A wind turbine blade air-heat de-icing system with flexible duct and a method for fixing and disassembling the flexible duct.

Abstract

This invention discloses a wind turbine blade air-thermal de-icing system with a flexible duct and a method for fixing and disassembling the flexible duct. The system includes a heater, a blower, and a duct. The duct is formed by connecting a rigid duct and a flexible duct. The air inlet of the heater is connected to the air outlet of the blower, and the air outlet of the heater is connected to the air inlet of the rigid duct. The air outlet of the rigid duct is connected to the air inlet of the flexible duct. The flexible duct is arranged inside the leading edge cavity of the blade, and several air guide holes are opened on the windward side of the flexible duct facing the blade. A hook is installed at regular intervals along the longitudinal axis of the blade web inside the leading edge cavity. Multiple fixing ropes are set on the flexible duct facing the leeward side of the blade corresponding to the hooks. The flexible duct is fixed to the blade web by the fixing ropes being inserted into the openings of the hooks. This invention can extend the duct to the blade tip, enhancing the de-icing effect at the blade tip, and can also create a new hot air return channel within the blade tip blockage, achieving the effect of air-thermal de-icing.

Description

Technical Field

[0001] This invention relates to de-icing of wind turbine blades, specifically to a wind turbine blade air-thermal de-icing system with a flexible duct and a method for fixing and disassembling the flexible duct. Background Technology

[0002] Currently, wind turbines located in mountainous areas of both the north and south are facing the problem of blade icing and inability to generate electricity in winter. Since there is no effective means to remove the ice from the blades, they can only wait for the weather to warm up and melt naturally, resulting in a huge loss of power generation. Moreover, icing has a serious impact on the safety, service life, and maintenance costs of the units, poses safety hazards to people, livestock, and equipment in the surrounding area, impacts the stable operation of the power grid, and exacerbates the contradiction between power consumption and power generation during the freezing period.

[0003] Air-thermal de-icing is a relatively mature method for de-icing wind turbine blades. It can be used for retrofitting existing wind turbines and adding new turbines. It has a long service life, is easy to maintain, does not attract lightning, and also has a certain degree of anti-icing capability. The principle of air-thermal de-icing is as follows: the inside of the blade is a closed cavity. A blower and heater are installed inside the blade cavity. The heater heats the cold air inside the blade, and the blower sends the heated air out, circulating it along a pre-designed airflow channel within the blade. The hot air heats the inner surface of the blade, and the heat is then conducted from the inner surface to the outer surface. When the temperature of the outer surface of the blade exceeds zero degrees Celsius, the anti-icing and de-icing effects are achieved. In specific designs, such as... Figure 1 , Figure 2 As shown, heater 1 and blower 2 are installed in the manhole baffle at the blade root 14. The air outlet of heater 1 sends hot air to a point about one-third of the blade length away from the blade root through air duct 3. Because the space of the blade leading edge cavity 7 further forward is too small to construct the air duct 3, baffle 4 is installed here to block the hot air flowing out of air duct 3 from flowing back. The hot air can only move from the blade leading edge cavity 7 towards the blade tip 5, and then flow back into the air inlet of blower 2 through the process hole set at the blade tip 5, through the web cavity 6 and the blade trailing edge cavity 11 to form a hot air circulation channel.

[0004] When blades become icy, the icing alters their shape, disrupts their original lifting structure, and drastically reduces their wind-catching capacity. Furthermore, icing increases blade weight and wind resistance, making it difficult for the blades to reach their theoretical rotational speed, resulting in a sharp decline in wind turbine power generation capacity and even shutdown. The part most affected by the lifting structure is the leading edge 10 of the windward blade, because the moment of inertia of icing is greater closer to the blade tip, and the greater the impact on the blade. Therefore, de-icing must begin with removing the ice from the leading edge 10, with priority given to de-icing the area closer to the blade tip 5. To achieve better air-thermal de-icing and reduce self-consumption of electricity, the design needs to prioritize the use of heat from heater 1 on the blade leading edge cavity 7 near the blade tip 5. Therefore, the air-thermal de-icing system uses duct 3 to deliver hot air to the blade tip 5 along the blade web 9 of the blade leading edge cavity 7. However: First, because the cross-sectional area of ​​the blade leading edge cavity 7 decreases closer to the blade tip 5, workers often cannot advance beyond one-third of the blade length from the blade root (at baffle 4) when working on existing fan blades, so duct 3 can only be placed there. Second, the heat from heater 1 to the blade tip 5 decreases as it moves forward. The less heat is used, the lower the temperature, and the worse the de-icing effect, which is the opposite of what is needed. Third, some blade tips are blocked, and hot air cannot flow from the blade tip process hole to the blade trailing edge cavity 11 and the web cavity 6 between the two webs. In other words, a hot air circulation channel cannot be formed, and the hot air cannot circulate. As a result, the heat from the heater 1 cannot be delivered, and the de-icing function fails. Currently, the method to repair blades with blocked blade tips is to open a skylight at the blade tip 5, forcibly drill a hole with a drilling machine to form a hot air circulation channel, and then seal the skylight. This method is not only time-consuming and labor-intensive, but blade manufacturers and owners are also worried that this method will damage the blades due to the immature skylight opening technology. Summary of the Invention

