A wind power blade on-site interval type laser pyrolysis recycling method and device

Abstract

The present application relates to the field of wind turbine blade composite material recycling, and discloses a wind turbine blade on-site interval type laser pyrolysis recycling method and device, which comprises intermittent laser heating along the surface of the blade to form alternating pyrolysis sections and non-pyrolysis sections, and the non-pyrolysis sections retain the resin as flexible connection sections; during the heating process, independent control is performed on the blade in the circumferential direction to form multiple independent heating tracks, and the annular cross section of the blade is divided into multiple independent fiber bundle strips; after the pyrolysis is completed, the blade is bent along the non-pyrolysis sections, the fiber bundle strips are independently folded and stacked, and a laminated structure conforming to the loading size of a conventional truck is formed. The device comprises an annular shell, a moving driving mechanism and a partition-controlled laser array, and can realize on-site operation. The present application eliminates the traditional mechanical cutting process, directly solves the problem of over-limit transportation faced by large retired blades, significantly reduces the logistics cost and maintains the length and strength of the recycled fibers.

Description

Technical Field

[0001] This invention relates to the field of wind turbine blade composite material recycling technology, specifically to a method and apparatus for on-site intermittent laser pyrolysis recycling of wind turbine blades. Background Technology

[0002] Wind turbine blades are primarily composed of glass fiber or carbon fiber reinforced resin composite materials, characterized by their large length, wide width, hollow structure, and gradually varying cross-sectional thickness. As early wind turbine units reach the end of their design life, a large number of decommissioned blades require proper disposal. Conventional landfill or incineration wastes resources and causes environmental pollution, and is subject to strict restrictions from local policies. Direct mechanical crushing severely damages the original fiber length in the composite material, leading to a decline in the mechanical properties of the recycled products, rendering them only suitable for use as low-value fillers.

[0003] To achieve high-value recycling, pyrolysis technology has gradually become a focus of the industry. Conventional thermochemical recycling mainly relies on stationary pyrolysis furnaces, which must be built in fixed plant areas. Due to the large size of retired blades, they need to be cut into smaller pieces on-site at the wind farm before long-distance transportation. The cutting operation itself incurs high costs, and the road transportation of large components is heavily reliant on specialized vehicles, with logistics costs accounting for a large proportion of the total recycling cost. In addition, the traditional pyrolysis furnace's overall heating method has high energy consumption, and the total amount of waste gas generated by the thermal decomposition of resin is large, with a high tar content, resulting in high investment and operating costs for subsequent environmental treatment systems.

[0004] To address the aforementioned cutting and transportation issues, some studies have attempted continuous pyrolysis of the entire blade without physical cutting. However, after resin removal, this method leaves continuous fibers that remain tens of meters long and exhibit rigidity that makes them difficult to bend, failing to solve the fundamental problem of transporting bulky materials. Furthermore, wind turbine blades exhibit significant thickness and cross-sectional variations from the blade root to the tip, and existing continuous heating methods are ill-suited to this variable cross-section, easily leading to resin residue in thick-walled areas or fiber burnout in thin-walled areas. Simultaneously, existing heating processes often struggle to effectively seal and collect pyrolysis exhaust gases on long structural surfaces. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method and apparatus for on-site intermittent laser pyrolysis recycling of wind turbine blades, which solves the problems of high logistics costs for oversized transportation of large decommissioned wind turbine blades due to their large size, difficulties in on-site in-situ processing, and the damage to the physical continuity of fibers caused by traditional mechanical cutting.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The first aspect of this invention provides a method for on-site intermittent laser pyrolysis recovery of wind turbine blades, comprising: Intermittent laser heating is performed along the blade surface in the blade length direction to form alternating pyrolysis and non-pyrolysis sections. In the pyrolysis section, the resin is pyrolyzed and vaporized and the fibers are exposed, while in the non-pyrolysis section, the resin is not heated and is retained as a flexible connection section. During the intermittent laser heating process, independent heating control is performed in the circumferential direction of the blade, forming multiple independent heating tracks extending along the length direction on the blade surface, dividing the annular cross section of the blade into multiple independent fiber bundles. After pyrolysis, the blade is bent along the unpyrolyzed section, causing the multiple independent fiber bundles to separate and fold independently, forming a layered structure.

[0008] The above technical solution utilizes laser output interval control to create flexible connection sections on the blades, enabling rigid wind turbine blades to be folded directly on-site at the wind farm. This compresses blades tens of meters long into folded bodies that meet the dimensions of standard truck beds, solving the problem that ultra-long composite material components cannot be transported as a whole machine. Meanwhile, the high energy density of the laser is used to vaporize the resin, ensuring the physical continuity of the glass fiber along its length and improving the reuse value of recycled glass fiber.

[0009] Furthermore, the step of performing independent heating control in the circumferential direction of the blades specifically includes: The blade circumferential direction is divided into multiple independently controlled partitions, each partition corresponding to a sector in the blade circumferential direction; By independently controlling the laser start / stop and power of each partition, 4 to 6 independent heating tracks are formed on the surface of the blade; The 4 to 6 independent heating trajectories are respectively distributed in the upper skin region, lower skin region, leading edge region, trailing edge region, and web region of the blade.

[0010] Through the above technical solution, multiple independent heating trajectories disrupt the original closed annular rigid body structure of the blade, decoupling the blade shell into multiple strips in the circumferential direction. In the subsequent bending process, the separated fiber bundles can undergo relative displacement, avoiding structural interference and stress concentration caused by the difference in curvature between the inner and outer sides, and ensuring that the blade can complete the folding action with a smaller radius.

[0011] Furthermore, the length of the pyrolysis section is 4 to 6 meters, and the length of the non-pyrolysis section is 0.5 to 1.2 meters.

