All-component comprehensive utilization method of waste fan blade

Abstract

The invention discloses a comprehensive utilization method for all components of waste fan blades. The method comprises the following steps that S1, according to the structure of the fan blade, the waste fan blade is cut and classified, a separated inorganic crushed material serves as a filling material of a structural component, and a separated glass fiber reinforced resin composite material and structural adhesive are to be treated; s2, cutting and crushing the glass fiber reinforced resin composite material and the structural adhesive, putting the glass fiber reinforced resin composite material and the structural adhesive into a reaction container filled with an acetic acid aqueous solution, and reacting at normal pressure; s3, filtering a reaction solution obtained after the reaction in the step S2 is finished to obtain a liquid-phase product and regenerated fibers, and distilling the liquid-phase product to respectively obtain acetic acid, bisphenol A and organic residues; and S4, gasifying the organic residues and powder generated in the cutting process together to obtain the synthesis gas. According to the method provided by the invention, efficient utilization of the main components of the composite material, the structural adhesive, the foam and the balsa wood in the fan blade is realized, and the comprehensive utilization rate is high.

Description

Technical Field

[0001] The present invention relates to the technical field of recycling and regeneration of retired new energy devices, and in particular to a method for comprehensive utilization of all components of waste wind turbine blades. Background Art

[0002] Over the past two decades, wind energy has been widely adopted, with global wind power generation capacity projected to reach 2,015 GW by 2030. Wind turbines must be decommissioned after reaching their design lifespan (approximately 20-30 years). Approximately 10,000 tons of blade material are required for each GW of installed capacity. Unlike the mechanical components of wind turbines, which are easily recyclable and have economic value, the three-dimensional cross-linked structure of blade materials makes them difficult to decompose and economically unviable for recycling. By 2050, an estimated 43 million tons of discarded wind turbine blades are expected to be generated.

[0003] Wind turbine blades are primarily composed of glass fiber-reinforced resin composites, lightweight wood (or foam), and structural adhesives. Fiber accounts for approximately 60% of the blade's composition, while thermosetting resin accounts for approximately 30%. Epoxy resin is widely used in wind turbine blades due to its structural stability and corrosion resistance. In addition to glass fiber, carbon fiber, with its excellent fatigue resistance and strength, is gaining popularity.

[0004] At present, the comprehensive utilization rate of waste wind turbine blades is low. Energy recovery can utilize various organic components, but burning resins will increase carbon emissions and release toxic gases, and the fiber performance will also be damaged due to the high-temperature oxidation process. Physical recycling seems to be a more environmentally friendly method, cutting or crushing the blades and using them as filling materials for structural components. However, this method consumes very little waste wind turbine blades, and physically recovered materials will still need further processing in the future. Pyrolysis can depolymerize resins well to obtain clean fibers. However, the resources of the scraps after cutting are insufficiently utilized, and the traditional pyrolysis method has problems such as low retention of fiber mechanical properties, low value of resin depolymerization products, and difficulty in reuse. Summary of the Invention

[0005] The present invention solves the problems existing in the prior art and provides a method for comprehensive utilization of all components of waste fan blades. The method proposed by the present invention realizes the efficient utilization of the main components of composite materials, structural adhesives, foam and balsa wood in the fan blades, and has a high comprehensive utilization rate.

[0006] The present invention is achieved through the following technical solutions:

[0007] The purpose of the present invention is to provide a method for comprehensive utilization of all components of waste fan blades, comprising the following steps:

[0008] S1. Precisely cut and sort the used wind turbine blades according to their structure. The separated glass fiber reinforced resin composite materials and structural adhesives are processed. The crushed materials other than the composite materials and structural adhesives are used as filling materials for structural components. The crushed materials include foam and balsa wood.

