Crushing and recycling method of fiber aerogel felt

Abstract

The invention discloses a crushing and recycling method of a fiber aerogel felt, which effectively avoids fiber fracture and aerogel pore collapse caused by one-time high-stress impact of traditional crushing equipment through a stepped crushing process of performing low-rotating-speed mechanical rolling coarse crushing and airflow impact fine crushing on a waste aerogel felt in sequence. The integrity of the fiber and aerogel structure is protected. The porosity of the crushed aerogel powder is greater than or equal to 92%, and the specific surface area loss rate is controlled to be 1t; 6%, fiber diameter retention rate gt; the porosity collapse rate of the aerogel is 1t; the heat conductivity coefficient of the regenerated material treated by the method is only increased by less than or equal to 2%, and the regenerated material still has good heat insulation performance.

Description

Technical Field

[0001] This invention relates to the field of aerogel felt recycling technology, specifically to a method for crushing and recycling fiber aerogel felt. Background Technology

[0002] Fiber aerogel felt, as a novel nanoporous thermal insulation material, has been widely used in aerospace, petrochemical, building insulation, and new energy fields. With the expansion of its application scale, the recycling and disposal of scrap materials (accounting for approximately 15-20% of total production) and waste products generated during production and construction has become increasingly prominent.

[0003] Currently, the industry mainly uses the following methods for recycling: First, ordinary shear crushers are used to mechanically crush the waste before further recycling. However, existing mechanical crushing methods suffer from excessive mechanical impact, leading to severe damage to the fiber structure, collapse of aerogel nanopores, excessively high thermal conductivity, and low tensile strength in the recycled material. Second, aerogel is recovered by decomposing organic components at high temperatures. However, when the processing temperature exceeds 500℃, the SiO2 framework sinters, the aerogel mesoporous structure collapses irreversibly, the specific surface area decreases significantly, the thermal insulation performance declines, and the high-temperature energy consumption is as high as 8-10 kW·h / kg, resulting in high costs. Third, solvents are used to dissolve the binder before separation and recovery. However, this method generates a large amount of organic wastewater, significantly increasing treatment costs. In addition, existing recycling technologies cannot achieve controllable particle size of the crushed material, limiting the application scenarios of the crushed and recycled material; and dry processing also causes serious dust pollution, polluting the environment and harming human health. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the existing technology, the purpose of the present invention is to provide a crushing and recycling method for fiber aerogel felt, which solves the problem that the existing mechanical crushing and recycling methods have excessive mechanical impact force, which causes serious damage to the fiber structure, collapse of aerogel nanopores, and further reduces the thermal insulation performance.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A method for pulverizing and recycling fiber aerogel felt includes the following steps:

[0007] S1. Collect waste aerogel felt, remove impurities and substandard products to obtain waste aerogel felt to be recycled.

[0008] S2. The waste aerogel felt to be recycled is mechanically crushed to obtain mechanically crushed material;

[0009] S3. Perform gas-solid separation on the mechanically pulverized material, and screen the separated solid material to obtain pre-screened fiber aerogel powder.

[0010] S4. The initially screened fiber aerogel powder is pulverized a second time using airflow impact to obtain airflow pulverized material;

[0011] S5. Perform gas-solid separation on the air-jet pulverized material and collect the pulverized and recovered aerogel powder.

[0012] Furthermore, in step S2, the mechanical crushing is performed using a mechanical crusher, with the crushing speed controlled at 1000-2000 rpm and the rolling pressure of the roller cutter at 10-30 N / mm. 2 The blade spacing of the roller pressing tool is 2-8mm.

[0013] Furthermore, when the waste aerogel felt meets any of the following conditions:

[0014] (a) The waste aerogel felt contains organic components;

[0015] (b) The thermal conductivity of the waste aerogel felt is <0.018 W / (m·K);

[0016] (c) The specific surface area of ​​the waste aerogel felt is >800 m² 2 / g;

[0017] Control the grinding speed to be between 1000 rpm and 1600 rpm, and the torque to be 10 N / mm. 2 Roller pressure ≤20N / mm 2 5mm < Roller cutting tool blade spacing ≤ 8mm;

[0018] When the waste aerogel felt does not meet all the conditions in (a), (b), and (c), control the crushing speed to be 1600 rpm < crushing speed ≤ 2000 rpm and 20 N / mm. 2 < Roller pressure ≤ 30 N / mm 2 2mm≤screw press blade spacing<5mm.