[0005] One of the technical problems to be solved by this invention is that, in the existing wind turbine blade air-thermal de-icing system, the air duct cannot deliver hot air to the area near the blade tip. This invention provides a wind turbine blade air-thermal de-icing system with a flexible air duct that can extend the air duct to the blade tip to enhance the de-icing effect at the blade tip, as well as a method for fixing and disassembling the flexible air duct.

[0006] The second technical problem to be solved by this invention is that, for blades with blocked blade tips, this invention provides a wind turbine blade air-heat de-icing system with flexible duct that can form a new hot airflow circulation channel in the blade leading edge cavity to solve the problem of interruption of the hot airflow circulation channel after blade tip blockage. The system also includes a method for fixing and disassembling the flexible duct.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A fan blade hot-air de-icing system with a flexible duct includes a heater and a blower. The air inlet of the heater is connected to the air outlet of the blower, and the air outlet of the heater is connected to the air inlet of the duct. Hot air blown from the air outlet of the duct is connected to the air inlet of the blower via a hot air return channel. Its structural features are as follows:

[0009] The front end of the air duct is a rigid air duct, and the rear end of the air duct is a flexible air duct. The air inlet of the rigid air duct is connected to the air outlet of the heater, and the air outlet of the rigid air duct is connected to the air inlet of the flexible air duct.

[0010] The blade's inner cavity is divided by the blade web into a blade leading edge cavity facing the windward side of the blade and a blade trailing edge cavity facing the leeward side of the blade. The flexible air duct is arranged in the blade leading edge cavity and extends to near the blade tip. Several air guide holes are opened on the side of the flexible air duct facing the windward side of the blade.

[0011] A hook is installed at intervals along the longitudinal axis of the blade web inside the leading edge cavity of the blade. Multiple fixing ropes are provided on the side of the flexible air duct facing the leeward side of the blade corresponding to the hooks. The flexible air duct is fixed to the blade web by being threaded into the opening of the hook through the fixing ropes.

[0012] Preferably, a flexible duct telescopic structure is provided at the interface between the flexible duct and the rigid duct. The flexible duct telescopic structure includes a fixed end and a movable end arranged sequentially along the blade length direction, and the distance between the fixed end and the movable end is equal to the opening depth of the hook. The fixed end and the movable end are detachably connected.

[0013] Preferably, the opening of the hook faces the blade tip, the fixing rope is installed parallel to the cross-section of the flexible duct, and the fixing end is arranged closer to the blade root than the moving end.

[0014] Preferably, the opening depth of the hook is 15-60mm.

[0015] Preferably, the curvature of the fixing rope is 25°–40°, and the length of the fixing rope is greater than the corresponding arc length of the outer wall of the flexible air duct.

[0016] Preferably, three sets of flexible duct telescopic structures are arranged around the flexible duct.

[0017] Preferably, one or more auxiliary fixing ropes are arranged in front of and behind the fixing rope, the auxiliary fixing ropes are arranged parallel to the fixing rope, and the spacing between any two of the auxiliary fixing ropes and the fixing ropes is less than the opening depth of the hook.

[0018] Preferably, the spacing of the hooks on the blade web is 1500mm-2500mm.

[0019] Preferably, the size and density of the air guide holes on the flexible air duct are determined based on the heat required for de-icing at that location. Generally, the diameter and density of the air guide holes on the flexible air duct are larger the closer they are to the blade tip.

[0020] Preferably, the cross-sectional area of ​​the flexible duct is smaller closer to the blade tip to maintain sufficient air pressure and drive the hot airflow toward the blade tip.

