Harmless resourceful treatment method for retired fan blade

Abstract

The invention discloses a harmless resourceful treatment method for retired fan blades. According to the method, a retired fan blade raw material and a strong base are mixed for a pyrolytic reaction, a silicon-containing solid is obtained, and the silicon-containing solid is used for preparing the mesoporous silicon oxide material. According to the method, the tar amount and toxic components generated in the treatment process of the retired fan blade can be remarkably reduced, environmental pollution is effectively avoided, the environmental protection treatment cost is reduced, meanwhile, the treatment process is greatly simplified, the energy consumption is reduced, and the high-performance mesoporous silicon oxide material is prepared.

Description

Technical Field

[0001] The invention relates to a harmless resource treatment method for retired wind turbine blades, belonging to the technical field of solid waste resource utilization. Background Art

[0002] With the rapid development of the wind power industry, the disposal of retired wind turbine blades has become an environmental problem that needs to be solved urgently. Retired wind turbine blades are mainly composed of glass fibers and thermosetting resins, and their structure is dense and difficult to degrade. A Chinese patent with patent publication number CN118495551A discloses a method for synthesizing MCM-41 molecular sieves using retired wind turbine blades, which includes the following steps: (1) pyrolyzing the retired wind turbine blades in an inert atmosphere, and then calcining them in an oxygen-containing atmosphere to obtain glass fibers; (2) mixing the glass fibers obtained in step (1) with an alkali and calcining them, and then performing solid-liquid separation to obtain a precursor solution containing silicon and aluminum elements; (3) mixing a template with water to obtain a template aqueous solution, and then mixing the template aqueous solution with the precursor solution obtained in step (2), and then adjusting the pH value of the obtained mixed solution to alkaline, and after standing and aging, performing a hydrothermal reaction at 50-140°C, and calcining the obtained solid phase product after solid-liquid separation. However, this method has the following defects:

[0003] (1) During the pyrolysis process, the resin decomposes to produce a large amount of tar (yield reaches 15-20wt%), which contains toxic substances such as phenols and polycyclic aromatic hydrocarbons. The subsequent treatment cost is high and the tar emission problem is not solved;

[0004] (2) The residual carbon attached to the surface of the glass fiber after pyrolysis requires an additional secondary calcination to remove it, which is a cumbersome process. In addition, the glass fiber needs to be mixed with alkali and calcined twice to extract the silicon source, which is a complex process with high energy consumption.

[0005] Therefore, there is an urgent need to develop a harmless resource treatment method for retired wind turbine blades to reduce tar emissions and at the same time prepare mesoporous silica materials with excellent performance to achieve the dual goals of "waste harm reduction and high-value utilization". Summary of the Invention

[0006] To address the problems of the prior art, the present invention aims to provide a harmless resource recovery method for retired wind turbine blades. This method significantly reduces tar emissions, avoids environmental pollution, and simultaneously produces a high-performance mesoporous silica material.

[0007] In order to achieve the above technical objectives, the present invention provides a method for harmless resource processing of retired wind turbine blades. The method is to mix the retired wind turbine blade raw materials with a strong base and perform a pyrolysis reaction to obtain a silicon-containing solid, which is used to prepare a mesoporous silica material.

[0008] On the one hand, the present invention uses a strong base as an alkaline catalyst to attack the ether bonds and benzene ring side chains in the resin molecules in the retired fan blades, promote decarboxylation chain scission reactions, and decompose the macromolecular resin into small molecular gases such as CO2 and H2O, avoiding the large-scale production of tar, and reducing the tar yield by more than 70% compared with conventional pyrolysis reactions; on the other hand, the base is used to react with SiO2 in the glass fiber in the retired fan blades to generate sodium silicate, which promotes the conversion and extraction of the silicon source and eliminates the secondary calcination step of the glass fiber and the base in the conventional process.

[0009] As a preferred solution, the mass ratio of the decommissioned wind turbine blade raw material to the strong alkali is 1:0.5-0.8. Controlling the strong alkali dosage within an appropriate range helps improve resource recovery efficiency. Excessively low alkali dosage can lead to incomplete resin decomposition and incomplete glass fiber reaction in the decommissioned wind turbine blades, resulting in a relatively high pyrolysis tar yield and a relatively low silicon extraction rate. Excessive alkali dosage, on the other hand, can waste raw materials and increase costs.

