An immersion evaporative cooling system suitable for vertical motor rotors

Abstract

The present invention relates to an immersion evaporative cooling system suitable for a vertical motor rotor, comprising a condenser, a magnetic pole coil, a sealing liquid box and a connecting pipe. The magnetic pole coil is placed inside the sealing liquid box, and the inside of the sealing liquid box is perfused with a liquid evaporative cooling medium, so that the magnetic pole coil is completely immersed in the liquid medium, that is, the liquid level of the liquid medium is higher than the magnetic pole coil; the top of the sealing liquid box is connected to the condenser through a connecting pipe, and the gaseous evaporative cooling medium generated inside the sealing liquid box flows to the condenser through the connecting pipe, and the liquid medium generated after condensation by the condenser also flows back to the sealing liquid box through the connecting pipe, so that only the connecting pipe needs to be set between the top of the sealing liquid box and the condenser to realize the two-way flow of liquid medium and gaseous medium at the same time, without the need to set a separate liquid return pipe between the bottom of the sealing liquid box and the condenser.

Description

Technical Field

[0001] The invention relates to an immersion evaporative cooling system suitable for a vertical motor rotor. Background Art

[0002] Looking at the cooling technology of hydro-turbine generators, it has roughly experienced a development process from air cooling to water cooling, and then to air cooling. Since the 1930s, hydro-turbine generators have been using air cooling, that is, using air to cool the stator and rotor windings and the surface of the core (that is, the "full air cooling solution"). In order to meet the requirements of improving generator efficiency and reducing operating costs, the single-unit capacity of the generator must be further improved. The application of water cooling technology in hydro-turbine generators can effectively reduce the temperature difference of the winding rods, make the temperature distribution of the generator windings uniform, and extend the insulation life. The temperature rise of the stator core is also greatly reduced compared to the air cooling method. However, with the continuous deepening and expansion of the application research of water cooling technology in hydro-turbine generators, some unfavorable factors have gradually emerged. Water-cooled motors require the installation of a water purification system in the hydropower station, which increases the complexity of system operation and reduces reliability. Due to the formation of scale and the oxidation of hollow copper wires by oxygen ions in the water to produce copper oxide and cuprous oxide, it is easy to cause water blockage. Water joints and various sealing points leak due to water pressure, and the turns or rough points of the hollow conductors cause winding leakage due to hydraulic drilling, and the motor faces the risk of burning insulation. At the same time, since the rotor is water-cooled, it will increase the complexity of the structure, bring a lot of inconvenience to processing, installation, operation and maintenance, and affect the reliability of the unit. Therefore, the rotor winding water-cooled solution is rarely used in large-capacity hydro-turbine generators.

[0003] On the premise of meeting the heat dissipation needs of the generator, the full air-cooling solution has the advantages of simple structure, reliable operation, and convenient maintenance compared with the full water-cooling solution (i.e., both the stator and rotor windings are water-cooled), which can effectively reduce the secondary operating costs of the power plant. With the continuous improvement of the insulation level of the generator, the wire rod fixing method and the ventilation system, great progress has been made in solving the cooling, heat resistance, deformation control, lamination process and other technologies of the air-cooled unit, which has improved the manufacturing limit of the air-cooled motor. Therefore, from the 1990s to the present, the cooling technology of conventional hydro-generators above 500MVA has gradually shifted to a pattern where the two strong solutions of full air cooling and semi-water cooling (stator winding water-cooled, stator core and rotor winding air-cooled) coexist, among which the full air-cooling solution has more prominent advantages in ultra-large capacity units. In addition, in order to solve the problem of water system failure of water-cooled motors and inherit the advantages of the internal cooling method, the Institute of Electrical Engineering of the Chinese Academy of Sciences has also carried out research on using evaporative cooling media instead of water internal cooling, called stator winding self-circulating evaporative cooling technology. It has been used in the Three Gorges underground power station, and the application of evaporative cooling technology on the rotor of hydro-turbine generators is still under study.

