A low-carbon wind turbine blade recycling system and method

Abstract

The present invention discloses a low-carbon wind turbine blade recycling system and method. The low-carbon wind turbine blade recycling method includes: under a pyrolysis atmosphere, removing metal components from waste wind turbine blades and then performing pyrolysis to obtain glass fibers; exchanging heat between the pyrolysis tail gas and the pyrolysis atmosphere to obtain the pyrolysis tail gas after heat exchange; reacting the pyrolysis tail gas after heat exchange with hydrogen under the action of a catalyst, and converting carbon dioxide in the pyrolysis tail gas after heat exchange into methane. The low-carbon wind turbine blade recycling method of the present invention can obtain relatively pure glass fibers. At the same time, heat is recovered by exchanging heat between the pyrolysis tail gas and the pyrolysis atmosphere, and carbon dioxide in the pyrolysis tail gas is converted into methane under the conditions of the participation of hydrogen and a catalyst, which not only realizes waste heat recovery, reduces the energy consumption of blade recycling, but also reduces carbon emissions in the process of waste blade recycling and improves the resource recycling value of blades.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste treatment, and particularly relates to a low-carbon wind turbine blade recycling system and method. Background Art

[0002] Waste wind turbine blades are a type of high-value industrial solid waste that appears during the development of new energy. At present, the main treatment method for waste blades is landfill, but with the increasingly strict environmental protection policies, this method will be prohibited. Pyrolysis is a new method for recycling resin-based composites. Usually, under specific atmosphere and high temperature (≥850 °C), the matrix resin of the composite material is converted into gases such as carbon dioxide and a small amount of pyrolytic carbon, and the high-value reinforcing fibers are recovered to achieve resource utilization. The main material of wind turbine blades is glass fiber-reinforced epoxy resin composite material. Therefore, this method can be used for the recycling of wind turbine blades, and has the characteristics of simple process and easy scale-up, with broad application prospects. However, the pyrolysis tail gas is mainly carbon dioxide, which belongs to a high-carbon emission technology and violates the current policies for controlling carbon emissions. Therefore, developing a low-carbon pyrolysis technology is of great significance for the recycling of waste wind turbine blades. Summary of the Invention

[0003] In view of this, an object of the present invention is to provide a low-carbon wind turbine blade recycling method, in which the waste wind turbine blade is pyrolyzed after removing the metal components to obtain relatively pure glass fibers. At the same time, the pyrolysis tail gas is heat-exchanged with the pyrolysis atmosphere, and the carbon dioxide in the pyrolysis tail gas is converted into methane under the participation of hydrogen and a catalyst, which not only realizes waste heat recovery, reduces the energy consumption of blade recycling, but also reduces the carbon emissions during the recycling process of waste blades and improves the resource recycling value of the blades.

[0004] Another object of the present invention is to provide a low-carbon wind turbine blade recycling system.

[0005] To achieve the above object, the first aspect embodiment of the present invention proposes a low-carbon wind turbine blade recycling method, including pyrolyzing the waste wind turbine blade after removing the metal components in a pyrolysis atmosphere to obtain glass fibers;

[0006] Heat-exchanging the pyrolysis tail gas with the pyrolysis atmosphere to obtain the heat-exchanged pyrolysis tail gas;

[0007] Reacting the heat-exchanged pyrolysis tail gas with hydrogen under the action of a catalyst, and converting the carbon dioxide in the heat-exchanged pyrolysis tail gas into methane.

[0008] In some embodiments of the present invention, the pyrolysis atmosphere is a mixed gas composed of nitrogen and oxygen, and the volume content of oxygen is between 4-6%.

[0009] In some embodiments of the present invention, the pyrolysis is carried out in a pyrolysis furnace; the pyrolysis atmosphere continuously passes through the pyrolysis furnace, and the flow rate is 10-20 L / min; the temperature of the pyrolysis atmosphere entering the pyrolysis furnace is 730-760 °C.

[0010] In some embodiments of the present invention, the pyrolysis temperature is 850-900 °C, and the pyrolysis time is 2-3 h.

[0011] In some embodiments of the present invention, the temperature of the pyrolysis tail gas after heat exchange is 150-170 °C;

[0012] The reaction temperature of the pyrolysis tail gas after heat exchange and hydrogen is 150-170 °C.

[0013] In some embodiments of the present invention, the molar ratio of hydrogen to carbon dioxide in the pyrolysis tail gas after heat exchange is between 4:1 and 9:2.

[0014] In some embodiments of the present invention, the catalyst is ruthenium-modified titanium dioxide powder, and the mass fraction of ruthenium is 0.8-1%.

