Method for recycling regenerated fibers from retired fan blades

Abstract

The invention provides a method for recycling regenerated fibers from retired fan blades, and belongs to the technical field of resource recycling. The method for recycling the regenerated fibers from the retired fan blade comprises the following steps: cutting the retired fan blade to obtain a blade block; the blade block is subjected to a pyrolytic reaction in the air atmosphere, and regenerated fibers are obtained; the temperature of the pyrolytic reaction ranges from 500 DEG C to 700 DEG C, and the time of the pyrolytic reaction ranges from 120 min to 240 min; and the flow velocity of the air is 0.2-0.5 m / s. According to the invention, the retired fan blade is cut, so that the problem of local overheating or non-uniform heating caused by pyrolysis of bulk materials can be avoided, and uniform pyrolysis of the blade bulk materials can be ensured, so that epoxy resin can be completely decomposed; by limiting the flow velocity of air and the temperature and time of the pyrolytic reaction, the damage to the performance of the regenerated fiber can be reduced on the basis of decomposing the epoxy resin, so that the mechanical property of the regenerated fiber is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of resource recovery, and in particular relates to a method for recovering regenerated fibers from retired wind turbine blades. Background Art

[0002] Wind turbine blades are one of the core components of wind turbines. They have excellent properties such as low weight, high strength, corrosion resistance and fatigue resistance. Their mass can account for up to 90% of the entire wind turbine blade. At present, wind turbine blades are mainly made of thermosetting resin-based composite materials reinforced with glass fiber, carbon fiber or a mixture. Retired wind turbine blades mainly use fluidized bed technology. Based on the principle of gas-solid fluidization, the resin matrix of retired wind turbine blades is pyrolyzed by high-temperature hot air on the fluidized bed, while retaining the fiber material. In this process, the resin matrix is ​​decomposed into small molecular gases (such as hydrogen, carbon monoxide and carbon dioxide, etc.) and liquids (such as tar), while the fiber material remains relatively intact, thereby achieving effective separation of fiber and resin.

[0003] Although fluidized bed technology has certain feasibility in recycling waste fan blades, the performance of the recycled fibers recovered by fluidized bed technology is somewhat different from that of the original materials, which affects the effect of subsequent reuse. Therefore, how to improve the mechanical properties of recycled fibers has become a technical problem that technicians in this field need to solve urgently. Summary of the invention

[0004] The object of the present invention is to provide a method for recovering regenerated fibers from retired wind turbine blades. The regenerated fibers recovered by the method provided by the present invention have excellent mechanical properties.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for recovering regenerated fibers from retired wind turbine blades, comprising the following steps:

[0007] (1) Cutting retired wind turbine blades to obtain blade blocks;

[0008] (2) subjecting the blade block obtained in step (1) to a pyrolysis reaction in an air atmosphere to obtain regenerated fiber; the pyrolysis reaction temperature is 500 to 700° C., the pyrolysis reaction time is 120 to 240 min; and the air flow rate is 0.2 to 0.5 m / s.

[0009] Preferably, the step (1) further includes removing metal components before cutting the retired wind turbine blades.

[0010] Preferably, the size of the blade block in step (1) is (20-30)×(20-30) mm.

[0011] Preferably, the pyrolysis reaction in step (2) is carried out in a circulating fluidized bed.

[0012] Preferably, the circulating fluidized bed is a silica sand bed, and the particle size of the silica sand in the silica sand bed is 0.1-0.4 mm.

[0013] Preferably, the thickness of the silica sand bed is 100-120 mm.

[0014] Preferably, the temperature of the pyrolysis reaction in step (2) is 520-680°C.

[0015] Preferably, the temperature of the pyrolysis reaction in step (2) is 560-640°C.

[0016] Preferably, the pyrolysis reaction time in step (2) is 150 to 210 minutes.

[0017] Preferably, the flow rate of the air in step (2) is 0.3-0.4 m / s.