[0019] Furthermore, in step S2, during the mechanical crushing process, a liquid nitrogen spraying system is used to continuously spray the waste aerogel felt to be recovered, with a liquid nitrogen flow rate of 5-10 L / min.

[0020] Furthermore, in step S3, the specific operation of gas-solid separation is as follows: mechanically crushed materials are conveyed to a cyclone separator for gas-solid separation under negative pressure by a vacuum feeder; the vacuum fan frequency of the vacuum feeder is 25-35Hz, the vacuum feeding pressure difference is -1±-0.5KPa; the rotation speed of the cyclone separator is 1000-2000rpm, and the tilt angle is 30-60°.

[0021] Furthermore, in step S3, the screening is a vibrating screen with a frequency of 50-100Hz, an amplitude of 2-5mm, and a screen mesh size of 20-50 mesh.

[0022] Furthermore, in step S4, the specific operation of the airflow impact is as follows: a screw feeder is used to continuously convey the pre-screened fiber aerogel powder to the crushing zone, while a compressed airflow accelerated by a Laval nozzle is injected into the crushing zone to collide and crush the pre-screened fiber aerogel powder, thereby obtaining airflow-crushed material; the pressure of the compressed airflow is 0.35-0.7 MPa, and the operating frequency of the screw feeder is 20-50 Hz.

[0023] Furthermore, in step S5, the specific operation of the gas-solid separation is as follows: the negative pressure generated by the dust removal fan is used to transport the airflow to crush the material, so that it flows through the fluidized bed airflow channel and the classifier in sequence, and then flows into the cyclone separator for gas-solid separation. The separated solid material flows into the bottom of the cyclone separator to wait for unloading, and the separated gaseous material is filtered by the bag filter and discharged into the atmosphere.

[0024] The fluidized bed airflow channel is a multi-stage zigzag channel with a width of 10-20mm. The central axis of each channel section forms an angle of 30-60° with the negative pressure suction direction. The classifier operates at a frequency of 5-50Hz, the dust removal fan operates at a frequency of 20-50Hz, and the cyclone separator is tilted at an angle of 30-60°.

[0025] Furthermore, the grading wheel adopts a multi-stage blade structure with 60-100 blade teeth.

[0026] Furthermore, in step S5, the specific operation for collection is as follows: open the opening at the bottom of the cyclone separator for unloading, and control the outflow velocity of the powder through a mass flow controller to control the dust emission concentration to <20mg / m³. 3 After unloading, the pulverized and recycled fiber aerogel powder is obtained.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention provides a method for pulverizing and recycling fiber aerogel felt. This method employs a stepped pulverization process, involving low-speed mechanical roller crushing followed by airflow impact pulverization of the waste aerogel felt. This effectively avoids fiber breakage and aerogel pore collapse caused by the single high-stress impact of traditional pulverizing equipment, thus protecting the integrity of the fiber and aerogel structure. The pulverized aerogel powder has a porosity ≥92%, a specific surface area loss rate controlled <6%, a fiber diameter retention rate >97%, and an aerogel pore collapse rate <1%. This significantly improves the performance of the recycled material, and the thermal conductivity of the recycled material treated by this invention only increases by ≤2%, still exhibiting good thermal insulation properties.

[0029] 2. This invention controls the process conditions of vibrating screening, enabling the grading of materials with different particle sizes to obtain pulverized materials with particle sizes ranging from 5 to 2000 μm. This overcomes the shortcomings of existing technologies where the particle size of pulverized materials is uncontrollable. This flexible particle size adjustment function expands the application range of recycled materials, allowing them to be widely used in various industrial fields. Furthermore, by designing a vacuum feeding system and a highly efficient gas-solid separation system, and precisely controlling the process parameters of each system, combined with the control of the discharge flow rate, this invention can control the dust emission concentration to within 20 mg / m³. 3 The following measures significantly reduce dust pollution and meet environmental protection requirements.

[0030] 3. This invention employs a closed-loop recycling process, achieving efficient recycling of waste aerogel felt, avoiding energy consumption and environmental pollution, and meeting the requirements of green, low-carbon, and circular economic development. Simultaneously, through process optimization and equipment improvement, processing costs are significantly reduced, improving the economic benefits for enterprises. Attached Figure Description

[0031] Figure 1 This is a flowchart of the pulverization and recycling method for the fiber aerogel felt of the present invention. Detailed Implementation

[0032] The specific embodiments of the present invention will be described in further detail below with reference to specific examples.

