Method for recycling waste agricultural film based on double-frequency electromagnetic induction heating process

Abstract

The invention relates to the field of waste agricultural film recycling, in particular to a method for recycling waste agricultural films based on a double-frequency electromagnetic induction heating process. Through the steps of classified collection, pretreatment, double-frequency electromagnetic induction heating, extrusion granulation, cooling, pelletizing and the like, the temperature of different parts of the charging barrel can be accurately controlled, so that waste agricultural films are uniformly heated in the whole plasticizing process, the problems of high-temperature burning and low-temperature solidification are effectively avoided, the quality and performance of regenerated plastic particles are remarkably improved, and the production cost is reduced. According to the process, open fire and waste gas are not generated, environmental pollution is reduced, due to the fact that the heating speed is high, the material oxidation and decomposition degree is reduced, generation of harmful substances is reduced, the environmental protection requirement is met, and sustainable development is facilitated.

Description

Technical Field

[0001] The invention relates to the field of recycling of waste agricultural films, and in particular to a method for recycling waste agricultural films based on a dual-frequency electromagnetic induction heating process. Background Art

[0002] With the acceleration of agricultural modernization, the use of agricultural plastic films has increased dramatically. However, waste agricultural films are often discarded or simply landfilled after use. Due to its difficulty in natural degradation, it has caused serious pollution to the soil, water and ecological environment, which is called "white pollution". Therefore, how to effectively recycle waste agricultural films has become an environmental and resource issue that needs to be solved urgently.

[0003] Traditional methods for recycling waste agricultural films mainly include mechanical recycling and chemical recycling. The mechanical recycling method usually involves simply cleaning and crushing the waste agricultural films and then directly extruding and granulating them. However, this method has problems such as uneven heating, high energy consumption, and unstable product quality. The chemical recycling method requires the use of a large amount of chemical reagents, and the treatment process is complicated, costly, and prone to secondary pollution.

[0004] Traditional waste agricultural film recycling and granulation processes mostly use resistance heating to heat the barrel to achieve melting and plasticization of the agricultural film. This heating method has many disadvantages. First, its energy utilization rate is low. Heat is mainly transferred from the electric heating ring to the barrel through contact conduction. A large amount of heat on the outside of the barrel is lost to the air, causing serious heat conduction losses and a huge waste of energy. Secondly, it is difficult to achieve uniform temperature distribution by resistance heating. The temperature difference between different parts of the barrel is large, which makes it easy for the agricultural film to be locally overheated and burned or locally solidified at low temperature during the plasticization process, seriously affecting the quality and performance of the recycled plastic particles. Furthermore, the traditional resistance heating method also has environmental pollution problems. The ambient temperature will increase significantly during the heating process, and the resistance wire is easy to oxidize under high temperature conditions, which not only shortens the service life of the heating equipment, but also increases maintenance costs and downtime. In addition, the temperature control accuracy of the traditional process is poor, which is difficult to meet the requirements of precise temperature control at different stages in the process of waste agricultural film recycling and granulation, which is not conducive to the production of high-quality and stable performance recycled plastic particles.

[0005] Therefore, the development of a new type of waste agricultural film regeneration and granulation process has extremely important practical significance. The waste agricultural film regeneration and granulation process based on dual-frequency electromagnetic induction heating of the present invention came into being, which is expected to effectively solve the above problems and open up a new way for the recycling of waste agricultural film. Summary of the invention

[0006] The purpose of the present invention is to overcome the above problems and provide a method for recycling waste agricultural film based on a dual-frequency electromagnetic induction heating process. To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A method for recycling waste agricultural film based on a dual-frequency electromagnetic induction heating process, specifically comprising the following steps:

[0008] 1) Classification and collection: waste agricultural films are classified and collected according to their materials and thickness. The materials include polyethylene and polyvinyl chloride;

[0009] 2) Pretreatment, which includes cleaning, drying, crushing, magnetic separation, and screening. The cleaning adopts multi-stage cleaning, and the drying needs to control the temperature. The waste agricultural film is crushed by a crusher, the metal impurities are removed by magnetic separation, and the larger particles of impurities are removed by screening. The waste agricultural film is pretreated to obtain agricultural film fragments;

