Wind turbine blade manufacturing

Abstract

A wind turbine blade is disclosed. A wind turbine blade includes a core material, a first fiber reinforced plastic, a shear web including a second fiber reinforced plastic, and an adhesive. The shear web is adhered to the blade shell by an adhesive, and the first fiber reinforced plastic, the second fiber reinforced plastic and the adhesive each comprise an acid cleavable epoxy polymer. Also disclosed is a method of decomposing such a wind turbine blade by exposing the wind turbine blade to an acid to disintegrate the acid cleavable epoxy polymer into swollen epoxy polymer particles; and recovering fibers from the first fiber-reinforced plastic and / or the second fiber-reinforced plastic.

Description

Technical Field

[0001] The present invention generally relates to wind turbine blades and methods for reusing wind turbine blades. Background Art

[0002] Composite wind turbine blades consist of multiple components, each constructed to withstand the loads and conditions they experience during long-term use under extreme conditions, while being constrained by space, weight, and shape to achieve an efficient aerodynamic shape. Using composite materials to manufacture such components is generally advantageous because the arrangement of materials used can be highly optimized to the specific requirements of each component. However, this can result in a very complex bill of materials for the blade, including multiple types of fiber-reinforced plastics, foam core materials, and resin systems, and can limit overall reuse strategies because each component may require different treatment at end-of-life for full reuse.

[0003] Furthermore, the structural properties of composite wind turbine blades make it difficult to separate components and materials mechanically or chemically once the bonding resins and adhesives cure. This makes it challenging to extract materials from scrapped blades for reuse.

[0004] The present invention was born in such background. Summary of the Invention

[0005] A first aspect of the present invention provides a wind turbine as claimed in claim 1. The wind turbine blade comprises: a blade shell comprising a core material and a first fiber reinforced plastic; a shear web comprising a second fiber reinforced plastic; and an adhesive. The shear web is bonded to the blade shell by an adhesive, and the first fiber reinforced plastic, the second fiber reinforced plastic and the adhesive each comprise an acid-cleavable epoxy polymer. It has been found that this is very advantageous because it allows multiple components of the wind turbine blade to be disintegrated simultaneously and / or under the same conditions without having to first separate the components from each other. To date, the recycling of wind turbine blades has mainly focused on the recycling of fiber reinforced plastic components, and mainly on the extraction of fibers for reuse. In the present invention, the design of the blade allows both the fiber reinforced plastic components and the polymer components that do not contain reusable fiber reinforcement (adhesive and optionally other polymer components, such as coatings and foams) to be reused using a common strategy, thereby greatly improving the efficiency of the recycling process. In addition, by first disrupting one or more acid-cleavable polymers and then separating the components that do not contain acid-cleavable epoxy polymers from the components that contain acid-cleavable epoxy polymers, it is easier to separate the components that do not contain acid-cleavable epoxy polymers from the components that have been disrupted. In addition, some components that include acid-cleavable epoxy polymers also include non-acid-cleavable elements, such as fibers, sensors, and metal parts, which can also be easily removed after the acid-cleavable epoxy polymers are disrupted into swollen epoxy polymer particles. Epoxy polymers in this article refer to cross-linked or entangled polymer systems formed in whole or in part by the reaction of epoxy groups. Acid-cleavable epoxy polymers in this article refer to epoxy polymers that are capable of swelling and mechanically cleaving some of their chemical bonds when exposed to acid. As a result, objects composed of epoxy polymers will form swollen epoxy polymer particles. The process of swelling the acid-cleavable epoxy polymer into swollen epoxy polymer particles is interchangeably referred to herein as swelling, acid cleavage, or disruption. The acid-cleavable epoxy polymer can be, for example, an epoxy polymer based on an amine-cured epoxy resin, such as Olin Airstone 760, Hexion RIMR 035C infusion epoxy resin, or Aditya Birla Recyclamine system. In other words, epoxy polymers based on amine-cured epoxy resins constitute a subclass of acid-cleavable epoxy polymers. In the wind turbine blade according to the present invention, the acid-cleavable epoxy polymer is preferably an epoxy polymer based on an amine-cured epoxy resin.

[0006] Alternatively, the acid-cleavable epoxy polymer in each of the first fiber-reinforced plastic, the second fiber-reinforced plastic, and the adhesive is acid-cleavable in an acidic fluid comprising acetic acid and / or formic acid. Both formic acid and acetic acid are readily available bulk chemicals, can be sourced from recyclable sources, and have limited chemical risks.