[0033] The numerical ranges in this invention should be understood to also specifically disclose each intermediate value between the upper and lower limits of the range. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail. The terms “comprising,” “including,” “having,” “containing,” etc., as used herein are open-ended, meaning that they include but are not limited to.

[0035] Unless otherwise specified, the experimental methods used in this invention are all conventional methods.

[0036] Unless otherwise specified, all materials and reagents used in this invention can be purchased or synthesized by known methods.

[0037] In the quantitative experiments of this invention, each experiment was repeated three times, and the average value of the results was taken.

[0038] I. This invention provides a method for pulverizing and recycling fiber aerogel felt, comprising the following steps:

[0039] S1. Collect waste aerogel felt, remove impurities and substandard products to obtain waste aerogel felt to be recycled; (substandard products refer to any waste aerogel felt that does not meet the performance requirements of GB / T 34336-2017)

[0040] S2. The waste aerogel felt to be recycled is mechanically crushed to obtain mechanically crushed material;

[0041] S3. Perform gas-solid separation on the mechanically pulverized material, and screen the separated solid material to obtain pre-screened fiber aerogel powder.

[0042] S4. The initially screened fiber aerogel powder is pulverized a second time using airflow impact to obtain airflow pulverized material;

[0043] S5. Perform gas-solid separation on the air-jet pulverized material and collect the pulverized and recovered aerogel powder.

[0044] In specific implementation, step S2, the mechanical crushing specifically involves: using a low-energy-density mechanical crusher for crushing, with a crushing speed of 1000-2000 rpm and a roller pressure of 10-30 N / mm for the roller cutters. 2 The blade spacing of the roller pressing tool is 2-8mm.

[0045] This avoids excessive breakage of the aerogel felt due to mechanical impact and excessive rotation speed, thus protecting the integrity of the fiber and aerogel structures. In practice, the rotation speed is adjusted according to the hardness of the raw material; a lower speed is used for soft materials, and a higher speed is used for hard materials.

[0046] In specific implementation, waste aerogel felts shall meet any of the following conditions:

[0047] (a) The waste aerogel felt contains organic components;

[0048] (b) The thermal conductivity of the waste aerogel felt is <0.018 W / (m·K);

[0049] (c) The specific surface area of ​​the waste aerogel felt is >800m2 / g;

[0050] Control the grinding speed to be between 1000 rpm and 1600 rpm, and the torque to be 10 N / mm. 2 Roller pressure ≤20N / mm 2 5mm < Roller blade spacing ≤ 8mm; When the waste aerogel felt does not meet all the conditions in (a), (b), and (c), control 1600rpm < crushing speed ≤ 2000rpm and 20N / mm. 2 < Roller pressure ≤ 30 N / mm 2 2mm≤screw press blade spacing<5mm.

[0051] In practice, the surface of the roller pressing tool is coated with a nano-alumina ceramic composite coating.

[0052] This increases the tool hardness, reduces the coefficient of friction, and lowers the internal stress level of the tool. The final tool hardness reaches ≥2000 HV, the coefficient of friction ≤0.15, and the mechanical stress is reduced to <10 N / mm. 2 (1 / 5 of traditional equipment) Reduces frictional loss while avoiding cracks or gaps caused by high internal stress.

[0053] In practice, the screen mesh size inside the crushing chamber of the mechanical crusher is 8-20 mesh. This mesh size setting meets the particle size requirements of the target product and the characteristics of the coarse crusher.

[0054] In specific implementation, during step S2, the waste aerogel felt to be recycled is continuously sprayed with liquid nitrogen using a liquid nitrogen spraying system during the mechanical crushing process, and the liquid nitrogen flow rate of the liquid nitrogen spraying system is controlled to be 5-10 L / min.

[0055] In this way, the temperature of the waste aerogel felt can be effectively controlled to always be below 40°C. When the aerogel felt substrate is polyester organic fiber or pre-oxidized fiber, the problem of the material being difficult to crush and easily agglomerated to form high temperature can be effectively alleviated, thereby inhibiting the collapse of aerogel pores.

