Waste photovoltaic panel pyrolysis recovery system and method

Abstract

The invention provides a waste photovoltaic panel pyrolysis recovery system and method, and relates to the technical field of photovoltaic panel pyrolysis, the waste photovoltaic panel pyrolysis recovery system comprises a pretreatment unit and a pyrolysis furnace, the pretreatment unit comprises a disassembling machine, a crusher and a magnetic separator which are connected in sequence, the disassembling machine is used for disassembling an aluminum frame and a junction box on a waste photovoltaic panel, and the crusher is used for crushing the aluminum frame and the junction box on the waste photovoltaic panel; the crusher is used for crushing waste photovoltaic panels into particles and separating most of back plates on the waste photovoltaic panels, and the magnetic separator is used for magnetically separating and recycling ferromagnetic materials in the crushed particles; the pyrolyzing furnace is connected with the magnetic separator and is provided with a heat source inlet, the heat source inlet is suitable for being communicated with a flue of a coal-fired power plant, so that a heat source is provided for the pyrolyzing furnace by flue gas of the coal-fired power plant, and the pyrolyzing furnace is used for pyrolyzing EVA adhesive films in broken particles so as to separate glass fragments from silicon wafers. The flue gas waste heat of the coal-fired power plant can be used for providing heat for pyrolysis of the waste photovoltaic panel, the energy consumption of pyrolysis of the photovoltaic panel is reduced, and the recovery cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic panel pyrolysis technology, and in particular to a pyrolysis recycling system and method for waste photovoltaic panels. Background Technology

[0002] Photovoltaic power generation is widely used as a renewable energy technology. After photovoltaic modules are retired, the glass, aluminum, silver, silicon and other materials in the photovoltaic modules have high recycling value. However, the recycling process of photovoltaic modules often faces the challenge of how to process the photovoltaic modules in layers, that is, how to remove the EVA film.

[0003] To achieve the peeling of EVA film, the relevant technologies mainly employ physical separation methods, chemical solvent methods, and pyrolysis methods. Among them, pyrolysis is a method that uses heating to decompose organic materials such as EVA film to separate glass and battery cells. Compared with the other two methods, this method has advantages such as high recycling efficiency, high material purity, convenience and speed, and suitability for industrial production. However, pyrolysis generally consumes more energy and is prone to releasing harmful gases during the process. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, one embodiment of the present invention proposes a waste photovoltaic panel pyrolysis recycling system, which can utilize the waste heat of flue gas from coal-fired power plants to provide heat for the pyrolysis of waste photovoltaic panels, thereby saving energy consumption in photovoltaic panel pyrolysis and reducing recycling costs.

[0006] Another embodiment of the present invention proposes a method for the pyrolysis recycling of waste photovoltaic panels.

[0007] A waste photovoltaic panel pyrolysis recycling system according to an embodiment of the present invention includes a pretreatment unit and a pyrolysis furnace. The pretreatment unit includes a dismantling machine, a crusher, and a magnetic separator connected in sequence. The dismantling machine is used to remove the aluminum frame and junction box from the waste photovoltaic panel. The crusher is used to crush the waste photovoltaic panel into particles and separate most of the backsheet from the waste photovoltaic panel. The magnetic separator is used to magnetically separate and recover ferromagnetic materials from the crushed particles. The pyrolysis furnace is connected to the magnetic separator and is provided with a heat source inlet. The heat source inlet is adapted to be connected to the flue gas duct of a coal-fired power plant so that the flue gas of the coal-fired power plant provides a heat source for the pyrolysis furnace. The pyrolysis furnace is used to pyrolyze the EVA film in the crushed particles to separate glass fragments from silicon wafers.

[0008] According to an embodiment of the present invention, a waste photovoltaic panel pyrolysis recycling system receives the recycled waste photovoltaic panels in a pre-processing unit. The dismantling machine first removes the aluminum frame and junction box from the waste photovoltaic panels. Then, under the crushing action of a crusher, the remaining portion of the waste photovoltaic panels is crushed into particles. Simultaneously, most of the backsheet is separated from the solar cells by mechanical stress. After magnetic separation to remove and recover the ferromagnetic material from the crushed particles, the crushed particles are further transported to a pyrolysis furnace for pyrolysis. In this process, because the heat source inlet of the pyrolysis furnace is connected to the flue gas of a coal-fired power plant, the waste heat from the flue gas of the coal-fired power plant can be coupled to achieve the pyrolysis of the EVA film in the crushed particles within the pyrolysis furnace, thereby separating the glass fragments from the silicon wafers. Therefore, compared to related technologies, the present invention can utilize the waste heat from the flue gas of a coal-fired power plant to provide heat for the pyrolysis of waste photovoltaic panels, saving energy consumption in photovoltaic panel pyrolysis and reducing recycling costs.

