WO2024082420A1 - Wind turbine blade recycling method based on repeated carbonization-oxidation - Google Patents

Abstract

A wind turbine blade recycling method based on repeated carbonization-oxidation, comprising: removing metal components from waste wind turbine blades, and then sequentially and alternately carrying out carbonization reaction and oxidation reaction for at least three times to obtain pure reinforced fibers, wherein the carbonization reaction is carried out in an inert atmosphere, and the oxidation reaction is carried out in an oxidizing atmosphere.

Description

A wind turbine blade recycling method based on repeated carbonization-oxidation

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on the Chinese patent application with application number 202211289532.2 and application date October 20, 2022, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby introduced into this application as a reference.

Technical Field

The present disclosure relates to the technical field of solid waste treatment, and in particular to a wind turbine blade recycling method based on repeated carbonization-oxidation.

Background technique

With the vigorous development of domestic wind power industry, the number of waste wind turbine blades is increasing, and it has become a new type of industrial solid waste that needs to be treated urgently. Wind turbine blades are mainly fiber-reinforced resin-based composite materials, which are difficult to degrade after retirement and have high added value. At present, there is no industrialized wind turbine blade recycling technology. Pyrolysis is a common composite material recycling method. It usually converts the matrix resin of the composite material into gaseous small molecule compounds under a specific atmosphere and high temperature (≥850℃) to recover the reinforcing fibers with higher added value to achieve resource utilization. This method has the technical advantages of simple process, easy scalability and engineering in the treatment of waste blades, but it has disadvantages such as high energy consumption, low efficiency, and poor quality of recycled fibers. Therefore, it is of great significance to develop a low-energy wind turbine blade recycling method.

Summary of the invention

In view of this, an object of the present disclosure is to provide a wind turbine blade recycling method based on repeated carbonization-oxidation.

To achieve the above-mentioned purpose, the embodiment of the present disclosure proposes a wind turbine blade recycling method based on repeated carbonization-oxidation, comprising:

After removing the metal components from the waste wind turbine blades, the waste wind turbine blades are subjected to carbonization reaction and oxidation reaction alternately for at least three times to obtain pure reinforcing fibers;

The carbonization reaction is carried out in an inert atmosphere, and the oxidation reaction is carried out in an oxidizing atmosphere.

In some embodiments of the present disclosure, the carbonization reaction is carried out in a pyrolysis carbonization furnace, and the oxidation reaction is carried out in an oxidation furnace.

In some embodiments of the present disclosure, the temperature of each carbonization reaction is 280-320°C.

In some embodiments of the present disclosure, each carbonization reaction lasts for 10-15 minutes.

In some embodiments of the present disclosure, the inert atmosphere is one or more of nitrogen, argon and helium.

In some embodiments of the present disclosure, the temperature of each oxidation reaction is 400-420°C.

In some embodiments of the present disclosure, the duration of each oxidation reaction is 10-15 minutes.

In some embodiments of the present disclosure, the oxidizing atmosphere is a mixed gas of nitrogen and oxygen, wherein the volume content of oxygen is 12-15%.

In some embodiments of the present disclosure, after removing the metal components from the waste wind turbine blades, the carbonization reaction and the oxidation reaction are alternately performed three times.

Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention.

Detailed ways

The embodiments of the present disclosure are described in detail below, which are intended to explain the present disclosure but should not be construed as limiting the present disclosure.

Unless otherwise specified, the raw materials and equipment involved in the embodiments of the present disclosure can be obtained through commercial channels or prepared or processed according to known methods; the methods involved in the embodiments of the present disclosure are all conventional methods unless otherwise specified.

