A method for recycling wind turbine blades based on a Lewis base-supercritical water system

Abstract

The present application discloses a method for recycling wind turbine blades based on a Lewis base-subcritical water system, comprising: dispersing a Lewis basic ionic liquid in water to obtain a reaction medium; reacting the wind turbine blades with the reaction medium under subcritical conditions, and then filtering to recover the fibers. The method for recycling wind turbine blades based on the Lewis base-subcritical water system of the present application uses a Lewis basic ionic liquid as a catalyst, which can rapidly degrade the matrix resin of the wind turbine blades in subcritical water, thereby recovering the reinforcing fibers. It has the advantages of short treatment time, high treatment efficiency, and high quality of the recovered fibers, and has broad application prospects in the field of recycling retired wind turbine blades.

Description

Technical Field

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

[0002] Retired wind turbine blades are a new type of industrial solid waste that has emerged in recent years. Their materials are mainly fiberglass, that is, glass fiber-reinforced epoxy resin composites, which are difficult to degrade and have high added value. If not properly treated, they will pollute the environment and cause waste of resources.

[0003] Currently, the main treatment method for retired wind turbine blades is landfill, but with the increasingly strict environmental protection policies, this method will be prohibited. Wet degradation is a method for recycling resin-based composites, which can treat wind turbine blades and recover the reinforcing fibers therein. However, this method usually needs to be carried out in a strong acid and strong base (protic acid, protic base) system, with high reaction temperature and long reaction time (more than ten hours), resulting in high energy consumption and low efficiency for recycling, great damage to the recycled fibers, and large corrosion to the equipment. Summary of the Invention

[0004] In view of this, this application aims to provide a method for recycling wind turbine blades based on a Lewis base-subcritical water system. Using Lewis (lewis) basic ionic liquid as a catalyst, the matrix resin of the wind turbine blades can be rapidly degraded in subcritical water, thereby recovering the reinforcing fibers, which has the advantages of short treatment time, high treatment efficiency, high quality of the recycled fibers, etc., and has broad application prospects in the field of recycling retired wind turbine blades.

[0005] To achieve the above object, an embodiment of this application provides a method for recycling wind turbine blades based on a Lewis base-subcritical water system, including:

[0006] Disperse a Lewis basic ionic liquid in water to obtain a reaction medium;

[0007] React the wind turbine blades with the reaction medium under subcritical conditions, and then filter to recover the fibers.

[0008] In some embodiments, the content of the ionic liquid in water is 0.5-1 wt%.

[0009] In some embodiments, the ionic liquid is 1-ethyl-3-methylimidazolium bromide or / and 1-ethyl-3-methylimidazolium chloride.

[0010] In some embodiments, the subcritical conditions are: temperature 300-350 °C, pressure 16-21 MPa.

[0011] In some embodiments, the reaction time is 20-30 min.

[0012] In some embodiments, the addition amount of the wind power blade is 10-20 wt% of the reaction medium.

[0013] In some embodiments, the recovery method further includes:

[0014] Before the reaction of the wind power blade and the reaction medium under subcritical conditions, the wind power blade after removing the metal components is cut into blocks.

[0015] In some embodiments, the length and width of the wind power blade cut into blocks do not exceed 5 cm.

[0016] In some embodiments, the reaction is carried out in a high-pressure reactor or a high-pressure tank.

[0017] In some embodiments, the wind power blade is a waste wind power blade.

[0018] The beneficial effects that can be brought by the wind power blade recovery method based on the Lewis base-subcritical water system in the embodiments of the present application are as follows:

[0019] (1) Subcritical water can degrade epoxy resin composites, but the degradation effect is poor. In the present application, a specific Lewis basic ionic liquid rather than a protonated strong base is used as a catalyst, which can greatly accelerate the degradation rate of epoxy resin in subcritical water, so that the degradation and recovery time of the wind power blade in the present application is significantly shorter than that of the traditional wet degradation, effectively reducing the degradation energy consumption and improving the recovery efficiency.

