Decommissioned fan blade pyrolysis recovery method

Abstract

The invention provides a decommissioned fan blade pyrolysis recovery method, and belongs to the technical field of solid waste treatment. The method comprises the following steps: cutting the retired fan blade into a large material and a corner material; a swelling agent is applied to the bulk materials, the bulk materials are conveyed into a first transition isolation device and then adjusted to be in an anaerobic / anoxic atmosphere, then the first transition isolation device is communicated with a pyrolysis section, the bulk materials are conveyed into the pyrolysis section to be subjected to heating treatment, pyrolysis fibers are conveyed to a second transition isolation device and then adjusted to be in an oxidizing atmosphere, and pyrolysis is conducted; and then the second transition isolation device is communicated with the oxidation section, the pyrolyzed fibers are conveyed into the oxidation section to be heated, oxidized flue gas is generated, and the remaining fibers are recycled. According to the method provided by the invention, large materials are sequentially subjected to multiple steps of swelling, pyrolysis and low-temperature oxidation, and high-quality and long-size glass fibers are separated and recycled; and crushing and pyrolyzing the leftover materials to prepare pyrolytic carbon. And the transition isolation device prevents gas streaming, so that the whole recovery process can be continuously and efficiently carried out.

Description

Technical Field

[0001] This invention belongs to the field of solid waste treatment technology, specifically relating to a method for the pyrolysis recovery of decommissioned wind turbine blades. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Wind turbine blades are one of the most important components of wind power generation, and they are mainly composed of materials such as fiberglass, carbon fiber, balsa wood, and polyvinyl chloride (PVC). During their service life, wind turbine blades are subjected to multiple factors such as strong wind loads and ultraviolet radiation. When problems such as corrosion, bending deformation, and delamination cracking occur, they are gradually decommissioned.

[0004] Methods for recycling retired wind turbine blades include physical, chemical, and pyrolysis methods. In pyrolysis recycling schemes, installing equipment near the wind farm to pyrolyze the entire retired turbine blade presents challenges such as installation difficulties, difficulty in connecting with other exhaust gas treatment devices, and reduced energy utilization efficiency. While rotary walking beam or rotary kiln pyrolysis furnaces allow for continuous operation, they require the raw materials to be pulverized to a small size, and the resulting product is primarily low-value pyrolytic carbon.

[0005] In existing methods for pyrolysis recycling of decommissioned wind turbine blades, the blades need to be processed sequentially in different atmospheres and temperatures. Changes in atmosphere composition and temperature affect the quality of the recycled product. Continuous operation can effectively improve recycling efficiency. However, in the continuous recycling of decommissioned wind turbine blades, the different atmosphere requirements at each stage and the transport of materials between adjacent processing stages can cause gas crossflow and atmosphere fluctuations, affecting the quality of the recycled product. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for the pyrolysis recovery of decommissioned wind turbine blades. The decommissioned wind turbine blades are graded and cut into materials of various sizes for separate processing. This method can recover a variety of products, including large-sized fibers, pyrolytic carbon, and steam. Furthermore, before entering processing stages with different atmospheres and temperatures, a transition isolation device is used to adjust the atmospheric environment of the materials in advance, thereby improving the process stability of the entire continuous operation and enhancing the quality of the recovered products.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: A method for pyrolysis recovery of decommissioned wind turbine blades includes the following steps: S1. Cut the retired wind turbine blades into large pieces and scraps, and process them separately. S2. Large pieces of material are fed into the tunnel kiln. In the pretreatment section, a swelling agent is applied to the surface of the large pieces of material. After the large pieces of material are fed into the first transition isolation device, the channel between the two is closed, and the atmosphere of the first transition isolation device is adjusted to an oxygen-free / oxygen-deficient atmosphere. Then, the channel between the first transition isolation device and the pyrolysis section is opened, and the large pieces of material are fed into the pyrolysis section and heated to 500~650℃ in an oxygen-free / oxygen-deficient atmosphere for 30~50 minutes to generate the first pyrolysis gas and pyrolysis fibers. After the pyrolysis fibers are fed from the pyrolysis section to the second transition isolation device, the channel between the two is closed, and the atmosphere of the second transition isolation device is adjusted to an oxidizing atmosphere. Then, the channel between the second transition isolation device and the oxidation section is opened, and the pyrolysis fibers are fed into the oxidation section and heated to 400~500℃ in an oxidizing atmosphere for 40~60 minutes to generate oxidizing flue gas and recover the fibers. The size range of the large material is (1500~2000) × (1000~1500) × (100~150) mm. 3 .

