Pyrolysis recovery system for cooperatively processing waste wind power blades by power station boiler

Abstract

The invention discloses a pyrolysis recovery system for cooperative treatment of waste wind power blades by a power station boiler, and belongs to the technical field of solid waste recovery. The system comprises a power station boiler, a pyrolyzing furnace, a mixed flue, a nitrogen air flue and a controller. Oxygen is accurately controlled by mixing flue gas at different temperature levels and mixing nitrogen, and a safe and stable heat source is provided for the pyrolyzing furnace; pyrolysis gas returns to a boiler hearth through an outlet flue to be burnt out, and recyclable fibers and residues are conveyed out through a chain grate stoker; and the controller is linked with each sensor to execute oxygen control, temperature regulation, fiber quality protection and safety interlocking operation. The problems that in pyrolysis of the waste wind power blade, heat source adaptability is poor, oxygen concentration is out of control, fiber quality is poor, the risk is high, and pyrolysis gas is difficult to dispose are solved, and gradient utilization of energy, intrinsically safe operation, high-quality and high-purity recovery of fibers and collaborative treatment of pollutants are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste recycling, and in particular to a pyrolysis recovery system for co-processing waste wind turbine blades with power station boilers. Background Art

[0002] With the rapid development of the wind power industry, a large number of wind turbine blades are entering retirement. These blades are primarily composed of glass fiber / carbon fiber reinforced resin-based composites, which offer high strength and corrosion resistance but are difficult to degrade naturally. Traditional disposal methods (landfill and incineration) pose challenges such as land occupation, environmental pollution, and resource waste. Fiber recovered through physical crushing suffers from severe performance degradation and low economic value. Pyrolysis can decompose resin in an oxygen-deficient environment to recover high-value fibers, but this requires a stable, high-temperature heat source and strictly controlled oxygen environment, otherwise it can easily cause explosions or degrade fiber quality.

[0003] At the same time, coal-fired power plant boilers generate large amounts of flue gas with varying temperatures, resulting in insufficient utilization of waste heat. Harnessing the waste heat from boiler flue gas to power blade pyrolysis could reduce pyrolysis energy consumption and improve power plant energy efficiency.

[0004] Existing technologies have numerous drawbacks, including poor heat source adaptability, large fluctuations in boiler flue gas temperature with load, and the inability of a single flue gas extraction system to consistently meet pyrolysis temperature requirements. Direct extraction of high-temperature flue gas can lead to decreased fiber strength, while extraction of low-temperature flue gas can result in incomplete pyrolysis, high resin residues, and inability to separate fibers. High flue gas oxygen content can also reduce fiber strength.

[0005] Existing standalone pyrolysis systems often rely on pure nitrogen to create an oxygen-free environment, which is costly and accounts for over 30% of the system's total energy consumption. Boiler flue gas mixing also lacks a dynamic oxygen regulation mechanism, leading to fluctuations in oxygen concentration that can exceed limits in certain areas, posing the risk of flash explosions.

[0006] Directly discharging concentrated pyrolysis gas pollutes the environment. Independent combustion disposal requires additional purification facilities, significantly increasing investment. Recycled fiber oxidizes and carbonizes when exposed to air during high-temperature transportation, and absorbs moisture and clumps during storage, reducing its reusability.

[0007] Therefore, there is an urgent need to develop a resource technology that can safely and efficiently utilize the waste heat of boiler flue gas to treat waste blades and achieve full process control of the product. Summary of the Invention

[0008] The present invention overcomes the problems of poor heat source adaptability, high risk of oxygen concentration out of control, and difficult disposal of pyrolysis gas in the pyrolysis of discarded wind turbine blades, and realizes energy cascade utilization, inherently safe operation, high-purity fiber recovery, and coordinated pollution control.

[0009] In order to achieve the above object, the present invention adopts the following scheme: The pyrolysis recovery system for waste wind turbine blades, which is coordinated with power station boilers, includes: A power station boiler is provided with a furnace, a horizontal flue, a turning chamber and a tail flue in the direction of flue gas flow. A pyrolysis furnace is provided with an inlet for waste wind turbine blades, an outlet for fibers, an inlet for flue gas, and an outlet for flue gas; The mixed flue has an outlet connected to the flue gas inlet of the pyrolysis furnace through a booster fan. The inlet of the mixed flue is connected to the high-temperature flue, the medium-temperature flue and the low-temperature flue. The inlet of the high-temperature flue is connected to the horizontal flue, the inlet of the medium-temperature flue is connected to the turning chamber, and the inlet of the low-temperature flue is connected to the tail flue; wherein, The high-temperature flue, medium-temperature flue and low-temperature flue are respectively equipped with closing dampers and regulating dampers, and the mixed flue is equipped with oxygen measurement points and temperature measurement points; A nitrogen air duct, the outlet of which is connected to the inlet of the mixing flue, and a regulating valve is provided in the nitrogen air duct; The flue gas outlet of the pyrolysis furnace is connected to the furnace of the power plant boiler through the pyrolysis furnace outlet flue. The pyrolysis furnace outlet flue is equipped with a gas analyzer. The pyrolysis furnace is equipped with a thermocouple and a chain grate for transporting waste wind turbine blades and fibers. The pyrolysis furnace is equipped with a visual monitoring device for observing the fiber removal situation. Flue gas purification equipment, whose flue gas inlet is connected to the rear of the tail flue of the power station boiler, including denitrification device, dust removal device and desulfurization device; The controller is respectively connected to the oxygen measurement point and temperature measurement point of the mixed flue, the regulating valve of the nitrogen air duct, the thermocouple of the pyrolysis furnace, the visual monitoring device, the drive motor of the chain grate, the gas analyzer and the power station boiler load monitoring device for communication signals, and controls the actuators of the high-temperature flue, the medium-temperature flue and the low-temperature flue regulating dampers through signals; the controller is configured to perform oxygen control, temperature regulation, fiber quality protection and safety control operations during the pyrolysis process.

[0010] Preferably, the oxygen measurement point of the mixing flue is a first oxygen measurement point, and a second oxygen measurement point is further provided at the flue gas inlet of the pyrolysis furnace. The controller obtains an initial oxygen signal of the flue gas at the first oxygen measurement point and a target oxygen signal of the flue gas at the second oxygen measurement point. Based on the initial oxygen signal of the flue gas and a preset target value of the oxygen range required for the pyrolysis reaction, and in combination with the real-time load status signal of the power plant boiler, the required nitrogen blending amount is calculated through a feedforward-feedback control algorithm. The controller generates and outputs a control signal to the regulating valve, dynamically adjusting its opening to add the calculated required nitrogen mixing amount into the mixed flue. When the oxygen value monitored by the second oxygen measurement point exceeds the upper limit of the preset oxygen range required for the pyrolysis reaction, the controller controls the opening of the regulating valve to increase to increase the nitrogen mixing amount; when the oxygen value monitored by the second oxygen measurement point is lower than the lower limit of the preset range, the controller controls the opening of the regulating valve to decrease to reduce the nitrogen mixing amount.

[0011] As a preference, the flue gas outlet of the pyrolysis furnace is provided with a venting pipe, which is connected to the atmosphere and installed with a shut-off valve. The gas analyzer monitors the combustible gas concentration in the flue gas at the pyrolysis furnace outlet in real time. When the power plant boiler is shut down and the system coordination needs to be released, the controller performs the following time sequence operations: Immediately close all closing dampers and regulating dampers on the high-temperature flue, medium-temperature flue, and low-temperature flue to cut off the flue gas heat source; open the main valve of the nitrogen air duct and adjust the regulating valve to the fully open state, and inject nitrogen into the mixed flue for purging; at the same time, open the shut-off valve of the vent pipe and close the damper connecting the pyrolysis furnace outlet flue to the boiler furnace, so that the purge gas is discharged to the atmosphere through the vent pipe; Continue to run the booster fan and monitor the gas analyzer data. When the combustible gas concentration is detected to be zero for 15 consecutive minutes, stop the booster fan. Wait until the chain grate has transported all the solid residues in the furnace and then stop the chain grate. Finally, close the regulating valve and main valve of the nitrogen air duct, and when the temperature difference between each temperature measuring point of the pyrolysis furnace and the ambient temperature is less than 5°C and maintained for 15 minutes, close the shut-off valve of the vent pipe.

