Oil-immersed transformer heat recovery process based on magnetic suspension heat pump system

Abstract

The application provides an oil-immersed transformer heat recovery process based on a magnetic suspension heat pump system, which comprises an insulating oil circulation loop, an oil-free magnetic suspension heat pump system, a modular heat energy recycling loop and a double-PLC control system; the oil-free magnetic suspension heat pump system comprises an oil-free magnetic suspension compressor, a multiple metal isolation and leakage detectable heat exchanger, an electronic expansion valve, a pipeline and a drying structure; heat recovery is realized through the following steps, direct emission of a large amount of waste heat to the atmosphere is avoided, the local exacerbation problem of urban "heat island effect" is relieved, the operation noise of the oil-free magnetic suspension compressor is far lower than that of a traditional large fan, on one hand, indirect power generation carbon emission is reduced through power saving, on the other hand, fossil fuel boiler is replaced by heat production, combustion carbon emission is directly reduced, meanwhile, the service life of the transformer is prolonged, and the hidden carbon emission in the equipment manufacturing and replacement process is reduced.

Description

Technical Field

[0001] This application relates to the cross-technical field of energy conservation and heat recovery in power equipment, specifically to a heat recovery process for an oil-immersed transformer based on a magnetic levitation heat pump system. Background Technology

[0002] Oil-immersed power transformers are core equipment for power grids and enterprise power transmission. Their total operating losses (iron losses + copper losses) are enormous. A single 220KV / 300MVA oil-immersed transformer with a rated loss of 675KW can lose up to 5.4 million kWh per year after 8000 hours of operation. The total annual loss of transformers in the national industrial sector exceeds 10 billion kWh. Existing technology has two major pain points: Energy efficiency bottlenecks and cooling limitations: Traditional oil-immersed transformers rely on natural oil circulation and air cooling or forced oil circulation and air cooling. The cooling effect is significantly affected by the ambient temperature. When the ambient temperature is ≥30℃ or the transformer load rate is >80%, the insulating oil temperature can easily rise to 65-95℃, causing the coil resistance to increase linearly with temperature (the resistance increases by 0.4% for every 1℃ increase in copper coil temperature), and the load loss increases by an additional 5%-15%. Moreover, high temperature will accelerate the aging of insulating oil and shorten the transformer life. Insufficient safety and efficiency of heat recovery: Currently, there are virtually no heat recovery solutions. A few use ordinary water-cooled heat exchangers, which pose two major risks: First, the pipelines are prone to micro-cracks (≤0.1mm) due to corrosion and fatigue, or welding defects at the tube expansion and sealing points, leading to cross-contamination between the insulating oil and the heat exchange medium, causing equipment short circuits or catastrophic system failures such as transformer damage. Second, ordinary water-cooled heat exchangers use water to cool the oil, and waste heat recovery can only obtain low-grade heat energy (≤50℃), which is insufficient to meet the heating needs of production and daily life (usually requiring 55-70℃). The industry urgently needs a technical solution that combines "high-efficiency cooling and energy saving, high-grade heat recovery, and safe isolation." The frictionless and high-efficiency characteristics of the oil-free magnetic levitation compressor, along with the safety isolation advantages of the self-developed multi-metal isolation and leak-detectable heat exchanger, provide technical support for solving the above pain points. Summary of the Invention

[0003] This application provides a heat recovery process for an oil-immersed transformer based on a magnetic levitation heat pump system to address one of the aforementioned technical deficiencies.

[0004] To achieve the above objectives, this application provides the following technical solution: a heat recovery process for an oil-immersed transformer based on a magnetic levitation heat pump system, comprising: an insulating oil circulation loop, an oil-free magnetic levitation heat pump system, a modular heat energy recovery loop, and a dual PLC control system. The oil-free magnetic levitation heat pump system includes an oil-free magnetic levitation compressor, a multi-metal isolated and leak-detectable heat exchanger (evaporator / condenser), an electronic expansion valve, piping, and a drying structure. Heat recovery is achieved through the following steps: Step 1: The insulating oil enters the evaporator through the circulating pump and pipeline. After the insulating oil working fluid is cooled by heat exchange, it returns to the transformer through the pipeline to reduce the coil resistance and loss. Step 2: The steam inside the evaporator enters the oil-free magnetic levitation compressor after passing through the drying structure and pipes. The oil-free magnetic levitation compressor compresses the working fluid into a high-temperature gas, which then enters the condenser through pipes to exchange heat with the recycled cold water, outputting hot water at 55-70℃. Step 3: The PLC control system monitors parameters through sensors, triggers an alarm and shuts off the valve when a leak occurs.