[0007] Optionally, the acid-cleavable epoxy polymers in each of the first fiber-reinforced plastic, the second fiber-reinforced plastic, and the adhesive are all based on amine-cured epoxy resins. Such resins are readily commercially available and have been shown to have relatively rapid acid cleavage, particularly in acidic fluids containing formic acid.

[0008] In an embodiment, the wind turbine blade further comprises a spar and / or a spar cap as a load-bearing component of the wind turbine blade. The structural spar or spar cap may be integrally formed with the blade shell. The spar and / or spar cap comprises a third fiber-reinforced plastic comprising an acid-cleavable epoxy polymer. The spar and / or spar cap may be a pultruded fiber-reinforced plastic. The acid-cleavable epoxy polymer in the third fiber-reinforced plastic preferably has similar chemical properties to the acid-cleavable epoxy polymers in each of the first fiber-reinforced plastic, the second fiber-reinforced plastic, and the adhesive. This enables different parts of the blade to be swollen in the same process, thereby reducing the complexity of the recycling plant. Research has found that if the fibers of the third fiber-reinforced plastic are different from the fibers of the first and / or second fiber-reinforced plastics, it may be advantageous to separate the spar and / or spar cap from the rest of the blade before swelling the third fiber-reinforced plastic, as this allows for the production of fiber portions of a single fiber type, making the reuse of the individual fiber portions easier and more valuable. Alternatively, the acid-cleavable epoxy polymer included in the spar and / or spar cap may be a different acid-cleavable epoxy polymer than the acid-cleavable epoxy polymer of at least the first and second fiber reinforced plastics, wherein the acid-cleavable epoxy polymer of the spar and / or spar cap will decompose under different conditions and / or at different rates under the same conditions to facilitate separation of the spar and / or spar cap, or to facilitate separation of the fibers of the spar and / or spar cap from the fibers of the first and second fiber reinforced plastics.

[0009] In an embodiment, the wind turbine blade further comprises at least one wind turbine blade coating disposed on the blade shell, wherein the blade coating further comprises an acid-cleavable epoxy polymer. Preferably, the acid-cleavable epoxy polymer of the wind turbine blade coating has similar chemical properties to the acid-cleavable epoxy polymers of the first fiber-reinforced plastic, the second fiber-reinforced plastic, and the adhesive. Research has found that this allows for a system in which the coating swells with other components, thereby not delaying or preventing swelling of other blade components. Furthermore, this increases the amount of reusable material in the blade.

[0010] The core material can be a lightweight, dimensionally stable material, such as a balsa wood core material or a polymer foam core material. In an embodiment, the core material is a thermoplastic foam core material and is preferably not a material that is an acid-cleavable epoxy polymer. Therefore, after the components comprising the acid-cleavable epoxy polymer have partially or completely collapsed, the foam core material can be easily separated from these components. The same is true if the core material is based on balsa wood, for example. In another embodiment, the core material is a foam core material and comprises an acid-cleavable epoxy polymer, and preferably, the acid-cleavable epoxy polymer of the foam core material has similar chemical properties to the acid-cleavable epoxy polymers in each of the first fiber-reinforced plastic, the second fiber-reinforced plastic and the adhesive. In this embodiment, the foam core material can swell together with the other components comprising the acid-cleavable epoxy polymer, so that the foam core material does not need to be mechanically separated before swelling.

[0011] In addition to the adhesive, the wind turbine blade may include an additional adhesive. The additional adhesive may also include an acid-cleavable epoxy polymer. Preferably, the acid-cleavable epoxy polymer of the additional adhesive has similar chemical properties to the adhesive. In another embodiment, the additional adhesive has a different chemical property than the adhesive. Preferably, the additional adhesive disintegrates much faster or much slower than the adhesive.

[0012] A wind turbine blade may include a putty, also known as a filler, for adjusting the aerodynamic shape of the wind turbine blade and filling gaps. The putty may include an acid-cleavable epoxy polymer, and preferably, the acid-cleavable epoxy polymer in the putty has similar chemical properties to the acid-cleavable epoxy polymers in each of the first fiber-reinforced plastic, the second fiber-reinforced plastic, and the adhesive. In this embodiment, the putty is swellable along with other components including the acid-cleavable epoxy polymer, thus eliminating the need for mechanical separation of the components prior to swelling.

