Method for efficiently separating photovoltaic module at low temperature based on dry ice refrigerant

Abstract

The invention provides a method for efficiently separating a photovoltaic module at low temperature based on a dry ice refrigerant, which comprises the following steps of: firstly, carrying out primary treatment including disassembly on the photovoltaic module to obtain an integral piece mainly formed by combining glass, a silicon wafer and a back plate, and then cutting the obtained integral piece to obtain a block piece to be separated, and the block-shaped piece to be separated is soaked in a dry ice refrigerant for 30-50 s, the temperature is kept at-45 DEG C to-50 DEG C in the soaking process, and after the time is up, the block-shaped piece to be separated is taken out, and back plate separation is achieved by applying external force. According to the invention, the backplane separation of the photovoltaic module can be realized in an extremely short time by using the dry ice refrigerant, and the separation efficiency is far higher than that of the existing separation means; and a contrast experiment finds that the supersaturated CO2 gas in the dry ice type refrigerant is remarkably beneficial to the separation efficiency and the separation effect of the back plate, a new way is provided for the photovoltaic module on the separation of the back plate, and the method can be used as a foundation for the development of a follow-up technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic module recycling, and in particular relates to a method for low-temperature and high-efficiency separation of photovoltaic modules based on dry ice-type refrigerants. Background Art

[0002] With the rapid growth of the world economy and the rapid increase in population, people's demand for energy is increasing. However, traditional fossil energy has the disadvantages of being non-renewable, having large carbon emissions, and polluting the environment. Excessive use will cause great environmental pressure and it is difficult to meet people's growing energy needs in production and life. Therefore, the development of new energy has gradually become a common goal and consensus of the international community.

[0003] Driven by favorable energy policies and continuous progress in photovoltaic power generation technology, the global cumulative installed capacity of photovoltaic power generation will reach 1,185GW in 2022. But at the same time, the life of photovoltaic modules is usually around 25 years. Therefore, the earliest installed modules are approaching the end of their service life and will generate a large amount of photovoltaic module waste in the future. According to the International Renewable Energy Agency (IRENA), by 2030, the amount of discarded photovoltaic modules will accumulate to 8 million tons, and by 2050, it will accumulate to 78 million tons. According to the China Photovoltaic Industry Association, by around 2030, the country will face the problem of recycling 1.5 million tons of scrapped photovoltaic modules, reaching the first peak of photovoltaic module retirement, and will reach 20 million tons in 2050. (Cheema, HA; Ilyas, S.; Kang, H.; Kim, H., Comprehensive review of the global trends and future perspectives for recycling of decommissioned photovoltaic panels. WASTE MANAGEMENT 2024, 174, 187-202.; Li Lin, Zhang Yingting, Li Long, et al. Research progress on recycling of scrapped crystalline silicon photovoltaic modules[J]. Guangzhou Chemical Industry, 2023, 51(09): 10-12.)

[0004] At present, crystalline silicon (c-Si) photovoltaic modules play a leading role in global photovoltaic modules, accounting for more than 95% of all photovoltaic module types. The first batch of retired crystalline silicon photovoltaic modules can be mainly divided into several parts, such as aluminum alloy frame, glass, EVA sealant, silicon wafer, backplane, junction box, etc. The aluminum alloy frame is used for reinforcement; the glass layer is used for dust prevention and protection of silicon wafers; the EVA sealant is used for interlayer bonding; the backplane is mostly a three-layer structure, in which the fluorine-containing layer is used to resist UV and chemical corrosion, and the PET layer has good mechanical properties and electrical insulation properties, and has certain barrier properties, which can extend the battery life. Most of these materials have high utilization value, so efficient recycling technology is urgently needed. According to the structure and service life of the first batch of photovoltaic modules, there will be a large-scale retirement of photovoltaic modules with fluorine-containing backplanes in recent years. If there is no reasonable and efficient treatment plan for the polymer part, it will cause great pressure on the environment. At present, there are two main recycling methods that can effectively process the polymer part: one is to carry out overall processing, that is, mechanically remove most of the glass, crush and powderize it, and then separate the components; the other is to carry out interlayer separation first, and then use different recycling schemes for different layers. For interlayer separation, the main methods include pyrolysis to remove EVA sealant, chemical solvent swelling, hot knife cutting, etc. In actual separation, some auxiliary means are often used or multiple separation methods are combined to improve the separation efficiency, such as ultrasound-assisted swelling, microwave-assisted swelling, swelling-pyrolysis coupling, etc. Green solvents are also used in the separation process, but the separation efficiency has always been low, and pyrolysis will also produce harmful gases, and there is a lack of green and efficient separation solutions.