[0020] (2) In the present application, two non-toxic substances, ionic liquid and water, are selected as the reaction medium, which can prevent secondary pollution caused by wet degradation of the blade.

[0021] (3) The fibers recovered by the method of the present application have high quality, their purity can reach more than 97%, their mechanical properties are good, and their strength retention rate can reach more than 97% of the original fibers. The recovered fibers can be used for the manufacture of fiberglass paper or as raw materials for various glass devices.

[0022] (4) The recovery process is simple, the recovery efficiency is high, it is suitable for the treatment of various types of wind power blades, and has broad application prospects.

[0023] The additional aspects and advantages of the present application will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present application. Detailed Description of the Embodiments

[0024] The embodiments of the present application are described in detail below. The embodiments are exemplary and are intended to explain the present application, but should not be construed as limiting the present application.

[0025] 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.

[0026] 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.

[0027] The method for recycling wind turbine blades based on the Lewis base-supercritical water system according to the embodiments of the present application includes:

[0028] Disperse a Lewis basic ionic liquid in water to obtain a reaction medium;

[0029] React the wind turbine blade with the reaction medium under subcritical conditions, and then filter to recover the fibers.

[0030] The method for recycling wind turbine blades based on the Lewis base-supercritical water system according to the embodiments of the present application uses a Lewis basic ionic liquid as a catalyst, which can cause the matrix resin of the blade to rapidly degrade in supercritical water, thereby recovering the reinforcing fibers. Since a non-protic Lewis base is selected as the catalyst, the matrix resin of the wind turbine blade rapidly degrades in supercritical water (20 - 30 min), which is significantly shorter than the traditional wet degradation time (more than 10 h), effectively reducing the energy consumption for recycling, the damage to the recycled fibers, and the corrosion of the equipment, while greatly improving the recycling efficiency.

[0031] In some embodiments, the content of the ionic liquid in water is 0.5 - 1 wt%, including but not limited to 0.5 wt%, 0.7 wt%, 0.9 wt% or 1 wt%. If the content of the ionic liquid is too low, the catalytic effect is limited, and if the content is too high, the recycling cost will increase. The ionic liquid includes but is not limited to one or two of 1-ethyl-3-methylimidazolium bromide and 1-ethyl-3-methylimidazolium chloride, which can cause the matrix resin of the wind turbine blade to rapidly degrade in supercritical water.

[0032] In this application, the reaction is carried out under subcritical conditions to keep water in a subcritical state and, under the action of Lewis basic ionic liquid, greatly accelerate the degradation rate of epoxy resin in subcritical water. Therefore, in some embodiments, the subcritical conditions are: temperature 300 - 350 °C, pressure 16 - 21 MPa. Among them, the temperature includes but is not limited to 300 °C, 310 °C, 320 °C, 330 °C, 340 °C or 350 °C; the pressure includes but is not limited to 16 MPa, 18 MPa, 20 MPa or 21 Pa. When the temperature and pressure are within the above ranges, subcritical water can be produced. It should be noted here that the subcritical conditions are also the reaction conditions of this application. In addition, considering the thermal stability of the ionic liquid, if the reaction temperature is too high, the ionic liquid is likely to decompose and lose its catalytic activity.

[0033] In some embodiments, the reaction time is 20 - 30 min, including but not limited to 20 min, 24 min, 28 min or 30 min.

[0034] In some embodiments, the addition amount of the wind turbine blade is 10 - 20 wt% of the reaction medium.

[0035] In some embodiments, the recovery method of this application further includes: before the reaction of the wind turbine blade and the reaction medium under subcritical conditions, cutting the wind turbine blade after removing the metal components into blocks. Removing the metal components from the wind turbine blade can avoid side reactions that may be brought about by the participation of metal in the reaction, and cutting the wind turbine blade into blocks can increase the reaction contact area, improve the reaction rate, and at the same time facilitate putting the wind turbine blade into the reaction device. In some embodiments, the length and width of the wind turbine blade cut into blocks do not exceed 5 cm. In some embodiments, the reaction is carried out in a high-pressure reactor or a high-pressure tank.