[0004] The paper "Self-circulating Evaporative Cooling Hydro-turbine Generator" (Liao Shaobao, Gu Guobiao, Li Zuozhi, "New Technology of Electrical Engineering and Power", Issue 3, 1987) details the internally cooled rotor evaporative cooling technology of the long pipe cooling circuit of the vertical motor. This technology uses a pole coil wound with a hollow conductor. The inlet and outlet of the hollow conductor are connected to the outlet and inlet of the condenser through pipes. The condenser is wrapped around the rotating shaft, and cooling water is provided to the condenser by water inlet from the shaft side. After experimental verification, the circulation state of this scheme is normal and the cooling effect is very good. The author also mentioned that the box structure is better for the rotor cooling circuit. However, the paper did not further describe the specific implementation plan of the box structure.

[0005] The invention patent "A rotor evaporative cooling device for a vertical motor" with the authorization announcement number CN 18494173A discloses a rotor evaporative cooling device for a vertical motor, which includes: a vertical motor rotor, a magnetic pole cooling chamber, a condenser and a connecting pipe, wherein the magnetic pole cooling chamber is a box-type structure wrapped around the outside of the rotor magnetic pole coil or a cavity structure composed of a magnetic pole coil and a magnetic pole support plate, and the space between the magnetic pole coil and the magnetic pole cooling chamber is filled with an evaporative cooling medium so that the magnetic pole coil is in a state of being immersed in the evaporative cooling medium. One end of the air outlet pipe is fixed to the air outlet of the magnetic pole cooling chamber, and the other end is fixed to the air inlet of the condenser. One end of the liquid return pipe is fixed to the liquid return port of the magnetic pole cooling chamber, and the other end is fixed to the liquid outlet of the condenser. Each of the three parts of the magnetic pole cooling chamber, the condenser and the connecting pipe has different implementation forms, and can form different combinations to adapt to a variety of application environments.

[0006] The rotor evaporative cooling scheme disclosed in the above invention patent has the following unavoidable defects: (1) The patent does not consider the rotor structure of the vertical motor. In its embodiment 1, the condenser is located above the rotor bracket, but in a conventional vertical motor, there is no extra space to place a bulky condenser. In its embodiments 2 to 4, the condenser is arranged at the shaft extension end on one side of the motor rotor, but in a conventional vertical motor, there is no spare shaft extension end for arranging the condenser, so it lacks engineering feasibility; (2) The patent does not consider the particularity of the application of the evaporative cooling system on the rotor. In the specific implementation method, the patent proposes that the condenser can be arranged inside the rotor bracket, but at the same time, the patent emphasizes that the condenser and the magnetic pole cooling cavity are connected by two pipes, one is the air outlet pipe and the other is the liquid return pipe. Then, when the condenser is arranged inside the rotor bracket and is not higher than the magnetic pole cooling cavity in the vertical direction, if the rotor does not rotate, according to the principle of the communicating vessel, the liquid evaporative cooling medium will be distributed in the magnetic pole cooling cavity and the condenser at the same time, and the liquid level inside the two in the vertical direction must be the same height. If the liquid evaporative cooling medium poured into the magnetic pole cooling cavity is too small to cover the upper part of the rotor magnetic pole during shutdown, the heat generated in the upper part of the rotor magnetic pole coil during shutdown cannot be cooled. If the liquid evaporative cooling medium poured into the magnetic pole cooling cavity is too large to cover the upper part of the rotor magnetic pole coil, then according to the communicating vessel principle, the condenser will also have the same height of liquid, which will not only lack evaporative cooling space and affect the cooling effect, but also waste the expensive evaporative cooling medium. (3) The claims and specific implementation schemes in the disclosed patent both mention that a rotary sealing technology is used between the condenser and the rotor to isolate the magnetic pole cooling cavity from the external space. However, there is currently no mature, stable, and long-term large-diameter, high-speed rotary sealing technology suitable for evaporative cooling medium and steam. Therefore, it cannot be realized in engineering. Summary of the invention

[0007] The invention solves the problem by providing an immersion evaporative cooling system suitable for a vertical motor rotor, which simplifies the design of the rotor evaporative cooling system, overcomes the shortcomings of the prior art solutions, and improves the reliability of the rotor evaporative cooling system.

