Solar cell module recycling system and solar cell module recycling processing method

Abstract

One embodiment of the present invention is a solar cell module recycling system that continuously performs a thermal decomposition process, the solar cell module recycling system comprising: a thermal decomposition furnace that thermally decomposes a solar cell module; a front chamber on the inlet side of the thermal decomposition furnace; a rear chamber on the outlet side of the thermal decomposition furnace; a collection unit that collects gas generated in the thermal decomposition furnace; and an exhaust gas processing unit that processes the gas collected by the collection unit. A conveyor is provided so as to pass through the front chamber, the thermal decomposition furnace, and the rear chamber in the conveyance direction, the conveyor having suction ports in the front chamber and the rear chamber, and supplying the gas collected from the suction ports to the collection unit.

Description

Solar cell module recycling system and solar cell module recycling processing method

[0001] An embodiment of the present invention relates to a solar cell module recycling system and a solar cell module recycling processing method.

[0002] Toward the realization of a low-carbon society, the acceleration of CO ２ emission reduction is progressing through the utilization of renewable energy including solar power generation. While the installation of solar power generation has advanced significantly, the problem of recycling at the time of disposal of solar cell modules has been pointed out.

[0003] A general solar cell module is composed of three members: a plate glass on the front surface, a battery layer on the inner side including cells and a sealing filler for sealing the cells, and a back sheet on the back surface. In the battery layer, electric wires (also referred to as ribbon wires) connecting the solar cell cells are wired. The sealing filler is required to have transparency, flexibility, adhesiveness, tensile strength, weather resistance, and the like, and ethylene-vinyl acetate copolymer (hereinafter abbreviated as "EVA") is generally used, which plays a role of bonding the plate glass, the cells, and the back sheet by heating and pressurizing.

[0004] When such a general solar cell module is heated by an electric furnace or the like in an oxidizing atmosphere, EVA melts at 80 to 120°C, a deacetic acid reaction of EVA occurs around 350°C, and a thermal decomposition reaction of the polyethylene main chain portion occurs rapidly around 450°C. Technologies for recycling solar cell modules utilizing this thermal decomposition reaction are disclosed (see Patent Documents 1 and 2).

[0005] However, since the thermal decomposition reaction at around 450°C occurs explosively, thermally decomposing solar cell modules of about 1m x 2m in size can cause fires and is unsuitable for large-scale applications. To solve this technical problem, a method for recovering solar cell element constituent materials has been disclosed, which includes the steps of transporting the materials to a continuous heat treatment furnace in which the oxygen concentration inside the furnace is maintained at 1.0 volume% to 3.0 volume%, releasing and removing acetic acid gas, a type of EVA decomposition gas, in a preheating decomposition section set at 300 to 400°C, and then removing EVA decomposition gases other than acetic acid in a heat treatment section set at 400 to 550°C to remove the EVA encapsulant from the solar cell element and separate the cell part from the glass substrate (see Patent Document 3).

[0006] Furthermore, the applicant has proposed a solar cell module recycling system comprising a conveyor on which solar cell modules are placed, a pyrolysis furnace for pyrolysis treatment of the solar cell modules placed on the conveyor, and a filter provided in the pyrolysis furnace for oxidative decomposition of the resin that has molten and fallen from the pyrolysis-treated solar cell modules, wherein at least the conveyor is provided to penetrate the pyrolysis furnace in the transport direction and has a plurality of through holes for allowing the resin to molten and fall (see Patent Document 4).

[0007] Japanese Patent Publication No. 11-165150, Japanese Patent Publication No. 2007-59793, Japanese Patent Publication No. 2014-108375, International Publication No. 2024 / 162190, Japanese Patent Publication No. 2021-103047

[0008] Collection of Polymer Papers, Vol. 64. No. 9 (2007)

[0009] The method disclosed in Patent Document 3 involves thermally decomposing resins such as EVA under heating conditions in a non-oxidizing atmosphere or an atmosphere with a very low oxygen concentration to prevent rapid combustion reactions. However, controlling the oxygen concentration and temperature inside the furnace under the conditions of Patent Document 3 is complex and requires considerable technical skill to operate, so it cannot be considered a simple method.

[0010] Furthermore, while the material used for the backsheets of early solar cells, as described in Patent Documents 1 to 3, was mostly weather-resistant polyvinyl fluoride (hereinafter abbreviated as "PVF"), currently, the cheaper polyethylene terephthalate (hereinafter abbreviated as "PET") has become the mainstream. Single-layer PET backsheets, as well as two- or three-layer backsheets such as PVF / PET, PVDF / PET, PVF / PET / PVF, and PVDF / PET / PVDF, which are laminated with fluororesins such as PVF or polyvinylidene fluoride (hereinafter abbreviated as "PVDF"), are widely used, and backsheets using PET now account for the vast majority.

[0011] Fluorine-based resins such as PVF and PVDF decompose at similar temperatures to EVA, so conventional thermal decomposition methods are not problematic. However, PET melts at 250°C, thermal decomposition begins around 400°C, and because it contains benzene rings and ester groups, the thermal decomposition reaction is multifaceted. Carbides with complex bonding between benzene rings are also produced as by-products, sometimes resulting in black "soot," and glass with this soot attached is difficult to reuse. Furthermore, it has been reported that even when burned at 850°C, 9% of the residue remains as soot (see Non-Patent Literature 1).

[0012] Therefore, in the technology described in Patent Document 3 for reducing oxygen concentration, even if EVA can be thermally decomposed, PET is not completely thermally decomposed. As a result, when solar cell modules using PET-containing backsheets are heat-treated, they become covered in soot, and inorganic powders such as titanium dioxide and calcium carbonate contained in the backsheet remain. Therefore, more advanced separation technology is required to recycle valuable materials.

[0013] On the other hand, the technology described in Patent Document 4 involves placing a heat-resistant material on which a transition metal oxide is supported inside a pyrolysis furnace. This makes it possible to handle large-panel solar cell modules and to perform processing that saves fuel and easily recovers valuable materials.

