A method for chemical co-processing and staged pyrolysis of photovoltaic modules

Abstract

This invention belongs to the field of photovoltaic module recycling technology, specifically relating to a method for chemically synergistically staged pyrolysis of photovoltaic modules. The method provided by this invention first heats the photovoltaic module at low temperature to soften the EVA and allow the backsheet to peel off. Then, the module after backsheet removal is immersed in an organic solvent. First, it is immersed in an organic solvent with lower polarity to achieve initial swelling of the EVA, and then immersed in an organic solvent with higher polarity to achieve full swelling of the EVA. Finally, it undergoes high-temperature pyrolysis to obtain separated glass and crystalline silicon solar cells. This method, particularly the use of two organic solvents with different polarities to swell the EVA, effectively separates the photovoltaic module, reduces the breakage rate of the crystalline silicon solar cells, reduces solvent and energy consumption, does not release fluorine-containing gases, and thoroughly treats the EVA.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic module recycling technology, specifically relating to a method for chemically co-processing and staged pyrolysis of photovoltaic modules. Background Technology

[0002] Solar energy, as a safe, stable, and continuous clean and renewable energy source, has recently attracted much attention. Solar photovoltaic (PV) modules are the core component of photovoltaic conversion systems, and with the maturity of production technology and the reduction in costs, PV installation capacity has experienced explosive growth. However, PV modules generally have a lifespan of 20-25 years, so the huge installed capacity will inevitably lead to a huge amount of PV waste in the future. How to efficiently and recycle waste PV modules has become the final step in the construction of PV systems.

[0003] Currently, existing technologies for processing photovoltaic modules include physical and chemical methods. Physical methods include mechanical treatment and thermal treatment, while chemical methods include organic solvent dissolution. Although these methods can separate the backsheet, glass, and crystalline silicon cells, the resulting crystalline silicon cells have a high breakage rate or consume large amounts of organic solvents. They may also leave EVA (ethylene-vinyl acetate copolymer) residues, causing environmental pollution, and the crystalline silicon cells have poor reusability.

[0004] For example, mechanical processing of photovoltaic modules is energy-intensive, cannot recover intact glass and crystalline silicon cells during the process, and may generate fine-grained powder, which is difficult to process. Secondly, EVA in the modules cannot be removed, making subsequent processing cumbersome. Thermal treatment can lead to incomplete EVA removal, leaving residues on the surface of the glass and crystalline silicon cells. Uneven heating during the pyrolysis of silicon cells may also cause them to break and lose their integrity. Furthermore, when processing large volumes of pyrolysis, pyrolysis oil and gas are not easily completely volatilized, remaining on the cell surface and affecting purity. Organic solvent dissolution methods result in excessive consumption of chemical solvents and very slow reaction rates; the large amounts of organic waste generated are difficult to treat, causing serious pollution to the environment and water bodies, hindering large-scale application. Existing technologies also employ combined physical and chemical methods to treat photovoltaic modules, but these do not effectively solve the above problems. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the above-mentioned defects in the photovoltaic module recycling process of the prior art, and thus provide a method for chemical co-processing and segmented pyrolysis of photovoltaic modules.

[0006] Therefore, the present invention provides the following technical solution:

[0007] This invention provides a method for chemically synergistic segmented pyrolysis treatment of photovoltaic modules, comprising the following steps:

[0008] S1, soften the photovoltaic module and peel off the backsheet to obtain the peeled photovoltaic module;

[0009] S2, the stripped photovoltaic module is immersed once in the first organic solvent, and then immersed a second time in the second organic solvent to obtain the swollen photovoltaic module;

[0010] Wherein, the polarity of the second organic solvent is greater than that of the first organic solvent;

[0011] S3 involves pyrolyzing the swollen photovoltaic module to separate the glass from the crystalline silicon solar cells.

[0012] Optionally, the first organic solvent includes at least one of n-hexane, cyclohexane, diethyl ether, and benzene;

[0013] And / or, the second organic solvent includes at least one of ethyl acetate, ethanol, and acetone.