[0009] In some embodiments, the heat source inlet includes a low-temperature flue gas inlet and a high-temperature flue gas inlet, wherein the low-temperature flue gas inlet is connected to the flue between the economizer and the air preheater of the coal-fired power plant, and the high-temperature flue gas inlet is connected to the flue between the boiler furnace and the economizer of the coal-fired power plant.

[0010] The pyrolysis furnace includes a low-temperature pyrolysis section and a high-temperature pyrolysis section connected to each other. The low-temperature pyrolysis section is provided with a low-temperature flue gas inlet and is used to decompose the EVA film in the crushed particles. The low-temperature pyrolysis section is connected to the magnetic separator. The high-temperature pyrolysis section is provided with a high-temperature flue gas inlet and is used to oxidize the coke remaining in the EVA film in the crushed particles and decompose the residual backing plate fragments in the crushed particles.

[0011] In some embodiments, the low-temperature pyrolysis section is further provided with a first flue gas outlet, which is connected to the flue between the economizer and the air preheater of the coal-fired power plant. The high-temperature pyrolysis section is further provided with a second flue gas outlet, which is connected to the flue between the boiler furnace and the economizer of the coal-fired power plant.

[0012] In some embodiments, the recycling system further includes a sorting unit, which includes a vibrating screen, a density separator, and an eddy current separator. The vibrating screen is connected to the high-temperature pyrolysis section and is used to screen out glass fragments and silicon wafers from the crushed particles. The density separator is connected to the vibrating screen and is used to separate glass fragments and silicon wafers. The eddy current separator is connected to the density separator and is used to extract and recycle non-ferrous metals.

[0013] In some embodiments, the recycling system further includes a hydrometallurgical unit, which includes an acid leaching tank and an electrolytic cell. The acid leaching tank is connected to the eddy current separator and is used to recover high-value metals from non-ferrous metals. The electrolytic cell is connected to the acid leaching tank and is used to electrolytically purify high-value metals.

[0014] In some embodiments, the pyrolysis furnace is further provided with a pyrolysis gas outlet, and the recovery system further includes a gas purification unit, which is connected to the pyrolysis gas outlet to purify the pyrolysis gas.

[0015] In some embodiments, the gas purification unit includes a cyclone dust collector, an activated carbon adsorption tower, and a defluorination module connected in sequence. The cyclone dust collector is connected to the pyrolysis gas outlet and is used to filter dust in the pyrolysis gas. The activated carbon adsorption tower is used to adsorb adsorbable impurities in the pyrolysis gas. The defluorination module is used to remove fluorides from the pyrolysis gas to obtain purified combustible gas.

[0016] The defluorination module is adapted to be connected to the boiler furnace of a coal-fired power plant to introduce the combustible gas for combustion assistance.

[0017] A method for pyrolytic recycling of waste photovoltaic panels according to an embodiment of the present invention includes the following steps:

[0018] Pre-processing involves removing the aluminum frame and junction box from the waste photovoltaic panels using a dismantling machine. The remaining parts of the waste photovoltaic panels are then placed in a crusher to be crushed into particles. During the crushing process, most of the backsheets are separated from the remaining parts of the waste photovoltaic panels. The crushed particles then enter a magnetic separator, which recovers the ferromagnetic materials from the crushed particles.

[0019] Pyrolysis is performed by using flue gas from a coal-fired power plant to provide heat to a pyrolysis furnace. The pyrolysis furnace pyrolyzes the EVA film in the magnetically separated particles at a set temperature, thereby separating the glass fragments from the silicon wafer.

[0020] The technical advantages of the waste photovoltaic panel pyrolysis recycling method according to the present invention are the same as those of the waste photovoltaic panel pyrolysis recycling system described above, and will not be repeated here.

[0021] Furthermore, in the pretreatment operation, the crusher crushes the waste photovoltaic panels into particles with a diameter of less than 5 cm.