[0014] However, when solar cell modules are continuously heated in an oxidizing atmosphere with an oxygen concentration of 15% or higher, if explosive combustion accompanied by flames occurs in the pyrolysis furnace, a rapid increase in gases generated by the decomposition of the resin and a large amount of smoke are produced. This presents a new challenge: gases and smoke that cannot be processed in the pyrolysis furnace leak to the outside when the furnace is opened or closed.

[0015] Furthermore, we encountered a problem where, if the pyrolysis furnace was opened or closed before the thermal decomposition of the resin was complete, outside air would flow into the furnace through the open section, causing a rapid and large amount of smoke to be generated as the resin being decomposed reacted with the oxygen in the outside air.

[0016] For solar cell modules to be recycled as industrial waste, it is desirable that the gases and smoke generated by combustion are properly treated and not leaked to the outside from anywhere other than the chimney.

[0017] The technology described in Patent Document 3 reduces the oxygen concentration to prevent explosive combustion accompanied by flames during the decomposition of EVA. Therefore, it is thought that it does not face the issues of a rapid increase in gas, massive generation of smoke, and rapid generation of massive amounts of smoke due to the reaction of resin and oxygen in the pyrolysis furnace. Consequently, the gas and smoke countermeasures in the technology described in Patent Document 3 were insufficient.

[0018] In the technology described in Patent Document 5, there is an inlet-side sealing chamber located upstream of the pyrolysis furnace and an outlet-side sealing chamber located downstream. However, these are sealed by suspended sealing curtains, which are insufficient to prevent the rapid outflow of large amounts of gas and smoke to the outside.

[0019] Furthermore, in the technology described in Patent Document 5, when continuous heating is performed, the temperature inside the pyrolysis furnace drops too low when the furnace is opened and closed, requiring the furnace to be heated again, which results in a lot of wasted fuel.

[0020] Based on the above, one embodiment of the present invention provides a solar cell module recycling system and a solar cell module recycling method that suppress the leakage of gases and smoke generated during pyrolysis treatment to the outside, save fuel, and perform continuous pyrolysis treatment in order to appropriately recycle solar cell modules as industrial waste and recover valuable materials.

[0021] The inventors diligently studied to solve the aforementioned problems. As a result, they have completed the present invention. An example of the configuration of one embodiment of the present invention is as follows.

[0022] [1] A solar cell module recycling system for which solar cell modules mounted on a collection network are placed on a conveyor and continuously subjected to thermal decomposition treatment, comprising: a thermal decomposition furnace for thermal decomposition treatment of solar cell modules mounted on the collection network; a front chamber on the inlet side of the thermal decomposition furnace; a rear chamber on the outlet side of the thermal decomposition furnace; a collection unit for collecting gas generated in the thermal decomposition furnace; and an exhaust gas processing unit for processing the gas collected in the collection unit, wherein the conveyor is provided to penetrate the front chamber, the thermal decomposition furnace, and the rear chamber in the transport direction, and has suction ports in the front chamber and the rear chamber, and supplies the gas collected from the suction ports to the collection unit. [2] The solar cell module recycling system according to [1], wherein the exhaust gas processing unit has at least an augmenter.

[0023] [3] The solar cell module recycling system according to [1] or [2], wherein the suction port is located on the top surface of the front chamber and the rear chamber. [4] The solar cell module recycling system according to any one of [1] to [3], wherein the gas collected from the suction port is outside air in addition to the gas and / or smoke generated in the pyrolysis furnace.

[0024] A solar cell module recycling method comprising: a pyrolysis step of pyrolysis the solar cell module in a pyrolysis furnace according to any one of [5] [1] to [4]; a transport step of transporting the solar cell module mounted on a recovery net together with the recovery net after the pyrolysis step; a valuable material recovery step of recovering valuable materials from the pyrolysis-treated solar cell module after the transport step; and an exhaust gas treatment step of treating the gas generated in the pyrolysis furnace. [6] The solar cell module recycling method according to [5], further comprising a loading step of stacking filters on a tray, loading a recovery net on the filters, and loading solar cell modules on the recovery net before the pyrolysis step.

[0025] [7] The solar cell module recycling method according to [5] or [6], wherein the thermal decomposition treatment is carried out in an oxidizing atmosphere. [8] The solar cell module recycling method according to any one of [5] to [7], wherein the valuable material is at least one selected from the group consisting of glass, ribbon wire, silicon, silver, copper, titanium oxide, and calcium carbonate.

[0026] According to one embodiment of the present invention, a solar cell module recycling system and a solar cell module recycling method can be provided that suppress the leakage of gases and smoke generated during pyrolysis to the outside, save fuel, and continuously perform pyrolysis in order to properly recycle solar cell modules as industrial waste and recover valuable materials.

[0027] This is a schematic diagram showing a solar cell module. (a) is a plan view of the solar cell module, and (b) is a cross-sectional view of the solar cell module. This is a schematic diagram of a solar cell module mounted on a recovery network showing one embodiment of the present invention. This is a schematic diagram of a pyrolysis furnace showing one embodiment of the present invention. This is a schematic diagram showing a solar cell module recycling system and a solar cell module recycling method using the system showing one embodiment of the present invention. This is the temperature history inside the pyrolysis furnace of Example 1 showing one embodiment of the present invention. This is a photograph of the solar cell module and its frame used in Example 1 showing one embodiment of the present invention, and a photograph of the glass plate, cells, ribbon wire, and terminal box recovered after the solar cell module was pyrolyzed.

[0028] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate.

