Pyrolysis recovery method and device for waste photovoltaic module

Abstract

The invention relates to the technical field of solid waste recycling, in particular to a pyrolysis recycling method and device for a waste photovoltaic module. The device comprises a preheating unit (10), a pore-forming unit (20), a pyrolysis unit (30), a heat preservation unit (40), a pyrolysis gas treatment unit (50) and a superheated steam supply unit (60), the preheating unit (10) is provided with a heating mechanism or is communicated with an external heat source, steam nozzle groups are distributed at the top and / or the bottom of the pore-forming unit (20), the pyrolysis unit (30) is provided with a heating mechanism, the heat preservation unit (40) is provided with a temperature adjusting mechanism, the pyrolysis gas treatment unit (50) is used for performing harmless treatment on pyrolysis gas, and the superheated steam supply unit (60) is used for producing superheated steam. And superheated steam is provided for the pore-forming unit (20). The probability of breakage of the glass plate layer and the crystalline silicon battery piece layer can be reduced, and cyclic utilization of the glass plate layer and the crystalline silicon battery piece layer is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste resource utilization, and specifically to a pyrolysis recovery method and device for waste photovoltaic modules. Background Art

[0002] As a renewable energy source, solar energy has the advantages of being safe, reliable, clean and harmless. The photovoltaic solar power generation industry, which mainly uses solar power generation, has been increasingly valued by the industry. Photovoltaic solar power generation is mainly completed by photovoltaic modules. The service life of photovoltaic modules is generally 20 - 30 years. With the rapid development of the photovoltaic power generation market, the scale of waste photovoltaic modules will also increase rapidly. Therefore, how to handle waste photovoltaic modules, especially how to completely recycle and utilize related components, has become a research topic that has attracted much attention in the industry, and various forms of exploration have been carried out in the existing technology.

[0003] One technical development direction is the pure mechanical separation technology enhanced by a medium. For example, Chinese patent document CN110918601A discloses a steam - jet thermal knife for finely separating the glass in a crystalline silicon solar cell panel from other components, so as to realize the secondary utilization of the glass. The specific technical means are as follows: during the separation process, a high - frequency electromagnetic induction coil is combined to heat the thermal knife, and the temperature of the thermal knife is controlled at about 130°C ± 5°C. At the same time, steam is jetted at the tool head part to fill the interface between the glass plate and the EVA film with water vapor, so as to promote the separation of the glass plate and the EVA adhesive film. In this solution, water vapor is used as a green lubricant to replace oily lubricating substances, which can reduce the wear of the tool and improve the tool life. The disadvantages of this solution are: (1) high requirements for the accuracy of the equipment, and the tool head of the thermal knife needs to accurately cut into the EVA film layer between the glass plate and the silicon crystal plate; (2) relatively high requirements for the flatness of the raw materials of the solar cell panel; (3) there is still EVA residue on the recycled glass, and subsequent processes are required for treatment.

[0004] Another technical development direction is the co-processing technology of organic solvents and high-temperature pyrolysis. Chinese Patent Document CN110624936A discloses a method for disassembling waste photovoltaic modules to achieve the integrity recovery of silicon wafers, including the following steps: (1) Mechanical pre-disassembly: Remove the aluminum frame and junction box through mechanical disassembly to obtain a photovoltaic substrate without the aluminum frame and junction box; (2) Mixed solvent heat treatment: Clamp the photovoltaic substrate with a fixture, place it in a sealed container, add a small amount of organic solvent and pressure aid, and heat to vaporize the organic solvent and pressure aid to perform steam-like restricted swelling on the EVA; After cooling, the EVA in the obtained photovoltaic substrate is in a loose and dispersed state, and the backsheet can be completely peeled off or partially peeled off; (3) High-temperature decomposition heat treatment: Place the photovoltaic substrate with EVA in a loose and dispersed state in a pyrolysis reactor, and decompose the remaining EVA and backsheet through high-temperature pyrolysis, thereby achieving the complete separation of tempered glass and crystalline silicon wafers and the integrity recovery of crystalline silicon wafers. The disadvantages of this solution are: (1) The preferred swelling treatment time is 2-3 hours. Although the time required is much shorter than that of the solvent immersion method, compared with other methods, the time spent is still relatively long; (2) Although the EVA is restricted in swelling, the strength of the crystalline silicon wafer is insufficient and it is still easily crushed. (3) Organic solvents such as benzene, toluene, and ortho-dichlorobenzene are used, which are highly toxic and volatile.