[0056] In practice, during the mechanical crushing process, the temperature of the waste aerogel felt is monitored in real time using a temperature sensor.

[0057] In this way, by controlling the temperature in real time (±2℃ accuracy), the material temperature can be accurately monitored to ensure that the material temperature is always below 40℃ during the crushing process, thus inhibiting the collapse of aerogel pores.

[0058] In specific implementation, in step S3, the gas-solid separation operation is as follows: the mechanically crushed material is conveyed to the cyclone separator for gas-solid separation under negative pressure by a vacuum feeder; the vacuum fan frequency of the vacuum feeder is 25-35Hz, the vacuum feeding pressure difference is -1±-0.5KPa; the rotation speed of the cyclone separator is 1000-2000rpm, and the tilt angle is 30-60°.

[0059] In this way, transporting mechanically crushed materials through a closed, negative-pressure pipeline eliminates dust pollution, protecting the environment and human health. Furthermore, this configuration of the cyclone separator's rotation speed and tilt angle ensures efficient gas-solid separation.

[0060] In specific implementation, in step S3, the separated solid material flows into the bottom of the cyclone separator to wait for unloading. During unloading, the air vibration and pulse device on the side wall of the cyclone separator and the vacuum unloading butterfly valve at the bottom outlet of the cyclone separator are opened to achieve the unloading of the separated solid material. During the unloading process, the pulse pressure is controlled at 0.2-0.5MPa to ensure smooth unloading and prevent material from adhering to and clogging the hopper.

[0061] In specific implementation, in step S3, the screening is carried out by using a circular vibrating screen with a frequency of 50-100Hz, an amplitude of 2-5mm, and a screen mesh size of 20-50 mesh.

[0062] By setting the frequency, amplitude, and mesh size of the vibrating screen, it is possible to classify materials of different particle sizes and obtain pulverized materials with a particle size of 50-2000μm.

[0063] In specific implementation, in step S4, the specific operation of the airflow impact is as follows: a screw feeder is used to continuously convey the pre-screened fiber aerogel powder to the crushing zone, and at the same time, compressed airflow accelerated by Laval nozzles is injected into the crushing zone to collide and crush the pre-screened fiber aerogel powder to obtain airflow crushed material; the pressure of the compressed airflow is 0.35-0.7 MPa, and the operating frequency of the screw feeder is 20-50 Hz.

[0064] In specific implementation, step S5 involves the following gas-solid separation operation: The negative pressure generated by the dust collector fan is used to transport and pulverize the material via an airflow. The material flows sequentially through the fluidized bed airflow channel and the classifier wheel, then into a cyclone separator for gas-solid separation. The separated solid material flows to the bottom of the cyclone separator awaiting unloading, while the separated gaseous material is filtered by a bag filter and discharged into the atmosphere. The fluidized bed airflow channel is a multi-stage, zigzag-shaped channel with a width of 10-20 mm. The central axis of each channel section forms an angle of 30-60° with the negative pressure suction direction. The classifier wheel operates at a frequency of 5-50 Hz, the dust collector fan operates at a frequency of 20-50 Hz, and the cyclone separator's tilt angle is 30-60°. The tilt angle refers to the helix angle of the spiral blades in the cyclone separator (i.e., the angle between the tangent of the spiral blades at the cyclone separator inlet and the horizontal direction).

[0065] By adjusting parameters such as airflow pressure, classifier speed, and dust collector frequency, the particle size of the pulverized material can be controlled, achieving precise control within the range of 5-50μm.

[0066] In practice, the grading wheel adopts a multi-stage blade structure with 60-100 blade teeth. For example, it can have 60, 80, or 100 teeth.

[0067] By adjusting the angle or spacing of the classifier blades to form a multi-stage airflow plate design, extending the airflow path, and increasing the pulverization time, more precise particle size control (5-50μm) can be achieved.

[0068] In specific implementation, step S5 involves the following steps: opening the air vibration and pulse devices on the side wall of the cyclone separator and the vacuum discharge butterfly valve at the bottom outlet of the cyclone separator to discharge the separated solid material; after discharge, the pulverized and recovered fiber aerogel powder is obtained. During the discharge process, the pulse pressure is controlled at 0.3-0.5 MPa to ensure smooth discharge and prevent material adhesion and blockage in the hopper. Simultaneously, the discharge speed is controlled by a mass flow controller to maintain a dust emission concentration <20 mg / m³. 3 To avoid excessive environmental pollution.