[0008] The technical solution of the present invention is an immersion evaporative cooling system suitable for a vertical motor rotor, characterized in that it includes a condenser, a pole coil, a sealing liquid box and a connecting pipe, the pole coil is placed inside the sealing liquid box, the inside of the sealing liquid box is filled with liquid medium, so that the pole coil is completely immersed in the liquid medium, that is, the liquid level of the liquid medium is higher than the pole coil, the top of the sealing liquid box is connected to the condenser through the connecting pipe, the gaseous medium generated inside the sealing liquid box flows to the condenser through the connecting pipe, and the liquid medium generated after condensation in the condenser also flows back to the sealing liquid box through the connecting pipe, so that only a connecting pipe needs to be set between the top of the sealing liquid box and the condenser to simultaneously realize the two-way circulation of liquid medium and gaseous medium, and there is no need to set a separate return pipe between the bottom of the sealing liquid box and the condenser; when the rotor does not rotate, the pole coil is completely immersed in the liquid medium. When the rotor rotates, the magnetic pole coils heat up, the liquid medium absorbs heat and vaporizes, and the gaseous medium flows from the sealing liquid box to the condenser along the connecting pipe under the action of the pressure difference. The liquid medium generated after condensation in the condenser flows back to the sealing liquid box along the connecting pipe from the condenser under the action of the centrifugal force generated by the rotation of the rotor, thereby realizing self-circulation without the need for a circulating pump. In this way, only a connecting pipe needs to be set between the top of the sealing liquid box and the condenser, and the flow of the gaseous medium to the condenser and the flow of the liquid medium to the sealing liquid box can be realized at the same time, which simplifies the design of the rotor evaporative cooling system and greatly improves the reliability of the vertical motor.

[0009] The advantages of the present invention compared with the prior art are:

[0010] (1) In the previous non-rotating structure immersion evaporative cooling scheme, in order to obtain the flow pressure head, the height of the condenser is often higher than the sealing liquid box, an exhaust pipe is set between the top of the sealing liquid box and the condenser, and a return pipe is set between the condenser and the bottom of the sealing liquid box. When designing an immersion evaporative cooling scheme on a vertical motor rotor, there is no extra space for placing the condenser due to the relatively compact space above the rotor bracket. If the condenser is placed inside the rotor bracket with relatively abundant space, the condenser and the sealing liquid box are arranged at almost the same height. At this time, if the non-rotating structure immersion evaporative cooling scheme is still used and a return pipe is still set between the condenser and the bottom of the sealing liquid box, then when the rotor is stationary, according to the principle of communicating vessels, the liquid medium levels in the condenser and the sealing liquid box will be the same height. If the liquid level inside the sealing liquid box is too high, there will be a lack of evaporative cooling space, which will affect the cooling effect and waste the expensive evaporative cooling medium. If the liquid level inside the sealing liquid box is too low, the upper part of the magnetic pole coil placed inside the sealing liquid box will not be fully cooled. In the present invention, only the sealing liquid box has liquid medium inside, and when the rotor does not rotate, the magnetic pole coil is completely immersed in the liquid medium. The radial layout of the condenser and the sealing liquid box on the rotor must satisfy the radial position of the sealing liquid box is larger than the condenser. Then, when the rotor rotates, the gaseous medium with a lighter density flows from the sealing liquid box with a larger radius to the condenser with a smaller radius under the action of the pressure difference, and the liquid medium with a larger density produced after condensation flows from the condenser with a smaller radius to the sealing liquid box with a larger radius under the action of centrifugal force, thereby realizing self-circulation without the need for a circulating pump. By designing a suitable pipe diameter of the connecting pipe, it is only necessary to set a connecting pipe between the top of the sealing liquid box and the condenser to simultaneously realize the two-way circulation of the liquid medium and the gaseous medium, without the need to set a separate liquid return pipe between the bottom of the sealing liquid box and the condenser. The rotor evaporative cooling structure is optimized, and the reliability of the vertical motor is improved.