[0029] <Solar Cell Module Recycling System> A solar cell module recycling system according to one embodiment of the present invention is a solar cell module recycling system that places solar cell modules mounted on a collection network onto a conveyor and continuously performs pyrolysis processing. As shown in Figures 2 to 4, the solar cell module recycling system 16, which is one embodiment of the present invention, is equipped with a front chamber 22 on the inlet side of the pyrolysis furnace 20 and a rear chamber 26 on the outlet side of the pyrolysis furnace. Solar cell modules 2 mounted on the collection network 40 are placed on a conveyor in the mounting zone 18 and proceed in the transport direction in the order of front chamber 22, pyrolysis furnace 20, and rear chamber 26, and are continuously subjected to pyrolysis processing. The system is equipped with an exhaust gas processing unit 90 that supplies gas generated in the pyrolysis furnace 20, as well as gas collected from the front chamber suction port 22c and the rear chamber suction port 26c, to a collection unit 80 and processes the collected gas.

[0030] [Pyrolysis Furnace] The pyrolysis furnace is the area where the solar cell modules mounted on the recovery network are subjected to pyrolysis. In this specification, the inside of the pyrolysis furnace is also referred to as the furnace interior, and the area outside the pyrolysis furnace is also referred to as the furnace exterior. It is preferable that the solar cell modules mounted on the recovery network are subjected to pyrolysis while moving inside the furnace from the inlet side to the outlet side, and to increase the processing efficiency, it is even more preferable to move multiple solar cell modules continuously so that multiple solar cell modules are being subjected to pyrolysis inside the pyrolysis furnace. Alternatively, in order to increase the efficiency of the pyrolysis process, the solar cell modules mounted on the recovery network may be left to stand for a certain period of time while being heated in the pyrolysis furnace from the inlet side to the outlet side, and then moved after the pyrolysis process is completed.

[0031] In a pyrolysis furnace, it is preferable that the furnace interior includes a heating section where the temperature of the solar cell module rises, a combustion section where the resin undergoes oxidative decomposition (combustion), and a cooling section where the temperature of the solar cell module decreases. Normally, the inlet side of a pyrolysis furnace is the heating section and the outlet side is the combustion section. However, in one embodiment of the present invention, as the solar cell module moves from the inlet side of the pyrolysis furnace through the central section to the outlet side, it is preferable that the temperature rises from the inlet side to become the heating section, the combustion section in the central section reaches the maximum temperature, and the outlet side becomes the cooling section. This temperature configuration makes it easier to prevent gases and smoke generated by the oxidative decomposition (combustion) of the resin from leaking out of the pyrolysis furnace.

[0032] The boundaries between the heating section, combustion section, and cooling section within a pyrolysis furnace do not need to be clearly defined as long as the resin melts and undergoes oxidative decomposition. For example, the temperature range of the heating section can be 350°C or higher and less than 450°C, the temperature range of the combustion section can be 450°C or higher and less than 750°C, and the temperature range of the cooling section can be 450°C or higher and less than 550°C.

[0033] The inventors have been studying how to prevent gas and smoke from leaking to the outside, even in the event of a large generation of gas and smoke due to violent combustion accompanied by an explosion during the pyrolysis process in a pyrolysis furnace. Initially, the operation involved monitoring the temperature at the outlet side of the pyrolysis furnace and transporting the solar cell modules from the furnace to the outside after the temperature had cooled to below a predetermined level. However, even when the temperature at the outlet side of the pyrolysis furnace had sufficiently decreased (specifically, when the temperature at the outlet side of the pyrolysis furnace was below 500°C), the furnace may still be filled with gas and smoke, and gas and smoke would leak to the outside when the pyrolysis furnace was opened and closed, so further advanced studies were needed.

[0034] The inventors conducted further studies and succeeded in predicting whether a large amount of gas and smoke would be generated during the pyrolysis process by monitoring the temperature of the combustion section inside the pyrolysis furnace (Figure 325). They found that if the temperature range of the combustion section exceeds a predetermined temperature and does not cool down for a certain period of time, it is preferable not to transport the material to be processed inside the pyrolysis furnace to the outside in order to prevent gas and smoke from leaking to the outside.

[0035] The temperature range of the combustion section within the pyrolysis furnace can be appropriately changed depending on the desired pyrolysis processing time, the size of the pyrolysis furnace, etc. However, in one embodiment of the present invention, it is preferable not to transport the solar cell modules from the pyrolysis furnace to the outside of the furnace until the temperature range of the combustion section exceeds 550°C and then cools down to below 500-550°C, that is, until the temperature range of the combustion section is between 500°C and 550°C. This configuration is particularly effective in preventing gas and smoke from leaking to the outside.

[0036] The temperature range of the combustion section can be measured anywhere that allows for the measurement of the highest temperature reached by the solar cell module during the pyrolysis process, but the upper center of the pyrolysis furnace is preferred. Alternatively, the temperature range of the combustion section can also be measured by pre-installing a temperature measuring device on the recovery network, preferably the recovery apparatus, on which the solar cell modules to be pyrolyzed are mounted.

[0037] The term "combustion" in the present invention refers to an oxidation reaction in which organic substances such as EVA and PET contained in the backsheet and sealing filler constituting a solar cell module react with oxygen in the atmosphere.

[0038] Therefore, the combustion temperature is appropriately determined according to the resin constituting the backsheet, and is preferably 450 to 550°C. If the temperature is 450°C or higher, it becomes higher than the thermal decomposition temperatures of EVA and PET, allowing combustion to occur. If the temperature is 550°C or lower, rapid combustion can be suppressed, and breakage of the glass of the solar cell module can be prevented.

[0039] The combustion time is appropriately determined according to the combustion temperature and the thermal decomposition treatment of the resin constituting the backsheet, and is preferably 9 minutes to 30 minutes, more preferably 12 minutes to 21 minutes. For conventional waste solar cell modules, if the time is 12 minutes or longer, the thermal decomposition treatment proceeds sufficiently, making it difficult for gas and smoke in the pyrolysis furnace to leak to the outside.

[0040] It should be noted that melting of resins such as EVA and PET starts to occur at a temperature lower than the above combustion temperature. In order to reach the combustion temperature, it is preferable to raise the temperature of the solar cell module before it enters the pyrolysis furnace. Specifically, it is more preferable to raise the temperature of the solar cell module using a heat insulating tank, and to raise the temperature of the solar cell module using a front chamber.