[0008] The beneficial effects of this invention are as follows: 1. In the pyrolysis recovery method for decommissioned wind turbine blades provided by this invention, the decommissioned wind turbine blades are first segmented, retaining as many large fibers as possible to improve the utilization value of the recovered fibers. Then, the large pieces of material undergo multiple steps of swelling, pyrolysis, and low-temperature oxidation in different atmospheres to separate high-quality, long-sized glass fibers from the decommissioned wind turbine blades for recovery. The scrap materials are then crushed and pyrolyzed to prepare pyrolytic carbon. This yields both long-sized glass fibers and small-particle-size pyrolytic carbon, enriching the product variety. To ensure processing efficiency, a transition isolation device is used to separate the functional sections of the tunnel kiln, allowing only one upstream or downstream device to be connected. Before connecting the transition isolation device to an adjacent device, the atmosphere in the transition isolation device is adjusted to match the device to be connected, preventing gas cross-flow and ensuring stable atmosphere in each functional section. This improves the stability of the entire process, enabling continuous and efficient recovery.

[0009] 2. In the pyrolysis recovery method for decommissioned wind turbine blades provided by the present invention, both large pieces and scraps are treated at high temperatures, and the generated pyrolysis gas and oxidation flue gas can be mixed to achieve comprehensive utilization, reducing the difficulty of graded processing of materials. Attached Figure Description

[0010] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0011] Figure 1 This is a schematic diagram of the process for the pyrolysis recovery of decommissioned wind turbine blades in Example 1.

[0012] Figure 2 The diagram shows the structure of the first transition isolation device in Example 1. (a) is an isometric view, and (b) is a schematic diagram of the internal structure. Figure 1 (c) is a schematic diagram of the internal structure. Figure 2 .

[0013] Figure 3 This is a flowchart illustrating step S2 in Example 2.

[0014] Among them, 2. Cutting device; 3. Large material processing line; 32. Pretreatment section; 33. Pyrolysis section; 34. Oxidation section; 35. Second transition isolation device; 36. First cooling device; 37. Exhaust fan device; 38. First transition isolation device; 39. First incinerator; 310. Waste heat utilization device; 311. First flue gas purification device; 312. Third transition isolation device; 313. Fourth transition isolation device; 4. Edge material processing line; 42. Crushing device; 43. Feeding device; 44. Pyrolysis furnace; 45. Second cooling device; 46. Second incinerator; 47. Waste heat boiler; 48. Second flue gas purification device; 51. Shell; 513. Inlet; 514. Outlet; 52. Rotor; 521. Cavity; 522. Sealing ring; 54. Rotor motor; 55. Drive motor; 555. Conveyor roller; 56. Gas inlet and outlet. Detailed Implementation

[0015] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0016] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0017] One or more embodiments of the present invention provide a method for pyrolysis recovery of decommissioned wind turbine blades, comprising the following steps: S1. Cut the retired wind turbine blades into large pieces and scraps, and process them separately. S2. Large pieces of material are fed into the tunnel kiln. In the pretreatment section, a swelling agent is applied to the surface of the large pieces of material. After the large pieces of material are fed into the first transition isolation device, the atmosphere in the first transition isolation device is adjusted to an oxygen-free / oxygen-deficient atmosphere. Then, the first transition isolation device is connected to the pyrolysis section with the same oxygen-free / oxygen-deficient atmosphere. The large pieces of material are fed into the pyrolysis section and heated to 500~650℃ for 30~50 minutes to generate the first pyrolysis gas and pyrolysis fibers. After the pyrolysis fibers are fed into the second transition isolation device, the atmosphere in the second transition isolation device is adjusted to an oxidizing atmosphere. Then, the second transition isolation device is connected to the oxidation section with the same oxidizing atmosphere. The pyrolysis fibers are fed into the oxidation section and heated to 400~500℃ for 40~60 minutes to generate oxidizing flue gas. The remaining fibers are recovered. The size range of the large material is (1500~2000) × (1000~1500) × (100~150) mm. 3 .