[0011] (2) In the solution proposed by the present invention, both gaseous and liquid media only flow on the rotor, so there is no need to involve a rotary seal with high technical difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the system structure of the present invention;

[0013] Figure 2 It is a typical structure of the sealing liquid box of the present invention;

[0014] Figure 3 for Figure 2 AA section view;

[0015] Figure 4 for Figure 2 DD profile diagram;

[0016] Figure 5 An embodiment of the present invention.

[0017] Among them, 1-rotating shaft, 2-rotor bracket, 3-pole body, 4-pole shoe, 5-pole coil, 6-condenser, 7-sealing liquid box, 8-connecting pipe, 27-lower cover plate, 28-outer box, 29-inner box, 30-upper cover plate, 31-pole support plate, 41-static water inlet pipe, 42-rotating water receiving tray, 43-static water throwing box. DETAILED DESCRIPTION

[0018] Before describing the present invention in detail, relevant terms are explained and illustrated.

[0019] Air cooling: Use air as a cooling medium to blow through the stator and rotor windings and the surface of the core for heat exchange, absorbing heat through heat conduction and the specific heat of air.

[0020] Internal water cooling: Cooling water flows directly through the stator and rotor windings, absorbing heat through heat conduction and the specific heat of water.

[0021] Evaporative cooling: Use fluorocarbon compounds with high insulation and appropriate boiling point as cooling medium. It is non-toxic, non-polluting, non-corrosive to metals and other parts of the motor, has good cooling capacity and high insulation, fireproof and arc extinguishing performance, and can inhibit the occurrence of electrical faults. It uses the latent heat of gasification of the fluid to achieve high heat exchange efficiency, low winding temperature rise, and no local overheating. It overcomes the inherent weaknesses of high operating pressure and serious damage caused by leakage of water internal cooling. Because its internal cooling method eliminates the need for a fan, wind friction is reduced, and the overall efficiency can be increased by 0.1-0.2%. It is easy to operate and maintain, saves materials, and is safe and reliable in operation.

[0022] Rotary seal: Rotary seal is a type of dynamic seal, which is used to seal rods, shafts, pins, rotary joints, etc. with rotating or swinging motion. It is a bidirectional sealing structure that can withstand pressure from both sides or alternating pressure.

[0023] Below through Figure 1 Describe the system implementation plan in detail.

[0024] like Figure 1As shown in the figure, in the system of the present invention, the rotating shaft 1, the rotor bracket 2, the rotor yoke and the rotor pole together constitute the rotor structure of the traditional motor. The rotor bracket 2 is sleeved on the rotating shaft 1. Some motors do not have a rotating shaft, but the rotating shaft 1 and the rotor bracket 2 are combined into the rotor center body. The outer periphery of the rotor bracket 2 is a circular ring-shaped yoke, which is not shown in the figure and is represented by the rotor bracket 2. The rotor pole is composed of a pole core and a pole coil 5, and is evenly distributed on the outer circumference of the yoke. The pole body 3 and the pole shoe 4 together constitute the pole core of the motor. In some motors, the pole body 3 and the pole shoe 4 are integrated; in other motors, the yoke and the pole body 3 are integrated. The pole core is sometimes formed by laminating thin steel plates, and sometimes by processing a whole piece of solid magnetic conductive material. The pole coil 5 is nested on the pole body 3 and fixed by a pole support plate (not shown in the figure).

[0025] In the evaporative cooling rotor of the vertical motor, the structure has changed to a certain extent. The condenser 6 is fixed on the rotating shaft 1 or the rotor bracket 2 and rotates with the rotor. The sealing liquid box 7 is a closed cavity, in which the magnetic pole coil 5 is placed with a gap, and the two are insulated from each other. The radial layout of the condenser 6 and the sealing liquid box 7 on the rotor satisfies that the radial position of the sealing liquid box 7 is larger than the condenser 6. The space between the magnetic pole coil 5 and the sealing liquid box 7 is filled with liquid medium, and when the rotor does not rotate, the liquid level of the liquid medium is higher than the magnetic pole coil 5, so that the magnetic pole coil 5 is in a state of being completely immersed in the liquid medium. A connection port is opened at the top of the sealing liquid box 7, and the position of the connection port in the vertical direction is higher than the liquid level of the liquid medium inside the sealing liquid box 7. A connection port is opened on the side of the condenser 6. One end of the connecting pipe 8 is connected to the upper connection port of the sealing liquid box 7, and the other end is connected to the side connection port of the condenser 6.