[0010] 3) Dual-frequency electromagnetic induction heating: select appropriate dual-frequency electromagnetic induction heating equipment according to the classification, set the power, frequency range, and temperature control parameters of the equipment, use low and medium frequencies for agricultural films made of polyethylene, and use high frequencies for agricultural films made of polyvinyl chloride. Add agricultural film fragments into the heating chamber of the dual-frequency electromagnetic induction heating equipment, pass high-frequency current into the induction coil at the feeding end, and low-frequency current acts on the induction coil at the discharging end. During the heating process, the PLC temperature intelligent control system monitors the temperature in the barrel in real time to obtain molten material;

[0011] 4) Extrusion granulation, preheating the extruder, sending the molten material to the feeding port of the preheated extruder, the extruder includes a feeding section, a compression section, and a homogenization section, and different sections require different temperatures. The filter at the outlet of the extruder filters impurities and extrude the material through the die of the extruder to form a strip material;

[0012] 5) Cooling and pelletizing: the strip material enters the cooling water tank for cooling. The cooled strip material is cut into granular material by a pelletizer, and the granular material is collected and packaged.

[0013] As an improvement, it is characterized in that the electromagnetic induction heating equipment is set according to the frequency range, the low frequency is 1-5kHz, the medium frequency is 10-30kHz, and the high frequency is greater than 40kHZ.

[0014] As an improvement, the dual-frequency electromagnetic induction heating equipment has the function of adjusting the frequency combination. For agricultural film made of polyethylene, a lower frequency is selected to quickly increase the overall temperature in the initial heating stage, and then switched to a medium frequency in the plasticizing stage to improve heating efficiency.

[0015] As an improvement, the temperature of the feeding section is controlled at 120-150°C, the temperature of the compression section is 150-180°C, the temperature of the homogenization section is 180-220°C, and the temperature control accuracy is within ±5°C.

[0016] As an improvement, a screw is provided in the dual-frequency electromagnetic induction heating device, and the screw speed is 30-60 revolutions per minute.

[0017] As an improvement, the cleaning includes preliminary rinsing, soaking, and re-rinsing. The waste agricultural film is initially rinsed with a high-pressure water gun, and the agricultural film is soaked in a cleaning solution containing an appropriate amount of surfactant. The cleaning solution is fully contacted with the agricultural film through a stirring device. The soaking time is controlled at 15-30 minutes, and then the high-pressure water gun is used again to rinse to ensure that the surface of the agricultural film is clean. The drying temperature is controlled at 60-80℃, and the moisture content of the agricultural film is reduced to 2%-5% after drying. The size of the fragments after crushing is controlled between 5-20mm.

[0018] As an improvement, the filter screen is 100-200 mesh, the cooling water temperature is generally 10-30°C, and the diameter of the granular material is 2-5mm.

[0019] As an improvement, choose appropriate dual-frequency electromagnetic induction heating equipment according to the scale of the production line. For a small-scale waste agricultural film recycling and granulation production line with a daily output of 1-2 tons, choose equipment with a power of 30-50kW. For a medium-sized production line with a daily output of 3-5 tons, choose equipment with a power of 50-100kW. For a large-scale production line with a daily output of more than 5 tons, choose equipment with a power of more than 100kW.

[0020] The advantages of the present invention are:

[0021] 1. Compared with the traditional resistance heating method, the energy-saving effect of the present invention is very significant. The dual-frequency electromagnetic induction heating method of the present invention makes the metal barrel itself generate heat, and a certain thickness of heat insulation material is wrapped on the outside of the barrel, which effectively reduces heat loss and improves thermal efficiency.

[0022] 2. The dual-frequency electromagnetic induction heating process of the present invention can accurately control the temperature of different parts of the barrel through segmented temperature control settings, so that the waste agricultural film is evenly heated during the entire plasticizing process, effectively avoiding the problems of high-temperature burning and low-temperature solidification, and significantly improving the quality and performance of recycled plastic particles.

[0023] 3. The process of the present invention does not produce open flames and waste gas, thus reducing environmental pollution. Moreover, due to the fast heating speed, the degree of oxidation and decomposition of materials is reduced, the generation of harmful substances is reduced, the process meets environmental protection requirements, and is conducive to sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of the electromagnetic heating coil model in Example 1.

