Demagnetization system and method for magnet elements of a wind turbine generator component

Abstract

A demagnetization system for demagnetizing magnet elements (10) of a wind turbine generator component is provided. Each magnet element (10) comprises at least one permanent magnet block (15). The demagnetization system (100) comprises at least one heating station (21, 22), wherein each heating station comprises an induction heater (30) configured to heat a magnet element (10) and an automatic transport system (50) configured to transport each magnet element (10) to each of the at least one heating station (21, 22), wherein the demagnetization system (100) is configured to heat the magnet element (10) at each heating station (21, 22) by means of the respective induction heater (30).

Description

[0001] Description

[0002] Demagnetization system and method for magnet elements of a wind turbine generator component

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to a demagnetization system for demagnetizing magnet elements of a wind turbine generator component and to a respective demagnetization method.

[0005] BACKGROUND

[0006] Over the past years, the size of wind turbines and their output power has been increasing significantly. Modern high power wind turbines include direct drive wind turbines in which the generator rotor is directly coupled to the wind turbine rotor without intervening gearbox. Such direct drive generators generally employ permanent magnets, usually on the generator rotor. For an exemplary wind turbine, six tons of NdFeB (neodymium iron boron) permanent magnets may be used on the generator rotor. It is desirable to re-use permanent magnet material and in particular to recover such permanent magnet material at the end of life of respective wind turbine generators .

[0007] Such recovery however faces several difficulties. To re-use material of permanent magnets, the permanent magnets generally need to be demagnetized. Demagnetization may be performed by heating the permanent magnets up to the Curie temperature. For example, NdFeB permanent magnets may be heated up to 350°C for demagnetization. The magnet elements used in wind turbine generators generally have a significant size, such as about 100x20x70 mm. The inventors have found that for demagnetizing a respective magnet element, the element can be placed in an oven and can be heated for approximately 40 minutes, which is required for a magnet element to reach a stable temperature throughout. Such way of demagneti zing a magnet element is thus timeconsuming . Further, a relatively large amount of energy may be required for the heating . Even further, it may not be possible to place several modules into the oven, since high forces develop between magnet elements , which may damage equipment and may be a risk to the operators operating the equipment . Demagneti zation may thus be inef ficient and timeconsuming . Using equipment similar to a magneti zer for providing demagneti zation is generally di f ficult , since it requires the magnet elements to be disassembled, which is di f ficult to achieve as long as the permanent magnet blocks inside the magnet element are still magneti zed . It is thus desirable to facilitate the demagneti zation of such magnet elements .

[0008] Document WO 2017 / 079183 Al discloses a system to separate and recycle magnets from an article of manufacture that uses a separating device removing the magnet and a portion of the article and a heating device to demagneti ze the magnets .

[0009] SUMMARY

[0010] Accordingly, there is a need to mitigate at least some of the drawbacks mentioned above and to improve the demagneti zation of magnet elements . It is in particular desirable to increase the ef ficiency of the demagneti zation and to reduce the risk for personnel that performs the demagneti zation operation .

[0011] This need is met by the features of the independent claims . The dependent claims describe embodiments of the invention .

[0012] According to an embodiment of the invention, a demagneti zation system for demagneti zing magnet elements of a wind turbine generator component is provided . Each magnet element comprises at least one permanent magnet block . The demagneti zation system comprises at least two heating stations , wherein each heating station comprises an induction heater configured to heat a magnet element. It further comprises an automatic transport system configured to transport each magnet element to each of the at least two heating stations, wherein the demagnetization system is configured to heat the magnet element at each heating station by means of the respective induction heater.

[0013] Such system may provide a fast and efficient demagnetization of the magnet elements. In particular, by such induction heating, an efficient heat transfer to the magnet element may be achieved, and the heating time may be reduced significantly. Further, by providing heating at one or more different heating stations, and in particular by the magnet element passing one heating station after the other and being heated therein, the throughput of the demagnetization system may be increased significantly, and the overall time required to demagnetize a magnet element may further be reduced. By providing a respective automatic transport, the magnet elements may continuously be processed and demagnetized. As this may avoid the need for the magnet elements to be handled by service personnel, the safety is furthermore improved. Even a relatively large magnet element of a wind turbine generator component (abbreviated herein as generator component or component) may thus be demagnetized efficiently and safely. A large scale demagnetization becomes feasible.

[0014] According to the invention, at least two heating stations are provided, and the automatic transport system is configured to transport each magnet element consecutively to each of the at least two heating stations. For example, 2, 3, 4, 5 or more heating stations may be provided.

[0015] The system may be configured to expose the magnet element at each heating station to an induction heating for a (predetermined) period of time. The period of time may for example be longer than 1 second and shorter than 5 minutes, e.g. between 5 or 10 seconds to 1 minute, for example between 5 or 10 seconds and 40 seconds. The magnet element may thus remain only for a relatively short period of time , such as 30 seconds , at the heating station . The duration of the demagneti zation process for a magnet element may thus be reduced signi ficantly .