[0022] In some embodiments, the pyrolysis operation specifically includes:

[0023] Low-temperature pyrolysis: The pyrolysis furnace decomposes the EVA film in the crushed particles after magnetic separation at a first set temperature to obtain primary pyrolyzed particles.

[0024] High-temperature pyrolysis: the pyrolysis furnace oxidizes the coke residue of the EVA film in the primary pyrolysis particles, softens the glass fragments, and decomposes the residual backing plate fragments at a second set temperature, wherein the second set temperature is higher than the first set temperature.

[0025] Furthermore, the first set temperature is 300-500℃, and the second set temperature is 600-700℃.

[0026] Furthermore, in the pyrolysis operation, the pyrolysis time of the magnetically separated crushed particles in the pyrolysis furnace is 1 to 2 hours.

[0027] In some embodiments, the recycling method further includes:

[0028] Pyrolysis gas treatment involves passing the pyrolysis gas generated during the pyrolysis operation into a gas purification unit, which sequentially filters the pyrolysis gas to remove dust, adsorbs impurities, and removes fluorides to obtain purified combustible gas.

[0029] The combustible gas is then introduced into the boiler furnace of the coal-fired power plant to aid combustion.

[0030] In some embodiments, after the pyrolysis operation, the recovery method further includes:

[0031] The glass fragments and silicon wafers in the crushed particles are initially separated by a vibrating screen. The glass fragments and silicon wafers are then separated a second time by a density separator. The separated glass fragments and silicon wafers are then fed into an eddy current separator, which extracts non-ferrous metals such as copper and silver.

[0032] Hydrometallurgy involves leaching high-value metals from non-ferrous metals in an acid leaching tank, and then purifying and recycling these high-value metals in an electrolytic cell.

[0033] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a waste photovoltaic panel pyrolysis recycling system according to an embodiment of the present invention.

[0035] Figure 2 This is a schematic flowchart of a pyrolysis recycling method for waste photovoltaic panels according to an embodiment of the present invention.

[0036] Figure label:

[0037] 1. Preprocessing unit;

[0038] 2. Pyrolysis furnace; 21. Heat source inlet; 211. Low-temperature flue gas inlet; 212. High-temperature flue gas inlet; 22. Low-temperature pyrolysis section; 23. High-temperature pyrolysis section; 24. Pyrolysis gas outlet;

[0039] 3. Boiler;

[0040] 4. Flue gas treatment system; 41. Economizer; 42. Air preheater;

[0041] 5. Sorting unit;

[0042] 6. Hydrometallurgical Unit;

[0043] 7. Gas purification unit. Detailed Implementation

[0044] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0045] like Figure 1 As shown in the figure, an embodiment of the present invention provides a waste photovoltaic panel pyrolysis recycling system, including a pretreatment unit 1 and a pyrolysis furnace 2. The pretreatment unit 1 includes a dismantling machine, a crusher, and a magnetic separator connected in sequence. The dismantling machine is used to remove the aluminum frame and junction box from the waste photovoltaic panel. The crusher is used to crush the waste photovoltaic panel into particles and separate most of the backsheet from the waste photovoltaic panel. The magnetic separator is used to magnetically separate and recover the ferromagnetic material in the crushed particles. The pyrolysis furnace 2 is connected to the magnetic separator and is provided with a heat source inlet 21. The heat source inlet 21 is adapted to be connected to the flue of a coal-fired power plant so that the flue gas of the coal-fired power plant provides a heat source for the pyrolysis furnace 2. The pyrolysis furnace 2 is used to pyrolyze the EVA film in the crushed particles to separate the glass fragments from the silicon wafers.

[0046] According to an embodiment of the present invention, a waste photovoltaic panel pyrolysis recycling system receives recycled waste photovoltaic panels in a pretreatment unit 1. The dismantling machine first removes the aluminum frame and junction box from the waste photovoltaic panels. Then, under the crushing action of a crusher, the remaining portion of the waste photovoltaic panels is crushed into particles. Simultaneously, most of the backsheet is separated from the solar cells by mechanical stress. After magnetic separation to remove and recover the ferromagnetic material from the crushed particles, the crushed particles are further transported to a pyrolysis furnace 2 for pyrolysis. In this process, because the heat source inlet 21 of the pyrolysis furnace 2 is connected to the flue gas of a coal-fired power plant, the waste heat from the flue gas of the coal-fired power plant can be coupled to achieve the pyrolysis of the EVA film in the crushed particles within the pyrolysis furnace 2, thereby separating the glass fragments from the silicon wafers. Therefore, compared to related technologies, the present invention can utilize the waste heat from the flue gas of a coal-fired power plant to provide heat for the pyrolysis of waste photovoltaic panels, saving energy consumption in photovoltaic panel pyrolysis and reducing recycling costs.