[0018] The present invention provides a method for recovering regenerated fibers from retired fan blades, comprising the following steps: cutting retired fan blades to obtain blade blocks; subjecting the blade blocks to pyrolysis reaction in an air atmosphere to obtain regenerated fibers; the temperature of the pyrolysis reaction is 500-700°C, the time of the pyrolysis reaction is 120-240 minutes; the flow rate of the air is 0.2-0.5 m / s. The present invention cuts retired fan blades to avoid the problem of local overheating or uneven heating caused by pyrolysis of large blocks of materials, ensures that the blade blocks can be pyrolyzed evenly, so that the epoxy resin can be completely decomposed. Afterwards, during the pyrolysis reaction, by limiting the flow rate of air, the temperature and time of the pyrolysis reaction, the damage to the performance of the regenerated fiber can be reduced on the basis of decomposing the epoxy resin, thereby improving the mechanical properties of the regenerated fiber. Experimental results show that the tensile strength retention rate of the regenerated fiber prepared by the method provided by the present invention reaches more than 70%. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The schematic diagram of the circulating fluidized bed structure is shown in Figure 2.

[0020] In the figure, 1 is an air compressor, 2 is a mass flow meter, 3 is a screw feeder, 4 is a lower flue gas measuring point, 5 is an upper flue gas measuring point, 6 is a gas analyzer, and 7 is a cyclone separator;

[0021] Figure 2 This is the SEM image of the regenerated fiber prepared in Example 1. DETAILED DESCRIPTION

[0022] The present invention provides a method for recovering regenerated fibers from retired wind turbine blades, comprising the following steps:

[0023] (1) Cutting retired wind turbine blades to obtain blade blocks;

[0024] (2) subjecting the blade block obtained in step (1) to a pyrolysis reaction in an air atmosphere to obtain regenerated fiber; the pyrolysis reaction temperature is 500 to 700° C., the pyrolysis reaction time is 120 to 240 min; and the air flow rate is 0.2 to 0.5 m / s.

[0025] The method provided by the present invention is applicable to retired wind turbine blades made of any material.

[0026] The present invention has no particular limitation on the source of the retired wind turbine blades, and commercially available products known to those skilled in the art may be used.

[0027] The present invention cuts the retired fan blades to obtain blade blocks. The present invention cuts the retired fan blades to avoid the problem of local overheating or uneven heating caused by pyrolysis of large blocks of materials, ensuring that the blade blocks can be evenly pyrolyzed, thereby completely decomposing the epoxy resin.

[0028] In the present invention, the decommissioned wind turbine blades preferably include removing metal components before cutting. The present invention has no special limitation on the operation of removing the metal components, and operations well known to those skilled in the art can be used.

[0029] The present invention has no special limitation on the cutting operation, as long as the blade blocks of the required size are obtained.

[0030] In the present invention, the size of the blade block is preferably (20-30)×(20-30) mm, more preferably 25×25 mm. The present invention limits the size of the blade block to the above range to avoid the problem of local overheating or uneven heating caused by the pyrolysis of large blocks of material; ensure that each small block of material can be evenly contacted with the high-temperature medium to improve the efficiency of material decomposition; at the same time, heat can penetrate faster and decompose the epoxy resin, thereby shortening the pyrolysis time and improving the overall processing efficiency.

[0031] After obtaining the blade block, the present invention performs a pyrolysis reaction on the blade block in an air atmosphere to obtain regenerated fibers.

[0032] In the present invention, the temperature of the pyrolysis reaction is 500-700°C; the time of the pyrolysis reaction is 120-240 minutes; the flow rate of the air is 0.2-0.5 m / s. The present invention can reduce the damage to the performance of the regenerated fiber on the basis of decomposing the epoxy resin by limiting the flow rate of the air, the temperature and time of the pyrolysis reaction, thereby improving the mechanical properties of the regenerated fiber.

[0033] As an embodiment, the temperature of the pyrolysis reaction may be 520-680°C, or may be 560°C, 580°C, 600°C or 640°C.

[0034] As an embodiment, the pyrolysis reaction time may be 150 to 210 minutes, or may be 180 minutes.

[0035] As an implementation manner, the flow rate of the air may be 0.3-0.4 m / s.

[0036] In the present invention, the pyrolysis reaction is preferably carried out in a circulating fluidized bed; the circulating fluidized bed is preferably a silica sand bed; the particle size of the silica sand in the silica sand bed is preferably 0.1-0.4 mm; the thickness of the silica sand bed is preferably 100-120 mm, more preferably 110 mm. The present invention limits the particle size of the silica sand to the above range, so that the silica sand has a larger specific surface area, which is conducive to heat and mass transfer, can improve the rate and uniformity of the pyrolysis reaction, and make the decomposition of organic matter more thorough.