[0012] Through the above technical solution, the length of the pyrolysis section directly matches the length and width limitations of the cargo box of conventional transport vehicles, while the length of the non-pyrolysis section provides sufficient bending allowance for the folding process. The alternating distribution of these two dimensions ensures that the final stacked structure meets logistics and transportation standards in terms of spatial volume, while preventing the flexible connection section from breaking under bending stress.

[0013] Furthermore, the process parameters for the intermittent laser heating are as follows: The power density of the laser is 8–20 W / cm². 2 The pyrolysis temperature is controlled at 500-600℃, and the laser heating speed along the blade axis is 0.5-5mm / s; During the intermittent laser heating process, the laser power and the speed of its movement along the blade axis are dynamically adjusted according to changes in blade thickness. In the middle region of the blade where the blade thickness is 20-30 mm, the moving speed is set to 1.5 mm / s, and the laser power is set to the reference power value. In the leaf root region where the blade thickness is 40–50 mm, the moving speed is set to 0.8–1.0 mm / s and the laser power is increased to 110%–130% of the reference power value; In the blade tip region where the blade thickness is 10-15 mm, the moving speed is set to 2.5 mm / s and the laser power is reduced to 60%-80% of the reference power value.

[0014] The above technical solution addresses the physical morphology of wind turbine blades, where the cross-sectional thickness gradually decreases from the blade root to the tip, by implementing dynamic matching of heat input. In the thick-walled region, the moving speed is reduced and the power is increased to provide sufficient heat energy to ensure complete decomposition of the deep resin; in the thin-walled region, the moving speed is increased and the power is reduced to prevent excessive heat concentration from damaging the fiberglass body strength, thus maintaining the consistency of pyrolysis processing quality across all blade sizes.

[0015] Furthermore, during the intermittent laser heating process, the pyrolysis chamber where the heating area is located is maintained at a negative pressure of -80 to -120 Pa, and nitrogen gas is introduced into the pyrolysis chamber to form a protective atmosphere, or a vacuum state is maintained.

[0016] The above technical solutions cut off the oxygen supply using inert gas or a vacuum environment, preventing the fibers and resins from undergoing oxidation and combustion reactions at high temperatures. The slight negative pressure ensures that the gaseous products generated by pyrolysis can only flow unidirectionally into the suction system, preventing toxic and harmful waste gases from escaping into the external environment.

[0017] Furthermore, the waste gas generated by the intermittent laser heating is treated sequentially through the following steps: Heavy tar with a boiling point greater than 200℃ is condensed through a first-stage condensation process at a temperature of 80±5℃. Light tar with a boiling point of 80 to 200℃ is obtained through two-stage condensation at a temperature of 0±2℃. Tar aerosols are removed by electrostatic capture; Volatile organic compounds are removed by catalytic combustion at a temperature of 600±50℃.

[0018] The above technical solution utilizes the temperature difference of staged condensation to achieve the physical separation and recovery of heavy tar and light tar. Then, an electrostatic field intercepts suspended droplets, and finally, catalytic combustion decomposes the remaining organic gaseous molecules. This step-by-step purification process achieves the resource-based classification and extraction of pyrolysis products and ensures environmentally compliant emissions of exhaust gases.

[0019] Furthermore, during the intermittent laser heating process, diffractive optical elements or microlens arrays are used to shape the laser beam, transforming the Gaussian-distributed laser beam into a flat-top distributed beam.

[0020] The above technical solution eliminates the defect of extremely high energy at the center and attenuation at the edge of the original laser beam. The flat-top beam spot ensures uniform heat distribution within the working area, preventing localized high temperatures at the center of the spot from burning through the glass fiber, while also avoiding insufficient heat at the edge of the spot that could lead to resin residue.

[0021] A second aspect of the present invention provides a field-intermittent laser pyrolysis recovery device for wind turbine blades, comprising: The annular shell is divided into an upper half-shell and a lower half-shell, which are used to wrap around the outside of the blade, and a hinge structure is installed between them; A mobile drive mechanism, mounted on the annular housing, is used to drive the annular housing to move along the blade axis; A laser array, circumferentially mounted along the inner wall of the annular housing, includes multiple laser emitters, and the laser array is divided into multiple circumferentially independently controlled partitions; The interval control unit is communicatively connected to the laser array and the moving drive mechanism, and controls the start and stop of the laser array according to the set length parameters, thereby forming alternating pyrolysis sections and non-pyrolysis sections in the blade length direction.

[0022] The above technical solution provides a mobile operating hardware that can operate directly in a field wind farm. The device uses the wind turbine blades as its travel track and, in conjunction with an interval control unit, automatically manages the output timing and displacement relationship of the heat source, eliminating the infrastructure costs of building large fixed reactors and realizing in-situ pyrolysis processing of ultra-large composite material components.

[0023] Furthermore, dynamic sealing components are provided at both ends of the annular shell; The dynamic sealing assembly includes an elastic floating mechanism, a floating block, and a sealing structure mounted on the floating block. The elastic floating mechanism is installed in the groove inside the annular housing and automatically expands and contracts with changes in the blade cross-section. The floating block is installed inside the elastic floating mechanism. The sealing structure, from the inside out, includes an inner metal brush seal for contacting the blade surface, a middle flexible graphite packing that fits the blade surface, and an outer air curtain sealing layer that forms a gas barrier.

[0024] Through the above technical solution, the sealing assembly can adapt to the surface curvature and dimensional differences at different positions of the blade by relying on the expansion and contraction of the elastic component. The metal brush is responsible for scraping off the adhering substances and completing the primary blocking, the graphite packing fills the surface gaps through pressure deformation, and the high-pressure air curtain forms an airflow blockage. The three-layer structure works together to maintain the sealed state of the pyrolysis chamber under dynamic moving conditions.