[0010] As a preferred embodiment, the pyrolysis reaction conditions are: a protective atmosphere, a temperature of 550-650°C, and a time of 40-80 minutes, more preferably 50-80 minutes. Controlling the pyrolysis temperature and time within appropriate ranges facilitates the efficient co-pyrolysis of the strong alkali with the retired wind turbine blades.

[0011] As a preferred solution, the protective atmosphere includes nitrogen and / or an inert gas, and the gas flow rate is controlled to be 1-2 L / min.

[0012] As a preferred solution, the strong base includes at least one of sodium hydroxide and potassium hydroxide.

[0013] As a preferred solution, the particle size of the retired fan blade raw material is 5-20 mm. Controlling the particle size of the retired fan blade raw material within an appropriate range can increase the specific surface area of ​​the material, allowing the strong base to evenly contact the resin and glass fiber in the retired fan blade raw material.

[0014] As a preferred scheme, the preparation process of the mesoporous silica material is: the silicon-containing solid is soaked in water to obtain a sodium silicate solution, the sodium silicate solution is then mixed with a template solution and allowed to stand for aging, the obtained aged mixed solution is subjected to a hydrothermal reaction and then solid-liquid separation, and the obtained solid phase product is calcined to obtain a mesoporous silica material.

[0015] As a preferred solution, the water immersion process comprises a solid-liquid mass ratio of 1:8-12, a temperature of 60-80°C, and a duration of 2-4 hours. The present invention achieves a silicon extraction rate of ≥20% after water immersion, achieving efficient conversion of glass fibers from retired wind turbine blades.

[0016] As a preferred solution, the molar ratio of silicon element to template and water in the mixture of the sodium silicate solution and the template solution is 1:(0.1-0.3):(250-400).

[0017] As a preferred solution, the mass concentration of the template solvent is 3-5%.

[0018] As a preferred embodiment, the template includes at least one of dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, hexadecylpyridinium bromide, and hexadecyltrimethylammonium chloride. The template self-assembles under alkaline conditions to form micelles, providing a guiding template for the mesoporous structure.

[0019] As a preferred solution, the sodium silicate solution is mixed with the template solution to adjust the pH value of the system to 10-12, and then allowed to stand for aging. The aging time is preferably 12-24 hours.

[0020] As a preferred solution, the conditions of the hydrothermal reaction are: temperature of 120-140°C, time of 12-36h;

[0021] As a preferred solution, the calcination conditions are: temperature of 600-650°C and time of 4-6 hours. Controlling the calcination temperature and time within the appropriate range is beneficial to improving the comprehensive properties of the material.

[0022] As a preferred embodiment, the mesoporous silica material is MCM-41 mesoporous silica, which has a specific surface area of ​​200-500 m² / g, an average pore diameter of 2-8 nm, and a pore volume of 1.5-2.0 cm³ / g.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention significantly reduces tar emissions (emissions are reduced by more than 85%) and the production of toxic components (such as polycyclic aromatic hydrocarbons (PAHs) by more than 90%) by co-pyrolyzing retired fan blades with alkali, effectively avoiding environmental pollution and reducing environmental treatment costs. At the same time, the steps of residual carbon oxidation and secondary calcination of glass fiber are omitted, simplifying the treatment process and greatly reducing energy consumption.

[0025] (2) The present invention has a high extraction rate of silicon elements from retired fan blades, and realizes the efficient conversion of glass fibers in retired fan blades. The prepared mesoporous silica material has a large specific surface area and rich pores, and has excellent performance in the fields of adsorption and catalysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0027] Figure 1 This is the XRD characteristic diagram of the mesoporous silicon oxide material prepared in Example 1 of the present invention.

[0028] Figure 2 This is the SEM morphology of the mesoporous silicon oxide material prepared in Example 1 of the present invention.

[0029] Figure 3 This is a comparison chart of the pyrolysis product components of Example 1 of the present invention and Comparative Example 1.

[0030] Figure 4 This is a comparison chart of the pyrolysis gas components of Example 1 of the present invention and Comparative Example 1.

[0031] Figure 5 These are the Py-GCMS test graphs of Example 1 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] Example 1

[0034] (1) Preprocessing

[0035] 100.0g of retired fan blades were initially crushed to 50-100mm using a jaw crusher. The particles were then further crushed in a planetary ball mill (ball-to-material ratio 5:1, rotation speed 300 r / min, crushing time 30 minutes). After passing through a standard sieve, particles with a size of 10-15mm were selected (particle size distribution, as measured by laser particle size measurement, D50 = 12.5mm). The crushed blade particles were then mixed with 60.0g of sodium hydroxide (mass ratio 1:0.6) in a twin-screw mixer and mixed at 80°C for 30 minutes (screw speed 200 r / min) to obtain a uniformly mixed granular material.

