Method for separating glass and back plate in waste photovoltaic module by green solvent hydrothermal method

Abstract

The invention belongs to the technical field of photovoltaic module recovery, and particularly relates to a method for separating glass and a back plate in a waste photovoltaic module through a green solvent hydrothermal method. The method comprises the following steps: 1) cutting a waste crystalline silicon photovoltaic module, and removing an aluminum frame and a junction box to obtain a small photovoltaic module without the aluminum frame and the junction box; 2) washing the photovoltaic module obtained in the step 1) with an absolute ethyl alcohol solution; and 3) placing the photovoltaic module obtained in the step 2) in an inner container of a reaction kettle, pouring an ethyl lactate solvent, carrying out a heating reaction at 90-140 DEG C for 0.80-1.2 h, separating the glass layer from the front EVA layer of the crystalline silicon photovoltaic module, and separating the backboard layer from the back EVA layer of the crystalline silicon photovoltaic module. Based on the green solvent ethyl lactate, the tempered glass and the fluorine-containing backboard are effectively separated through a mild treatment process, and recycling of the tempered glass and the fluorine-containing backboard is achieved.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic module recycling technology, specifically relating to a green solvent hydrothermal method for separating glass and backsheet from waste photovoltaic modules. Background Technology

[0002] As the photovoltaic industry enters its equipment replacement cycle, the large-scale disposal of retired modules has become an urgent industry issue. Retired modules contain numerous high-value resources such as silicon, silver, and aluminum; efficient recycling can not only achieve resource reuse but also reduce damage to the ecological environment.

[0003] Current mainstream recycling technology systems face multiple bottlenecks: traditional mechanical processing can achieve component dissociation, but it is difficult to overcome the technical barriers to material purification; thermal treatment processes are fundamentally in conflict with the concept of green development due to high energy consumption and pollution emissions; chemical recycling pathways can improve recycling efficiency, but are constrained by challenges in process safety and environmental compatibility.

[0004] Existing physical, mechanical, and pyrolysis methods have not overcome the contradictions between process maturity and material purity, large-scale processing and secondary pollution control, and equipment investment and operating costs. This not only hinders resource recycling but may also create new environmental governance challenges. There is an urgent need to build a low-carbon, efficient, closed-loop recycling system through process innovation and interdisciplinary technology integration to support the sustainable development of the new energy industry. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a green solvent hydrothermal method for separating glass and backsheet from waste crystalline silicon photovoltaic modules. Based on ethyl lactate, a green solvent, this invention effectively separates tempered glass and fluorinated backsheets through a gentle treatment process, enabling the recycling of both. The use of ethyl lactate not only reduces processing costs but also significantly mitigates the environmental burden. The entire process is simple to operate, highly efficient, and produces no harmful gas emissions, making it extremely environmentally friendly. Compared to traditional methods, the ethyl lactate green solvent method demonstrates significant advantages in environmental friendliness, processing efficiency, and cost-effectiveness.

[0006] The technical solution provided by this invention is as follows: A green solvent hydrothermal method for separating glass and backsheet in waste photovoltaic modules includes the following steps: 1) Cut the waste crystalline silicon photovoltaic modules, remove the aluminum frame and junction box, and obtain small photovoltaic modules with the aluminum frame and junction box removed; 2) Wash the photovoltaic modules obtained in step 1) with anhydrous ethanol solution; 3) Place the photovoltaic module obtained in step 2) into the inner liner of the reactor, pour in ethyl lactate solvent, and heat at 90-140°C for 0.80-1.2 hours to separate the glass layer from the front EVA layer of the crystalline silicon photovoltaic module and separate the backsheet layer from the back EVA layer of the crystalline silicon photovoltaic module.

[0007] In the above technical solution, ethyl lactate solvent is used, and heating at a relatively low temperature achieves the following effects: The glass layer and backsheet layer can be separated, while the front EVA-silicon solar cell-back EVA structure is completely preserved, which facilitates further separation of the EVA layer to obtain the solar cell; The chemical immersion process does not corrode or swell EVA, thus avoiding damage to the solar cell; Neither physical disassembly nor chemical soaking steps will corrode the silver grid lines.

[0008] Preferred: In step 3), ethyl lactate solvent is poured into the crystalline silicon photovoltaic module to immerse it.

[0009] Preferably, in step 3), the reaction is carried out at 120°C.

[0010] Preferably, in step 3), the reaction is heated for 1 hour.

[0011] Furthermore, it also includes step 4): recovering the ethyl lactate solvent after the reaction.

