Device and method for microwave-infrared cooperative treatment of CFRP (carbon fiber reinforced plastic) waste

Abstract

The invention relates to the technical field of carbon fiber comprehensive treatment, in particular to a device and method for microwave and infrared cooperative treatment of CFRP waste, the device comprises a reaction box body, a cleaning system and a drying system which are sequentially connected to a track, a carbon fiber transfer frame is arranged on the track, and a liftable net cage is arranged on the carbon fiber transfer frame; the reaction box body comprises a reaction box body, the top of the reaction box body is connected with a gas system, a reaction tank is fixedly mounted at the bottom of the reaction box body, and a first through hole for the net cage to enter the reaction tank downwards is formed in the bottom wall of the reaction box body; a reaction heating mechanism is arranged on the reaction tank; molten alkali is adopted to degrade resin in the carbon fiber, the reaction temperature is lower than that in the prior art, no excessive residues exist on the surface of the regenerated carbon fiber, the process is simple, the reaction time is short, and the efficiency is higher.

Description

Technical Field

[0001] The invention relates to the technical field of comprehensive carbon fiber processing, and in particular to a device and method for co-processing CFRP waste by microwave and infrared. Background Art

[0002] Carbon fiber reinforced resin-based composite materials (CFRP) are widely used in energy facilities, aerospace, military equipment, rail transportation, sports goods and other fields due to their excellent properties such as low density, high strength, high elastic modulus, corrosion resistance and fatigue resistance. The application life of carbon fiber products in various fields is limited, and the longest does not exceed 30 years. The widespread popularization and application of carbon fiber products has led to an increase in waste year by year. CFRP waste cannot be degraded naturally. The traditional method of dealing with carbon fiber reinforced resin-based composite materials is landfill and incineration. The landfilled carbon fiber is difficult to degrade and will cause environmental pollution. The heat generated by incineration can be converted into mechanical energy or electrical energy, but incineration will produce harmful gases that pollute the environment. Many countries have promulgated laws and regulations related to the landfill and incineration of carbon fiber resin-based composite waste, restricting the landfill and incineration of waste composite materials.

[0003] At present, the treatment methods of carbon fiber waste are mainly divided into mechanical method, chemical method and thermal recovery method. The mechanical properties of carbon fiber obtained by mechanical treatment are severely damaged and the utilization value is low. The chemical method is divided into normal pressure dissolution method and super / subcritical fluid method. The treatment efficiency of normal temperature dissolution method is usually low, and a large amount of waste liquid will be generated, which will waste resources and pollute the environment. The super / subcritical fluid treatment method has high requirements for reaction equipment and is difficult to apply industrially. High-temperature pyrolysis method is the only commercial method for treating carbon fiber. Usually, the cracking is carried out under oxygen-free conditions. At this time, there will be a layer of deposited carbon on the surface of the carbon fiber, which affects the bonding of the carbon fiber and the resin. It needs to be oxidized in the air. Excessive oxidation may also affect the performance of the carbon fiber. Pyrolysis is generally carried out at 400-700 degrees Celsius, which requires a higher temperature. Oxidation treatment is also required after pyrolysis, and the treatment time is relatively long. Therefore, a method for treating carbon fiber at low temperature and high efficiency is needed. Summary of the invention

[0004] The purpose of the present invention is to provide a device and method for microwave-infrared coordinated processing of CFRP waste, so as to solve the problems of complex processing flow, long processing time, low processing efficiency and high processing temperature of existing equipment.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A device for the coordinated treatment of CFRP waste by microwave and infrared, characterized in that: it comprises a reaction box, a cleaning system and a drying system connected to a track in sequence, the track is provided with a carbon fiber transfer frame for carrying materials to move between the reaction box, the cleaning system and the drying system, and the carbon fiber transfer frame is provided with a liftable mesh box; the reaction box comprises a reaction box, the top of the reaction box is connected to a gas system, a reaction tank is fixedly installed at the bottom of the reaction box, and a first opening for the mesh box to enter the reaction tank downward is provided on the bottom wall of the reaction box; a reaction heating mechanism is provided on the reaction tank; the cleaning system comprises a cleaning box, the bottom of the cleaning box is fixedly installed with a cleaning tank, and the bottom wall of the cleaning box is provided with a second opening for the mesh box to enter the cleaning tank downward; the drying system comprises a drying box, and a drying heating mechanism is provided on the drying box; hatches for the carbon fiber transfer frame to enter and exit are respectively provided on the opposite sides of the reaction box, the cleaning box and the drying box.

[0007] As a preferred technical solution, the reaction heating mechanism includes a first infrared heating device arranged at the bottom of the reaction tank, the first infrared heating device includes an outer box body fixedly installed at the bottom of the reaction tank, the outer box body is connected to the reaction tank, an infrared heating box with a top opening is fixedly installed in the outer box body, an infrared heating tube is fixedly installed in the infrared heating box, and a reflective coating is provided on the inner wall of the infrared heating box.