[0036] (2) Co-pyrolysis

[0037] The mixed material from step (1) was transferred to a quartz tubular reactor (inner diameter 50 mm, length 800 mm). The two ends of the reactor were connected to a gas sampling system and an exhaust gas condensation collection system. High-purity nitrogen (99.999%) was first introduced to replace the air in the reactor. The flow rate was controlled at 1.5 L / min (regulated by a mass flow controller D07-19B) and the replacement time was 30 min. After the replacement was completed, the programmed temperature controller was turned on and the temperature was raised to 600°C at a rate of 8°C / min (the center temperature of the reactor was monitored in real time during the heating process, with a deviation of ≤±2°C). After reaching the target temperature, the temperature was maintained for 60 min for co-pyrolysis reaction.

[0038] The pyrolysis tail gas was condensed in two stages (the first stage condensation temperature was 150°C, and the light oil was collected; the second stage condensation temperature was 0°C, and the heavy oil was collected). The two-stage condensation products were combined to obtain tar, which was weighed on an electronic balance (accuracy 0.001g) and the tar yield was 1.5g. At the same time, a gas chromatograph was used to detect the pyrolysis gas components online (the chromatographic column was an HP-5 capillary column, the detectors were TCD and FID, and the column temperature program was: 50°C for 2min, then increased to 200°C at 10°C / min and held for 5min). The results showed that H2 accounted for 82.5% of the pyrolysis gas, CH4 accounted for 15.2%, and CO accounted for 2.3%. No CO2 or phenolic gases were detected.

[0039] After the reaction was completed, the heating device was turned off, and nitrogen was continued to be passed to cool to room temperature (cooling rate ≤ 5°C / min), and the solid product remaining in the reactor was taken out.

[0040] (3) Water extraction of silicon

[0041] The solid product (approximately 120 g) from step (2) was transferred to a 5 L three-necked flask and placed in a constant temperature water bath at a solid-liquid ratio of 1:10 (i.e., 120 g of solid was added to 1200 mL of deionized water). The temperature was controlled at 70°C (temperature difference ± 1°C) and an electric stirrer (model JJ-1, power 60 W) was used to stir and leached at a rate of 400 r / min for 3 h. During the leaching process, 5 mL of the sample was sampled every 30 min and filtered through a 0.22 μm filter membrane. The Si element concentration in the filtrate was determined using an inductively coupled plasma optical emission spectrometer (ICP-OES). Leaching was stopped when the concentration stabilized (fluctuation ≤ 2%).

[0042] After leaching, vacuum filtration (vacuum degree -0.08 MPa) was performed using a Büchner funnel (diameter 100 mm) to obtain a clear solution containing sodium silicate (tested Si concentration was 18.2 g / L). The silicon extraction yield was calculated to be 23.5% (extraction yield = (mass of Si in solution / initial Si mass in leaves) × 100%). The filter residue was dried and weighed, and its mass was approximately 5 g (mainly a small amount of unreacted inorganic impurities).

[0043] (4) Template compounding and aging

[0044] Weigh 8.5 g of dodecyltrimethylammonium bromide (template), add 255 mL of deionized water (mass ratio 1:30), and stir to dissolve in a 50°C water bath (stirring rate 300 r / min) to obtain a template aqueous solution (concentration 3.3 wt%).

[0045] Take 500 mL of the clarified solution containing sodium silicate in step (3) (the molar amount of Si element is 0.15 mol as determined by ICP-OES). According to the molar ratio of Si: template: water = 1:0.2:300, 0.03 mol of template (corresponding to 180 mL of template aqueous solution) and 4.5 L of deionized water (supplemented until the total water volume meets the molar ratio) need to be added. The above solution and template aqueous solution are added to a 10 L beaker. 1 mol / L dilute hydrochloric acid is slowly added dropwise under magnetic stirring (speed 500 r / min) to adjust the pH of the mixture to 11.0 (real-time monitoring with a pH meter PHS-3C, accuracy ±0.01). After the addition is completed, continue stirring for 10 minutes, then transfer to a sealed glass container and place it in a constant temperature chamber at 25°C for 18 hours (observe every 6 hours during the aging process, and the solution gradually forms a milky white gel).