[0037] The present invention has no special limitation on the total mass of silica sand in the circulating fluidized bed, and it can be adjusted according to actual needs.

[0038] As an embodiment, the total mass of silica sand in the circulating fluidized bed may be 3 kg.

[0039] As an embodiment, the circulating fluidized bed may be a circulating fluidized bed with a power of 15 kW.

[0040] After the pyrolysis reaction is completed, the present invention preferably cools the product obtained by the pyrolysis reaction and takes it out to obtain regenerated fiber.

[0041] The present invention has no particular limitation on the cooling and taking-out operations, and operations well known to those skilled in the art may be adopted.

[0042] The present invention processes retired fan blades through circulating fluidized bed pyrolysis technology, optimizes the operating parameters of the circulating fluidized bed (air flow rate, temperature and time of pyrolysis reaction), obtains the best recovery effect, and improves recovery efficiency and fiber quality; at the same time, it avoids the waste of resources caused by landfill treatment and the toxic and harmful gases generated by direct incineration, successfully recovers fibers with clean surfaces and good performance, and avoids the damage to fiber performance and increase in system energy consumption caused by other processes such as combustion or mechanical separation and other post-treatment processes; the method can directly obtain fibers with clean surfaces and good mechanical properties; the tensile strength retention rate of the regenerated fibers reaches more than 70%.

[0043] The method proposed in the present invention can effectively achieve the reduction, harmlessness and resource processing of retired wind turbine blades, can reduce environmental pollution and achieve sustainable development; through recycling and reuse, a large amount of raw materials and energy consumption can be saved, which helps to reduce production costs and also helps to alleviate the problem of resource shortages.

[0044] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] The materials in the examples were prepared according to existing methods or directly purchased from the market;

[0046] In the embodiment, the tensile strength retention rate of the regenerated fiber is used as the evaluation index of the recycling effect, and the calculation formula is shown in Formula I:

[0047]

[0048] In formula I, X is the tensile strength retention rate of the regenerated fiber, in %, σ is the tensile strength of the regenerated fiber, in MPa; σ0 is the tensile strength of the original fiber, in MPa.

[0049] The pyrolysis reactions in the embodiments are all carried out in a circulating fluidized bed with a power of 15 kW. The structural schematic diagram of the circulating fluidized bed is shown in FIG. Figure 1 As shown, Figure 1 In the figure, 1 is an air compressor, 2 is a mass flow meter, 3 is a screw feeder, 4 is a lower flue gas measuring point, 5 is an upper flue gas measuring point, 6 is a gas analyzer, and 7 is a cyclone separator.

[0050] Calculated by mass percentage, the retired wind turbine blades used in the embodiment are composed of: 30% epoxy resin, 60% glass fiber, and 10% sandwich material, adhesive and auxiliary materials.

[0051] Example 1

[0052] The method for recovering recycled fiber from retired wind turbine blades is as follows:

[0053] (1) Remove the metal components on the retired wind turbine blades and then cut them mechanically to obtain blade blocks with a size of 25×25 mm;

[0054] (2) 3 kg of silica sand with a particle size of 0.1 to 0.4 mm is added to the circulating fluidized bed through a screw feeder to form a silica sand bed with a thickness of 110 mm, and then the blade block obtained in step (1) is subjected to a pyrolysis reaction for 180 min at an air flow rate of 0.3 m / s and a temperature of 520° C., and then the circulating fluidized bed is cooled down as a whole and then taken out to obtain regenerated fiber.

[0055] Figure 2 This is the SEM image of the regenerated fiber prepared in Example 1.

[0056] from Figure 2 It can be seen that the regenerated fiber (glass fiber) exhibits a rough surface at this temperature, which indicates the presence of residual organic matter. This organic matter is likely to come from the silane coating applied during fiber processing or from the glass fiber surface.

[0057] Example 2

[0058] The method for recovering recycled fiber from retired wind turbine blades is as follows:

[0059] (1) Remove the metal components on the retired wind turbine blades and then cut them mechanically to obtain blade blocks with a size of 25×25 mm;

[0060] (2) 3 kg of silica sand with a particle size of 0.1 to 0.4 mm is added to the circulating fluidized bed through a screw feeder to form a silica sand bed with a thickness of 110 mm, and then the blade block obtained in the step (1) is subjected to a pyrolysis reaction for 180 min at an air flow rate of 0.3 m / s and a temperature of 560° C., and then the circulating fluidized bed is cooled down as a whole and then taken out to obtain regenerated fiber.