[0008] As a preferred technical solution, the reaction heating mechanism also includes a first microwave heating device arranged on the side wall of the reaction tank, the first microwave heating device includes a first magnetron fixedly installed on the side of the reaction tank, and the first magnetron is connected to the reaction tank through a waveguide cavity.

[0009] As a preferred technical solution, a temperature measuring device and a pressure measuring device are installed on the reaction box.

[0010] As a preferred technical solution, the gas system includes a vacuum pump, a protective gas cylinder and a gas collection bottle, which are respectively connected to the reaction box through pipelines.

[0011] As a further improvement, an ultrasonic generator is installed on the side wall of the cleaning tank; and a second infrared heating device is provided at the bottom of the cleaning tank.

[0012] As a preferred technical solution, the drying and heating mechanism includes a second microwave heating device arranged on the top of the drying box; the drying and heating mechanism also includes a hot air circulation system, the hot air circulation system includes a hot air circulation fan installed on the top of the drying box, the air inlet end of the hot air circulation fan is connected to the drying box, the air outlet end of the hot air circulation fan is connected to the air inlet hood, the air inlet hood is fixedly installed on one side of the drying box and is connected to the drying box.

[0013] As a further improvement, an air equalizing plate is fixedly installed on one side of the drying box body close to the air inlet hood.

[0014] As a preferred technical solution, the carbon fiber transfer frame includes a base frame, the bottom of the base frame is equipped with walking wheels, a top frame driven to rise and fall by a screw lift is installed above the base frame, and the mesh box is fixedly installed on the top frame; a pressure plate for squeezing the material in the mesh box is also installed on the top frame, and the pressure plate is driven to rise and fall by a hydraulic cylinder.

[0015] A method for co-processing CFRP waste by microwave and infrared, the method comprising the following steps:

[0016] S1, feeding alkali into a reaction tank, heating the alkali through a reaction heating mechanism and keeping the alkali in a molten state;

[0017] S2, putting the waste CFRP into the mesh box on the carbon fiber transfer rack, moving the carbon fiber transfer rack into the reaction box along the track, first exhausting the air in the reaction box through the gas system, and then introducing protective gas into the reaction box through the gas system until the pressure in the reaction box reaches a set value, stopping the introduction of protective gas into the reaction box, lowering the mesh box, and immersing the waste CFRP in the mesh box in molten alkali for degradation, and collecting the gas generated by the degradation through the gas system;

[0018] S3, after the carbon fiber degradation is completed, the net box is raised, the carbon fiber transfer rack is moved into the cleaning box, and the net box is lowered, so that the carbon fiber in the net box is immersed in the cleaning tank to clean and remove the alkali remaining on the carbon fiber;

[0019] S4, after the carbon fiber cleaning is completed, the net box is raised, and the carbon fiber transfer rack is moved along the track into the drying box for heating and drying. After drying, clean regenerated carbon fiber can be obtained, and finally the carbon fiber transfer rack is moved out of the drying box;

[0020] S5, take out the carbon fiber in the net box on the carbon fiber transfer rack, and repeat steps S2-S4.

[0021] As a preferred technical solution, the alkali added in step S1 is at least one of NaOH and KOH, and the temperature at which the heating mechanism heats the alkali is 260°C-350°C; the protective gas introduced is nitrogen or argon, and the set value of the protective gas pressure introduced into the reaction box is one standard atmospheric pressure.

[0022] As a preferred technical solution, the time for immersing the waste CFRP carbon fibers in the molten alkali for degradation in step S2 is 20 min-60 min.

[0023] As a preferred technical solution, the carbon fiber in step S3 is immersed in the cleaning tank for cleaning for 30 min-90 min, the cleaning temperature is 60-90° C., and the cleaning method is ultrasonic cleaning in hot water.

[0024] As a preferred technical solution, the heating and drying temperature in step S4 is 60°C-80°C, and the drying time is 20-90 minutes.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention provides a device and method for the coordinated treatment of CFRP waste by microwave and infrared. Molten alkali is used to degrade the resin in the waste CFRP. The reaction temperature is lower than that of the existing technology. There is no residual carbon on the surface of the treated carbon fiber, and no oxidation treatment is required. The process is simple, the reaction time is short, and it is more efficient. The treated carbon fiber has good performance. Gases such as hydrogen and methane generated by resin degradation can be used as fuel to avoid waste of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0028] Figure 1 It is a structural schematic diagram of an embodiment of the present invention;

[0029] Figure 2 This is a schematic structural diagram of an infrared heating tube according to an embodiment of the present invention;