[0046] (5) Hydrothermal synthesis and calcination

[0047] The aged gel-like mixture was transferred to a 5L polytetrafluoroethylene-lined hydrothermal reactor (70% fill), sealed, and placed in a forced air drying oven (model DHG-9240A) for a hydrothermal reaction at 130°C for 24 hours (temperature fluctuation ±1°C). After the reaction, the mixture was naturally cooled to room temperature and centrifuged (8000 rpm, 15 minutes) to obtain a solid product. The solid product was then washed three times with deionized water (five times the mass of the solid phase each time) until the pH of the washing solution reached 7.0.

[0048] The washed solid product was placed in a vacuum drying oven and dried at 105°C and -0.09 MPa for 12 hours to obtain a xerogel powder. The xerogel was then transferred to a 500 mL corundum crucible and placed in a box-type resistance furnace. The temperature was increased at a rate of 2.5°C / min to 620°C (temperature ramp-up process: room temperature → 200°C for 1 hour → 400°C for 1 hour → 620°C). The product was calcined in air for 5 hours (maintaining an oxygen content of ≥20% in the furnace during calcination) and naturally cooled to room temperature to obtain a white mesoporous silica powder.

[0049] The properties of the mesoporous silica material were determined using a specific surface area and pore size analyzer. Using nitrogen as the adsorbent, an adsorption-desorption experiment was conducted at -196°C. The specific surface area calculated by the BET method was 386 m² / g, the average pore diameter calculated by the BJH method was 3.5 nm, and the pore volume was 1.72 cm³ / g. XRD analysis was performed using an X-ray diffractometer. Figure 1 As shown in FIG, a characteristic diffraction peak appears at 2θ = 2.3°, confirming the hexagonal mesoporous structure of MCM-41 type mesoporous silica. Figure 2 This is an electron microscope image of the mesoporous silicon oxide material prepared in Example 1. Observation using a scanning electron microscope (SEM) (model SU8020) shows that the material has a fibrous agglomerated structure with a smooth surface and no obvious impurities.

[0050] Example 2

[0051] The amount of NaOH was adjusted to 50.0 g (mass ratio 1:0.5), and the remaining steps were the same as in Example 1. Under these conditions, the pyrolysis tar yield was 2.8 g, the silicon extraction rate was 22.1%, the specific surface area of ​​mesoporous silica was 362 m² / g, and the average pore diameter was 3.7 nm.

[0052] Example 3

[0053] The amount of NaOH was increased to 70.0 g (mass ratio 1:0.7), and the remaining steps were the same as in Example 1. Under these conditions, the pyrolysis tar yield was 1.2 g, the silicon extraction rate was 24.2%, the specific surface area of ​​mesoporous silica was 392 m² / g, and the average pore diameter was 3.4 nm.

[0054] Example 4

[0055] The amount of NaOH was adjusted to 30.0 g (mass ratio 1:0.3), and the remaining steps were the same as in Example 1. Under these conditions, the pyrolysis tar yield was 8.6 g, the silicon extraction rate was 18.7%, the specific surface area of ​​the mesoporous silica was 312 m² / g, and the average pore diameter was 4.0 nm.

[0056] Example 5

[0057] The amount of NaOH was increased to 90.0 g (mass ratio 1:0.9), and the remaining steps were the same as in Example 1. Under these conditions, the pyrolysis tar yield was 1.8 g, the silicon extraction rate was 22.8%, the specific surface area of ​​the mesoporous silica was 335 m² / g, and the average pore diameter was 3.8 nm.

[0058] Comparative Example 1

[0059] (1) Single pyrolysis: 100.0 g of retired fan blades (crushed to 10-15 mm) were taken and nitrogen (1.5 L / min) was introduced into the same quartz tube reactor as in Example 1. The temperature was raised to 600 °C at 8 °C / min and kept at that temperature for 60 min. 26.8 g of tar was collected (GC-MS analysis showed that it contained 42.5 wt% of phenols and 18.3 wt% of polycyclic aromatic hydrocarbons).

[0060] (2) Residual carbon removal: The solid product after pyrolysis (containing glass fiber and residual carbon) was placed in a muffle furnace, heated to 550°C at 5°C / min in an air atmosphere, and kept at this temperature for 30 minutes to calcine and remove the residual carbon (residual carbon removal rate 98.2%), thereby obtaining gray-white glass fiber.