[0025] Furthermore, it also includes: The exhaust gas collection system includes a plurality of suction ports arranged circumferentially at both ends of the annular shell, wherein the number of suction ports at the upstream end is greater than the number of suction ports at the downstream end, thereby forming a directional airflow. The exhaust gas purification system, connected to the exhaust gas collection system, includes a primary condenser, a secondary condenser, an electrostatic precipitator, and a catalytic combustion device connected in sequence. A fiberglass collection device is located at the rear end of the annular housing and includes multiple rotating brush rollers, an annular scraper, and a negative pressure suction nozzle arranged corresponding to the independent heating trajectory. The intelligent control system includes a sensor array and a central controller, wherein the central controller dynamically adjusts the power of the laser array and the moving speed of the moving drive mechanism based on the data collected by the sensor array.

[0026] Through the above technical solutions, the asymmetrical arrangement of the suction port guides the pyrolysis waste gas to be discharged in a predetermined direction, thereby improving the negative pressure collection efficiency; the fiberglass collection device intervenes directly after the laser operation, using mechanical friction and negative pressure suction to peel off the carbonized particles remaining on the fiber surface, thereby improving the surface cleanliness of the recovered fiber; the intelligent control system constructs a closed-loop link between data acquisition and the execution mechanism, ensuring the process stability of the device when processing blade sections of different sizes.

[0027] This invention provides a method and apparatus for on-site intermittent laser pyrolysis recovery of wind turbine blades. It has the following beneficial effects: 1. This invention uses intermittent laser heating along the blade's length to create alternating pyrolytic and non-pyrolytic sections, while simultaneously controlling the heating along the circumferential direction to form multiple heating trajectories. This divides the original annular rigid body section into multiple independent fiber strips, allowing the blade to bend using the retained non-pyrolytic resin sections. The separated fiber strips fold and stack, significantly compressing the overall structural volume. This allows for the in-situ conversion of ultra-long components into foldable bodies that conform to conventional truck loading dimensions within the wind farm, directly solving the problem of oversized logistics transportation faced by wind turbine blades during decommissioning and recycling, and eliminating the need for traditional mechanical cutting processes.

[0028] 2. This invention achieves adaptive matching of heat input to different structural regions by dynamically adjusting laser power and movement speed based on blade thickness data through a central controller. Laser energy is used to increase heat input to thick-walled areas to ensure complete resin decomposition, while heat input is reduced to thin-walled areas to prevent thermal damage. This effectively removes resin while avoiding the high energy consumption associated with traditional fixed high-temperature kilns. This process fully preserves the physical continuity of the glass fiber along its length, maintaining its basic mechanical strength and ensuring the reuse value of the recycled material.

[0029] 3. This invention reduces the total amount of waste gas and tar generated through laser heating, thus lowering the load on the environmental protection system. Combined with a closed negative-pressure pyrolysis chamber and a stepped waste gas purification system, the waste gas undergoes physical graded condensation, electrostatic capture and interception, and catalytic combustion decomposition in sequence, achieving the classified recovery of liquid tar products and the compliant emission of gaseous pollutants. Furthermore, the mobile on-site operation device of this invention can directly utilize the power network provided by the wind farm for production operations, reducing the grid energy consumption cost of the recycling process and meeting the requirements of low-carbon and environmentally friendly resource utilization. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the device of the present invention; Figure 2 This is a schematic diagram of the folding of the interval pyrolysis blade of the present invention; Figure 3 This is a schematic diagram of multiple pyrolysis lines along the blade length direction of the present invention; Figure 4 This is a schematic diagram of the circumferential partitioning of the laser array of the present invention; Figure 5 This is a cross-sectional view of the dynamic sealing structure of the present invention; Figure 6 This is a schematic diagram illustrating the beam shaping principle of the present invention. Figure 7 This is a flow chart of the waste gas treatment system of the present invention; Figure 8 This is a diagram of the intelligent control system architecture of the present invention.

[0031] Figure 9 This is a diagram of the wind farm green electricity access system of the present invention.

[0032] Among them, 1. Annular shell; 2. Connecting and locking mechanism; 3. Blade; 4. Laser array; 5. Moving drive mechanism; 6. Dynamic sealing assembly; 61. Inner layer metal brush seal; 62. Middle layer flexible graphite packing; 63. Floating block; 64. Elastic floating mechanism; 65. Outer layer air curtain sealing layer. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Please see the appendix Figure 1 Appendix Figure 4 Appendix Figure 5 Appendix Figure 6 Appendix Figure 8 and attached Figure 9 The wind turbine blade on-site intermittent laser pyrolysis recovery device provided by this invention operates outside the wind turbine blade and is used to perform the aforementioned pyrolysis recovery method. The recovery device includes an annular shell 1, which has a split structure, divided into an upper half-shell and a lower half-shell. Specifically, it is fixed by a connecting locking mechanism 2 installed between the upper and lower half-shells. The connecting locking mechanism 2 includes a hinge structure and a locking mechanism, each installed on one side. The inner diameter of the annular shell 1 is set to a range of 1.5–3.0 meters, and the length is set to 2.0–3.0 meters to accommodate the physical space requirements of the wind turbine blade's variable cross-sectional profile from the blade root to the blade tip. A moving drive mechanism 5 is installed on the annular shell 1 to provide power for the annular shell 1 to move along the blade axial direction. This moving drive mechanism 5 uses 6–8 rubber drive wheels symmetrically arranged along the shell and is driven by a servo motor to achieve linear displacement at a predetermined speed. For the specific circuit and mechanical transmission structure of servo motor drive and speed control, those skilled in the art can use conventional electromechanical transmission control systems to implement it. Its electromechanical transmission design is a well-known technology in this field and will not be described in detail here.

[0035] A laser array 4 is mounted circumferentially on the inner wall of the annular shell 1. The laser array 4 consists of 16 to 24 laser emitters, which are semiconductor lasers or fiber lasers with a single-head power of 500W to 2kW and a total power of 30 to 80kW. Preferably, the lasers are semiconductor lasers with a wavelength of 980nm.