[0018] The first transition isolation device and the second transition isolation device can only be connected to the upstream device or the downstream device in an airtight manner.

[0019] In the above process, after the decommissioned wind turbine blades are cut, the main processing involves large pieces of material. When the resin component in the large pieces of material comes into contact with the swelling agent, its dense structure expands and delaminates, and the surface exhibits a porous structure. This effectively improves heat and mass transfer during the depolymerization process, accelerates resin decomposition, inhibits the formation of pyrolytic carbon, and lowers the oxidation temperature, thus significantly improving the mechanical properties of the regenerated fibers. Pyrolysis is carried out in an oxygen-free / oxygen-deficient environment, generating pyrolysis gas and pyrolysis solids (glass fibers with residual pyrolytic carbon). In an oxygen-containing environment, the pyrolysis solids are heated and oxidized, and the pyrolytic carbon is transformed into pyrolysis flue gas, leaving large-sized recycled fibers. The size range of the large pieces of material matches the size range of the wind turbine blades and is retained as much as possible to preserve larger fibers. The crushed scraps are directly pyrolyzed in a rotary pyrolysis furnace, where resin, balsa wood fiber, and other components are transformed into pyrolytic carbon. At this point, the glass fibers mixed in are not separated, and the output is pyrolytic carbon containing glass fibers.

[0020] Optionally, in S1, the dimensions of the edge and corner materials are less than 500×400×100 mm. 3 The material distribution device collects large pieces of material and scrap material separately, and transports the large pieces of material into the tunnel kiln and the scrap material into the crushing device.

[0021] Optionally, in S2, after the large pieces of material are conveyed into the third transition isolation device of the tunnel kiln, the atmosphere in the third transition isolation device is adjusted to an oxygen-free / oxygen-deficient atmosphere. Then, the third transition isolation section is connected to the pretreatment section, which has the same oxygen-free / oxygen-deficient atmosphere, and the large pieces of material are then conveyed into the pretreatment section. The third transition isolation device can only be connected to either the upstream or downstream device in an airtight manner. In the pretreatment section, the atmosphere is adjusted to an oxygen-free / oxygen-deficient atmosphere, and the separation between the pyrolysis section and the outside world is increased through the third transition isolation device and the first transition isolation device, so as to maintain the oxygen-free / oxygen-deficient atmosphere and temperature stability of the pyrolysis section to the greatest extent.

[0022] Optionally, in S2, the method of applying the swelling agent includes: impregnating in the pretreatment section and spraying the swelling agent onto the surface of the bulk material using a swelling agent spraying device in the pretreatment section; the swelling agent can reduce the stability of the epoxy resin crosslinking structure, promote macromolecular decomposition, and cause the blade structure to expand and delaminate to form a porous surface.

[0023] Optionally, in S2, the heating method includes radiation / microwave heating; used to uniformly heat the surface and interior of large materials, suitable for large-scale continuous production.

[0024] Optionally, the oxygen content in the oxygen-free / oxygen-deficient environment is less than 100 ppm to prevent oxygen from reacting with epoxy resin or pyrolysis gas to generate heat and affect the temperature control effect.

[0025] Alternatively, the oxygen volume concentration in the oxygen-containing environment is 5-10%, which is used to slowly oxidize the carbon layer on the surface of the glass fiber to eliminate carbon residue on the surface.

[0026] Optionally, in S2, the fourth transition isolation device connects the oxidation section and the downstream section. After the fiber is transported to the fourth transition isolation device, the channel between the oxidation section and the fourth transition isolation device is sealed, and the fiber is transported to the first cooling device. The fourth transition isolation device can only be connected to either the upstream device or the downstream device in an airtight manner to increase the separation between the oxidation section and the outside world, and to maintain the stability of the atmosphere and temperature of the oxidation section to the greatest extent.

[0027] Optionally, in S2, the remaining fibers are recycled after being cooled by cold air purging in the first cooling device.