[0025] Figure 2 This is a schematic diagram of the PLC temperature intelligent control system in Example 1.

[0026] The symbols in the figure are:

[0027] 1. Screw; 2. Barrel; 3. Plastic; 4. Thermal insulation material; 5. Electromagnetic heating coil; 6. Solenoid valve; 7. Temperature probe; 8. Electromagnetic heater; 9. PLC controller; 10. Coil lead cable. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0029] In the description of the embodiments of the present invention, it should be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invented product is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0030] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components must be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0031] In the description of the embodiments of the present invention, "plurality" means at least 2.

[0032] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] The present invention is described in detail and specifically by specific examples below to provide a better understanding of the present invention, but the following examples do not limit the protection scope of the present invention.

[0034] Example 1

[0035] This embodiment discloses a method for recycling waste agricultural film based on a dual-frequency electromagnetic induction heating process.

[0036] like Figure 1 , Figure 2 As shown, the electromagnetic heating coil model and PLC temperature intelligent control system adopted in this embodiment.

[0037] A barrel 2 is sleeved on the screw 1, plastic 3 is between the screw 1 and the barrel 2, the outer side of the barrel 2 is wrapped with a heat insulating material 4, and an electromagnetic heating ring 5 is arranged on the outer side of the heat insulating material 4.

[0038] Several groups of electromagnetic heating coils 5 are provided on the outside of the thermal insulation material 4, each group of electromagnetic heating coils 5 is electrically connected to the electromagnetic valve 6, a temperature probe 7 is provided in the middle of each group of electromagnetic heating coils 5, the electromagnetic heater 8 is connected to the electromagnetic valve 6 through a coil lead cable 10, and the PLC controller 9 is electrically connected to the electromagnetic valve 6 and the temperature probe 7.

[0039] This embodiment specifically includes the following steps:

[0040] 1) Classification and collection: waste agricultural films are classified and collected according to their materials and thickness. The materials include polyethylene and polyvinyl chloride;

[0041] 2) Pretreatment, which includes cleaning, drying, crushing, magnetic separation, and screening. The cleaning adopts multi-stage cleaning, and the drying needs to control the temperature. The waste agricultural film is crushed by a crusher, the metal impurities are removed by magnetic separation, and the larger particles of impurities are removed by screening. The waste agricultural film is pretreated to obtain agricultural film fragments;

[0042] 3) Dual-frequency electromagnetic induction heating: select appropriate dual-frequency electromagnetic induction heating equipment according to the classification, set the power, frequency range, and temperature control parameters of the equipment, use low and medium frequencies for agricultural films made of polyethylene, and use high frequencies for agricultural films made of polyvinyl chloride. Add agricultural film fragments into the heating chamber of the dual-frequency electromagnetic induction heating equipment, pass high-frequency current into the induction coil at the feeding end, and low-frequency current acts on the induction coil at the discharging end. During the heating process, the PLC temperature intelligent control system monitors the temperature in the barrel in real time to obtain molten material;

[0043] 4) Extrusion granulation, preheating the extruder, sending the molten material to the feeding port of the preheated extruder, the extruder includes a feeding section, a compression section, and a homogenization section, and different sections require different temperatures. The filter at the outlet of the extruder filters impurities and extrude the material through the die of the extruder to form a strip material;

[0044] 5) Cooling and pelletizing: the strip material enters the cooling water tank for cooling. The cooled strip material is cut into granular material by a pelletizer, and the granular material is collected and packaged.

[0045] Electromagnetic coil heating uses the principle of electromagnetic induction to heat the metal barrel itself, and a certain thickness of heat insulation material is wrapped around the outside of the barrel to reduce heat loss and improve thermal efficiency. Because the electromagnetic heating control ring itself does not generate heat, and is made of insulating materials and high-temperature cables, there is no problem of resistance wire oxidation under high temperature conditions like electric heating rings and shortening the service life. It has the advantages of long service life, fast heating rate, no need for maintenance, etc., reducing maintenance time and reducing costs.