[0016] The transport system may for example be configured to transport the magnet element to the heating station and to stop transportation for a period of time over which the magnet element is to be heated in the heating station ( e . g . for the period of time mentioned above for which it is exposed to induction heating) . A high ef ficiency of the induction heating and a good exposure of the magnet element to the electromagnetic fields of the induction heater may thus be ensured . The automatic transport system may for example be configured to transport the magnet element into the heating station, stop for the predetermined period of time , and then continue transportation until the next magnet element reaches the heating station . The magnets may thus be transported intermittently by the automatic transport system .

[0017] In other implementations , it is also conceivable to adj ust the speed of the automatic transport system and the spatial extension of the induction heater in the transportation direction such that the magnet element passes through the heating station, in particular the induction heater, in a period of time over which the magnet element is to be heated in the heating station . The automatic transport system, such as a conveyor, may run continuously in such configuration .

[0018] The spacing of magnet elements on the transport system ( e . g . , the spacing between carriers on a belt or chain of the transport system) may be configured to correspond to the spatial distance between the heating stations . For example , the spacing between the heating stations may be an integer multiple , e . g . 1 , 2 , 3 , ..., of a spacing between the magnet elements on the automatic transport system . Thereby, it may be ensured that when a magnet element is present in a first heating station, a magnet element is also present in the remaining heating stations , so that these magnet elements may be heated simultaneously in each heating station .

[0019] The transport system may for example comprise a conveyor having plural carriers , and each carrier may be configured to receive a magnetic element . The conveyor may be configured to transport the carriers to , into or through the one or more heating stations .

[0020] The demagneti zation system may be configured such that each magnet element is heated at the at least one heating station to a temperature at which the permanent magnet block of the magnet element becomes demagneti zed . It should be clear that this temperature may be di f ferent for di f ferent materials of the permanent magnet block . The duration of exposure to the heating and the temperature to be reached by the magnet element may be adj usted accordingly . The temperature to be reached may in particular be at or above the Curie temperature of the material of the permanent magnet block . For example , the heating power of the induction heater, the predetermined period of time for induction heating, and / or the number of heating stations may be adapted to reach the respective temperature of the magnet element .

[0021] The period of time of induction heating the magnet element may be similar or the same for each heating station .

[0022] In an embodiment , the demagneti zation system comprises at least three heating stations , it may comprise three , four, five or more heating stations . By providing more heating stations , the time that the magnet element has to spend at each heating station may be reduced, so that an overall faster processing may be achieved by heating more magnet elements in parallel .

[0023] The transport system may be configured to transport , in operation, a magnet element simultaneously to each heating station, and the demagneti zation system may further be configured to simultaneously provide induction heating of these magnet elements at each of the heating stations .

[0024] The transport system may be configured to automatically place a magnet element within the induction heater, and to automatically take out a heated magnet element from an induction heater . For this purpose , the transport system may for example comprise a conveyor with one or more actuators to raise and lower carriers on which the magnet elements are placed .

[0025] The induction heater may comprise an induction coil wound around a space in which the magnet element is arranged when the magnet element is located at the respective heating station . By winding the induction coil around this space , the magnet element may thus be positioned within the coil when being heated . The ef ficiency of the heating may thereby be improved, and the temperature of the magnet element may be increased faster .

[0026] The induction coil preferably comprises less than five , three or two windings ( or turns ) . For example , the induction coil may comprise a single winding ( or turn) . The induction coil may for example be a single solid copper conductor . Such configuration of the induction heater provides a high heating power and allows heating with large currents . A fast and ef ficient heating of the magnet element thereby become possible .

[0027] The induction heater may further comprise a cooling system, such as a liquid system, which cools an induction coil of the induction heater . Cooling medium may for example be water or oil . The cooling system may be configured to convey a cooling medium in a front end and / or a rear end of the induction heater around the space . An ef ficient cooling of the induction coil may thereby be achieved while keeping the induction heater small . The demagneti zation system may further comprise at least one resting station, and the transport system may be configured to transport each magnet element to the resting station after passing the at least one heating station . A resting station may for example be provided after each heating station . At the resting station, the magnet element may not further be processed and may be allowed to equali ze its internal temperature . As the magnet elements may be on the same conveyor, the resting station may simply be a station at which no further processing is provided, so that while magnet elements are heated in each heating station, the magnet element at the resting station remains there for the same predetermined period of time and equali zes its internal temperature . An ef ficient demagneti zation may thereby be achieved .

[0028] The transport system may comprise an interface towards an extraction system configured to extract the magnet elements from the wind turbine generator component . Additionally or alternatively, the transport system may comprise an interface to a separation system configured to disassemble the magnet elements . It may thus be possible to integrate the demagneti zation system into an automated magnet element recycling system that recycles magnet elements of the generator component .