[0005] The third technical development direction is the optimization of the pyrolysis process steps. Chinese Patent Document CN115351052A discloses a resource recovery system for retired photovoltaic modules, including a first recovery component, a second recovery component, a third recovery component, and a fourth recovery component for sequentially recovering the frame, TPT backsheet, battery cells, and tempered glass. The first recovery component heats the photovoltaic module at a high temperature through a first heating device to eliminate the viscosity of the glue between the frame and the photovoltaic module, so as to remove the frame by a manipulator and send it to the frame recovery device for recovery. The second recovery component heats the photovoltaic module through a heating plate to eliminate the viscosity of the glue between the TPT backsheet and the photovoltaic module, and then uses a cutting plate to cut and separate the TPT backsheet and the photovoltaic module as a whole, and then it is recovered by the TPT backlight recovery device. The third recovery component heats the photovoltaic module through a second heating device to eliminate the viscosity of the glue between the battery cells and the photovoltaic module, so as to facilitate the separation of the battery cells from the photovoltaic module, and recover them through the battery cell recovery device. This solution controls the temperature to gradually eliminate the viscosity of silicone and EVA glue, and recovers relatively complete components such as battery cells, tempered glass, TPT backsheets, and aluminum alloy frames, avoiding the problem of component breakage.

[0006] The pyrolysis device disclosed in Chinese Patent Document CN 213968270 U is another pyrolysis optimization mode. Its pyrolysis furnace includes an introduction preparation chamber, a furnace main body, and a discharge preparation chamber. It uses superheated steam as a heat source to heat the photovoltaic module. The introduction preparation chamber, the furnace main body, and the discharge preparation chamber are respectively provided with a superheated steam introduction pipe, a gas outlet pipe, and an in-furnace conveying part. The end of the superheated steam introduction pipe is provided with an upper nozzle for spraying superheated steam downward and a lower nozzle for spraying superheated steam upward. The upper nozzle and the lower nozzle are configured in the pyrolysis furnace to sandwich the panel, so that the plastic material layer is gasified and removed. The disadvantage of this solution is that when using superheated steam as a heat source, a large amount of organic wastewater will be generated after the superheated steam and the pyrolysis products are cooled, and this organic wastewater is difficult to treat. Summary of the Invention

[0007] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a pyrolysis recovery method for waste photovoltaic modules, which can reduce the probability of the glass plate breaking during the heat treatment process and realize the rapid separation of the complete glass plate layer and the crystalline silicon cell layer.

[0008] To achieve the above purpose, the technical solution of the present invention is as follows: A pyrolysis recovery method for waste photovoltaic modules includes the following steps. S1. Frame disassembly: Remove the frame of the waste photovoltaic module in advance to expose the edges of each structural layer of the waste photovoltaic module. S2. Component preheating: Convey the waste photovoltaic module to a preheating space, and the whole waste photovoltaic module is heated to above 80°C. S3. Backsheet hole formation: Convey the waste photovoltaic module to a hole formation space, and use superheated steam to impact the backsheet layer of the waste photovoltaic module, so that the backsheet is thermally decomposed to form holes in the backsheet, thereby establishing a gas release channel for the EVA layer in contact with the backsheet and providing a local swelling space for the EVA layer in contact with the glass plate. S4. Component pyrolysis: Convey the waste photovoltaic module to a pyrolysis space, and the pyrolysis space is heated by an external heat source so that the temperature in the pyrolysis space is maintained at 400 - 800°C. Superheated steam is introduced into the pyrolysis space as a heating medium. The backsheet layer and the EVA layer are thermally decomposed under the dual action of the external heat source and the superheated steam, and the pyrolysis gas is exported for harmless treatment. S5. Heat preservation and cooling: Keep the pyrolysis solid product in a heat preservation space for heat preservation and cooling, and then place it in the environment to cool to room temperature to obtain a photovoltaic cell and a glass plate that are separated from each other.

[0009] The inventive concept of this application lies in: (1) Before and after formal pyrolysis, set a temperature buffer step to enable the waste photovoltaic module to have an intermediate temperature transition during the heating and cooling stages, preventing the glass plate and the crystalline silicon cell from cracking due to rapid heating or rapid cooling.

[0010] (2)Before the formal pyrolysis, a backsheet hole-forming step is also set. Superheated steam is used to impact the backsheet layer of the waste photovoltaic module, causing holes to form instantaneously on the backsheet, thereby establishing a gas release channel for the EVA layer in contact with the backsheet, which is beneficial to the rapid pyrolysis of the EVA layer. Secondly, the holes also provide a local swelling space for the EVA layer in contact with the glass plate. When the EVA layer swells and pushes upward, the holes also provide a certain upward buffer space for the crystalline silicon cell, thereby reducing the probability of the crystalline silicon cell breaking.

