas. The calibrated film-forming reaction gas is introduced into the vacuum vessel.

9. The method for moisture-proofing the transformer body according to claim 8, characterized in that... Adjusting the injection rate of the vapor-phase hydrophobic film-forming medium based on the comparison results until the actual concentration falls within the target concentration range includes: Based on the median of the target concentration range and the flow rate of the dry nitrogen, the initial injection rate of the gas-phase hydrophobic film-forming medium is set. The actual concentration is continuously measured, and the deviation between the actual concentration and the midpoint of the target concentration range is calculated. Based on the absolute value of the deviation, the initial injection rate is adjusted using a differentiated adjustment strategy: If the absolute value of the deviation is greater than the first threshold, the initial injection rate is adjusted by a first adjustment range; If the absolute value of the deviation is less than or equal to the first threshold and greater than the second threshold, the initial injection rate is adjusted by the second adjustment range. If the absolute value of the deviation is less than or equal to the second threshold, then the initial injection rate is maintained; Wherein, the first threshold is greater than the second threshold, and the second adjustment range is less than the first adjustment range.

10. The method for moisture-proofing the transformer body according to claim 1, characterized in that... In step three, when dry nitrogen gas at 80°C to 100°C is introduced into the vacuum tank, the gas is introduced simultaneously through at least two air inlets located at the bottom, middle and top of the vacuum tank, and exited from the other side symmetrical to the air inlets.

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