[0005] After searching, the Chinese invention patent application "Method for disassembling retired photovoltaic modules based on low-temperature pyrolysis" (CN115488130A) discloses a method for disassembling retired photovoltaic modules based on low-temperature pyrolysis, which includes the following steps: S1. First, the retired photovoltaic modules are dismantled by mechanical separation to obtain aluminum frames and junction boxes; S2. Then, the back panels of the remaining parts of the retired photovoltaic modules are turned upwards, and the surface of the back panels is grinded in a low-temperature environment to separate the back panels from other parts; S3. The remaining parts of the retired photovoltaic modules are placed flat in a heating furnace with the glass panels facing downwards, and the temperature is continuously raised to 500°C and then kept warm. At the same time, nitrogen is introduced into the heating furnace to decompose the EVA packaging material in a high-temperature environment, and the glass panels and solar cells are separated, and then the glass panels can be recycled.

[0006] In the above-mentioned patent technology and prior art, in the step of separating the backboard of photovoltaic modules, there have been very few attempts in recent years to separate them through low-temperature process conditions, which is greener and more environmentally friendly than traditional methods. However, this process step usually requires very low temperatures (such as -196°C in the above-mentioned patent application), or needs to be accompanied by auxiliary means (such as grinding), and under the above conditions, it usually takes several minutes or even dozens of minutes to successfully separate the backboard, which has low recycling efficiency for the large number of retired photovoltaic modules at this stage. Summary of the invention

[0007] In order to solve the above-mentioned problems in the prior art, the present invention provides a method for low-temperature and high-efficiency separation of photovoltaic modules based on dry ice-type refrigerants. By utilizing dry ice-type refrigerants, the backboard of the photovoltaic module can be separated in a very short time, and the separation efficiency is much higher than the existing separation means. Moreover, through comparative experiments, it is found that the supersaturated CO2 gas in the dry ice-type refrigerant is significantly beneficial to the separation efficiency and separation effect of the backboard, which provides a new way for the backboard separation of photovoltaic modules and can serve as the foundation for the subsequent technological development.

[0008] To achieve the above objectives, the present invention is implemented by adopting a technical solution consisting of the following technical measures.

[0009] A method for low-temperature and high-efficiency separation of photovoltaic modules based on dry ice refrigerants mainly comprises the following steps:

[0010] (1) performing preliminary processing including disassembly of the photovoltaic module to obtain an integral component mainly composed of glass, silicon wafer, and backplane;

[0011] (2) cutting the integral piece obtained in step (1) into block pieces to be separated with an outer diameter not greater than 10 cm;

[0012] (3) immersing the block to be separated obtained in step (2) in a dry ice-type refrigerant for 30 to 50 seconds, and maintaining the temperature at -45 to -50°C by adding dry ice during the immersion process. After the time is up, the block to be separated is taken out and the back plate is separated by applying an external force of 10 to 100 N, including any one or more of shear force and tensile force;

[0013] The dry ice refrigerant is a mixed liquid in which dry ice is used as a cold source and mixed with a low melting point solvent.

[0014] In this article, the preliminary treatment of the photovoltaic module including disassembly in step (1) is a conventional preliminary treatment method for photovoltaic modules in the technical field, which is usually mainly to remove the aluminum alloy frame and junction box connected to the photovoltaic module. Conventional equipment recycling and treatment methods such as mechanical disassembly / mechanical separation can be selected, for example, the aluminum alloy frame and junction box are removed by manual disassembly. Those skilled in the art can disassemble the photovoltaic module to obtain an integral part mainly composed of glass, silicon wafers, and backplane according to the actual situation of the photovoltaic module to be separated. If necessary, other non-integral parts need to be processed by simple mechanical disassembly (for example, referring to the disassembly of the aluminum alloy frame) to obtain the integral part described in this article.