[0036] To ensure uniform heat input distribution, each laser emitter has a diffractive optical element or microlens array installed in its front-end optical path as a beam shaping element. The initial Gaussian-distributed laser beam is transformed into a flat-top beam with uniform energy distribution and an output spot size of 120mm × 60mm after passing through this beam shaping element, with a uniformity of approximately 92%.

[0037] The flat-top distributed beam eliminates the phenomenon of excessively high local energy in the center of the beam spot, preventing the composite material reinforcing fibers from breaking due to high temperature, and also avoids the phenomenon of incomplete resin decomposition caused by low energy at the edge of the beam spot.

[0038] The recovery device integrates a zone control unit and an interval control unit. The zone control unit divides the overall laser array 4 into multiple circumferentially independently controlled zones, each corresponding to a specific area around the wind turbine blade. Specifically, these zones are divided into 4 to 8 sections, corresponding to the upper skin area, lower skin area, leading edge area, trailing edge area, and web area of ​​the blade, respectively. like Figure 4 As shown, Zone 1 and Zone 5 correspond to the middle regions of the upper and lower skins of the blade, respectively. The structure of these regions is relatively flat and the thickness is uniform. The central controller controls the laser emitters in these two regions to output at standard power. Zones 2 and 8 correspond to the transition regions of the leading and trailing edges of the upper skin of the blade, respectively; zones 4 and 6 correspond to the transition regions of the leading and trailing edges of the lower skin of the blade, respectively. The material thickness of these transition regions is thinner than that of the middle of the skin. The central controller controls the laser power of these four regions to be reduced by 15% to 20% compared to the standard power. Zones 3 and 7 correspond to the leading and trailing edges of the blade, respectively. These two regions have large surface curvature and are prone to heat concentration. The central controller controls the laser power in these two regions to be reduced compared to the standard power to prevent local overheating in the blade edge region from causing fiber damage.

[0039] By differentiating the power distribution in the eight circumferential zones, heat input that matches the irregular cross-sectional characteristics of the blade is achieved, ensuring the consistency of resin vaporization degree in each independent heating trajectory on the same cross section.

[0040] During equipment operation, the partition control unit independently manages the power supply current and output power of the laser emitter in each partition according to the built-in partition power allocation logic, thereby creating multiple independent heating tracks extending longitudinally in parallel on the blade surface. Preferably, 4 to 6 independent heating tracks are set, corresponding to one track each on the upper skin, lower skin, leading edge, and trailing edge, and one track on each side of the web. The interval control unit adopts a programmable logic controller, which establishes a communication connection with the laser array 4 and the movement drive mechanism 5.

[0041] The interval control unit receives displacement data and sends a start or stop trigger command to the laser array 4 according to a preset length value, so that the laser continues to output or stops outputting within a set distance range, thereby creating alternating pyrolysis and non-pyrolysis sections along the longitudinal length of the blade.

[0042] For the control timing programming of programmable logic controllers, those skilled in the art can write corresponding control programs according to the set length parameters. The programming logic is well-known in the field and will not be elaborated here. To meet the energy consumption cost control requirements of on-site operations, the recovery device also integrates a green electricity access module to directly use the green electricity from the wind farm.

[0043] Specifically, the electricity generated by the first and second wind turbines in the wind farm is collected at the wind farm's step-up substation (10kV) and then connected to the green electricity access module via a direct connection line. The green electricity access module is equipped with a transformer (10kV / 306V) and a distribution cabinet. The high-voltage AC power is stepped down by the transformer and then input to the distribution cabinet for power distribution. One output of the distribution cabinet is connected to the laser power supply, providing high-frequency operating power for the laser array 4, the core of the system. The other output of the distribution cabinet is connected to a bidirectional inverter and then to a 200kW energy storage battery system to provide stable and reliable backup power for the entire recovery device during grid fluctuations or intermittent power outages.

[0044] During the pyrolysis reaction, dynamic sealing components 6 are installed at both ends of the annular shell 1 to prevent the gasified substances from diffusing into the external environment. Because the wind turbine blade has the geometric characteristics of continuously changing cross-sectional dimensions and curvature along the axial direction, the dynamic sealing component 7 adopts a deformation adaptive design that includes an elastic floating mechanism 64 and a three-layer sealing structure.

[0045] The elastic floating mechanism 64 is a telescopic assembly equipped with a spring or air bladder, with a telescopic stroke of ±50 to 90 mm. When the annular housing 1 moves to the area where the blade cross-sectional size increases, the outer surface of the blade presses outward against the three-layer sealing structure, forcing the elastic floating mechanism 64 to contract radially; when it moves to the area where the blade cross-sectional size decreases, the elastic floating mechanism 64 extends inward under its own restoring force, pushing the three-layer sealing structure to always adhere to the blade surface.

[0046] The elastic floating mechanism 64 is a spring element installed in a groove inside the annular housing 1. The inner end of the spring element is connected to the floating block 63, which is a rigid metal slider with a rectangular cross-section. When the annular housing 1 moves through the variable cross-section region of the blade, the floating block 63 transmits the spring force, with a travel range of ±50 to 90 mm. When moving to a region where the blade cross-section increases, the outer surface of the blade presses outward, forcing the floating block 63, along with the spring element, to retract radially into the groove; when moving to a region where the cross-section decreases, the spring element extends and pushes the floating block 63 to remain firmly inward.

[0047] The three-layer sealing structure, mounted on the floating block 63 and extending inward, is arranged sequentially from the innermost to the outermost layer as an inner metal brush seal 61, a middle flexible graphite packing 62, and an outer air curtain seal layer 65. The inner metal brush seal 61 is composed of Inconel 600 metal wire bundles, with bristles that directly contact the blade surface. The bristles are 20 mm long and adapt to the blade curvature through the flexible deformation of the metal wire bundles, scraping away residual deposits on the blade surface to perform the primary interception function.