[0012] Preferably, a thermocouple group and a flue gas distribution valve system are configured inside the pyrolysis furnace; at least three groups of thermocouples are arranged in parallel along the width of the furnace body in the central area and the edge areas on both sides of the pyrolysis furnace; the controller simultaneously receives the fiber desorption state image signal from the visual monitoring device and the temperature signal of the thermocouple group, and performs the following operations: An image recognition algorithm is used to extract visual characteristic parameters of the fiber surface, including color depth and texture edge displacement. If the color depth is higher than a set threshold, the target temperature setting inside the pyrolysis furnace is increased by 5-10°C. If the texture edge displacement per unit time is lower than a preset value, the chain grate speed is reduced by 10%-25% to extend the material residence time. Real-time comparison of the synchronous temperature data of each group of thermocouples along the width of the pyrolysis furnace. If the temperature detected by any thermocouple inside the pyrolysis furnace exceeds the preset temperature upper limit, the opening of the high-temperature flue gas branch valve in the corresponding area will be immediately reduced by 20%~30%, and the opening of the low-temperature flue gas branch valve will be simultaneously increased by 15%~25%; if the temperature does not drop below the preset upper limit by at least 20°C within 60 seconds, the high-temperature flue gas branch valve will be closed; if the temperature detected by any thermocouple inside the pyrolysis furnace exceeds the preset temperature lower limit, the opening of the low-temperature flue gas branch valve in the corresponding area will be immediately reduced by 20%~30%, and the opening of the high-temperature flue gas branch valve will be simultaneously increased by 15%~25%; if the temperature does not drop above the preset lower limit by at least 20°C within 60 seconds, the low-temperature flue gas branch valve will be closed; If the temperatures of all thermocouples do not exceed the upper and lower temperature limits, but the temperature difference between any two groups continues to be greater than 30℃ for 3 minutes, then open the high-temperature flue gas branch valve in the low-temperature area by 10%~15% and close the low-temperature flue gas branch valve by 5%~10%; close the high-temperature flue gas branch valve in the high-temperature area by 5%~10% and open the low-temperature flue gas branch valve by 8%~12%; recheck the temperature difference every 30 seconds until the temperature difference ΔT≤20℃ and stop adjusting.

[0013] Preferably, the controller receives in real time the flue gas inlet temperature T1 detected by the mixed flue temperature measuring point, the furnace temperature average T2 detected by the thermocouple in the pyrolysis furnace, and the oxygen concentration O measured by the second oxygen measuring point set on the flue gas inlet of the pyrolysis furnace; the controller calculates the real-time flue gas temperature T=0.6T1+0.4T2, and calculates the pyrolysis intensity factor K by weighted calculation based on the real-time flue gas temperature T and the oxygen concentration O. The calculation formula is: , where T ref is the median value of the predetermined optimal pyrolysis temperature, O ref is the median of the expected oxygen content, α and β are the temperature-dominant weight coefficients; Perform the following synchronous adjustment operations according to the pyrolysis intensity factor value: When the pyrolysis intensity factor is lower than the preset lower limit threshold, the opening of the medium-temperature flue damper is increased to increase the flue gas temperature, and the opening of the nitrogen duct regulating valve is reduced to increase the oxygen concentration; When the pyrolysis intensity factor is higher than the preset upper limit threshold, the opening of the medium-temperature flue damper is reduced to lower the flue gas temperature, and the opening of the nitrogen duct regulating valve is increased to reduce the oxygen concentration; If the flue gas temperature at the pyrolysis furnace outlet continues to deviate from the expected temperature range after adjustment, the opening of the regulating damper of the high-temperature flue or the low-temperature flue is adjusted at the same time.

[0014] Preferably, the controller receives the power plant boiler load signal in real time and performs the following operations: When the load change rate of the power plant boiler exceeds 3% / min for three consecutive minutes, the temperature weight coefficient α is dynamically modified based on the load change direction: When the load increases, the flue gas temperature weight coefficient α is increased to 1.2 times the original value; When the load decreases, the flue gas temperature weight coefficient α is reduced to 0.8 times the original value; Before the controller performs the synchronous adjustment operation according to the corrected pyrolysis intensity factor value, it verifies it through the temperature change rate of the thermocouple in the pyrolysis furnace. If the temperature change rate is inconsistent with the change direction of the pyrolysis intensity factor, the adjustment instruction is frozen and the manual intervention alarm is activated.

[0015] Preferably, the controller receives in real time the load signal of the power plant boiler and the temperature change rate data detected by the thermocouple in the pyrolysis furnace; when the boiler load change rate exceeds 5% / min for two consecutive minutes, it is determined to be a sudden load drop or a sudden load increase, and the following operations are performed: When the load drops suddenly, reduce the chain grate speed to 70% of the original speed to extend the residence time of the material inside the pyrolysis furnace; when the load rises suddenly, increase the chain grate speed to 130% of the original speed to shorten the residence time of the material inside the pyrolysis furnace; synchronously freeze the pyrolysis intensity factor calculation for 5 minutes, maintain the current flue gas adjustment damper and nitrogen valve opening unchanged; wait until the temperature change rate of the main thermocouple returns to within ±5℃ / min, reactivate the pyrolysis intensity factor calculation and release the speed freeze.

[0016] The present invention has at least the following beneficial effects: (1) through the deep integration of the boiler flue system and the pyrolysis furnace, a closed loop of step-by-step heat extraction, temperature control and pyrolysis gas backfire is constructed without the need for additional fuel supply; (2) by adopting dual oxygen measurement points and a feedforward-feedback algorithm, combined with nitrogen mixing and boiler load prediction, the oxygen concentration in the pyrolysis zone can be stably controlled, the fiber recycling quality can be enhanced and the inert gas consumption can be reduced; (3) the pyrolysis gas is burned out at high temperature in the boiler, and the pollutants can be efficiently removed by relying on the existing purification equipment; the shutdown sequence control ensures the safe exit of the system; (4) the pyrolysis process is dynamically optimized based on visual recognition and temperature zoning control, which significantly reduces the fiber carbon residue; (5) the pyrolysis intensity factor of multi-parameter fusion can achieve rapid response to variable load conditions and avoid reaction runaway. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the operating principle of the pyrolysis recovery system for co-processing waste wind turbine blades with a power station boiler provided by the present invention; Figure 2 It is a schematic structural diagram of a power station boiler according to the present invention. DETAILED DESCRIPTION

[0018] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0019] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0020] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the materials described are commercially available unless otherwise specified; in the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "set" should be understood in a broad sense, for example, they can be fixedly connected or set, or detachably connected or set, or connected or set as a whole. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. The orientations or positional relationships indicated by the terms "transverse", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0021] like Figure 1 and 2 As shown, the present invention provides a pyrolysis recovery system for co-processing waste wind turbine blades with a power station boiler, which includes: A power station boiler is provided with a furnace, a horizontal flue, a turning chamber and a tail flue in the direction of flue gas flow. A pyrolysis furnace is provided with an inlet for waste wind turbine blades, an outlet for fibers, an inlet for flue gas, and an outlet for flue gas; The mixed flue has an outlet connected to the flue gas inlet of the pyrolysis furnace through a booster fan. The inlet of the mixed flue is connected to the high-temperature flue, the medium-temperature flue and the low-temperature flue. The inlet of the high-temperature flue is connected to the horizontal flue, the inlet of the medium-temperature flue is connected to the turning chamber, and the inlet of the low-temperature flue is connected to the tail flue; wherein, The high-temperature flue, medium-temperature flue and low-temperature flue are respectively equipped with closing dampers and regulating dampers, and the mixed flue is equipped with oxygen measurement points and temperature measurement points; A nitrogen air duct, the outlet of which is connected to the inlet of the mixing flue, and a regulating valve is provided in the nitrogen air duct; The flue gas outlet of the pyrolysis furnace is connected to the furnace of the power plant boiler through the pyrolysis furnace outlet flue. The pyrolysis furnace outlet flue is equipped with a gas analyzer. The pyrolysis furnace is equipped with a thermocouple and a chain grate for transporting waste wind turbine blades and fibers. The pyrolysis furnace is equipped with a visual monitoring device for observing the fiber removal situation. Flue gas purification equipment, whose flue gas inlet is connected to the rear of the tail flue of the power station boiler, including denitrification device, dust removal device and desulfurization device; The controller is respectively connected to the oxygen measurement point and temperature measurement point of the mixed flue, the regulating valve of the nitrogen air duct, the thermocouple of the pyrolysis furnace, the visual monitoring device, the drive motor of the chain grate, the gas analyzer and the power station boiler load monitoring device for communication signals, and controls the actuators of the high-temperature flue, the medium-temperature flue and the low-temperature flue regulating dampers through signals; the controller is configured to perform oxygen control, temperature regulation, fiber quality protection and safety control operations during the pyrolysis process.

[0022] The basic heat source and flue gas source of the system is the power plant boiler. Figure 2 As shown, the boiler is sequentially arranged along the flue gas flow direction: a furnace, a horizontal flue, a turning chamber, and a tail flue. Fuel combustion in the furnace generates high-temperature flue gas. This high-temperature flue gas then flows through the horizontal flue (where heating surfaces such as superheaters are typically located, resulting in very high flue gas temperatures, potentially reaching 800-1000°C), the turning chamber (where the flue gas changes direction, reducing its temperature somewhat, but still within the medium-high temperature range, perhaps to 600-800°C), and the tail flue (where low-temperature heating surfaces such as low-temperature reheaters, low-temperature superheaters, and economizers are located, further reducing the flue gas temperature to a lower level, perhaps 300-400°C or lower). This structure naturally creates a significant temperature gradient from the boiler furnace outlet to the chimney outlet. This temperature gradient creates the conditions for providing flue gas heat sources of varying temperatures to the pyrolysis furnace. The boiler is the driving force and primary heat provider for the entire system.