[0041] The thermal decomposition treatment should be performed in a pyrolysis furnace in consideration of exhaust gas treatment and other factors. The heating device for heating the pyrolysis furnace is not particularly limited as long as it can achieve the combustion temperature and can accommodate the solar cell module mounted on a recovery mesh. Examples of such heating devices include gas furnaces and electric furnaces.

[0042] When the heating device for heating the pyrolysis furnace is a gas furnace, a method of heating an oxygen-containing gas with a gas burner or the like and circulating it inside the gas furnace can be mentioned. Examples of the oxygen-containing gas include a mixed gas of combustible gas such as LP gas and city gas and air.

[0043] In the pyrolysis treatment, it is preferable to control the oxygen concentration in the pyrolysis furnace within the range of 6 vol% or more and less than 15 vol%. This is because the resin can be removed by gentle and stable combustion. The lower limit of the oxygen concentration is preferably 7 vol%, more preferably 8 vol%, and the upper limit is preferably 14.8 vol%, more preferably 14.5 vol%. Even if the oxygen concentration temporarily deviates from the above range, there is no particular operational problem as long as it can be controlled immediately.

[0044] The method for controlling the oxygen concentration in the pyrolysis furnace is not particularly limited. For example, in the case of a gas furnace using a mixed gas of LP gas and air as the oxygen-containing gas, the mixing ratio of air can be adjusted according to the oxygen concentration in the furnace.

[0045] [Front Chamber, Rear Chamber] The front chamber is an area provided on the inlet side of the pyrolysis furnace. The rear chamber is an area provided on the outlet side of the pyrolysis furnace. The solar cell module mounted on the recovery net is transferred by a conveyor and carried into the front chamber. Next, the solar cell module carried into the pyrolysis furnace and subjected to pyrolysis treatment in the pyrolysis furnace is carried into the rear chamber.

[0046] It is preferable that the front chamber and the rear chamber are in a state where outside air is blocked when carrying the solar cell module into the pyrolysis furnace. In addition, the front chamber and the rear chamber are preferably provided with opening / closing members on the inlet side and the outlet side. When the front chamber and the rear chamber are provided with opening / closing members, the inflow of outside air into the chambers can be suppressed, the outside air flowing from the front chamber and the rear chamber into the pyrolysis furnace when opening and closing the pyrolysis furnace can be reduced, and the generation of a large amount of gas and smoke can be suppressed. Furthermore, when the front chamber and the rear chamber are provided with opening / closing members, the direct inflow of outside air into the pyrolysis furnace can be suppressed, so that a decrease in furnace temperature when opening and closing the pyrolysis furnace can be suppressed.

[0047] The reason why a large amount of smoke is generated when outside air flows into the pyrolysis furnace is considered to be that oxygen contained in the outside air reacts with resins contained in the back sheet, sealing filler and the like during the pyrolysis process.

[0048] The opening and closing mechanism is not particularly limited as long as it suppresses the inflow of outside air into the front and rear chambers and is resistant to deterioration by heat (specifically around 500°C). Examples include shutters and clamps, and iron is preferred. When using a shutter as the opening and closing mechanism, it is preferable to suspend it with a chain or the like and open and close it vertically.

[0049] It is preferable that the solar cell modules loaded onto the recovery network have the opening mechanism on the front chamber entrance side open, are transported to the front chamber by a conveyor, and then the opening mechanism on the front chamber entrance side closes. This is to suppress the inflow of outside air into the front chamber. It is preferable that the solar cell modules transported to the front chamber have the opening mechanism on the front chamber entrance side closed, and the opening mechanism on the front chamber exit side (i.e., closer to the pyrolysis furnace entrance side) open, and are transported to the pyrolysis furnace for pyrolysis treatment. This is from the viewpoint of preventing gas and smoke from leaking to the outside.

[0050] It is preferable that after the solar cell modules loaded onto the recovery network have undergone pyrolysis treatment, the opening / closing mechanism on the rear chamber entrance side is open with the rear chamber exit side closed, and the modules are transported to the rear chamber by conveyor, after which the opening / closing mechanism on the rear chamber entrance side is closed. This is from the viewpoint of preventing gas and smoke from leaking to the outside. It is preferable that the pyrolysis-decomposed solar cell modules transported to the rear chamber are transported with the opening / closing mechanism on the rear chamber exit side open with the opening / closing mechanism on the rear chamber entrance side (i.e., the side closer to the pyrolysis furnace exit) closed. This is from the viewpoint of preventing gas and smoke from leaking to the outside.

[0051] The temperature of the pre-chamber is preferably 100 to 200°C, and more preferably 110 to 190°C, from the viewpoint of preheating the solar cell modules mounted on the recovery network to improve the thermal efficiency of the subsequent pyrolysis process. The pre-chamber may be heated by a heater or the like, but it is preferable to raise the temperature to the above level by preheating the trays and filters that have undergone pyrolysis.

[0052] The temperature in the rear chamber is preferably 100 to 300°C, and more preferably 200 to 300°C. This is because the trays and filters can be kept warm, and the heat can be used to preheat the solar cell modules that will be subjected to the subsequent thermal decomposition treatment.

[0053] When pyrolysis processing of solar cell modules using the recovery equipment described later, it is preferable not to cool the post-processing chamber. This is because, after pyrolysis, the solar cell modules are transported together with the recovery network, while the recovery equipment is loaded with solar cell modules again and transported back into the pyrolysis furnace. By not cooling the post-processing chamber, it is not necessary to heat the recovery equipment again, and the thermal efficiency can be improved.

[0054] [Suction Ports] Suction ports are located in the front and rear chambers. The suction ports supply the collected gas to the collection unit described later. By supplying the gas to the collection unit from the suction ports in the front and rear chambers, it is possible to prevent gas and smoke generated by the pyrolysis process from leaking to the outside when the pyrolysis furnace is opened and closed. It is preferable that the suction ports be located on the top surface of the front and rear chambers, because the gas generated by the pyrolysis process is lighter than air. Multiple suction ports may be provided in the front and rear chambers.