[0028] Optionally, step S3 involves crushing the scrap material and feeding it into a rotary pyrolysis furnace for pyrolysis at 450~500℃ to produce a second pyrolysis gas and pyrolysis char.

[0029] Optionally, in S3, the scrap material is fed into a crushing device for crushing, and then fed into a walking beam rotary pyrolysis furnace for pyrolysis in an oxygen-free / oxygen-deficient atmosphere.

[0030] Optionally, in S2 and S3, the first pyrolysis gas, the oxidation flue gas and / or the second pyrolysis gas are incinerated to generate incineration flue gas, the waste heat of the incineration flue gas is utilized, and the incineration flue gas is purified to meet the standards before being discharged; the incineration process is carried out in an incinerator to recover the chemical energy contained in the first / second pyrolysis gas and the oxidation flue gas, thereby reducing the energy consumption of the heating stage.

[0031] Optional waste heat utilization methods include: using waste heat boilers to recover waste heat from flue gas, which can output steam products, a common industrial product.

[0032] The present invention will be further described below with reference to the embodiments.

[0033] Example 1 Because the recycling process is a highly efficient continuous operation, materials need to be transported from the pyrolysis section, which requires an oxygen-free atmosphere, to the oxidation section, which requires an oxidizing atmosphere. In the pyrolysis section, a carbon layer remains on the surface of the glass fiber after resin pyrolysis. If oxidizing gases are mixed into the pyrolysis section, the oxidation of the residual carbon layer will cause exothermic reactions, resulting in unreasonable temperature rise of the glass fiber, which will greatly affect the mechanical properties of the glass fiber. Oxidizing gases will also react with the pyrolysis gas, not only reducing the calorific value of the pyrolysis gas, but also becoming an additional heat source inside the pyrolysis section, affecting the accuracy of temperature control. Similarly, the oxidation section also needs to control the atmosphere. If the content of oxidizing gases is too low, the residual carbon layer on the surface of the glass fiber will not be completely removed, resulting in substandard product purity. If the content of oxidizing gases is too high, the oxidation process will be too violent, which is not conducive to accurate temperature control. The atmosphere control and temperature control of adjacent pyrolysis and oxidation sections are different, and cross-contamination problems need to be avoided during continuous operation.

[0034] The recycling target in this embodiment is decommissioned wind turbine blades containing glass fibers with a modulus of 90-100 GPa. The recycling method is as follows: Figure 1 As shown, it includes: S1. Cutting device 2, based on the structural diagram or structural inspection results of the decommissioned wind turbine blades, preferentially cuts the decommissioned wind turbine blades into pieces with dimensions of 1500×1000×100mm. 3 Large pieces of material were removed, and the remaining material was cut into pieces smaller than 500×400×100mm. 3 The material distribution device sends large pieces of material to the large piece material processing line 3; the material distribution device sends the scrap material to the scrap material processing line 4.