[0011] (3)After the module is preheated, the backsheet layer and the EVA layer are softened to a certain extent. When using superheated steam to impact the backsheet, it is beneficial to disperse the impact force and reduce the probability of the crystalline silicon cell breaking.

[0012] (4)Since the specific heat and heat transfer coefficient of superheated steam are larger than those of air, during the formal pyrolysis, superheated steam is used as the heating medium. It should be emphasized that in Chinese patent document CN 213968270 U, superheated steam is used as the heat source, while in this application, the heat source is provided by other external heat sources, and superheated steam is only used as the heat transfer medium to promote the separation of the glass plate layer and the crystalline silicon cell layer. Therefore, the amount of organic wastewater generated in this application is relatively small.

[0013] (5)Superheated steam is a kind of dry saturated steam. After heat exchange and cooling, it forms partial wet saturated steam on the surface of the waste photovoltaic module, which is beneficial to reducing the probability of the glass plate layer and the crystalline silicon cell layer breaking.

[0014] Secondly, it should be pointed out that in Chinese patent document CN 213968270 U, although superheated steam is also sprayed towards the waste photovoltaic module, superheated steam is only used as the heat source for pyrolysis, intending to perform one-time pyrolysis on the waste photovoltaic module, and its purpose is not to form holes in the backsheet.

[0015] As an improvement, in the step S2, the temperature in the preheating space is maintained at 100 - 200 °C, and the preheating time is 5 - 15 min. The preheating time should not be too long to prevent obvious swelling of the EVA.

[0016] As an improvement, the temperature in the preheating space is maintained at 100 - 150 °C, and the preheating time is 5 - 10 min. The preheating temperature should not be too high either.

[0017] As an improvement, in the step S3, the backsheet layer of the waste photovoltaic module is placed upward on the platform, and several superheated steam nozzles are used to wash the backsheet layer from top to bottom. The advantage of this scheme is that the backsheet layer is open and unobstructed, which is beneficial to the rapid decomposition and hole formation of the backsheet.

[0018] As an improvement, in step S3, the back plate layer of the discarded photovoltaic modules is placed on a platform with the back plate facing downward, and a plurality of superheated steam nozzles are used to flush the back plate layer from bottom to top. The advantage of this solution is that there is no obstacle above the discarded photovoltaic modules, and after the discarded photovoltaic modules are impacted by the superheated steam, the discarded photovoltaic modules can be buffered upward, which is conducive to reducing the damage caused by the impact force to the crystalline silicon cell layer.

[0019] As an improvement, in step S3, the hole diameter is a circular hole of not less than 5 mm or a strip hole of not less than 5 mm in width. The larger the hole diameter, the smoother the gas passage, but the amount of superheated steam used will increase.

[0020] As an improvement, in step S3, the flushing time of the backplane layer with superheated steam lasts for 5-15 seconds. As the flushing time increases, holes are formed in the EVA layer in contact with the backplane layer, which can further provide a buffer space for the swelling of the EVA layer. However, when the crystalline silicon cell layer is exposed, it is not advisable to flush the crystalline silicon cell layer directly with high-flow superheated steam, otherwise the probability of the crystalline silicon cell layer breaking will also increase accordingly.

[0021] As an improvement, in step S4, the temperature in the pyrolysis space is maintained at 500-700° C., and the residence time is 30-60 min.

[0022] As an improvement, in step S4, the gas in the pore forming space is introduced into the pyrolysis space to obtain superheated steam as a heating medium.

[0023] As an improvement, in step S4, the superheated steam in the pyrolysis space is stirred to promote the circulation of the stirred superheated steam in the pyrolysis space. Since the amount of superheated steam is small, the circulation is conducive to its medium function, so as to increase the probability of its contact with the EVA layer.

[0024] As an improvement, in step S5, the temperature in the heat preservation space is maintained at 200-300°C, and the residence time of the pyrolysis product in the sealed space is 10-30 min.

[0025] As an improvement, the preheating space and the pyrolysis space are heated by a jacket, and the high-temperature flue gas heats the pyrolysis space and the preheating space in turn; a temperature dilution port is set at the jacket inlet of the preheating space, and air is mixed as needed to adjust the temperature of the high-temperature flue gas to the temperature required for preheating.