[0055] If "smoke overflow" or "smoke residue" occurs in the pyrolysis furnace that cannot be completely exhausted, the smoke can be intentionally introduced into the front chamber and / or rear chamber, and the smoke-containing gas can be supplied to the collection unit through the suction ports in the front and rear chambers. Having suction ports in the front and rear chambers prevents smoke that cannot be completely exhausted from the pyrolysis furnace from leaking to the outside, thereby enhancing the safety of the waste treatment facility.

[0056] The gas collected from the suction port is preferably outside air in addition to the gas and / or smoke generated in the pyrolysis furnace. This is from the viewpoint of preventing outside air from flowing into the pyrolysis furnace from the pre-chamber or post-chamber, and from preventing gas and / or smoke from leaking to the outside.

[0057] [Collection Section] The collection section is a region that collects gases generated in the pyrolysis furnace, as well as gases collected from the suction ports of the pre-chamber and post-chamber. Preferably, the collection section also collects smoke generated in the pyrolysis furnace, and preferably includes piping and an air conditioning control unit (not shown).

[0058] The air conditioning control unit preferably has a function to adjust the flow rate of gas, smoke, outside air, etc., collected in the collection unit, and it is preferable that the gas, smoke, outside air, etc., collected in the collection unit be supplied to a heating device that heats the pyrolysis furnace and / or to an exhaust gas processing unit, which will be described later. Examples of air conditioning control units include dampers and induced draft fans. There may also be multiple air conditioning control units. From the viewpoint of precisely controlling the atmosphere of the front and rear chambers and supplying gas to the collection unit, it is preferable to install the air conditioning control units near the intake port of the front chamber and near the intake port of the rear chamber.

[0059] When using an induced draft fan (not shown) as an air conditioning control device, the exhaust volume should be appropriately adjusted depending on the size of the front or rear chamber and the amount of gas generated in the pyrolysis furnace. From the viewpoint of preventing gas and smoke flowing into the front or rear chamber from leaking to the outside and reducing the running costs of the induced draft fan, the exhaust volume of the induced draft fan should be 4.0 to 60.0 m³. ３ Preferably 25.0 to 30.0 m / min. ３ / min is more preferable, 26.5 to 28.5 m ３ / minutes is even more preferable.

[0060] [Exhaust Gas Processing Unit] The exhaust gas processing unit is the area that processes the collected gas. Preferably, the exhaust gas processing unit processes smoke in addition to gas. Preferably, the exhaust gas processing unit has the function of removing harmful substances contained in the gas, smoke, etc. generated by the thermal decomposition process of the solar cell module. Preferably, the exhaust gas processing unit has at least an augmenter. The configuration of the exhaust gas processing unit can be appropriately changed depending on the type of harmful substance, but for example, it may further include a heat exchange unit with a heat exchanger, a dust collection unit with a dust collector, and a hydrogen fluoride removal unit with a hydrogen fluoride removal device. Note that the absence of gas and smoke generated during the thermal decomposition process from flowing to the outside can be confirmed, for example, by visual inspection or an infrared sensor.

[0061] [Solar Cell Modules] Any solar cell module with a resin backsheet that is not a double-sided glass type can be used. Specifically, examples of solar cell modules include monocrystalline silicon solar cells, polycrystalline silicon solar cells, amorphous silicon solar cells, heterojunction solar cells, CIS solar cells, CIGS solar cells, and CdTe solar cells.

[0062] The solar cell module frame may be removed before the thermal decomposition process, or it may be removed after the thermal decomposition process to reduce the possibility of glass breakage during removal. However, it is preferable to remove it before the thermal decomposition process due to the advantages of better thermal efficiency and easier work.

[0063] [Recovery Net] The recovery net is used to mount the solar cell modules. There are no particular restrictions on the recovery net as long as it can mount the solar cell modules, but for example, it is made of iron for its robustness and preferably has a suspension section for suspension. Furthermore, the recovery net is preferably mesh in shape from the viewpoint of easily allowing the sealing filler and resin contained in the backsheet to fall into the first filter described later during the thermal decomposition process, from the viewpoint of ensuring gaps to accelerate the thermal decomposition process, and from the viewpoint of reducing weight.

[0064] - Recovery device: The recovery device is preferably used together with the recovery network. The recovery device is preferably equipped with a first filter, a second filter, and a tray. The recovery device is preferably stacked in the order of first filter, second filter, and tray from top to bottom and ready to use. It is preferable that the recovery network is placed on the top layer of the recovery device, i.e., the first filter, and that the solar cell module is placed on top of the recovery network. In this invention, when simply referred to as "filter," it refers to both the first filter and the second filter.

[0065] - First filter The first filter is preferably stable at the combustion temperature described later (specifically, around 425°C to 575°C) and has a porous structure. Specific materials include stable and common ceramic materials such as alumina, zirconia, silicon nitride, silicon carbide, cordierite, ferrite, barium titanate, lead zirconate titanate, forsterite, zircon, mullite, steatite, and aluminum nitride, with silicon carbide being preferred.

[0066] There are no particular restrictions on the pore size of the porous structure, but a size of approximately 0.1 to 5 mm is preferred because it allows for easy penetration when EVA and PET melt at around 450°C. There are no particular restrictions on the number of cells on the surface, but a size of 5 to 50 pixels per inch (hereinafter also referred to as "ppi") is preferred. There are no restrictions on the porosity, but a size of approximately 50 to 95% is preferred, and a three-dimensional skeletal structure with continuous pores is more preferred.

[0067] There are no particular restrictions on the shape of the first filter, but a plate-like shape is preferred in order to prevent the resin used in the solar cell module from falling off. Furthermore, from the viewpoint of suppressing the generation of soot caused by the leakage of molten resin components to the outside of the first filter, it is preferable that the first filter be as large as possible within the size (area) of the surface of the solar cell module.