[0069] In practice, the aerogel powder recovered from crushing is tested for performance (particle size, thermal conductivity, specific surface area) and then packaged and stored.

[0070] II. Implementation Examples

[0071] Example 1

[0072] This invention provides a method for pulverizing and recycling fiber aerogel felt, comprising the following steps:

[0073] S1. Raw material pretreatment:

[0074] S101. Collect scraps and discarded products of glass fiber aerogel felt, remove impurities and unqualified products to obtain waste aerogel felt to be recycled; and store the waste aerogel felt to be recycled in a special storage area to ensure the integrity and cleanliness of the raw materials.

[0075] S102. Conduct performance tests on the waste aerogel felt to be recycled, and determine its fiber diameter, thermal conductivity and specific surface area.

[0076] The testing methods were as follows: fiber diameter was measured using an electron microscope, thermal conductivity was measured using a Netzsch FMI446 thermal conductivity meter, and specific surface area was measured using a Bestech BSD-PS1 thermal conductivity meter.

[0077] The measured results are as follows: fiber diameter 9±1 μm, thermal conductivity 0.02028 W / (m·K), and specific surface area 768.52 m². 2 / g.

[0078] S103. Set the corresponding mechanical crushing parameters based on the performance test results.

[0079] S2. Mechanical crushing process:

[0080] A Hosokawa Micron LP-02 pulverizer was used to initially crush the waste aerogel felt to be recycled, obtaining mechanically pulverized material; during the pulverization process, the mechanical impact force was controlled at 30 N / mm. 2 The speed of the crusher is adjusted to 2000 rpm by a frequency converter; at the same time, roller crushing cutters with nano-alumina ceramic composite coating are used to crush the raw materials. The surface hardness of the roller crushing cutters is 2000 HV; the spacing between the shearing blades on the roller crushing cutters is 4 mm; and the screen mesh size in the crushing chamber of the mechanical crusher is 15 mesh.

[0081] S3. Mechanically pulverized material gas-solid separation treatment:

[0082] S301. Mechanically crushed materials are conveyed to a cyclone separator under negative pressure by a vacuum feeder for gas-solid separation. The separated solid materials flow into the bottom of the cyclone separator to await unloading. During the conveying process, the frequency of the vacuum fan is controlled at 25Hz and the vacuum feeding pressure difference is -1±(-0.5)KPa. During the separation process, a centrifugal cyclone separator is used for gas-solid separation, with the rotation speed controlled at 1800rpm and the tilt angle at 55 degrees.

[0083] S302. When unloading, open the air vibration and pulse device on the side wall of the cyclone separator and the vacuum unloading butterfly valve at the bottom outlet of the cyclone separator to unload the solid material obtained in step S301; control the pulse pressure to 0.2-0.3MPa during the unloading process.

[0084] S4. Mechanical crushing and particle size screening of materials:

[0085] A circular vibrating screen is used to perform preliminary vibration screening of the solid material obtained after gas-solid separation from mechanically pulverized materials, resulting in preliminarily screened fiber aerogel powder; before screening, the size of the circular vibrating screen is set to [value missing]. The vibrating screen has a frequency of 65Hz, an amplitude of 3mm, and a screen mesh size of 50 mesh. The obtained pre-screened fiber aerogel powder consists of aerogel particles (containing fibers) with a particle size of 50-200μm, while the material that does not pass through the screen mesh consists of fiber balls with a particle size of 1-2μm.

[0086] S5, Airflow pulverization treatment:

[0087] The pre-screened fiber aerogel powder is subjected to secondary pulverization using the principle of airflow impact to obtain air-jet pulverized material. Specifically, a screw feeder continuously conveys the pre-screened fiber aerogel powder to the pulverization zone, while compressed airflow accelerated by Laval nozzles is injected into the pulverization zone to collide and pulverize the pre-screened fiber aerogel powder, resulting in air-jet pulverized material. Before pulverization, the air pressure regulating valve is adjusted to control the compressed airflow pressure to 0.35 MPa, and the operating frequency of the screw feeder conveying the pre-screened fiber aerogel powder is 20 Hz.