The applicant found that the microstructure of wind turbine blades is complex, with sandwich and multi-layer reinforced fiber layers. In the traditional pyrolysis method for recycling wind turbine blades, the carbonization and oxidation processes are combined. Carbonization carbonizes the resin in the wind turbine blades, and oxidation oxidizes the carbonized products into small gas molecules such as carbon dioxide. The penetration of oxygen in the oxidation process directly affects the entire oxidation process, oxidation time and oxidation efficiency, which in turn affects the purity of the fiber. When wind turbine blades are recycled by traditional pyrolysis, a dense pyrolytic carbon layer (such as a carbon layer with a thickness of 1 cm) is easily formed between the fiber surface and the fiber layer, preventing oxygen penetration, seriously affecting the oxidation efficiency and the purity of the recycled fiber. How to timely remove the dense carbon layer formed in the carbonization process and ensure the effective penetration of oxygen is the key to improving the oxidation efficiency and the purity of the recycled fiber. Therefore, the embodiments of the present disclosure propose a wind turbine blade recycling method based on repeated carbonization-oxidation, which divides the carbonization and oxidation processes in the traditional pyrolysis method into multiple times. The wind turbine blades are repeatedly carbonized-oxidized in different atmospheres. Each time carbonization is performed, oxidation is immediately performed, and the carbon layer formed by carbonization is promptly oxidized into gas and removed. In this way, the repeated carbonization-oxidation process is equivalent to peeling off the resin on the fiber surface layer by layer, which can not only improve the oxygen permeability, thereby improving the oxidation efficiency, but also improve the fiber purity.

The wind turbine blade recycling method based on repeated carbonization-oxidation of the embodiment of the present disclosure includes:

After removing the metal components from the waste wind turbine blades, the waste wind turbine blades are subjected to carbonization reaction and oxidation reaction alternately for at least three times to obtain pure reinforcing fibers;

The carbonization reaction is carried out in an inert atmosphere, and the oxidation reaction is carried out in an oxidizing atmosphere.

The wind turbine blade recycling method based on repeated carbonization-oxidation of the disclosed embodiment separates the carbonization and oxidation processes in the traditional pyrolysis method by adjusting the reaction atmosphere, which can reduce the pyrolysis temperature to the greatest extent, thereby reducing the overall blade recovery energy consumption and improving the quality of the recovered fiber. At the same time, repeated carbonization-oxidation processes can effectively prevent the formation of a dense carbon layer, improve oxidation efficiency, and thus improve blade recovery efficiency, while also reducing thermal damage to the fiber and improving the recovery value.

In some embodiments, in order to improve the carbonization and oxidation efficiency, before the first carbonization of the scrap wind turbine blades after removing the metal components, the scrap wind turbine blades with the metal components removed are cut into blocks, and the total flow rate of the oxidizing atmosphere is ensured, for example, when cut into blocks of length × width = 10 cm × 10 cm, the total flow rate of the oxidizing atmosphere is 10-20 L/min, preferably 15 L/min.

In some embodiments, the carbonization reaction and the oxidation reaction only need to be carried out separately, and the present disclosure does not limit the locations where the carbonization reaction and the oxidation reaction occur. As a possible example, the carbonization reaction is carried out in a pyrolysis carbonization furnace, and the oxidation reaction is carried out in an oxidation furnace.

In the present disclosure, in order to facilitate engineering implementation, in each carbonization-oxidation cycle, the reaction atmosphere of carbonization and oxidation is fixed, and the reaction temperature corresponds to the reaction time. Once the reaction temperature is fixed, the reaction time is also fixed.

In some embodiments, the temperature of each carbonization reaction is 280-320°C. If the temperature is lower than 280°C, the carbonization speed is too slow or even cannot be achieved; if the temperature is higher than 320°C, the oxidation speed is accelerated and the carbonization and oxidation processes cannot be effectively separated. Preferably, the temperature of each carbonization reaction is 300°C.

In some embodiments, each carbonization reaction lasts for 10-15 minutes; preferably, each carbonization reaction lasts for 12 minutes.

In some embodiments, the inert atmosphere is one or more of nitrogen, argon and helium, preferably nitrogen.

In some embodiments, the temperature of each oxidation reaction is 400-420°C, preferably 410°C.

In some embodiments, the duration of each oxidation reaction is 10-15 min, preferably 12 min.

In some embodiments, the oxidizing atmosphere is a mixed gas of nitrogen and oxygen, wherein the volume content of oxygen is 12-15%, preferably 13%.