[0030] Figure 3 It is a structural schematic diagram of a red first infrared heating device according to an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the reaction box structure of an embodiment of the present invention;

[0032] Figure 5 It is a structural schematic diagram of a reaction box and a cleaning system according to an embodiment of the present invention;

[0033] Figure 6 It is a structural schematic diagram of a drying system according to an embodiment of the present invention;

[0034] Figure 7 This is a schematic structural diagram of a carbon fiber transport frame according to an embodiment of the present invention;

[0035] Figure 8 A schematic structural diagram of a base frame according to an embodiment of the present invention;

[0036] Fig. 9 The waste CFRP used in Example 1;

[0037] Fig.10 This is a physical picture of the regenerated carbon fiber in Example 1;

[0038] Fig.11 is a scanning electron microscope image of the regenerated carbon fiber in Example 1;

[0039] In the figure: 1-reaction box; 101-first pressure sensor; 102-first temperature sensor; 103-first magnetron; 104-gas collection device valve; 105-protective gas valve; 106-reaction box hatch; 2-reaction tank; 201-reaction tank water inlet valve; 202-reaction tank sewage valve; 3-first infrared heating device; 301-quartz sleeve; 302-infrared heating wire vacuum chamber; 303-infrared heating wire; 304-electrode vacuum chamber; 305-electrode; 306-infrared heating box; 307-power box; 308-outer box; 4-PLC control panel; 5-cleaning box; 501-exhaust hole; 502-cleaning box hatch; 6-cleaning tank; 601-cleaning tank water inlet valve; 602-cleaning tank sewage valve; 603- Ultrasonic generator; 604-second infrared heating device; 7-drying box; 701-drying box door; 702-second magnetron; 703-second pressure sensor; 704-second temperature sensor; 705-hot air circulation fan; 706-gas equalizing plate; 707-inlet pipeline; 708-outlet pipeline; 709-inlet hood; 8-track; 9-vacuum pump; 10-protective gas cylinder; 11-primary gas collection bottle; 12-secondary gas collection bottle; 13-carbon fiber transfer rack; 1301-screw; 1302-commutator; 1303-screw lift; 1304-drive shaft; 1305-travel wheel; 1306-net box; 1307-lifting motor; 1308-hydraulic cylinder; 1309-pressing plate; 1310-bottom frame; 1311-top frame. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0041] like Figures 1 to 10 As shown, a device for microwave-infrared coordinated processing of CFRP waste includes a reaction box, a cleaning system and a drying system which are sequentially connected to a circular track 8, a carbon fiber transfer frame 13 for carrying materials between the reaction box, the cleaning system and the drying system is provided on the track 8, and a liftable mesh box 1306 is provided on the carbon fiber transfer frame 13.

[0042] Specifically, the cage 1306 can be raised and lowered by an electric push rod or a hydraulic cylinder. Figure 7 and Figure 8As shown, the carbon fiber transport frame 13 includes a base frame 1310, and the four corners of the bottom of the base frame 1310 are respectively installed with walking wheels 1305, which are convenient for moving on the track 8; the top of the base frame 1310 is installed with four screw lifts 1303 distributed in a rectangular array through bolts, and the top of the screw lift 1303 is rotatably installed with a screw nut, and a screw 1301 extending upward is screwed into the screw nut, and the upper ends of the four screws 1301 are fixedly installed with a top frame 1311, and the top frame 1311 The bottom is fixed with a net box 1306 by an extension rod extending downward, the upper end of the net box 1306 is open and a plurality of water-permeable holes are evenly distributed on its side wall; the screw nut is sleeved with a commutator 1302 located at the top of the screw lift 1303, and a transmission shaft 1304 is connected between the two commutators 1302 facing each other and between the two commutators 1302 located at the rear side, respectively, and the transmission shaft 1304 located between the two commutators 1302 at the rear side is connected to the lifting motor 1307. The two ends of the transmission shaft 1304 are respectively connected to the corresponding screw nuts through the commutator 1302, and the lifting motor 1307 can drive the transmission shaft 1304 to rotate, and the transmission shaft 1304 transmits power to the screw nuts on the screw lifts 1303 at both ends, thereby realizing the synchronous lifting of the four screws 1301, and then the screws 1301 drive the top frame 1311 and the net box 1306 to rise or fall. In addition, a pressing plate 1309 for squeezing the material in the net box 1306 is installed on the top frame 1311. The pressing plate 1309 is driven to rise and fall by the hydraulic cylinder 1308. The cylinder body of the hydraulic cylinder 1308 is fixed to the bottom of the top frame 1311 by bolts. The piston rod of the hydraulic cylinder 1308 extends downward and is fixedly connected to the pressing plate 1309. There are also multiple water-permeable holes evenly distributed on the pressing plate 1309. The hydraulic cylinder 1308 extends to drive the pressing plate 1309 downward to squeeze the material in the net box 1306, thereby promoting the dehydration of the material.