[0088] S6. Gas-solid separation treatment of materials by airflow pulverization:

[0089] The dust collector uses the negative pressure generated by the dust collector fan to transport airflow and crush materials. The materials flow through the fluidized bed airflow channel and the classifier wheel in sequence, and then flow into the cyclone separator for gas-solid separation. The separated solid materials flow into the bottom of the cyclone separator to wait for unloading, while the separated gaseous materials are filtered by a bag filter (model YX-1500) and then discharged into the atmosphere.

[0090] The fluidized bed airflow channel is a multi-stage, zigzag-shaped channel with a width of 15 mm. The central axis of each channel section forms a 45° angle with the negative pressure suction direction. The classifier operates at a frequency of 50 Hz, the dust collector operates at a frequency of 20 Hz, and the classifier blades have 60 teeth. The cyclone separator has a tilt angle of 45 degrees.

[0091] S7. Product Collection and Packaging:

[0092] S701. During unloading, open the air vibration and pulse device on the side wall of the cyclone separator and the vacuum unloading butterfly valve at the bottom outlet of the cyclone separator to unload the solid material obtained in step S6. During the unloading process, control the pulse pressure to 0.3-0.4 MPa and control the unloading speed through a mass flow controller (model L-3160A) to ensure that the dust emission concentration is controlled at 18 mg / m³. 3 ;

[0093] S702. After unloading, the pulverized and recovered aerogel powder is obtained. After the performance of the aerogel powder is tested (particle size, thermal conductivity, specific surface area), it is packaged and stored.

[0094] Example 2

[0095] This invention provides a method for pulverizing and recycling fiber aerogel felt, comprising the following steps:

[0096] S1. Raw material pretreatment:

[0097] S101. Collect scraps and waste products of blended fiber (glass fiber + polyester fiber) aerogel felt, remove impurities and unqualified products to obtain waste aerogel felt to be recycled; and store the waste aerogel felt to be recycled in a special storage area to ensure the integrity and cleanliness of the raw materials.

[0098] S102. Conduct performance tests on the waste aerogel felt to be recycled, and determine its fiber diameter, thermal conductivity and specific surface area.

[0099] The testing methods were as follows: fiber diameter was measured using an electron microscope, thermal conductivity was measured using a Netzsch FMI446 thermal conductivity meter, and specific surface area was measured using a Bestech BSD-PS1 thermal conductivity meter.

[0100] The measured results are as follows: fiber diameter 9±1 μm, thermal conductivity 0.01604 W / (m·K), and specific surface area 892.68 m². 2 / g.

[0101] S103. Set the corresponding mechanical crushing parameters based on the performance test results.

[0102] S2. Mechanical crushing process:

[0103] A Hosokawa Micron LP-02 pulverizer was used to initially crush the waste aerogel felt to be recycled, obtaining mechanically pulverized material; during the pulverization process, the mechanical impact force was controlled at 20 N / mm. 2 The pulverizer speed is adjusted to 1500 rpm via a frequency converter. Simultaneously, roller press blades with a nano-alumina ceramic composite coating are used to crush the raw materials. The surface hardness of the roller press blades is 2000 HV. The spacing between the shearing blades on the roller press blades is 6 mm. The screen mesh size inside the pulverizer's crushing chamber is 8 mesh. During the crushing process, a KTY-204 temperature sensor monitors the material temperature in real time, and a closed-loop liquid nitrogen spray system continuously sprays the waste aerogel felt to control its temperature below 40℃. The liquid nitrogen flow rate during spraying is 8 L / min.

[0104] S3. Mechanically pulverized material gas-solid separation treatment:

[0105] S301. Mechanically crushed materials are conveyed to a cyclone separator under negative pressure by a vacuum feeder for gas-solid separation. The separated solid materials flow into the bottom of the cyclone separator to await unloading. During the conveying process, the frequency of the vacuum fan is controlled at 35Hz and the vacuum feeding pressure difference is -1±(-0.5)KPa. During the separation process, a centrifugal rotary separator is used for gas-solid separation, with the rotation speed controlled at 1500rpm and the tilt angle at 45 degrees.

[0106] S302. When unloading, open the air vibration and pulse device on the side wall of the cyclone separator and the vacuum unloading butterfly valve at the bottom outlet of the cyclone separator to unload the solid material obtained in step S301; control the pulse pressure to 0.3-0.4MPa during the unloading process.