[0009] S2. Cut and crush the glass fiber reinforced resin composite material and structural adhesive obtained in step S1, and then put them into a reaction vessel filled with acetic acid aqueous solution, and react at 140° C. to 250° C. under normal pressure for 4 to 10 hours;

[0010] S3. Filter the reaction solution obtained after the reaction in step S2 to obtain a liquid product and regenerated fiber. The regenerated fiber is used to prepare a glass fiber reinforced resin composite material. The liquid product is distilled to obtain acetic acid, bisphenol A, and an organic residue. The bisphenol A is collected for preparing an epoxy resin. The acetic acid is recovered and returned to step S2 for recycling.

[0011] S4. The organic residue obtained in step S3 and the powder generated during the cutting process in steps S1 and S2 are gasified together to obtain synthesis gas.

[0012] The proposed method improves comprehensive utilization by precisely cutting, sorting, and reusing various parts of used wind turbine blades. Foam and balsa wood are used as fillers for structural components. For fiber-reinforced resin composites and epoxy-based structural adhesives, microwave-assisted dissolution is used to depolymerize the resin to produce bisphenol A and recover the fibers. The remaining organic components are then gasified to produce syngas.

[0013] Since the structural adhesive used to bond the various parts of the wind turbine blade is mainly epoxy resin, in step S1, the structural adhesive portion is retained on the composite material side during cutting, and the reaction in step S2 can be carried out together with the composite material, while ensuring the purity of the foam and balsa wood.

[0014] Preferably, in step S2, the mass ratio of the total mass of the glass fiber reinforced resin composite material and the structural adhesive to the acetic acid aqueous solution is 1:5-20, and the mass ratio of acetic acid to water in the acetic acid aqueous solution is 2-9:1. In step S2, the large-sized composite material is cut and thinned to reduce its volume to facilitate heat and mass transfer during the reaction. Mechanical stirring is performed during the reaction in step S2.

[0015] Further preferably, in step S2, the mass ratio of the total mass of the glass fiber reinforced resin composite material and the structural adhesive to the acetic acid aqueous solution is 1:10, and the mass ratio of acetic acid to water in the acetic acid aqueous solution is 9:1.

[0016] Preferably, in step S2, microwave heating is performed at 140° C. to 250° C. for 4 to 10 hours. During the reaction, the reaction tank is blown with air to dissipate heat, thereby increasing the microwave power in the constant temperature stage and accelerating the reaction.

[0017] More preferably, in step S2, the reaction is heated to 220° C.-230° C. by microwave heating for 6 h.

[0018] Preferably, the distillation conditions in step S3 are: distillation temperature of 130° C., reflux ratio of 0.025, to separate acetic acid; and the remaining product is further distilled at 0.5 atm and 340° C. to separate bisphenol A.

[0019] Preferably, the gasification process in step S4 is performed in a fixed-bed gasifier or a fluidized-bed gasifier. The reactants are fed into an oxygen-enriched atmosphere containing water and CO₂ in a certain ratio. Gasification proceeds at a temperature of 900°C to 1400°C and a pressure of 1.2 to 1.6 MPa to produce crude syngas. The specific amounts of water and CO₂ added are controlled based on the ratio of hydrogen to carbon monoxide in the product. More preferably, the mass ratio of the gasifying agent water to the raw materials is 1.5 to 10 mg / g, and the mass ratio of water to CO₂ is 2 to 8:1.

[0020] The gasification process in step S4 is equipped with both waste heat recovery and gas purification. After rapid cooling and purification, the crude syngas is purified to produce a suitable proportion of pure syngas. The collected waste heat is then used in the distillation process. The resulting solid residue undergoes a carbon removal process to produce pure chopped fibers, which are then returned to step S1 for use as filler material for structural components.

[0021] More preferably, the crude synthesis gas is purified to obtain pure synthesis gas, and the collected waste heat is used in the distillation process in step S3 to perform a carbon removal process on the generated inorganic fragments to obtain pure chopped fibers, which are returned to step S1 for use as filling materials for structural components.