[0035] S2, a tunnel kiln is set up on the large material processing line 3. Large materials are loaded onto material trays with screen holes at the bottom and conveyed in the tunnel kiln. An impregnation tank containing swelling agent is set up in the pretreatment section 32 of the tunnel kiln. The large materials on the material tray are impregnated in the impregnation tank and fully immersed in the swelling agent. After leaving the impregnation tank, the swelling agent is drained out from the screen holes of the material tray. The swelling agent is sprayed onto the surface of the large materials using the swelling agent spraying device in the pretreatment section 32. The impregnation and spraying swelling agent can reduce the stability of the epoxy resin cross-linking structure, promote the decomposition of macromolecules, and cause the blade structure to expand and delaminate to form a porous surface. The first transition isolation device 38 downstream of the pretreatment section 32 is then connected to the pretreatment section 32. After the bulk material is fed into the first transition isolation device 38, the channel between the first transition isolation device 38 and the pretreatment section 32 is closed. The first transition isolation device 38 introduces nitrogen through the gas inlet and outlet 56 and discharges the internal gas, gradually replacing the internal atmosphere of the first transition isolation device 38 with the same oxygen-free / oxygen-deficient atmosphere as the pyrolysis section 33, so that its oxygen content is below 100 ppm. Then, the channel between the first transition isolation device 38 and the downstream pyrolysis section 33 is opened, and the bulk material is conveyed to the pyrolysis section 33. The radiation / microwave heating device in the pyrolysis section 33 uniformly heats the interior and surface of the bulk material until the temperature reaches 600℃. After pyrolysis at this temperature for 30 minutes, it is sent to the downstream second transition isolation device 35. During pyrolysis, the nitrogen purging and replacement device continuously replenishes nitrogen to the pyrolysis section 33 to maintain the oxygen content below 100 ppm. In an oxygen-free / oxygen-deficient environment of ppm, the pyrolysis gas produced by pyrolysis is fed into the first incinerator 39 through the induced draft device 37, and the pyrolysis solids (glass fibers with residual pyrolysis carbon) produced by pyrolysis are sent into the second transition isolation device 35. After the material is completely fed into the second transition isolation device 35, the channel between the second transition isolation device 35 and the pyrolysis section 33 is closed. The second transition isolation device introduces hot air through the gas inlet and outlet 56 and discharges the internal gas, so that the internal atmosphere of the second transition isolation device 35 is adjusted to an oxidizing atmosphere with an oxygen volume concentration of 10%. The second transition isolation device 35 is then connected to the oxidation section 34 and the pyrolysis solid (glass fiber with residual pyrolysis carbon) is conveyed into the oxidation section 34. In the oxidation section 34, the nitrogen purging device and the hot air conveying device continue to provide the material with an oxygen-containing environment with an oxygen volume concentration of 10%. The heating device raises the temperature of the pyrolysis solid to 450°C and processes it in the oxidation section 34 for 40 minutes. During this process, the pyrolysis carbon reacts slowly in the oxidizing atmosphere and gradually transforms into pyrolysis flue gas, which is then conveyed into the first incinerator 39 through the induced draft device 37. After the pyrolysis solid is fed into the oxidation section 34, the channel between the second transition isolation device 35 and the oxidation section 34 is closed. Nitrogen is introduced through the gas inlet and outlet 56 and the internal gas is discharged, so that the internal atmosphere of the second transition isolation device 35 is adjusted to be consistent with the state of the upstream pyrolysis section 33. Then, when the second transition isolation device 35 and the pyrolysis section 33 are connected again, the internal atmosphere of the two is consistent, preventing the atmosphere of the pyrolysis section 33 from fluctuating. The remaining glass fibers, which do not contain pyrolytic carbon, are fed into the first cooling device 36. The cold air blowing device of the first cooling device 36 cools the glass fibers to below 50°C so that they can be output as a product.

[0036] The material handling processes in pyrolysis section 33 and oxidation section 34 are both carried out under normal pressure.

[0037] The high-temperature flue gas generated in the first incinerator 39 is divided into two paths. One path is sent to the outer wall interlayer of the pyrolysis section 33 and the oxidation section 34 to provide energy for the pyrolysis and oxidation reactions. The other path is sent to the waste heat recovery device 310 to recover waste heat. After the flue gas is treated and qualified by the first flue gas purification device 311, it is discharged into the atmosphere.

[0038] In the field of pyrolysis technology or industrial kiln equipment, the first transition isolation device 38 and the second transition isolation device 35 are usually referred to as "atmosphere isolation device" or "atmosphere lock", or "atmosphere isolation chamber" or "atmosphere transition zone"; they are used to prevent gas cross-flow between the two stages and to achieve the isolation between the oxygen-free / oxygen-deficient environment and the oxygen-containing environment required for pyrolysis.

[0039] S3. On the edge material processing line 4, edge materials enter the crushing device 42 and are crushed to a particle size ≤30mm. The crushed material is then fed into the rotary walking pyrolysis furnace 44 through the feeding device 43. The pyrolysis furnace 44 is filled with an oxidizing atmosphere formed by a hot air purging device. The flue gas generated during the pyrolysis process is fed into the second incinerator 46 for combustion. The flue gas generated during combustion is sent to the waste heat boiler 47 for waste heat recovery to obtain steam products. The flue gas after waste heat recovery is purified by the second flue gas purification device 48 and then discharged in compliance with standards. The pyrolysis solid output from the pyrolysis furnace 44 is pyrolysis char containing glass fiber. It is sent to the second cooling device 45 and cooled by the cold air purging device to become pyrolysis char products.