[0046] Dual-frequency electromagnetic induction heating solves the temperature control problem by using electromagnetic heating controller. Electromagnetic heating controller is a device that converts electrical energy into thermal energy by using the principle of electromagnetic induction. The electromagnetic controller rectifies 220V, 50 / 60Hz AC into DC, and then converts DC into high-frequency high-voltage electricity with a frequency of 20-40KHz. High-speed changing high-frequency high-voltage current flowing through the coil will produce a high-speed changing alternating magnetic field. When the magnetic lines of force in the magnetic field pass through the magnetic conductive metal material, countless small eddy currents will be generated in the metal body, causing the metal material itself to heat up at a high speed, thereby achieving the purpose of heating the internal materials of the metal material. The electromagnetic heating controller has the remarkable characteristics of significant power saving effect, fast heating speed, high thermal efficiency, lower production environment temperature, and maintenance-free.

[0047] This process uses a PLC temperature intelligent control system, which realizes automatic temperature control and is simple and convenient to operate. The PLC temperature intelligent control system is an automated control system that integrates PLC control technology, temperature instrument technology, and equipment serial communication technology. It is used to achieve real-time monitoring and control of temperature during the production process to ensure product quality and production efficiency. It consists of one or more PLC controllers, temperature sensors, solenoid valves, temperature controllers, etc. Under the control of the PLC controller, the temperature in the production process is monitored in real time through the temperature sensor, and a control signal is sent out according to the set temperature requirements to control the operation of equipment such as solenoid valves and temperature controllers, thereby achieving temperature control.

[0048] The electromagnetic induction heating equipment is set according to the frequency range, with low frequency of 1-5kHz, medium frequency of 10-30kHz, and high frequency of more than 40kHZ. The material and thickness of waste agricultural film have different requirements for the electromagnetic field frequency. For thinner polyethylene agricultural film, lower low frequency (such as 1-5kHz) and appropriate medium frequency (such as 10-30kHz) can meet its needs for rapid heating and uniform heating. For thicker or mixed material agricultural film, a wider frequency range or higher frequency is required to ensure that the heat can penetrate the agricultural film and heat it evenly, thereby achieving an efficient heating and melting process.

[0049] The dual-frequency electromagnetic induction heating equipment has the function of adjusting the frequency combination. For agricultural films made of polyethylene, a lower frequency is used to quickly increase the overall temperature during the initial heating stage, and then the medium frequency is switched to improve the heating efficiency during the plasticizing stage.

[0050] Different frequency combinations have different heating efficiencies. An ideal dual-frequency electromagnetic induction heating device should have the function of adjusting the frequency combination so that it can be optimized according to the actual situation of the agricultural film raw materials. For example, in the initial heating stage, a lower frequency is used to quickly increase the overall temperature, and in the plasticizing stage, a higher medium frequency is switched to make the material more evenly heated, improve heating efficiency, and reduce heating time and energy consumption.

[0051] The temperature of the feeding section is controlled at 120-150°C, the temperature of the compression section is 150-180°C, and the temperature of the homogenization section is 180-220°C.

[0052] C, the temperature control accuracy is controlled at 120-150℃ in the feeding section of the extruder. This section is mainly for preliminary heating and conveying of the material. The lower temperature can soften the material slowly and smoothly enter the screw; the temperature of the compression section is 150-180°C. In this section, the material is compressed by the screw, and the temperature gradually rises, making it further plasticized; the temperature of the homogenization section is 180-220℃, and the material is fully plasticized and mixed evenly in this section.

[0053] The recycling and granulation of waste agricultural film requires high temperature control. Suitable equipment should be able to achieve a temperature control accuracy of less than ±5°C. Accurate temperature control helps ensure that the agricultural film can be processed at the appropriate temperature in different processing stages (such as preheating, plasticization, and extrusion). In the preheating stage, the appropriate temperature can gradually soften the agricultural film to facilitate subsequent melting; in the plasticization stage, accurate temperature control can fully plasticize the agricultural film and improve the quality of the pellets; in the extrusion stage, stable temperature can ensure that the material is smoothly extruded into strips, reduce problems such as unstable pellet performance and color changes caused by temperature fluctuations, and ensure the quality consistency of recycled plastic pellets.

[0054] The dual-frequency electromagnetic induction heating equipment is provided with a screw, and the screw speed is 30-60 revolutions per minute.