[0022] More preferably, the gasification conditions are: gasification temperature 1200° C., gasification pressure 1.4 MPa.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The method proposed in this invention achieves efficient utilization of the main components of wind turbine blades: composite materials, structural adhesives, foam, and balsa wood, achieving a high overall utilization rate. Microwave-assisted solvent dissolution of the composite materials and structural adhesives yields clean fibers, bisphenol A, and organic residues. The fibers can be reused in wind turbine blades or other composite materials. The bisphenol A can be used as a monomer in the production of epoxy resins, and the remaining organic residues are gasified to produce synthesis gas. The foam, balsa wood, and inorganic crushed materials can be used as filler materials for structural components.

[0025] 2. Compared with the pyrolysis method, the present invention utilizes microwave-assisted acetic acid dissolution method, which has high energy utilization rate, mild reaction conditions, low energy consumption, and can also promote the swelling of thermosetting epoxy resin, which is beneficial to heat and mass transfer.

[0026] 3. The liquid products obtained by thermal decomposition are mixed, and bisphenol A easily decomposes. The product selectivity is poor and the value is low, mainly monocyclic phenols. The aqueous acetic acid system can selectively break the CO bond without deeply breaking the CC bond, thus obtaining high-value bisphenol A.

[0027] 4. This invention also effectively utilizes the organic residues left after resin depolymerization and the dust generated by cutting. These materials have lower volume and molecular weight than the raw materials, resulting in high heat and mass transfer efficiency and a high atomic utilization rate during the gasification process. This co-production method helps reduce energy consumption in the gasification process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic flow chart of the method for comprehensive utilization of all components of waste fan blades according to the present invention;

[0029] Figure 2 This is the liquid product distribution diagram in Example 1. DETAILED DESCRIPTION

[0030] The present invention will be described in further detail below with reference to the following examples. These examples are intended to illustrate the present invention only and are not intended to limit the scope of the invention. Experimental methods in the following examples, where specific conditions are not specified, generally follow conventional conditions in the art or the conditions recommended by the manufacturer; raw materials and reagents used, unless otherwise specified, are deemed to be commercially available through conventional markets. In the following examples, the specific amounts of water and CO2 added are regulated based on the ratio of hydrogen to carbon monoxide in the product.

[0031] Example 1

[0032] like Figure 1 As shown, a method for comprehensive utilization of all components of waste fan blades includes the following steps:

[0033] S1. Used wind turbine blades removed from decommissioned wind turbines are cut and sorted according to their material composition. Leaving the structural adhesive on the composite side during the cutting process ensures the purity of the foam and balsa wood, facilitating subsequent applications. Furthermore, since the structural adhesive is typically made from epoxy resin, it can react with the fiber-reinforced resin composite material in the next step.

[0034] S2, while ensuring the fiber length, before the solution dissolves, the large-sized blades are cut, crushed and thinned, and then the blades are placed in a microwave reactor equipped with a stirring device. After adding 90wt.% acetic acid aqueous solution, the reaction begins. The reaction temperature is 220°C and maintained for 6 hours. The mass ratio of the composite material (including the composite material and structural adhesive in step S1) to the acetic acid aqueous solution is 1:10. During the reaction, air is blown toward the outer wall of the reactor to accelerate heat dissipation, thereby increasing the microwave power during the constant temperature stage.

[0035] S3. After the reaction is completed, the fibers are filtered and washed to obtain regenerated fibers for use in preparing fiber-reinforced resin composite materials. The filtered liquid product is then fed into a distillation apparatus under the following conditions: a distillation temperature of 130°C and a reflux ratio of 0.025 to separate the acetic acid. The remaining product is further distilled at 0.5 atm and 340°C to separate bisphenol A, thereby separating bisphenol A, acetic acid, and organic residues. The acetic acid is recovered and recycled.

[0036] S4: The organic residue remaining after solvent evaporation, along with the dust generated by cutting in steps S1 and S2, is fed into a gasifier for reforming and gasification at 1200°C and 1.4 MPa. Simultaneously, an oxygen-enriched atmosphere containing a certain ratio of water and CO2 (the mass ratio of the gasifying agent water to the raw material is 6 mg / g, and the mass ratio of water to CO2 is 5:1) is introduced to adjust the H2-CO ratio in the syngas. The crude syngas obtained during the gasification process is rapidly cooled by a cooling unit and then passed through a gas purification unit (with alcohol washing and then alkaline washing) to obtain clean syngas composed primarily of H2 and CO. The remaining inorganic scrap is then oxidized and decarbonized to produce clean short fibers, which can be woven into fiber mats or incorporated into concrete. The high-temperature exhaust gas from the gasifier is passed through a waste heat boiler to generate steam for use in the distillation process. These recycling methods can reduce carbon emissions and improve energy efficiency.