[0107] S4. Mechanical crushing and particle size screening of materials:

[0108] A circular vibrating screen is used to perform preliminary vibration screening of the solid material obtained after gas-solid separation from mechanically pulverized materials, resulting in preliminarily screened fiber aerogel powder; before screening, the size of the circular vibrating screen is set to [value missing]. The vibrating screen has a frequency of 80Hz, an amplitude of 4mm, and a screen mesh size of 30 mesh. The obtained pre-screened fiber aerogel powder consists of aerogel particles (containing fibers) with a particle size of 50-400μm, while the material that does not pass through the screen mesh consists of fiber balls with a particle size of 1-2μm.

[0109] S5, Airflow pulverization treatment:

[0110] The pre-screened fiber aerogel powder is subjected to secondary pulverization using the principle of airflow impact to obtain air-jet pulverized material. Specifically, a screw feeder continuously conveys the pre-screened fiber aerogel powder to the pulverization zone, while compressed air accelerated by a Laval nozzle is injected into the pulverization zone to collide and pulverize the pre-screened fiber aerogel powder, resulting in air-jet pulverized material. Before pulverization, the air pressure regulating valve is adjusted to control the compressed air pressure to 0.7 MPa, and the operating frequency of the screw feeder conveying the pre-screened fiber aerogel powder is 50 Hz.

[0111] S6. Gas-solid separation treatment of materials by airflow pulverization:

[0112] The dust collector uses the negative pressure generated by the dust collector fan to transport airflow and crush materials. The materials flow through the fluidized bed airflow channel and the classifier wheel in sequence, and then flow into the cyclone separator for gas-solid separation. The separated solid materials flow into the bottom of the cyclone separator to wait for unloading, while the separated gaseous materials are filtered by a bag filter (model YX-1500) and then discharged into the atmosphere.

[0113] The fluidized bed airflow channel is a multi-stage, zigzag-shaped channel with a width of 15 mm. The central axis of each channel section forms a 45° angle with the negative pressure suction direction. The classifier operates at a frequency of 5 Hz, the dust collector operates at a frequency of 50 Hz, and the classifier blades have 100 teeth. The cyclone separator has a tilt angle of 45 degrees.

[0114] S7. Product Collection and Packaging:

[0115] S701. During unloading, open the air vibration and pulse device on the side wall of the cyclone separator and the vacuum unloading butterfly valve at the bottom outlet of the cyclone separator to unload the solid material obtained in step S6. During the unloading process, control the pulse pressure to 0.4-0.5MPa and control the unloading speed through a mass flow controller (model L-3160A) to ensure that the dust emission concentration is controlled at 18mg / m³. 3 ;

[0116] S702. After unloading, the pulverized and recovered aerogel powder is obtained. After the performance of the aerogel powder is tested (particle size, thermal conductivity, specific surface area), it is packaged and stored.

[0117] The performance parameters of the aerogel felt raw materials and the pulverized aerogel powder used in Examples 1 and 2 of this invention are shown in Table 1. The test standards for thermal conductivity are GB / T 10297-2015, specific surface area is GB / T 19587-2017, and particle size is GB / T 19077-2024.

[0118] Table 1. Comparison of performance parameters of aerogel felt raw materials and pulverized aerogel powder used in Examples 1 and 2.

[0119]

[0120] As can be seen from Table 1, the thermal conductivity increase rate of Examples 1 and 2 of the present invention is less than 2%; the fiber diameter change rate is less than 3%; the specific surface area decrease rate is less than 6%; and the porosity decrease rate is less than 1%. The overall performance recovery rate of the recycled material is greater than 90%. It can be seen that the recycling effect of waste aerogel felt by crushing and recycling the method of the present invention is significant.

[0121] Meanwhile, during the crushing and recycling process of this invention, the dust emission concentration is ≤20mg / m³. 3 With an energy consumption of ≤3.5kW·h / kg, it has the advantages of being environmentally friendly and having low energy consumption.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for pulverizing and recycling fiber aerogel felt, characterized in that, Includes the following steps: S1. Collect waste aerogel felt, remove impurities and substandard products to obtain waste aerogel felt to be recycled. S2. The waste aerogel felt to be recycled is mechanically crushed to obtain mechanically crushed material; S3. Perform gas-solid separation on the mechanically pulverized material, and screen the separated solid material to obtain pre-screened fiber aerogel powder. S4. The initially screened fiber aerogel powder is pulverized a second time using airflow impact to obtain airflow pulverized material; S5. Perform gas-solid separation on the air-jet pulverized material and collect the pulverized and recovered aerogel powder.