[0012] The remaining ethyl lactate solvent after the reaction can be directly recycled and reused, reducing costs.

[0013] Further: Proceed to steps 1) through 4), wherein if the amount of recycled ethyl lactate solvent is insufficient, the original ethyl lactate solvent is added to make up the difference.

[0014] Based on the above technical solution, ethyl lactate solvent can be fully utilized.

[0015] Specifically: In step 3), after separating the glass layer and the backsheet layer, the crystalline silicon photovoltaic module includes a complete front EVA layer, a silicon-based solar cell structure, and a back EVA layer.

[0016] Specifically: In step 3), after separating the glass layer and the backsheet layer, the crystalline silicon photovoltaic module includes a front EVA layer, a silicon-based solar cell structure, and a back EVA layer that are fixedly connected in sequence.

[0017] Specifically: the reactor is heated in a water bath or oven.

[0018] Specifically, the pressure inside the reactor vessel is no higher than 3 MPa.

[0019] Furthermore, after step 3), the backsheet layer is separated into two fluorine-containing layers and one PET layer, that is, each layer in the three-layer backsheet layer is completely separated.

[0020] The beneficial effects of this invention are: 1) All chemical solvents used in this invention are green and pollution-free solvents; 2) The chemical solvents used in this invention can be repeatedly recycled, which greatly reduces the cost of use and the cost of recycling. 3) Compared with the prior art, the advantages of the present invention are that most of the existing methods for separating fluorine-containing backsheets are physical methods, using blades or the like to peel the backsheet from the cell-backsheet interface. Because the adhesion between the interfaces is strong, it is easy to leave residues on the EVA surface on the back side, which reduces the enrichment of fluorine elements and is not conducive to further processing. For example, when pyrolyzing the remaining components, toxic gases such as hydrogen fluoride will still be generated, which will cause some pollution to the environment. However, the technical solution of the present invention does not have this problem. 4) This method uses a wet process to separate the tempered glass and fluorine-containing backsheet in photovoltaic modules. It has a good separation effect on the fluorine-containing backsheet, which not only avoids the residue caused by mechanical methods, but also effectively enriches key elements. Moreover, the remaining modules are easy to recycle and reuse, making it highly practical. Attached Figure Description

[0021] Figure 1 This is a structural diagram of a photovoltaic module.

[0022] Figure 2 This is a diagram of the glass, backsheet, and remaining components of photovoltaic panel a after separation in Example 1.

[0023] Figure 3 This is a separation diagram of the remaining components and the three fluorine-containing thin film layers of photovoltaic panel b after separation in Example 1.

[0024] Figure 4 This is a separation diagram of the remaining components and the three fluorine-containing thin film layers of photovoltaic panel c after separation in Example 1. Detailed Implementation

[0025] The principles and features of the present invention are described below. The embodiments given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0026] Unless otherwise specified, the test methods used in the embodiments are conventional methods; unless otherwise specified, the materials and reagents used are commercially available.

[0027] The concentration of ethyl lactate solvent was analytical grade.

[0028] Example 1 A green solvent hydrothermal method for separating glass and backsheet from waste crystalline silicon photovoltaic modules includes the following steps: 1) Cut photovoltaic panel a, the structure can be referenced. Figure 1 .

[0029] Remove the aluminum frame and junction box from the retired photovoltaic panels, place the remaining photovoltaic panels in an open space, and slowly cut several 2×2cm modules using an angle grinder.

[0030] 2) Preparation of ethyl lactate solvent separation glass and backplate ① Place the 2×2cm component processed in step 1) into the PTFE inner liner.

[0031] ② Pour 25 mL of ethyl lactate solvent into the inner liner.

[0032] ③Place the inner liner after ② into a hydrothermal reactor with a pressure of less than 3MPa.

[0033] ④ Preferably, the hydrothermal reactor is placed in an oven and kept at 120°C for 1 hour.

[0034] ⑤ Remove the hydrothermal reactor after the reaction in step ④, open the tetrafluoroethylene inner liner, and use tweezers to remove the glass and back plate.

[0035] ⑥ The components removed by tweezers in step ⑤ are the three-layer film of glass and back plate (two layers of fluorinated film and PET film), the remaining ethyl lactate solvent liquid in the inner liner and the remaining components.

[0036] In addition, the above steps were repeated using photovoltaic panels b and c from other companies.

[0037] Figure 1 This is a structural diagram of a photovoltaic module.