[0023] The core processing unit for wind turbine blades is the pyrolysis furnace. It features four key interfaces: a waste wind turbine blade inlet (for inputting waste blades to be processed), a fiber outlet (for discharging fiber products recovered after pyrolysis), a flue gas inlet (for introducing heated flue gas), and a flue gas outlet (for discharging flue gas that has undergone heat exchange and carries pyrolysis products). The furnace is equipped with a chain grate for conveying waste wind turbine blades and fibers. The furnace also features thermocouples for temperature monitoring and a visual monitoring device (such as a high-temperature camera or observation window) for observing fiber removal. Pyrolysis is a process in the absence of or in the absence of oxygen, using thermal energy to decompose large organic molecules (such as the resin matrix in wind turbine blades) into smaller gases (pyrolysis gases), liquids (possibly smaller amounts of tar), fibers, and solid residues. The chain grate enables automated feeding and discharging. Thermocouples monitor the temperature at key locations within the furnace to ensure that the pyrolysis reaction occurs within a set temperature window (e.g., 500-600°C, the optimal range depending on the blade material). Visual monitoring devices are used to manually or automatically monitor the state and quality of fiber desorption from the blade substrate (e.g., whether there is excessive carbon residue, fiber sintering, etc.). The pyrolysis furnace is the core equipment for recycling waste blades. Waste blades are fed through the inlet and conveyed by the chain grate. They are indirectly or directly heated by the heated flue gas from the flue gas inlet, causing a pyrolysis reaction. The target product, fiber, is discharged through the outlet, and the pyrolysis gas produced by the reaction is discharged through the flue gas outlet along with the flue gas. Thermocouples and visual monitoring devices provide key signals for process monitoring and automatic control.

[0024] The system is designed with a mixing flue, the outlet of which is connected to the flue gas inlet of the pyrolysis furnace via a booster fan, providing it with power and the required hot flue gas. The inlet of the mixing flue is connected to three branch flues: a high-temperature flue (with its inlet connected to the boiler's horizontal flue), a medium-temperature flue (with its inlet connected to the boiler's turning chamber), and a low-temperature flue (with its inlet connected to the boiler's tail flue). Each branch flue (high-temperature, medium-temperature, and low-temperature) is equipped with a shutoff damper (for completely shutting off that flue gas) and an adjustment damper (for fine-tuning the flow of that flue gas). The mixing flue is equipped with an oxygen measurement point (the primary oxygen measurement point) and a temperature measurement point. The three branch flues draw flue gas of different temperatures from different parts of the boiler (the high-temperature flue provides the highest temperature flue gas, the medium-temperature flue provides the second highest temperature, and the low-temperature flue provides the lowest temperature flue gas). By adjusting the opening ratio of these three dampers, flue gases of different temperatures can be mixed as needed, resulting in a mixed flue gas flow with an adjustable temperature (for example, within a range of 500-700°C) at the outlet of the mixing flue. The dampers are closed for maintenance or emergency shut-off. The oxygen measurement point monitors the initial oxygen concentration of the mixed flue gas, and the temperature measurement point monitors the initial temperature of the mixed flue gas. The booster fan provides the pressure head required to overcome system resistance and feed the mixed flue gas into the pyrolysis furnace. This system cleverly utilizes the temperature gradient distribution of the boiler flue gas. By mixing flue gases at different temperatures, it provides a flexible, stable, and temperature-controllable heat source for the pyrolysis furnace. This is a key step in achieving "co-processing." The oxygen and temperature measurement points provide the initial signals for subsequent oxygen and temperature control.

[0025] The system features a nitrogen duct as a safety measure for nitrogen and oxygen levels. Its outlet is connected to the inlet of the flue gas mixing duct. A regulating valve is installed in the nitrogen duct to control the nitrogen flow rate. Nitrogen, an inert gas, is injected into the flue gas mixing duct and further mixed with the flue gas from the boiler, diluting the oxygen concentration in the flue gas. The pyrolysis process requires strict control of the oxygen content (typically well below 10%, for example, a target of 3-8% or lower) to prevent combustion or even explosion of pyrolysis products (especially pyrolysis gas) within the pyrolysis furnace. The opening of the regulating valve determines the flow rate of nitrogen, which directly affects the oxygen concentration of the mixed gas entering the pyrolysis furnace. The nitrogen duct is a core safety measure for ensuring pyrolysis safety (explosion prevention) and creating a suitable reaction environment (anoxic pyrolysis). It works in conjunction with the flue gas mixing duct to ensure that the heat carrier (flue gas + nitrogen) entering the pyrolysis furnace has an appropriate temperature and extremely low oxygen content. The regulating valve is a key actuator for precise oxygen concentration control.

[0026] The system is equipped with a booster fan to provide power for the mixed flue gas and nitrogen to enter the pyrolysis furnace and for the flue gas after pyrolysis to flow back to the power station boiler furnace, and to prevent ambient air from leaking into the pyrolysis furnace and its inlet flue, resulting in uncontrollable oxygen content.

[0027] The flue gas outlet from the pyrolysis furnace is connected back to the power plant's boiler furnace via a pyrolysis furnace outlet flue duct, forming a pyrolysis gas treatment and reuse pathway. A gas analyzer is installed on this outlet flue to monitor the composition of the post-pyrolysis flue gas, particularly the concentrations of combustible gases such as carbon monoxide (CO), hydrogen (H2), and methane (CH4). The flue gas discharged from the pyrolysis furnace carries combustible gases (pyrolysis gases) produced by the pyrolysis reaction. These gases have calorific value. The gas analyzer monitors their composition and concentration in real time, providing a basis for process monitoring and safety control. Returning this combustible gas-rich flue gas to the boiler furnace allows it to be completely combusted in the high temperature environment of the boiler. This not only recovers the energy contained in the flue gas, improving overall system energy efficiency, but also completely eliminates the safety hazards and environmental pollution risks of direct combustible gas emissions (by preventing VOC emissions). This is another important manifestation of "co-processing" (energy synergy). This design ensures safe and efficient treatment and energy recovery of pyrolysis gas. Gas analyzers are not only used for energy assessment, but also serve as important input signals for safety interlock controls (for example, detecting abnormally high concentrations of combustible gas may trigger safety measures).

[0028] The system includes standard flue gas purification equipment as the tail flue gas purification system. The flue gas inlet of the flue gas purification equipment is connected to the tail flue of the power plant boiler (i.e., the original flue flow of the boiler). The purification equipment usually includes a denitrification device (such as SCR, which is used to remove nitrogen oxides NO x ), dust removal equipment (such as electrostatic precipitators or bag filters, used to remove fly ash particles) and desulfurization equipment (such as wet desulfurization, used to remove sulfur dioxide SO2). This is a standard environmental protection configuration for coal-fired / biomass boilers, used to purify the flue gas produced by boiler combustion so that it meets emission standards. In this collaborative system, the boiler burns fuel and reinjected pyrolysis gas, and the flue gas produced must still be treated by this set of purification equipment to meet the standards before it can be discharged. This set of equipment ensures that the final flue gas emitted by the entire system (including the collaborative treatment part) is clean and meets the requirements of environmental regulations. It processes all flue gases coming out of the boiler's tail flue, which contains pollutants produced by burning fuel and pyrolysis gas.

[0029] The system's central controller is connected via communication lines to the following equipment and signal points: the oxygen measurement point in the mixing flue (the primary oxygen measurement point), the temperature measurement point in the mixing flue, the regulating valve in the nitrogen duct, the thermocouples in the pyrolysis furnace, the visual monitoring device for the pyrolysis furnace, the gas analyzer in the pyrolysis furnace outlet flue, and the load monitoring device for the power plant's boilers. The controller also controls the actuators (i.e., the devices that adjust the damper openings) in the high-temperature, medium-temperature, and low-temperature flues via signal lines. The controller is programmed to perform key control operations during the pyrolysis process, including oxygen control (maintaining a safe low-oxygen environment), temperature regulation (ensuring pyrolysis within the optimal temperature range), fiber quality protection (preventing fiber overheating and damage or inadequate pyrolysis), and safety control operations (such as emergency shutdown and purge). The controller is the control center of the entire system and the core of automated control. It collects real-time signals from various measurement points (oxygen content, temperature, combustible gas concentration, boiler load, fiber image, furnace temperature distribution, etc.), performs calculations and analysis based on preset control logic and algorithms (which may include feedback control, feedforward control, logical judgment, etc.), and then outputs control instructions to actuators (such as nitrogen control valves and flue damper actuators). The controller is the key to the coordinated, safe, and efficient operation of all the above technical features. It implements functions such as oxygen control, temperature regulation, fiber quality protection, and safety control, including: Oxygen control: Dynamically adjust the nitrogen valve opening based on the measurement point signal to ensure that the oxygen concentration of the mixed gas entering the pyrolysis furnace is at a safe level that is conducive to pyrolysis.

[0030] Temperature regulation: Based on the temperature measurement point signal and boiler load status, the opening ratio of the three-way flue dampers is dynamically adjusted to control the temperature of the mixed flue gas and thus the temperature of the pyrolysis furnace.

[0031] Fiber quality protection: The temperature distribution in the furnace is monitored by thermocouples (to prevent local overheating and reduce fiber quality), and the fiber desorption status is assisted by a visual monitoring device (indirectly reflecting the degree of pyrolysis).

[0032] Safety control: Receives boiler load signals (sudden load changes may affect flue gas parameters) and can execute preset safety interlock procedures (such as emergency cutting off of heat source, nitrogen injection for purging) under abnormal conditions (such as excessive combustible gas concentration, boiler shutdown).