[0021] Preferably, the rigid air duct is installed on the blade web, and a baffle is installed between the blade web and the leading edge of the blade, with the air outlet of the rigid air duct passing through the baffle.

[0022] Preferably, when the blade tip is blocked, multiple hot air return holes are opened on the baffle to form a new hot air return channel between the blade web and the blade leading edge.

[0023] Preferably, the connection between the flexible duct and the rigid duct is fixed with a clamp.

[0024] Preferably, the flexible air duct is a distribution duct.

[0025] Based on the same inventive concept, the present invention also provides a method for fixing the flexible air duct of the wind turbine blade air-heat de-icing system, which includes the following steps:

[0026] 1) When the corresponding blade is in a horizontal or downward position, turn on the blower to straighten the flexible air tube so that the flexible air tube is close to the blade web and the fixing rope on the flexible air tube is close to the hook on the blade web.

[0027] 2) Release the movable end of the flexible duct telescopic structure so that the flexible duct extends under the action of wind force, and the fixing ropes on the flexible duct reach the opening of the corresponding hook on the blade web.

[0028] 3) Retract the moving end of the flexible duct telescopic structure so that each fixing rope on the flexible duct is put into the opening of the corresponding hook on the blade web, thus completing the fixing of the flexible duct.

[0029] Based on the same inventive concept, the present invention also provides a method for disassembling the flexible air duct of the wind turbine blade air-heat de-icing system, which includes the following steps:

[0030] 1) When the corresponding blades are in the horizontal or downward position, turn on the blower to straighten the flexible air duct;

[0031] 2) Release the movable end of the flexible duct telescopic structure so that the flexible duct extends under the action of wind force, and the fixing ropes on the flexible duct just disengage from the openings of the corresponding hooks on the blade web.

[0032] 3) Turn off the blower, open the fixing clamp between the flexible air duct and the rigid air duct, rotate the flexible air duct 90° to 180°, and then tighten the clamp to fix the flexible air duct.

[0033] 4) Turn the blower on again to straighten the flexible air tube, so that the fixing rope on the flexible air tube is away from the hook on the blade web, and at the same time the flexible air tube is away from the blade web.

[0034] 5) Turn off the blower again and slowly retract the flexible air hose. After the flexible air hose is completely retracted, open the clamp between the flexible air hose and the rigid air hose to remove the flexible air hose.

[0035] The design principle of this invention:

[0036] 1) By utilizing the contraction and expansion characteristics of the flexible air duct, the flexible air duct can be extended to the blade tip position when the air is introduced, thereby automatically delivering hot air to the blade tip;

[0037] 2) Open air guide holes on the flexible air duct as needed (the diameter and density of the air guide holes on the flexible air duct are larger the closer they are to the blade tip). Control the heat distribution along the flexible air duct during heating through the air guide holes, so as to heat the leading edge of the blade as needed, that is, to distribute the total heat according to the heat required for de-icing the leading edge of the blade.

[0038] 3) Deliver the most heat to the blade tip (the diameter and density of the air guide holes closer to the blade tip on the flexible air duct are larger) to remove the ice buildup on the blade tip first.

[0039] 4) Because there is a continuous loss of air volume along the way in the flexible air duct, in order to maintain sufficient air pressure and push the hot airflow toward the blade tip, the cross-sectional area of ​​the flexible air duct is smaller as it gets closer to the blade tip.

[0040] 5) For blades with clogged tips, the hot air blown out by the flexible duct can flow back to the blade root through the hot air return holes on the blade leading edge cavity and baffle outside the flexible duct. It is then drawn in by the blower, blown into the heater, reheated, and then blown back to the blade tip through the duct, forming a new, stable circulating airflow. See [link to relevant documentation]. Figure 3 .

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] 1) The present invention adds a flexible air duct design at the outlet of the last rigid air duct and uses hot air to extend it to the blade tip. This not only extends the air transport channel and solves the construction problem of extending the air duct inside the blade, but also allows the hot air to reach the blade tip first, ensuring the de-icing effect of the blade tip and enabling the hot air resources to be accurately distributed to the blade de-icing position required.

[0043] 2) The flexible air duct of the present invention has an air guide hole at the position facing the leading edge of the blade, which guides the hot air directly to the leading edge of the blade, which not only improves the heat utilization efficiency, but also improves the de-icing speed and de-icing capacity of the leading edge of the blade.