[0047] It should be noted that photovoltaic modules (i.e., photovoltaic panels) in photovoltaic power generation are generally composed of aluminum frames, junction boxes, tempered glass, EVA film crystalline silicon cells, and TPT backsheets.

[0048] In addition, among related technologies, the "physical method" involves disassembling photovoltaic modules mechanically or manually to separate components such as aluminum frames, junction boxes, and solar cells. This method is environmentally friendly and can be applied on a large scale, but it has high energy consumption and the purity of the separated materials is low. The "chemical solvent method" uses chemical solvents to remove encapsulation materials such as EVA. This method can obtain complete silicon wafers and glass with a high recovery rate, but the reaction time is long and the process is complex, which is not conducive to large-scale production. In contrast, the "pyrolysis method" decomposes organic matter such as EVA by heating to separate glass and solar cells. This method has high recovery efficiency, high material purity, is convenient and fast, and is suitable for industrial production. Therefore, this invention is based on the "pyrolysis method" and coupled with a coal-fired power plant. It can use the waste heat of flue gas from the coal-fired power plant to provide heat to the pyrolysis furnace 2 without consuming additional energy to pyrolyze the EVA film in the crushed particles, which greatly reduces the recycling cost of waste photovoltaic panels.

[0049] like Figure 1 As shown, in some embodiments, the heat source inlet 21 includes a low-temperature flue gas inlet 211 and a high-temperature flue gas inlet 212. The low-temperature flue gas inlet 211 is connected to the flue between the economizer 41 and the air preheater 42 of the coal-fired power plant, and the high-temperature flue gas inlet 212 is connected to the flue between the furnace of the boiler 3 and the economizer 41 of the coal-fired power plant.

[0050] The pyrolysis furnace 2 includes a low-temperature pyrolysis section 22 and a high-temperature pyrolysis section 23 connected to each other. The low-temperature pyrolysis section 22 is equipped with a low-temperature flue gas inlet 211 and is used to decompose the EVA film in the crushed particles. The low-temperature pyrolysis section 22 is connected to a magnetic separator. The high-temperature pyrolysis section 23 is equipped with a high-temperature flue gas inlet 212 and is used to oxidize the coke remaining in the EVA film in the crushed particles and decompose the residual back plate fragments in the crushed particles.

[0051] It is understandable that the flue gas temperature in the flue between the boiler furnace 3 and economizer 41 of a coal-fired power plant is higher than the flue gas temperature in the flue between economizer 41 and air preheater 42 of a coal-fired power plant. That is, the flue gas temperature in the flue at the inlet of economizer 41 is higher than the flue gas temperature in the flue at the outlet of economizer 41. By utilizing the different temperatures of the waste heat of the flue gas in the flues on both sides of economizer 41, different substances in the crushed particles can be processed separately. This structural design simplifies the overall structure of the recycling system and ensures the purity of the recycled materials from waste photovoltaic panels.

[0052] Specifically, a coal-fired power plant includes a boiler 3 and a flue gas treatment system 4. The flue gas treatment system 4 typically includes an economizer 41 and an air preheater 42 connected together. The tail gas outlet of the boiler 3 furnace is connected to the economizer 41, which can realize the treatment of flue gas from the coal-fired power plant.

[0053] In addition, heating tubes can be coiled in the inner cavity of both the low-temperature pyrolysis section 22 and the high-temperature pyrolysis section 23. The heating tubes are connected to the end of the heat source inlet 21 that is away from the flue of the coal-fired power plant, so as to heat the inner cavity of the pyrolysis furnace 2 by means of the heat exchange of the flue gas introduced into the heating tubes. This enables the low-temperature pyrolysis section 22 to decompose the EVA film in the crushed particles, and the high-temperature pyrolysis section 23 to oxidize the coke residue in the EVA film in the crushed particles and decompose the residual back plate fragments. In other words, the crushed particles in the pyrolysis furnace 2 can exchange heat with the heat source (i.e., flue gas) in a non-contact manner.