[0013] In an embodiment, the properties of the first component differ from the properties of the second component, wherein the first component and the second component are different components selected from the group consisting of a first fiber-reinforced plastic, a second fiber-reinforced plastic, and an adhesive. If one or more of the spar and / or spar cap, the coating, the core material, the third fiber-reinforced plastic, and the additional adhesive comprises an acid-cleavable epoxy polymer, then the group preferably also comprises an acid-cleavable epoxy polymer comprising the listed component. Preferably, the different properties are at least two properties selected from tensile strength, compressive strength, flexural strength, hardness, Young's modulus, transparency, abrasion resistance, surface gloss, and density. For example, for the first and second fiber-reinforced plastics, the acid-cleavable epoxy polymers are preferably transparent to facilitate visual inspection of wetting and / or the presence of porosity in the cured fiber-reinforced plastics, in contrast to the adhesive and the additional adhesive, which are preferably opaque, more preferably dyed a bright color (such as green, blue, red, or yellow) to facilitate visual inspection of the presence of adhesive in critical locations. For the core material, its density is preferably significantly lower than that of the other components, and typically the core material has a density less than 50% of that of the other components, for example due to the incorporation of small, lightweight particles or air bubbles into the core material. The coating preferably has higher wear resistance measured in an accelerated rain erosion test than other components, and / or higher surface gloss than other components.

[0014] In an embodiment, the acid-cleavable epoxy polymer of the first component has different properties than the acid-cleavable epoxy polymer of the second component, wherein the first component and the second component are different components selected from the group consisting of a first fiber-reinforced plastic, a second fiber-reinforced plastic, and an adhesive. If one or more of the spar and / or spar cap, the coating, the core material, the third fiber-reinforced plastic, and the additional adhesive comprises an acid-cleavable epoxy polymer, then the group preferably also includes an acid-cleavable epoxy polymer comprising the listed component. The different properties are preferably at least two properties selected from glass transition temperature, tensile strength, compressive strength, flexural strength, hardness, Young's modulus, transparency, and density. Generally, the glass transition temperature is preferably above 70°C, but for coatings, the glass transition temperature is preferably higher, such as above 80°C or above 90°C. For both the first and second fiber-reinforced plastics, the acid-cleavable epoxy polymer is preferably transparent to facilitate visual inspection of wettability and the absence of pores in the cured fiber-reinforced plastics. As for the adhesive and additional adhesive, they are preferably opaque, more preferably dyed in a bright color (such as green, blue, red or yellow) to facilitate visual inspection of the presence of adhesive in critical locations. As for the core material, it is preferred that the acid-cleavable epoxy polymer has higher compressive strength and shear strength than other components.

[0015] In another embodiment, the properties of the uncured acid-cleavable epoxy polymer resin of the first component differ from the properties of the uncured acid-cleavable epoxy polymer of the second component, wherein the first component and the second component are different components selected from the group consisting of a first fiber-reinforced plastic, a second fiber-reinforced plastic, and an adhesive. If one or more of the spar and / or spar cap, coating, core material, third fiber-reinforced plastic, and additional adhesive comprises an acid-cleavable epoxy polymer, then preferably the group also comprises an acid-cleavable epoxy polymer comprising the listed components. Preferably, the different properties are at least two properties selected from transparency, color, viscosity, pot life, and cure time. The uncured acid-cleavable epoxy polymer resins of the first fiber-reinforced plastic and the second fiber-reinforced plastic preferably have a longer pot life and lower viscosity to allow for complete impregnation before the resin cures. The adhesive and additional adhesive (if any) are preferably opaque, more preferably dyed a bright color (such as green, blue, red, or yellow) to allow visual inspection of the presence of adhesive in critical locations before the resin cures. The acid-cleavable epoxy polymer resin (if any) in the foam material preferably has a higher bubble holding capacity (e.g., high viscosity and surface energy), a shorter cure time, and a lower cure temperature. The acid cleavable epoxy polymer resin in the spar and / or spar cap, if any, is preferably provided via pultrusion of glass or carbon fibres, with rapid curing preferably to enable rapid processing.

[0016] In another embodiment, the acid-cleavable epoxy polymers in each of the first fiber-reinforced plastic, the second fiber-reinforced plastic, and the adhesive are acid-cleavable or swellable under the same process conditions. The process conditions can be one or more of temperature, time, pressure, the fluid used in the process, the concentration of substances in the fluid, the presence of active ingredients (such as catalysts in the fluid), etc. This allows the acid-cleavable epoxy polymers of these components to swell simultaneously, and then the other parts of these components, such as fibers, metal inserts, sensors and other polymer components, can be easily separated after or during the swelling process.