[0044] 3) Along the length of the flexible air duct of this invention, the diameter and number of air guide holes are designed according to the heat required for de-icing at different blade leading edges. The closer to the blade tip, the higher the priority (the larger the diameter and density of the air guide holes are at the blade tip). This allows the total heat of the de-icing system to be scientifically distributed, ensuring sufficient heat at the blade tip position that needs de-icing the most. This not only results in a better de-icing effect but also significantly improves heat utilization efficiency and reduces the total power of the heater and the overall self-consumption of the de-icing system.

[0045] 4) The cross-sectional area of ​​the flexible air duct of the present invention is smaller closer to the blade tip, so that although there are air guide holes along the way and there is always air volume loss, it can still maintain sufficient air pressure to push the hot airflow toward the blade tip.

[0046] 5) When the blade tip is blocked and the hot air return duct required for normal de-icing cannot be formed, this invention reconstructs a new hot air circulation duct by constructing a hot air return duct in the leading edge cavity of the blade outside the flexible air duct. This solves the problem of blade tip blockage preventing the achievement of gas-heat de-icing. Moreover, the newly constructed hot air circulation duct allows hot air to return from the outlet of the flexible air duct near the blade tip. The closer to the blade tip, the higher the temperature and the more heat, which fully conforms to the principle that the heat for de-icing is given higher priority closer to the blade tip, resulting in better de-icing effect.

[0047] 6) When the blade tip is blocked and a normal hot air return duct for de-icing cannot be formed, the present invention achieves this by opening hot air return holes on the baffle when constructing a new hot air return duct in the leading edge cavity of the outer blade of the flexible air duct. By maximizing the total cross-sectional area of ​​the hot air return holes, the hot air return resistance can be reduced, thereby improving the de-icing performance of the system. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the installation structure of an existing wind turbine blade internal air-heat de-icing system.

[0050] Figure 2 This is a schematic diagram of the blades being covered in ice.

[0051] Figure 3 This is a schematic diagram of the structure of the present invention.

[0052] Figure 4 This is a schematic diagram of the connection between flexible and rigid air ducts.

[0053] Figure 5 This is a schematic diagram showing the length of the flexible air duct when the blade tip is not blocked.

[0054] Figure 6 This is a diagram showing the distribution of air guide holes on a flexible air duct.

[0055] Figure 7 This is a schematic diagram of the hook structure installed on the blade web.

[0056] Figure 8 This is a schematic diagram showing the installation position of the hook on the blade web.

[0057] Figure 9 Diagram showing the installation structure of the fixing rope on the flexible duct (relative to the cross-section of the flexible duct).

[0058] Figure 10 This is a schematic diagram showing the installation position of the fixing rope on the flexible air duct.

[0059] Figure 11 This is a schematic diagram showing the arrangement of the flexible duct telescopic structure around the flexible duct.

[0060] Figure 12 This is a diagram showing the deployment status of the mobile end of the flexible duct telescopic structure.

[0061] Figure 13 This diagram shows the connection state between the moving end and the fixed end of the flexible duct telescopic structure.

[0062] Figure 14 A schematic diagram showing the location of auxiliary fixing ropes on flexible air ducts.

[0063] Figure 15 This is a schematic diagram of the structure of the present invention when the blade tip is blocked.

[0064] Figure 16 This is a schematic diagram showing the length of the flexible air duct when the blade tip is blocked.

[0065] Figure 17 This is a front view of the baffle structure.

[0066] Figure 18 This is a diagram showing the temperature changes of each blade half an hour after the de-icing system has been turned on.

[0067] Figure 19 This is a diagram showing the temperature changes of each blade two hours after the de-icing system was turned on.

[0068] In the diagram: 1. Heater; 2. Blower; 3. Air duct; 4. Baffle; 5. Blade tip; 6. Web cavity; 7. Blade leading edge cavity; 8. Blade tip blockage; 9. Blade web; 10. Blade leading edge; 11. Blade trailing edge cavity; 12. Clamp; 13. Hot air return channel; 14. Blade root; 15. Hook; 16. Fixing rope; 17. Flexible air duct telescopic structure; 18. Auxiliary fixing rope; 31. Rigid air duct; 32. Flexible air duct; 41. Hot air return hole; 42. Rigid air duct perforation; 171. Fixed end; 172. Moving end; 311. Rigid air duct outlet; 321. Air guide hole; 322. Flexible air duct inlet. Detailed Implementation