[0033] As an example of system operation, during system startup, based on the current boiler load and pre-set initial parameters, the controller commands the opening of the corresponding flue dampers and regulating dampers (for example, primarily opening the medium-temperature flue) and adjusts the openings to their initial positions. Simultaneously, the booster fan is turned on. The nitrogen regulating valve is also opened to its initial opening. Waste blades are added. The controller continuously reads signals such as the mixed flue oxygen content and temperature, multiple temperatures within the pyrolysis furnace, outlet combustible gas concentration, and boiler load. If the mixed flue oxygen content exceeds the set value, the controller increases the nitrogen valve opening for dilution. If the temperature in a particular area of ​​the pyrolysis furnace falls below the set value, the controller increases the regulating dampers in the high-temperature or medium-temperature flues (or decreases the dampers in the low-temperature flue) to increase the proportion of high-temperature flue gas. If visual monitoring indicates signs of fiber carbonization, the controller may increase the target oxygen content or temperature setpoint or reduce the chain speed. If a sudden decrease in boiler load causes the flue gas temperature to drop, the controller quickly adjusts the damper opening and may also adjust the nitrogen flow rate to maintain pyrolysis conditions. The entire process is a dynamic closed-loop continuous control process.

[0034] This system fully utilizes flue gas at varying temperatures from power plant boilers as a pyrolysis energy source, achieving cascaded energy utilization and significantly reducing the operating costs of pyrolysis recycling of discarded wind turbine blades. Through precise oxygen control (nitrogen blending), multiple monitoring mechanisms (temperature, combustible gas, and visualization), and a designed safe path for pyrolysis gas backfires into the boiler, it effectively prevents fires and explosions during the pyrolysis process, ensuring the safety of personnel and equipment. Multi-point temperature monitoring, visualization, and chain grate speed control optimize pyrolysis reaction conditions, helping to improve the purity (reducing carbon residue) and physical properties (preventing overheating that reduces fiber strength) of the recycled fiber. The combustible gases generated by pyrolysis are introduced into the boiler's high-temperature furnace for thorough combustion. The pollutants, along with the boiler flue gas, are treated in sophisticated and efficient denitrification, dust removal, and desulfurization equipment at the tail end, ensuring that final emissions meet stringent environmental standards. The integrated control system automates the monitoring and control of key parameters of the pyrolysis process (oxygen content, temperature, and fiber state-related parameters), significantly reducing the difficulty and intensity of manual operations and improving system stability and processing efficiency. The waste blade processing facilities were deeply integrated with the existing power plant boiler system, sharing the heat source (flue gas), energy recovery facilities (boiler furnace) and environmental protection facilities (tail purification), thus achieving efficient utilization of infrastructure.

[0035] The hybrid flue system (including high-temperature, medium-temperature, and low-temperature flues and baffles) combines nitrogen ducts and regulating valves, with a controller for coordinated control of oxygen content and temperature. This design enables the safe, stable, and flexible supply and control of a heat carrier that meets the pyrolysis process requirements (specific temperature, extremely low oxygen content) when utilizing the heat of boiler flue gas for pyrolysis. To further illustrate the effectiveness of this technology, an example is provided: The scenario involves a 350MW coal-fired power plant boiler co-processing discarded wind turbine blades. The boiler is operating at 50% load.

[0036] The operation process includes: 1. The controller receives the target instruction: the main pyrolysis section of the pyrolysis furnace needs to maintain 580±20℃, and the oxygen content of the inlet flue gas needs to be controlled at 5-7% (vol).

[0037] 2. The controller reads the signal in real time: Mixed flue gas temperature measurement point: Current mixed flue gas temperature is 520°C. Mixed flue gas oxygen measurement point (first oxygen measurement point): Current oxygen content is 8% (from the boiler flue gas itself). Boiler load monitoring: Stable at 50%.

[0038] 3. Oxygen Control: The controller determines that the current mixed flue gas oxygen content (8%) is higher than the target upper limit (7%). It uses an algorithm to calculate the amount of nitrogen required and outputs a signal to increase the opening of the nitrogen duct control valve. Nitrogen is injected into the mixed flue gas inlet, where it mixes and dilutes with the boiler flue gas. The controller continuously monitors until the oxygen content at the mixed flue gas outlet (or the second oxygen measurement point at the pyrolysis furnace inlet) drops to 5.8%, stabilizing within the target range.

[0039] 4. Temperature Control: The controller determines that the current mixed flue gas temperature (520°C) is slightly below the target median (580°C). Using an algorithm, it fine-tunes the dampers in each flue: slightly opening the high-temperature flue damper (increasing the proportion of high-temperature flue gas above 700°C) and slightly closing the low-temperature flue damper (reducing the proportion of low-temperature flue gas by approximately 300°C). The damper opening in the medium-temperature flue remains roughly constant. The mixed flue gas temperature rises to 590°C, meeting pyrolysis requirements.

[0040] 5. Pyrolysis Operation: A precisely controlled mixed gas with a temperature of approximately 590°C and an oxygen content of approximately 5.8% is fed into the pyrolysis furnace by a booster fan. This mixture serves as a heat source to heat the discarded wind turbine blades, resulting in a safe and efficient pyrolysis reaction. The combustible gases produced by the pyrolysis are returned to the boiler furnace for combustion.

[0041] The system's controller dynamically coordinates the nitrogen blending amount and the ratio of the three flue gases when the boiler load fluctuates (e.g., rising to 90% or falling to 70%) or flue gas parameters vary naturally from different locations. The pyrolysis furnace inlet consistently provides a heat carrier with stable temperature (minimal fluctuations) and strictly controlled oxygen content, ensuring a safe (no risk of explosion), continuous (stable temperature facilitates reaction), and efficient (high-quality fiber recovery and stable pyrolysis gas production) The boiler's waste heat is used for pyrolysis in a cascaded and precise manner, eliminating the need for additional fuel.

[0042] According to the common method in the prior art, only a single boiler flue gas source is used without mixing and dynamic oxygen control. A corresponding comparative example is provided: The scenario assumes a 350MW, 50%-load utility boiler is attempting to process discarded wind turbine blades. Flue gas is extracted from the boiler's horizontal flue (the high-temperature section, approximately 720°C) and fed directly into a modified pyrolysis furnace via a simple fan without any mixing or oxygen regulation.

[0043] During operation, the initial flue gas temperature is approximately 720°C, with an oxygen content of approximately 7-8%. A flue gas temperature of 720°C accelerates the pyrolysis reaction for many composite materials, and an initial flue gas oxygen content of 7-8% is already high. Within the pyrolysis furnace, when the pyrolysis reaction begins to release large amounts of combustible gases (such as H₂, CO, and CH₄), the oxygen concentration in localized areas can easily reach the explosive limit. At some point during the pyrolysis process, high concentrations of hydrogen (H₂) may form in localized areas within the furnace due to material accumulation or uneven temperatures. At this point, the oxygen content in this area (still close to 7-8%) combined with the H₂ concentration reaches the lower explosion limit of H₂ (approximately 4% in air). This, combined with a high-temperature hotspot or static spark, can instantly trigger a localized flash explosion or deflagration. Accumulated risks can lead to: internal damage to the pyrolysis furnace (furnace lining, temperature measuring elements, sight glasses, etc.); fires that damage the processed materials or recycled fibers; emergency shutdowns resulting in production interruptions and safety accidents; and damage to the pyrolysis gas pipeline, causing flammable gas leaks and creating secondary risks. Even if an explosion does not occur, high oxygen content can cause some pyrolysis products (especially tar and some gases) to undergo partial oxidation and combustion within the furnace, rather than pure pyrolysis. This can cause the target recycled fibers to be ablated or contaminated, further degrading their quality. The expected pyrolysis gas yield and composition become unstable, with large fluctuations in calorific value, making effective recycling difficult. It also makes furnace temperature control even more difficult (oxidation exotherm interferes with the pyrolysis endotherm).

[0044] This alternative fails to address the core challenges of safe and efficient pyrolysis using boiler flue gas. Its fatal flaws include uncontrollable temperature (a single low-temperature source leads to incomplete pyrolysis) and uncontrollable oxygen levels (a high-oxygen environment creates serious safety hazards and side reactions). This approach not only fails to achieve safe and effective recycling of spent blades, but also introduces significant safety risks (explosion) and operational instability, resulting in equipment damage and production interruptions, making its economic and safety performance extremely poor.

[0045] Comparison of the examples with the comparative examples clearly and intuitively demonstrates that the key technology of the present application, namely the coordinated regulation of a mixed flue system + nitrogen duct + controller, safely, stably, and flexibly utilizes fluctuating boiler hot flue gas (of varying temperatures and oxygen content) to provide a suitable (specific temperature, extremely low oxygen) heat carrier for pyrolysis. This overcomes the inability of existing technologies (such as the simple extraction of a single flue gas in the comparative examples) to provide a suitable pyrolysis temperature. By mixing flue gases at different temperatures, a wide range of flexible and stable temperature adjustments is achieved. More importantly, this overcomes the existing problems of low fiber quality, significant safety hazards (deflagration, explosion), and side reactions (oxidative combustion) caused by the inability to control oxygen levels. Through precise nitrogen blending and closed-loop control, the oxygen level is strictly controlled to a level that maximizes fiber value and ensures safe operation, thus ensuring fiber quality and the inherent safety of the pyrolysis process. The coordinated control of the mixed flue system and the nitrogen duct makes it possible to use the complex and changeable flue gas conditions of power station boilers for safe, efficient and continuous pyrolysis recovery, realizing true "synergistic" value. This is an important breakthrough in this application. In comparison, the existing technology is not feasible in terms of safety and effectiveness in using boiler flue gas for blade pyrolysis.