In the present disclosure, the number of times the carbonization reaction and the oxidation reaction are alternately performed after the metal components of the waste wind turbine blades are removed is not limited, as long as pure reinforcing fibers can be obtained. As a possible example, the number of times the carbonization reaction and the oxidation reaction are alternately performed after the metal components of the waste wind turbine blades are removed is 3 times. At this time, the wind turbine blade recycling method based on repeated carbonization-oxidation in the embodiment of the present disclosure includes the following steps S1 to S6.

S1: removing metal components from waste wind turbine blades and cutting them into blocks, performing a first carbonization reaction in a first inert gas atmosphere to obtain a first carbonization product;

S2: subjecting the first carbonized product to a first oxidation reaction in a first oxidizing atmosphere to obtain a first oxidation product;

S3: subjecting the first oxidation product to a second carbonization reaction in a second inert atmosphere to obtain a second carbide;

S4: subjecting the second carbide to a second oxidation reaction in a second oxidation atmosphere to obtain a second oxidation product;

S5: subjecting the second oxidation product to a third carbonization reaction in a third inert atmosphere to obtain a third carbide;

S6: subjecting the third carbide to a third oxidation reaction in a third oxidation atmosphere to obtain pure reinforcing fibers.

Among them, the first inert atmosphere, the second inert atmosphere and the third inert atmosphere are one or more of nitrogen, argon and helium, preferably nitrogen; the first oxidizing atmosphere, the second oxidizing atmosphere and the third oxidizing atmosphere are all mixed gases of nitrogen and oxygen, wherein the volume content of oxygen is 12-15%, preferably 13%; the flow rates of the first oxidizing atmosphere, the second oxidizing atmosphere and the third oxidizing atmosphere are all 10-20L/min, preferably 15L/min; the temperatures of the first carbonization reaction, the second carbonization reaction and the third carbonization reaction are all 280-320°C, preferably 300°C; the temperatures of the first oxidation reaction, the second oxidation reaction and the third oxidation reaction are all 400-420°C, preferably 410°C; the reaction times of the first carbonization reaction, the second carbonization reaction and the third carbonization reaction, the first oxidation reaction, the second oxidation reaction and the third oxidation reaction are all 10-15min, preferably 12min.

The wind turbine blade recycling method based on repeated carbonization-oxidation disclosed in the present invention is described below with reference to specific embodiments.

1. Implementation

Example 1

After removing the metal components from the waste wind turbine blades, cut them into blocks (length × width = 10 cm × 10 cm), put them into a pyrolysis carbonization furnace, and carry out the first carbonization reaction at 300 ° C for 12 minutes under a nitrogen atmosphere to obtain a first carbonization product. Then the first carbonization product is transferred to an oxidation furnace, and in a mixed gas atmosphere of nitrogen and oxygen with an oxygen volume content of 13% (total gas flow rate of 15 L/min), the first oxidation reaction is carried out at 410 ° C for 12 minutes to obtain a first oxidation product. Then the first oxidation product is placed in a pyrolysis carbonization furnace, and in a nitrogen atmosphere, the second carbonization reaction is carried out at 300 ° C for 12 minutes to obtain a second carbonization product. The second carbonization product is then transferred to an oxidation furnace, and in a mixed gas atmosphere of nitrogen and oxygen with an oxygen volume content of 13% (total gas flow rate of 15 L/min), the second oxidation reaction is carried out at 410 ° C for 12 minutes to obtain a second oxidation product. Then, the second oxidation product was placed in a pyrolysis carbonization furnace, and a third carbonization reaction was carried out at 300°C for 12 minutes under a nitrogen atmosphere to obtain a third carbonization product. Finally, the third carbonization product was transferred to an oxidation furnace, and a third oxidation reaction was carried out at 410°C for 12 minutes in a mixed gas atmosphere of nitrogen and oxygen with an oxygen volume content of 13% (total gas flow rate of 15L/min) to obtain pure reinforcing fibers and realize blade recovery.

Examples 2-7 are basically the same as Example 1, except that some process parameters are different.

The relevant process parameters of Examples 2-7 are shown in Table 1.

Table 1 Relevant process parameters of Examples 2-7

2. Effect Test

1. Glass fiber performance test method

(1) Fiber purity

The resin content in the glass fiber obtained after pyrolysis was analyzed using a Mettler Toledo thermogravimetric analyzer. The lower the content, the more complete the pyrolysis of the resin in the blade and the higher the fiber purity.