[0005] In any of the above technical solutions, the oil-free magnetic levitation compressor is further provided with radial and axial magnetic levitation bearings, which are free of lubricating oil, have a COP≥10, and are compatible with R134A working fluid.

[0006] In any of the above technical solutions, the drying structure further includes a sleeve connected to the outside of the pipe, a placement cavity is formed in the inner wall of the sleeve, a water absorption structure is provided inside the placement cavity, a hollow diversion column is fixedly installed on the side of the inner wall of the sleeve, an inclined hole is formed in the circumferential direction on the top of the outer surface of the hollow diversion column, a one-way valve is fixedly installed inside the inclined hole of the hollow diversion column, a diversion hole is formed at the bottom of the outer surface of the hollow diversion column, circular plates are equidistantly installed inside the hollow diversion column, and a gas reversing structure is installed on the circular plate located at the bottom of the inner wall of the hollow diversion column.

[0007] In any of the above technical solutions, the outer surface of the circular plate is provided with vent holes in the circumferential direction, and the center points of the vent holes of the two circular plates coincide. The outer side of the circular plate and the inner wall of the hollow drainage column are fitted together and a sealing gasket is provided.

[0008] In any of the above technical solutions, the gas reversing structure further includes a driving component fixedly installed on the top of the circular plate. The output end of the driving component passes through the circular plate and is fixedly installed with an octagonal plate. An arc-shaped plate is fixedly installed on the outside of the octagonal plate. Rubber rings are installed inside both the arc-shaped plate and the octagonal plate.

[0009] In any of the above technical solutions, the maximum width of the arc-shaped plate is greater than the maximum diameter of the diversion hole, and the octagonal plate is configured with eight sides and corners, the width of the eight sides and corners being greater than the maximum diameter of the air outlet.

[0010] In any of the above technical solutions, a water flow hole is further provided inside the sleeve at the bottom of the inner wall of the placement cavity. A plug head is vertically slidably connected inside the water flow hole of the sleeve. An abutment plate is fixedly installed at the bottom of the plug head. A threaded disc is rotatably connected to the bottom of the abutment plate, and the threaded disc and the sleeve are threadedly connected. A positioning post is connected through the abutment plate. The positioning post is fixedly installed at the bottom of the inner wall of the sleeve. A groove is provided inside the sleeve corresponding to the bottom of the abutment plate.

[0011] In any of the above technical solutions, a flow guiding chamber is further provided on the side of the sleeve near the groove, and the end face of the flow guiding chamber near the axis of the sleeve is inclined, and the top edge of the abutment plate away from the axis of the sleeve is inclined.

[0012] In any of the above technical solutions, a pressure ring is further slidably connected vertically at the top of the placement cavity inside the sleeve, and a plurality of columns penetrating the sleeve are fixedly installed at the top of the pressure ring, and a push ring is fixedly installed between the tops of the plurality of columns.

[0013] In any of the above technical solutions, the inclined hole is further defined as having a larger end near the sleeve than the other end, and the pressure ring is located above and fitted to the water-absorbing structure.

[0014] Compared with the prior art, the method provided in this application has the following technical advantages: By recycling and utilizing the waste heat from transformers, the large amount of waste heat that traditional cooling towers or air-cooled heat dissipation directly emit into the atmosphere is avoided, which alleviates the problem of localized aggravation of the urban "heat island effect". At the same time, the operating noise of the oil-free magnetic levitation compressor is much lower than that of traditional large fans. On the one hand, it reduces carbon emissions from indirect power generation by saving electricity, and on the other hand, it directly reduces carbon emissions from combustion by replacing fossil fuel boilers with heat generation. In addition, extending the life of transformers also reduces the hidden carbon emissions during equipment manufacturing and replacement. The oil-free magnetic levitation compressor is small in size and light in weight. The entire heat recovery system has a compact structure, making it particularly suitable for scenarios with limited space in substations, renovation of old machine rooms, or intensive design, without the need for a large additional cooling tower. Simplified peripheral systems: The system operates in a closed loop, eliminating the need for complex peripheral facilities such as water treatment, corrosion prevention, and freeze protection that may be required in traditional water cooling systems, thus reducing system complexity and potential failure points.