[0026] The present application also provides a processing device matching the above method, comprising: The preheating unit is a sealable chamber equipped with a heating mechanism or connected to an external heat source; The hole forming unit is a sealable chamber with a steam nozzle group distributed on the top and / or bottom and a first pyrolysis gas outlet pipe; The pyrolysis unit is an airtight chamber equipped with a heating mechanism, connected to the first pyrolysis gas outlet pipe, and provided with a second pyrolysis gas outlet pipe; The heat preservation unit is an airtight chamber equipped with a temperature regulation mechanism; The pyrolysis gas treatment unit is used for harmless treatment of pyrolysis gas; The superheated steam supply unit is used for producing superheated steam and supplying superheated steam to the pore-forming unit; The preheating unit, pore-forming unit, pyrolysis unit, and heat preservation unit are all provided with inlet and outlet channels to facilitate the entry and exit of waste photovoltaic modules.

[0027] As an improvement, the preheating unit, pore-forming unit, pyrolysis unit, and heat preservation unit are provided with independent conveying platforms, and the conveying platforms are connected in sequence to realize the sequential transfer of waste photovoltaic modules.

[0028] As an improvement, the steam nozzle group is composed of a plurality of steam nozzles arranged in combination.

[0029] As an improvement, a stirring fan is arranged on the side wall of the pyrolysis unit to promote the gas flow in the pyrolysis unit.

[0030] As an improvement, the heating mechanism is a heating jacket. The pyrolysis gas treatment unit includes a combustion chamber. The pyrolysis gas is burned in the combustion chamber to achieve harmless treatment, and the high-temperature flue gas generated by the combustion chamber is used to provide heat for the heating mechanisms of the pyrolysis unit and the preheating unit; it also includes a flue gas tail gas treatment unit.

[0031] As an improvement, the flue gas tail gas treatment unit includes a heat exchanger, and a cooling water collector is arranged below the heat exchanger; the temperature regulation mechanism of the heat preservation unit includes a temperature regulation air supply pipeline, and the external air and the flue gas tail gas are heat-exchanged in the heat exchanger and then transported to the temperature regulation air supply pipeline.

[0032] As an improvement, the heating mechanism is a heating rod, and the heating rods are horizontally arranged in the preheating unit and the pyrolysis unit.

[0033] The beneficial effects of the present invention are: short treatment time, and the whole set of processes is generally completed in 60 - 90 minutes; less generation of organic wastewater; low probability of rupture of the glass plate layer and the crystalline silicon cell layer, which is beneficial to the recycling of the glass plate layer and the crystalline silicon cell layer, and can improve the recycling value and economy of waste photovoltaic modules. Description of the Drawings

[0034] Figure 1 It is a schematic diagram of the structural composition of a photovoltaic module; Figure 2 It is a schematic diagram of the hole structure on the backplane layer of the present invention; Figure 3 It is a layout diagram of the device of the present invention; Figure 4 Schematic diagram of the pore-forming unit in Embodiment 3 of the present invention; Figure 5 Schematic diagram of part of the crawler of the conveying platform in Embodiment 3 of the present invention; Figure 6 Another layout diagram of the device of the present invention; Figure 7 Schematic diagram of the distribution of waste photovoltaic modules in the pore-forming unit in Embodiment 4 of the present invention.

[0035] In the figure: 10, preheating unit; 11, preheating flue gas jacket; 20, pore-forming unit; 30, pyrolysis unit; 31, pyrolysis flue gas jacket; 32, second pyrolysis gas outlet pipe; 33, agitation fan; 34, heating rod; 40, heat preservation unit; 41, temperature adjustment air supply pipeline; 42, temperature adjustment tail gas outlet pipe; 50, pyrolysis gas treatment unit; 51 flue gas and tail gas treatment unit; 511, heat exchanger; 512, cooling water collector; 513, external discharge pipeline; 60, superheated steam supply unit; 61, booster pump; 62, steam nozzle; 63, first pyrolysis gas outlet pipe; 64, steam pipeline; 70, conveying platform; 71, steam channel; 80, waste photovoltaic module; 81, glass plate layer; 82, crystalline silicon cell layer; 83, EVA layer; 84, backplane layer; 841, hole; 85, frame; 90, inlet and outlet channel; 91, electric control door. Embodiment

[0036] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application. Embodiment

[0037] As described in the background art, how to completely recycle waste photovoltaic modules has become a research topic that has attracted much attention in the industry. As Figure 1 shown, a photovoltaic module is usually composed of a glass plate layer 81, an EVA layer 83, a crystalline silicon cell layer 82, an EVA layer 83, and a backplane layer 84 from top to bottom. After each layer is pressed together, a frame 85 is buckled outside. The technical problem that this application focuses on is to ensure that the two EVA layers 83 are quickly and effectively removed while reducing the probability of the glass plate layer 81 and the crystalline silicon cell layer 82 from cracking.