[0043] like Figure 4 and Figure 5 As shown, the reaction system includes a reaction box 1, the bottom wall of the reaction box 1 is flush with the top of the track 8, and the reaction box hatches 106 for the carbon fiber transport rack 13 to enter and exit are respectively provided on both sides of the reaction box 1 along the extension direction of the track 8, and the reaction box hatches 106 are driven to rise and fall by a hydraulic mechanism. A control device is provided on the side wall of the reaction box 1, and the control device is specifically a PLC control panel 4. The PLC control panel 4 controls the entire system through C language programming, and the interaction is realized through the screen on the PLC control panel 4. A temperature measuring device and a pressure measuring device are installed on the top of the reaction box 1. The temperature measuring device is a first temperature sensor 102, and the pressure measuring device is a first pressure sensor 101. The first temperature sensor 102, the first pressure sensor 101 and the PLC control panel 4 are connected, and the temperature and pressure indications in the reaction box 1 are directly displayed on the PLC control panel 4.

[0044] A reaction tank 2 for containing alkali solution is fixedly installed at the bottom of the reaction box 1, and a first opening for the net box 1306 to enter the reaction tank 2 downward is provided on the bottom wall of the reaction box 1. A reaction tank water inlet valve 201 and a reaction tank sewage valve 202 are provided on the side wall of the reaction tank 2 to facilitate cleaning of the inside of the reaction tank 2. The reaction tank sewage valve 202 is an electric stainless steel flange ball valve, and the switch of the reaction tank sewage valve 202 is controlled by the PLC control panel 4.

[0045] The reaction tank 2 is provided with a reaction heating mechanism, which includes a first infrared heating device 3 arranged at the bottom of the reaction tank 2. Figure 2 and Figure 3 As shown, the first infrared heating device 3 includes an outer box 308 fixedly installed at the bottom of the reaction tank 2, the outer box 308 is connected to the bottom of the reaction tank 2, an infrared heating box 306 with an open top is fixedly installed in the outer box 308, and a plurality of infrared heating tubes evenly spaced are fixedly installed in the infrared heating box 306; the infrared heating tube specifically includes a quartz sleeve 301 located outside, an infrared heating wire vacuum cavity 302 located in the middle and electrode vacuum cavities 304 located at both ends are arranged in the quartz sleeve 301, an infrared heating wire 303 is placed in the infrared heating wire vacuum cavity 302, and the two ends of the infrared heating wire 303 are respectively connected to electrodes 305, and the two electrodes 305 are respectively placed in the electrode vacuum cavities 304 at both ends of the infrared heating tube, and power boxes 307 are respectively arranged on opposite sides of the infrared heating box 306, and the electrodes 305 at both ends of the infrared heating tube are respectively connected to the corresponding power boxes 307. In addition, a reflective coating is provided on the inner wall of the infrared heating box 306.

[0046] The reaction heating mechanism also includes a first microwave heating device disposed on the side wall of the reaction tank 2. The first microwave heating device includes a first magnetron 103 fixedly mounted on the side of the reaction tank 2. The first magnetron 103 is connected to the reaction tank 2 through a waveguide cavity. The start and stop of the first magnetron 103 is controlled by a PLC control panel 4. In this embodiment, Figure 4 and Figure 5 As shown, four first magnetrons 103 distributed in a rectangular array are respectively installed on opposite sides of the reaction tank 2, which has a higher heating efficiency.

[0047] like Figure 1 As shown, the reaction box 1 is connected to the gas system. Specifically, a protective gas valve 105 and a gas collection device valve 104 are provided on the top of the reaction box 1. The protective gas valve 105 is connected to the vacuum pump 9 and the protective gas cylinder 10 through pipelines, respectively. The gas collection device valve 104 is connected to the primary gas collection bottle 11 through a pipeline. The primary gas collection bottle 11 is also connected in series with a secondary gas collection bottle 12 to collect the gas generated by the degradation of the carbon fiber.

[0048] like Figure 1 and Figure 5 As shown, the cleaning system includes a cleaning box 5, a vent hole 501 is provided on the top of the cleaning box 5, the bottom wall of the cleaning box 5 is flush with the top of the track 8, and cleaning box hatches 502 for the carbon fiber transfer rack 13 to enter and exit are provided on both sides of the cleaning box 5 along the extension direction of the track 8, and the cleaning box hatches 502 are driven up and down by a hydraulic mechanism. A cleaning tank 6 for holding clean water is fixedly installed at the bottom of the cleaning box 5, and a second opening for the net box 1306 to enter the cleaning tank 6 downward is provided on the bottom wall of the cleaning box 5. A cleaning tank water inlet valve 601 and a cleaning tank sewage valve 602 are provided on the side wall of the cleaning tank 6. The cleaning tank sewage valve 602 is a high-temperature resistant electric flange ball valve. The switch of the cleaning tank sewage valve 602 is controlled by the PLC control panel 4 to realize the water change of the cleaning tank 6. An ultrasonic generator 603 is installed on the side wall of the cleaning tank 6, and a second infrared heating device 604 is installed at the bottom of the cleaning tank 6 to realize ultrasonic cleaning of the carbon fiber in hot water. The second infrared heating device 604 has the same structure as the first infrared heating device 3 .