[0015] In this article, the integral part described in step (1) is mainly composed of a combination of glass, silicon wafers, and a backplane, and its shape is a multi-layer plate structure. The purpose of the invention is to separate the backplane in the integral part from other layers, so as to obtain the backplane for further processing and recycling.

[0016] In this article, the photovoltaic modules in step (1) are recyclables that need to be separated, recycled and reused, for example, they can be retired / wasted photovoltaic modules, or they can be scraps / defective products in the production process of photovoltaic modules.

[0017] In this article, the whole piece described in step (2) is cut to obtain a block piece to be separated with an outer diameter of no more than 10 cm, the purpose of which is to miniaturize the whole piece to improve the subsequent separation efficiency. The cutting method can directly choose to use conventional equipment recycling and processing methods or conventional cutting methods for plate pieces. It should be noted that the shape of the block piece to be separated obtained by cutting usually does not affect the efficiency of backplane separation using the method of the present invention. Based on the principle of convenient cutting, the following embodiment is to cut the whole piece to obtain a rectangular block piece to be separated with a side length of no more than 10 cm.

[0018] In this article, the dry ice refrigerant in step (3) is a mixed liquid blended with a low melting point solvent using dry ice as a cold source, wherein the low melting point solvent should satisfy the requirement that the temperature of the liquid state reaches -45 to -50°C after adding dry ice for blending. It should be noted that the low temperature solvent method using dry ice as a cold source is a conventional process for low temperature baths in the chemical industry. Those skilled in the art can select a suitable low melting point solvent, especially a solvent having a melting point not higher than -50°C, based on the temperature parameters (-45 to -50°C) provided by the present invention. However, generally speaking, in order to ensure the overall environmental protection and greenness of the separation method of the present invention, the low melting point solvent is preferably a non-toxic / low-toxic low melting point solvent.

[0019] In order to better illustrate the present invention and provide a technical solution for reference, the low melting point solvent in step (3) is selected from any one of anhydrous ethanol, isopropanol, acetone, and ethyl acetate.

[0020] In one of the preferred technical solutions, in order to further improve the separation efficiency, the separation block in step (3) is immersed in a dry ice-type refrigerant, and the volume ratio of the material to the liquid is not higher than 1 / 2.

[0021] In this article, after taking out the block to be separated in step (3), the back plate is separated by applying an external force of 10 to 100 N including shear force and tensile force or any one or more thereof. It should be noted that under laboratory conditions, it has been tested that when the block to be separated is fixed at one end and a 1 kg weight is placed at the other end, the back plate can be separated by slightly bending the block due to the gravity of the weight. Therefore, when separating the block on an industrial scale, the separation can be achieved by applying any one or more external forces including shear force and tensile force, for example, by using vacuum suction cups on both sides of the block to separate the block.

[0022] The present invention is based on the accidental discovery by the inventor when using liquid nitrogen to perform low-temperature quenching treatment on photovoltaic modules that the low-temperature environment provided by liquid media such as liquid nitrogen can significantly more effectively and quickly separate the backplane. Inspired by this and taking cost factors into consideration, in an exploratory experiment trying to use a low-temperature solvent method with dry ice as a cold source for immersion treatment, it was surprisingly found that although the low-temperature environment temperature was increased from -196°C of liquid nitrogen to -45 to -50°C, the separation efficiency and separation effect were further significantly improved. When the immersion time was 30 to 50 seconds, the backplane could be separated by simply applying external force.

[0023] After further comparative tests, by comparing the separation after immersion at the same low temperature using a non-dry ice refrigerant, based on the judgment of the time required for immersion and the completeness of separation, it was found that dry ice refrigerants were significantly more effective for backplane separation. It is speculated that this may be because the CO2 gas generated by dry ice as a cold source is concentrated and released at the block to be separated, and the CO2 in the solvent is always in a supersaturated state during the entire separation process (solid dry ice always exists in the system). When a low melting point solvent (such as anhydrous ethanol) diffuses into the photovoltaic module, the CO2 therein also continuously dissipates between the layers at any time, plays an expansion role, and improves the separation efficiency and separation effect of the backplane. Therefore, the present invention provides a new way for photovoltaic modules to separate backplanes, and can serve as a foundation for subsequent technical development.