[0029] For example , the demagneti zation system may be a modular system that is configured to interface a respective magnet extraction module that extracts the magnet elements from the generator component and / or to interface a separation module that provides disassembly of the demagneti zed magnet elements , for example by removing an enclosure from the permanent magnet blocks . An automated and high throughput continuous recycling of magnet elements may thereby be achieved .

[0030] Each magnet element may comprise an enclosure , such as a housing or encapsulation around the at least one permanent magnet block . Such housing may for example comprise a base plate and a cover . The at least one permanent magnet block may be adhered ( e . g . by means of an adhesive ) to the base plate and / or to the cover . Such configuration of the magnet element facilitates its handling when used in the generator component and further protects the magnet blocks .

[0031] The demagneti zation system may further comprise an opening station with a perforation device configured to provide an opening in the enclosure of the magnet element . By automatically providing the opening in the enclosure , disassembly of the magnet element while the permanent magnet blocks are still magneti zed can be avoided, without any risk for service personnel . Further, by opening the enclosure , any fumes or gases that are generated by evaporation of any adhesive present in the enclosure due to the inductive heating can be released . Destruction of the enclosure due to an increase in internal pressure can thereby be avoided, which further improves the safety and avoids damage to the demagneti zation system . Furthermore , by evaporation and / or burning of the adhesive , the at least one magnet block is released from its adhesive connection to the base plate and / or cover, so that a subsequent disassembly of the magnet element is facilitated .

[0032] The perforation device may for example comprise at least one of a cutter, a saw, a drill , a milling tool , a mechanical cutter, plasma cutter, water j et cutter, or electrical discharge cutter, and a welding tool . The perforation device may be automatically controlled by the demagneti zation system .

[0033] The transport system may be configured to transport the magnet element to the opening station prior to transporting the magnet element to a first of the one or more heating stations . It may thus be ensured that the enclosure of each magnet element is opened before reaching the first heating station . In an exemplary implementation, the transport system may comprise two conveyors , wherein a first conveyor is configured to transport the magnet elements to the opening station and a second conveyor is configured to transport the magnet elements to the one or more heating stations . The two conveyors may meet at a point at which the magnet elements are trans ferred from the first conveyor to the second conveyor .

[0034] The demagneti zation system may further comprise a gas treatment system configured to treat gases and / or fumes emitted when heating the magnet elements in the one or more heating stations . When evaporating or burning adhesive comprised in the enclosures of the magnet elements , the resulting fumes / gases may thus be cleaned prior to being released into the environment . Such gas treatment system may for example comprise piping having suction openings adj acent to the at least one heating station, which may allow the generated gases to be removed by suction . It may further comprise respective blowers arranged in the piping to cause the suction, filters , and other gas cleaning equipment through which one or more blowers convey the gases / fumes . It may further include an exhaust pipe through which the cleaned gases are released into the environment .

[0035] The demagneti zation system may further comprise an induction generator configured to generate an electrical drive signal for driving the induction heater . A common induction generator driving each induction heater, or individual induction generators for each induction heater may be provided . The induction generator may for example generate a high frequency high current electrical signal that is applied to the induction coil and that drives the induction heating .

[0036] The demagneti zation system may further comprise a control system configured to control the one or more heating stations and the transport system . The control system may be configured to automatically perform the steps of transporting the magnet element to a first heating station by means of the transport system; heating the magnet element at the first heating station by means of the respective induction heater ; and optionally transporting the magnet element to a second heating station by means of the transport system; and heating the magnet element at the second heating station by means of the respective induction heater . Respective steps may be performed i f further heating stations are present . The control system may in particular perform these steps automatically for plural magnet elements . It may thus be configured to continuously demagneti ze plural magnet elements . The control system may further control the perforation device to automatically open the enclosure of each magnet element prior to reaching the first heating station . For example , the control system may control the demagneti zation system such that each magnet element subsequently passes the perforation device for being opened, the first , second and third heating stations , and optionally the resting station after each heating station . A fast , continuous and high throughput demagneti zation may thus be achieved .

[0037] Each magnet element may be a magnet element that has been extracted from a wind turbine generator component , e . g . a generator rotor, having a nominal power rating of at least 250kW, preferably at least 500kW, at least 1MW, or at least 2MW . The wind turbine generator component may be a generator rotor of a direct drive generator . A direct drive generator may be configured to be mechanically connected to a wind turbine rotor of the wind turbine without intervening gearbox .