[0036] In some embodiments, the wind turbine blade is a waste wind turbine blade.

[0037] The following further illustrates the wind turbine blade recovery method based on the Lewis base - subcritical water system of this application with specific embodiments.

[0038] I. Examples and Comparative Examples

[0039] Example 1

[0040] The wind turbine blade recovery method based on the Lewis base - subcritical water system in this example includes the following steps:

[0041] (1) Cutting the waste wind turbine blade after removing the metal components into blocks (length ≤ 5 cm, width ≤ 5 cm);

[0042] (2) Disperse 1-ethyl-3-methylimidazolium bromide in water to prepare a reaction medium; the content of 1-ethyl-3-methylimidazolium bromide in water is 0.75 wt%.

[0043] (3) Place 1000 ml of the reaction medium in a high-pressure reactor, then add 500 g of wind power blades cut into blocks, stir and react at 325 °C and 20 MPa for 25 min, and then filter to recover the fibers.

[0044] The recovery methods of Examples 2-6 and Comparative Example 1 are basically the same as those of Example 1, except that: the values of the process parameters in each example are different from those of Example 1; in Comparative Example 1, no Lewis basic ionic liquid is added, and the values of some process parameters are different from those of Example 1. For the specific values of the process parameters of the recovery methods of Examples 2-6 and Comparative Example 1, please refer to Table 1.

[0045] II. Effect test

[0046] The recovery effect of the recovery method is evaluated by the resin residue rate and the fiber strength retention rate of the recovered fibers.

[0047] 1. Test method for the performance of recovered fibers

[0048] (1) Fiber purity

[0049] Use a Mettler Toledo thermogravimetric analyzer to analyze the resin content in the recovered fibers. The lower the content, the more fully the resin in the blades is degraded.

[0050] (2) Fiber strength retention rate

[0051] Use an LLY-06E tensile testing machine to measure the tensile strength of the recovered fibers. The ratio of it to the strength of the original fibers represents the fiber strength retention rate. The larger the retention rate, the smaller the impact of the degradation process on the recovered fibers.

[0052] 2. Test results

[0053] Test the recovery effects of the recovery methods of Examples 1-6 and Comparative Example 1. The test results are shown in Table 1.

[0054] Table 1 Relevant reaction conditions and recovery effects of examples and comparative examples

[0055]

[0056] As can be seen from Table 1, in this application, if Lewis basic ionic liquid is not used as a catalyst and only subcritical water is used under the same degradation temperature and degradation time, only a small amount of resin degrades, indicating that the ionic liquid disclosed in this application has a significant promoting effect on the degradation of the matrix resin of wind power blades in subcritical water.

[0057] In this application, terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" 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.

[0058] 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 a Lewis base-supercritical water system, characterized in that, Comprising: Disperse a Lewis basic ionic liquid in water to obtain a reaction medium; React a wind power blade with the reaction medium under subcritical conditions, and then filter to recover the fibers; The content of the ionic liquid in water is 0.5 - 1 wt%; The ionic liquid is 1-ethyl-3-methylimidazolium bromide or / and 1-ethyl-3-methylimidazolium chloride; The subcritical conditions are: temperature 300 - 350 °C, pressure 16 - 21 MPa.

2. The recycling method according to claim 1, characterized in that, The reaction time is 20 - 30 min.

3. The recycling method according to claim 1, characterized in that, The addition amount of the wind power blade is 10 - 20 wt% of the reaction medium.

4. The recycling method according to claim 1, characterized in that, Also comprising: Before reacting the wind power blade with the reaction medium under subcritical conditions, cut the wind power blade after removing the metal components into blocks.

5. The recycling method according to claim 4, characterized in that, The length and width of the wind power blade cut into blocks do not exceed 5 cm.

6. The recycling method according to claim 1, characterized in that, The reaction is carried out in a high-pressure reactor or a high-pressure tank.

7. The recycling method according to claim 1, characterized in that, The wind power blade is a waste wind power blade.

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