A wind turbine blade recycling method based on hydrothermal pyrolysis

Abstract

The present application discloses a method for recycling wind turbine blades based on hydrothermal pyrolysis, which includes: carrying out a catalytic hydrogenation reaction on wind turbine blades and an organic solvent in a hydrogen atmosphere under the action of a hydrogenation catalyst, and then carrying out catalytic pyrolysis to recover glass fibers. In the method for recycling wind turbine blades based on hydrothermal pyrolysis described in the present application, catalytic hydrogenation is carried out on the wind turbine blades before pyrolysis, converting the benzene rings (derived from bisphenol A segments) in the polymer chains of the blade matrix resin into alicyclic structures, which can not only significantly reduce the resin pyrolysis temperature, but also reduce the formation of pyrolytic carbon. These are all helpful for improving the subsequent pyrolysis efficiency and the quality of recycled fibers, reducing the recycling cost, and at the same time reducing the generation of dioxins and secondary pollution to the atmosphere.

Description

Technical Field

[0001] This application relates to the technical field of solid waste treatment, and particularly relates to a method for recycling wind turbine blades based on hydro-pyrolysis. Background Art

[0002] In recent years, with the rapid increase in the installed capacity of wind power and the gradual retirement of the first batch of operating wind turbines, the number of waste wind turbine blades has been increasing day by day, becoming a kind of high-value industrial solid waste that urgently needs to be treated. Wind turbine blades are mainly fiber-reinforced resin-based composites. Pyrolysis is a common method for recycling composites. Usually, under specific atmosphere and high temperature (≥850 °C), the matrix resin of the composite is converted into gaseous small molecule compounds to recover the high-value reinforcing fibers, realizing resource utilization. However, this method has disadvantages such as high energy consumption and large thermal damage to the recycled fibers when treating waste blades. Therefore, developing a new pyrolysis technology is of great significance for the recycling of wind turbine blades. Summary of the Invention

[0003] This application aims to provide a method for recycling wind turbine blades based on hydro-pyrolysis. Before pyrolysis, catalytic hydrogenation is carried out on the wind turbine blades to change the benzene rings (derived from bisphenol A segments) in the polymer chains of the blade matrix resin into alicyclic ring structures, which can not only significantly reduce the resin pyrolysis temperature, but also reduce the formation of cracked carbon. These are all helpful to improve the subsequent pyrolysis efficiency and the quality of recycled fibers, reduce the recycling cost, and at the same time reduce the generation of dioxins and secondary pollution to the atmosphere.

[0004] To this end, an embodiment of this application provides a method for recycling wind turbine blades based on hydro-pyrolysis, including:

[0005] Carrying out a catalytic hydrogenation reaction on the wind turbine blades and an organic solvent in a hydrogen atmosphere under the action of a hydrogenation catalyst, and then catalytic pyrolysis to recover glass fibers.

[0006] In some embodiments, the temperature of the catalytic hydrogenation reaction is 150 - 160 °C.

[0007] In some embodiments, the pressure of the catalytic hydrogenation reaction is 2.8 - 5.2 MPa.

[0008] In some embodiments, the time of the catalytic hydrogenation reaction is 5 - 6 h.

[0009] In some embodiments, the catalyst for the catalytic hydrogenation reaction is a ruthenium-carbon catalyst.

[0010] In some embodiments, the organic solvent is at least one of isopropanol, n-butanol, and cyclohexane.

[0011] In some embodiments, the mass ratio of the wind power blade, the organic solvent and the hydrogenation catalyst is (16 - 24):(64 - 96):(0.8 - 1.2), preferably 20:80:1.

[0012] In some embodiments, the catalytic hydrogenation reaction process is as follows: add the wind power blade, the organic solvent and the hydrogenation catalyst into a high-pressure reactor, then displace the air in the high-pressure reactor with hydrogen, and then fill the high-pressure reactor with hydrogen, heat to the reaction temperature, and carry out the reaction under stirring.

[0013] In some embodiments, the pyrolysis temperature is 280 - 330 °C.

[0014] In some embodiments, the pyrolysis atmosphere is a mixed gas composed of nitrogen and oxygen, and the volume content of oxygen is 6 - 8%.

[0015] In some embodiments, the pyrolysis time is 3 - 4 h.

[0016] In some embodiments, the pyrolysis is carried out in a pyrolysis furnace.

[0017] The wind power blade recovery method based on hydro-pyrolysis according to the embodiments of the present application can bring the following beneficial effects:

[0018] (1) The matrix resin of the wind power blade is generally bisphenol A epoxy resin. Before pyrolysis, the benzene ring in the epoxy resin polymer chain is catalytically hydrogenated to convert it into a fat ring structure with lower thermal stability, and then pyrolysis is carried out. Its pyrolysis temperature is much lower than that of the traditional pyrolysis method. Therefore, the energy consumption of the blade recovery method disclosed in the present application is lower than that of the traditional pyrolysis method.