[0037] Through this process, the foam and balsa wood are fully recycled; the tensile strength of the recycled glass fiber is retained at over 95%, and both long and short fibers can be reused in different applications. The molar yield of bisphenol A is 38%, the gasification rate of the remaining organic components is 78%, and the effective gas content in the syngas is 75% (32% H2, 43% CO). The comprehensive recovery rate of used fan blades is over 95%.

[0038] Comparative Example 1

[0039] The same as Example 1, except that: in step S2, conventional electric heating is used instead of microwave heating.

[0040] Through the same process, foam and balsa wood can be fully recycled; the tensile strength retention rate of recycled glass fiber reaches more than 95%, and both long and short fibers can be reused in different scenarios; the molar yield of bisphenol A is 21%, the gasification rate of the remaining organic components is 74%, and the effective gas content in the synthesis gas is 75%.

[0041] Comparative Example 2

[0042] The same as Example 1, except that in step S2, the acetic acid aqueous solution is replaced by isopropanol aqueous solution for reaction.

[0043] After the same process, the degradation rate of the composite material was only 62%, a large amount of resin was attached to the fibers, and no bisphenol A was detected in the degradation products.

[0044] Comparative Example 3

[0045] The same as Example 1, except that: in step S2, a thermal decomposition method is used, and the reaction is carried out at 550° C. for 1 hour.

[0046] After the same process, the tensile strength retention rate of the regenerated glass fiber was 88%, the molar yield of bisphenol A was 15%, the gasification rate of the remaining organic components was 82%, and the effective gas content in the synthesis gas was 80%.

[0047] Compared with Comparative Example 1, Example 1 shows that microwaves have a reinforcing effect on acetic acid dissolution, which can promote the dissolution of the resin in a shorter time, and the generation efficiency of bisphenol A is higher. Comparative Example 2 takes isopropyl alcohol as an example. Other commonly used solvents have poor solubility for epoxy resins and cannot depolymerize to bisphenol A under mild (microwave) conditions. The microwaves proposed in the present invention have a synergistic effect with acetic acid, promoting the swelling of thermosetting epoxy resins, high heat and mass transfer efficiency, high energy utilization, mild reaction conditions, and promoting the generation of bisphenol A. Comparative Example 3 shows that when the composite material is pyrolyzed, the connecting bonds in the resin are not selectively broken, and bisphenol A will decompose into phenol, isopropylphenol, and isopropenylphenol.

[0048] Example 2

[0049] The difference from Example 1 is that this example uses waste wind turbine blades reinforced with carbon fiber. Due to the excellent microwave absorption ability of carbon fiber, after 4 hours of microwave-assisted reaction in a 90 wt.% acetic acid solution, the resin on the fiber surface is almost completely dissolved.

[0050] Through the same process, foam and balsa wood can be fully recycled; the tensile strength retention rate of recycled carbon fiber reaches over 97%; the molar yield of bisphenol A is 44%, the gasification rate of residual organic components is 76%, and the effective gas content in the syngas is 77%. The comprehensive recovery rate of used fan blades is over 95%.

[0051] Example 3

[0052] The same as Example 1, except that: in step S2, the mass ratio of the composite material to the acetic acid aqueous solution is 1:20, the mass ratio of acetic acid to water in the acetic acid aqueous solution is 2:1, and the reaction is heated to 220° C. by microwave for 6 hours.

[0053] The resin was not completely degraded, with a degradation rate of 84%. The molar yield of bisphenol A was 23%, the gasification rate of the remaining organic components was 75%, and the effective gas content in the synthesis gas was 74%.