[0068] - Second filter The second filter is preferably the first filter described above on which a transition metal oxide is supported. This is because, in its oxidized state, the transition metal oxide has the ability to adsorb oxygen and decompose carbon monoxide and soot produced during combustion. Examples of transition metal oxides to be supported include chromium(III) oxide, iron(III) oxide, copper(III) oxide, and titanium(III) oxide. Among these, chromium(III) oxide is preferred because it reduces carbon monoxide (CO) in the gas generated by the thermal decomposition treatment and does not easily produce soot.

[0069] [Conveyor] The conveyor is used to continuously pyrolyze the solar cell modules mounted on the recovery net. The conveyor is installed to pass through the pre-chamber, pyrolysis furnace, and post-chamber (described later) in the direction of transport. This allows the solar cell modules to be pyrolyzed while they remain on the recovery net. The conveyor may be made of iron, for example, and its shape may include a mesh-like wire or slits extending at predetermined intervals between rods provided perpendicular to the direction of travel of the conveyor. Specifically, examples include wire net conveyors, wire mesh conveyors, and mesh screen conveyors.

[0070] <Solar Cell Module Recycling Processing Method> As shown in Figures 3 to 4, the solar cell module recycling processing method according to one embodiment of the present invention comprises a pyrolysis step in which the solar cell module is pyrolyzed in a pyrolysis furnace in the solar cell module recycling system described above, a transport step in which the solar cell module mounted on the recovery network is transported together with the recovery network after the pyrolysis step, a valuable materials recovery step in which valuable materials are recovered from the pyrolyzed solar cell module after the transport step, and an exhaust gas treatment step for treating the gas generated in the pyrolysis furnace.

[0071] A solar cell module recycling method according to one embodiment of the present invention preferably includes a loading step before the pyrolysis step, in which filters are stacked on a tray, a collection net is placed on the filters, and solar cell modules are placed on the collection net. This is because such a configuration makes it easier to suppress the generation of soot.

[0072] In the solar cell module recycling method according to one embodiment of the present invention, it is preferable that the thermal decomposition treatment is carried out under an oxidizing atmosphere. When the thermal decomposition treatment is carried out under an oxidizing atmosphere, the PET contained in the backsheet is more easily decomposed, and the generation of soot tends to be suppressed. In addition, inorganic powders such as titanium dioxide and calcium carbonate contained in the backsheet tend to remain less.

[0073] In the solar cell module recycling method according to one embodiment of the present invention, it is preferable that the valuable material is at least one selected from the group consisting of glass, ribbon wire, silicon, silver, copper, titanium oxide, and calcium carbonate. When a solar cell module is subjected to thermal decomposition treatment with the solar cell module recycling system described above, soot is less likely to adhere to the glass plate, and it tends to be easier to use as a valuable material. In addition, since the resin is completely thermally decomposed, no resin adheres to the ribbon wire contained in the cell, and it tends to be easier to recover as a valuable material.

[0074] Hereinafter, one embodiment of the present invention will be described in more detail based on examples and with reference to the drawings as appropriate, but the present invention is not limited in any way to these examples.

[0075] [Example 1] As shown in Figures 1 to 4, the frame 5 and terminal box 9 were removed from the solar cell module 2 in the frame removal zone 17, taking care not to damage the glass. Next, the solar cell module 2 was transported to the mounting zone 18. A recovery device 50, which had been pre-assembled with a first filter 42, a second filter 44, and a tray 46 stacked in that order, was waiting in the transport zone 18. On top of the recovery device 50, the recovery net 40 and the solar cell module 2 were stacked in that order, with the solar cell module 2 positioned on top, to form the workpiece 23. The workpiece 23 was kept warm at 150°C in a heat-insulating tank 61.

[0076] After maintaining the temperature, the material to be processed 23 was placed on a conveyor and transported in the order of the front chamber 22, the pyrolysis furnace 20, and the rear chamber 26, undergoing continuous pyrolysis treatment. To transport the material to be processed 23 from the front chamber 22 to the pyrolysis furnace 20, the front chamber entrance side opening / closing device 22a was opened to transport the material to the front chamber 22, and then the front chamber entrance side opening / closing device 22a was closed. The temperature of the front chamber was measured at the top of the front chamber and was 100°C. With the front chamber entrance side opening / closing device 22a closed, the front chamber exit side opening / closing device 22b was opened, and the material to be processed 23 was transported to the pyrolysis furnace 20. The entrance side opening / closing devices and exit side opening / closing devices used in the front and rear chambers were iron shutters that opened and closed vertically.

[0077] Details of the solar cell module, first filter, second filter, tray, temperature measurement device, and pyrolysis furnace are as follows: • Solar cell module 2 used was an Inter Action product type IA250PSCa (cell type: polycrystalline solar cell, size: 1,640 mm × 992 mm × 4 mm). Frame 5 was removed before the pyrolysis treatment.

[0078] - First filter: A ceramic filter (Seisen Filter Co., Ltd. FCF-2 (made of silicon carbide), 10 ppi, 400 mm x 300 mm x 30 mmt (porosity 87.8%)) was used as the first filter.

[0079] The second filter was prepared as follows: Wako primary chromium(III) oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was suspended in water and stirred, and the ceramic filter was immersed in the solution to perform a dip coating. The second filter was then dried at 450°C. The mass before coating was 1,480 g, and the mass after coating and drying was 1,790 g.

[0080] A 2,100 mm x 1,210 mm x 50 mm iron tray 46 with a grid was fabricated, and 21 ceramic filters (second filters) coated with chromium oxide were used to place a 2,100 mm x 1,200 mm x 30 mm thick second filter on the bottom layer. Above that, in the middle layer, 21 ceramic filters (first filters) measuring 400 mm x 300 mm x 30 mm thick were used to place a 2,100 mm x 1,200 mm x 30 mm thick first filter. A collection net was then placed on top of that, and finally, solar cell modules were installed with the backsheet 10 facing downwards.