[0069] The present invention will be further described below with reference to specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0070] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0071] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0072] Please see Figures 3-6 The first embodiment of the wind turbine blade air-heat de-icing system of the present invention includes a heater 1 and a blower 2 installed in the manhole baffle at the root 14 of the blade. The air inlet of the heater 1 is connected to the air outlet of the blower 2, and the air outlet of the heater 1 is connected to the air inlet of the air guide pipe 3. The air outlet of the air guide pipe 3 points towards the blade tip 5. The hot air delivered by the air guide pipe 3 blows towards the blade tip and then enters the air inlet of the blower 2 through the hot air return channel 13.

[0073] The front end of the air duct 3 adopts a conventional rigid air duct 31, and the rear end of the air duct 3 adopts a flexible air duct 32. The air inlet of the rigid air duct 31 is connected to the air outlet of the heater 1, and the air outlet of the rigid air duct 31 is connected to the air inlet of the flexible air duct 32. The flexible air duct 32 is arranged in the blade leading edge cavity 7 and extends to near the blade tip 5. Several air guide holes 321 are opened on the flexible air duct 32 at the position facing the blade leading edge 10 (i.e. the side of the blade facing the windward side of the blade), so that the hot air blows towards the blade leading edge 10 and the blade tip 5, and then enters the web cavity 6 and the blade trailing edge cavity 11 through the process hole of the blade tip 5, and finally flows into the air inlet of the blower 2 located at the blade root 14 to form a hot air circulation channel.

[0074] The rigid air duct 31 is installed on the blade web 9, and a baffle 4 is installed between the blade web 9 and the blade leading edge 10, with the air outlet of the rigid air duct 31 passing through the baffle 4.

[0075] like Figure 7 - Figure 14 As shown, hooks 15 are installed at intervals along the blade length at the middle position of the blade web 9 within the blade leading edge cavity 7, with the openings of the hooks 15 facing the blade tip 5. Several fixing ropes 16 are designed on the flexible duct 32 at the contact points with the blade web 9. Each fixing rope 16 is installed parallel to the cross-section of the flexible duct 32, and the spacing between adjacent fixing ropes 16 is equal to the spacing between adjacent hooks 15. The flexible duct 32 is fixed to the blade web 9 by the fixing ropes 16 being inserted into the openings of the hooks 15.

[0076] At the interface between the flexible duct 32 and the rigid duct 31, three sets of flexible duct telescopic structures 17 are arranged around the flexible duct 32. Each flexible duct telescopic structure 17 includes a fixed end 171 and a movable end 172 arranged along the longitudinal axis of the blade web 9. The distance between the fixed end 171 and the movable end 172 is equal to the opening depth of the hook 15, and the fixed end 171 and the movable end 172 are detachably connected. In this embodiment, the opening depth of the hook 15 is 30 mm.

[0077] In a specific implementation of the first embodiment of the wind turbine blade air-heat de-icing system of the present invention:

[0078] 1. At the location where the baffle 4 is installed inside the leading edge cavity 7 of the blade, or at the outlet of the last rigid duct section 31, the flexible duct 32, such as a distribution duct, is fixed by clamp 12. Figure 4 ;

[0079] 2. The length S2 of the flexible duct is taken as a reference from the distance S from the outlet of the last rigid duct section to the blade tip, minus the blade length S1 that the flexible duct 32 cannot pass through because the cross-sectional area of ​​the blade leading edge cavity 7 is smaller closer to the blade tip 5. That is, the length S2 of the flexible duct is S2 = S - S1. See Figure 5 ;

[0080] 3. Air guide holes 321 are opened on the flexible air duct 32 at positions facing the leading edge 10 of the blade, as needed. The size and density of the air guide holes 321 are determined based on the heat required for de-icing the corresponding leading edge 10 of the blade. The general principle is that the closer to the blade tip 5, the higher the priority; that is, the larger the diameter and density of the air guide holes 321 are, the closer to the blade tip 5. (See...) Figure 6 ;

[0081] 4. The cross-sectional area of ​​the flexible air duct 32 is smaller as it gets closer to the blade tip, in order to maintain sufficient air pressure and drive the hot airflow toward the blade tip 5.