[0038] A pyrolysis recycling method for waste photovoltaic modules provided by this application specifically includes the following steps. S1. Frame disassembly: The frame and junction box of the waste photovoltaic module are removed in advance, so that the edges of the structural layers of the waste photovoltaic module are exposed, and a pretreated photovoltaic module is obtained.

[0039] S2. Component preheating: Convey the waste photovoltaic module to the preheating space. The temperature in the preheating space is maintained at 100 - 200 °C, and the preheating time is 5 - 15 min. The entire waste photovoltaic module needs to be heated to above 80 °C. Preferably, the temperature in the preheating space can be maintained at 100 - 150 °C, the preheating time is 5 - 10 min, and the entire waste photovoltaic module needs to be heated to 100 - 120 °C.

[0040] S3. Backsheet hole formation: Convey the waste photovoltaic module to the hole - forming space, and impact the backsheet layer of the waste photovoltaic module with superheated steam. The scouring time of the superheated steam on the backsheet layer lasts for 5 - 15 s, causing the backsheet to be decomposed by heat in a scattered - point manner and form holes on the backsheet. The diameter of the holes is a circular hole not less than 5 mm, preferably 10 - 20 mm. The holes formed by the impact of superheated steam can also be strip - shaped holes with a width not less than 5 mm, specifically as Figure 2 shown. In the figure, 841 represents the holes formed on the backsheet layer 84. Obviously, if the EVA layer in contact with the backsheet layer also forms holes, the gas channels of the EVA layer will be more unobstructed, and it can further provide a buffer space for the swelling phenomenon of the EVA layer.

[0041] The positional relationship between the waste photovoltaic module and the superheated steam nozzle is as follows: The backsheet layer of the waste photovoltaic module is placed face - up on the platform, and several superheated steam nozzles scour the backsheet layer from top to bottom. As an option, the backsheet layer of the waste photovoltaic module is placed face - down on the platform, and several superheated steam nozzles scour the backsheet layer from bottom to top.

[0042] Generally, superheated steam needs to go through a pressurization step to make its injection speed reach more than 30 m / s, and the injection speed is preferably controlled at 40 - 50 m / s to form sufficient impact force on the backsheet layer.

[0043] S4. Component pyrolysis: Convey the waste photovoltaic module to the pyrolysis space, introduce the gas in the hole - forming space into the pyrolysis space, and no additional superheated steam is introduced into the pyrolysis space. Stir the superheated steam in the pyrolysis space to promote the circulation of the superheated steam in the pyrolysis space. The pyrolysis space is heated by an external heat source so that the temperature in the pyrolysis space is maintained at 400 - 800 °C, preferably 500 - 700 °C, and the residence time is 30 - 60 min.

[0044] The backsheet layer and the EVA layer are decomposed by heat under the dual action of the external heat source and superheated steam, and the pyrolysis gas is exported for harmless treatment.

[0045] The preheating space and the pyrolysis space adopt a jacket heating method. High - temperature flue gas heats the pyrolysis space and the preheating space in sequence; a temperature dilution port is set at the jacket inlet of the preheating space, and air is mixed as needed to adjust the temperature of the high - temperature flue gas to the required temperature for preheating. This is prior art and will not be elaborated further.

[0046] Secondly, obviously, clean superheated steam can also be introduced into the pyrolysis space without being introduced from the pore-forming space. On the premise that superheated steam can also be introduced from the pore-forming space, partial superheated steam can be introduced.

[0047] S5. Heat preservation and cooling: Keep the pyrolyzed solid product in the heat preservation space for heat preservation and cooling. The temperature in the heat preservation space is maintained at 200 - 300 °C, and the residence time of the pyrolysis product in the sealed space is 10 - 30 min. Then it is placed in the environment and cooled to room temperature to obtain the mutually separated photovoltaic cell and glass plate.

[0048] Effect verification: 1. Regarding the processing speed The preheating time of the processed photovoltaic module after removing the frame is 10 min at 120 °C, and it is sent into the pore-forming space. Superheated steam at about 500 °C is continuously introduced into the pore-forming space, and the flow rate of the superheated steam is controlled at about 5 m / s. The generated pyrolysis gas is led to the pyrolysis space. It takes about 60 min for the backsheet layer and the EVA layer to be completely decomposed in the pyrolysis space.

[0049] Adopting the solution described in this application, the preheating time of the processed photovoltaic module after removing the frame is 10 min at 120 °C, and it is sent into the pore-forming space. Superheated steam at the same temperature is sprayed on the backsheet layer at a flow rate of 40 m / s, and several holes are instantly formed in the backsheet layer; then it is transferred to the pyrolysis space. In the heating space at about 500 °C, the backsheet layer and the EVA layer are completely decomposed in about 40 min. Moreover, the superheated steam injection in this application only takes a few seconds. Compared with the comparative method, the usage amount of superheated steam can be ignored, and the subsequent generated amount of organic wastewater can also be ignored.