[0040] This pyrolytic carbon is a low-value pyrolytic carbon, mainly produced from resin, balsa wood, etc. in retired wind turbine blades. This pyrolytic carbon is mixed with glass fiber. Because of its low calorific value, it is no longer separated for economic and process considerations. The product obtained is pyrolytic carbon mixed with glass fiber.

[0041] In this embodiment, the first transition isolation device 38 and the second transition isolation device 35 have the same structure, such as... Figure 2 As shown in (a), it includes a cylindrical outer casing 51, the sidewall of which is provided with an inlet 513 communicating with an upstream device and an outlet 514 communicating with a downstream device; as Figure 2 As shown in (b), a rotor 52 is disposed inside the outer casing 51. The rotor 52 can rotate inside the outer casing 51 under the drive of the rotor motor 54, and the rotation axis of the rotor 52 coincides with the rotation center of the cylindrical outer casing 51. The rotor 52 includes a cavity 521 capable of accommodating large pieces of material. Figure 2 As shown in (b), the rotor 52 has a sealing ring 522 on its side wall, and the sealing ring 522 has only one opening with the same size as the inlet 513 / outlet 514: when the opening of the cavity 521 is connected to the inlet 513, the outlet 514 is closed by the sealing ring 522; when the opening of the cavity 521 is connected to the outlet 514, the inlet 513 is closed by the sealing ring 522, that is, it can only connect to the upstream device or the downstream device; the first transition isolation device 38 can only connect to the upstream pretreatment section 32 or the downstream pyrolysis section 33, or not connect to either; the second transition isolation device 35 can only connect to the upstream pyrolysis section 33 or the downstream oxidation section 34, or not connect to either.

[0042] The cavity 521 is equipped with a conveyor roller 555 driven by a drive motor 55 for conveying large pieces of material; the outer shell 51 is provided with multiple gas inlets and outlets 56, which can supply or extract gas into the cavity 521 to adjust the atmosphere in the first transition isolation device 38 and prevent gas cross-flow between upstream and downstream devices; during the time period when the first transition isolation device 38 or the second transition isolation device 35 is not connected to the upstream and downstream devices, the internal atmosphere is adjusted through the gas inlets and outlets 56 to be consistent with the internal atmosphere of the device that is about to be connected.

[0043] Example 2 The difference between the recycling method in this embodiment and that in Embodiment 1 is: like Figure 3 As shown, in S2, large pieces of material are first conveyed into the third transition isolation device 312 through the tunnel kiln inlet. After the atmosphere in the third transition isolation device 312 is adjusted to the same oxygen-free / oxygen-deficient atmosphere as the pretreatment section 32 by nitrogen purging, the third transition isolation device 312 is connected to the pretreatment section 32, and the large pieces of material are conveyed into the pretreatment section 32.

[0044] In S2, after the solid to be pyrolyzed is oxidized into glass fiber without pyrolytic carbon in the oxidation section 34, the glass fiber is transported into the fourth transition isolation device 313. After the channel between the fourth transition isolation device 313 and the oxidation section 34 is sealed, the fiber is transported to the first cooling device 36. The fourth transition isolation device 313 continuously inputs hot air to increase the separation between the oxidation section 34 and the outside world, so as to maintain the atmosphere and temperature stability of the oxidation section 34 to the greatest extent.

[0045] The structures of the third transition isolation device 312 and the fourth transition isolation device 313 are the same as those of the first transition isolation device 38. The third transition isolation device 312 can only be connected to either the upstream tunnel kiln inlet or the downstream pretreatment section 32, or it can not be connected to either of them. The fourth transition isolation device 313 can only be connected to either the upstream oxidation section 34 or the downstream first cooling device 36, or it can not be connected to either of them.

[0046] The temperature and time for the pyrolysis and oxidation processes were the same as in Example 1.

[0047] Comparative Example 1 The difference between this comparative example and Example 1 is that in S2, after the large material is pretreated in the pretreatment section 32, it enters the pyrolysis section 33 through the gate valve. After being processed in the pyrolysis section 33, it enters the oxidation section 34 through the gate valve. The atmosphere conditioning process is carried out in the pyrolysis section 33 and the oxidation section 34 respectively.