[0061] Example 3

[0062] The method for recovering recycled fiber from retired wind turbine blades is as follows:

[0063] (1) Remove the metal components on the retired wind turbine blades and then cut them mechanically to obtain blade blocks with a size of 25×25 mm;

[0064] (2) 3 kg of silica sand with a particle size of 0.1 to 0.4 mm is added to the circulating fluidized bed through a screw feeder to form a silica sand bed with a thickness of 110 mm, and then the blade block obtained in step (1) is subjected to a pyrolysis reaction for 180 min at an air flow rate of 0.3 m / s and a temperature of 600° C., and then the circulating fluidized bed is cooled down as a whole and then taken out to obtain regenerated fiber.

[0065] Example 4

[0066] The method for recovering recycled fiber from retired wind turbine blades is as follows:

[0067] (1) Remove the metal components on the retired wind turbine blades and then cut them mechanically to obtain blade blocks with a size of 25×25 mm;

[0068] (2) 3 kg of silica sand with a particle size of 0.1 to 0.4 mm is added to the circulating fluidized bed through a screw feeder to form a silica sand bed with a thickness of 110 mm, and then the blade block obtained in the step (1) is subjected to a pyrolysis reaction for 180 min at an air flow rate of 0.3 m / s and a temperature of 640° C., and then the circulating fluidized bed is cooled down as a whole and then taken out to obtain regenerated fiber.

[0069] Example 5

[0070] The method for recovering recycled fiber from retired wind turbine blades is as follows:

[0071] (1) Remove the metal components on the retired wind turbine blades and then cut them mechanically to obtain blade blocks with a size of 25×25 mm;

[0072] (2) 3 kg of silica sand with a particle size of 0.1 to 0.4 mm is added to the circulating fluidized bed through a screw feeder to form a silica sand bed with a thickness of 110 mm, and then the blade block obtained in the step (1) is subjected to a pyrolysis reaction for 180 min at an air flow rate of 0.3 m / s and a temperature of 680° C., and then the circulating fluidized bed is cooled down as a whole and then taken out to obtain regenerated fiber.

[0073] Example 6

[0074] The method for recovering recycled fiber from retired wind turbine blades is as follows:

[0075] (1) Remove the metal components on the retired wind turbine blades and then cut them mechanically to obtain blade blocks with a size of 25×25 mm;

[0076] (2) 3 kg of silica sand with a particle size of 0.1 to 0.4 mm is added to the circulating fluidized bed through a screw feeder to form a silica sand bed with a thickness of 110 mm, and then the blade block obtained in step (1) is subjected to a pyrolysis reaction for 180 min at an air flow rate of 0.4 m / s and a temperature of 560° C., and then the circulating fluidized bed is cooled down as a whole and then taken out to obtain regenerated fiber.

[0077] Example 7

[0078] The method for recovering recycled fiber from retired wind turbine blades is as follows:

[0079] (1) Remove the metal components on the retired wind turbine blades and then cut them mechanically to obtain blade blocks with a size of 25×25 mm;

[0080] (2) 3 kg of silica sand with a particle size of 0.1 to 0.4 mm is added to the circulating fluidized bed through a screw feeder to form a silica sand bed with a thickness of 110 mm, and then the blade block obtained in the step (1) is subjected to a pyrolysis reaction at an air flow rate of 0.5 m / s and a temperature of 560° C. for 180 min, and then the circulating fluidized bed is cooled down as a whole and then taken out to obtain regenerated fiber.

[0081] Example 8

[0082] The method for recovering recycled fiber from retired wind turbine blades is as follows:

[0083] (1) Remove the metal components on the retired wind turbine blades and then cut them mechanically to obtain blade blocks with a size of 25×25 mm;

[0084] (2) 3 kg of silica sand with a particle size of 0.1 to 0.4 mm is added to the circulating fluidized bed through a screw feeder to form a silica sand bed with a thickness of 110 mm, and then the blade block obtained in the step (1) is subjected to a pyrolysis reaction at an air flow rate of 0.4 m / s and a temperature of 560° C. for 210 min. After the circulating fluidized bed is cooled down as a whole, it is taken out to obtain regenerated fiber.