[0055] The screw speed will affect the residence time and shearing effect of the material in the screw. If the speed is too low, the material will stay in the screw for too long, which may cause material degradation and affect the quality of the particles; if the speed is too high, the shear force on the material will be too large, which will cause the material temperature to rise too quickly, which may also cause material degradation and increase the energy consumption and wear of the equipment. Therefore, it is necessary to select the appropriate screw speed according to the actual situation to ensure that the material can be fully plasticized in an appropriate time, while reducing material degradation and equipment loss.

[0056] The cleaning process includes preliminary flushing, soaking, and re-rinsing. Use a high-pressure water gun to preliminarily flush the waste agricultural film, soak the agricultural film in a cleaning solution containing an appropriate amount of surfactant, and use a stirring device to allow the cleaning solution to fully contact the agricultural film. The soaking time is controlled at 15-30 minutes, and then use a high-pressure water gun to flush again to ensure that the surface of the agricultural film is clean. The drying temperature is controlled at 60-80℃, and the moisture content of the agricultural film is reduced to 2%-5% after drying. The size of the fragments after crushing is controlled between 5-20mm. This size range is convenient for uniform heating in the dual-frequency electromagnetic induction heating equipment, and will not cause blockage in the subsequent transportation and processing process.

[0057] Generally, it is 60-80℃. If the moisture content in the polyethylene raw material is too high, the moisture will vaporize at high temperature to form bubbles during the subsequent processing. These bubbles will be mixed in the recycled plastic particles, affecting the density, strength and appearance quality of the particles. By controlling the drying temperature at 60-80℃, the moisture in the raw material can be effectively removed to avoid the formation of bubbles.

[0058] Impurities, such as sand, metal shavings, etc., should be removed as much as possible. Magnetic separation is usually used to remove metal impurities. The metal shavings in waste agricultural film are separated by the metal's adsorption characteristics to the magnetic field; larger particles of impurities are screened out, and impurities larger than a certain size are screened out through screens with different apertures. The presence of impurities will affect the purity and performance of recycled plastic particles. For example, it may damage the screw and mold during the extrusion process, reducing product quality, so the degree of impurity removal must be strictly controlled.

[0059] The filter screen is 100-200 mesh, the cooling water temperature is generally 10-30℃, and the diameter of the particle material is 2-5mm.

[0060] The cooling water temperature is generally 10-30℃. The appropriate water temperature can ensure that the polyethylene particles are quickly shaped and have good appearance and dimensional stability. If the water temperature is too high, the particles will cool slowly and easily deform, affecting the shape and dimensional accuracy of the particles; if the water temperature is too low, it may cause stress inside the particles, reducing the strength and toughness of the particles. By controlling the cooling water temperature at 10-30℃, the particles can be quickly cooled and shaped while maintaining good physical properties.

[0061] The filter screen usually uses a 100-200 mesh filter. The filter screen is mainly used to further filter impurities to ensure the purity of the particles. During the extrusion process, when the material passes through the filter screen, the tiny impurities in it will be blocked by the filter screen, making the extruded material purer. If the filter screen mesh is too low, it cannot effectively filter impurities and affect the quality of the particles; if the filter screen mesh is too high, it will increase the extrusion resistance of the material, reduce production efficiency, and may even cause the filter screen to be blocked, affecting the continuity of production. Therefore, choosing a 100-200 mesh filter screen can ensure the purity of the particles while maintaining a high production efficiency.

[0062] Select appropriate dual-frequency electromagnetic induction heating equipment according to the scale of the production line. For a small-scale waste agricultural film recycling and granulation production line with a daily output of 1-2 tons, select equipment with a power of 30-50kW. For a medium-sized production line with a daily output of 3-5 tons, select equipment with a power of 50-100kW. For a large-scale production line with a daily output of more than 5 tons, select equipment with a power of more than 100kW to ensure that the waste agricultural film can be heated and melted in a timely and effective manner to meet production needs.

[0063] The specific embodiments of the present invention are described in detail above, but they are only examples, and the present invention is not equivalent to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, the equalization changes and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention.