[0081] - Temperature measurement: The temperature was measured at the inlet side of the pyrolysis furnace, the central part of the pyrolysis furnace (Figure 3, 25), and the outlet side of the pyrolysis furnace. The temperature history of Example 1 is shown in Figure 5. In addition, a thermocouple thermometer was inserted in advance into the upper center of the first filter 42 in the middle section to measure the temperature of the material to be processed 23.

[0082] - Pyrolysis Furnace The pyrolysis furnace used a gas furnace (hot air circulation type heat treatment device: tact feed chain blow type furnace length 5,400 mm, furnace width 2,300 mm, furnace height 280 mm) as the heating device. A metallic burner MJPE-200K was used in the gas burner section 21, and a mixture of LP gas and air was burned to heat it. The heated mixture gas was fed by an Adachi Kiko "6.0-LF limit load fan" (450 m ３ The gas was supplied from the bottom of the pyrolysis furnace 20 through a slit at a rate of 2.0 kPa / min and 30 kW, and forcefully blown onto the second filter to enable heat exchange, while a portion of the circulated heated gas was exhausted.

[0083] As shown in Figure 3, in the pyrolysis furnace 20, a chain conveyor 29 moved from the inlet side 20a to the outlet side 20b, and the pyrolysis process was carried out by feeding the material through three sections: the heating section 27a, the combustion section 27b, and the cooling section 27c within the furnace. In the pyrolysis process, 21 solar cell modules 2 were pyrolyzed continuously. In the heating section 27a, the material was held for 5 minutes before feeding. In the combustion section, the temperature of the material to be processed 23 was measured, and the material was held without feeding until the temperature of the material to be processed 23 exceeded 550°C and then fell below 550°C. In the combustion section, the material was held for a total of 10 minutes before feeding. In the cooling section 27c, the material was held for 5 minutes before feeding. The pyrolysis process in the pyrolysis furnace 20 was carried out for a total of 20 minutes.

[0084] The pyrolysis treatment was carried out under an oxidizing atmosphere. During the pyrolysis treatment, the proportion of air in the supplied mixed gas was adjusted so that the oxygen concentration in the combustion section 27b was in the range of 6 vol% to less than 15 vol%, as measured by the oxygen concentration measuring unit 28. The heating temperature and supply amount of the supplied mixed gas were also adjusted so that the temperature of the workpiece 23 in the combustion section 27b was 470°C or higher.

[0085] After the thermal decomposition treatment, the solar cell module 24 to be thermally decomposed was transported to the rear chamber 26. During transport to the rear chamber, the rear chamber exit side opening / closing device 26b was closed, and the rear chamber inlet side opening / closing device 26a was opened to transport the module to the rear chamber 26. The temperature of the rear chamber was measured at the top of the rear chamber and was 200°C.

[0086] Furthermore, gas was collected from the front chamber suction port 22c and the rear chamber suction port 26c by an induced draft fan and supplied to the collection unit 80. The exhaust volume of the induced draft fan was 5.1 m³ in the front chamber. ３ / minutes, rear chamber is 4.3m ３ It was / minutes.

[0087] Depending on the heating equipment of the pyrolysis furnace 20, a portion of the gas collected in the collection unit 80 was supplied back to the gas burner unit 21. In addition, a portion of the collected gas was burned in the augmenter 82, which constitutes the exhaust gas processing unit 90, and then, after removing harmful substances by passing through the heat exchange unit 84, dust collection unit 86, and hydrogen fluoride removal unit 88, it was discharged to the outside via the chimney.

[0088] As shown in Figure 4, the pyrolysis-resistant solar cell module 24 was transported to the recovery zone 19 and then transported to the module recovery conveyor 30 by a lift 57 using the suspension section 58 of the recovery net 40. The valuable glass plates 6 were recovered without breaking by sliding them onto the glass recovery conveyor 32. The recovered glass plates 6 were washed in a glass cleaning device 74 to remove residues such as cells 4, ribbon wires 14, inorganic powders (silicon, silver, copper, titanium oxide, calcium carbonate) 7, and sealing fillers 8.

[0089] The valuable materials, Cell 4, Ribbon Wire 14, and Inorganic Powder 7, fell from the module recovery conveyor 30 and were recovered in the valuable materials recovery section 33. The Cell 4, Ribbon Wire 14, and Inorganic Powder 7 recovered in the valuable materials recovery section 33 were transported to the sorting machine 71 by the valuable materials conveyor 67, where they were separated into Cell 4, Ribbon Wire 14, and Inorganic Powder 7.

[0090] Furthermore, no soot was observed on the bottom ceramic filter, which was used as the second filter.

[0091] As shown in Figure 4, in the recovery zone 19, the solar cell modules 24 to be pyrolyzed were transported together with the recovery net 40, and the remaining recovery equipment 50, stacked in the order of the first filter 42, second filter 44, and tray 46, was transported to the mounting zone 18. The recovery equipment 50 was left waiting in the mounting zone 18 to stack more solar cell modules 2 to be pyrolyzed again.

[0092] As described above, using the solar cell module recycling system, we were able to prevent the leakage of gas and smoke generated during the pyrolysis process to the outside. The absence of gas and smoke leakage was confirmed visually. By providing a front chamber on the inlet side and a rear chamber on the outlet side of the pyrolysis furnace, it was possible to maintain a closed state between the inlet and outlet sides of the pyrolysis furnace. Furthermore, by providing suction ports in the front and rear chambers and supplying gas to the collection unit from these ports, it was possible to prevent the leakage of gas and smoke to the outside due to the opening and closing of the pyrolysis furnace. In addition, by keeping the front and rear chambers heated, it was possible to conserve fuel and perform continuous pyrolysis processing.

[0093] Furthermore, as described above, in the combustion section during the pyrolysis process, the temperature of the material being processed was held without cycle feeding until it dropped below 550°C, resulting in almost no smoke being generated when the pyrolysis furnace was opened and closed. This prevented the leakage of gases and smoke generated during the pyrolysis process of the material being processed to the outside.

[0094] Furthermore, the recovery equipment, including the second filter, the first filter, and the tray, which showed no soot buildup, can be loaded with solar modules again and transported to the pyrolysis furnace, thus improving thermal efficiency.