[0024] It should be noted that, based on the cutting shape and size of the block to be separated, it was found through experiments that the block to be separated with a smaller cutting side length (square, 3 cm side length) has a more efficient backplane separation efficiency than the block to be separated with a larger cutting side length (square, 10 cm side length). The immersion time is still excellent when it is less than 30s. The backplane separated from the block to be separated with a smaller side length is also smaller, which is not convenient for separating the backplane under external force, and may not be conducive to the subsequent recycling of the backplane. Based on this, in one of the preferred technical solutions, the integral part obtained in step (1) is cut in step (2) to obtain a block to be separated with an outer diameter of 5 to 10 cm.

[0025] The present invention has the following beneficial effects:

[0026] 1. The present invention provides a method for separating photovoltaic modules at low temperature and high efficiency based on dry ice refrigerants. By utilizing dry ice refrigerants, the back panels of photovoltaic modules can be separated in a very short time, and the separation efficiency is much higher than that of existing separation methods.

[0027] 2. The dry ice refrigerant used in the present invention is green and environmentally friendly. Usually, no toxic gas, liquid, etc. are produced during the entire separation process. It is operator-friendly. The dry ice refrigerant used therein is reusable, and only dry ice is consumed to maintain the temperature, which is suitable for large-scale industrial applications.

[0028] 3. Through comparative experiments, the present invention found that the supersaturated CO2 gas in the dry ice refrigerant is significantly beneficial to the separation efficiency and separation effect of the backplane, providing a new way for the backplane separation of photovoltaic modules and can serve as the foundation for subsequent technological development. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a photo showing the actual object after the back plate is separated in Example 1 of the present invention.

[0030] Figure 2 This is a side-view photograph of the block to be separated before impregnation in Example 1 of the present invention.

[0031] Figure 3 This is a photo showing the actual object after the back plate is separated in Example 2 of the present invention.

[0032] Figure 4 This is a photo showing the actual object after the back plate is separated in Example 3 of the present invention.

[0033] Figure 5 This is a photo showing the actual object after the back plate is separated in Example 4 of the present invention.

[0034] Figure 6 This is a photo showing the actual object after the back plate is separated in Comparative Example 1 of the present invention.

[0035] Figure 7 The following are photos showing the physical objects after the backplane separation in Example 1 and Comparative Example 2 of the present invention. The left side shows the backplane separation effect of the separation method of Example 1, and the right side shows the backplane separation effect of the separation method of Comparative Example 2.

[0036] Figure 8 This is a photo showing the actual object after the back panel separation failed in comparative example 3 of the present invention.

[0037] Fig. 9 This is a photo of the dipping process in Example 1 of the present invention. DETAILED DESCRIPTION

[0038] In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It is particularly important to point out that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can obviously change or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention. Although it is believed that those of ordinary skill in the art fully understand the following terms, the following definitions are still stated to help illustrate the subject matter disclosed by the present invention.

[0039] A method for low-temperature and high-efficiency separation of photovoltaic modules based on dry ice refrigerants mainly comprises the following steps:

[0040] (1) performing preliminary processing including disassembly of the photovoltaic module to obtain an integral component mainly composed of glass, silicon wafer, and backplane;

[0041] (2) cutting the integral piece obtained in step (1) into block pieces to be separated with an outer diameter not greater than 10 cm;

[0042] (3) immersing the block to be separated obtained in step (2) in a dry ice-type refrigerant for 30 to 50 seconds, and maintaining the temperature at -45 to -50°C by adding dry ice during the immersion process. After the time is up, the block to be separated is taken out and the back plate is separated by applying an external force of 10 to 100 N, including any one or more of shear force and tensile force;

[0043] The dry ice refrigerant is a mixed liquid in which dry ice is used as a cold source and mixed with a low melting point solvent.