[0038] In an embodiment , the demagneti zation system further comprises a shipping container . The transport system and the one or more heating stations may be disposed in the shipping container . They may in particular be operable within the shipping container . Further elements disclosed herein of the demagneti zation system may likewise be disposed in the shipping container, such as the opening station, the resting station, and / or the gas treatment system . Additionally or alternatively, the container may comprise a control room separated by an internal wall from the processing room in which the one or more heating stations are provided . Safety of the service personnel operating the demagneti zation system may thus be improved . Such control room may for example comprise the induction generator and the control system . The container may for example be a standard container, such as a 20 , 24 , or 40 foot container . It may in particular be an intermodal container, e . g . a container under ISO standard 668 : 2020 or comparable standard .

[0039] According to another embodiment of the invention, a method of demagneti zing magnet elements of a wind turbine generator component is provided . Each magnet element comprises a permanent magnet block . The method comprises transporting, by means of an automatic transport system, a magnet element to a first heating station; and heating the magnet element by means of an induction heater of the first heating station . Optionally, the method may further comprise transporting, by means of the transport system, the magnet element to a second heating station; and heating the magnet element by means of an induction heater of the second heating station . By such method, advantages similar to the ones outlined further above may be achieved . In particular, the steps may be repeated continuously for plural magnet elements , thus allowing the demagneti zation of plural magnet elements in a fast , safe , and ef ficient way .

[0040] The method may comprise further steps , such as one or more of the following : receiving a magnet element from an extraction system; opening an enclosure of the magnet element prior to heating; transporting the magnet element to a third or further heating stations and heating the magnet element at these using induction heating; allowing the magnet element to rest for a predetermined period of time at a resting station; and / or transporting the magnet element towards a separation system configured to disassemble the magnet element . The method may include one or more of these steps in any combination .

[0041] The method may further comprise any of the steps described herein with respect to the demagneti zation system . Further, the control system may be configured to perform any of the methods described herein .

[0042] It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the scope of the present invention . In particular, the features of the di f ferent aspects and embodiments of the invention can be combined with each other unless noted to the contrary .

[0043] BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The foregoing and other features and advantages of the invention will become further apparent from the following detailed description read in conj unction with the accompanying drawings . In the drawings , like reference numerals refer to like elements .

[0045] Fig . 1 is a schematic drawing illustrating a demagneti zation system according to an embodiment .

[0046] Figs . 2 is a schematic drawing illustrating a magnet element according to an embodiment .

[0047] Fig . 3 is a schematic drawing illustrating a demagneti zation system according to an embodiment .

[0048] Fig . 4 is a schematic drawing showing details of the demagneti zation system of figure 3 . Fig . 5 is a schematic drawing illustrating the heating of a magnet element at a heating station and an induction heater according to an embodiment .

[0049] Fig . 6 is a schematic drawing showing a gas treatment system of the demagneti zation system of figure 3 .

[0050] Fig . 7 is a flow diagram illustrating a method of demagneti zing magnet elements according to an embodiment .

[0051] DETAILED DESCRIPTION

[0052] In the following, embodiments of the invention will be described in detail with reference to the accompanying drawings . It is to be understood that the following description of the embodiments is given only for the purpose of illustration and is not to be taken in a limiting sense . It should be noted that the drawings are to be regarded as being schematic representations only, and elements in the drawings are not necessarily to scale with each other .

[0053] Rather, the representation of the various elements is chosen such that their function and general purpose become apparent to a person skilled in the art . As used herein, the singular forms "a, " "an, " and "the" are intended to include the plural forms as well , unless the context clearly indicates otherwise . The terms "comprising, " "having, " " including, " and "containing" are to be construed as open-ended terms ( i . e . , meaning " including, but not limited to , " ) unless otherwise noted .

[0054] Fig . 1 schematically illustrates a demagneti zation system 100 that includes a transport system 50 and three heating stations 21 , 22 and 23 . The transport system 50 comprises an interface 56 towards an extraction system that extracts magnet elements 10 from a wind turbine generator component , such as a generator rotor of a direct drive generator . Fig . 2 schematically illustrates a magnet element 10 which includes one or more permanent magnet blocks 15 . These are optionally housed in an enclosure , casing, or other encapsulation; magnet element 10 may thus also be designated as a magnet module . In the present example , magnet element 10 includes a base plate 11 , e . g . a steel plate , and a cover 17 which may be made of sheet metal . Permanent magnet block 15 may be adhered to base plate 11 and / or cover 17 by means of an adhesive 12 , which is provided in the present example on the base plate 11 . Base plate 11 may hold the magnet element within a slot of the generator component and the extraction system may extract the magnet element 10 therefrom and supply it to the interface 56 of transport system 50 .

[0055] Transport system 50 includes a conveyor 51 , which may for example include a conveyor chain, conveyor belt and / or guide rails . In the present example , it includes carriers 52 that are driven by a conveyor chain or belt , and which may run on respective guide rails . As illustrated, each carrier 52 takes up a respective magnet element 10 , which is then transported by the conveyor 51 through the demagneti zation system 100 . It should be clear that any conveyor known in the art may be employed in system 100 , so that no further details are given here .