[0015] In some embodiments of the present invention, the preparation method of the ruthenium-modified titanium dioxide powder is as follows: impregnate the nano-titanium dioxide powder in a theoretical amount of soluble ruthenium salt solution, then dry it at 80-120 °C for 6-10 h, and then calcine it at 400-600 °C for 6-10 h.

[0016] To achieve the above object, a second aspect embodiment of the present invention proposes a low-carbon wind turbine blade recycling system, including a pyrolysis furnace, the pyrolysis furnace having an inlet for waste wind turbine blades, a tail gas outlet, and a pyrolysis atmosphere inlet;

[0017] A heat exchanger, the hot side inlet of the heat exchanger is connected to the tail gas outlet, the cold side inlet of the heat exchanger is connected to the outlet of the pyrolysis atmosphere source, and the cold side outlet of the heat exchanger is connected to the pyrolysis atmosphere inlet;

[0018] A reactor, the reactor having a first inlet and a second inlet, the first inlet is connected to the hot side outlet of the heat exchanger, and the second inlet is connected to the hydrogen source.

[0019] In some embodiments of the present invention, the reactor is a packed tower; the heat exchanger is a tubular heat exchanger or a plate heat exchanger.

[0020] The low-carbon wind turbine blade recycling method of the embodiments of the present invention has the following beneficial effects:

[0021] (1) In the blade recycling process, the pyrolysis tail gas reacts with hydrogen under the action of a catalyst, converting carbon dioxide in the tail gas into methane, which can be recycled as fuel. This not only reduces carbon emissions during the recycling process of waste blades but also improves the resource recycling value of the blades.

[0022] (2) In the blade recycling process, part of the heat of the tail gas is recovered and used to heat the pyrolysis atmosphere, realizing waste heat utilization and reducing the energy consumption of blade recycling.

[0023] (3) Using ruthenium-modified titanium dioxide powder as a catalyst can achieve efficient conversion of carbon dioxide. Moreover, the conversion process utilizes the waste heat of the tail gas without additional heating, with low conversion energy consumption. All the equipment used is traditional industrial equipment, which is easy to engineer.

[0024] The beneficial effects of the low-carbon wind turbine blade recycling system in the embodiments of the present invention are basically the same as those of the low-carbon wind turbine blade recycling method in the embodiments of the present invention, and will not be elaborated here.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the drawings, wherein:

[0027] Figure 1 is a flowchart of a low-carbon wind turbine blade recycling method according to an embodiment of the present invention (also a simple structural schematic diagram of a low-carbon wind turbine blade recycling system according to an embodiment of the present invention)

[0028] Reference numerals:

[0029] 1 - Pyrolysis furnace; 2 - Heat exchanger; 3 - Reactor. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The embodiments of the present invention will be described in detail below, and the examples thereof are shown in the drawings. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0031] The raw materials and equipment in the embodiments of the present invention, unless otherwise specified, can be obtained through commercial channels or prepared or processed by known methods.

[0032] The low-carbon wind turbine blade recycling method and the low-carbon wind turbine blade recycling system of the embodiments of the present invention will be described below with reference to the drawings.

[0033] Figure 1Flow chart of a low-carbon wind turbine blade recycling method according to an embodiment of the present invention.

[0034] As Figure 1 shown, the low-carbon wind turbine blade recycling method of the embodiment of the present invention includes

[0035] Under a pyrolysis atmosphere, after removing the metal components from the waste wind turbine blade, pyrolysis is carried out to obtain relatively pure glass fiber;

[0036] The pyrolysis tail gas is heat-exchanged with the pyrolysis atmosphere to obtain the heat-exchanged pyrolysis tail gas;

[0037] The heat-exchanged pyrolysis tail gas reacts with hydrogen under the action of a catalyst, and carbon dioxide in the heat-exchanged pyrolysis tail gas is converted into methane.

[0038] The low-carbon wind turbine blade recycling method of the embodiment of the present invention removes the metal structure of the waste wind turbine blade and then pyrolyzes it to obtain relatively pure glass fiber. At the same time, the pyrolysis tail gas is heat-exchanged with the pyrolysis atmosphere, and carbon dioxide in the pyrolysis tail gas is converted into methane under the participation of hydrogen and a catalyst, which not only realizes waste heat recovery, reduces the energy consumption of blade recycling, but also reduces the carbon emissions in the process of waste blade recycling and improves the resource recycling value of the blade.

[0039] It should be noted that in actual operation, the pyrolysis atmosphere is the pyrolysis atmosphere at room temperature, which needs to be heat-exchanged with the pyrolysis tail gas first and then participate in the pyrolysis of the waste blade after preheating.