[0038] Figure 2 This is a diagram of the glass, backsheet, and remaining components of photovoltaic panel a after separation in Example 1, wherein from left to right are glass, remaining components, an example layer of the two fluorine-containing films, and PET film.

[0039] Figure 3 This is a separation diagram of the remaining components of photovoltaic panel b and the three fluorine-containing film layers after separation in Example 1. It can be seen that the three fluorine-containing film layers are completely separated.

[0040] Figure 4 This is a separation diagram of the remaining components of photovoltaic panel c and the three fluorine-containing film layers after separation in Example 1. It can be seen that the three fluorine-containing film layers are completely separated.

[0041] pass Figure 2 , 3As can be seen from point 4, the present invention can separate the glass and the back sheet from the photovoltaic panel, and at the same time, completely separate the back sheet into two layers of fluorine-containing film and PET film.

[0042] Example 2 Referring to Example 1, the difference is that anhydrous ethanol was used to separate each EVA layer. The results showed that although the backsheet layer could be separated, the glass layer could not be separated.

[0043] Example 3 Referring to Example 1, the difference is that triethyl citrate was used for separation. The results showed that although the glass layer and the backsheet layer could be separated, the backsheet layer could not be further separated into three layers, and the time required was significantly increased. At the same time, the EVA film swelled slightly.

[0044] Example 4 Referring to Example 1, the difference is that in step ④, the reaction is carried out in a water bath at 90°C and an oven at 140°C to separate the glass and the backsheet from the photovoltaic panel. At the same time, the backsheet is completely separated into two layers of fluorine-containing film and PET film.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A green solvent hydrothermal method for separating glass and backsheet in waste photovoltaic modules, characterized in that, Includes the following steps: 1) Cut the waste crystalline silicon photovoltaic modules, remove the aluminum frame and junction box, and obtain small pieces of crystalline silicon photovoltaic modules with the aluminum frame and junction box removed; 2) Wash the crystalline silicon photovoltaic module obtained in step 1) with anhydrous ethanol solution; 3) Place the crystalline silicon photovoltaic module obtained in step 2) into the inner liner of the reactor, pour in ethyl lactate solvent, and heat at 90-140°C for 0.80-1.2 hours to separate the glass layer from the front EVA layer of the crystalline silicon photovoltaic module and separate the backsheet layer from the back EVA layer of the crystalline silicon photovoltaic module.

2. The method for separating glass and backsheet in waste photovoltaic modules using a green solvent hydrothermal method according to claim 1, characterized in that: In step 3), ethyl lactate solvent is poured into the crystalline silicon photovoltaic module to immerse it.

3. The method for separating glass and backsheet in waste photovoltaic modules using a green solvent hydrothermal method according to claim 1, characterized in that: In step 3), the reaction is heated at 120°C.

4. The method for separating glass and backsheet in waste photovoltaic modules using a green solvent hydrothermal method according to claim 1, characterized in that: In step 3), the reaction is heated for 1 hour.

5. The method for separating glass and backsheet in waste photovoltaic modules using a green solvent hydrothermal method according to claim 1, characterized in that, It also includes step 4): recovering the ethyl lactate solvent after the reaction.

6. The method for separating glass and backsheet in waste photovoltaic modules using a green solvent hydrothermal method according to claim 5, characterized in that: If the amount of recovered ethyl lactate solvent is insufficient, the original ethyl lactate solvent is added to make up the difference.

7. The method for separating glass and backsheet in waste photovoltaic modules using a green solvent hydrothermal method according to claim 1, characterized in that: In step 3), after separating the glass layer and the backsheet layer, the crystalline silicon photovoltaic module includes a complete front EVA layer, a silicon-based solar cell structure, and a back EVA layer.

8. The method for separating glass and backsheet in waste photovoltaic modules using a green solvent hydrothermal method according to claim 1, characterized in that: In step 3), after separating the glass layer and the backsheet layer, the crystalline silicon photovoltaic module includes a front EVA layer, a silicon-based solar cell structure, and a back EVA layer that are fixedly connected in sequence.

9. The method for separating glass and backsheet in waste photovoltaic modules using a green solvent hydrothermal method according to claim 1, characterized in that: The reactor is heated in a water bath or oven; The pressure inside the reactor vessel shall not exceed 3 MPa.

10. The method for separating glass and backsheet from waste photovoltaic modules using a green solvent hydrothermal method according to any one of claims 1 to 9, characterized in that: In step 3), the backsheet layer is separated into two fluorine-containing layers and one PET layer.

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