[0015] It should be understood that both the foregoing general description and the following detailed description are for illustrative purposes and do not necessarily limit the scope of this disclosure. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate the subject matter of this disclosure. Furthermore, the specification and drawings serve to explain the principles of this disclosure. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the specific embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation of this application.

[0017] Figure 1 This is a flowchart of an embodiment of the present disclosure; Figure 2 This is a schematic diagram of the structure of an embodiment of the present disclosure; Figure 3 This is an exploded view of an embodiment of this disclosure; Figure 4 This is a cross-sectional view of the drying structure in an embodiment of this disclosure; Figure 5 This is a schematic diagram of the installation structure of the arc-shaped plate in an embodiment of this disclosure; Figure 6 This is a schematic diagram of the installation structure of the plug head in an embodiment of this disclosure; Figure 7 This is a schematic diagram of the installation structure of the column according to an embodiment of this disclosure; Icons: 1. Condenser; 2. Pipe; 3. Electronic expansion valve; 4. Evaporator; 5. Drying structure; 51. Sleeve; 52. Placement chamber; 53. Water suction structure; 54. Guide chamber; 56. Groove; 57. Hollow guide column; 58. Inclined hole; 59. One-way valve; 510. Circular plate; 513. Diverter hole; 514. Drive component; 515. Octagonal plate; 516. Arc plate; 517. Rubber ring; 518. Abutment plate; 519. Plug head; 520. Threaded disc; 521. Positioning column; 522. Pressure ring; 523. Column; 524. Push ring; 525. Drain hole; 526. Drain pipe; 6. Oil-free magnetic levitation compressor. Detailed Implementation

[0018] This invention discloses an oil-immersed transformer heat recovery process based on a magnetic levitation heat pump system to solve the existing problems of energy efficiency bottlenecks, cooling limitations, and low safety and efficiency in heat recovery.

[0019] To make the technical solutions and advantages of the embodiments of this application clearer, the exemplary embodiments of this application will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not an exhaustive list of all embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0020] Please see Figures 1-7 A heat recovery process for an oil-immersed transformer based on a magnetic levitation heat pump system includes: an insulating oil circulation loop, an oil-free magnetic levitation heat pump system, a modular heat energy recovery loop, and a dual PLC control system. The oil-free magnetic levitation heat pump system includes an oil-free magnetic levitation compressor 6, a multi-metal isolation and leak-detectable heat exchanger (evaporator 4 / condenser 1), an electronic expansion valve 3, piping 2, and a drying structure 5. Heat recovery is achieved through the following steps: Step 1: The insulating oil enters the evaporator 4 through the circulating pump and pipeline 2. After the insulating oil working fluid is cooled by heat exchange, it returns to the transformer through pipeline 2, thereby directly reducing the coil operating temperature and resistance, reducing the additional copper loss (5%-15%) caused by high temperature, and realizing the transformer's active energy saving. This process not only reduces energy consumption, but also fundamentally inhibits the thermal aging rate of the insulating oil by stabilizing the oil temperature within the optimal range (35-45℃), thereby extending the insulation life of the transformer by more than 100%, significantly improving the return on assets and power supply reliability. The heat exchanger (evaporator 4 / condenser 1) with multiple metal isolation and leak detection has both hot and cold media, and is physically isolated by multiple metals to ensure that the hot and cold media never cross-contaminate, improving the safety of the heat exchanger, ensuring the safety of the transformer oil, and isolating the heated user circulating water and Freon from each other. Step 2: The steam inside the evaporator 4 enters the oil-free magnetic levitation compressor 6 after passing through the drying structure 5 and the pipe 2. The oil-free magnetic levitation compressor 6 compresses the working fluid into a high-temperature gas, which then enters the condenser 1 through the pipe 2 to exchange heat with the recycled cold water, outputting hot water at 55-70℃. This process solution fundamentally breaks through the above limitations through active cooling by the magnetic levitation heat pump and intrinsically safe heat exchange. The high-quality hot water output can be directly and seamlessly connected to the heating system, process heating or domestic hot water demand, replacing the traditional gas boiler or electric heating device. While recovering waste heat, it realizes the supply-side substitution of energy, and its comprehensive energy utilization rate can be increased to more than 150%. Step 3: The PLC control system monitors parameters through sensors. When a leak occurs, it triggers an alarm and shuts off the valve. This intelligent control system integrates an adaptive optimization algorithm, which can dynamically adjust the heat pump operating frequency and the opening degree of the electronic expansion valve 3 according to changes in transformer load, ambient temperature, and heat demand. This ensures that the system always operates at the optimal energy efficiency point and uploads all operating data to the cloud to achieve remote monitoring and energy efficiency big data analysis. This provides decision support for predictive maintenance and energy management. The dual PLC control systems can be switched, and each can control the operation of the device independently.