[0082] 5. Hook 15 design: such as Figure 7 The material is selected from soft materials such as plastic, so that the hook 15 and the blade web 9 can deform synchronously without being damaged; the material strength of the hook 15 must be guaranteed to prevent breakage during long-term use; the total thickness H of the hook 15 needs to be controlled within 10mm to ensure that the flexible air duct 32 will not be deformed too much during use, thus increasing wind resistance; the opening depth L of the hook 15 is the same as the extension length of the flexible air duct extension structure 17, which is 30mm.

[0083] 6. The hook 15 can be fixed in a variety of ways: for example, double-sided tape can be pasted on the fixing surface of the hook 15 and pasted to a predetermined position on the blade web 9 by means of double-sided tape, or it can be integrally formed with the blade web 9 during the manufacturing process.

[0084] 7. The first hook 15 is fixed at the middle of the blade web 9, with the opening of hook 15 2m away from the outlet of the rigid duct 31. Subsequent hooks 15 are fixed at intervals of 2m. See below. Figure 8 ;

[0085] 8. The fixing rope 16 on the flexible air duct 32 is fixed parallel to the cross-section of the flexible air duct 32 and installed on the outer wall of the flexible air duct 32 on the back of the air guide hole 321, with an arc of 30° and a length slightly longer than the corresponding arc length of the outer wall of the flexible air duct 32, so as to facilitate the insertion of the hook 15. See Figure 9 ;

[0086] 9. The first fixing rope 16 is positioned on the flexible air duct 32 at a point 2m + 1cm from the interface between the flexible air duct 32 and the rigid air duct 31 towards the blade tip. Subsequent ropes are installed every 2m. See [reference needed]. Figure 10 ;

[0087] 10. Design of Flexible Duct Extension Structure 17: At the position where the flexible duct 32 fits into the rigid duct 31, three sets of flexible duct extension structures 17 are arranged around the flexible duct 32, see... Figure 11Each flexible duct telescopic structure 17 includes a fixed end 171 and a movable end 172 arranged 30mm apart along the blade length direction, and the distance between the fixed end 171 and the movable end 172 is equal to the opening depth of the hook 15. The fixed end 171 and the movable end 172 are detachably connected. When the flexible duct 32 needs to be extended, the movable end 172 is released. Figure 12 When the flexible duct 32 needs to be shortened, the fixed end 171 and the movable end 172 should be tightly bound together, see [link / reference]. Figure 13 ;

[0088] 11. To eliminate process errors and improve the success rate of inserting the fixing rope 16, one or more auxiliary fixing ropes 18 are added before and after each fixing rope 16. The auxiliary fixing ropes 18 are arranged parallel to the fixing ropes 16. The spacing between any two of the auxiliary fixing ropes 18 and the fixing ropes 16 in the sequence is less than the opening depth of the hook 15, which is 25mm. Figure 14 .

[0089] The specific method for fixing the flexible air duct 32 in the first embodiment of the air-heat de-icing system for wind turbine blades of the present invention is as follows:

[0090] 1. When the corresponding blade is in a horizontal or downward position, turn on the blower 2 to straighten the flexible air pipe 32. Because the flexible air pipe 32 has air guide holes 321 arranged on the side facing the leading edge of the blade, the reaction force of the air guide will make the flexible air pipe 32 stick to the blade web 9, and the fixing rope 16 on the flexible air pipe 32 and the hook 15 on the blade web 9 will be close together.

[0091] 2. Release the movable end 172 of the flexible duct telescopic structure 17 so that the flexible duct 32 extends under the action of wind force, and the fixing ropes 16 on the flexible duct 32 reach the opening of the corresponding hook 15 on the blade web 9.

[0092] 3. Retract the movable end 172 of the flexible duct telescopic structure 17, and then put each fixing rope 16 on the flexible duct 32 into the opening of the corresponding hook 15 on the blade web 9, and make sure it does not come out, thus completing the fixing of the flexible duct 32.

[0093] When the flexible air duct 32 in the first embodiment of the wind turbine blade air-thermal de-icing system of the present invention needs to be repaired or replaced, the old flexible air duct 32 can be removed. The specific method is as follows:

[0094] 1. When the corresponding blades are in the horizontal or downward position, turn on the blower 2 to straighten the flexible air duct 32;

[0095] 2. Release the movable end 172 of the flexible duct telescopic structure 17 so that the flexible duct 32 extends under the action of wind force, and the fixing ropes 16 on the flexible duct 32 are just disengaged from the openings of the corresponding hooks 15 on the blade web 9.