[0085] Example 9

[0086] The method for recovering recycled fiber from retired wind turbine blades is as follows:

[0087] (1) Remove the metal components on the retired wind turbine blades and then cut them mechanically to obtain blade blocks with a size of 25×25 mm;

[0088] (2) 3 kg of silica sand with a particle size of 0.1 to 0.4 mm is added to the circulating fluidized bed through a screw feeder to form a silica sand bed with a thickness of 110 mm, and then the blade block obtained in the step (1) is subjected to a pyrolysis reaction at an air flow rate of 0.4 m / s and a temperature of 560° C. for 240 min. After the circulating fluidized bed is cooled down as a whole, it is taken out to obtain regenerated fiber.

[0089] Example 10

[0090] The method for recovering recycled fiber from retired wind turbine blades is as follows:

[0091] (1) Remove the metal components on the retired wind turbine blades and then cut them mechanically to obtain blade blocks with a size of 25×25 mm;

[0092] (2) 3 kg of silica sand with a particle size of 0.1 to 0.4 mm is added to the circulating fluidized bed through a screw feeder to form a silica sand bed with a thickness of 110 mm, and then the blade block obtained in step (1) is subjected to a pyrolysis reaction for 150 min at an air flow rate of 0.4 m / s and a temperature of 560° C., and then the circulating fluidized bed is cooled down as a whole and then taken out to obtain regenerated fiber.

[0093] Embodiment 11

[0094] The method for recovering recycled fiber from retired wind turbine blades is as follows:

[0095] (1) Remove the metal components on the retired wind turbine blades and then cut them mechanically to obtain blade blocks with a size of 25×25 mm;

[0096] (2) 3 kg of silica sand with a particle size of 0.1 to 0.4 mm is added to the circulating fluidized bed through a screw feeder to form a silica sand bed with a thickness of 110 mm, and then the blade block obtained in the step (1) is subjected to a pyrolysis reaction for 120 min at an air flow rate of 0.4 m / s and a temperature of 560° C., and then the circulating fluidized bed is cooled down as a whole and then taken out to obtain regenerated fiber.

[0097] The regenerated (glass) fibers prepared in Examples 1 to 11 were subjected to a tensile test according to ASTM C1557-0. The results are shown in Table 1. The tensile strength of the original fibers was 1000 MPa.

[0098] Table 1 Process parameters of the embodiment and performance data of the regenerated (glass) fiber

[0099]

[0100] It can be seen from Table 1 that the tensile strength of the regenerated (glass) fibers prepared by the method provided by the present invention has a good retention rate, which proves that the method proposed by the present invention has an excellent recycling effect.

[0101] It can be seen from the above examples that the regenerated fiber recovered by the method provided by the present invention has excellent mechanical properties.

[0102] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for recovering regenerated fibers from retired wind turbine blades, characterized in that: The following steps are involved: (1) Cutting retired wind turbine blades to obtain blade blocks; (2) subjecting the blade block obtained in step (1) to a pyrolysis reaction in an air atmosphere to obtain regenerated fiber; the pyrolysis reaction temperature is 500 to 700° C., the pyrolysis reaction time is 120 to 240 min; and the air flow rate is 0.2 to 0.5 m / s.

2. The method according to claim 1, characterized in that The step (1) also includes removing metal components before cutting the retired wind turbine blades.

3. The method according to claim 1, characterized in that The size of the blade block in step (1) is (20-30)×(20-30) mm.

4. The method according to claim 1, characterized in that The pyrolysis reaction in step (2) is carried out in a circulating fluidized bed.

5. The method according to claim 4, characterized in that The circulating fluidized bed is a silica sand bed, and the particle size of the silica sand in the silica sand bed is 0.1-0.4 mm.

6. The method according to claim 5, characterized in that The thickness of the silica sand bed is 100-120 mm.

7. The method according to claim 1, characterized in that The temperature of the pyrolysis reaction in step (2) is 520-680°C.

8. The method according to claim 1 or 7, characterized in that: The temperature of the pyrolysis reaction in step (2) is 560-640°C.

9. The method according to claim 1, characterized in that: The time of the pyrolysis reaction in step (2) is 150 to 210 minutes.

10. The method according to claim 1, characterized in that The flow rate of the air in step (2) is 0.3-0.4 m / s.

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