[0017] In another embodiment, the acid-cleavable epoxy polymer of the first component and the acid-cleavable epoxy polymer of the second component are swellable under a first set of process conditions, wherein the acid-cleavable epoxy polymer of the first component swells faster under the first set of process conditions than the acid-cleavable epoxy polymer of the second component swells under the first set of process conditions. This allows for sequential decomposition of the wind turbine blade. For example, the second component may comprise carbon fibers and the first component may comprise glass fibers, such that the gradual swelling of the polymers can separate the glass fibers before the component comprising carbon fibers is fully swollen, thereby producing two separate fiber components—one comprising solely or primarily glass fibers and the other comprising solely or primarily carbon fibers. Such separated components can be reused in higher-value applications compared to a mixture comprising significant amounts of both glass and carbon fibers.

[0018] Optionally, the wind turbine blade further comprises a leading edge protector disposed on at least a portion of the blade leading edge, wherein at least a portion of the leading edge protector and / or a leading edge adhesive adhering the leading edge protector to the blade comprises an acid-cleavable epoxy polymer.

[0019] A second aspect of the invention provides a method of breaking down a wind turbine blade or fragments of a wind turbine blade according to claim 11 .

[0020] A second aspect of the present invention provides a method for decomposing a wind turbine blade or fragments of a wind turbine blade. The method comprises the steps of exposing the wind turbine blade or fragments of a wind turbine blade to an acid to decompose a chemically decomposable polymer; and recovering fibers from the first fiber reinforced plastic and / or the second fiber reinforced plastic. Preferably, the acid comprises formic acid, as formic acid has been found to provide relatively rapid swelling at lower temperatures than most other acids and / or swelling in a practical time. The method enables both the recovered fibers and the decomposed polymer to be reused, for example in the manufacture of new wind turbine blades or other products. This reduces the amount of virgin resources and the carbon footprint required to manufacture wind turbine blades. In particular, recovering monomers from epoxy polymers of non-recyclable resources (such as bisphenol A) directly reduces the demand for fossil-based monomers.

[0021] In an embodiment, the acid swells the acid-cleavable epoxy polymer to form a collection of swollen epoxy polymer particles. The method further comprises collecting the swollen epoxy polymer particles, depolymerizing the swollen epoxy polymer particles, and recovering monomers and / or oligomers of the depolymerized epoxy polymer. The recovered monomers can be reused in new products, such as resins for wind turbine blades. The oligomers can be reused in new resins or further broken down into monomers before being reused in, for example, new resins.

[0022] In an embodiment, the method includes recovering non-fibrous material from a wind turbine blade or fragments of a wind turbine blade, wherein the non-fibrous material optionally includes metal, wood, a non-acid-cleavable epoxy polymer, and / or a partially swollen acid-cleavable epoxy polymer. The non-acid-cleavable epoxy polymer may be, for example, a thermoplastic-based core material or a thermoset resin component of the non-acid-cleavable epoxy polymer, such as a coating or a thermoset composite.

[0023] In one embodiment, the wind turbine blade is broken into pieces prior to exposure to the acid. This has been found to facilitate handling of the wind turbine blade during the disintegration process and may require the removal of parts that are not affected by the swelling process, thus only increasing the volume of the parts being processed without gaining any benefit from the process.

[0024] In one embodiment, the method further comprises removing the spar or spar cap prior to exposure to the acid. It has been found that, in some cases, even though the spar or spar cap may be susceptible to acid cleavage, mechanical separation of these components prior to swelling can better separate the (carbon) fibers of the spar or spar cap from the (glass) fibers of the first fiber reinforced plastic and / or the second fiber reinforced plastic.

[0025] In one embodiment, the acid-cleavable epoxy polymer of the first component has a different property than the acid-cleavable epoxy polymer of the second component, wherein the first component and the second component are different components selected from a first fiber-reinforced plastic, a second fiber-reinforced plastic, and an adhesive. If one or more of the spar and / or spar cap, the coating, the core material, the third fiber-reinforced plastic, and the additional adhesive comprises an acid-cleavable epoxy polymer, then preferably the group also includes an acid-cleavable epoxy polymer comprising the listed components. Preferably, the different properties are at least two properties selected from glass transition temperature, tensile strength, compressive strength, flexural strength, hardness, Young's modulus, transparency, and density. The acid-cleavable epoxy polymer of the first component and the acid-cleavable epoxy polymer of the second component are swellable under a first set of process conditions, wherein the acid-cleavable epoxy polymer of the first component swells faster under the first set of process conditions than the acid-cleavable epoxy polymer of the second component swells under the first set of process conditions. In this embodiment, exposing a wind turbine blade or a fragment of a wind turbine blade to an acid to swell the acid-cleavable epoxy polymer comprises the following steps: first, at least partially swelling a first component and a second component under a first set of process conditions; then, separating the second component from the first component; and then, swelling the second component under a second set of process conditions. This process can be factored into the manufacturing process of wind turbine blades and allows for enhanced swelling separation through blade design, thereby simplifying processing and producing a higher-value recycled product.