[0096] 3. Turn off blower 2, open the fixing clamp 12 between flexible air duct 32 and rigid air duct 31, rotate flexible air duct 32 90°~180°, and then tighten clamp 12 to fix flexible air duct 32.

[0097] 4. Turn on the blower 2 again to straighten the flexible air tube 32. At this time, due to the air guiding effect of the air guide hole 321, the fixing rope 16 on the flexible air tube 32 will move away from the hook 15 on the blade web 9. At the same time, the flexible air tube 32 will also deviate to one side and move away from the blade web 9.

[0098] 5. Turn off blower 2 again and slowly retract flexible air duct 32. After flexible air duct 32 is completely retracted, open clamp 12 between flexible air duct 32 and rigid air duct 31 to remove flexible air duct 32.

[0099] Please see Figures 15-17 The second embodiment of the wind turbine blade hot air de-icing system of the present invention is largely the same as the first embodiment, except that the tip of the wind turbine blade is blocked 8, and multiple hot air return holes 41 are opened on the baffle 4. After the hot air is blown out of the flexible air duct 32, it is blocked by the tip blockage 8 and cannot reach the web cavity 6 and the trailing edge cavity 11 of the blade. Instead, it can only return through the new hot air return channel 13 formed by the hot air return holes 41 on the outer periphery of the flexible air duct 32 in the leading edge cavity 7 of the blade and enter the air inlet of the blower 2 located at the root of the blade 14 to form a new hot air circulation channel.

[0100] Due to the blade tip blockage 8, and considering the cross-sectional area of ​​the hot air return channel 13, the length S2' of the flexible duct is determined by subtracting the blade length S1 (because the cross-sectional area of ​​the blade leading edge cavity 7 decreases closer to the blade tip blockage 8, preventing the flexible duct 32 from passing through) and the shortened flexible duct length S1' (to ensure the cross-sectional area of ​​the hot air return channel 13). This results in the blade leading edge cavity cross-sectional area at the flexible duct outlet = flexible duct cross-sectional area + newly formed hot air return channel 13 cross-sectional area. Therefore, the flexible duct length S2' = S - S1 - S1'. (See...) Figure 16 Multiple hot air return holes 41 are provided on the baffle 4 (e.g., Figure 17 This creates a new hot air return channel 13 around the outer periphery of the air guide duct 3 within the leading edge cavity 7 between the blade web 9 and the blade leading edge 10 (see...). Figure 3 (As indicated by the arrow pointing to the right).

[0101] The external temperature changes of the first blade (with a flexible duct) and the second and third blades (without a flexible duct) were recorded using a drone and infrared cameras. Figure 18 , Figure 19 The experimental results shown include, Figure 18 This is a graph showing the temperature changes of each blade half an hour after the de-icing system has been turned on. Figure 19This is a diagram showing the temperature changes of each blade two hours after the de-icing system was turned on.

[0102] Depend on Figure 18 It can be seen that the second and third blades have a higher concentration of heat at the rigid duct outlet. However, due to the installation of a flexible duct (distributor duct) on the first blade, some of the heat that should have been concentrated at the rigid duct outlet is transported to the middle and tip of the blade. Furthermore, because the flexible duct (distributor duct) has a guide hole 321 facing the leading edge 10 of the blade, the heat is primarily used to heat the leading edge 10. Therefore, the temperature after the rigid duct outlet of the first blade rises rapidly, significantly higher than the corresponding temperatures on the second and third blades, and the temperature distribution is more uniform. Since the second blade is fixed upwards, it has a larger area exposed to sunlight, resulting in a higher temperature compared to the third blade.

[0103] Depend on Figure 19 It can be seen that as the de-icing system is operated for longer periods, the surface temperature of all three blades increases. However, the temperature distribution of the first blade is more even and less volatile than that of the second and third blades. The peak temperature of the first blade is 35.6℃, the trough temperature is 31.0℃, and the temperature difference is 4.6℃; the peak temperature of the second blade is 39.7℃, the trough temperature is 31.8℃, and the temperature difference is 7.9℃; the peak temperature of the third blade is 41.2℃, the trough temperature is 26.6℃, and the temperature difference is 14.6℃. It can be seen that the first blade has the smallest temperature difference and the most uniform heat distribution after the air distribution duct is installed, which is beneficial to further improving the energy efficiency ratio of the de-icing system.