[0048] The middle layer flexible graphite packing 62 is made of flexible graphite braided packing with a cross section of 10mm×10mm. It is physically deformed after being squeezed inward by the floating block 63 (rigid metal part) behind it, so as to closely fit the surface contour of the blade and cut off the gas leakage channel.

[0049] The outer air curtain sealing layer 65 is connected to an external air source. Nitrogen or carbon dioxide gas at a pressure of 0.2 MPa is injected into the sealing gap through annularly arranged air holes. The directional pressure airflow forms a gas barrier, blocking the final path of the trace amount of waste gas inside the pyrolysis chamber to overflow outward.

[0050] In addition, the device includes an intelligent control system comprising a sensor array and a central controller. The sensor array includes a 3D panoramic sensor, an infrared thermal imager, a pressure sensor, and a gas concentration sensor. The central controller is communicatively connected to the sensor array and is used to dynamically adjust the power of the laser array, the moving speed of the servo drive motor, and, based on the data collected by the sensor array, to regulate the suction flow rate of the exhaust gas collection system and the pressure of the air curtain seal by controlling a proportional valve, a mass flow meter, and a variable frequency fan, thereby ensuring that exhaust gas emissions meet standards.

[0051] Please see the appendix Figure 2 and attached Figure 3 This invention provides a method for on-site intermittent laser pyrolysis recycling of wind turbine blades, comprising: S1. Intermittent laser heating is performed along the blade surface in the blade length direction to form alternating pyrolysis and non-pyrolysis sections.

[0052] S2. During intermittent laser heating, independent heating control is performed in the circumferential direction of the blade, forming multiple independent heating tracks extending along the length direction on the blade surface, dividing the annular cross section of the blade into multiple independent fiber bundles.

[0053] S3. After pyrolysis, bend the blade along the unpyrolyzed section to separate and fold multiple independent fiber bundles, forming a layered structure.

[0054] During step S1, the laser pyrolysis device moves along the axial direction of the wind turbine blade and intermittently outputs laser energy according to the set spacing parameters. When the laser is continuously output, a pyrolysis section is formed. Within the pyrolysis section, the resin in the composite material absorbs the laser energy and undergoes pyrolysis and vaporization, exposing the internal reinforcing fibers and maintaining a physically continuous state.

[0055] When the laser output stops, the laser pyrolysis device continues to move through the area, forming an unpyrolyzed section. Within this section, the composite material does not undergo pyrolysis, and the resin components are retained. This unpyrolyzed section maintains the original physical properties of the composite material and is used as a flexible connecting section for subsequent folding processes.

[0056] When executing step S2, considering that the wind turbine blade body is a hollow variable cross-section structure, a multi-channel control method is used to manage the laser array surrounding the blade surface. The laser array is divided into multiple circumferential partitions, each partition corresponding to a specific sector in the circumferential direction of the blade.

[0057] By independently adjusting the laser power and on / off status of each zone, multiple independent heating tracks are formed on the blade surface. These independent heating tracks disrupt the original complete annular shell structure of the blade, dividing the annular section longitudinally into multiple independent fiber bundles.

[0058] During step S3, the pyrolysis-treated blade exhibits an alternating distribution of pyrolysis and non-pyrolysis sections, and the blade's circumferential direction has been transformed into multiple independent fiber bundles. A force is applied to cause the blade to bend 180 degrees along the non-pyrolysis section.

[0059] During the bending process, the fiber bundles located between the individual heating tracks undergo spatial separation. Each fiber bundle is bent independently along the unpyrolyzed section and overlaps with each other, ultimately forming a stacked structure with longitudinally compressed dimensions, thereby reducing the overall volume to meet the cargo box space requirements of standard transport vehicles.

[0060] Please see the appendix Figure 2 Appendix Figure 3 and attached Figure 8In the on-site intermittent laser pyrolysis recovery method for wind turbine blades of the present invention, the specific execution process of intermittent laser heating and the dynamic adjustment process of process parameters may include the following steps: S301. Set the spatial interval parameters for intermittent laser heating. Based on the cargo box space limitations of the transport vehicle and the required stacking height of the folded blades, set the length of the pyrolysis section to 4 to 6 meters. To ensure the bending radius of the blades during folding and to prevent fiber breakage during bending of the unpyrolysis section, set the length of the unpyrolysis section to 0.5 to 1.2 meters.

[0061] S302. Set the basic process parameters for intermittent laser heating. Control the laser power density between 8 and 20 W / cm². 2 Within the specified range, the pyrolysis temperature is maintained at 500–600℃, preferably 540–570℃. The moving drive mechanism is controlled to maintain the speed of the annular shell moving along the blade axis within the range of 0.5–5 mm / s. The intake air flow rate is precisely controlled by a proportional valve and a mass flow meter to introduce nitrogen gas with a purity greater than 99.9% into the pyrolysis chamber where the heating zone is located to form a protective atmosphere or maintain a vacuum state. Simultaneously, the operating frequency of the variable frequency fan, which acts as a suction device, is controlled to maintain the sealing pressure inside the pyrolysis chamber at a slightly negative pressure state of -80 to -120 Pa, preferably -100 Pa.

[0062] S303. Acquire three-dimensional morphological data and thickness variation data of the blade surface. The 3D panoramic sensor in the intelligent control system scans the outer surface of the blade in front in real time, establishes the blade cross-sectional profile model, and calculates the composite material thickness data at the current processing position.

[0063] S304. Dynamically adjust the process parameters of the variable cross-section region. The central controller receives the thickness change data and, according to its internally preset thickness-power-speed mapping table, synchronously adjusts the output power of the laser array in each circumferential zone and the operating speed of the moving drive mechanism. Wind turbine blades have the physical characteristic of large changes in cross-sectional thickness and curvature from the blade root to the blade tip; the specific adjustment logic is as follows: For the leaf root region, the composite material thickness in this region is 40–50 mm. The central controller instructs the laser power of the corresponding zone to be increased to 110–130% of the reference power value, preferably 120%, while simultaneously controlling the moving speed to be set to 0.8–1.0 mm / s. By reducing the moving speed and increasing the laser power, the heat input per unit area is increased, ensuring complete vaporization and decomposition of the deep, thick-walled resin.