[0056] Each heating station 21 , 22 , 23 comprises an induction heater 30 . Each induction heater is driven by an induction generator 35 , which may generate a respective high frequency ( kilohertz range ) drive signal capable of providing high alternating current in an induction coil 31 ( Fig . 5 ) of the induction heater . The induction heater thereby generates a pulsed magnetic field that induces currents in a magnet element positioned within the respective heating station . The magnet element 10 can thus be heated rapidly to high temperatures . By subsequently passing several heating stations , at each of which inductive heating is applied to the magnet element 10 , a temperature of the magnet element exceeding the Curie temperature may be achieved, so that the magnet element is demagnetized (in particular the permanent magnet block 15) . The present example provides three heating stations, although fewer or more heating stations, e.g. one, two, three, four, five, six or more, may be provided.

[0057] Magnet element 10 may consist of one or more permanent magnet blocks 15, but may also comprise an enclosure, as explained above with respect to Fig. 2. The demagnetization system 100 may include an opening station 40 at which the enclosure is opened. Opening station 40 may include a cutter 41 which may be provided as a plasma cutter or plasma torch, which cuts open the enclosure, for example by cutting the cover 17. Besides cutters, other perforation devices may be employed by opening station 40, such as mechanical cutters, drills, water jet or electrical discharge cutters or drills, milling tools and the like. Plural holes and / or slits may be cut into the enclosure of magnet element 10.

[0058] During heating in heating stations 21 to 23, the adhesive 12 or any other coating comprised in magnet element 10 may burn and / or evaporate, thereby increasing the pressure in the enclosure, which may lead to an explosion thereof. By opening the enclosure at the opening station 40, such gases and fumes can be released from the enclosure through the opening cut by cutter 41. Safety may thus be increased.

[0059] Fig. 5 illustrates an exemplary implementation of an induction heater 30. The induction heater comprises an induction coil 31. In the present example, induction coil 31 surrounds the space in which the magnet element 10 is arranged during heating, and into which the magnet element 10 is placed when being transported by the transport system 50. By such arrangement of the induction coil around the magnet element 10 during heating, the efficiency of the heating is increased significantly, and high temperatures can be achieved within the magnet element 10 even within a short period of time. For example , the induction coil 31 may comprise only few turns , for example three , two , or only a single turn, as in the example of Fig . 5 . In the exemplary implementation, the induction coil comprises a solid copper conductor that provides a single winding . High currents can thus be achieved and accordingly a high pulsed magnetic field which quickly heats up magnet element 10 .

[0060] The induction heater 30 may further comprise a cooling system 32 through which a cooling liquid is preferably circulated, such as water . A conduit may for example be provided at an end of induction heater 30 through which the coolant is circulated . The induction coil 31 may thus be cooled ef ficiently . Plural such cooling conduits may be provided, e . g . at each open end of the induction heater 30 .

[0061] Fig . 5 further illustrates gases 36 that escape from the enclosure of magnet element 10 and that are due to the burning of the adhesive 12 . Deformation of the magnet element 10 and the risk of explosion, and subsequent damage to the equipment of system 100 may thus be avoided .

[0062] Returning to Fig . 1 , transport system 50 may continuously or intermittently transport the magnet elements 10 by conveyor 51 through the di f ferent stations . For example , once a magnet module 10 has reached a heating station 21 to 23 , transportation may stop for a predetermined amount of time during which the magnet element is heated in the respective heating station . The amount of time is preferably less than five minutes , it may for example be between 1 second and 5 minutes , preferably between 5 seconds and 1 minute . For example , it has been found that for a magnet module having a si ze similar to the one outlined in the introduction, three heating stations at each of which the magnet element 10 is heated for about 30 seconds is suf ficient to reach a temperature above the Curie temperature and to demagneti ze the permanent magnet material . The total heating time may thus only be 90 seconds and is thus signi ficantly faster than conventional demagneti zation methods . It should be clear that the time of heating in each station is to be determined by the number of heating stations , the si ze of the magnetic modules , and the heating power of the induction heaters at each heating station .

[0063] The distance between the heating stations 21 , 22 , 23 is preferably chosen so that it is an integer multiple of the distance between two of the magnet elements 10 as transported by conveyor 51 , e . g . the distance between two carriers 52 in direction of transportation . In the example of Fig . 1 , the distance between two heating stations is twice the distance between two carriers , so that when a magnet element 10 is located in the first heating station 21 , a magnet element is likewise located in the second and third heating stations 22 , 23 . Thus , all heating stations can simultaneously heat magnet elements for the predetermined duration . After the predetermined time period has passed, the transport system 50 transports the next element into the heating station . A continuous demagneti zation of magnet elements 10 is thus possible and can be performed in a time-ef ficient manner .