[0019] (2) Before pyrolysis in the present application, the benzene ring structure with strong char-forming property is first converted into a fat ring, which can reduce the formation of pyrolysis carbon, improve the purity of the recovered fiber, and at the same time reduce the formation of dioxins in the tail gas and the secondary environmental pollution caused by it.

[0020] (3) The equipment and devices involved in the catalytic hydrogenation process and the pyrolysis process in the present application are all industrial products, which are easy to be implemented in engineering.

[0021] The additional aspects and advantages of the present application will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the present application. Detailed Embodiments

[0022] The embodiments of the present application will be described in detail below. The examples of the embodiments are exemplary and are intended to explain the present application, and should not be construed as a limitation to the present application.

[0023] In an application, the disclosure of a numerical range includes the disclosure of all values within the entire range and further sub-ranges, including the endpoints and sub-ranges given for these ranges.

[0024] In an application, the raw materials, equipment, etc. involved, unless otherwise specified, are raw materials and equipment that can be obtained through commercial channels or made by known methods; the methods involved, unless otherwise specified, are conventional methods.

[0025] The wind turbine blade recycling method based on hydrothermal pyrolysis according to the embodiments of the present application includes the following steps:

[0026] S100: Catalytic hydrogenation reaction is carried out on the wind turbine blade and the organic solvent in a hydrogen atmosphere under the action of a hydrogenation catalyst.

[0027] S200: Catalytic pyrolysis is carried out on the product after the catalytic hydrogenation reaction in step S100 to recover glass fibers.

[0028] In the wind turbine blade recycling method based on hydrothermal pyrolysis according to the embodiments of the present application, before pyrolysis, catalytic hydrogenation is carried out on the wind turbine blade to catalytically reduce the benzene ring structure in the blade matrix resin (usually bisphenol A epoxy resin) into a cyclohexane structure, so as to reduce the thermal stability of the matrix resin, thereby significantly reducing the pyrolysis temperature of the resin, reducing the thermal damage of the recycled fibers and reducing the energy consumption for recycling. After changing the benzene ring in the polymer chain of the matrix resin into an aliphatic ring structure, the formation of pyrolysis carbon can be effectively reduced. On the one hand, the resin residue rate on the fiber surface can be reduced, and the purity of the recycled fibers can be improved; on the other hand, the generation of dioxins in the pyrolysis tail gas can be reduced, and the secondary pollution of the tail gas to the environment can be reduced.

[0029] In some embodiments, in step S100, the mass ratio of the wind turbine blade, the organic solvent and the hydrogenation catalyst is (16 - 24):(64 - 96):(0.8 - 1.2), preferably 20:80:1.

[0030] In some embodiments, the catalytic hydrogenation reaction in step S100 is carried out in a high-pressure reaction kettle.

[0031] In some embodiments, the temperature of the catalytic hydrogenation reaction in step S100 is 150 - 160 °C, such as 155 °C, etc.

[0032] In some embodiments, the pressure of the catalytic hydrogenation reaction in step S100 is 2.8 - 5.2 MPa, such as 4 MPa, etc.

[0033] In some embodiments, the time of the catalytic hydrogenation reaction in step S100 is 5 - 6 h, such as 5.5 h, etc.

[0034] In some embodiments, the catalyst for the catalytic hydrogenation reaction is a ruthenium-carbon catalyst, which can be obtained from commercial channels, including but not limited to the Ru / C type catalyst produced by Shaanxi Rarechem New Materials Co., Ltd.

[0035] In some embodiments, the organic solvent includes at least one of isopropanol, n-butanol, and cyclohexane.

[0036] In some embodiments, the process of the catalytic hydrogenation reaction is as follows: Add wind turbine blades, organic solvent, and hydrogenation catalyst to a high-pressure reactor. Then replace the air in the high-pressure reactor with hydrogen, and then fill the high-pressure reactor with hydrogen. Slowly heat to the reaction temperature and carry out the reaction under stirring.

[0037] In some embodiments, the pyrolysis in step S200 is carried out in a pyrolysis furnace.

[0038] In some embodiments, the pyrolysis temperature in step S200 is 280 - 330 °C, such as 300 °C, etc.

[0039] In some embodiments, the pyrolysis atmosphere in step S200 is a mixed gas composed of nitrogen and oxygen, where the volume content of oxygen is 6 - 8%, such as 7%, etc.

[0040] In some embodiments, the pyrolysis time in step S200 is 3 - 4 h, such as 3.5 h, etc.

[0041] The following describes the wind turbine blade recycling method based on hydro-pyrolysis of the present application with specific embodiments.