[0026] In one embodiment, the acid-cleavable epoxy polymer of the first component has a different property than the acid-cleavable epoxy polymer of the second component, wherein the first component and the second component are different components selected from a first fiber-reinforced plastic, a second fiber-reinforced plastic, and an adhesive. If one or more of the spar and / or spar cap, the coating, the core material, the third fiber-reinforced plastic, and the additional adhesive comprises an acid-cleavable epoxy polymer, then preferably the group also includes an acid-cleavable epoxy polymer comprising the component in that list. Preferably, the different properties are at least two properties selected from the group consisting of glass transition temperature, tensile strength, compressive strength, flexural strength, hardness, Young's modulus, transparency, and density. The acid-cleavable epoxy polymer of the first component is swellable under a first set of process conditions, while the acid-cleavable epoxy polymer of the second component does not chemically decompose under the first set of process conditions. In this embodiment, exposing the wind turbine blade or wind turbine blade fragment to an acid to swell the acid-cleavable epoxy polymer comprises the following steps: first, at least partially swelling the first component under the first set of process conditions; then, separating the second component from the first component; and then, swelling the second component under the second set of process conditions. The process can be factored into wind turbine blade manufacturing and allows for swelling-enhanced separation through blade design, streamlining processing and producing a higher-value reuse product.

[0027] In another aspect, the present invention provides a wind turbine comprising a plurality of wind turbine blades as described above mounted on a hub, wherein the hub is mounted on a nacelle supported by a tower.

[0028] In another aspect, the present invention provides a method for manufacturing a wind turbine blade, comprising: arranging a core material, a first fiber, and an optional third fiber reinforced plastic spar cap in a blade mold, and infusing a resin into the first fibers, preparing a shear web from a second fiber and the resin to form a second fiber reinforced plastic, and optionally preparing a structural spar comprising the third fiber reinforced plastic; assembling the blade shell, the optional structural spar, and the shear web using an adhesive, wherein the first fiber reinforced plastic, the second fiber reinforced plastic, and the adhesive comprise an acid-cleavable epoxy polymer.

[0029] Optionally, the method comprises the step of using as first fibers and / or second fibers fibers recovered from a wind turbine blade in another method of the invention.

[0030] Optionally, the method comprises the step of using as core material core material recovered from a wind turbine blade in another method of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order that this may be more fully understood, the present invention will now be described, by way of example only, with reference to the following drawings, in which like features are assigned like reference numerals, and in which:

[0032] Figure 1 is a schematic perspective view of a wind turbine blade;

[0033] Figure 2 is a schematic cross-sectional view of a wind turbine blade;

[0034] Figure 3 A typical horizontal axis wind turbine is shown; and

[0035] Figure 4 A method of disassembling a wind turbine blade is shown. DETAILED DESCRIPTION

[0036] To provide background information for the present invention, Figure 1 and Figure 2 The structure of an example wind turbine blade is shown. Figure 1 is a schematic perspective view of a wind turbine blade 10, Figure 2 is a schematic cross-sectional view of a wind turbine blade 10. Figure 1 As shown, the blade 10 extends spanwise between a root end 12 and a tip end 14 , and extends chordwise between a leading edge 16 and a trailing edge 18 .

[0037] The blade 10 includes an aerodynamic shell 20 defining a substantially hollow interior space 21. The shell 20 may be constructed from a first shell half 22a and a second shell half 22b joined together at or near the leading edge 16 and the trailing edge 18 by a polymer-based adhesive (not shown).

[0038] The outer shell 20 is a composite structure comprising a core material, such as a polymer-based foam core 24, sandwiched between first fiber-reinforced plastic (FRP) skins of an inner 23 and outer 25. The inner and outer skins 23 and 24 are constructed from multiple layers of fiber materials, such as carbon fiber, glass fiber, and aramid fiber, in the form of non-crimped fabrics, chopped strand mats, or woven fabrics. The outer shell 20 also includes a polymer matrix material that bonds the core material 24 and the fiber materials together to form a unitary structure.