[0046] The booster fan provides power for the mixed flue gas and nitrogen to enter the pyrolysis furnace and for the flue gas after pyrolysis to flow back to the power plant boiler furnace, and prevents ambient air from leaking into the pyrolysis furnace and its inlet flue, which would cause uncontrollable oxygen levels. To further analyze the effect of this technology, an example is provided: The scenario is a 350MW power plant boiler co-processing discarded wind turbine blades. The pyrolysis furnace is operating normally, with the internal temperature stable at approximately 580°C.

[0047] The specific process includes: 1. Generation of pyrolysis gas: The resin matrix in the wind turbine blades is cracked in the high-temperature, oxygen-deficient environment of the pyrolysis furnace, producing a mixed gas whose main components are hydrogen (H2), carbon monoxide (CO), methane (CH4), a small amount of other hydrocarbons and carbon dioxide (CO2), namely pyrolysis gas.

[0048] 2. Pyrolysis Gas Transportation and Monitoring: Pyrolysis gas, along with the heat-carrying flue gas, is discharged from the pyrolysis furnace flue gas outlet and directed through the pyrolysis furnace outlet flue into the power plant boiler furnace. A gas analyzer installed in the flue gas outlet, just before entering the boiler furnace, continuously monitors flue gas composition online, displaying key data such as hydrogen, carbon monoxide, methane, carbon dioxide, oxygen, and nitrogen concentrations in real time.

[0049] 3. Safe Backfire and Energy Recovery: Mixed flue gases containing combustible gases are injected directly into the boiler furnace. The furnace is the hottest area in the boiler (typically well over 1000°C) and contains abundant combustion air and turbulent mixing conditions. Pyrolysis gases are instantly ignited and completely burned here.

[0050] Safe elimination: High temperature and sufficient residence time ensure that all combustible components (H2, CO, CH4, etc.) are completely oxidized and decomposed, eliminating the risk of their accumulation and reaching the explosion limit downstream of the pyrolysis furnace or in separate exhaust pipes.

[0051] Energy recovery: The heat released by the combustion of pyrolysis gas is directly fed into the boiler's steam generation system, improving the boiler's overall thermal efficiency. This is equivalent to recovering part of the chemical energy in the waste blades for power generation.

[0052] Environmental protection disposal: Pollutants generated by pyrolysis gas combustion (mainly NO x The flue gas (containing 100% nitrous oxide, 0.1% nitrous oxide, and very low levels of particulate matter) is combined with the flue gas generated by the combustion of the boiler's main fuel and then enters the high-efficiency flue gas purification equipment (denitrification, dust removal, and desulfurization) installed at the rear of the boiler for treatment, ultimately achieving standard emissions. Gas analyzer data is also used to assess pyrolysis efficiency and energy recovery benefits.

[0053] This design achieves high-quality fiber recovery, intrinsically safe disposal of pyrolysis gas (instantaneous combustion in a controlled, high-temperature environment), efficient energy recovery (leveraging existing boiler facilities, eliminating the need for additional combustion equipment), and environmentally compliant emissions (relying on a proven purification system). Gas analyzers provide critical safety monitoring (confirming low oxygen levels and the absence of abnormally high concentrations of combustibles) and support process optimization.

[0054] According to the common methods in the prior art, the pyrolysis gas is not backfired into the boiler or is simply discharged / treated. A corresponding comparative example is provided for this situation: The scenario is set as an independent waste wind turbine blade pyrolysis plant (not coordinated with a power station boiler).

[0055] During operation, three pyrolysis gas disposal solutions are provided, including: Pyrolysis gas disposal option A (flare combustion): The plant passes pyrolysis gas through a high-altitude flare for combustion. The calorific value of the pyrolysis gas is completely wasted in the atmosphere, failing to be recycled and reused, resulting in poor operating economics. The flare is affected by fluctuations in wind speed, air pressure, and gas composition, which can lead to incomplete combustion, producing black smoke (carbon particles), carbon monoxide (CO), and unburned volatile organic compounds (VOCs), causing air pollution and potentially violating environmental regulations. The continuously burning flare produces significant light pollution and noise, adversely affecting the surrounding environment. Open flame systems themselves pose certain safety concerns.

[0056] Pyrolysis gas disposal plan B (emission after simple purification): The factory attempts to simply cool and filter the pyrolysis gas, and then discharge it directly through the chimney. Pyrolysis gas contains flammable gases. Once it mixes with air in the emission pipe or chimney and reaches the explosion limit, a spark (static electricity, equipment friction, etc.) can cause a catastrophic explosion. This is an extremely dangerous operation. Directly discharging pyrolysis gas without combustion treatment means directly discharging a large amount of hydrogen, carbon monoxide, methane, and VOCs (toxic and harmful volatile organic compounds) into the atmosphere. This not only causes greenhouse gas (methane) emissions, but also forms photochemical smog precursors (VOCs, NO x This can be accompanied by severe environmental pollution, which inevitably violates the strictest environmental regulations and risks substantial fines and closure. Some pyrolysis products can be odorous or toxic (such as organic compounds containing nitrogen, sulfur, and chlorine), and their direct release can impact the health and quality of life of nearby residents.

[0057] Pyrolysis gas disposal option C (independent small combustion furnace): The plant configures a dedicated small combustion furnace for incineration of pyrolysis gas. This requires additional investment in the construction of the combustion furnace, a supporting fuel supply (which may require auxiliary fuel ignition and stable combustion), an air supply system, high-temperature resistant materials, and independent flue gas purification equipment (denitrification, dust removal, etc.), significantly increasing investment and operating costs. This combustion purification system requires independent operation and maintenance, adding operational complexity. Small combustion furnaces typically have lower thermal efficiency than large power plant boilers, resulting in poor energy recovery. Due to the small scale of the flue gas purification system, its treatment efficiency and stability may also be inferior to those of mature systems in large power plants. Pyrolysis gas production fluctuates with blade throughput, and small combustion furnaces struggle to quickly and stably match these fluctuations, potentially leading to frequent starts and stops or unstable combustion (low efficiency and poor emissions).

[0058] As can be seen, existing technologies (whether using flares, direct exhaust, or standalone combustion furnaces) for treating pyrolysis gas all present serious safety hazards (explosion), environmental pollution risks (VOCs, CO, greenhouse gases, etc.), energy waste, and / or high additional investment and operating costs. While standalone small combustion furnaces can address safety and some pollution issues, their economic efficiency and efficiency are far lower than the solution proposed in this application.

[0059] Comparison of the Examples and Comparative Examples clearly demonstrates that the key technical feature of this application, connecting the pyrolysis furnace flue gas outlet to the power plant boiler furnace and installing a gas analyzer in the outlet flue, achieves the crucial effect of safely, environmentally friendly, and economically disposing of the flammable, explosive, and polluting combustible gases generated during the pyrolysis process. Leveraging the inherent advantages of existing power plant boilers—the ultra-large capacity, ultra-high temperature, extremely turbulent mixing, and comprehensive purification facilities—this approach provides the most reliable and thorough destruction (combustion) environment for pyrolysis gas, inherently and safely eliminating the risk of explosion. This achieves efficient recovery of the chemical energy of the pyrolysis gas (improving boiler efficiency) and significantly improves the economic efficiency of the entire coordinated treatment system. This ensures that pollutants derived from the pyrolysis gas are properly treated through the boiler's mature, efficient, and large-scale post-processing system, avoiding secondary contamination. The gas analyzer provides critical real-time safety monitoring (confirming low oxygen levels and the absence of abnormalities) and process optimization data. With the existing technology shown in the Comparative Examples, pyrolysis gas disposal would become a significant technical, safety, environmental, and economic bottleneck for independent pyrolysis plants, potentially rendering the entire project unfeasible. This application proposal cleverly achieves deep coordinated operation between waste resource processing and large-scale energy infrastructure.

[0060] In another technical solution, the oxygen measurement point in the mixing flue is the first oxygen measurement point, and a second oxygen measurement point is provided at the flue gas inlet of the pyrolysis furnace. The controller obtains the initial flue gas oxygen signal at the first oxygen measurement point and the target flue gas oxygen signal at the second oxygen measurement point. Based on the initial flue gas oxygen signal and the preset target oxygen range required for the pyrolysis reaction, combined with the real-time load status signal of the power plant boiler, the required nitrogen blending amount is calculated using a feedforward-feedback control algorithm. The controller generates and outputs a control signal to the regulating valve, dynamically adjusting its opening to add the calculated required nitrogen mixing amount into the mixed flue. When the oxygen value monitored by the second oxygen measurement point exceeds the upper limit of the preset oxygen range required for the pyrolysis reaction, the controller controls the opening of the regulating valve to increase to increase the nitrogen mixing amount; when the oxygen value monitored by the second oxygen measurement point is lower than the lower limit of the preset range, the controller controls the opening of the regulating valve to decrease to reduce the nitrogen mixing amount.