[0014] Optionally, in step S2, the temperature of the first soaking is 30-60℃, and the soaking time is 0.1-0.5h.

[0015] Optionally, in step S2, the temperature of the second soaking is 60-70℃, and the soaking time is 0.1-0.5h.

[0016] Optionally, in step S1, the softening temperature is 100-180℃ and the softening time is 0.1-1h.

[0017] Optionally, in step S1, a softening treatment is performed in an air atmosphere.

[0018] Optionally, in step S3, the pyrolysis temperature is 400-650℃ and the pyrolysis time is 0.5-3h.

[0019] Optionally, in step S3, the pyrolysis step is carried out under a protective atmosphere.

[0020] Optionally, in step S3, the protective atmosphere includes at least one of nitrogen and argon.

[0021] Optionally, before softening, the process may include removing the frame and / or junction box. The specific removal method is standard practice in the field and is not specifically limited here.

[0022] The technical solution of this invention has the following advantages:

[0023] The present invention provides a method for chemically synergistically staged pyrolysis of photovoltaic modules, comprising the following steps: S1, softening the photovoltaic module and peeling off the backsheet to obtain a peeled photovoltaic module; S2, immersing the peeled photovoltaic module once in a first organic solvent and then immersing it a second time in a second organic solvent to obtain a swollen photovoltaic module; wherein the polarity of the second organic solvent is greater than that of the first organic solvent; S3, pyrolyzing the swollen photovoltaic module to separate the glass from the crystalline silicon solar cells. This invention first heats the photovoltaic module at low temperature to soften the EVA and allow the backsheet to be peeled off. Then, the module, after the backsheet is removed, is immersed in an organic solvent. Initial immersion in a low-polarity organic solvent allows for preliminary swelling of the EVA, followed by immersion in a high-polarity organic solvent for full swelling. Finally, high-temperature pyrolysis is performed to obtain separated glass and crystalline silicon solar cells. This method effectively separates the photovoltaic module, reduces the breakage rate of the crystalline silicon solar cells (EVA swelling provides a channel for the rapid release of organic gases generated during subsequent high-temperature pyrolysis, preventing gas accumulation and cell breakage), reduces solvent consumption (low-mass solvent required for immersion) and energy consumption (low temperature for backsheet peeling and pyrolysis for separation of remaining components, requiring similarly low temperatures), does not release fluorine-containing gases (the backsheet is peeled off first at low temperature without subsequent high-temperature heating), completely removes EVA (through organic solvent immersion and pyrolysis), and leaves no residue. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a process flow diagram of the chemical method for co-processing and segmented pyrolysis of photovoltaic modules provided in Embodiment 1 of the present invention. Detailed Implementation

[0026] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0027] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0028] Example 1

[0029] This embodiment provides a method for chemical-assisted segmented pyrolysis treatment of photovoltaic modules, and the process flow diagram is shown below. Figure 1 As shown, it includes the following steps:

[0030] (1) The photovoltaic module containing glass plate / EVA / crystalline silicon cell / EVA / backsheet, after the aluminum frame and junction box have been removed, is placed in a low-temperature pyrolysis furnace and pyrolyzed at 120°C for 1 hour in air atmosphere. The backsheet is then quickly peeled off to obtain the separated module glass plate / EVA / crystalline silicon cell / EVA and the separated backsheet.

[0031] (2) The above separation components were then pretreated by first immersing them in n-hexane at 40°C for 0.2 h, and then immersed in ethyl acetate at 60°C for 0.3 h.

[0032] (3) The pretreated separation components were placed in a high-temperature pyrolysis furnace and pyrolyzed at 500°C for 1 hour under a nitrogen atmosphere. EVA was completely removed (by observing the surface of the glass and crystalline silicon solar cells, it was found that there was basically no residual EVA on the surface, the same below). Finally, the separated backsheet, glass and crystalline silicon solar cells were obtained. The integrity of the crystalline silicon solar cells (integrity = weight of the whole crystalline silicon solar cell obtained after treatment / weight of the crystalline silicon solar cells in the photovoltaic module, where the whole crystalline silicon solar cell obtained after treatment is a whole piece, excluding broken small pieces of solar cells, the same below) was 91%.