[0040] As a possible example, pyrolysis is carried out in a pyrolysis furnace; the temperature of the pyrolysis atmosphere entering the pyrolysis furnace is 730 - 760 °C, and the pyrolysis atmosphere continuously passes through the pyrolysis furnace. It should be noted that the total flow rate of the pyrolysis atmosphere is related to the size of the processed blade. For example, when processing a sample with a length × width = 10 cm × 10 cm, the total flow rate of the pyrolysis atmosphere is 10 - 20 L / min, preferably 15 L / min.

[0041] In some embodiments, the pyrolysis atmosphere is a mixed gas composed of nitrogen and oxygen, and the volume content of oxygen is between 4 - 6%, preferably 5%. The reason for choosing the mixed gas composed of nitrogen and oxygen as the pyrolysis atmosphere is to ensure efficient and sufficient pyrolysis of the blade. If the volume content of oxygen is controlled below 4%, the blade mainly undergoes carbonization to form a mixture of pyrolytic carbon and reinforcing fibers; if it is higher than 6%, the pyrolysis is too intense and even combustion occurs, resulting in great thermal damage to the recycled fibers.

[0042] In some embodiments, the pyrolysis temperature is 850 - 900 °C, preferably 875 °C; the pyrolysis time is 2 - 3 h, preferably 2.5 h.

[0043] In some embodiments, the temperature of the pyrolysis tail gas after heat exchange is 150 - 170 °C, preferably 160 °C; the reaction temperature of the pyrolysis tail gas after heat exchange and hydrogen is 150 - 170 °C, preferably 160 °C. It should be noted that in the present invention, the pyrolysis tail gas and hydrogen are in contact reaction, and the reaction time is very short, generally 2 - 3 s.

[0044] In some embodiments, the molar ratio of hydrogen to carbon dioxide in the pyrolysis tail gas after heat exchange is between 4:1 and 9:2, preferably 13:3.

[0045] In some embodiments, the catalyst is ruthenium-modified titanium dioxide powder, where the mass fraction of ruthenium is 0.8 - 1%, preferably 0.9%.

[0046] In some embodiments, the preparation method of ruthenium-modified titanium dioxide powder is as follows: Immerse the nano-titanium dioxide powder in a theoretical amount of soluble ruthenium salt solution, then dry it at 80 - 120 °C for 6 - 10 h, and then calcine it at 400 - 600 °C for 6 - 10 h. It should be noted that the soluble ruthenium salt here is the precursor, and ruthenium chloride, ruthenium nitrate, ruthenium acetate, etc. can be selected.

[0047] In some embodiments, in order to improve the pyrolysis efficiency, after removing the metal components from the waste wind turbine blade, it is cut into blocks and then pyrolyzed, for example, cut into blocks with a length × width = 10 cm × 10 cm.

[0048] The implementation system of the low-carbon waste wind turbine blade recycling method of the embodiments of the present invention is not limited. As a possible example, as Figure 1 shown, the recycling system of the low-carbon waste wind turbine blade includes a pyrolysis furnace 1, a heat exchanger 2, and a reactor 3; the pyrolysis furnace 1 has an inlet for waste wind turbine blades, a tail gas outlet, and a pyrolysis atmosphere inlet; the hot side inlet of the heat exchanger is connected to the tail gas outlet, the cold side inlet of the heat exchanger is connected to the outlet of the pyrolysis atmosphere source, the cold side outlet of the heat exchanger is connected to the pyrolysis atmosphere inlet, and the reactor 3 has a first inlet and a second inlet, the first inlet is connected to the hot side outlet of the heat exchanger, and the second inlet is connected to the hydrogen source.

[0049] In some embodiments, the reactor 3 is a packed tower, and the above catalyst can be used as the packing.

[0050] In some embodiments, the heat exchanger 2 can be a tubular heat exchanger, such as a shell-and-tube heat exchanger (such as a fixed tube sheet heat exchanger, etc.), a double-pipe heat exchanger, and a finned-tube heat exchanger, etc.

[0051] In some embodiments, the hot-side inlet of the heat exchanger is connected to the tail gas outlet through the first pipeline, the cold-side inlet of the heat exchange is connected to the outlet of the pyrolysis atmosphere source through the second pipeline, the cold-side outlet of the heat exchanger is connected to the pyrolysis atmosphere inlet through the third pipeline, the reactor 3 has a first inlet and a second inlet, the first inlet is connected to the hot-side outlet of the heat exchanger through the fourth pipeline, and the second inlet is connected to the hydrogen source through the fifth pipeline. Optionally, valves can be installed on each pipeline as needed to control the flow of materials.