[0039] The outer shell 20 may be reinforced to withstand the loads to which the blade 10 is subjected when in use and to increase the structural rigidity of the blade. Figure 2 In the example shown, the first and second half shells 22a, 22b each include a longitudinally extending reinforcement structure known as a spar cap 30. The spar cap 30 typically comprises a third fiber reinforced plastic 32 comprising a plurality of layers of a third fiber reinforced material laminated with a polymer matrix material. Figure 2In the example shown, the spar caps 30 are embedded within the outer shell 20. However, in other examples, they may be attached to the inner skin 23 of the outer shell 20 using a polymer-based adhesive, such as the additional adhesive 38.

[0040] The housing 20 may optionally include a leading edge protector (not shown) attached to the leading edge 16 of the blade 10 to protect the leading edge 16 of the blade 10 during use. The leading edge protector may be formed from another FRP material comprising multiple layers of fiber-reinforced material laminated with a polymer matrix material. Alternatively, the leading edge protector may be formed solely from a polymer-based material or coating. The leading edge protector may be adhered to the blade using a leading edge adhesive.

[0041] The shell 20 may also include a coating applied to its outer skin 24 for protecting the shell structure 20 from environmental conditions when the blade 10 is in use. The coating may be a polymer-based gel coat or a paint.

[0042] like Figure 1 and Figure 2 As shown, the blade 10 also includes a shear web 35 that extends longitudinally in the span direction within the shell 20 (i.e., within the hollow interior 21 of the blade 10). In some examples, the wind turbine blade 10 may include multiple shear webs 35, such as a trailing edge shear web and a main shear web. Each shear web 35 forms part of a spar structure that is used to absorb bending and torsional loads during use of the blade 10. Figure 2 As shown, the shear web 35 has an upper web flange 36 connected to the inner skin 23 of the first shell half 22a and a lower web flange 37 connected to the inner skin 23 of the second shell half 22b. The shear web 35 is bonded to the shell 20 by a polymer-based additional adhesive 38 located between the upper and lower web flanges 36, 37 and the corresponding inner skin 23 of the shell 20. The shear web 35 comprises a second fiber-reinforced plastic material 39 comprising a second fiber-reinforced material layer held in laminated form by a polymer matrix material.

[0043] The various components comprising blade 10 include one or more polymer-based materials in the form of a matrix material, coating, adhesive, or foam. The polymer-based material can be a thermoset or thermoplastic, but for wind turbine blades, the polymer-based material is typically a thermoset.

[0044] In this example, each polymer-based material used to manufacture blade 10 is designed to swell when exposed to an acid, such as acetic acid or formic acid. For example, each polymer-based material can be designed to decompose into monomers and / or oligomers when exposed to a concentration of 20% to 50% formic acid in water. In this way, one or more polymer-based materials can be decomposed by any combination of softening, swelling, disintegration, and / or acid cleavage, thereby allowing the fiber reinforcement material to be released from the various components comprising blade 10 and recovered for reuse.

[0045] The polymer systems comprising the various polymer-based materials of the blade 10 are preferably selected to minimize the number of decomposition steps required. This can be achieved by using acid-cleavable epoxy polymers (which are swellable under the same or similar process conditions) to form the various polymer-based components of the blade 10. However, preferably, all polymer-based materials comprising the blade 10 are based on acid-cleavable epoxy polymers that are swellable under the same process conditions, so that this set of process conditions can be used to disintegrate all polymer-based materials of the blade 10 to allow for the recovery and reuse of the fiber reinforcement material and the epoxy polymer material itself (e.g., via depolymerization).

[0046] In an alternative example, the various polymer-based components comprising the blade 10 can be based on two or more different polymer systems, wherein the acid-cleavable epoxy polymer can be reused via swelling, while the other polymer system can be reused in other ways after separation from the swollen epoxy polymer particles. Two different acid-cleavable epoxy polymers can also be present. For example, the acid-cleavable epoxy polymer of the additional adhesive 38, as well as any other acid-cleavable epoxy polymers used to form the adhesive of the blade 10 (such as the adhesive connecting the first half-shell 22a and the second half-shell 22b), can be based on a first acid-cleavable epoxy polymer that requires a first set of swelling process conditions, while the acid-cleavable epoxy polymers of some or all of the other components of the blade 10 are based on a second acid-cleavable epoxy polymer that requires a second set of decomposition process conditions to achieve rapid swelling, or at least swells much more slowly under the first set of swelling process conditions than the first acid-cleavable epoxy polymer.

[0047] In the example above, the bonded components of the blade can be first separated by being subjected to a first set of process conditions, and then separated by swelling of the first acid-cleavable epoxy polymer in the adhesive and the additional adhesive. The remaining blade components can then be processed under a second set of process conditions. This approach can also be useful, for example, to allow the fiber material of the outer shell 20 to be released and recovered separately from the fiber material of the shear web 35. This can advantageously reduce the need for a secondary fiber sorting process when the fiber composition of the outer shell 20 differs from that of the shear web 35.