[0033] Example 2

[0034] This embodiment provides a method for chemically synergistically staged pyrolysis treatment of photovoltaic modules, including the following steps:

[0035] (1) The photovoltaic module containing glass plate / EVA / crystalline silicon solar cell / EVA / backsheet, after the aluminum frame and junction box have been removed, is placed in a low-temperature pyrolysis furnace and pyrolyzed at 150°C for 0.5h in an air atmosphere. The backsheet is then quickly peeled off to obtain the separated module glass plate / EVA / crystalline silicon solar cell / EVA and the separated backsheet.

[0036] (2) The above separation components were then first soaked in n-hexane for pretreatment at 50°C for 0.3 h, and then soaked in ethyl acetate at 60°C for 0.3 h.

[0037] (3) The pretreated separation components are placed in a high-temperature pyrolysis furnace and pyrolyzed at 500°C for 1 hour under a nitrogen atmosphere. EVA is completely removed, and finally the separated backsheet, glass and crystalline silicon solar cells are obtained. The integrity of the crystalline silicon solar cells is 93%.

[0038] Example 3

[0039] This embodiment provides a method for chemically synergistically staged pyrolysis treatment of photovoltaic modules, including the following steps:

[0040] (1) The photovoltaic module containing glass plate / EVA / crystalline silicon solar cell / EVA / backsheet, after the aluminum frame and junction box have been removed, is placed in a low-temperature pyrolysis furnace and pyrolyzed at 150°C for 0.5h in an air atmosphere. The backsheet is then quickly peeled off to obtain the separated module glass plate / EVA / crystalline silicon solar cell / EVA and the separated backsheet.

[0041] (2) The above separation components were then pretreated by first immersing them in n-hexane at 50°C for 0.5 h, and then immersed in ethyl acetate at 65°C for 0.3 h.

[0042] (3) The pretreated separation components are placed in a high-temperature pyrolysis furnace and pyrolyzed at 550°C for 2 hours under a nitrogen atmosphere. EVA is completely removed, and finally the separated backsheet, glass and crystalline silicon solar cells are obtained. The integrity of the crystalline silicon solar cells is 95%.

[0043] Example 4

[0044] This embodiment provides a method for chemically synergistically staged pyrolysis treatment of photovoltaic modules, including the following steps:

[0045] (1) The photovoltaic module containing glass plate / EVA / crystalline silicon solar cell / EVA / backsheet, after the aluminum frame and junction box have been removed, is placed in a low-temperature pyrolysis furnace and pyrolyzed at 150°C for 0.5h in an air atmosphere. The backsheet is then quickly peeled off to obtain the separated module glass plate / EVA / crystalline silicon solar cell / EVA and the separated backsheet.

[0046] (2) The above separation components were then first soaked in n-hexane for pretreatment at 50°C for 0.3 h, and then soaked in ethyl acetate at 70°C for 0.4 h.

[0047] (3) The pretreated separation components are placed in a high-temperature pyrolysis furnace and pyrolyzed at 600°C for 1 hour under a nitrogen atmosphere. EVA is completely removed, and finally the separated backsheet, glass and crystalline silicon solar cells are obtained. The integrity of the crystalline silicon solar cells is 95%.

[0048] Example 5

[0049] This embodiment provides a method for chemically synergistically staged pyrolysis treatment of photovoltaic modules, including the following steps:

[0050] (1) The photovoltaic module containing glass plate / EVA / crystalline silicon solar cell / EVA / backsheet, after the aluminum frame and junction box have been removed, is placed in a low-temperature pyrolysis furnace and pyrolyzed at 150°C for 0.5h in an air atmosphere. The backsheet is then quickly peeled off to obtain the separated module glass plate / EVA / crystalline silicon solar cell / EVA and the separated backsheet.

[0051] (2) The above separation components were then first soaked in n-hexane for pretreatment at 60°C for 0.4 h, and then soaked in ethyl acetate at 70°C for 0.5 h.