[0064] For the central region of the blade, the composite material thickness is 20–30 mm. The central controller instructs the laser array to maintain a reference power value and controls the movement speed to be set to 1.5 mm / s.

[0065] For the blade tip region, the composite material thickness in this area is 10–15 mm. The central controller instructs the laser power of the corresponding zone to be reduced to 60–80% of the reference power value, preferably 70%, while simultaneously controlling the moving speed to increase to 2.5 mm / s. By increasing the moving speed and reducing the laser power, the heat input per unit area is reduced, preventing excessive heat concentration that could lead to a decline in the fiber physical properties of the thin-walled region.

[0066] S305. Monitor and implement closed-loop control of local pyrolysis temperature. Temperature distribution data of the laser-heated area surface is acquired in real time using an infrared thermal imager and fed back to the central controller. The central controller compares the actual temperature data with the set target temperature range of 500–600°C and fine-tunes the current of the corresponding laser emitter to stabilize the pyrolysis reaction process. For the acquisition of infrared temperature measurement signals and the execution of the closed-loop control algorithm, those skilled in the art can use conventional PID control algorithms, the process of which is well-known in the field and will not be elaborated upon here.

[0067] Please see the appendix Figure 2 and attached Figure 7 In the on-site intermittent laser pyrolysis recovery method for wind turbine blades of the present invention, the collection, purification, and folding verification process of the pyrolysis products may include the following steps: S401. During intermittent laser heating, the composite material vaporizes, generating waste gas containing tar and volatile organic compounds. The pyrolysis chamber is continuously evacuated by a waste gas collection system located at both ends of the annular shell. Multiple suction ports are circumferentially distributed at both ends of the annular shell. By setting the number of suction ports at the upstream end to be greater than the number at the downstream end, a directional airflow is formed inside the pyrolysis chamber. The suction flow rate parameters are controlled to maintain a negative pressure state of -80 to -120 Pa within the pyrolysis chamber, preventing internal waste gas from overflowing into the external environment.

[0068] S402. The exhaust gas discharged through the exhaust gas collection system is introduced into the exhaust gas purification system and undergoes four stages of physical and chemical treatment processes.

[0069] The exhaust gas enters the primary condenser, where it undergoes primary condensation at an operating temperature of 80±5℃. This process separates and collects the heavy tar with a boiling point greater than 200℃ from the exhaust gas, which is then stored and transported to a heavy tar tank.

[0070] The gas that has passed through the primary condensation process enters the secondary condenser, where it undergoes deep condensation at an operating temperature of 0±2℃. Light tar with a boiling point between 80 and 200℃ is separated and collected, and then stored and transported to a light tar tank.

[0071] The gas after condensation and oil removal is transported to an electrostatic precipitator. Under the action of a DC high-voltage electric field of 20-30kV, submicron-sized tar aerosols entrained in the gas are removed. The droplets adsorbed by electrostatics are collected in a fine tar tank. The removal efficiency of this step is greater than 98%.

[0072] The electrostatically collected gas enters the catalytic combustion device, where a catalytic oxidation reaction occurs at a temperature of 600±50℃, decomposing the remaining volatile organic compounds in the gas with a purification efficiency greater than 99%. After purification, the gas is monitored in real-time by gas concentration sensors in the intelligent control system. Once all indicators are confirmed to meet the requirements of GB 16297-2023 "Integrated Emission Standard for Air Pollutants," the gas is safely discharged or reused as a heat source in other on-site heating equipment.

[0073] S403. Behind the moving annular shell, a fiberglass collection device physically cleans and recovers the pyrolyzed fiber surface. Multiple rotating brush rollers and annular scrapers are mounted at the rear end of the annular shell. The installation positions of the rotating brush rollers correspond to multiple independent heating tracks on the blade surface. The rotating brush rollers and annular scrapers directly contact the fiber surface, peeling off resin residue adhering to the surface. The peeled solid material is then centrally sucked and collected through a configured negative pressure suction nozzle.

[0074] S404. After the overall pyrolysis of the blade is completed, the alternating pyrolysis sections and unpyrolysis sections form a bendable continuum. Taking a 1.5 MW wind turbine blade with a length of 30-40 meters as an example, its root section chord width is typically 2.5-3.0 meters, and the weight of a single blade is approximately 6-10 tons. Based on the aforementioned spatial spacing parameters, the length of a single pyrolysis section is 5 meters. Taking a blade with a length of approximately 32 meters as an example, initially, the blade contains a total of 6 pyrolysis sections along its entire length; unpyrolysis sections with a 1-meter interval between adjacent pyrolysis sections serve as connection points, resulting in a total of 5 unpyrolysis sections.

[0075] When an external force is applied to cause the blade to bend in space, each fiber bundle, separated by an independent heating trajectory, bends independently along the flexible, unpyrolyzed section and overlaps with each other. The final length of the folded structure depends on the sum of the length of the single pyrolyzed section and the bending allowance of the unpyrolyzed section, with the overall length ranging from 5 to 6 meters, and the folded length being approximately 5.5 meters.

[0076] The width of this stacked structure can be controlled within 2.4 meters after bending, extrusion, and shrinkage. Its stacking height corresponds to the thickness of the six pyrolysis sections stacked together, reaching approximately 3.0 meters. Since this height slightly exceeds the height limit of a standard cargo box, in actual operation, the number of hard sections is further adjusted to five, thereby controlling its stacking height within 2.5 meters.