[0044] In this article, the preliminary treatment of the photovoltaic module including disassembly in step (1) is a conventional preliminary treatment method for photovoltaic modules in the technical field, which is usually mainly to remove the aluminum alloy frame and junction box connected to the photovoltaic module. Conventional equipment recycling and treatment methods such as mechanical disassembly / mechanical separation can be selected, for example, the aluminum alloy frame and junction box are removed by manual disassembly. Those skilled in the art can disassemble the photovoltaic module to obtain an integral part mainly composed of glass, silicon wafers, and backplane according to the actual situation of the photovoltaic module to be separated. If necessary, other non-integral parts need to be processed by simple mechanical disassembly (for example, referring to the disassembly of the aluminum alloy frame) to obtain the integral part described in this article.

[0045] In this article, the integral part described in step (1) is mainly composed of a combination of glass, silicon wafers, and a backplane, and its shape is a multi-layer plate structure. The purpose of the invention is to separate the backplane in the integral part from other layers, so as to obtain the backplane for further processing and recycling.

[0046] In this article, the photovoltaic modules in step (1) are recyclables that need to be separated, recycled and reused, for example, they can be retired / wasted photovoltaic modules, or they can be scraps / defective products in the production process of photovoltaic modules.

[0047] In this article, the whole piece described in step (2) is cut to obtain a block piece to be separated with an outer diameter of no more than 10 cm, the purpose of which is to miniaturize the whole piece to improve the subsequent separation efficiency. The cutting method can directly choose to use conventional equipment recycling and processing methods or conventional cutting methods for plate pieces. It should be noted that the shape of the block piece to be separated obtained by cutting usually does not affect the efficiency of backplane separation using the method of the present invention. Based on the principle of convenient cutting, the following embodiment is to cut the whole piece to obtain a rectangular block piece to be separated with a side length of no more than 10 cm.

[0048] In this article, the dry ice refrigerant in step (3) is a mixed liquid blended with a low melting point solvent using dry ice as a cold source, wherein the low melting point solvent should satisfy the requirement that the temperature of the liquid state reaches -45 to -50°C after adding dry ice for blending. It should be noted that the low temperature solvent method using dry ice as a cold source is a conventional process for low temperature baths in the chemical industry. Those skilled in the art can select a suitable low melting point solvent, especially a solvent having a melting point not higher than -50°C, based on the temperature parameters (-45 to -50°C) provided by the present invention. However, generally speaking, in order to ensure the overall environmental protection and greenness of the separation method of the present invention, the low melting point solvent is preferably a non-toxic / low-toxic low melting point solvent.

[0049] In order to better illustrate the present invention and provide an implementation method for reference, the low melting point solvent in step (3) is selected from any one of anhydrous ethanol, isopropanol, acetone, and ethyl acetate.

[0050] In one preferred embodiment, in order to further improve the separation efficiency, the separation block in step (3) is immersed in a dry ice-type refrigerant, and the volume ratio of the material to the liquid is not higher than 1 / 2.

[0051] In this article, after taking out the block to be separated in step (3), the back plate is separated by applying an external force of 10 to 100 N including shear force and tensile force or any one or more thereof. It should be noted that under laboratory conditions, it has been tested that when the block to be separated is fixed at one end and a 1 kg weight is placed at the other end, the back plate can be separated by slightly bending the block due to the gravity of the weight. Therefore, when separating the block on an industrial scale, the separation can be achieved by applying any one or more external forces including shear force and tensile force, for example, by using vacuum suction cups on both sides of the block to separate the block.

[0052] The present invention is based on the accidental discovery by the inventor when using liquid nitrogen to perform low-temperature quenching treatment on photovoltaic modules that the low-temperature environment provided by liquid media such as liquid nitrogen can significantly more effectively and quickly separate the backplane. Inspired by this and taking cost factors into consideration, in an exploratory experiment trying to use a low-temperature solvent method with dry ice as a cold source for immersion treatment, it was surprisingly found that although the low-temperature environment temperature was increased from -196°C of liquid nitrogen to -45 to -50°C, the separation efficiency and separation effect were further significantly improved. When the immersion time was 30 to 50 seconds, the backplane could be separated by simply applying external force.