[0054] like Figure 1 As shown, in some embodiments, the low-temperature pyrolysis section 22 is also provided with a first flue gas outlet (not shown in the figure), which is connected to the flue between the economizer 41 and the air preheater 42 of the coal-fired power plant. The high-temperature pyrolysis section 23 is also provided with a second flue gas outlet (not shown in the figure), which is connected to the flue between the furnace of the boiler 3 and the economizer 41 of the coal-fired power plant.

[0055] It is understandable that when flue gas is drawn from the flue as a heat source to heat the low-temperature pyrolysis section 22 or the high-temperature pyrolysis section 23 before returning to the flue, the crushed particles in the pyrolysis furnace 2 exchange heat with the heat source in a non-contact manner, and the temperature of the heat source will not drop too much after the heat exchange. Therefore, by passing the heat source back to the same section of the flue, the flue gas after the heat exchange can continue to be processed in the flue gas treatment system 4 of the coal-fired power plant, without the need to design a separate flue gas treatment system 4, thus further simplifying the overall structure of the recovery system.

[0056] like Figure 1 As shown, in some embodiments, the recycling system further includes a sorting unit 5, which includes a vibrating screen, a density separator, and an eddy current separator. The vibrating screen is connected to the high-temperature pyrolysis section 23 and is used to screen out glass fragments and silicon wafers from the crushed particles; the density separator is connected to the vibrating screen and is used to sort glass fragments and silicon wafers; the eddy current separator is connected to the density separator and is used to extract and recycle non-ferrous metals.

[0057] Understandably, combined with the above structural design, a two-stage screening system is formed by the vibrating screen and density separator in the sorting unit 5 after the pyrolysis furnace 2. This system can separate glass fragments and silicon wafers from the crushed particles, so that the glass fragments and silicon wafers can be recycled and reused separately. The eddy current separator can be used for coarse extraction and recovery of non-ferrous metals such as copper and silver, thus enabling the full recycling and reuse of waste photovoltaic panels.

[0058] It should be noted that the vibrating screen can achieve coarse screening of glass fragments and silicon wafers, because the density of glass is 2.5 g / cm³. 3 The density of silicon is 2.3 g / cm³. 3 Therefore, glass fragments and silicon wafers can be finely screened using a density sorter to further ensure the purity of glass fragments and silicon wafers.

[0059] like Figure 1 As shown, in some embodiments, the recycling system further includes a hydrometallurgical unit 6, which includes an acid leaching tank and an electrolytic cell. The acid leaching tank is connected to an eddy current separator and is used to recover high-value metals from non-ferrous metals. The electrolytic cell is connected to the acid leaching tank and is used to electrolytically purify high-value metals.

[0060] Understandably, by combining the above structural design with the acid leaching tank and electrolytic cell in hydrometallurgical unit 6, it is possible to further purify and recycle high-value metals such as crude copper and crude silver, thereby completing the separate recycling of glass, silicon wafers and high-value metals, improving product value and shortening the investment payback period.

[0061] Specifically, the acid leaching tank contains an acid solution used to leach out high-value metals.

[0062] like Figure 1 As shown, in some embodiments, the pyrolysis furnace 2 is further provided with a pyrolysis gas outlet 24, and the recovery system further includes a gas purification unit 7, which is connected to the pyrolysis gas outlet 24 to purify the pyrolysis gas.

[0063] Understandably, the gas purification unit 7 can purify the pyrolysis gas generated by the pyrolysis of the photovoltaic panel, thereby reducing environmental pollution and improving the environmental friendliness of the system.

[0064] like Figure 1 As shown, in some embodiments, the gas purification unit 7 includes a cyclone dust collector, an activated carbon adsorption tower, and a defluorination module connected in sequence. The cyclone dust collector is connected to the pyrolysis gas outlet 24 and is used to filter dust in the pyrolysis gas. The activated carbon adsorption tower is used to adsorb adsorbable impurities in the pyrolysis gas. The defluorination module is used to remove fluorides from the pyrolysis gas to obtain purified combustible gas.

[0065] The defluorination module is suitable for connection with the furnace of a coal-fired power plant boiler to introduce combustible gas for combustion assistance.