[0054] Example 4

[0055] The same as Example 1, except that: in step S2, the mass ratio of the composite material to the acetic acid aqueous solution is 1:5, the mass ratio of acetic acid to water in the acetic acid aqueous solution is 9:1, and the reaction is heated to 230° C. by microwave for 6 hours.

[0056] The tensile strength retention rate of the regenerated glass fiber reaches more than 95%, the molar yield of bisphenol A is 34%, the gasification rate of the remaining organic components is 80%, and the effective gas content in the synthesis gas is 76%.

[0057] The description of the above embodiments is only used to help understand the technical solution and core ideas of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention. These improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for comprehensive utilization of all components of waste fan blades, characterized in that: The steps include: S1. Precisely cut and sort the used wind turbine blades according to their structure. The separated glass fiber reinforced resin composite materials and structural adhesives are processed. The crushed materials other than the composite materials and structural adhesives are used as filling materials for structural components. The crushed materials include foam and balsa wood. S2. Cut and crush the glass fiber reinforced resin composite material and structural adhesive obtained in step S1, and then put them into a reaction vessel filled with acetic acid aqueous solution, and react at 140° C. to 250° C. under normal pressure for 4 to 10 hours; S3. Filter the reaction solution obtained after the reaction in step S2 to obtain a liquid product and regenerated fiber. The regenerated fiber is used to prepare a glass fiber reinforced resin composite material. The liquid product is distilled to obtain acetic acid, bisphenol A, and an organic residue. The bisphenol A is collected for preparing an epoxy resin. The acetic acid is recovered and returned to step S2 for recycling. S4. The organic residue obtained in step S3 and the powder generated during the cutting process in steps S1 and S2 are gasified together to obtain synthesis gas.

2. The method for comprehensive utilization of all components of waste fan blades according to claim 1, characterized in that: In step S2, the mass ratio of the total mass of the glass fiber reinforced resin composite material and the structural adhesive to the acetic acid aqueous solution is 1:5-20, and the mass ratio of acetic acid to water in the acetic acid aqueous solution is 2-9:

1.

3. The method for comprehensive utilization of all components of waste fan blades according to claim 2, characterized in that: In step S2, the mass ratio of the total mass of the glass fiber reinforced resin composite material and the structural adhesive to the acetic acid aqueous solution is 1:10, and the mass ratio of acetic acid to water in the acetic acid aqueous solution is 9:

1.

4. The method for comprehensive utilization of all components of waste fan blades according to claim 1, characterized in that: In step S2, the mixture is heated to 140° C.-250° C. by microwave for 4-10 h.

5. The method for comprehensive utilization of all components of waste fan blades according to claim 4 is characterized in that: In step S2, the mixture is heated to 220° C.-230° C. by microwave and reacted for 6 h.

6. The method for comprehensive utilization of all components of waste fan blades according to claim 1, characterized in that: The distillation conditions in step S3 are: distillation temperature of 130° C., reflux ratio of 0.025, to separate acetic acid; the remaining product is further distilled at 0.5 atm and 340° C. to separate bisphenol A.

7. The method for comprehensive utilization of all components of waste fan blades according to claim 1, characterized in that: In step S4, the gasification process adopts a fixed bed gasifier or a fluidized bed gasifier, inputs the reaction materials, introduces an oxygen-rich atmosphere with a certain proportion of water and CO2, and gasifies under temperature conditions of 900°C-1400°C and pressure conditions of 1.2-1.6MPa to obtain crude synthesis gas.

8. The method for comprehensive utilization of all components of waste fan blades according to claim 7 is characterized in that: After the crude synthesis gas is purified, pure synthesis gas is obtained. The collected waste heat is used in the distillation process in step S3. The generated inorganic fragments are subjected to a carbon removal process to obtain pure fragmented fibers, which are returned to step S1 and used as filling materials for structural components.

9. The method for comprehensive utilization of all components of waste fan blades according to claim 7, characterized in that: The gasification conditions are: gasification temperature 1200° C., gasification pressure 1.4 MPa.

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