[0048] The gate valves between the pretreatment section 32, pyrolysis section 33, and oxidation section 34 are in a normally closed, airtight state. When material needs to pass through the gate valve to enter the next functional section, the gate valve opens to transport the material. After the material has completely entered the next functional section, the gate valve closes. The opening time of the gate valve is 15 seconds. During this time period, each functional section cannot maintain a stable internal atmosphere. After the gate valve closes, a set gas needs to be introduced into the internal space to restore the internal atmosphere to the set atmosphere. Similar to Example 1, the pyrolysis section 33 uses a nitrogen purging and replacement device to restore its atmosphere to an oxygen-free / oxygen-deficient state with an oxygen content of less than 100 ppm. The oxidation section 34 uses an internal nitrogen purging device and a hot air conveying device to restore its atmosphere to an oxygen-containing environment with an oxygen volume concentration of 10%.

[0049] However, in order to maintain continuous operation and process the material in the pyrolysis section at 600℃ for 30 minutes, followed by the oxidation section at 450℃ for 40 minutes, the process of inputting the set gas needs to be synchronized with the heating process. That is, in the initial stage of the heating process in the pyrolysis section 33, the material is not in the target oxygen-free / oxygen-deficient atmosphere, but in the process of recovering to the target oxygen-free / oxygen-deficient atmosphere. The glass fiber is prone to an unreasonable heating process. In the initial stage of the heating process in the oxidation section 34, the material is not in the target oxidation atmosphere, but in the process of recovering to the target oxygen-containing atmosphere, which affects the removal process of residual carbon attached to the glass fiber.

[0050] Comparative Example 2 The difference between this comparative example and comparative example 1 is that in S2, after the large material is pretreated in the pretreatment section 32, it enters the pyrolysis section 33 through the same first transition isolation device 38 as in example 1. After being processed in the pyrolysis section 33, the material enters the oxidation section 34 through the same gate valve as in comparative example 1. In order to prevent the gas in the oxidation section 34 from entering the pyrolysis section 33, the gas pressure in the pyrolysis section 33 is controlled to be 100 Pa higher than the gas pressure in the oxidation section.

[0051] There will be virtually no atmosphere fluctuations at the inlet and outlet of the pyrolysis section 33, but atmosphere fluctuations will occur at the inlet and outlet of the oxidation section 34; after the material undergoes a pyrolysis process that is basically the same as in Example 1, it will then undergo an oxidation process that is the same as in Comparative Example 1.

[0052] Comparative Example 3 The difference between this comparative example and comparative example 1 is that in S2, after the large material is pretreated in the pretreatment section 32, it enters the pyrolysis section through the same gate valve as comparative example 1. After being processed in the pyrolysis section 33, the material enters the oxidation section 34 through the same second transition isolation device 35 as in example 1.

[0053] No atmosphere fluctuations will occur at the inlet of oxidation section 34, but atmosphere fluctuations will occur at the inlet of pyrolysis section 33, the outlet of pyrolysis section 33 and the outlet of oxidation section 34, so that the material undergoes the same pyrolysis process as Comparative Example 1, and then undergoes the same oxidation process as Example 1.

[0054] The residual carbon content and tensile strength retention rate of the glass fibers recovered after processing the bulk materials in Examples 1, 2 and 1 were tested respectively, and the results are shown in Table 1.

[0055] Table 1. Statistical Table of Residual Carbon Content and Tensile Strength Retention Rate