[0048] The second acid-cleavable epoxy polymer may be largely unaffected by the first set of process conditions, or the second acid-cleavable epoxy polymer may begin to decompose during exposure to the first set of process conditions. For example, the second acid-cleavable epoxy polymer may soften during exposure to the first set of process conditions but may not swell to an extent that causes the second acid-cleavable epoxy polymer to disintegrate. This may be beneficial, for example, by allowing components made from the second acid-cleavable epoxy polymer to be broken into smaller pieces during exposure to the second set of process conditions for faster processing.

[0049] It should be understood that the above discussion provides examples only, and that the various components of the blade 10 may be manufactured using any number of acid-cleavable epoxy polymers and any number of required sets of swelling process conditions.

[0050] In all the above examples, the temperature of the acidic solution can be increased to accelerate the rate of chemical decomposition. For example, the temperature of the acidic solution can be between 60°C and 90°C.

[0051] Figure 3 A wind turbine 1 comprising a plurality of wind turbine blades 10 is shown. Figure 3 The wind turbine 1 shown is representative of a typical horizontal axis wind turbine (HAWT) and comprises a tower 2, a nacelle 3 mounted at the apex of the tower 2, and a rotor hub 4 supported on the nacelle 3. Three wind turbine blades 10 are supported by the rotor hub 4.

[0052] Now go to Figure 4 , a method of disassembling a wind turbine blade 10 configured as described above is shown. In this example, all polymer-based components of the blade 10 are based on acid-cleavable epoxy polymers.

[0053] In a first step, the blade 10 is mechanically divided into smaller blade fragments 50, such as by sawing, grinding, or crushing. The blade fragments 50 are then exposed to an acid solution 42, for example, by soaking or spraying the blade fragments 50 in a water-based solution having a concentration of 40% formic acid. The acid solution 42 is heated to 85°C before the blade fragments 50 are immersed in the solution 42 and maintained at 85°C throughout the swelling process. In addition to ambient temperature (equivalent to no heating), other temperatures are also possible, requiring a trade-off between evaporation, heating, and process time.

[0054] Exposure of the blade fragments 50 to the acid solution 54 causes the acid-cleavable epoxy polymer to swell, thereby converting the acid-cleavable epoxy polymer in the blade 10 into swollen epoxy polymer particles while leaving intact the fiber reinforcement and components in the skin, spar caps, and shear webs that are not acid-cleavable polymers. The swelling of the acid-cleavable epoxy polymer structure causes these materials to soften, swell, and / or disintegrate in the acid, thereby releasing the fiber reinforcement and other non-swellable components.

[0055] The treatment of the blade 10 typically takes from 10 minutes to several days or even weeks, depending on the process conditions and the acid-cleavable epoxy polymer used. Once the acid-cleavable epoxy polymer material has been sufficiently disintegrated, the fiber reinforcement material can be recovered from the bath 52, for example by filtering the mixture of formic acid, swollen epoxy polymer particles and blade residue. The fiber reinforcement material can then be cleaned and reused as a dry fiber material 55 for recycling. In one example, the dry fiber material 55 can be chopped and used to produce a chopped strand mat made of randomly oriented chopped fibers. If the fiber reinforced plastic material includes multiple fiber types and a step-by-step disintegration process is not used, an additional fiber sorting step may be required.

[0056] After the fiber reinforcement material 55 is removed from the acid bath 52, the swollen epoxy polymer material particles 56 can be extracted from the acid solution 54 using appropriate separation techniques (e.g., filtration or spray drying). The recovered swollen epoxy polymer material particles 57 can be reused using known techniques (e.g., depolymerization), and the remaining formic acid 54 can be reused in the subsequent decomposition process of the wind turbine blade.

[0057] Any metal or other non-polymer material (such as wood) may also be recovered from the trough 52. In an alternative example, any mechanically removable metal (or other material) components may be removed from the blade 10 before the blade 10 is exposed to the acidic solution 54. In a further alternative example, the spars, spar caps 30, and / or shear webs 35 may be removed from the blade 10 before the blade shell 20 is exposed to the acidic solution 54.

[0058] It will be understood by those skilled in the art that the above-described specific embodiments may be modified without departing from the inventive concept defined in the claims.