[0021] In existing technologies, traditional oil-immersed transformers rely on natural oil circulation and air cooling or forced oil circulation and air cooling. The cooling effect is significantly affected by the ambient temperature. When the ambient temperature is ≥30℃ or the transformer load rate is >80%, the insulating oil temperature can easily rise to 65-95℃, causing the coil resistance to increase linearly with temperature (the resistance increases by 0.4% for every 1℃ increase in copper coil temperature), and the load loss increases by an additional 5%-15%. Moreover, high temperature will accelerate the aging of insulating oil and shorten the transformer's lifespan. At the same time, some transformers use ordinary water-cooled heat exchangers, which pose two major risks: First, the pipeline is prone to micro-cracks (≤0.1mm) due to corrosion and fatigue, or welding defects at the expansion tube sealing position, which can lead to cross-contamination between the insulating oil and the heat exchange medium, causing equipment short circuits or catastrophic system failures such as transformer damage. Second, ordinary water-cooled heat exchangers use water to cool the oil, and the waste heat recovery can only obtain low-grade heat energy (≤50℃), which is difficult to meet the heating needs of production and daily life (usually 55-70℃). This process uses heat pump circulation to upgrade the waste heat grade to a high-value range, realizing the cascade utilization of energy.

[0022] By recovering and utilizing waste heat from transformers, this system avoids the direct emission of large amounts of waste heat into the atmosphere, unlike traditional cooling towers or air-cooled systems. This alleviates the localized exacerbation of the urban heat island effect. Simultaneously, the oil-free magnetic levitation compressor operates at significantly lower noise levels than traditional large fans. This reduces carbon emissions from indirect power generation through energy conservation and directly reduces combustion carbon emissions by replacing fossil fuel boilers with heat generation. Furthermore, extending transformer lifespan reduces hidden carbon emissions during equipment manufacturing and replacement. Through this triple carbon reduction pathway of "energy saving + heat generation + life extension," calculations show that a typical medium-sized substation can reduce carbon dioxide emissions by hundreds of tons annually, demonstrating significant environmental benefits. This system represents a key micro-unit technology for building a green power grid and achieving dual-carbon goals. The oil-free magnetic levitation compressor is small in size and light in weight. The entire heat recovery system has a compact structure, making it particularly suitable for scenarios with limited space in substations, renovation of old machine rooms, or intensive design. It does not require the addition of a large cooling tower. Its modular design makes the system installation and deployment quick and flexible, which can greatly shorten the project cycle and significantly reduce the transformer power outage time caused by renovation and construction. It is of great value for ensuring continuous power supply. Simplified peripheral systems: The closed-loop operation of the system eliminates the need for complex peripheral facilities such as water treatment, corrosion prevention, and antifreeze that may be required in traditional water cooling systems. This reduces system complexity and potential failure points, which not only reduces initial investment but also fundamentally eliminates the risk of system downtime caused by cooling water quality deterioration, pipe scaling, or winter freezing. This improves the long-term operational stability and maintenance-free nature of the system in complex environments and unattended scenarios.

[0023] During use, the high-temperature insulating oil (65-95℃) inside the transformer is transported to the heat exchanger (evaporator 4) by the circulating pump to exchange heat with the low-temperature heat pump working fluid (10-20℃). After the oil temperature drops to 35-45℃, it flows back to the transformer, and the coil temperature decreases simultaneously, the resistance decreases, and the load loss decreases. After absorbing heat, the heat pump working fluid evaporates into gas and enters the oil-free magnetic levitation compressor 6 through the pipe 2 and the drying structure 5.

[0024] The oil-free magnetic levitation compressor 6 compresses the low-temperature working gas into a high-temperature and high-pressure gas (70-80℃), which is then transported to the heat recovery chilled water (30-45℃) in the heat exchanger (condenser 1) for heat exchange. After the working gas condenses into a liquid, it returns to the evaporator 4 through the electronic expansion valve 3 via the pipeline 2. The heat recovery chilled water absorbs heat and is heated to 55-70℃.

[0025] High-temperature hot water or high-temperature air is delivered to the heat-using terminal (such as boiler feedwater preheating or high-temperature air preheating of materials) through pipe 2. The control system monitors various parameters in real time. If a heat exchanger leak is detected (such as heat pump working fluid seeping into the leak channel), the working fluid low-pressure sensor will immediately trigger an alarm, and the recovery system will stop for inspection to prevent media cross-contamination.