[0061] (3) Secondary calcination to extract silicon: glass fiber and sodium hydroxide were mixed in a mass ratio of 1:1, calcined at 650 °C for 60 min (heating rate 5 °C / min), and then deionized water at 70 °C was added in a solid-liquid ratio of 1:10. The mixture was stirred and leached for 3 h. The sodium silicate solution was filtered to obtain a silicon extraction rate of 23.2%.

[0062] (4) The subsequent template compounding, hydrothermal synthesis and calcination steps were the same as those in Example 1, and finally a mesoporous silica material was obtained, which had a specific surface area of ​​275 m² / g, an average pore diameter of 4.5 nm, and a pore volume of 1.48 cm³ / g.

[0063] Compared with Comparative Example 1, the present invention greatly simplifies the process steps, omitting the residual carbon calcination and secondary calcination of glass fiber, shortening the process by 30%, directly reducing the processing time by nearly 5.33 hours and energy consumption by 28%, greatly improving production efficiency and saving energy costs. Figure 3 As shown in the comparative diagram of the pyrolysis product components of Example 1 of the present application and the comparative example, the tar yield was reduced from 26.8g to 1.5g, a 94.4% reduction in emissions, significantly reducing the tar production. Figure 4 This is a comparison chart of the pyrolysis gas components of Example 1 and Comparative Example 1 of the present application. Figure 5The Py-GCMS test graphs for Example 1 and Comparative Example 1 of this application show that the treatment method of the present invention can reduce the content of toxic components (phenols and polycyclic aromatic hydrocarbons) in pyrolysis gas by over 90%. The generated pyrolysis gas contains as much as 82.5% H2 (as in Example 1). H2 is a clean and efficient energy carrier with extremely high utilization value. However, Comparative Example 1 does not reflect the dominant components of pyrolysis gas, resulting in lower energy utilization efficiency. The mesoporous silica prepared in Comparative Example 1 has a specific surface area of ​​275 m² / g, while the product of the present invention has a higher specific surface area (312-392 m² / g). A higher specific surface area means the material has superior adsorption properties and surface activity, and has greater application value in fields such as catalysis and adsorption.

[0064] Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not limited to the embodiments shown herein, but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A method for harmless resource recovery of retired wind turbine blades, characterized by: The retired wind turbine blade raw material is mixed with a strong base to undergo a pyrolysis reaction to obtain a silicon-containing solid, which is used to prepare a mesoporous silicon oxide material.

2. The harmless resource treatment method for retired wind turbine blades according to claim 1 is characterized by: The mass ratio of the retired wind turbine blade raw material to the strong alkali is 1:0.5~0.

8.

3. A harmless resource treatment method for retired wind turbine blades according to claim 1 or 2, characterized in that: The conditions of the pyrolysis reaction are: a protective atmosphere, a temperature of 550-650° C., and a time of 40-80 min.

4. A harmless resource treatment method for retired wind turbine blades according to claim 1 or 2, characterized in that: The strong base includes at least one of sodium hydroxide and potassium hydroxide.

5. The harmless resource treatment method for retired wind turbine blades according to claim 1 is characterized by: The particle size of the retired fan blade raw material is 5~20mm.

6. The harmless resource treatment method for retired wind turbine blades according to claim 1 is characterized by: The preparation process of the mesoporous silica material is as follows: silicon-containing solid is soaked in water to obtain a sodium silicate solution, the sodium silicate solution is mixed with a template solution and then allowed to stand for aging, the obtained aged mixed solution is subjected to a hydrothermal reaction and then solid-liquid separation, and the obtained solid phase product is calcined to obtain the mesoporous silica material.

7. The harmless resource treatment method for retired wind turbine blades according to claim 6 is characterized by: The conditions of the water immersion process are: solid-liquid mass ratio of 1:8-12, temperature of 60-80° C., and time of 2-4 hours.

8. The harmless resource treatment method for retired wind turbine blades according to claim 6 is characterized by: The molar ratio of silicon element to template and water in the mixed solution of the sodium silicate solution and the template solution is 1:(0.1-0.3):(250-400).

9. The method for harmless resource recovery of retired wind turbine blades according to claim 6, characterized in that: The conditions of the hydrothermal reaction are: temperature of 120-140°C and time of 12-36 hours; The calcination conditions are: temperature of 600-650° C. and time of 4-6 hours.

10. The method for harmless resource recovery of retired wind turbine blades according to any one of claims 6 to 9, characterized in that: The mesoporous silica material has a specific surface area of ​​200-500 m² / g, an average pore diameter of 2-8 nm, and a pore volume of 1.5-2.0 cm³ / g.

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