[0066] Understandably, the pyrolysis gas (or tail gas) generated by the pyrolysis of photovoltaic panels, which is purified by the gas purification unit 7 in conjunction with the flue gas treatment system 4 of the coal-fired power plant, can be directly utilized by the SCR and wet desulfurization systems of the coal-fired power plant, avoiding the need to build new tail gas purification facilities and reducing investment costs. At the same time, since the combustible gas generated by the pyrolysis of photovoltaic panels is introduced into the furnace of boiler 3 for combustion assistance, the calorific value of the pyrolysis of photovoltaic panels can also be fully utilized. The calorific value of the pyrolysis gas is estimated to be about 1.5 MJ / kg photovoltaic panel, which can completely make up for the heat consumed by the pyrolysis of photovoltaic panels (1.16 MJ / kg photovoltaic panel).

[0067] like Figure 2 As shown in the figure, a method for pyrolysis recycling of waste photovoltaic panels according to an embodiment of the present invention includes the following steps:

[0068] Step S1, pre-processing: The aluminum frame and junction box on the waste photovoltaic panel are removed by the dismantling machine. The remaining part of the waste photovoltaic panel is placed in the crusher and crushed into particles. During the crushing process, most of the back panel is separated from the remaining part of the waste photovoltaic panel. The crushed particles enter the magnetic separator, which recovers the ferromagnetic material in the crushed particles.

[0069] Step S2, pyrolysis, where the flue gas from the coal-fired power plant provides a heat source for the pyrolysis furnace 2. The pyrolysis furnace 2 pyrolyzes the EVA film in the magnetically separated particles at a set temperature to separate the glass fragments from the silicon wafer.

[0070] The technical advantages of the waste photovoltaic panel pyrolysis recycling method according to the present invention are the same as those of the waste photovoltaic panel pyrolysis recycling system described above, and will not be repeated here.

[0071] Furthermore, in step S1, the crusher crushes the waste photovoltaic panels into particles with a diameter of less than 5 cm.

[0072] In some embodiments, step S2 specifically includes:

[0073] Step S21, low-temperature pyrolysis: pyrolysis furnace 2 decomposes the EVA film in the crushed particles after magnetic separation at a first set temperature to obtain primary pyrolysis particles.

[0074] Step S22, high-temperature pyrolysis, the pyrolysis furnace 2 oxidizes the coke residue of the EVA film in the primary pyrolysis particles, softens the glass fragments, and decomposes the residual backing plate fragments at a second set temperature, wherein the second set temperature is higher than the first set temperature.

[0075] Furthermore, the first set temperature is 300–500°C, and the second set temperature is 600–700°C.

[0076] Furthermore, in step S2, the pyrolysis time of the crushed particles after magnetic separation in the pyrolysis furnace 2 is 1 to 2 hours.

[0077] like Figure 2 As shown, in some embodiments, the recycling method further includes:

[0078] Step S2', pyrolysis gas treatment: The pyrolysis gas generated during the pyrolysis operation is passed into the gas purification unit 7. The gas purification unit 7 filters the pyrolysis gas to remove dust, adsorb impurities and remove fluorides in sequence to obtain purified combustible gas.

[0079] Step S2”, reuse, the combustible gas is introduced into the furnace of boiler 3 of the coal-fired power plant to aid combustion.

[0080] like Figure 2 As shown, in some embodiments, after step S2, the recycling method further includes:

[0081] Step S3, sorting: The glass fragments and silicon wafers in the crushed particles are initially screened by a vibrating screen. The obtained glass fragments and silicon wafers are then sorted a second time by a density separator. The sorted glass fragments and silicon wafers enter an eddy current separator, which extracts non-ferrous metals such as copper and silver.

[0082] Step S4, hydrometallurgy, involves leaching high-value metals from non-ferrous metals in an acid leaching tank, and then purifying and recycling the high-value metals in an electrolytic cell.

[0083] Therefore, in some embodiments of the present invention, the pyrolysis recycling method for waste photovoltaic panels includes steps S1 and S2; in other embodiments, the pyrolysis recycling method for waste photovoltaic panels includes steps S1, S2, S2', and S2"; in still other embodiments, the pyrolysis recycling method for waste photovoltaic panels includes steps S1, S2, S2', S2", S3, and S4. It should be noted that in this embodiment, steps S2' and S2" and step S3 are two processes following step S2, that is, the two processes are performed in parallel. In other words, the pyrolysis recycling method for waste photovoltaic panels of the present invention can be any of the three methods mentioned above.