[0026] Specifically, two connection ports are provided on the same side of the outer surface of condenser 1, one for connecting to municipal cold water and the other as a return port. Two guide holes are provided on the other side of the outer surface of condenser 1. One end of the guide hole at the bottom of condenser 1 is connected to pipe 2, and the other end of pipe 2 is connected to electronic expansion valve 3. The other end of electronic expansion valve 3 is connected to evaporator 4 through pipe 2. Two guide ports are provided on one end face of evaporator 4. One end of electronic expansion valve 3 is connected to the guide port at the bottom of evaporator 4 through pipe 2. The guide hole at the top of one end of evaporator 4 is connected to drying structure 5 through pipe 2. The outlet of drying structure 5 is connected to oil-free magnetic levitation compressor 6 through pipe 2. The air inlet of compressor 6 is connected to pipe 2 of drying structure 5. The air outlet of oil-free magnetic levitation compressor 6 is connected to the guide port at the top of condenser 1 through pipe 2. Two flow holes are provided at the other end of evaporator 4. One flow hole is connected to the oil outlet of heat exchanger through pipe 2, and the other flow hole is connected to the circulation pump through pipe 2. The outlet of circulation pump is connected to the oil return port of heat exchanger through pipe 2. Oil-free magnetic levitation compressor 6 adopts radial + axial magnetic levitation bearings, has no lubricating oil, COP (coefficient of performance) ≥6, has extremely high electrical energy to heat energy conversion efficiency, and is compatible with R134A (medium and low temperature environmentally friendly refrigerant (working fluid) with zero ozone depletion potential) working fluid.

[0027] In one specific embodiment, the drying structure 5 includes a sleeve 51 connected to the outside of the pipe 2. The inner wall of the sleeve 51 has a placement cavity 52, and the placement cavity 52 is provided with a water absorption structure 53. A hollow diversion column 57 is fixedly installed on the side of the inner wall of the sleeve 51. An inclined hole 58 is circumferentially opened on the top of the outer surface of the hollow diversion column 57. A one-way valve 59 is fixedly installed inside the inclined hole 58 of the hollow diversion column 57. A diversion hole 513 is opened on the bottom of the outer surface of the hollow diversion column 57. Circular plates 510 are equidistantly installed inside the hollow diversion column 57. A gas reversing structure is installed on the circular plate 510 located at the bottom of the inner wall of the hollow diversion column 57.

[0028] When in use, the gas switching structure is activated to switch to dehumidification mode. At this time, the gas cannot flow directly along the circular plate 510. The gas containing moisture is guided to the diversion hole 513 and enters the placement chamber 52. When it flows through the water absorption structure 53 (such as water-absorbing cotton) in the placement chamber 52, the moisture in the gas is efficiently absorbed, thereby accurately removing the moisture and acidic components that may damage the compressor. The dried gas then enters the hollow diversion column 57 again through the one-way valve 59 of the inclined hole 58, and enters the oil-free magnetic levitation compressor 6 along the pipe 2. This process can actively protect the magnetic bearing and motor from moisture corrosion and fundamentally prevent system failures caused by insulation degradation or ice blockage. When the working fluid is sufficiently dried or the system requires high-efficiency operation, the gas reversing structure is activated, switching to a direct-flow mode. This structure blocks the diversion orifice 513, and the gas-liquid mixture flows directly along the channel formed by the circular plate 510 inside the hollow guide column 57. At the same time, the one-way valve 59 in the inclined orifice 58 closes under the action of pressure difference to prevent gas from entering the placement chamber 52. This design significantly reduces the permanent pressure loss flowing through the dryer, minimizes the system flow resistance, directly improves the overall energy efficiency (COP) of the heat pump cycle, and helps extend the service life of the absorbent material.

[0029] One end of pipe 2 is connected to a sleeve 51 via a thread. The inner wall of sleeve 51 has a placement cavity 52. ​​The placement cavity 52 is equipped with a water-absorbing structure 53 (the water-absorbing structure 53 is specifically a water-absorbing cotton). A hollow drainage column 57 is fixedly installed on the inner wall of sleeve 51. The top of the outer surface of the hollow drainage column 57 has inclined holes 58 equidistantly circumferentially opened. A one-way valve 59 is snapped into the inclined holes 58 of the hollow drainage column 57. The bottom of the outer surface of the hollow drainage column 57 has diversion holes 513 equidistantly circumferentially opened. Circular plates 510 are equidistantly installed inside the hollow drainage column 57. A gas diversion structure is installed on the circular plate 510 located at the bottom of the inner wall of the hollow drainage column 57. The outer surface of the circular plate 510 has circumferentially equidistantly opened air outlets, and the center points of the air outlets of the two circular plates 510 coincide. The outer side of the circular plate 510 and the inner wall of the hollow drainage column 57 are in contact and a sealing gasket is provided.