[0064] It should be clear that other solutions are also conceivable , such as carriers that are disconnected from the conveyor chain or belt while at the respective heating station, and engaging the conveyor chain or belt again to be transported to the next heating station . In such and similar configurations , the distance between the magnet elements on the conveyor 51 may be arbitrary, and the distance between the heating stations may be chosen as desired .

[0065] Demagneti zation system 100 may for further comprise at least one resting station 45 at which a magnet element 10 may rest (while other magnet elements are being heated) without further processing . In the example of figure 1 , a resting station 45 is provided after each heating station . Resting at the resting station 45 may allow the temperature within the magnet element 10 to equali ze . It has been found that this further improves the demagneti zation of the magnet element . The period of time which the magnet element spends at the resting station 45 may thus correspond or be equal to the amount of time during which the magnet element is heated at each heating station . As mentioned above , more flexible transport systems 50 are also conceivable , in which individual times may be provided for each heating station, as well as for the opening station 40 and the resting station 45 .

[0066] Transport system 50 may further comprise an interface 57 towards a separation system . As the permanent magnet block 15 is demagneti zed when reaching interface 57 , such separation system may be used to separate the permanent magnet block 15 from the enclosure , in particular from the base plate 11 and cover 17 . Due to the evaporation and burning of adhesive 12 , such separation is facilitated by demagneti zation system 100 .

[0067] Demagneti zation system 100 further comprises a control system 110 that controls the transport system 50 and the heating stations 21 to 23 . It may for example control respective induction generators 35 , or a common induction generator 35 to control heating by induction heaters 30 . Further, it may control the transport of magnet elements by conveyor 51 and may accordingly cause the conveyor 51 to stop once the carrier with the magnet element 10 has reached a respective station, such as the opening station 40 or the heating station 21 to 23 . Control system 110 may further control the perforation device 41 to open the enclosure of magnet element 10 . Control system 110 may thus cause the conveyor 51 to stop for a predetermined amount of time so that magnet elements at heating stations 21 to 23 are heated, a magnet element at opening station 40 is cut open and a magnet element at resting station 45 rests for temperature equali zation . Once the predetermined amount of time has passed, control system 110 may cause conveyor 51 to transport the magnet elements 10 one step further . Control system 110 may comprise a processing unit 111 and a memory 112 . Memory 112 may comprise control instructions that are executed by processing unit 111 . By executing the instructions by processing unit 111 , the control system 110 may cause the demagneti zation system 100 to perform any of the methods described herein . Processing unit 111 may include a microprocessor, an application speci fic integrated circuit , a digital signal processor, or the like . Memory 112 may include any type of volatile and non-volatile memory, such as RAM, ROM, Flash-Memory, or the like . Control system 110 may comprise any other elements common to a computing system, such as respective input and output interfaces for receiving information and sending control signals , as well as a user interface .

[0068] Fig . 3 illustrates a particular implementation of the demagneti zation system 100 of Fig . 1 , so that the above explanations are equally applicable . Transport system 50 includes the conveyor 51 as well as a second conveyor 55 which provides the interface 56 to the extraction system . Conveyor 55 is a belt conveyor and magnet elements 10 arriving via belt conveyor 55 are trans ferred onto the carriers 52 of the conveyor 51 . In Fig . 3 , guide rails 53 and a conveyor belt 54 that transports carriers 52 and that runs in a circle are illustrated . Furthermore , the perforation device 41 is shown and is implemented as a plasma cutter in the present example . A magnet element 10 thus arrives at opening station 40 , where conveyors 55 , 51 stop, the enclosure is opened by perforation device 41 , and upon passing of the predetermined time period, both conveyors continue and the magnet element is trans ferred from conveyor 55 onto a carrier 52 of conveyor 51 . Transportation then continues on conveyor 51 to the first heating station .

[0069] This is illustrated in more detail in Fig . 4 . As can be seen, the induction heaters 30 of three heating stations 21 , 22 , 23 are arranged above the conveyor 51 , and the magnet elements 10 are transported via carriers 52 to the respective heating stations . In the situation shown in Fig . 4 , a magnet element is positioned by a carrier 52 within each induction heater 30 and is being heated for the predetermined period of time . Transportation then continues , wherein the magnet elements are transported to an optional resting station 45 , which may be provided after each heating station, and finally reach the interface 57 , at which they are trans ferred to the separation system, i f such is provided . Alternatively, the magnet elements 10 may also be collected in a container, for example i f they do not comprise an enclosure , or i f a respective enclosure is to be removed at another location .

