Pyrolysis equipment for composite materials and recycling method thereof

Abstract

The present invention relates to a method and an apparatus for pyrolyzing composite materials for recycling. The method and the apparatus comprise a first rotary cylindrical kiln (1) configured to receive a composite material charge through its inlet opening, and a second rotary cylindrical kiln (4) suitable for continuously receiving the composite material charge from the first kiln (1) without interruption and configured to maintain an atmosphere with a controlled oxygen concentration between 2% and 20% and heat to a temperature between 200°C and 600°C. The first kiln (1) comprises an internal spiral (2) with an open structure in its central portion, and the first kiln (1) is sealed and configured to maintain a controlled oxygen atmosphere during operation with an oxygen concentration between 2% and 8% and heat to a temperature between 200°C and 600°C.

Description

Detailed Description of the Invention

[0001] [Object of the Invention] The present invention can be included in the technical field of pyrolysis equipment and / or methods for composite materials with the aim of recycling and recovering them in as close a state as possible to their original state for reuse. More specifically, the object of the present invention relates to an apparatus and a continuous method utilizing two closed reactors with a controlled atmosphere in the presence of oxygen, the amount of which exhibits an increasing gradient ratio, allowing for the proper separation of the fibers and the correct industrialization of the process, in order to guarantee the recycling of composite materials present, for example, in the wind and aviation sectors.

[0002] BACKGROUND OF THE INVENTION Recycling of composite materials is a fundamental goal in the art, since on the one hand the use of composite materials is increasing exponentially due to their excellent properties and behavior, and on the other hand the high energy consumption required, resulting in large amounts of CO2 emissions during their production. The processes known in the art, which account for the complete absence of oxygen in pyrolysis, do not separate the fibers of the composite material in an optimal way and / or in a quality suitable for reuse in a similar quality to the original composite.

[0003] These batch processes cannot be fully industrialized and scaled up due to the constant door opening and closing with associated heat losses, and also require inert gas injection into each batch to reduce oxygen levels, resulting in high consumption of insulating gas.

[0004] Furthermore, some known continuously operated furnaces are open type with a belt for transporting the material, which has the additional disadvantage of requiring the constant injection of a shielding gas to maintain a low O2 concentration to avoid combustion. US2019039266A1 discloses a pyrolysis plant and process for recovering (recycling) carbon fibers from plastics containing carbon fibers, in particular carbon fiber reinforced plastics (CFPs or CFP materials), preferably plastics containing carbon fibers, and / or carbon fiber reinforced composite materials (composites).

[0005] DESCRIPTION OF THE INVENTION The present invention aims to solve some of the problems mentioned in the art. More specifically, a first aspect of the present invention relates to a composite material pyrolysis facility for recycling composite materials. The facility comprises a first rotary cylindrical kiln configured to receive a composite material input through its inlet opening, and a second rotary cylindrical kiln. The first kiln has an inner spiral with an open structure in a central portion thereof for the movement of the composite material and the passage of gases resulting from pyrolysis. The first kiln is sealed and configured to maintain a controlled oxygen atmosphere during operation between 2% and 8% oxygen and to heat to a temperature between 200°C and 600°C. The second sealed kiln is suitable for continuously receiving a composite material input that has passed through the first kiln without interruption and is further configured to maintain an atmosphere with a controlled oxygen concentration between 2% and 20% and to heat to a temperature between 200°C and 600°C. Preferably, the second kiln is configured to maintain a controlled oxygen atmosphere in the range of between 8% and 14% oxygen.

[0006] The above solution allows for the recycling of composite materials with more than one type of reinforcement, separating not only the matrix but also the different types of reinforcement, the latter of which are very common in products such as wind turbine blades, automotive and aeronautical components, and sporting goods.

[0007] A composite material suitable for loading into the described installation is understood to be any material composed of a matrix, which may be cured or uncured, for example, of a thermosetting or thermoplastic material and one or more bonded reinforcements, such as glass fibers, carbon fibers, minerals, natural fibers, ceramics, metals, etc.

[0008] The continuous nature of the process allows for better industrialization and process scalability, which is much needed given the large volume of materials currently on the market. This continuous process not only maintains the quality of the final product, but also reduces heating energy consumption because, unlike batch processes, there is no constant door opening and closing, which entails heat loss and heating of the material container in batch processes. It also consumes less insulating gas because there is no need to inject inert gas into each batch to reduce O2 concentration.

[0009] The installation and operation, based on the above solution, allows for continuous pyrolysis, with the feed entering the first furnace in an oxidizing atmosphere in a gradient section and passing continuously through a different atmosphere to the second furnace without interruption, which has been shown to improve throughput, process scalability, productivity, and end-product recycling quality.

[0010] The open spiral of the first furnace facilitates the passage of gases resulting from the pyrolysis of the matrix, which can be collected at the top of the furnace for discharge outside the furnace and condensed, for example, by a fractional condensation gas extraction column located adjacent to the material inlet opening of the first furnace.

[0011] The first furnace may have a downward slope at an angle α to facilitate gas flow from pyrolysis toward its top. This allows the hottest gases to circulate toward the composite material input zone. The downward slope of the first furnace may have an angle α of up to 45°, preferably between 10 and 20°. Alternatively, this may be 0°, resulting in the first furnace having a horizontal configuration. Similarly, the rotation speed of the first furnace may be between 0.01 and 5 rpm.

[0012] To feed the composite material charge intended to be recycled, the facility will be equipped with a semi-open screw feeder in the first section to organize the charge before it enters the first furnace.