[0030] In one specific embodiment, the gas switching structure includes a drive member 514 fixedly installed on the top of the circular plate 510. The output end of the drive member 514 passes through the circular plate 510 and is fixedly installed with an octagonal plate 515. An arc-shaped plate 516 is fixedly installed on the outside of the octagonal plate 515. Rubber rings 517 are installed inside both the arc-shaped plate 516 and the octagonal plate 515 to ensure high sealing performance during operation.

[0031] When the system determines that dehumidification is needed, the drive unit 514 starts, driving the octagonal plate 515 and the arc plate 516 to rotate synchronously. In the first stage, the octagonal plate 515 rotates precisely until it completely blocks the central air outlet on the circular plate 510. At the same time, the arc plate 516 is misaligned with the diversion hole 513. This forces all working fluids to change their flow direction and enter the dehumidification bypass. Subsequently, the drive unit 514 continues to run and enters the second stage: the octagonal plate 515 separates from the central air outlet and reopens the main flow channel; at the same time, the arc plate 516 rotates to precisely coincide with the diversion hole 513, and the deformation of the rubber ring 517 achieves a seal, thereby reliably closing the diversion bypass. At this time, the system switches to the direct flow mode. Through precise angle control of a single drive component 514, the linkage and interlocking opening and closing of two key flow channels (main flow channel and dehumidification bypass) are achieved. This not only ensures absolute reliability and efficiency of mode switching and avoids crosstalk in the internal flow path, but its tight sealing design also fundamentally prevents working fluid leakage, ensuring stable system pressure and long-term operational reliability. This provides the mechanical basis for the drying structure to achieve the intelligent function of "on-demand dehumidification". The ingenious mechanical linkage design requires only a single power input to complete the complex flow path reconstruction, greatly improving the reliability of the actuator and reducing the complexity of electrical control. Its fully mechanical interlocking principle also eliminates the risk of two modes being opened simultaneously due to software errors.

[0032] Specifically, a drive component 514 is installed above the top of the circular plate 510 located at the bottom of the inner wall of the hollow diversion column 57. The drive component 514 is a drive motor. The output end of the drive component 514 passes through the circular plate 510 and is fixedly installed with an octagonal plate 515 by a key. An arc plate 516 is fixedly installed on the outside of the octagonal plate 515. Rubber rings 517 are installed inside both the arc plate 516 and the octagonal plate 515 to ensure high sealing during operation. The maximum width of the arc plate 516 is greater than the maximum diameter of the diversion hole 513. The octagonal plate 515 is set with eight corners, and the width of the eight corners is greater than the maximum diameter of the air outlet.

[0033] In one specific embodiment, a water outlet 525 is provided inside the sleeve 51 at the bottom of the inner wall of the placement cavity 52. ​​A plug head 519 is vertically slidably connected inside the water outlet 525 of the sleeve 51. An abutment plate 518 is fixedly installed at the bottom of the plug head 519. A threaded disc 520 is rotatably connected to the bottom of the abutment plate 518, and the threaded disc 520 and the sleeve 51 are threadedly connected. A positioning post 521 is connected through the abutment plate 518 and is fixedly installed at the bottom of the inner wall of the sleeve 51. A groove 56 is provided inside the sleeve 51 corresponding to the bottom of the abutment plate 518.

[0034] In use, rotating the threaded disc 520 causes the abutment plate 518 to move along the outside of the positioning post 521 into the groove 56. Simultaneously, the abutment plate 518 causes the plug head 519 to flow along the inside of the drainage hole 525, exposing the drainage hole 525. At this point, the liquid inside the placement cavity 52 flows along the drainage hole 525 onto the abutment plate 518, and then along the abutment plate 518 into the guide chamber 54. Finally, it is discharged along the drain pipe 526, thus achieving liquid discharge and changing the liquid discharge method. The design overcomes the difficulty of controlling the discharge of absorbed liquid from the absorbent structure 53 (absorbent cotton), creating conditions for subsequent compression and regeneration operations and improving the maintainability of the structure. This drainage mechanism is precisely designed and can be finely adjusted through the threaded disc 520. It can ensure absolute sealing when closed to prevent leakage of the working fluid, and can also achieve smooth flow when opened. The collected liquid can be centrally analyzed, and its composition and quantity can serve as an important diagnostic basis for judging the dryness and potential contamination status of the system. This realizes the extension of functions from maintenance operation to condition monitoring.