[0050] 2. Regarding the integrity rate of the glass plate layer and the crystalline silicon cell layer Through experiments, the integrity rate of the obtained glass plate layer and the crystalline silicon cell layer is greater than 90%. The calculation method of the integrity rate is: the number of unbroken photovoltaic modules after processing / the total number of photovoltaic modules. Embodiment

[0051] Embodiment 2 provides a pyrolysis recovery device that can implement the solution described in this application, as Figure 3As shown in the figure, it successively includes a preheating unit 10, a hole-forming unit 20, a pyrolysis unit 30, and a heat preservation unit 40. A pyrolysis gas treatment unit 50 and an overheated steam supply unit 60 are also provided. Among them, the preheating unit 10, the hole-forming unit 20, the pyrolysis unit 30, and the heat preservation unit 40 are all independent sealable chambers, and an access passage 90 is provided to facilitate the entry and exit of the waste photovoltaic module 80 between the chambers. Each access passage 90 is equipped with an electrically controlled door 91. Independent conveying platforms 70 are arranged in the preheating unit 10, the hole-forming unit 20, the pyrolysis unit 30, and the heat preservation unit 40, and the conveying platforms 70 are successively connected to realize the successive transfer of the waste photovoltaic module 80.

[0052] A preheating flue gas jacket 11 is arranged on the outer wall of the preheating unit 10, and a pyrolysis flue gas jacket 31 is arranged on the outer wall of the pyrolysis unit 30. The pyrolysis flue gas jacket 31 is communicated with the preheating flue gas jacket 11 through a pipeline to realize sequential heating.

[0053] Steam nozzle groups are distributed at the top of the hole-forming unit 20. The steam nozzle groups are formed by arranging steam nozzles 62. The steam nozzles 62 are arranged as required so that the steam nozzle groups can form holes in the backsheet layer 84 as Figure 2 shown in the figure. The hole-forming unit 20 is provided with a first pyrolysis gas outlet pipe 63 for guiding the pyrolysis gas and overheated steam in the hole-forming unit 20 to the pyrolysis unit 30. A second pyrolysis gas outlet pipe 32 is also arranged on the pyrolysis unit 30 for guiding the pyrolysis gas in the pyrolysis unit 30 out. To promote the flow of overheated steam in the pyrolysis unit 30, a stirring fan 33 is arranged on the side wall of the pyrolysis unit 30.

[0054] The heat preservation unit 40 is located at the rear end of the pyrolysis unit 30 and is equipped with a temperature regulating mechanism. The temperature regulating mechanism can adopt an air-cooling mode or a water-cooling mode. If the air-cooling mode is adopted, cold air can be introduced into the interior of the heat preservation unit 40; if the water-cooling mode is adopted, a water-cooling jacket is arranged on the outer wall of the heat preservation unit 40. This is the prior art and will not be elaborated here.

[0055] The pyrolysis recovery device further includes a pyrolysis gas treatment unit 50, an overheated steam supply unit 60, and a flue gas and tail gas treatment unit 51. The pyrolysis gas treatment unit 50 is used for harmlessly treating the pyrolysis gas. The main body is a harmless combustion chamber, which uses natural gas as fuel to burn the pyrolysis gas, and the high-temperature flue gas generated by the combustion is introduced into the pyrolysis flue gas jacket 31. The overheated steam supply unit 60 is used for producing overheated steam and providing overheated steam for the hole-forming unit 20. The overheated steam supply unit 60 transports the overheated steam to the steam nozzle groups through a steam pipeline 64. The layout form of the steam pipeline 64 in the hole-forming unit 20 can refer to the Chinese patent document CN 213968270 U. A booster pump 61 is arranged on the pipeline of the overheated steam supply unit 60 to ensure that the overheated steam ejected by the steam nozzles 62 is sufficient to form holes 841 in the backsheet layer 84 within a few seconds.