[0061] The system features a first oxygen measurement point in the mixing flue (for initial oxygen monitoring) and a second oxygen measurement point at the pyrolysis furnace flue gas inlet (for target oxygen monitoring). The controller synchronously receives the boiler's real-time load signal (e.g., 50% or 75% operating status) and combines this with a preset target oxygen range for the pyrolysis reaction (e.g., 4%-7%). The first measurement point detects the initial oxygen content of the boiler flue gas, while the second measurement point monitors the actual oxygen content after nitrogen addition, which is the target oxygen content. The controller utilizes a feedforward-feedback hybrid algorithm. The feedforward portion predicts flue gas flow changes based on boiler load (e.g., flue gas oxygen decreases as load increases), while the feedback portion compares the data from the second measurement point with the target range in real time. The target oxygen range can be set from 4% to 7% (the ideal oxygen level for high-value glass fiber recovery). A preset upper limit of 7.5% triggers nitrogen addition, while a lower limit of 6.5% stops nitrogen addition.

[0062] During dynamic nitrogen regulation, the initial state is: 50% boiler load, 8% oxygen at the first measuring point, and a target oxygen level of 6.5%. Feedforward calculation: When the load increases to 75%, the flue gas oxygen level is predicted to drop to 5%, and the controller pre-decreases the nitrogen valve opening to 5%. Feedback correction: When the second measuring point shows an oxygen level of 4.5% (close to the lower limit of 4%), the controller outputs a signal to close the nitrogen regulating valve and shutoff valve. Continuous control: If the oxygen level suddenly rises to 7.5% (exceeding the upper limit), the regulating valve and shutoff valve are triggered to open, and the regulating valve opening is increased by 5% to 6.5%.

[0063] In another technical solution, a vent pipe is provided at the pyrolysis furnace outlet flue, which is connected to the atmosphere and equipped with a shut-off valve. A gas analyzer monitors the combustible gas concentration in the pyrolysis furnace outlet flue gas in real time. When the power plant boiler is shut down and the system coordination needs to be released, the controller performs the following time sequence operations: Immediately close all closing dampers and regulating dampers on the high-temperature flue, medium-temperature flue, and low-temperature flue to cut off the flue gas heat source; open the main valve of the nitrogen air duct and adjust the regulating valve to the fully open state, and inject nitrogen into the mixed flue for purging; at the same time, open the shut-off valve of the vent pipe and close the damper connecting the pyrolysis furnace outlet flue to the boiler furnace, so that the purge gas is discharged to the atmosphere through the vent pipe; Continue to run the booster fan and monitor the gas analyzer data. When the combustible gas concentration is detected to be zero for 15 consecutive minutes, stop the booster fan. Wait until the chain grate has transported all the solid residues in the furnace and then stop the chain grate. Finally, close the regulating valve and main valve of the nitrogen air duct, and when the temperature difference between each temperature measuring point of the pyrolysis furnace and the ambient temperature is less than 5°C and maintained for 15 minutes, close the shut-off valve of the vent pipe.

[0064] A vent line (with a shutoff valve) is installed at the pyrolysis furnace outlet flue, connecting it to the atmosphere as an emergency vent. A gas analyzer monitors the concentration of combustible gases (such as H₂, CO, and CH₄) in real time, and the controller is interlocked with the boiler shutdown signal. When the boiler shuts down, the heat-carrying flue gas is cut off, requiring the urgent venting of any remaining combustible gases within the pyrolysis furnace. The vent line works in conjunction with a nitrogen purge system, creating a dual inerting and venting safety mechanism.

[0065] The sequenced shutdown operation used includes the following steps: Step 1 (0-10 seconds): The boiler shutdown signal is triggered, and all dampers of the high / medium / low temperature flues are immediately closed to cut off the heat source.

[0066] Step 2 (10-30 seconds): Open the nitrogen main valve and fully open the regulating valve to purge the pyrolysis furnace and outlet flue. At the same time, open the vent pipe shut-off valve and close the baffle from the pyrolysis furnace to the boiler.

[0067] Step 3 (30 seconds to 15 minutes): Keep the booster fan running and the gas analyzer continuously monitoring. When the combustible gas concentration remains at 0% for 15 consecutive minutes (for example, H2 < 0.1%, CO < 0.05%), stop the fan.

[0068] Step 4: After the chain grate is cleaned, stop it and close the nitrogen valve. Wait until the temperature difference between the furnace and the ambient temperature is less than 5°C (e.g., from 60°C to 35°C) for 15 minutes, then close the vent valve.

[0069] Example parameter values: The combustible gas concentration threshold is set to 0% (absolute inerting required), and the temperature difference threshold is set to 5°C (to prevent residual heat ignition). This solves the industry challenge of pyrolysis gas accumulation and explosion during sudden shutdowns. Through strict sequence control, safe equipment shutdown is ensured with zero human intervention.

[0070] In another technical solution, a thermocouple group and a flue gas distribution valve system are configured within the pyrolysis furnace. At least three groups of thermocouples are arranged parallel to the width of the furnace in the center and at the edges of the pyrolysis furnace. A controller simultaneously receives a fiber desorption status image signal from a visual monitoring device and a temperature signal from the thermocouple group and performs the following operations: An image recognition algorithm is used to extract visual characteristic parameters of the fiber surface, including color depth and texture edge displacement. If the color depth is higher than a set threshold, the target temperature setting inside the pyrolysis furnace is increased by 5-10°C. If the texture edge displacement per unit time is lower than a preset value, the chain grate speed is reduced by 10%-25% to extend the material residence time. Real-time comparison of the synchronous temperature data of each group of thermocouples along the width of the pyrolysis furnace. If the temperature detected by any thermocouple inside the pyrolysis furnace exceeds the preset temperature upper limit, the opening of the high-temperature flue gas branch valve in the corresponding area will be immediately reduced by 20%~30%, and the opening of the low-temperature flue gas branch valve will be simultaneously increased by 15%~25%; if the temperature does not drop below the preset upper limit by at least 20°C within 60 seconds, the high-temperature flue gas branch valve will be closed; if the temperature detected by any thermocouple inside the pyrolysis furnace exceeds the preset temperature lower limit, the opening of the low-temperature flue gas branch valve in the corresponding area will be immediately reduced by 20%~30%, and the opening of the high-temperature flue gas branch valve will be simultaneously increased by 15%~25%; if the temperature does not drop above the preset lower limit by at least 20°C within 60 seconds, the low-temperature flue gas branch valve will be closed; If the temperatures of all thermocouples do not exceed the upper and lower temperature limits, but the temperature difference between any two groups continues to be greater than 30℃ for 3 minutes, then open the high-temperature flue gas branch valve in the low-temperature area by 10%~15% and close the low-temperature flue gas branch valve by 5%~10%; close the high-temperature flue gas branch valve in the high-temperature area by 5%~10% and open the low-temperature flue gas branch valve by 8%~12%; recheck the temperature difference every 30 seconds until the temperature difference ΔT≤20℃ and stop adjusting.

[0071] The pyrolysis furnace is equipped with independent thermocouple sets (such as K-type thermocouples) and a flue gas distribution valve system (including high, medium, and low temperature branch valves). At least three sets of thermocouples are placed along the width of the pyrolysis furnace (one set in the center and one set on each side edge) to monitor the temperature distribution. Visual monitoring devices (such as high-temperature industrial cameras) capture the fiber surface condition.

[0072] The visual device extracts the following through an image recognition algorithm: color depth value (0-1, 0 = pure white, 1 = completely black), which reflects the degree of carbon residue, with the threshold set at 0.8 (off-white fibers are qualified, dark gray exceeds the standard); texture edge displacement (pixels / second), which reflects the resin desorption rate, with the threshold set at 5 pixels / second (slow displacement indicates inadequate reaction).

[0073] When the color depth value of a batch of fibers is detected to be 0.85 (>0.8), the controller increases the oxygen content by 1%.

[0074] The flue gas distribution valve system includes independently controlled high temperature (700-1000℃), medium temperature (400-700℃), and low temperature (300-400℃) branch valves. The controller performs two-level regulation: Local over-temperature treatment (>600-650℃): Prioritize closing the high-temperature branch valve by 25% (e.g., 70% to 45%), and opening the low-temperature branch valve by 20% (e.g., 30% to 50%). If the temperature does not drop to the preset upper limit of -20℃ within 60 seconds (e.g., 600℃ needs to be reduced to ≤580℃), close the high-temperature branch valve.

[0075] Temperature field imbalance treatment (ΔT>30℃ for 3 minutes): For low temperature area: open the high temperature valve by 10%, and close the low temperature valve by 8% (for example: adjust the high temperature valve opening from 40% to 50%, and adjust the low temperature valve opening from 60% to 52%); for high temperature area: close the high temperature valve by 8%, and open the low temperature valve by 10% (for example: adjust the high temperature valve from 80% to 72%, and adjust the low temperature valve from 20% to 30%).

[0076] The optimal control termination meets two conditions: the temperature of all zones is stable within the preset upper limit of -20°C safety margin (for example, a 600°C system needs to be ≤580°C); the temperature difference between any two points in the furnace width direction is ≤20°C (fiber quality consistency requirement).