[0035] A drainage hole 525 is circumferentially opened inside the sleeve 51 at the bottom of the inner wall of the placement cavity 52. ​​A plug head 519 is vertically slidably connected inside the drainage hole 525 of the sleeve 51. A sealing ring is provided on the outside of the plug head 519. An abutment plate 518 is fixedly installed at the bottom of the plug head 519. A threaded disc 520 is rotatably connected to the bottom of the abutment plate 518, and the threaded disc 520 and the sleeve 51 are threadedly connected. A positioning post 521 is connected through the abutment plate 518. The positioning post 521 is fixedly installed at the bottom of the inner wall of the sleeve 51. A groove 56 is opened inside the sleeve 51 corresponding to the bottom of the abutment plate 518. A flow guiding chamber 54 is opened on the side of the sleeve 51 near the groove 56. The end face of the flow guiding chamber 54 near the axis of the sleeve 51 is inclined. An inclined surface is opened on the top edge of the abutment plate 518 away from the axis of the sleeve 51. A drain pipe 526 is embedded in the bottom edge of the sleeve 51.

[0036] In one specific embodiment, a pressure ring 522 is vertically slidably connected inside the sleeve 51 at the top of the placement cavity 52. ​​Several columns 523 penetrating the sleeve 51 are fixedly installed at the top of the pressure ring 522. A push ring 524 is fixedly installed between the tops of the columns 523. The inclined hole 58 is larger at one end near the sleeve 51 than at the other end. The pressure ring 522 is located above the water absorption structure 53 and fits against it.

[0037] In use, the push ring 524 is pushed, which drives the pressure ring 522 downward through the column 523. As the pressure ring 522 moves downward, it presses the water-absorbing structure 53, causing the water-absorbing structure 53 to be compressed. After the water-absorbing structure 53 is compressed, the liquid flows out along the inside of the water outlet 525. This extrusion regeneration function can force the water out of the saturated water-absorbing material, significantly restoring its moisture absorption capacity. It transforms the "disposable consumable" into a "maintainable component", greatly extending its service life and reducing the maintenance cost and material waste throughout the entire cycle. Compared with the traditional heating regeneration, this mechanical extrusion regeneration method has the advantages of low energy consumption, safe operation (no high temperature), and no damage to the crystal structure of the water-absorbing material. By performing this operation regularly, it can be ensured that the moisture absorption performance of the drying structure is maintained at a high efficiency of over 80% for a long time. This ensures that the entire heat pump system can still guarantee the intake air dryness of the core compressor even in humid areas or after long-term operation. This is crucial for maintaining system energy efficiency (COP≥10) and eliminating the risk of ice blockage.

[0038] Specifically, a pressure ring 522 is vertically slidably connected inside the sleeve 51 at the top of the placement cavity 52. ​​Three columns 523 penetrating the sleeve 51 are fixedly installed at the top of the pressure ring 522. The same push ring 524 is fixedly installed between the tops of the three columns 523. The inclined hole 58 is larger at one end near the sleeve 51 than at the other end. The pressure ring 522 is located above the water absorption structure 53 and fits against it.

[0039] Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this disclosure.

[0040] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0042] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0043] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0044] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A heat recovery process for an oil-immersed transformer based on a magnetic levitation heat pump system, characterized in that, include: Insulating oil circulation loop, oil-free magnetic levitation heat pump system, modular heat energy recovery loop and dual PLC control system; The oil-free magnetic levitation heat pump system includes an oil-free magnetic levitation compressor (6), a multi-metal isolation and leak-detectable heat exchanger (evaporator (4) / condenser (1)), an electronic expansion valve (3), pipes (2), and a drying structure (5), and achieves heat recovery through the following steps: Step 1: The insulating oil enters the evaporator (4) through the circulating pump and pipeline (2). After the insulating oil working fluid is cooled by heat exchange, it returns to the transformer through pipeline (2) to reduce the coil resistance and loss. Step 2: The steam inside the evaporator (4) enters the oil-free magnetic levitation compressor (6) after passing through the drying structure (5) and the pipe (2). The oil-free magnetic levitation compressor (6) compresses the working fluid into a high-temperature gas and enters the condenser (1) through the pipe (2) to exchange heat with the recycled cold water, outputting hot water at 55-70℃. Step 3: The PLC control system monitors parameters through sensors, triggers an alarm and shuts off the valve when a leak occurs.