[0084] The present invention will be further illustrated by specific embodiments below.

[0085] Example 1

[0086] A method for pyrolysis recycling of waste photovoltaic panels, based on the above system, includes the following steps:

[0087] 1) The recycled complete waste photovoltaic panels are sent to the pre-processing unit 1. After the aluminum frame and junction box are removed by the dismantling machine, the remaining part of the waste photovoltaic panels is sent to the crusher. The crusher crushes the remaining part of the waste photovoltaic panels into particles with a particle size of less than 5cm. At the same time, most of the fluorine-containing backsheets are separated from the cells by mechanical stress and then magnetically separated by the magnetic separator to remove and recycle ferromagnetic materials.

[0088] 2) The crushed particles are fed into pyrolysis furnace 2. The crushed particles stay in pyrolysis furnace 2 for about 1.5 hours. The low-temperature zone at the front of pyrolysis furnace 2 (i.e., low-temperature pyrolysis section 22) introduces flue gas from the outlet section of economizer 41 of the coal-fired power plant to control the furnace temperature at 450°C. At this time, the EVA film in the crushed particles decomposes in the low-temperature zone at the front of pyrolysis furnace 2 to produce combustible gas. After that, the crushed particles further enter the high-temperature zone at the rear of pyrolysis furnace 2. Flue gas from the inlet section of economizer 41 is introduced to control the rear temperature at 650°C. This allows the coke remaining after the pyrolysis of the EVA film in the crushed particles to be further oxidized in the high-temperature zone. The glass in the crushed particles softens and separates from the silicon wafer. The remaining backplate further decomposes and releases fluorine-containing gas. The aforementioned gases (excluding flue gas) enter the gas purification unit 7 for purification.

[0089] 3) The solid material from step 2) above is fed into the sorting unit 5. Under the action of the vibrating screen and density separator, glass fragments and silicon wafers are separated, while the eddy current separator extracts non-ferrous metals such as crude silver and crude copper.

[0090] 4) After that, the crude silver and crude copper further enter the hydrometallurgical unit 6, where high-value metals are extracted by acid leaching in the acid leaching tank, and then recycled after electrolytic purification in the electrolytic cell.

[0091] In addition, in step 2) above, the pyrolysis gas entering the gas purification unit 7 first removes dust and adsorbable impurities from the pyrolysis gas under the action of dust collector and activated carbon adsorption, and then removes fluorides through the defluorination module, and the purified combustible gas is delivered to the boiler 3 for combustion assistance.

[0092] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0093] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0094] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0095] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0096] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0097] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A pyrolysis recycling system for waste photovoltaic panels, characterized in that, include: The pretreatment unit includes a dismantling machine, a crusher, and a magnetic separator connected in sequence. The dismantling machine is used to remove the aluminum frame and junction box from the waste photovoltaic panel. The crusher is used to crush the waste photovoltaic panel into particles and separate most of the backsheet from the waste photovoltaic panel. The magnetic separator is used to magnetically separate and recover the ferromagnetic material from the crushed particles. A pyrolysis furnace is connected to the magnetic separator and is provided with a heat source inlet. The heat source inlet is adapted to be connected to the flue of a coal-fired power plant so that the flue gas of the coal-fired power plant provides a heat source for the pyrolysis furnace. The pyrolysis furnace is used to pyrolyze the EVA film in the crushed particles to separate the glass fragments from the silicon wafers.

2. The waste photovoltaic panel pyrolysis recycling system according to claim 1, characterized in that, The heat source inlet includes a low-temperature flue gas inlet and a high-temperature flue gas inlet. The low-temperature flue gas inlet is connected to the flue between the economizer and the air preheater of the coal-fired power plant, and the high-temperature flue gas inlet is connected to the flue between the boiler furnace and the economizer of the coal-fired power plant. The pyrolysis furnace includes a low-temperature pyrolysis section and a high-temperature pyrolysis section connected to each other. The low-temperature pyrolysis section is provided with a low-temperature flue gas inlet and is used to decompose the EVA film in the crushed particles. The low-temperature pyrolysis section is connected to the magnetic separator. The high-temperature pyrolysis section is provided with a high-temperature flue gas inlet and is used to oxidize the coke remaining in the EVA film in the crushed particles and decompose the residual backing plate fragments in the crushed particles.