[0026] In specific applications, the condenser 6 can use water or air as the secondary cooling medium. If water is selected as the secondary cooling medium, the cooling water can enter through the shaft extension end on one side through the shaft side liquid inlet and then be discharged through the shaft extension end on the other side.

[0027] In specific applications, a connecting pipe is set between the top of the sealing liquid box and the condenser. Multiple sealing liquid boxes 7 can share one condenser 6 to form a parallel structure, or each sealing liquid box 7 can use a single condenser 6 to form an independent small system, or one sealing liquid box 7 can be connected to multiple condensers 6.

[0028] In a specific application, the connecting pipe 8 provided between the sealing liquid box 7 and the condenser 6 is in the shape of a hollow tube, and its outer cross section and inner hole cross section may be circular, rectangular or polygonal.

[0029] In a specific application, the connecting pipe 8 between the sealing liquid box 7 and the condenser 6 may be a single pipe or multiple pipes.

[0030] When the motor is running, the heat generated by the power supply to the pole coil 5 is absorbed by the liquid medium. The temperature of the liquid medium continues to rise, and when it reaches the boiling point, a boiling phase change occurs. The gaseous medium generated by the phase change enters the condenser 6 through the connecting pipe 8 and is cooled until it is liquefied. The condensed liquid medium also flows back to the sealing liquid box 7 through the connecting pipe 8 under the centrifugal force of the rotating rotor, thus completing a cycle. During the operation of the motor, this cooling cycle is repeated to ensure that the pole coil 5 operates stably at a suitable temperature.

[0031] The characteristics of this type of structure are: a) All sealing surfaces are static seals, and the sealing solution is mature and reliable; b) The abundant space inside the rotor bracket is used to place the condenser, optimizing the overall structure; c) The condensed liquid medium automatically flows back to the sealing liquid box from the condenser using the centrifugal force of the rotor rotation, realizing pump-free self-circulation; d) The condenser and the sealing liquid box only need to be connected through the connecting pipe on the top, avoiding the communicating vessel effect caused by the return liquid from the bottom, thereby improving the utilization rate of the cooling medium.

[0032] The sealing liquid box 7 is a box-type structure, and the interior is filled with liquid medium. The magnetic pole coil 5 is installed inside the sealing liquid box 7 and is completely immersed in the liquid medium.

[0033] like Figure 2 , 3 As shown in Figure 4, the lower cover plate 27, outer box 28, inner box 29 and upper cover plate 30 in the sealing liquid box 7 are made of insulating material or non-magnetic metal material treated with insulation. The four are integrated into a ring-shaped closed box structure and are fixed on the pole core. The pole coil 5 and the pole support plate 31 are loaded into the sealing liquid box together and immersed in the liquid medium. The top of the sealing liquid box 7 is provided with a connection port, and its position is determined by the actual situation during the design. The position marked in the figure is only for reference. The external electrical connection of the pole coil 5 is realized by an adapter plate arranged on one or several walls of the sealing liquid box 7, which is not drawn in the figure. This figure is a basic principle structure of the sealing liquid box 7, and the specific structure can be flexibly modified and appropriately deformed during the design.

[0034] The present invention discloses an immersion evaporative cooling system suitable for a vertical motor rotor, and its technical solution consists of four parts: a condenser, a connecting pipe, a magnetic pole coil, and a sealing liquid box. In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0035] Figure 5 An embodiment of the present invention.

[0036] The condenser 6 is mounted on the rotor support 2 and rotates with the rotor support 2. The condenser 6 uses water as the secondary cooling medium. The cooling water flows into the rotating water receiving tray 42 through the static water inlet pipe 41, and then flows into the condenser 6 through the water distribution pipe on the outer diameter of the rotating water receiving tray 42. The cooling water discharged from the bottom of the condenser 6 flows into the static water-splitting box 43.