[0049] like Figure 1 and Figure 6 As shown, the drying system includes a drying box 7, the bottom wall of the drying box 7 is flush with the top of the track 8, a supporting box is fixedly installed at the bottom of the drying box 7, and drying box doors 701 for the carbon fiber transport rack 13 to enter and exit are respectively provided on both sides of the drying box 7 along the extension direction of the track 8, and the drying box doors 701 are driven up and down by a hydraulic mechanism. A second pressure sensor 703 and a second temperature sensor 704 are installed on the top of the drying box 7, and the second pressure sensor 703, the second temperature sensor 704 and the PLC control panel 4 are connected.

[0050] The drying box 7 is provided with a drying heating mechanism. The drying heating mechanism includes a second microwave heating device arranged on the top of the drying box 7, and the second microwave heating device includes four second magnetrons 702 fixedly installed on the top of the drying box 7 and distributed in a rectangular array. The second magnetrons 702 are connected to the drying box 7 through a waveguide cavity, and the start and stop of the second magnetrons 702 are controlled by a PLC control panel 4. The drying and heating mechanism also includes a hot air circulation system, which includes a hot air circulation fan 705 installed on the top of the drying box 7 by bolts, the air inlet end of the hot air circulation fan 705 is connected to the top side of the drying box 7 through an air inlet pipe 707, and the air outlet end of the hot air circulation fan 705 is connected to an air inlet hood 709 through an air outlet pipe 708. The air inlet hood 709 is fixedly installed on one side of the drying box 7 and is connected to the drying box 7. The air inlet end of the air inlet pipe 707 is located on the side of the top of the drying box 7 away from the air inlet hood 709. The hot air circulation fan 705 extracts the air in the drying box 7 and re-injects it into the drying box 7 through the air inlet hood 709, thereby accelerating the air flow in the drying box 7. In addition, an air distribution plate 706 is fixedly installed on one side of the drying box 7 near the air inlet hood 709 by bolts. The air distribution plate 706 has multiple air holes evenly distributed on it, which is conducive to the uniform distribution of the hot air entering through the air inlet hood 709 in the drying box 7.

[0051] A method for co-processing CFRP waste by microwave and infrared, the method comprising the following steps:

[0052] S1: Add alkali into the reaction tank 2, close the reaction box door 106, operate the PLC control panel 4, start the first infrared heating device 3 at the bottom of the reaction box, heat the alkali in the reaction tank 2, and after heating to a molten state, start the insulation program to keep the alkali in a molten state;

[0053] S2: Open the reaction box hatch 106, put the waste CFRP into the net box 1306 on the carbon fiber transfer rack 13, move the carbon fiber transfer rack 13 into the reaction box 1 along the track 8, close the reaction box hatch 106, open the vacuum pump 9 to exhaust the air in the reaction box 1, and after exhausting the air, open the protective gas cylinder 10 to pass the protective gas into the reaction box 1 until the pressure in the reaction box 1 reaches the set value, stop passing the protective gas into the reaction box 1, start the first microwave heating device on the side of the reaction tank 2, lower the net box 1306, and immerse the waste CFRP in the net box 1306 in the molten alkali for degradation. The gas generated by the degradation enters the primary gas collection bottle 11 and the secondary gas collection bottle 12 through the pipeline;

[0054] S3: After the pyrolysis of waste CFRP is completed, raise the wire mesh box 1306, lower the pressing plate 1309 to squeeze out the lye in the carbon fiber. After squeezing out the lye in the carbon fiber, raise the pressing plate 1309, open the reaction chamber door 106, open the cleaning box door 502, move the carbon fiber transfer rack 13 into the cleaning box body 5, lower the wire mesh box 1306, immerse the carbon fiber in the wire mesh box 1306 into the cleaning tank 6, and at the same time lower the pressing plate 1309 into the cleaning tank 6 to clean the lye remaining on the pressing plate 1309; then raise the pressing plate 1309, close the cleaning box door 502, clean and remove the lye remaining on the carbon fiber. After the cleaning is completed, raise the wire mesh box 1306 and lower the pressing plate 1309 to squeeze out the moisture remaining in the carbon fiber;

[0055] S4: After the carbon fiber cleaning is completed, open the cleaning box door 502, open the drying box door 701, move the carbon fiber transfer rack 13 into the drying box body 7 along the track 8, close the drying box door 701, start the second microwave heating device and the hot air circulation fan 705, set the heating temperature of the second microwave heating device, heat and dry the carbon fiber. After the drying is completed, clean regenerated carbon fiber can be obtained. Finally, open the drying box door 701 and move the carbon fiber transfer rack 13 out of the drying box body 7;

[0056] S5: Take out the regenerated carbon fiber in the wire mesh box 1306 on the carbon fiber transfer rack 13, and repeat steps S2 - S4 for the next round of regeneration work.