(2) Fiber strength retention rate

The tensile strength of the glass fiber obtained after pyrolysis was measured using an LLY-06E tensile testing machine. The ratio of the tensile strength of the glass fiber obtained after pyrolysis to the strength of the original fiber represents the strength retention rate of the glass fiber obtained after pyrolysis. The greater the retention rate, the less damage the pyrolysis process causes to the glass fiber.

2. Test results

The fiber purity and fiber strength retention rate of the reinforcing fibers obtained by the recycling methods of Examples 1-7 were tested, and the test results are shown in Table 2.

Table 2 Recovery effect of Examples 1-7

project	Fiber purity/%	Fiber strength retention rate/%
Example 1	96	99
Example 2	99	92
Example 3	94	96
Example 4	95	97
Example 5	93	96
Example 6	94.8	95.1
Example 7	98	92.5

It can be seen from Table 2 that the recycling method of repeated carbonization-oxidation disclosed in the present invention can obtain high-quality recycled fibers at a lower pyrolysis temperature and a shorter pyrolysis time.

The wind turbine blade recycling method based on repeated carbonization-oxidation of the disclosed embodiment, on the one hand, separates the carbonization and oxidation processes in the traditional pyrolysis method by regulating the reaction atmosphere, and sets a special atmosphere and reaction temperature for different reaction stages to minimize the pyrolysis temperature, thereby reducing the overall blade recycling energy consumption and improving the quality of the recycled fiber; on the other hand, due to the complex microstructure of the wind turbine blade, the presence of sandwich and multi-layer reinforced fiber layers, during the carbonization process, a dense pyrolytic carbon layer is easily formed between the fiber surface and the fiber layer, preventing oxygen penetration, seriously affecting the oxidation efficiency and the purity of the recycled fiber. The disclosed method repeatedly carries out the carbonization-oxidation process, which can effectively prevent the formation of a dense carbon layer, improve the oxidation efficiency, and thus improve the blade recovery efficiency, while also reducing the thermal damage to the fiber and improving the recovery value.

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

Although the embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are illustrative and are not to be construed as limitations of the present disclosure. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present disclosure.

Claims (9)

1. A wind turbine blade recycling method based on repeated carbonization-oxidation, comprising:

   After removing the metal components from the waste wind turbine blades, the waste wind turbine blades are subjected to carbonization reaction and oxidation reaction alternately for at least three times to obtain pure reinforcing fibers;

   The carbonization reaction is carried out in an inert atmosphere, and the oxidation reaction is carried out in an oxidizing atmosphere.
2. According to the wind turbine blade recycling method based on repeated carbonization-oxidation according to claim 1, the carbonization reaction is carried out in a pyrolysis carbonization furnace, and the oxidation reaction is carried out in an oxidation furnace.
3. According to the wind turbine blade recycling method based on repeated carbonization-oxidation according to claim 1, the temperature of each carbonization reaction is 280-320°C.
4. According to the wind turbine blade recycling method based on repeated carbonization-oxidation according to claim 1, wherein the carbonization reaction time for each time is 10-15 minutes.
5. According to the wind turbine blade recycling method based on repeated carbonization-oxidation according to claim 1, wherein the inert atmosphere is one or more of nitrogen, argon and helium.
6. According to the wind turbine blade recycling method based on repeated carbonization-oxidation according to claim 1, the temperature of each oxidation reaction is 400-420°C.
7. According to the wind turbine blade recycling method based on repeated carbonization-oxidation according to claim 1, wherein the time of each oxidation reaction is 10-15 minutes.
8. According to the wind turbine blade recycling method based on repeated carbonization-oxidation according to claim 1, wherein the oxidizing atmosphere is a mixed gas of nitrogen and oxygen, wherein the volume content of oxygen is 12-15%.
9. According to the wind turbine blade recycling method based on repeated carbonization-oxidation according to claim 1, the number of times the carbonization reaction and the oxidation reaction are alternately performed in sequence after the metal components of the waste wind turbine blades are removed is 3 times.