[0070] For example , the conveyor 51 may cause the carrier 52 to be moved forward until the magnet element is arranged in the induction heater 30 . The conveyor may then be lowered so that the magnet element is supported in the induction heater and be driven backwards to retract the carrier so that the magnet element remains inside the induction heater, e . g . on an internal support . After the predetermined time period for heating, the conveyor may be moved forward again and the conveyor or carrier may be li fted so as to take up the heated magnet element . The conveyor may then be moved backwards to move out the magnet element 10 from the induction heater 30 . The carrier may then be lowered ( e . g . by lowering the conveyor ) so that the carrier and the magnet element 10 can pass underneath the induction heater 30 and can be transported to the next heating station . Respective actuators 58 , e . g . hydraulic / pneumatic cylinders , may be provided on the conveyor to li ft and lower the conveyor, as illustrated in figures 3 and 4 .

[0071] The magnet element may thus be placed within the induction heater by such transport device even i f the induction heater is a closed coil . Alternatively, the next carrier may push out the magnetic element from the induction heater onto the empty carrier that has been moved forward to receive the heated magnet element . Movement of the conveyor 51 and the carriers 52 may occur under control of control system 110 . In even other embodiments , the conveyor 51 may include a belt or chain that runs through the induction heaters , or may be a slat conveyor the slats of which run through the induction heaters . Such belt or slats are preferably non-conductive and heat resistant .

[0072] Figure 4 shows a respective situation in which carriers 52 have placed magnet elements in the respective induction heaters 30 and the carriers 52 have been retracted from the induction heaters during the heating phase (please see the empty carriers 52 in front of the induction heaters 30 ) . After the heating phase , the carriers 52 pick up again the respective magnet elements 10 from the induction heaters 30 and transport them to the next station .

[0073] In Fig . 4 , piping 61 of a gas treatment system is further shown, which can certainly be present also in the embodiment of Fig . 1 . The piping 61 includes suction openings 62 , by means of which fumes and gases that are emitted during the heating of the magnet elements 10 can be removed . Fig . 6 illustrates details of an exemplary gas treatment system 60 . The piping 61 is connected to a blower or fan 63 which causes an under-pressure in piping 61 and thus causes the exhaust fumes and gases to be sucked into piping 61 . The gases and fumes are further transported by blower 63 to a filter unit 64 , which may comprise the required filters for removing contaminants and harmful or environmental unfriendly gases from the air that is sucked through piping 61 . After cleaning, the filtered and cleaned air is exhausted via an exhaust pipe 65 . A further blower 63 may be provided between the filter and the exhaust pipe to account for the pressure reduction due to the filtering .

[0074] In Fig . 6 , further cutter equipment of the perforation device 41 is illustrated at reference sign 42 , such as a gas bottle comprising gas for a plasma torch and the respective apparatus . The demagneti zation system 100 may be provided in a shipping container, in particular a standard container, such as a 20 or 40 foot container . It may be configured to be operable inside the container . This has the advantage that the system can easily be transported to the location at which the recycling of magnets is required . The heating stations 21 to 23 may thus be arranged longitudinally along the length of the container . The second conveyor 55 may for example reach from the extraction system through the container wall into the container .

[0075] As illustrated in Fig . 6 , the gas treatment system 60 is provided inside the container 70 . It may be separated by a wall from the heating stations and the piping 61 may reach through the wall . The container may further include a control room that comprises for example the induction generator 35 and the control system 110 . The control room may be separated from the space in which heating stations 21 to 23 are located so that an operator in the control room cannot be harmed by the demagneti zation process . A compact modular system can thus be provided that is easily transportable and that further provides an increased safety for service personnel .

[0076] It should be clear that the gas treatment system 60 is optional , and may in particular not be necessary in situations where only magnet blocks 15 without enclosure , or magnet elements 10 with di f ferent types of encapsulation are demagneti zed .

[0077] Fig . 7 shows a flow diagram of an exemplary method that may be performed with the demagneti zation system 100 in any of the disclosed configurations . In step 71 , magnet elements are received from the extraction system, e . g . via interface 56 . An opening is provided in the enclosure of a received magnet element 10 at the opening station 40 in step 72 . One or several holes or slits may be provided in the cover 17 of the magnet element 10 by the perforation device 41 . In step 73 , the magnet element is transported to the first heating station 21 and it is heated by means of the induction heater 30 . In step 74 , the magnet element is transported to the first resting station 45 and is allowed to rest for temperature equali zation . In steps 74 and 75 , the magnet element 10 is then transported to the next heating station 22 and thereafter to the next resting station 45 , at which induction heating and temperature equali zation take place , respectively . In step 77 , the magnet element is transported to the third heating station 23 and again heated by induction heating . In step 78 , the magnet element is transported to the last resting station 45 and is allowed to rest for temperature equali zation . Finally, in step 79 , the magnet element is forwarded to the separation system, for example via the interface 57 .

[0078] It should be clear that several of the above recited steps of the method of Fig . 7 are optional . Steps 72 , 74 , 76 and 78 are for example optional as well as step 79 . Further, only one or two heating stations may be provided . Likewise , the magnet elements may be received from a di f ferent source other than an extraction system .