[0095] [Example 2] The three sections of the pyrolysis furnace—the heating section, the combustion section, and the cooling section—were each held for 4.5 minutes during the cycle feed, and the pyrolysis treatment was performed in the pyrolysis furnace for a total of 13.5 minutes. The exhaust volume of the induced draft fans in the pre-chamber and post-chamber was 60 m³. ３Except for the change in the rate per minute, the pyrolysis treatment was carried out in the same manner as in Example 1, and valuable materials were recovered. As a result, it was possible to prevent the leakage of gas and smoke generated during the pyrolysis treatment to the outside. The absence of leakage of gas and smoke to the outside was confirmed by visual inspection. In the combustion section during the pyrolysis treatment, the temperature was held for 4.5 minutes regardless of the temperature of the material to be treated, so the pyrolysis reaction of the resin, etc., had not yet finished and reacted with the oxygen that flowed in when the pyrolysis furnace was opened and closed, generating smoke. The generated smoke flowed into the front and rear chambers. By increasing the exhaust volume of the induced draft fans in the front and rear chambers compared to Example 1, a large amount of smoke flowing into the front and rear chambers could be collected from the suction port, and the leakage of smoke to the outside could be suppressed. Because the energy required increased due to the increased exhaust volume of the induced draft fans, the fuel efficiency was worse compared to Example 1.

[0096] [Comparative Example 1] Except that no suction ports were provided in the front and rear chambers, no gas was collected from the front and rear chambers, and the three sections of the pyrolysis furnace—the heating section, combustion section, and cooling section—were each held for 4.5 minutes during the cycle feed, and the pyrolysis treatment was performed in the pyrolysis furnace for a total of 13.5 minutes, the same as in Example 1, and valuable materials were recovered. As a result, outside air flowed into the pyrolysis furnace when the pyrolysis furnace was opened and closed, generating a large amount of smoke. The generated smoke leaked to the outside when the material to be treated was removed from the outlet side of the rear chamber. The leakage of smoke was confirmed by visual inspection. It was found that simply providing a front and rear chamber is insufficient to prevent smoke from leaking to the outside.

[0097] Table 1 below shows the weight of the solar cell module and its frame used in Example 1 before thermal decomposition treatment, as well as the weight of the glass plate, cells, ribbon wires, and terminal boxes recovered after thermal decomposition treatment.

[0098] 2: Solar cell module 4: Cell 5: Frame 6: Glass plate 7: Inorganic powder (silicon, silver, copper, titanium oxide, calcium carbonate) 8: Sealing filler 9: Terminal box 10: Backsheet 14: Ribbon wire 16: Recycling system 17: Frame removal zone 18: Mounting zone 19: Recovery zone 20: Pyrolysis furnace 20a: Pyrolysis furnace inlet side 20b: Pyrolysis furnace outlet side 21: Gas burner section 22: Front chamber 22a: Front chamber inlet side opening / closing mechanism 22b: Front chamber outlet side opening / closing mechanism 22c: Front chamber suction port 23: Material to be processed 24: Solar cell module to be pyrolyzed 25: Temperature measurement section 26: Rear chamber 26a: Rear chamber inlet side opening / closing mechanism 26b: Rear chamber outlet side opening / closing mechanism 26c: Rear chamber suction port 27a: Heating section 27b: Combustion section 27c: Cooling section 28: Oxygen concentration measurement unit 29: Chain conveyor 30: Module recovery conveyor 32: Glass recovery conveyor 33: Valuable material recovery unit 40: Recovery net 42: First filter 44: Second filter 46: Tray 50: Recovery equipment 57: Lift 58: Suspended unit 61: Insulated tank 67: Conveyor for valuable materials 71: Sorting machine 74: Glass cleaning device 80: Collection unit 82: Augmenter 84: Heat exchange unit 86: Dust collection unit 88: Hydrogen fluoride removal unit 90: Exhaust gas processing unit

Claims

1. A solar cell module recycling system for continuously pyrolytically decomposing solar cell modules mounted on a collection network by placing them on a conveyor, comprising: a pyrolysis furnace for pyrolytically decomposing the solar cell modules mounted on the collection network; a front chamber on the inlet side of the pyrolysis furnace; a rear chamber on the outlet side of the pyrolysis furnace; a collection unit for collecting gas generated in the pyrolysis furnace; and an exhaust gas processing unit for processing the gas collected in the collection unit, wherein the conveyor is provided to penetrate the front chamber, the pyrolysis furnace, and the rear chamber in the transport direction, and has suction ports in the front chamber and the rear chamber, and supplies the gas collected from the suction ports to the collection unit.

2. The solar cell module recycling system according to claim 1, wherein the exhaust gas processing unit has at least an augmenter.

3. The solar cell module recycling system according to claim 1, wherein the suction port is located on the top surface of the front chamber and the rear chamber.

4. The solar cell module recycling system according to claim 1, wherein the gas collected from the suction port is outside air in addition to the gas and / or smoke generated in the pyrolysis furnace.

5. A solar cell module recycling method comprising: a pyrolysis step of pyrolysis a solar cell module in a pyrolysis furnace according to any one of claims 1 to 4; a transport step of transporting the solar cell modules mounted on a collection network together with the collection network after the pyrolysis step; a valuable materials recovery step of recovering valuable materials from the pyrolysis-treated solar cell modules after the transport step; and an exhaust gas treatment step of treating the gas generated in the pyrolysis furnace.

6. The solar cell module recycling method according to claim 5, further comprising a loading step of stacking filters on a tray, loading a recovery net on the filters, and loading solar cell modules on the recovery net, prior to the pyrolysis step.

7. The solar cell module recycling method according to claim 5, wherein the thermal decomposition treatment is carried out under an oxidizing atmosphere.

8. The solar cell module recycling method according to claim 5, wherein the valuable material is at least one selected from the group consisting of glass, ribbon wire, silicon, silver, copper, titanium oxide, and calcium carbonate.

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