[0037] Sealing liquid box 7 adopts Figure 2 The structure shown. The pole coil 5 is placed in the sealing liquid box 7 and immersed in the liquid medium, and the liquid level of the liquid medium is higher than the pole coil 5. A connection port is provided on the top of the sealing liquid box 7. The temperature of the liquid medium rises after absorbing the heat emitted by the pole coil 5 in the sealing liquid box 7. When the temperature of the liquid medium reaches the evaporation point, a gasification phase change occurs to generate a gaseous medium, and the gaseous medium flows from the sealing liquid box 7 to the condenser 6 through the connecting pipe 8. The condensed liquid medium flows out from the connecting hole at the bottom of the condenser 6 under the centrifugal force of the rotating rotor, and flows back to the sealing liquid box 7 through the connecting pipe 8, thus completing a cycle. During the operation of the motor, this cooling cycle is repeated to ensure that the pole coil 5 operates stably at a suitable temperature.

Claims

1. An immersion evaporative cooling system suitable for a vertical motor rotor, characterized in that: The invention comprises a condenser, a magnetic pole coil, a sealing liquid box and a connecting pipe, wherein the magnetic pole coil is placed inside the sealing liquid box, and the inside of the sealing liquid box is perfused with a liquid medium so that the magnetic pole coil is completely immersed in the liquid medium, that is, the liquid level of the liquid medium is higher than the magnetic pole coil, and the top of the sealing liquid box is connected to the condenser through a connecting pipe, and the gaseous medium generated inside the sealing liquid box flows to the condenser through the connecting pipe, and the liquid medium generated after condensation in the condenser also flows back to the sealing liquid box through the connecting pipe, so that only a connecting pipe needs to be set between the top of the sealing liquid box and the condenser to realize the two-way flow of the liquid medium and the gaseous medium at the same time, without the need for a connecting pipe between the bottom of the sealing liquid box and the condenser. A separate liquid return pipe is provided; when the rotor is not rotating, the magnetic pole coil is completely immersed in the liquid medium; when the rotor rotates, the magnetic pole coil is heated, the liquid medium absorbs heat and vaporizes, and the gaseous medium flows from the sealing liquid box to the condenser along the connecting pipe under the action of the pressure difference, and the liquid medium produced after condensation in the condenser flows back to the sealing liquid box from the condenser along the connecting pipe under the action of the centrifugal force generated by the rotation of the rotor, thereby realizing self-circulation without the need for a circulating pump. In this way, only a connecting pipe needs to be provided between the top of the sealing liquid box and the condenser, and the flow of the gaseous medium to the condenser and the flow of the liquid medium to the sealing liquid box are realized at the same time, which simplifies the design of the rotor evaporative cooling system and greatly improves the reliability of the vertical motor.

2. The immersion evaporative cooling system for a vertical motor rotor according to claim 1 is characterized in that: The radial layout of the condenser and the sealing liquid box on the rotor satisfies that the radial position of the sealing liquid box is larger than that of the condenser.

3. The immersion evaporative cooling system for a vertical motor rotor according to claim 1 is characterized in that: The top of the sealing liquid box is provided with a connection port connected to a connection pipe, and the vertical position of the connection port is higher than the liquid level of the liquid medium inside the sealing liquid box.

4. The immersion evaporative cooling system for a vertical motor rotor according to claim 1 is characterized in that: The connecting pipe is one or more.

5. The immersion evaporative cooling system for a vertical motor rotor according to claim 1 is characterized in that: The connecting pipe is in the shape of a hollow tube, and its outer cross section and inner hole cross section are circular, rectangular or polygonal.

6. The immersion evaporative cooling system for a vertical motor rotor according to claim 1, characterized in that: The connecting pipeline is a sealing liquid box connected to a condenser, or a sealing liquid box connected to multiple condensers, or multiple sealing liquid boxes connected to one condenser.

7. The immersion evaporative cooling system for a vertical motor rotor according to claim 1 is characterized in that: The cooling medium is sealed and stored in the sealing liquid box on the rotor, the connecting pipe and the condenser. It does not need to be injected into the rotor from outside the rotor during the rotation of the rotor, and it will not leak outside the rotor during the rotation of the rotor.

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