[0057] The alkali added in step S1 is NaOH or KOH or a mixture of both. The heating temperature of the alkali by the first microwave heating device is 260°C - 350°C; the protective gas introduced is nitrogen or argon, and the set value of the pressure of the protective gas introduced into the reaction box body 1 is one standard atmosphere.

[0058] The time for the carbon fiber in step S2 to be immersed in the molten alkali for degradation is 20 min - 60 min.

[0059] The time for the carbon fiber in step S3 to be immersed in the cleaning tank 6 for cleaning is 30 min - 90 min, the cleaning temperature is 60 - 90°C, and the cleaning method is ultrasonic cleaning in hot water.

[0060] The temperature for the second microwave heating device to heat and dry the carbon fiber in step S4 is 60°C - 80°C, and the drying time is 20 - 90 min.

[0061] The reaction system, the cleaning system, and the drying system are independent of each other and do not affect each other during operation, so they can work simultaneously. When the alkali in the reaction tank 2 is consumed to be insufficient for pyrolysis, alkali is added to the reaction tank 2, and pyrolysis can continue after the alkali is heated to a molten state. After the pyrolysis work is completed, water can be injected into the reaction tank 2 through the reaction tank water inlet valve 201 on the side wall of the reaction tank 2 for cleaning, and after the cleaning is completed, the sewage can be discharged through the reaction tank sewage valve 202.

[0062] Example 1

[0063] 15 kg of industrial KOH was weighed and fed into the reaction tank 2. The reaction box hatch 106 was closed. The PLC control panel 4 was operated to set the heating temperature to 340° C. The first infrared heating device 3 was started to heat the alkali in the reaction tank 2. After heating to a molten state, the insulation program was started to keep the alkali in a molten state.

[0064] Open the reaction box hatch 106, weigh 5 kg of scraps generated during the processing of carbon fiber products (such as Fig. 9 As shown), the carbon fiber is sent into the net box 1306 on the carbon fiber transfer rack 13, the carbon fiber transfer rack 13 is moved into the reaction box 1 along the track, the reaction box hatch 106 is closed, the vacuum pump is turned on to exhaust the air in the box, after exhausting the air, the protective gas cylinder 10 is opened to pass argon into the reaction box 1 until the pressure in the reaction box 1 reaches 1Mpa, the protective gas is stopped from passing into the reaction box 1, the first microwave heating device on the side of the reaction tank 2 is started, the pressure plate 1309 is lowered to make the pressure plate 1309 flush with the upper end of the net box 1306, the net box 1306 is lowered, and the carbon fiber in the net box 1306 is immersed in molten alkali for degradation, and the gas generated by the degradation enters the primary gas collection bottle 11 and the secondary gas collection bottle 12 through the pipeline. The degradation time of the carbon fiber in the reaction tank is 60min.

[0065] After the pyrolysis of waste CFRP is completed, the net box 1306 is raised, the pressure plate 1309 is lowered to squeeze out the alkali solution in the carbon fiber, and the pressure plate 1309 is raised after squeezing out the alkali solution in the carbon fiber, the reaction box hatch 106 is opened, the cleaning box hatch 502 is opened, and the carbon fiber transfer rack 13 is moved to the cleaning box 5. Operate the PLC control panel 4, set the heating temperature to 80°C, start the second infrared heating device 604, heat the water in the cleaning tank 6, and keep it warm after heating to the set temperature. Lower the pressure plate 1309 so that the pressure plate 1309 is flush with the upper end of the net box 1306, lower the net box 1306, immerse the carbon fiber in the net box 1306 in the cleaning tank 6, start the ultrasonic generator 603, clean the alkali on the carbon fiber, and the cleaning time is 70 minutes. After the cleaning is completed, turn off the ultrasonic generator 603, raise the net box 1306 and lower the pressure plate 1309, squeeze and remove the water remaining in the carbon fiber.