[0056] The above demonstrates that the technical solutions of Examples 1 and 2 can be used for continuous operation of pyrolysis recycling of decommissioned wind turbine blades. The glass fibers recovered from bulk materials have good mechanical properties and low impurity content. However, the anaerobic / anoxic environment during the pyrolysis process of Comparative Examples 1 and 3 is unstable, resulting in lower mechanical properties. Furthermore, the oxidizing atmosphere during the oxidation process of Comparative Examples 1 and 2 is difficult to maintain, resulting in higher impurity content.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for pyrolysis recovery of decommissioned wind turbine blades, characterized in that, Including the following steps: S1. Cut the retired wind turbine blades into large pieces and scraps, and process them separately. S2. Large pieces of material are fed into the tunnel kiln. In the pretreatment section, a swelling agent is applied to the surface of the large pieces of material. After the large pieces of material are fed into the first transition isolation device, the channel between the two is closed, and the atmosphere of the first transition isolation device is adjusted to an oxygen-free / oxygen-deficient atmosphere. Then, the channel between the first transition isolation device and the pyrolysis section is opened, and the large pieces of material are fed into the pyrolysis section and heated to 500~650℃ in an oxygen-free / oxygen-deficient atmosphere for 30~50 minutes to generate the first pyrolysis gas and pyrolysis fibers. After the pyrolysis fibers are fed into the second transition isolation device, the atmosphere of the second transition isolation device is adjusted to an oxidizing atmosphere. Then, the channel between the second transition isolation device and the oxidation section is opened, and the pyrolysis fibers are fed into the oxidation section and heated to 400~500℃ in an oxidizing atmosphere for 40~60 minutes to generate oxidizing flue gas and recover the fibers. The size range of the large material is (1500~2000) × (1000~1500) × (100~150) mm. 3 .

2. The method for pyrolysis recovery of decommissioned wind turbine blades as described in claim 1, characterized in that, In S1, the dimensions of the corner material are less than 500×400×100 mm. 3 The material distribution device collects large pieces of material and scrap material separately, and transports the large pieces of material into the tunnel kiln and the scrap material into the crushing device.

3. The method for pyrolysis recovery of decommissioned wind turbine blades as described in claim 1, characterized in that, After the large pieces of material are conveyed into the third transition isolation device of the tunnel kiln, the atmosphere in the third transition isolation device is adjusted to an oxygen-free / oxygen-deficient atmosphere. Then, the third transition isolation section is connected to the pretreatment section with the same oxygen-free / oxygen-deficient atmosphere. After that, the large pieces of material are conveyed into the pretreatment section. The third transition isolation device can only be connected to either the tunnel kiln inlet or the downstream pretreatment section in an airtight manner.

4. The method for pyrolysis recovery of decommissioned wind turbine blades as described in claim 1, characterized in that, In S2, the method of applying the swelling agent includes: impregnating in the pretreatment section and spraying the swelling agent onto the surface of the bulk material using the swelling agent spraying device in the pretreatment section.

5. The method for pyrolysis recovery of decommissioned wind turbine blades as described in claim 1, characterized in that, In S2, the heating methods include radiation / microwave heating; The oxygen content in the anoxic / hypoxic environment is less than 100 ppm; The oxygen volume concentration in the oxygen-containing environment is 5-10%.

6. The method for pyrolysis recovery of decommissioned wind turbine blades as described in claim 1, characterized in that, In S2, the oxidation section is connected to the downstream fourth transition isolation device. After the fiber is transported to the fourth transition isolation device, the channel between the oxidation section and the fourth transition isolation device is sealed, and the fiber is transported to the first cooling device. The fourth transition isolation device can only connect to either the oxidation section or the first cooling device in an airtight manner.

7. The method for pyrolysis recovery of decommissioned wind turbine blades as described in claim 1, characterized in that, In S2, the remaining fibers are recycled after being cooled by cold air in the first cooling device.

8. The method for pyrolysis recovery of decommissioned wind turbine blades as described in claim 1, characterized in that, Including step S3, crushing the scrap material and feeding it into a rotary pyrolysis furnace for pyrolysis at 450~500℃ to produce second pyrolysis gas and pyrolysis char; After being crushed by the crushing device, the scrap material is fed into the walking beam rotary pyrolysis furnace for pyrolysis in an oxygen-free / oxygen-deficient atmosphere.

9. The method for pyrolysis recovery of decommissioned wind turbine blades as described in any one of claims 1-8, characterized in that, In S2 and S3, the first pyrolysis gas, the oxidation flue gas and / or the second pyrolysis gas are incinerated to generate incineration flue gas. The waste heat of the incineration flue gas is utilized, and the incineration flue gas is purified to meet the standards before being discharged.

10. The method for pyrolysis recovery of decommissioned wind turbine blades as described in claim 9, characterized in that, Waste heat utilization methods include: using waste heat from flue gas to heat the pyrolysis section, oxidation section, and / or rotary pyrolysis furnace.

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