2. As described in claim 1, characterized in that, The oil-free magnetic levitation compressor (6) is equipped with radial and axial magnetic levitation bearings, has no lubricating oil, COP≥10, and is compatible with R134A working fluid.

3. The heat recovery process for an oil-immersed transformer based on a magnetic levitation heat pump system according to claim 2, characterized in that, The drying structure (5) includes a sleeve (51) connected to the outside of the pipe (2). The inner wall of the sleeve (51) is provided with a placement cavity (52). The placement cavity (52) is provided with a water absorption structure (53). A hollow diversion column (57) is fixedly installed on the side of the inner wall of the sleeve (51). An inclined hole (58) is provided on the top circumferential surface of the hollow diversion column (57). A one-way valve (59) is fixedly installed inside the inclined hole (58) of the hollow diversion column (57). A diversion hole (513) is provided on the bottom of the outer surface of the hollow diversion column (57). Circular plates (510) are installed at equal intervals inside the hollow diversion column (57). A gas reversing structure is installed on the circular plate (510) located at the bottom of the inner wall of the hollow diversion column (57).

4. The heat recovery process for an oil-immersed transformer based on a magnetic levitation heat pump system according to claim 3, characterized in that, The outer surface of the circular plate (510) is provided with vent holes in the circumference, and the center points of the vent holes of the two circular plates (510) coincide. The outer side of the circular plate (510) and the inner wall of the hollow drainage column (57) are fitted together and a sealing gasket is provided.

5. The heat recovery process for an oil-immersed transformer based on a magnetic levitation heat pump system according to claim 4, characterized in that, The gas switching structure includes a drive unit (514) fixedly installed on the top of the circular plate (510). The output end of the drive unit (514) passes through the circular plate (510) and is fixedly installed with an octagonal plate (515). An arc plate (516) is fixedly installed on the outside of the octagonal plate (515). Rubber rings (517) are installed inside both the arc plate (516) and the octagonal plate (515).

6. The heat recovery process for an oil-immersed transformer based on a magnetic levitation heat pump system according to claim 5, characterized in that, The maximum width of the arc plate (516) is greater than the maximum diameter of the diversion hole (513), and the octagonal plate (515) is configured with eight sides and corners, the width of the eight sides and corners being greater than the maximum diameter of the air outlet.

7. The heat recovery process for an oil-immersed transformer based on a magnetic levitation heat pump system according to claim 6, characterized in that, A water outlet (525) is provided inside the sleeve (51) at the bottom of the inner wall of the placement cavity (52). A plug head (519) is vertically slidably connected inside the water outlet (525) of the sleeve (51). An abutment plate (518) is fixedly installed at the bottom of the plug head (519). A threaded disc (520) is rotatably connected at the bottom of the abutment plate (518). The threaded disc (520) and the sleeve (51) are threadedly connected. A positioning post (521) is connected through the abutment plate (518). The positioning post (521) is fixedly installed at the bottom of the inner wall of the sleeve (51). A groove (56) is provided inside the sleeve (51) corresponding to the bottom of the abutment plate (518).

8. The heat recovery process for an oil-immersed transformer based on a magnetic levitation heat pump system according to claim 7, characterized in that, The sleeve (51) has a flow guiding chamber (54) on the side near the groove (56) inside. The end face of the flow guiding chamber (54) near the axis of the sleeve (51) is inclined. The abutment plate (518) has an inclined surface at the top edge away from the axis of the sleeve (51).

9. The heat recovery process for an oil-immersed transformer based on a magnetic levitation heat pump system according to claim 8, characterized in that, Inside the sleeve (51), a pressure ring (522) is vertically slidably connected to the top of the placement cavity (52). Several columns (523) penetrating the sleeve (51) are fixedly installed at the top of the pressure ring (522), and a push ring (524) is fixedly installed between the tops of the columns (523).

10. The heat recovery process for an oil-immersed transformer based on a magnetic levitation heat pump system according to claim 9, characterized in that, The inclined hole (58) is larger at one end near the sleeve (51) than at the other end, and the pressure ring (522) is located above and in contact with the water-absorbing structure (53).

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