[0066] After the carbon fiber cleaning is completed, open the cleaning box door 502, open the drying box door 701, move the carbon fiber transfer rack 13 into the drying box 7 along the track, close the drying box door 701, start the second microwave heating device and the hot air circulation fan, set the heating temperature of the second microwave heating device to 80°C, heat and dry the carbon fiber for 90 minutes, and obtain clean regenerated carbon fiber after drying. Finally, open the drying box door 701, move the carbon fiber transfer rack out of the drying box 7, and obtain the regenerated carbon fiber material.

[0067] Example 2

[0068] Weigh 15 kg of a mixture of industrial NaOH and industrial KOH (the mass ratio of NaOH to KOH is 1:1) and put it into the reaction tank 2. Close the reaction box hatch 106. Operate the PLC control panel 4 to set the heating temperature to 300° C. Start the first infrared heating device 3 to heat the alkali in the reaction tank 2. After heating to a molten state, start the insulation program to keep the alkali in a molten state.

[0069] Open the reaction box hatch 106, send a 30cm×20cm piece of waste prepreg into the mesh box 1306 on the carbon fiber transfer rack 13, move the carbon fiber transfer rack 13 into the reaction box 1 along the track, close the reaction box hatch 106, turn on the vacuum pump to exhaust the air in the box, and after exhausting the air, open the protective gas cylinder 10 to pass argon into the reaction box until the pressure in the reaction box reaches 1Mpa, stop passing protective gas into the reaction box 1, start the first microwave heating device on the side of the reaction tank 2, lower the pressure plate 1309 so that the pressure plate 1309 is flush with the upper end of the mesh box 1306, lower the mesh box 1306, and immerse the carbon fiber in the mesh box 1306 in molten alkali for degradation. The gas generated by the degradation enters the primary gas collection bottle 11 and the secondary gas collection bottle 12 through the pipeline. The degradation time of the carbon fiber in the reaction tank is 30 minutes.

[0070] After the pyrolysis reaction of waste CFRP is completed, the net box 1306 is raised, the pressure plate 1309 is lowered to squeeze out the alkali solution in the carbon fiber, and the pressure plate 1309 is raised after squeezing out the alkali solution in the carbon fiber, the reaction box hatch 106 is opened, the cleaning box hatch 502 is opened, and the carbon fiber transfer rack 13 is moved to the cleaning box 5. Operate the PLC control panel 4, set the heating temperature to 70°C, start the second infrared heating device 604, heat the water in the cleaning tank 6, and keep it warm after heating to the set temperature. Lower the pressure plate 1309 so that the pressure plate 1309 is flush with the upper end of the net box 1306, lower the net box 1306, immerse the carbon fiber in the net box 1306 in the cleaning tank 6, start the ultrasonic generator 603, clean the alkali on the carbon fiber, and the cleaning time is 30 minutes. After the cleaning is completed, turn off the ultrasonic generator 603, raise the net box and lower the pressure plate, and squeeze to remove the moisture remaining in the carbon fiber.

[0071] After the carbon fiber cleaning is completed, open the cleaning chamber door 502 and the drying chamber door 701. Move the carbon fiber transfer rack 13 into the drying box body 7 along the track, close the drying chamber door 701, start the second microwave heating device and the hot air circulation fan, set the heating temperature of the second microwave heating device to 70 °C, heat and dry the carbon fiber. The drying time is 60 min. After drying, clean recycled carbon fiber can be obtained. Finally, open the drying chamber door 701 and move the carbon fiber transfer rack out of the drying box body 7.

[0072] The physical picture of the carbon fiber regenerated in Example 1 is as Fig.10 shown, and the scanning electron microscope picture of the regenerated carbon fiber is as Fig.11 shown. The surface of the regenerated carbon fiber is clean, without resin residue and pyrolytic carbon generation. Compared with the existing pyrolysis method, the temperature of this treatment method is lower. There is no deposited carbon on the surface of the regenerated carbon fiber, and no oxidation treatment is required. Clean carbon fiber can be obtained by one-step pyrolysis, and the process flow is simpler. This device has no requirements for the shape of the treatment object, has strong adaptability, can process carbon fiber plates, and can also process broken carbon fibers, and can realize continuous batch processing.

[0073] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present invention and do not limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A device for co-processing CFRP waste by microwave and infrared, characterized in that: It includes a reaction system, a cleaning system and a drying system connected to a track in sequence, the track is provided with a carbon fiber transfer frame for carrying materials to move between the reaction system, the cleaning system and the drying system, and the carbon fiber transfer frame is provided with a liftable mesh box; The reaction system comprises a reaction box, the top of which is connected to a gas system, a reaction tank is fixedly installed at the bottom of the reaction box, a first opening is provided on the bottom wall of the reaction box for the mesh box to enter the reaction tank downwards; a reaction heating mechanism is provided on the reaction tank; The cleaning system comprises a cleaning box, a cleaning tank is fixedly installed at the bottom of the cleaning box, and a second opening for the net box to enter the cleaning tank downward is provided on the bottom wall of the cleaning box; The drying system comprises a drying box, and the drying box is provided with a drying heating mechanism; The reaction box, the cleaning box and the drying box are provided with hatches for the carbon fiber transport rack to enter and exit respectively on opposite sides.