Claims

1. A wind turbine blade comprising: A blade shell comprising a core material and a first fiber reinforced plastic, a shear web comprising a second fiber reinforced plastic, and Adhesives, wherein the shear web is adhered to the blade shell by adhesive, and The first fiber-reinforced plastic, the second fiber-reinforced plastic, and the adhesive each comprise an acid-cleavable epoxy polymer.

2. The wind turbine blade according to claim 1, wherein: The acid-cleavable epoxy polymers in each of the first fiber-reinforced plastic, the second fiber-reinforced plastic and the adhesive are acid-cleavable in an acidic fluid comprising acetic acid and / or formic acid. Preferably, the acid-cleavable epoxy polymers in each of the first fiber-reinforced plastic, the second fiber-reinforced plastic and the adhesive are based on amine-cured epoxy resins.

3. The wind turbine blade according to claim 1 or 2, further comprising: A spar and / or spar cap includes a third fiber reinforced plastic including an acid-cleavable epoxy polymer.

4. The wind turbine blade according to any one of the preceding claims, further comprising at least one wind turbine blade coating arranged on the blade shell, wherein the blade coating comprises an acid-cleavable epoxy polymer.

5. A wind turbine blade according to any one of the preceding claims, wherein The core material is a foam core and comprises an acid-cleavable epoxy polymer.

6. A wind turbine blade according to any one of the preceding claims, wherein properties of a first component differ from properties of a second component, wherein the first component and the second component are different components selected from the group consisting of a first fiber reinforced plastic, a second fiber reinforced plastic, and an adhesive.

7. A wind turbine blade according to any one of the preceding claims, wherein: The properties of the acid-cleavable epoxy polymer of the first component are different from the properties of the acid-cleavable epoxy polymer of the second component, wherein the first component and the second component are different components selected from the group consisting of a first fiber reinforced plastic, a second fiber reinforced plastic, and an adhesive.

8. A wind turbine blade according to any one of the preceding claims, wherein The acid-cleavable epoxy polymers in each of the first fiber-reinforced plastic, the second fiber-reinforced plastic, and the adhesive are acid-decomposable under the same process conditions.

9. A wind turbine blade according to claim 6 or 7, wherein: The acid-cleavable epoxy polymer of the first component and the acid-cleavable epoxy polymer of the second component are swellable under a first set of process conditions, wherein the acid-cleavable epoxy polymer of the first component swells faster under the first set of process conditions than the acid-cleavable epoxy polymer of the second component swells under the first set of process conditions.

10. A method of breaking up a wind turbine blade or fragments of a wind turbine blade according to any one of claims 1 to 9, comprising the steps of: exposing the wind turbine blade or a fragment of the wind turbine blade to an acid to disintegrate the acid-cleavable epoxy polymer into swollen epoxy polymer particles; preferably, the acid comprises formic acid, and Fibers are recovered from the first fiber-reinforced plastic and / or the second fiber-reinforced plastic.

11. The method according to claim 10, further comprising the steps of: The swollen epoxy polymer particles are collected, the swollen epoxy polymer particles are depolymerized, and monomers and / or oligomers of the depolymerized epoxy polymer are recovered.

12. The method according to claim 10 or 11, further comprising recovering non-fibrous material from the wind turbine blade or the fragments of the wind turbine blade, wherein optionally, the non-fibrous material comprises at least one of metal, wood, unswollen polymer and swollen epoxy polymer particles.

13. The method of any one of claims 10 to 12, further comprising breaking the wind turbine blade into fragments prior to exposing to the acid.

14. A method according to any one of claims 10 to 13, further comprising removing the spar or spar cap prior to exposure to acid.

15. The method according to any one of claims 10 to 14, wherein the properties of the acid-cleavable epoxy polymer of the first component are different from the properties of the acid-cleavable epoxy polymer of the second component, wherein the first component and the second component are different components selected from a first fiber reinforced plastic, a second fiber reinforced plastic, and an adhesive, and The acid-cleavable epoxy polymer of the first component and the acid-cleavable epoxy polymer of the second component are swellable under a first set of process conditions, wherein the acid-cleavable epoxy polymer of the first component swells faster under the first set of process conditions than the acid-cleavable epoxy polymer of the second component swells under the first set of process conditions, and exposing the wind turbine blade or a fragment of the wind turbine blade to an acid to swell the acid-cleavable epoxy polymer comprises the steps of: The acid-cleavable epoxy polymers of the first and second assemblies are first at least partially swollen to form swollen epoxy polymer particles under a first set of process conditions, the second assembly is separated from the first assembly, and the acid-cleavable epoxy polymers of the second assembly are then swollen under a second set of process conditions.

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