[0053] After further comparative tests, by comparing the separation after immersion at the same low temperature using a non-dry ice refrigerant, based on the judgment of the time required for immersion and the completeness of separation, it was found that dry ice refrigerants were significantly more effective for backplane separation. It is speculated that this may be because the CO2 gas generated by dry ice as a cold source is concentrated and released at the block to be separated, and the CO2 in the solvent is always in a supersaturated state during the entire separation process (solid dry ice always exists in the system). When a low melting point solvent (such as anhydrous ethanol) diffuses into the photovoltaic module, the CO2 therein also continuously dissipates between the layers at any time, plays an expansion role, and improves the separation efficiency and separation effect of the backplane. Therefore, the present invention provides a new way for photovoltaic modules to separate backplanes, and can serve as a foundation for subsequent technical development.

[0054] It should be noted that, based on the cutting shape and size of the block to be separated, it was found through experiments that the block to be separated with a smaller cutting side length (square, 3 cm side length) has a more efficient backplane separation efficiency than the block to be separated with a larger cutting side length (square, 10 cm side length). The immersion time is still excellent when it is less than 30s. The backplane separated from the block to be separated with a smaller side length is also smaller, which is not convenient for separating the backplane under external force, and may not be conducive to the subsequent recycling of the backplane. Based on this, in one of the preferred technical solutions, the integral part obtained in step (1) is cut in step (2) to obtain a block to be separated with an outer diameter of 5 to 10 cm.

[0055] The present invention will be further explained in detail with reference to the following examples. However, it should be understood by those skilled in the art that these examples are provided for illustrative purposes only and are not intended to limit the present invention.

[0056] Example

[0057] The embodiments of the present application will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. The specific conditions not specified in the examples are carried out according to the conditions recommended by normal conditions or manufacturers. The reagents used or the instruments not specified by the manufacturer are all conventional products that can be obtained commercially. The application should not be construed as being limited to the specific examples described.

[0058] 1. Raw materials

[0059] Decommissioned PV panels purchased from the second-hand market;

[0060] Anhydrous ethanol (CH3CH2OH), Shanghai Fine Chemical Reagent Co., Ltd.;

[0061] Solid dry ice, Chengdu Dingsheng Times Technology Co., Ltd.

[0062] 2. Preparation method

[0063] (1) Performing preliminary processing including disassembly of retired photovoltaic modules, removing aluminum alloy frames and junction boxes by manual disassembly, and obtaining an integral component mainly composed of glass, silicon wafers, and backplanes;

[0064] (2) cutting the integral piece obtained in step (1) into square blocks to be separated with a side length of no more than 10 cm;

[0065] (3) Immerse the block to be separated obtained in step (2) in a dry ice-type refrigerant for 30 to 50 seconds, and keep the temperature at -45 to -50°C by adding dry ice during the immersion process. After the time is up, take out the block to be separated and apply an external force of about 10N shear force manually (hold the edge of the block to be separated with the index finger and press the middle part with the thumb to apply force) to produce a slight bending deformation to achieve back plate separation;

[0066] The dry ice refrigerant is a mixture of dry ice as a cold source and anhydrous ethanol.

[0067] Example 1

[0068] Example 1 is in accordance with the above-mentioned "2. Preparation method" steps, in step (2) a square block with a side length of 3 cm is cut to be separated, in step (3) the immersion time is 30 seconds, and after taking out, the back plate is separated under the action of external force.

[0069] like Figure 1 As shown in the figure, the backplane was separated relatively well, with only a very small amount of silicon wafer remaining.

[0070] like Figure 2 As shown, the side view photo of the block to be separated before dipping shows that the backplane is tightly bonded to the silicon wafer.

[0071] like Fig. 9 As shown, when the block pieces to be separated are impregnated, CO2 gas is concentrated at the block pieces to be separated and released.

[0072] Example 2

[0073] Example 2 is in accordance with the above-mentioned "2. Preparation method" steps, in step (2) a square block with a side length of 5 cm is cut to be separated, in step (3) the immersion time is 30 seconds, and after taking out, the back panel is separated under the action of external force.

[0074] like Figure 3 As shown in the figure, the backplane has been separated relatively well, but some silicon wafers and more metal still remain.