[0052] The working process of the low-carbon wind turbine blade recycling system according to the embodiments of the present invention is as follows:

[0053] The pyrolysis atmosphere with the waste heat of the heat exchanger 2 and the waste wind turbine blades from which the metal components are removed enter the pyrolysis furnace 1. The pyrolysis tail gas generated after the pyrolysis of the waste wind turbine blades exchanges heat with the pyrolysis tail gas at room temperature to preheat the pyrolysis tail gas. The cooled pyrolysis tail gas enters the reactor 3, and carbon dioxide in the pyrolysis tail gas reacts with hydrogen under the action of a catalyst to generate methane.

[0054] The following specifically describes the low-carbon wind turbine blade recycling system and method according to the embodiments of the present invention with reference to specific embodiments.

[0055] I. Embodiment

[0056] Embodiment 1

[0057] As Figure 1 shown, the low-carbon wind turbine blade recycling system of this embodiment includes a pyrolysis furnace 1, a heat exchanger 2, and a reactor 3; the pyrolysis furnace 1 has an inlet for waste wind turbine blades, a tail gas outlet, and a pyrolysis atmosphere inlet; the hot-side inlet of the heat exchanger is connected to the tail gas outlet through the first pipeline, the cold-side inlet of the heat exchange is connected to the outlet of the pyrolysis atmosphere source through the second pipeline, the cold-side outlet of the heat exchanger is connected to the pyrolysis atmosphere inlet through the third pipeline, the reactor 3 has a first inlet and a second inlet, the first inlet is connected to the hot-side outlet of the heat exchanger through the fourth pipeline, and the second inlet is connected to the hydrogen source through the fifth pipeline.

[0058] The reactor is a packed tower, and its packing is ruthenium-modified titanium dioxide powder, where the mass fraction of ruthenium is 0.9%. The preparation method of the ruthenium-modified titanium dioxide powder is as follows: Immerse 10 g of nano-titanium dioxide powder in an aqueous ruthenium chloride solution containing 0.188 g of ruthenium chloride, then dry at 100 °C for 8 h, and then calcine at 500 °C for 8 h.

[0059] The heat exchanger is a shell-and-tube heat exchanger, and solenoid valves are installed on the first pipeline, the second pipeline, the third pipeline, the fourth pipeline, and the fifth pipeline.

[0060] The method for recycling low-carbon wind turbine blades using the low-carbon wind turbine blade recycling system of this embodiment is as follows:

[0061] A mixed gas composed of nitrogen and oxygen is used as the pyrolysis atmosphere, in which the volume content of oxygen is 5%. The pyrolysis atmosphere is preheated to 740 °C and introduced into the pyrolysis furnace from the pyrolysis atmosphere inlet at a gas flow rate of 15 L / min and allowed to continuously pass through the pyrolysis furnace. After removing the metal components from the waste wind turbine blade, it is cut into blocks (length × width = 10 cm × 10 cm), put into the pyrolysis furnace with the pyrolysis atmosphere from the waste wind turbine blade inlet, and pyrolyzed at 875 °C for 2.5 h to obtain relatively pure glass fibers. The pyrolysis tail gas enters the heat exchanger and exchanges heat with the pyrolysis atmosphere at room temperature. The cooled pyrolysis tail gas (160 °C) enters the reactor and is mixed with hydrogen at a molar ratio of 13:3, and reacts at 160 °C for 2 - 3 s under the action of a catalyst (the above-mentioned ruthenium-modified titanium dioxide powder filler) to convert carbon dioxide in the pyrolysis tail gas into methane, which is recycled as fuel. The pyrolysis atmosphere after heat exchange with the pyrolysis tail gas then enters the pyrolysis furnace.

[0062] Examples 2 - 5 are basically the same as Example 1, except that some process parameters are different.

[0063] The relevant process parameters of Examples 2 - 5 are shown in Table 1.

[0064] Table 1 Relevant process parameters of Examples 2 - 5

[0065]

[0066] II. Effect test

[0067] 1. Test method for glass fiber properties

[0068] (1) Fiber purity

[0069] A Mettler Toledo thermogravimetric analyzer is used to analyze the resin content in the glass fibers obtained after pyrolysis. The lower the content, the more complete the pyrolysis of the resin in the blade and the higher the fiber purity.

[0070] (2) Fiber strength retention rate

[0071] An LLY-06E tensile testing machine is used to measure the tensile strength of the glass fibers obtained after pyrolysis. The ratio of it to the strength of the original fibers represents the strength retention rate of the glass fibers obtained after pyrolysis. The larger the retention rate, the smaller the damage to the glass fibers during the pyrolysis process.