[0077] The dimensions of this laminated structure are all matched to the internal cargo space constraints of a standard flatbed truck with a rated load capacity of 30 tons. After the above treatment, the total processing time for a single blade of this specification is approximately 6.5 hours, with a glass fiber recovery rate of over 91% and a fiber strength retention rate of over 81%; the gas production per ton of blade is approximately 70 cubic meters, and the tar content is approximately 13 g / m³. 3 All emissions ultimately meet environmental standards.

[0078] The process of loading the stacked structure into the vehicle cargo box can be accomplished by those skilled in the art using conventional lifting and hoisting machinery and binding and fixing methods. The hoisting and handling operation is a well-known technology in the field and will not be described in detail here.

[0079] To further verify the practical application effect of the aforementioned on-site intermittent laser pyrolysis recovery method and device for wind turbine blades, a specific test example is provided below. This test example verifies the on-site processing of a 1.5 MW wind turbine blade, which is approximately 32 meters long, has a root chord width of approximately 2.8 meters, a tip chord width of approximately 0.7 meters, and an overall weight of approximately 7.5 tons.

[0080] In terms of hardware configuration, the inner diameter of the annular shell used in the test was set to 2.5 meters to accommodate the variable cross-section requirements from the blade root to the blade tip. The length of the annular shell was 2.5 meters, and it was constructed using two halves connected by hinges. The laser array on the inner wall of the annular shell was equipped with 24 groups of semiconductor lasers with a wavelength of 980nm, each with a single-head power of 2.5kW and a total operating power of 60kW. Each laser emitter was equipped with a diffractive optical element as a homogenizer, capable of outputting a flat-top beam with a size of 120mm×60mm, and the energy distribution uniformity within the beam reached approximately 92%.

[0081] The dynamic sealing assemblies at both ends of the annular shell are mounted on the airbag floating mechanism with a telescopic stroke of ±70mm. Its three-layer sealing structure consists of an inner layer made of Inconel 600 metal wire with 20mm bristles, a middle layer of flexible graphite packing with a cross-sectional dimension of 10mm × 10mm, and an outer layer formed by introducing nitrogen gas at a pressure of 0.2MPa to create an air curtain seal. The moving drive mechanism uses six rubber friction wheels, driven by a servo motor for variable speed control, with a moving speed of 1.0mm / s at the root and 2.5mm / s at the tip.

[0082] In terms of operation control strategy, the partition control unit divides the laser array into 6 independent control areas in the circumferential direction, specifically including 2 upper skin partitions, 2 lower skin partitions, 1 leading edge partition and 1 trailing edge partition.

[0083] By independently adjusting the power of each zone, six independent heating tracks extending along the length of the blade surface are synchronously machined. The interval control unit sets the length of the pyrolysis section to 5 meters and the length of the non-pyrolysis section to 1.0 meter. The laser output is continuous during the processing in the pyrolysis section, and the laser is turned off when moving to the non-pyrolysis section, and the device moves through it rapidly at a speed of 3 mm / s. At the same time, the exhaust gas extraction system stabilizes the internal pressure of the pyrolysis chamber at -100±10 Pa.

[0084] During the specific processing, the recovery device moves continuously from the blade root towards the blade tip. The control system dynamically adjusts the processing parameters in real time, taking into account the gradual change in blade thickness. When passing through the blade root region where the composite material thickness is 40–50 mm, the laser output power is increased to 120% of the baseline value, and the moving speed is set to 0.8 mm / s; when passing through the middle region of the blade body where the thickness is 20–30 mm, the laser power remains at the baseline value, and the moving speed is set to 1.5 mm / s; when passing through the thin-walled blade tip region where the thickness is 10–15 mm, the laser power is reduced to 70% of the baseline value, and the moving speed is increased to 2.5 mm / s.

[0085] After the above-described operation, the total processing time for a single blade of this specification was approximately 6.5 hours. The test data showed excellent physical recycling performance, with a glass fiber recovery rate of approximately 91% and a fiber strength retention rate of approximately 81%.

[0086] In terms of environmental indicators, the gas production per ton of blades is approximately 70 cubic meters, and the tar content in the exhaust gas is approximately 13 g / m³. 3 After a four-stage purification process, the final concentration of volatile organic compounds in the emitted gas was 16 mg / m³. 3 The particulate matter concentration was 7 mg / m³. 3 All emission indicators meet the requirements of GB 16297-2023 "Integrated Emission Standard for Air Pollutants".

[0087] In the folding and transport verification phase, the processed blade was divided into six pyrolysis sections (totaling approximately 30 meters, with approximately 1 meter of edge allowance at each end) and five alternately distributed non-pyrolysis sections. An external force was applied to bend the non-pyrolysis sections, causing the six fiber bundles, separated by six independent heating paths, to fold independently, ultimately forming a laminated structure. The overall length of this laminated structure is approximately 5.5 meters, and its width shrinks to approximately 2.4 meters due to pressure at the blade root.

[0088] When all six pyrolysis sections are fully stacked, each section is approximately 0.5 meters thick, and the overall height is approximately 3.0 meters. Considering that the standard dimensions of a 30-ton flatbed truck cargo box are 13 meters long, 2.4 meters wide, and 2.7 meters high, to meet the height restriction, in practical applications, the bending allowance of the unpyrolysis sections can be appropriately compressed, or the number of pyrolysis sections can be reduced to five. This allows the final stacking height to be precisely controlled within 2.5 meters, achieving fully compliant loading.

[0089] Currently, a single operation can transport one processed blade. To further improve logistics loading efficiency, the length of a single pyrolysis section can be reduced to 4 meters to increase the number of folding layers, or multiple recycling devices can be used in parallel on-site.