[0075] Example 3

[0076] Example 3 follows the above-mentioned "2. Preparation method" steps, and in step (2) a square block with a side length of 5 cm is cut to be separated. In step (3), the immersion time is 40 seconds, and after taking out, the back panel is separated under the action of external force.

[0077] like Figure 4 As shown, the backplane has achieved relatively complete separation, and compared with Example 2, it can be seen that the metal residue is significantly reduced, but silicon wafer residues still exist.

[0078] Example 4

[0079] Example 4 is in accordance with the above-mentioned "2. Preparation method" steps, in step (2) a square block with a side length of 5 cm is cut to be separated, in step (3) the immersion time is 50 seconds, and after taking out, the back panel is separated under the action of external force.

[0080] like Figure 5 As shown, compared with Example 2, the backplane separation effect is further improved, the metal residue is reduced and there is no silicon wafer residue.

[0081] Comparative Example 1

[0082] Comparative Example 1 follows the above-mentioned "2. Preparation method" steps, in step (2) a square block to be separated with a side length of 5 cm is cut, in step (3) the immersion time is 20 seconds, and after taking out, the back panel is separated under the action of external force.

[0083] like Figure 6 As shown, it is difficult to achieve complete separation due to the short immersion time, and about a quarter of the backing plate remains.

[0084] Comparative Example 2

[0085] Comparative Example 2 refers to the above-mentioned "2. Preparation method" step. In step (2), a square block to be separated with a side length of 3 cm is cut, but in step (3), the dry ice / anhydrous ethanol system is replaced with pure anhydrous ethanol at the same temperature. The immersion time is 45 seconds. After taking out, the back panel is separated under the action of external force.

[0086] For a more intuitive comparison, the temperature during the immersion process was manually controlled and maintained at about -46°C. For comparison, the temperature during the immersion process was also manually controlled based on the conditions of Example 1 and maintained at about -46°C.

[0087] like Figure 7 As shown, the separation effect of Example 1 is significantly better than that of Comparative Example 2, and the immersion time of Example 1 is significantly shorter.

[0088] Comparative Example 3

[0089] Comparative Example 3 refers to the above-mentioned "2. Preparation method" step. In step (2), a square block to be separated with a side length of 3 cm is cut. However, in step (3), the dry ice / anhydrous ethanol system is replaced with pure anhydrous ethanol at the same temperature. The immersion time is 30 seconds. The temperature is manually controlled during the immersion process and maintained at about -47°C. After taking out, the back panel cannot be separated under the action of external force.

[0090] like Figure 8 As shown, comparative example 3 cannot separate the back plate under the action of external force.

[0091] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for separating photovoltaic modules at low temperature and high efficiency based on dry ice refrigerants, characterized in that The main steps include: (1) performing preliminary processing including disassembly of the photovoltaic module to obtain an integral component mainly composed of glass, silicon wafer, and backplane; (2) cutting the integral piece obtained in step (1) into block pieces to be separated with an outer diameter not greater than 10 cm; (3) immersing the block to be separated obtained in step (2) in a dry ice-type refrigerant for 30 to 50 seconds, and maintaining the temperature at -45 to -50°C by adding dry ice during the immersion process. After the time is up, the block to be separated is taken out and the back plate is separated by applying an external force of 10 to 100 N, including any one or more of shear force and tensile force; The dry ice refrigerant is a mixed liquid in which dry ice is used as a cold source and mixed with a low melting point solvent.

2. The method according to claim 1, characterized in that: The photovoltaic modules described in step (1) are recyclable materials that need to be separated, recycled and reused, including retired / wasted photovoltaic modules and scraps / defective products in the production process.

3. The method according to claim 1, characterized in that: The low melting point solvent in step (3) includes any one of anhydrous ethanol, isopropanol, acetone, and ethyl acetate.

4. The method according to claim 1, characterized in that: The separated block pieces in step (3) are immersed in a dry ice-type refrigerant, and the volume ratio of the material to the liquid is not higher than 1 / 2.

5. The method according to claim 1, characterized in that: The block to be separated in step (3) is immersed in a dry ice-like refrigerant for 30 to 40 seconds.

6. The method according to claim 1, characterized in that: In step (2), the integral piece obtained in step (1) is cut into block pieces to be separated with an outer diameter of 5 to 10 cm.

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