2. The method for pulverizing and recycling fiber aerogel felt according to claim 1, characterized in that, In step S2, the mechanical crushing is performed using a mechanical crusher, with the crushing speed controlled at 1000-2000 rpm and the rolling pressure of the roller cutter at 10-30 N / mm. 2 The blade spacing of the roller pressing tool is 2-8mm.

3. The method for pulverizing and recycling fiber aerogel felt according to claim 2, characterized in that, When waste aerogel felt meets any of the following conditions: (a) The waste aerogel felt contains organic components; (b) The thermal conductivity of the waste aerogel felt is <0.018 W / (m·K); (c) The specific surface area of ​​the waste aerogel felt is >800 m² 2 / g; Control the grinding speed to be between 1000 rpm and 1600 rpm, and the torque to be 10 N / mm. 2 Roller pressure ≤20N / mm 2 5mm < Roller cutting tool blade spacing ≤ 8mm; When the waste aerogel felt does not meet all the conditions in (a), (b), and (c), control the crushing speed to be 1600 rpm < crushing speed ≤ 2000 rpm and 20 N / mm. 2 < Roller pressure ≤ 30 N / mm 2 2mm≤screw press blade spacing<5mm.

4. The method for pulverizing and recycling fiber aerogel felt according to claim 1, characterized in that, In step S2, during the mechanical crushing process, a liquid nitrogen spraying system is used to continuously spray the waste aerogel felt to be recovered, with a liquid nitrogen flow rate of 5-10 L / min.

5. The method for pulverizing and recycling fiber aerogel felt according to claim 1, characterized in that, In step S3, the specific operation of gas-solid separation is as follows: mechanically crushed material is conveyed to a cyclone separator for gas-solid separation under negative pressure by a vacuum feeder; the vacuum fan frequency of the vacuum feeder is 25-35Hz, the vacuum feeding pressure difference is -1±-0.5KPa; the rotation speed of the cyclone separator is 1000-2000rpm, and the tilt angle is 30-60°.

6. The method for pulverizing and recycling fiber aerogel felt according to claim 1, characterized in that, In step S3, the screening is a vibrating screen with a frequency of 50-100Hz, an amplitude of 2-5mm, and a screen mesh size of 20-50 mesh.

7. The method for pulverizing and recycling fiber aerogel felt according to claim 1, characterized in that, In step S4, the specific operation of the airflow impact is as follows: a screw feeder is used to continuously convey the pre-screened fiber aerogel powder to the crushing zone, and at the same time, compressed airflow accelerated by Laval nozzles is injected into the crushing zone to collide and crush the pre-screened fiber aerogel powder to obtain airflow crushed material; the pressure of the compressed airflow is 0.35-0.7 MPa, and the operating frequency of the screw feeder is 20-50 Hz.

8. The method for pulverizing and recycling fiber aerogel felt according to claim 1, characterized in that, In step S5, the specific operation of gas-solid separation is as follows: the negative pressure generated by the dust removal fan is used to transport airflow to crush the material, so that it flows through the fluidized bed airflow channel and the classifier in sequence, and then flows into the cyclone separator for gas-solid separation. The separated solid material flows into the bottom of the cyclone separator to wait for unloading, and the separated gas material is filtered by the bag filter and discharged into the atmosphere. The fluidized bed airflow channel is a multi-stage zigzag channel with a width of 10-20mm. The central axis of each channel section forms an angle of 30-60° with the negative pressure suction direction. The classifier operates at a frequency of 5-50Hz, the dust removal fan operates at a frequency of 20-50Hz, and the cyclone separator is tilted at an angle of 30-60°.

9. The method for pulverizing and recycling fiber aerogel felt according to claim 8, characterized in that, The grading wheel adopts a multi-stage blade structure with 60-100 blade teeth.

10. The method for pulverizing and recycling fiber aerogel felt according to claim 8, characterized in that, In step S5, the specific collection operation is as follows: open the opening at the bottom of the cyclone separator to discharge the material, and control the outflow velocity of the powder through a mass flow controller to control the dust emission concentration to <20mg / m³. 3 After unloading, the pulverized and recycled fiber aerogel powder is obtained.

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