[0072] 2. Test method for carbon dioxide concentration in pyrolysis tail gas

[0073] A carbon dioxide gas sensor is used to detect the carbon dioxide content in the pyrolysis tail gas and the carbon dioxide content in the mixed gas obtained after the reaction of the pyrolysis tail gas with hydrogen.

[0074] 3. Test results

[0075] The fiber purity of the glass fibers obtained by the recovery methods of Examples 1-5, the fiber strength retention rate, the carbon dioxide concentration in the pyrolysis tail gas, and the carbon dioxide concentration in the mixed gas obtained after the reaction of the pyrolysis tail gas with hydrogen were detected, and the test results are shown in Table 2.

[0076] Table 2 Recovery effects of Examples 1-5

[0077] Item Fiber purity / % Fiber strength retention rate / % Carbon dioxide removal rate / % Example 1 98.1 88 94 Example 2 95 90 85 Example 3 97.5 84 99 Example 4 96 87 86 Example 5 97 86 96

[0078] As can be seen from Table 2, the catalyst of the present invention can improve the conversion rate of carbon dioxide and reduce the carbon dioxide emissions during the recovery process; at the same time, the present invention exchanges heat between the pyrolysis tail gas and the pyrolysis atmosphere to be fed into the pyrolysis furnace, greatly reducing the energy consumption, and the fiber quality obtained by pyrolysis is relatively high.

[0079] In the present invention, 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 the present invention. 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.

[0080] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A low-carbon method for recycling wind turbine blades, characterized in that, including Under a pyrolysis atmosphere, after removing the metal components from the waste wind turbine blade, pyrolysis is carried out to obtain glass fibers; the pyrolysis atmosphere is a mixed gas composed of nitrogen and oxygen, and the volume content of oxygen is between 4% and 6%; The pyrolysis tail gas is heat-exchanged with the pyrolysis atmosphere to obtain the heat-exchanged pyrolysis tail gas and the heat-exchanged pyrolysis atmosphere, and the heat-exchanged pyrolysis atmosphere is recycled for the pyrolysis; The heat-exchanged pyrolysis tail gas and hydrogen are reacted under the action of a catalyst, and carbon dioxide in the heat-exchanged pyrolysis tail gas is converted into methane; the catalyst is ruthenium-modified titanium dioxide powder, and the mass fraction of ruthenium is 0.8% - 1%; the reaction temperature of the heat-exchanged pyrolysis tail gas and hydrogen is 150 - 170 °C.

2. The low-carbon wind turbine blade recycling method according to claim 1, wherein The pyrolysis is carried out in a pyrolysis furnace; The pyrolysis atmosphere continuously passes through the pyrolysis furnace, and the flow rate is 10 - 20 L / min; The temperature of the pyrolysis atmosphere entering the pyrolysis furnace is 730 - 760 °C.

3. The low-carbon wind turbine blade recycling method according to claim 1, characterized in that, The temperature of the pyrolysis is 850 - 900 °C, and the pyrolysis time is 2 - 3 h.

4. The low-carbon wind turbine blade recycling method according to claim 1, wherein The temperature of the heat-exchanged pyrolysis tail gas is 150 - 170 °C.

5. The low-carbon wind turbine blade recycling method according to claim 1, wherein, The molar ratio of hydrogen to carbon dioxide in the heat-exchanged pyrolysis tail gas is between 4:1 and 9:

2.

6. The low-carbon wind turbine blade recycling method according to claim 1, wherein, The preparation method of the ruthenium-modified titanium dioxide powder is: impregnating nano-titanium dioxide powder in a soluble ruthenium salt solution, then drying at 80 - 120 °C for 6 - 10 h, and then calcining at 400 - 600 °C for 6 - 10 h.

7. A low-carbon wind turbine blade recycling system for the low-carbon wind turbine blade recycling method according to any one of claims 1 to 6, characterized in that, including A pyrolysis furnace, which has an inlet for waste wind turbine blades, an exhaust gas outlet, and an inlet for pyrolysis atmosphere; A heat exchanger, the hot side inlet of the heat exchanger is connected to the exhaust gas outlet, the cold side inlet of the heat exchanger is connected to the outlet of the pyrolysis atmosphere source, and the cold side outlet of the heat exchanger is connected to the pyrolysis atmosphere inlet; A reactor, which has a first inlet and a second inlet, the first inlet is connected to the hot side outlet of the heat exchanger, and the second inlet is connected to a hydrogen source.

8. The low-carbon wind turbine blade recycling system according to claim 7, characterized in that, The reactor is a packed tower; the heat exchanger is a tubular heat exchanger or a plate heat exchanger.

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