3. The waste photovoltaic panel pyrolysis recycling system according to claim 2, characterized in that, It also includes a sorting unit, which comprises: A vibrating screen, which is connected to the high-temperature pyrolysis section and is used to screen out glass fragments and silicon wafers from the crushed particles; A density separator, which is connected to the vibrating screen and used to separate glass fragments and silicon wafers; An eddy current separator, which is connected to the density separator and used to extract and recover non-ferrous metals.

4. The waste photovoltaic panel pyrolysis recycling system according to claim 3, characterized in that, It also includes a hydrometallurgical unit, which comprises: An acid leaching tank is connected to the eddy current separator and is used to recover high-value metals from non-ferrous metals. An electrolytic cell is connected to the acid leaching tank, and the electrolytic cell is used for electrolytic purification of high-value metals.

5. The waste photovoltaic panel pyrolysis recycling system according to claim 1, characterized in that, The pyrolysis furnace is also provided with a pyrolysis gas outlet, and the recovery system further includes a gas purification unit, which is connected to the pyrolysis gas outlet to purify the pyrolysis gas.

6. The waste photovoltaic panel pyrolysis recycling system according to claim 5, characterized in that, The gas purification unit includes a cyclone dust collector, an activated carbon adsorption tower, and a defluorination module connected in sequence. The cyclone dust collector is connected to the pyrolysis gas outlet and is used to filter dust in the pyrolysis gas. The activated carbon adsorption tower is used to adsorb adsorbable impurities in the pyrolysis gas. The defluorination module is used to remove fluorides from the pyrolysis gas to obtain purified combustible gas. The defluorination module is adapted to be connected to the boiler furnace of a coal-fired power plant to introduce the combustible gas for combustion assistance.

7. A method for pyrolytic recycling of waste photovoltaic panels, characterized in that, The recycling method includes the following steps: Pre-processing involves removing the aluminum frame and junction box from the waste photovoltaic panels using a dismantling machine. The remaining parts of the waste photovoltaic panels are then placed in a crusher to be crushed into particles. During the crushing process, most of the backsheets are separated from the remaining parts of the waste photovoltaic panels. The crushed particles then enter a magnetic separator, which recovers the ferromagnetic materials from the crushed particles. Pyrolysis is performed by using flue gas from a coal-fired power plant to provide heat to a pyrolysis furnace. The pyrolysis furnace pyrolyzes the EVA film in the magnetically separated particles at a set temperature, thereby separating the glass fragments from the silicon wafer.

8. The method for pyrolytic recycling of waste photovoltaic panels according to claim 7, characterized in that, The pyrolysis operation specifically involves: Low-temperature pyrolysis: The pyrolysis furnace decomposes the EVA film in the crushed particles after magnetic separation at a first set temperature to obtain primary pyrolyzed particles. High-temperature pyrolysis: the pyrolysis furnace oxidizes the coke residue of the EVA film in the primary pyrolysis particles, softens the glass fragments, and decomposes the residual backing plate fragments at a second set temperature, wherein the second set temperature is higher than the first set temperature.

9. The method for pyrolysis recycling of waste photovoltaic panels according to claim 7, characterized in that, The recycling method further includes: Pyrolysis gas treatment involves passing the pyrolysis gas generated during the pyrolysis operation into a gas purification unit, which sequentially filters the pyrolysis gas to remove dust, adsorbs impurities, and removes fluorides to obtain purified combustible gas. The combustible gas is then introduced into the boiler furnace of the coal-fired power plant to aid combustion.

10. The method for pyrolytic recycling of waste photovoltaic panels according to claim 7, characterized in that, Following the pyrolysis operation, the recovery method further includes: The glass fragments and silicon wafers in the crushed particles are initially separated by a vibrating screen. The glass fragments and silicon wafers are then separated a second time by a density separator. The separated glass fragments and silicon wafers are then fed into an eddy current separator, which extracts non-ferrous metals such as copper and silver. Hydrometallurgy involves leaching high-value metals from non-ferrous metals in an acid leaching tank, and then purifying and recycling these high-value metals in an electrolytic cell.

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