[0090] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for on-site intermittent laser pyrolysis recovery of wind turbine blades, characterized in that, include: Intermittent laser heating is performed along the blade surface in the blade length direction to form alternating pyrolysis and non-pyrolysis sections. The resin in the pyrolysis section is pyrolyzed and vaporized, and the fibers are exposed. The non-pyrolysis section is not heated and the resin is retained as a flexible connection section. During the intermittent laser heating process, independent heating control is performed in the circumferential direction of the blade, forming multiple independent heating tracks extending along the length direction on the blade surface, dividing the annular cross section of the blade into multiple independent fiber bundles. After pyrolysis, the blade is bent along the unpyrolyzed section, causing the multiple independent fiber bundles to separate and fold independently, forming a layered structure, thus completing the recycling process.

2. The method for on-site intermittent laser pyrolysis recovery of wind turbine blades according to claim 1, characterized in that, The aforementioned independent heating control in the circumferential direction of the blades specifically includes: The blade circumferential direction is divided into multiple independently controlled partitions, each partition corresponding to a sector in the blade circumferential direction; By independently controlling the laser start / stop and power of each partition, 4 to 6 independent heating tracks are formed on the surface of the blade; The 4 to 6 independent heating trajectories are respectively distributed in the upper skin region, lower skin region, leading edge region, trailing edge region, and web region of the blade.

3. The method for on-site intermittent laser pyrolysis recovery of wind turbine blades according to claim 1, characterized in that, The length of the pyrolysis section is 4 to 6 meters, and the length of the non-pyrolysis section is 0.5 to 1.2 meters.

4. The method for on-site intermittent laser pyrolysis recovery of wind turbine blades according to claim 1, characterized in that, The process parameters for the intermittent laser heating are as follows: The power density of the laser is 8–20 W / cm². 2 The pyrolysis temperature is controlled at 500-600℃, and the laser heating speed along the blade axis is 0.5-5mm / s; During the intermittent laser heating process, the laser power and the speed of its movement along the blade axis are dynamically adjusted according to changes in blade thickness. In the middle region of the blade where the blade thickness is 20-30 mm, the moving speed is set to 1.5 mm / s, and the laser power is set to the reference power value. In the leaf root region where the blade thickness is 40–50 mm, the moving speed is set to 0.8–1.0 mm / s and the laser power is increased to 110%–130% of the reference power value; In the blade tip region where the blade thickness is 10-15 mm, the moving speed is set to 2.5 mm / s and the laser power is reduced to 60%-80% of the reference power value.

5. The method for on-site intermittent laser pyrolysis recovery of wind turbine blades according to claim 1, characterized in that, During the intermittent laser heating process, the pyrolysis chamber where the heating area is located is maintained at a negative pressure of -80 to -120 Pa, and nitrogen gas is introduced into the pyrolysis chamber to form a protective atmosphere, or a vacuum state is maintained.

6. The method for on-site intermittent laser pyrolysis recovery of wind turbine blades according to claim 1, characterized in that, The waste gas generated after intermittent laser heating is treated in the following steps: Heavy tar with a boiling point greater than 200℃ is condensed through a first-stage condensation process at a temperature of 80±5℃. Light tar with a boiling point of 80 to 200℃ is obtained through two-stage condensation at a temperature of 0±2℃. Tar aerosols are removed by electrostatic capture; Volatile organic compounds are removed by catalytic combustion at a temperature of 600±50℃.

7. The method for on-site intermittent laser pyrolysis recovery of wind turbine blades according to claim 1, characterized in that, During the intermittent laser heating process, diffractive optical elements or microlens arrays are used to shape the laser beam, transforming the Gaussian distributed laser beam into a flat-top distributed beam.

8. A field-mounted intermittent laser pyrolysis recovery device for wind turbine blades, used to implement the field-mounted intermittent laser pyrolysis recovery method for wind turbine blades as described in any one of claims 1-7, characterized in that, include: The annular shell (1) is divided into an upper half shell and a lower half shell, which are used to wrap around the outside of the blade (3). A hinge structure (2) is installed between the (1). A mobile drive mechanism (5) is mounted on the annular housing (1) and is used to drive the annular housing (1) to move axially along the blade (3); A laser array (4) is installed circumferentially along the inner wall of the annular housing (1) and includes multiple laser emitters. The laser array (4) is divided into multiple circumferentially independently controlled partitions. The interval control unit is connected in communication with the laser array (4) and the moving drive mechanism (5), and controls the start and stop of the laser array according to the set length parameters, thereby forming alternating pyrolysis sections and non-pyrolysis sections in the length direction of the blade (3).

9. A field-intermittent laser pyrolysis recovery device for wind turbine blades according to claim 8, characterized in that, The annular housing (1) is provided with dynamic sealing components at both ends; The dynamic sealing assembly (6) includes an elastic floating mechanism (64), a floating block (63), and a sealing structure mounted on the floating block (63). The elastic floating mechanism (64) is mounted in the groove inside the annular housing (1) and automatically expands and contracts with the change of the blade cross-section. The floating block (63) is mounted inside the elastic floating mechanism (64). The sealing structure, from the inside to the outside, includes an inner metal brush seal (61) for contacting the surface of the blade (3), a middle flexible graphite packing (62) that fits the surface of the blade, and an outer air curtain sealing layer (65) that forms a gas barrier.

10. A field-intermittent laser pyrolysis recovery device for wind turbine blades according to claim 8, characterized in that, Also includes: The exhaust gas collection system includes a plurality of suction ports arranged circumferentially at both ends of the annular housing (1), wherein the number of suction ports at the upstream end is greater than the number of suction ports at the downstream end, thereby forming a directional airflow. The exhaust gas purification system, connected to the exhaust gas collection system, includes a primary condenser, a secondary condenser, an electrostatic precipitator, and a catalytic combustion device connected in sequence. A fiberglass collection device is located at the rear end of the annular housing (1) and includes multiple rotating brush rollers, annular scrapers and negative pressure suction nozzles with corresponding independent heating trajectories. The intelligent control system includes a sensor array and a central controller. The central controller dynamically adjusts the power of the laser array (4) and the moving speed of the moving drive mechanism (5) based on the data collected by the sensor array.

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