[0077] Specific implementation process example: Initial state: center-left-right temperatures = 580°C / 540°C / 620°C (ΔT left-center = 40°C, right overtemperature); First deal with the overtemperature on the right side: close the high-temperature valve 25%, open the low-temperature valve 20%, and adjust it to 585℃ after 5 minutes; Then process the low temperature on the left side: open the left high temperature valve 10%, close the left low temperature valve 8%, and after adjustment, the left side rises to 560℃; Adjusted temperature: center 580℃ / left 560℃ / right 585℃, maximum ΔT after adjustment = 25℃>20℃; Continue fine-tuning: close the high-temperature valve on the right side by 5%, and the temperature drops to 575°C after adjustment. Open the high-temperature valve on the left side by 5%, and the temperature rises to 565°C. Final temperature: center 580℃ / left side 565℃ / right side 575℃ (ΔT≤15℃), stop adjusting.

[0078] Through a dual closed-loop system combining visual fiber quality feedback with real-time temperature field control, the carbon residue rate is reduced to a negligible level. The principle of prioritizing cooling of low-temperature flue gas reduces nitrogen consumption by over 90%, ensuring the primary function of oxygen control. This resolves the issue of uneven temperature caused by heat loss at the edges of wide furnaces, improving the consistency of fiber recovery quality to industrial standards. The fiber's color and strength meet direct recycling standards, eliminating the need for secondary processing. Overtemperature emergency response time is shortened to minutes, eliminating the risk of fiber degradation due to overheating. Temperature field equilibrium and fiber desorption status are linked to achieve adaptive optimization of process parameters.

[0079] In another technical solution, the controller receives in real time the flue gas inlet temperature T1 detected by the mixed flue temperature measuring point, the average temperature T2 in the pyrolysis furnace detected by the thermocouple in the pyrolysis furnace, and the oxygen concentration O measured by the second oxygen measuring point set at the flue gas inlet of the pyrolysis furnace; the controller calculates the real-time flue gas temperature T=0.6T1+0.4T2, and calculates the pyrolysis intensity factor K based on the real-time flue gas temperature T and the oxygen concentration O. The calculation formula is: , where Tref is the median value of the predetermined optimal pyrolysis temperature, O ref is the median of the expected oxygen content, α and β are the temperature-dominant weight coefficients; Perform the following synchronous adjustment operations according to the pyrolysis intensity factor value: When the pyrolysis intensity factor is lower than the preset lower limit threshold, the opening of the medium-temperature flue damper is increased to increase the flue gas temperature, and the opening of the nitrogen duct regulating valve is reduced to increase the oxygen concentration; When the pyrolysis intensity factor is higher than the preset upper limit threshold, the opening of the medium-temperature flue damper is reduced to lower the flue gas temperature, and the opening of the nitrogen duct regulating valve is increased to reduce the oxygen concentration; If the flue gas temperature at the pyrolysis furnace outlet continues to deviate from the expected temperature range after adjustment, the opening of the regulating damper of the high-temperature flue or the low-temperature flue is adjusted at the same time.

[0080] The controller receives the power plant boiler load signal and the temperature change rate data detected by the thermocouple in the pyrolysis furnace in real time. When the boiler load change rate exceeds 5% / min for two consecutive minutes, it is judged as a sudden load drop or load increase and performs the following operations: When the load drops suddenly, reduce the chain grate speed to 70% of the original speed to extend the residence time of the material in the pyrolysis furnace; when the load rises suddenly, increase the chain grate speed to 130% of the original speed to shorten the residence time of the material in the pyrolysis furnace; freeze the pyrolysis intensity factor calculation for 5 minutes, and maintain the current flue gas adjustment damper and nitrogen valve opening unchanged; wait until the main thermocouple temperature change rate returns to within ±5℃ / min, reactivate the pyrolysis intensity factor calculation and release the speed freeze The controller collects real-time data on the mixed flue inlet temperature T1 (reflecting heat input), the average temperature within the pyrolysis furnace T2 (reflecting the actual reaction state), and the flue gas inlet oxygen concentration O (a safety indicator). These parameters are combined through weighted calculation into a single indicator, the pyrolysis intensity factor K, which is essentially a dimensionless value representing the overall intensity of the current pyrolysis reaction. The temperature component (T) takes the weighted average of T1 and T2 (e.g., T = 0.6T1 + 0.4T2), reflecting the balance between heat supply and furnace response. The oxygen component (O) directly uses data from the second oxygen measurement point to control the safety margin.

[0081] The control mechanism based on the pyrolysis intensity factor breaks through the limitations of traditional single-parameter control and achieves the ternary coordinated optimization of temperature, oxygen content, and reaction products. This significantly improves the adaptability of the pyrolysis process under variable operating conditions, avoiding runaway scenarios such as "fiber carbonization at acceptable temperatures" or "pyrolysis stagnation at safe oxygen content."

[0082] When the load change rate of the power plant boiler exceeds 3% / min for three consecutive minutes, the temperature weight coefficient α is dynamically modified based on the load change direction: When the load increases, the flue gas temperature weight coefficient α is increased to 1.2 times the original value; When the load decreases, the flue gas temperature weight coefficient α is reduced to 0.8 times the original value; Before the controller performs the synchronous adjustment operation according to the corrected pyrolysis intensity factor value, it verifies it through the temperature change rate of the thermocouple in the pyrolysis furnace. If the temperature change rate is inconsistent with the change direction of the pyrolysis intensity factor, the adjustment instruction is frozen and the manual intervention alarm is activated.

[0083] The controller dynamically adjusts the weighting coefficients β (oxygen weight) and α (temperature weight) in the K-factor calculation formula based on sudden changes in boiler load (rate of change > 3% / min). When the load increases, the temperature weighting is strengthened (α × 1.2) to quickly match heat demand; when the load decreases, the temperature weighting is weakened (α × 0.8) to prevent overheating.

[0084] During a sudden load increase, for example, from 70% to 75% within three minutes (rate of change >3% / min), α is increased from 0.5 to 0.6. If the thermocouple temperature changes by +8°C / min (in the same direction as the K factor), damper adjustment is executed; if the temperature remains unchanged, the adjustment is frozen. This addresses the secondary risks associated with mechanical K factor execution under extreme operating conditions and establishes a dual "correction-verification" safety mechanism within the control logic. This ensures that the pyrolysis system maintains safe and efficient operation even during periods of significant boiler fluctuations.

[0085] The controller receives the power plant boiler load signal and the temperature change rate data detected by the thermocouple in the pyrolysis furnace in real time. When the boiler load change rate exceeds 5% / min for two consecutive minutes, it is judged as a sudden load drop or load increase and performs the following operations: When the load drops suddenly, reduce the chain grate speed to 70% of the original speed to extend the residence time of the material inside the pyrolysis furnace; when the load rises suddenly, increase the chain grate speed to 130% of the original speed to shorten the residence time of the material inside the pyrolysis furnace; synchronously freeze the pyrolysis intensity factor calculation for 5 minutes, maintain the current flue gas adjustment damper and nitrogen valve opening unchanged; wait until the temperature change rate of the main thermocouple returns to within ±5℃ / min, reactivate the pyrolysis intensity factor calculation and release the speed freeze.

[0086] The controller monitors the boiler load change rate (e.g., percentage increase / decrease per minute) in real time and identifies a sudden increase / decrease when it exceeds 5% / min for two consecutive minutes. It also receives data on the pyrolysis furnace's temperature change rate (e.g., °C / min). Sudden load changes can lead to dramatic fluctuations in flue gas flow and temperature, prioritizing stabilization of the material reaction state. Therefore, the pyrolysis intensity factor calculation is frozen, and chain grate speed adjustment is used to compensate for temperature inertia.

[0087] As a specific implementation example, when the load drops suddenly from 100% to 90% of the set value, the chain speed is reduced to 70% (e.g., from 1 m / min to 0.7 m / min), extending the material residence time inside the pyrolysis furnace to 1.4 times its original value. The K-factor calculation is frozen for 5 minutes, and the current flue / nitrogen valve opening is maintained. When the load suddenly increases from a stable value of 60% to 68%, the chain speed is increased to 130% (e.g., from 1 m / min to 1.3 m / min), shortening the material residence time. The K-factor calculation is frozen, and the damper opening remains unchanged. The recovery condition is that the main thermocouple temperature change rate remains stable within ±5°C / min (e.g., -3°C / min), and K-factor control is restarted. This prevents the material from being "half-cooked" (during a sudden drop) or "overburned" (during a sudden increase) during deep peak-shaving boiler operation. By linking the speed and temperature change rate, a smooth temperature transition without overshoot is achieved.

[0088] The number of devices and processing scales described herein are intended to simplify the description of the present invention. Applications, modifications, and variations of the present invention will be readily apparent to those skilled in the art.