2. The device for microwave and infrared coordinated treatment of CFRP waste as claimed in claim 1, characterized in that: The reaction heating mechanism includes a first infrared heating device arranged at the bottom of the reaction tank, the first infrared heating device includes an outer box body fixedly installed at the bottom of the reaction tank, the outer box body is connected to the reaction tank, an infrared heating box with a top opening is fixedly installed in the outer box body, an infrared heating tube is fixedly installed in the infrared heating box, and a reflective coating is provided on the inner wall of the infrared heating box.

3. The device for microwave and infrared coordinated treatment of CFRP waste as claimed in claim 1, characterized in that: The reaction heating mechanism also includes a first microwave heating device arranged on the side wall of the reaction tank, the first microwave heating device includes a first magnetron fixedly installed on the side of the reaction tank, and the first magnetron is connected to the reaction tank through a waveguide cavity.

4. The device for microwave and infrared coordinated treatment of CFRP waste as claimed in claim 1, characterized in that: The gas system comprises a vacuum pump, a protective gas cylinder and a gas collection bottle which are respectively connected to the reaction box through pipelines.

5. The device for microwave and infrared coordinated treatment of CFRP waste as claimed in claim 1, characterized in that: An ultrasonic generator is installed on the side wall of the cleaning tank; and a second infrared heating device is arranged at the bottom of the cleaning tank.

6. The device for microwave and infrared coordinated treatment of CFRP waste as claimed in claim 1, characterized in that: The drying and heating mechanism includes a second microwave heating device arranged on the top of the drying box; the drying and heating mechanism also includes a hot air circulation system, which includes a hot air circulation fan installed on the top of the drying box, the air inlet end of the hot air circulation fan is connected to the drying box, and the air outlet end of the hot air circulation fan is connected to an air inlet hood, which is fixedly installed on one side of the drying box and communicated with the drying box.

7. The device for microwave and infrared coordinated treatment of CFRP waste as claimed in claim 1, characterized in that: The carbon fiber transfer frame includes a base frame, the bottom of the base frame is equipped with walking wheels, the top frame driven to rise and fall by a screw lift is installed above the base frame, and the net box is fixedly installed on the top frame; a pressure plate for squeezing the material in the net box is also installed on the top frame, and the pressure plate is driven to rise and fall by a hydraulic cylinder.

8. A method for microwave-infrared co-processing CFRP waste using the microwave-infrared co-processing device for CFRP waste according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: S1, feeding alkali into a reaction tank, heating the alkali through a reaction heating mechanism and keeping the alkali in a molten state; S2, putting the waste CFRP into the mesh box on the carbon fiber transfer rack, moving the carbon fiber transfer rack into the reaction box along the track, first exhausting the air in the reaction box through the gas system, and then introducing protective gas into the reaction box through the gas system until the pressure in the reaction box reaches a set value, stopping the introduction of protective gas into the reaction box, lowering the mesh box, and immersing the waste CFRP in the mesh box in molten alkali for degradation, and collecting the gas generated by the degradation through the gas system; S3, after the degradation of the composite material is completed, the net box is raised, the carbon fiber transfer rack is moved into the cleaning box, and the net box is lowered, so that the carbon fiber in the net box is immersed in the cleaning tank to clean and remove the alkali remaining on the carbon fiber; S4, after cleaning, the net box is raised, and the carbon fiber transfer rack is moved along the track into the drying box for heating and drying. After drying, clean regenerated carbon fiber can be obtained, and finally the carbon fiber transfer rack is moved out of the drying box; S5, take out the carbon fiber in the net box on the carbon fiber transfer rack, and repeat steps S2-S4.

9. The method for microwave-infrared coordinated treatment of CFRP waste as claimed in claim 8, characterized in that: The alkali added in step S1 is at least one of NaOH and KOH, and the temperature at which the alkali is heated by the reaction heating mechanism is 260° C.-350° C.; the protective gas introduced is nitrogen or argon, and the set value of the protective gas pressure introduced into the reaction box is a standard atmospheric pressure.

10. The method for microwave-infrared coordinated treatment of CFRP waste as claimed in claim 8, characterized in that: The time for immersing the waste CFRP in molten alkali for degradation in step S2 is 20min-60min; the time for immersing the carbon fiber in the cleaning tank for cleaning in step S3 is 30min-90min, the cleaning temperature is 60-90°C, and the cleaning method is ultrasonic cleaning in hot water; the temperature for heating and drying in step S4 is 60°C-80°C, and the drying time is 20-90min.

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