[0052] (3) The pretreated separation components are placed in a high-temperature pyrolysis furnace and pyrolyzed at 550°C for 2 hours under a nitrogen atmosphere. EVA is completely removed, and finally the separated backsheet, glass and crystalline silicon solar cells are obtained. The integrity of the crystalline silicon solar cells is 98%.

[0053] Example 6

[0054] This embodiment provides a method for chemically synergistically staged pyrolysis treatment of photovoltaic modules, including the following steps:

[0055] (1) The photovoltaic module containing glass plate / EVA / crystalline silicon solar cell / EVA / backsheet, after the aluminum frame and junction box have been removed, is placed in a low-temperature pyrolysis furnace and pyrolyzed at 150°C for 0.5h in an air atmosphere. The backsheet is then quickly peeled off to obtain the separated module glass plate / EVA / crystalline silicon solar cell / EVA and the separated backsheet.

[0056] (2) The above separation components were then first soaked in cyclohexane for pretreatment at 60°C for 0.4 h, and then soaked in ethanol at 70°C for 0.5 h.

[0057] (3) The pretreated separation components were placed in a high-temperature pyrolysis furnace and pyrolyzed at 550°C for 2 hours under a nitrogen atmosphere. EVA was completely removed, and finally the separated backsheet, glass and crystalline silicon solar cells were obtained. The integrity of the crystalline silicon solar cells was 98.5%.

[0058] Comparative Example 1

[0059] This comparative example provides a method for processing photovoltaic modules, including the following steps:

[0060] (1) The photovoltaic module containing glass plate / EVA / crystalline silicon cell / EVA / backsheet, after the aluminum frame and junction box have been removed, is placed in a low-temperature pyrolysis furnace and pyrolyzed at 120°C for 1 hour in air atmosphere. The backsheet is then quickly peeled off to obtain the separated module glass plate / EVA / crystalline silicon cell / EVA and the separated backsheet.

[0061] (2) The above separation components were then pretreated by immersing them in n-hexane at 40°C for 0.5 h.

[0062] (3) The pretreated separation components were placed in a high-temperature pyrolysis furnace and pyrolyzed at 500°C for 1 hour under a nitrogen atmosphere. A small amount of EVA remained. Finally, the separated backsheet, glass and crystalline silicon solar cells were obtained. The integrity of the crystalline silicon solar cells was 74%.

[0063] Comparative Example 2

[0064] This comparative example provides a method for processing photovoltaic modules, including the following steps:

[0065] (1) The photovoltaic module containing glass plate / EVA / crystalline silicon cell / EVA / backsheet, after the aluminum frame and junction box have been removed, is placed in a low-temperature pyrolysis furnace and pyrolyzed at 120°C for 1 hour in air atmosphere. The backsheet is then quickly peeled off to obtain the separated module glass plate / EVA / crystalline silicon cell / EVA and the separated backsheet.

[0066] (2) The above separation components were then pretreated by immersing them in ethyl acetate at 60°C for 0.5 h.

[0067] (3) The pretreated separation components were placed in a high-temperature pyrolysis furnace and pyrolyzed at 500°C for 1 hour under a nitrogen atmosphere. A small amount of EVA remained. Finally, the separated backsheet, glass and crystalline silicon solar cells were obtained. The integrity of the crystalline silicon solar cells was 79%.

[0068] Comparative Example 3

[0069] This comparative example provides a method for processing photovoltaic modules, including the following steps:

[0070] (1) The photovoltaic module containing glass plate / EVA / crystalline silicon cell / EVA / backsheet, after the aluminum frame and junction box have been removed, is placed in a low-temperature pyrolysis furnace and pyrolyzed at 120°C for 1 hour in air atmosphere. The backsheet is then quickly peeled off to obtain the separated module glass plate / EVA / crystalline silicon cell / EVA and the separated backsheet.

[0071] (2) The above separation components were then pretreated by first immersing them in ethyl acetate at 40°C for 0.2 h, and then immersed in n-hexane at 60°C for 0.3 h.