[0056] The flue gas and tail gas treatment unit 51 includes a heat exchanger 511. A cooling water collector 512 is provided below the heat exchanger 511. After being treated by the heat exchanger 511, the flue gas and tail gas are discharged up to standard via the exhaust pipeline 513, or are discharged up to standard after further treatment. The temperature adjustment mechanism of the heat preservation unit 40 includes a temperature adjustment air supply pipeline 41. The external air and the flue gas and tail gas are heat-exchanged by the heat exchanger 511 and then transported to the temperature adjustment air supply pipeline 41 for cooling the heat preservation unit 40. The heat preservation unit 40 is also provided with a temperature adjustment tail gas discharge pipe 42, and the temperature adjustment tail gas discharge pipe 42 is communicated with the exhaust pipeline 513. For the specific method of air mixing and cooling, reference can be made to the technical solution disclosed in Chinese patent document CN 110961432 A. Obviously, in addition to mixing air for cooling, water cooling can also be used, and for details, reference can be made to the cooling system disclosed in Chinese patent document CN 213968270 U. Embodiment

[0057] The difference between Embodiment 3 and Embodiment 2 is that: as Figure 4 shown, steam spray nozzles 62 are arranged both above and below the hole forming unit 20. The waste photovoltaic module 80 can be placed on the conveying platform 70 with the back plate layer 84 facing up, or can be placed on the conveying platform 70 with the back plate layer 84 facing down. Obviously, although steam spray nozzles 62 are arranged both above and below the hole forming unit 20, the orientation of the waste photovoltaic module 80 when entering the device still needs to be unified, and only the upper or lower steam spray nozzle 62 is used during use.

[0058] As Figure 5 shown, the conveying platform 70 adopts a chain plate type platform, and steam channels 71 are arranged at intervals in the middle position of the conveying platform 70, so that the steam spray nozzles 62 at the bottom can spray the waste photovoltaic module 80 on the conveying platform 70. Embodiment

[0059] The difference between Embodiment 4 and Embodiment 2 is that: another pyrolysis recovery device capable of implementing the solution described in this application is provided.

[0060] As Figure 6 shown, the preheating unit 10 and the pyrolysis unit 30 no longer adopt the high-temperature flue gas jacket heating method, but instead use heating rods 34 for heating. The high-temperature flue gas generated by the pyrolysis gas treatment unit 50 can provide heat source for the superheated steam supply unit 60.

[0061] The superheated steam in the pyrolysis unit 30 still enters from the hole forming unit 20 through the first pyrolysis gas discharge pipe 63. Obviously, the pyrolysis unit 30 does not exclude setting an independent superheated steam inlet pipeline in the pyrolysis unit 30.

[0062] As Figure 7 shown, to improve the processing efficiency, the width of the conveying platform 70 can meet the requirement of arranging 4 waste photovoltaic modules 80 horizontally.

Claims

1. Pyrolysis recovery method for waste photovoltaic modules, Characterized in that: It includes the following steps, S1. Frame disassembly: Remove the frame of the waste photovoltaic module in advance to expose the edges of each structural layer of the waste photovoltaic module; S2. Module preheating: Convey the waste photovoltaic module to the preheating space, and the whole waste photovoltaic module is heated to above 80°C; S3. Backsheet perforation: Convey the waste photovoltaic module to the perforation space, and impact the backsheet layer of the waste photovoltaic module with superheated steam, so that the backsheet is thermally decomposed to form holes in the backsheet, thereby establishing a gas release channel for the EVA layer in contact with the backsheet, and at the same time providing a local swelling space for the EVA layer in contact with the glass plate; S4. Module pyrolysis: Convey the waste photovoltaic module to the pyrolysis space, and the pyrolysis space is heated by an external heat source so that the temperature in the pyrolysis space is maintained at 400 - 800°C. Superheated steam is introduced into the pyrolysis space as a heating medium. The backsheet layer and the EVA layer are thermally decomposed under the dual action of the external heat source and superheated steam, and the pyrolysis gas is exported for harmless treatment; S5. Heat preservation and cooling: Keep the pyrolysis solid product in the heat preservation space for heat preservation and cooling, and then place it in the environment to cool to room temperature to obtain the separated photovoltaic cells and glass plates.

2. The pyrolysis recovery method for waste photovoltaic modules according to claim 1, Characterized in that: In the step S2, the temperature in the preheating space is maintained at 100 - 200°C, and the preheating time is 5 - 15 min.

3. The pyrolysis recovery method for waste photovoltaic modules according to claim 2, Characterized in that: The temperature in the preheating space is maintained at 100 - 150°C, and the preheating time is 5 - 10 min.

4. The pyrolysis recovery method for waste photovoltaic modules according to claim 1, Characterized in that: In the step S3, the backsheet layer of the waste photovoltaic module is placed upward on the platform, and several superheated steam nozzles are used to wash the backsheet layer from top to bottom.

5. The pyrolysis recovery method for waste photovoltaic modules according to claim 1, Characterized in that: In the step S3, the backsheet layer of the waste photovoltaic module is placed downward on the platform, and several superheated steam nozzles are used to wash the backsheet layer from bottom to top.