[0104] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention, or modify it into equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. A wind turbine blade hot air de-icing system with a soft duct, comprising a heater and a blower, an air inlet of the heater being connected with an air outlet of the blower, an air outlet of the heater being communicated with an air inlet of a duct, and hot air blown out of the air outlet of the duct being communicated with the air inlet of the blower, characterized in that: a front end of the duct is a hard duct, a rear end of the duct is a soft duct, the air inlet of the hard duct is communicated with the air outlet of the heater, and the air outlet of the hard duct is communicated with the air inlet of the soft duct; an inner cavity of the blade is divided into a blade leading edge cavity facing a windward side of the blade and a blade trailing edge cavity facing a leeward side of the blade by a blade web, the soft duct is arranged in the blade leading edge cavity and extends to near a blade tip, and a plurality of air guide holes are formed in a side of the soft duct facing the windward side of the blade; a longitudinal axis of the blade web in the blade leading edge cavity is provided with a hook at every certain distance, a plurality of fixing ropes are arranged on a side of the soft duct facing the leeward side of the blade corresponding to the hooks, and the soft duct is fixed on the blade web by being sleeved into the opening of the hook through the fixing ropes; a soft duct telescopic structure is arranged at an interface between the soft duct and the hard duct, the soft duct telescopic structure comprises a fixed end and a moving end arranged in sequence along a length direction of the blade, a distance between the fixed end and the moving end is equal to an opening depth of the hook, and the fixed end and the moving end are detachably connected; the opening of the hook faces the blade tip, the fixing ropes are arranged in parallel to a cross section of the soft duct, and the fixed end is arranged closer to a blade root relative to the moving end. The opening depth of the hook is 15-60 mm. Three groups of the soft duct telescopic structure are arranged around the soft duct. One or more auxiliary fixing ropes are arranged in front of and behind the fixing ropes respectively, the auxiliary fixing ropes are arranged in parallel to the fixing ropes, and a distance between two of the auxiliary fixing ropes and the fixing ropes in sequence is less than the opening depth of the hook. The distance between the hooks on the blade web is 1500-2500 mm. The method comprises the following steps:

2. The fan blade pneumatic thermal de-icing system with flexible hoses of claim 1, wherein, 1) turning on the blower when the corresponding blade is in a horizontal or downward position, blowing the soft duct straight, and making the soft duct adhere to the blade web and the fixing ropes on the soft duct close to the hooks on the blade web; 3. The fan blade pneumatic thermal de-icing system with flexible hoses of claim 1, wherein, The arc of the fixed rope is 25 o - 40 o , and the length of the fixed rope is greater than the corresponding arc length of the outer wall of the flexible duct.

4. The fan blade pneumatic thermal de-icing system with flexible hoses of claim 1, wherein, 2) releasing the moving end of the soft duct telescopic structure, making the soft duct elongate under the action of wind, and making each fixing rope on the soft duct reach the opening of the corresponding hook on the blade web; 5. The fan blade pneumatic thermal de-icing system with flexible hoses of claim 1, wherein, 3) retracting the moving end of the soft duct telescopic structure, and making each fixing rope on the soft duct be sleeved into the opening of the corresponding hook on the blade web, i.e. completing the fixation of the soft duct.

6. The fan blade pneumatic thermal de-icing system with flexible hoses of claim 1, wherein, The method comprises the following steps:

7. A method of securing a flexible duct of a fan blade pneumatic thermal de-icing system according to any one of claims 1 to 6, wherein 1) turning on the blower when the corresponding blade is in a horizontal or downward position, and blowing the soft duct straight; 2) releasing the moving end of the soft duct telescopic structure, making the soft duct elongate under the action of wind, and making each fixing rope on the soft duct be separated from the opening of the corresponding hook on the blade web; 4) turning on the blower again, blowing the soft duct straight, making the fixing ropes on the soft duct be separated from the hooks on the blade web, and making the soft duct be separated from the blade web. ​ 8. A method of removing the flexible duct of the fan blade pneumatic thermal de-icing system according to any one of claims 1 to 6, characterized in that ​ ​ ​ 3) Turn off the blower, open the fixed clamp between the soft wind pipe and the hard wind pipe, rotate the soft wind pipe 90 o ~180 o , lock the clamp again, fix the soft wind pipe; ​ 5) Close the blower again, slowly retract the flexible duct, open the clamp between the flexible duct and the rigid duct after the flexible duct is completely retracted, and then remove the flexible duct.

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