[0072] (3) The pretreated separation components were placed in a high-temperature pyrolysis furnace and pyrolyzed at 500°C for 1 hour under a nitrogen atmosphere. A small amount of EVA remained. Finally, the separated backsheet, glass and crystalline silicon solar cells were obtained. The integrity of the crystalline silicon solar cells was 81%.

[0073] Comparative Example 4

[0074] This comparative example provides a method for processing photovoltaic modules, including the following steps:

[0075] (1) The photovoltaic module containing glass plate / EVA / crystalline silicon cell / EVA / backsheet, after the aluminum frame and junction box have been removed, is placed in a low-temperature pyrolysis furnace and pyrolyzed at 120°C for 1 hour in air atmosphere. The backsheet is then quickly peeled off to obtain the separated module glass plate / EVA / crystalline silicon cell / EVA and the separated backsheet.

[0076] (2) The pretreated separation components were placed in a high-temperature pyrolysis furnace and pyrolyzed at 500°C for 1 hour under a nitrogen atmosphere. A small amount of EVA remained. Finally, the separated backsheet, glass and crystalline silicon solar cells were obtained. The integrity of the crystalline silicon solar cells was 65%.

[0077] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method of treating photovoltaic modules by a chemical process in synergy with a fractional pyrolysis, characterized by, The method comprises the following steps: S1, softening the photovoltaic module, peeling off the back plate to obtain a peeled photovoltaic module; S2, immersing the peeled photovoltaic module in a first organic solvent for the first time, and then immersing it in a second organic solvent for the second time to obtain a swollen photovoltaic module; Wherein, the polarity of the second organic solvent is greater than that of the first organic solvent; S3, pyrolyzing the swollen photovoltaic module to separate the glass from the crystalline silicon cell piece; The first organic solvent comprises at least one of n-hexane, cyclohexane, diethyl ether, and benzene; The second organic solvent comprises at least one of ethyl acetate, ethanol, and acetone.

2. The method of chemically synergistic staged pyrolytic treatment of photovoltaic modules of claim 1, wherein, In step S2, the temperature of the first immersion is 30-60℃, and the time of the first immersion is 0.1-0.5h.

3. The method of chemically synergistic decontaminating and fractionating photovoltaic modules by thermal processes according to claim 1, wherein, In step S2, the temperature of the second immersion is 60-70℃, and the time of the second immersion is 0.1-0.5h.

4. The method of chemically synergistic staged pyrolytic treatment of photovoltaic modules according to any of claims 1-3, characterized in that, In step S1, the softening temperature of the softening is 100-180℃, and the softening time of the softening is 0.1-1h.

5. The method of chemically synergistic staged pyrolytic treatment of photovoltaic modules of claim 4, wherein, In step S1, the softening treatment is carried out in an air atmosphere.

6. The method of chemically synergistic staged pyrolytic treatment of photovoltaic modules according to any one of claims 1-3, characterized in that, In step S3, the pyrolysis temperature of the pyrolysis is 400-650℃, and the pyrolysis time of the pyrolysis is 0.5-3h.

7. The method of chemically synergistic decontaminating and fractionating photovoltaic modules by thermal processes according to claim 6, wherein, In step S3, the pyrolysis is carried out in a protective atmosphere.

8. The method of chemically synergistic decontaminating and fractionating photovoltaic modules by thermal processes according to claim 7, wherein, In step S3, the protective atmosphere comprises at least one of nitrogen and argon.

9. The method of chemically synergistic staged pyrolytic treatment of photovoltaic modules according to any of claims 1-3, 5 and 7-8, characterized in that, Before softening, the method further comprises the step of removing the frame and / or the junction box.

10. The method of chemically treating photovoltaic modules by synergistic fractional pyrolysis according to claim 4, wherein, Before softening, the method further comprises the step of removing the frame and / or the junction box.

11. The method of chemically treating photovoltaic modules by synergistic fractional pyrolysis according to claim 6, wherein, Before softening, the method further comprises the step of removing the frame and / or the junction box.

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