[0042] I. Examples and Comparative Examples

[0043] Example 1

[0044] Add 1 Kg of wind turbine blades, 5000 mL of isopropanol, and 50 g of Ru / C type hydrogenation catalyst to a high-pressure reactor. After replacing the air in the high-pressure reactor with hydrogen, fill the high-pressure reactor with 4 MPa of hydrogen. Slowly heat the high-pressure reactor to 160 °C and then react for 5 h under stirring. The catalytic hydrogenation is completed. Put the hydrogenated blades into a pyrolysis furnace and pyrolyze for 3.6 h under a continuous nitrogen-oxygen mixed atmosphere (the volume content of oxygen in the mixed atmosphere is 7.2%) at 305 °C to complete the pyrolysis and obtain relatively pure glass fibers, realizing the recycling of the blades.

[0045] Examples 2 - 5 are basically the same as Example 1, except that the values of some relevant process parameters are different. Specifically, see Table 1.

[0046] The wind turbine blade recycling methods of Comparative Examples 1 - 2 are basically the same as Example 1, except that the wind turbine blades are directly pyrolyzed without hydrogenation treatment.

[0047] II. Effect Test

[0048] 1. Test Method for Recycled Fiber Performance

[0049] (1) Fiber Purity

[0050] The content of resin in recycled fiber is analyzed by a Mettler Toledo thermogravimetric analyzer. The lower the content, the more fully the resin in the blade is pyrolyzed, and the higher the fiber purity.

[0051] (2) Fiber Strength Retention Rate

[0052] The tensile strength of recycled fiber is measured by an LLY-06E tensile testing machine. The ratio of its strength to that of the original fiber represents the strength retention rate of the recycled fiber. The larger the retention rate, the smaller the damage to the recycled fiber during the pyrolysis process.

[0053] 2. Test Results

[0054] The performance of the reinforcing fibers obtained by the recycling methods of Examples 1-5 and Comparative Examples 1-2 is tested, and the test results are shown in Table 1.

[0055] Table 1 Relevant Process Parameters and Recycling Effects of Examples and Comparative Examples

[0056]

[0057] It can be seen from Table 1 that hydrogenation pretreatment of the blade can significantly improve the pyrolysis effect of the blade, that is, under the same pyrolysis temperature and pyrolysis time, the fiber purity and strength retention rate obtained by pyrolysis recycling after pretreatment are higher, indicating that the matrix resin in the blade can be fully pyrolyzed after hydrogenation pretreatment. In addition, the hydrogenation reaction medium also has a significant impact on the quality of the recycled fiber. After hydrogenation in isopropanol medium and then pyrolysis, the quality of the recycled fiber is significantly better than that of n-butanol and cyclohexane, probably because the hydrogenation conversion rate in isopropanol medium is higher than that in other media. In Comparative Examples 1-2, due to the lack of hydrogenation pretreatment, the resin is not fully pyrolyzed and adheres to the surface of the recycled fiber, resulting in lower strength and purity of the recycled fiber. At this time, the fiber strength retention rate actually represents the strength of the "fiber and its residual resin" mixture.

[0058] In this application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc., mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0059] Although the embodiments of this application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting this application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A method for recycling wind turbine blades based on hydrothermal pyrolysis, characterized in that, Comprising: Catalytic hydrogenation reaction is carried out on a wind power blade and an organic solvent in a hydrogen atmosphere under the action of a hydrogenation catalyst, and then catalytic pyrolysis is carried out to recover glass fiber; The temperature of the catalytic hydrogenation reaction is 150 - 160 °C; the time of the catalytic hydrogenation reaction is 5 - 6 h; the catalyst for the catalytic hydrogenation reaction is a ruthenium-carbon catalyst; the organic solvent is at least one of isopropanol, n-butanol, and cyclohexane; the pyrolysis atmosphere is a mixed gas composed of nitrogen and oxygen, and the pyrolysis temperature is 280 - 330 °C.

2. The recovery method according to claim 1, wherein The pressure of the catalytic hydrogenation reaction is 2.8 - 5.2 MPa.

3. The recovery method according to claim 1, wherein The mass ratio of the wind power blade, the organic solvent, and the hydrogenation catalyst is (16 - 24):(64 - 96):(0.8 - 1.2).

4. The recovery method according to claim 3, characterized in that The mass ratio of the wind power blade, the organic solvent, and the hydrogenation catalyst is 20:80:

1.

5. The recovery method according to claim 1, characterized in that, The process of the catalytic hydrogenation reaction is as follows: Add a wind power blade, an organic solvent, and a hydrogenation catalyst into a high-pressure reaction kettle, then displace the air in the high-pressure reaction kettle with hydrogen, and then fill the high-pressure reaction kettle with hydrogen, heat it to the reaction temperature, and carry out the reaction under stirring.

6. The recovery method according to claim 1, characterized in that, The volume content of oxygen in the pyrolysis atmosphere is 6 - 8%; And / or, the pyrolysis is carried out in a pyrolysis furnace.

7. The recovery method according to claim 1, characterized in that, The pyrolysis time is 3 - 4 h.

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