6. The pyrolysis recovery method for waste photovoltaic modules according to claim 1, Characterized in that: In the step S3, the diameter of the hole is a circular hole not less than 5 mm or a strip-shaped hole with a width not less than 5 mm.

7. The pyrolysis recovery method for waste photovoltaic modules according to claim 1, Characterized in that: In the step S3, the flushing time of the superheated steam on the backsheet layer lasts for 5 - 15 s.

8. The pyrolysis recovery method for waste photovoltaic modules according to claim 1, Characterized in that: In the step S4, the temperature in the pyrolysis space is maintained at 500 - 700°C, and the residence time is 30 - 60 min.

9. The pyrolysis recovery method for waste photovoltaic modules according to claim 1, Characterized in that: In the step S4, the gas in the perforation space is introduced into the pyrolysis space to obtain superheated steam as a heating medium.

10. The pyrolysis recovery method for waste photovoltaic modules according to claim 1, Characterized in that: In step S4, the superheated steam in the pyrolysis space is agitated to promote the circulation of the agitated superheated steam in the pyrolysis space.

11. The pyrolysis recovery method for waste photovoltaic modules according to claim 1, characterized in that: in step S5, the temperature in the heat preservation space is maintained at 200 - 300 °C, and the residence time of the pyrolysis products in the sealed space is 10 - 30 min.

12. The pyrolysis recovery method for waste photovoltaic modules according to claim 1, characterized in that: the preheating space and the pyrolysis space adopt a jacket heating method, and the high-temperature flue gas heats the pyrolysis space and the preheating space in sequence; a temperature dilution port is arranged at the jacket inlet of the preheating space, and air is mixed as required to adjust the temperature of the high-temperature flue gas to the required preheating temperature.

13. A pyrolysis recovery device for waste photovoltaic modules, characterized in that: comprising a preheating unit (10), which is a sealable chamber, equipped with a heating mechanism or connected to an external heat source; a pore-forming unit (20), which is a sealable chamber, with a steam spray head group distributed at the top and / or bottom, and is provided with a first pyrolysis gas outlet pipe (63); a pyrolysis unit (30), which is a sealable chamber, equipped with a heating mechanism, connected to the first pyrolysis gas outlet pipe (63), and is provided with a second pyrolysis gas outlet pipe (32); a heat preservation unit (40), which is a sealable chamber, equipped with a temperature regulating mechanism; a pyrolysis gas treatment unit (50) for harmlessly treating the pyrolysis gas; a superheated steam supply unit (60) for producing superheated steam and providing superheated steam for the pore-forming unit (20); The preheating unit (10), the pore-forming unit (20), the pyrolysis unit (30), and the heat preservation unit (40) are all provided with access channels (90) to facilitate the entry and exit of the waste photovoltaic modules (80).

14. The pyrolysis recovery device for waste photovoltaic modules according to claim 13, characterized in that: the preheating unit (10), the pore-forming unit (20), the pyrolysis unit (30), and the heat preservation unit (40) are provided with respective independent conveying platforms (70), and the conveying platforms (70) are connected in sequence to realize the sequential transfer of the waste photovoltaic modules (80).

15. The pyrolysis recovery device for waste photovoltaic modules according to claim 13, characterized in that: the steam spray head group is formed by arranging a plurality of steam spray heads (62) in combination.

16. The pyrolysis recovery device for waste photovoltaic modules according to claim 13, characterized in that: a stirring fan (33) is arranged on the side wall of the pyrolysis unit (30) to promote the gas flow in the pyrolysis unit (30).

17. The pyrolysis recovery device for waste photovoltaic modules according to claim 13, characterized in that: the heating mechanism is a heating jacket, the pyrolysis gas treatment unit (50) includes a combustion chamber, the pyrolysis gas is harmlessly treated by combustion in the combustion chamber, and the high-temperature flue gas generated by the combustion chamber is used to provide heat for the heating mechanisms of the pyrolysis unit (30) and the preheating unit (10); it also includes a flue gas tail gas treatment unit (51).

18. The pyrolysis recovery device for waste photovoltaic modules according to claim 17, characterized in that: The flue gas and tail gas treatment unit (51) includes a heat exchanger (511), and a cooling water collector (512) is provided below the heat exchanger (511); the temperature regulating mechanism of the heat preservation unit (40) includes a temperature regulating air supply pipeline (41), and the external air and the flue gas and tail gas are conveyed to the temperature regulating air supply pipeline (41) after heat exchange through the heat exchanger (511).

19. The pyrolysis recovery device for waste photovoltaic modules according to claim 13, characterized in that: the heating mechanism is a heating rod (34), and the heating rod (34) is horizontally arranged in the preheating unit (10) and the pyrolysis unit (30).

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