Claims

1. A method for recycling waste agricultural film based on dual-frequency electromagnetic induction heating process, characterized in that: The specific steps include: 1) Classification and collection: waste agricultural films are classified and collected according to their materials and thickness. The materials include polyethylene and polyvinyl chloride; 2) Pretreatment, which includes cleaning, drying, crushing, magnetic separation, and screening. The cleaning adopts multi-stage cleaning, and the drying needs to control the temperature. The waste agricultural film is crushed by a crusher, the metal impurities are removed by magnetic separation, and the larger particles of impurities are removed by screening. The waste agricultural film is pretreated to obtain agricultural film fragments; 3) Dual-frequency electromagnetic induction heating: select appropriate dual-frequency electromagnetic induction heating equipment according to the classification, set the power, frequency range, and temperature control parameters of the equipment, use low and medium frequencies for agricultural films made of polyethylene, and use high frequencies for agricultural films made of polyvinyl chloride. Add agricultural film fragments into the heating chamber of the dual-frequency electromagnetic induction heating equipment, pass high-frequency current into the induction coil at the feeding end, and low-frequency current acts on the induction coil at the discharging end. During the heating process, the PLC temperature intelligent control system monitors the temperature in the barrel in real time to obtain molten material; 4) Extrusion granulation, preheating the extruder, sending the molten material to the feeding port of the preheated extruder, the extruder includes a feeding section, a compression section, and a homogenization section, and different sections require different temperatures. The filter at the outlet of the extruder filters impurities and extrude the material through the die of the extruder to form a strip material; 5) Cooling and pelletizing: the strip material enters the cooling water tank for cooling. The cooled strip material is cut into granular material by a pelletizer, and the granular material is collected and packaged.

2. A method for recycling waste agricultural film based on dual-frequency electromagnetic induction heating process according to claim 1, characterized in that: The electromagnetic induction heating equipment is set according to the frequency range, the low frequency is 1-5kHz, the medium frequency is 10-30kHz, and the high frequency is greater than 40kHZ.

3. A method for recycling waste agricultural film based on dual-frequency electromagnetic induction heating process according to claim 2, characterized in that: The dual-frequency electromagnetic induction heating equipment has the function of adjusting the frequency combination. For agricultural films made of polyethylene, a lower frequency is used to quickly increase the overall temperature during the initial heating stage, and then switched to a medium frequency during the plasticizing stage to improve heating efficiency.

4. A method for recycling waste agricultural film based on dual-frequency electromagnetic induction heating process according to claim 1, characterized in that: The temperature of the feeding section of the extruder is controlled at 120-150°C, the temperature of the compression section is 150-180°C, the temperature of the homogenization section is 180-220°C, and the temperature control accuracy is within ±5°C.

5. A method for recycling waste agricultural film based on dual-frequency electromagnetic induction heating process according to claim 1, characterized in that: The dual-frequency electromagnetic induction heating equipment is provided with a screw, and the screw speed is 30-60 revolutions per minute.

6. A method for recycling waste agricultural film based on dual-frequency electromagnetic induction heating process according to claim 1, characterized in that: The cleaning process includes initial flushing, soaking, and re-rinsing. Use a high-pressure water gun to initially flush the waste agricultural film, soak the agricultural film in a cleaning solution containing an appropriate amount of surfactant, and use a stirring device to allow the cleaning solution to fully contact the agricultural film. The soaking time is controlled at 15-30 minutes, and then use a high-pressure water gun to flush again to ensure that the surface of the agricultural film is clean. The drying temperature is controlled at 60-80℃, and the moisture content of the agricultural film is reduced to 2%-5% after drying. The size of the fragments after crushing is controlled between 5-20mm.

7. A method for recycling waste agricultural film based on dual-frequency electromagnetic induction heating process according to claim 1, characterized in that: The filter screen is 100-200 mesh, the cooling water temperature is generally 10-30℃, and the diameter of the particle material is 2-5mm.

8. A method for recycling waste agricultural film based on dual-frequency electromagnetic induction heating process according to claim 1, characterized in that: Choose appropriate dual-frequency electromagnetic induction heating equipment according to the scale of the production line. For a small-scale waste agricultural film recycling and granulation production line with a daily output of 1-2 tons, choose equipment with a power of 30-50kW. For a medium-sized production line with a daily output of 3-5 tons, choose equipment with a power of 50-100kW. For a large-scale production line with a daily output of more than 5 tons, choose equipment with a power of more than 100kW.

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