[0079] The method may be implemented by the control system 110 which may control the components of demagneti zation system 100 accordingly . The method may further comprise any of the steps described herein with respect to system 100 .

[0080] While speci fic embodiments are disclosed herein, various changes and modi fications can be made without departing from the scope of the invention . The present embodiments are to be considered in all respects as illustrative and non- restrictive , and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein .

Claims

Patent claims1. A demagnetization system for demagnetizing magnet elements (10) of a wind turbine generator component, wherein each magnet element (10) comprises at least one permanent magnet block (15) , wherein the demagnetization system (100) comprises : at least two heating stations (21, 22) , wherein each heating station comprises an induction heater (30) configured to heat a magnet element (10) ; and an automatic transport system (50) configured to transport each magnet element (10) to each of the at least two heating stations (21, 22) , wherein the demagnetization system (100) is configured to heat the magnet element (10) at each heating station (21, 22) by means of the respective induction heater (30) .

2. The demagnetization system according to claim 1, wherein the demagnetization system is configured to expose the magnet element (10) at each heating station (21, 22) to induction heating for a period of time, wherein the period of time is longer than 5 seconds and shorter than 5 minutes.

3. The demagnetization system according to claim 1 or 2, wherein the transport system (50) is configured to transport the magnet element (10) to the heating stations (21, 22) and to stop transportation for a period of time over which the magnet element (10) is to be heated in the heating station(21, 22) .

4. The demagnetization system according to any of the preceding claims, wherein the demagnetization system (100) is configured such that each magnet element (10) is heated by means of the at least two heating stations (21, 22) to a temperature at which the at least one permanent magnet block5. The demagnetization system according to any of the preceding claims, wherein the induction heater (30) comprises an induction coil (31) wound around a space in which the magnet element (10) is arranged when the magnet element is located at the respective heating station (21, 22) .

6. The demagnetization system according to claim 5, wherein the induction coil (31) comprises a single winding, wherein preferably, the demagnetization system further comprises an induction generator (35) configured to drive the induction coil (31) .

7. The demagnetization system according to any of the preceding claims, further comprising at least one resting station (45) , the transport system (50) being configured to transport each magnet element (10) to the at least one resting station (45) after passing at least one of the at least two heating stations (21, 22) , wherein the magnet element (10) is not further processed at the resting station (45) and is allowed to equalize its internal temperature.

8. The demagnetization system according to any of the preceding claims, wherein the transport system (50) comprises a conveyor (51) having plural carriers (52) , each carrier (52) being configured to receive a magnet element (10) , the conveyor (51) being configured to transport the carriers (52) to the at least two heating stations.

9. The demagnetization system according to any of the preceding claims, wherein the transport system (50) comprises an interface (56) towards an extraction system configured to extract the magnet elements (10) from the wind turbine generator component, and / or wherein the transport system (50) comprises an interface (57) to a separation system configured to disassemble demagnetized magnet elements (10) .

10. The demagnetization system according to any of the preceding claims, wherein each magnet element (10) comprisesan enclosure, wherein the demagnetization system (100) comprises an opening station (40) with a perforation device (41) configured to provide an opening in the enclosure of the magnet element (10) .

11. The demagnetization system according to claim 10, wherein the transport system (50) is configured to transport the magnet element (10) to the opening station (40) prior to transporting the magnet element to a first of the at least two heating stations (21) .

12. The demagnetization system according to any of the preceding claims, further comprising a gas treatment system (60) configured to treat gases and / or fumes emitted when heating the magnet elements (10) in one or more of the at least two heating stations (21, 22) .

13. The demagnetization system according to any of the preceding claims, further comprising a control system (110) configured to control the two or more heating stations (21, 22) and the transport system (50) , the control system (110) being configured to automatically perform the steps of: transporting a magnet element (10) to a first heating station (21) by means of the transport system (50) ; heating the magnet element (10) at the first heating station (21) by means of the respective induction heater (30) ; transporting the magnet element (10) to a second heating station (22) by means of the transport system (50) ; and heating the magnet element (10) at the second heating station (22) by means of the respective induction heater (30) .

14. The demagnetization system according to any of the preceding claims, wherein the demagnetization system (100) further comprises a shipping container (70) , the transport system (50) and the two or more heating stations (21, 22) being disposed in the shipping container (70) .

15. A method of demagnetizing magnet elements (10) of a wind turbine generator component, wherein each magnet element (10) comprises at least one permanent magnet block (15) , wherein the method comprises: transporting, by means of an automatic transport system (50) , a magnet element (10) to a first and a second heating station (21, 22) ; and heating the magnet element (22) by means of an induction heater (30) of the first and second heating stations(21, 22) .

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