[0089] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A pyrolysis recovery system for waste wind turbine blades that is coordinated with power station boilers, characterized by: include: A power station boiler is provided with a furnace, a horizontal flue, a turning chamber and a tail flue in the direction of flue gas flow. A pyrolysis furnace is provided with an inlet for waste wind turbine blades, an outlet for fibers, an inlet for flue gas, and an outlet for flue gas; The mixed flue has an outlet connected to the flue gas inlet of the pyrolysis furnace through a booster fan. The inlet of the mixed flue is connected to the high-temperature flue, the medium-temperature flue and the low-temperature flue. The inlet of the high-temperature flue is connected to the horizontal flue, the inlet of the medium-temperature flue is connected to the turning chamber, and the inlet of the low-temperature flue is connected to the tail flue; wherein, The high-temperature flue, medium-temperature flue and low-temperature flue are respectively equipped with closing dampers and regulating dampers, and the mixed flue is equipped with oxygen measurement points and temperature measurement points; A nitrogen air duct, the outlet of which is connected to the inlet of the mixing flue, and a regulating valve is provided in the nitrogen air duct; The flue gas outlet of the pyrolysis furnace is connected to the furnace of the power plant boiler through the pyrolysis furnace outlet flue. The pyrolysis furnace outlet flue is equipped with a gas analyzer. The pyrolysis furnace is equipped with a thermocouple and a chain grate for transporting waste wind turbine blades and fibers. The pyrolysis furnace is equipped with a visual monitoring device for observing the fiber removal situation. Flue gas purification equipment, whose flue gas inlet is connected to the rear of the tail flue of the power station boiler, including denitrification device, dust removal device and desulfurization device; The controller is respectively connected to the oxygen measurement point and temperature measurement point of the mixed flue, the regulating valve of the nitrogen air duct, the thermocouple of the pyrolysis furnace, the visual monitoring device, the drive motor of the chain grate, the gas analyzer and the power station boiler load monitoring device for communication signals, and controls the actuators of the high-temperature flue, the medium-temperature flue and the low-temperature flue regulating dampers through signals; the controller is configured to perform oxygen control, temperature regulation, fiber quality protection and safety control operations during the pyrolysis process.

2. The pyrolysis recovery system for waste wind turbine blades in a power station boiler-cooperative manner according to claim 1 is characterized in that: The oxygen measurement point of the mixed flue is the first oxygen measurement point, and a second oxygen measurement point is also provided on the flue gas inlet of the pyrolysis furnace. The controller obtains the initial oxygen signal of the flue gas at the first oxygen measurement point and the target oxygen signal of the flue gas at the second oxygen measurement point; Based on the initial oxygen content signal of the flue gas and the preset target oxygen content range required for the pyrolysis reaction, combined with the real-time load status signal of the power plant boiler, the required nitrogen blending amount is calculated through a feedforward-feedback control algorithm; The controller generates and outputs a control signal to the regulating valve, dynamically adjusting its opening to add the calculated required nitrogen blending amount into the mixing flue. When the oxygen value monitored by the second oxygen measurement point exceeds the upper limit of the preset oxygen range required for the pyrolysis reaction, the controller controls the regulating valve to open wider to increase the nitrogen blending amount. When the oxygen value monitored by the second oxygen measurement point is lower than the lower limit of the preset range, the controller controls the opening of the regulating valve to decrease to reduce the nitrogen mixing amount.

3. The pyrolysis recovery system for waste wind turbine blades in a power station boiler-cooperative manner according to claim 1 is characterized in that: The flue gas at the pyrolysis furnace outlet is equipped with a vent pipe, which is connected to the atmosphere and installed with a shut-off valve. A gas analyzer monitors the combustible gas concentration in the flue gas at the pyrolysis furnace outlet in real time. When the power plant boiler is shut down and the system coordination needs to be released, the controller performs the following sequence operations: Immediately close all closing dampers and regulating dampers on the high-temperature flue, medium-temperature flue, and low-temperature flue to cut off the flue gas heat source; open the main valve of the nitrogen air duct and adjust the regulating valve to the fully open state, and inject nitrogen into the mixed flue for purging; at the same time, open the shut-off valve of the vent pipe and close the damper connecting the pyrolysis furnace outlet flue to the boiler furnace, so that the purge gas is discharged to the atmosphere through the vent pipe; Continue to run the booster fan and monitor the gas analyzer data. When the combustible gas concentration is detected to be zero for 15 consecutive minutes, stop the booster fan. Wait until the chain grate has transported all the solid residues in the furnace and then stop the chain grate. Finally, close the regulating valve and main valve of the nitrogen air duct, and when the temperature difference between each temperature measuring point of the pyrolysis furnace and the ambient temperature is less than 5°C and maintained for 15 minutes, close the shut-off valve of the vent pipe.

4. The pyrolysis recovery system for waste wind turbine blades in a power station boiler-cooperative manner according to claim 1 is characterized in that: The pyrolysis furnace is equipped with a thermocouple group and a flue gas distribution valve system. At least three groups of thermocouples are arranged parallel to the width of the furnace in the center area and the edge areas on both sides of the pyrolysis furnace. The controller simultaneously receives the fiber desorption state image signal from the visual monitoring device and the temperature signal of the thermocouple group and performs the following operations: An image recognition algorithm is used to extract visual characteristic parameters of the fiber surface, including color depth and texture edge displacement. If the color depth is higher than a set threshold, the target temperature setting inside the pyrolysis furnace is increased by 5-10°C. If the texture edge displacement per unit time is lower than a preset value, the chain grate speed is reduced by 10%-25% to extend the material residence time. Real-time comparison of the synchronous temperature data of each group of thermocouples along the width of the pyrolysis furnace. If the temperature detected by any thermocouple inside the pyrolysis furnace exceeds the preset temperature upper limit, the opening of the high-temperature flue gas branch valve in the corresponding area will be immediately reduced by 20%~30%, and the opening of the low-temperature flue gas branch valve will be simultaneously increased by 15%~25%; if the temperature does not drop below the preset upper limit by at least 20°C within 60 seconds, the high-temperature flue gas branch valve will be closed; if the temperature detected by any thermocouple inside the pyrolysis furnace exceeds the preset temperature lower limit, the opening of the low-temperature flue gas branch valve in the corresponding area will be immediately reduced by 20%~30%, and the opening of the high-temperature flue gas branch valve will be simultaneously increased by 15%~25%; if the temperature does not drop above the preset lower limit by at least 20°C within 60 seconds, the low-temperature flue gas branch valve will be closed; If the temperatures of all thermocouples do not exceed the upper and lower temperature limits, but the temperature difference between any two groups continues to be greater than 30℃ for 3 minutes, then open the high-temperature flue gas branch valve in the low-temperature area by 10%~15% and close the low-temperature flue gas branch valve by 5%~10%; close the high-temperature flue gas branch valve in the high-temperature area by 5%~10% and open the low-temperature flue gas branch valve by 8%~12%; recheck the temperature difference every 30 seconds until the temperature difference ΔT≤20℃ and stop adjusting.

5. The pyrolysis recovery system for waste wind turbine blades in cooperation with power station boilers according to claim 1 is characterized in that: The controller receives in real time the flue gas inlet temperature T1 detected by the mixed flue temperature measuring point, the average temperature T2 in the pyrolysis furnace detected by the thermocouple in the pyrolysis furnace, and the oxygen concentration O measured by the second oxygen measuring point set on the flue gas inlet of the pyrolysis furnace; the controller calculates the real-time flue gas temperature T=0.6T1+0.4T2, and calculates the pyrolysis intensity factor K based on the real-time flue gas temperature T and oxygen concentration O. The calculation formula is: , where T ref is the median value of the predetermined optimal pyrolysis temperature, O ref is the median of the expected oxygen content, α and β are the temperature-dominant weight coefficients; Perform the following synchronous adjustment operations according to the pyrolysis intensity factor value: When the pyrolysis intensity factor is lower than the preset lower limit threshold, the opening of the medium-temperature flue damper is increased to increase the flue gas temperature, and the opening of the nitrogen duct regulating valve is reduced to increase the oxygen concentration; When the pyrolysis intensity factor is higher than the preset upper limit threshold, the opening of the medium-temperature flue damper is reduced to lower the flue gas temperature, and the opening of the nitrogen duct regulating valve is increased to reduce the oxygen concentration; If the flue gas temperature at the pyrolysis furnace outlet continues to deviate from the expected temperature range after adjustment, the opening of the regulating damper of the high-temperature flue or the low-temperature flue is adjusted at the same time.

6. The pyrolysis recovery system for waste wind turbine blades in cooperation with power station boilers according to claim 5 is characterized in that: The controller receives the power plant boiler load signal in real time and performs the following operations: When the load change rate of the power plant boiler exceeds 3% / min for three consecutive minutes, the temperature weight coefficient α is dynamically modified based on the load change direction: When the load increases, the flue gas temperature weight coefficient α is increased to 1.2 times the original value; When the load decreases, the flue gas temperature weight coefficient α is reduced to 0.8 times the original value; Before the controller performs the synchronous adjustment operation according to the corrected pyrolysis intensity factor value, it verifies it through the temperature change rate of the thermocouple in the pyrolysis furnace. If the temperature change rate is inconsistent with the change direction of the pyrolysis intensity factor, the adjustment instruction is frozen and the manual intervention alarm is activated.

7. The pyrolysis recovery system for waste wind turbine blades coordinated with power station boilers according to claim 5 is characterized in that: The controller receives the power plant boiler load signal and the temperature change rate data detected by the thermocouple in the pyrolysis furnace in real time. When the boiler load change rate exceeds 5% / min for two consecutive minutes, it is judged as a sudden load drop or load increase and performs the following operations: When the load drops suddenly, reduce the chain grate speed to 70% of the original speed to extend the residence time of the material inside the pyrolysis furnace; When the load suddenly increases, the chain grate speed is increased to 130% of the original speed to shorten the residence time of the material inside the pyrolysis furnace; Synchronously freeze the pyrolysis intensity factor calculation for 5 minutes and maintain the current flue gas regulating damper and nitrogen valve opening unchanged; When the temperature change rate of the main thermocouple returns to within ±5°C / min, reactivate the pyrolysis intensity factor calculation and release the speed freeze.

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