[0013] To ensure that the O2 parameters are within the ranges mentioned above, the installation may include oxygen sensors at the gas inlet and outlet of the first furnace, since the furnace is sealed and does not allow for other oxygen inlets.

[0014] At the end of the first furnace, the composite material charge is transferred to a second rotating cylindrical furnace. In a preferred embodiment, the same furnace has an upward inclination at a positive angle β. Preferably, the angle β is up to 45°, preferably between 0° and 10°. Alternatively, if the second furnace is in a horizontal position, the angle may be 0°.

[0015] This configuration allows the composite material to reform after the volume of the material is reduced by half and the rotational speed of the furnace is reduced by half to a rotational speed of between 0.01 and 3 rpm, more preferably between 0.01 and 2 rpm, after which most of the matrix that formed the composite material is lost.

[0016] It should be noted that in this second furnace, the reinforcements are partially oxidized in this zone in an atmosphere of between 8% and 20% O2 and at temperatures between 200° and 600° C. These operating conditions of the second furnace ensure the oxidation necessary to separate the glass fiber filaments from the carbon fibers, if necessary, for composites containing these reinforcements or other reinforcements associated with them.

[0017] To achieve the required atmosphere in this second furnace, it is preferable to circulate a mixed gas flow with the required O2 concentration. To ensure this is appropriate, measurements are taken on the mixed gas before it is injected into the furnace, and an O2 sensor is installed at the gas outlet of this second furnace to control oxidation and determine the amount reacted inside. If the O2 concentration is low, this output gas is mixed with the input gas to optimize the mixture.

[0018] If it is necessary to improve the quality by separating these fibers individually, the installation can further include a glass fiber and carbon fiber filament separator at the outlet of this second furnace to allow the different fibers obtained to be reused. This separator is only used for composites containing two or more reinforcing fibers. In the case of composites reinforced with glass fiber and carbon fiber, this separation can be carried out using electrostatic charge and / or density devices included in the described installation.

[0019] The separated glass and carbon fibers can then be conveyed to an application zone for the application of a sizing solution that impregnates the interfacial material. This impregnation improves the handling of the fibers and their use in new composite materials. Thus, the reinforcement is completely freed of any matrix residue and impregnated with new sizing, allowing for handling and further processing.

[0020] A second aspect of the present invention relates to a method for the pyrolysis of composite materials for recycling, comprising the steps of: providing a first rotating cylindrical furnace with an inlet opening; introducing a composite material charge into the first furnace through the inlet opening; introducing an oxygen-containing gas stream into the first furnace until a controlled oxygen atmosphere of 2 to 8% is reached inside the first furnace; heating the first furnace to a temperature between 200° and 600°C; extracting gases resulting from pyrolysis through an extraction column; providing a second rotating cylindrical furnace; continuously and uninterruptedly conveying the composite material charge at the outlet of the first furnace to the second furnace; introducing an oxygen-containing gas stream into the first furnace until a controlled oxygen atmosphere of 10 to 20% is reached inside the first furnace; and heating the second furnace to a temperature between 200° and 600°C, wherein the first furnace has an internal spiral with an open structure in a central portion of the internal spiral for the movement of the composite material and the passage of gases resulting from pyrolysis. The composite material charge may be introduced by an endless screw feeder.

[0021] Similarly, the flow rate of the oxygen-containing gas can be controlled within the endless screw feeder. Specifically, the oxygen concentration in the screw feeder is measured before entering the first furnace and the flow rate required to achieve the aforementioned concentration is determined.

[0022] In a preferred embodiment, the method includes tilting the first furnace at a downward angle relative to the horizontal during installation. Preferably, the method includes tilting the first furnace at a downward angle α between 0° and 45°. Similarly, the method may further include tilting the second furnace upward from the horizontal during installation. Preferably, the method includes tilting the second furnace at an upward angle β between 0° and 45°. Preferably, during operation, the first furnace rotates at a speed of 0.01 to 5 rpm. Similarly, the method may include rotating the second furnace at a rotational speed of 0.01 to 3 rpm.

[0023] To ensure the required atmosphere in each reactor, the process may include measuring the oxygen concentration at the gas outlet of the first furnace and / or the second furnace, and mixing the gas outlet of the second furnace with the gas inlet of the corresponding furnace if the measured oxygen concentration is below a predetermined oxidation threshold contained in the input.

[0024] DESCRIPTION OF THE DRAWINGS As a supplement to the description given herein, and with a view to making the features of the invention more readily comprehensible, based on preferred practical exemplary embodiments thereof, said description is accompanied by a set of drawings which form an integral part thereof and which show, by way of illustration and not by way of limitation, the following: FIG. 1 is a schematic diagram of a preferred embodiment of the apparatus showing a first furnace with a downward slope, a second furnace with an upward slope, a screw feeder, and an impregnation zone with sizing.

[0025] Preferred Embodiments of the Present Invention A detailed description of preferred exemplary embodiments of the present invention is provided below with reference to the accompanying drawings mentioned above.

[0026] As shown in Figure 1, the present invention relates to an installation for the pyrolysis of recycled composite materials. The pyrolysis installation comprises a first rotating cylindrical kiln (1) configured to receive a composite material feed through its inlet opening, a gas extraction column (3) positioned adjacent to the inlet opening of the first kiln (1), and a second rotating cylindrical kiln (4), the first kiln (1) having an internal spiral (2) with an open structure in its central part for the passage of the composite material and gas resulting from the pyrolysis, the first kiln (1) being sealed and configured to maintain a controlled oxygen atmosphere during operation with an oxygen concentration between 2% and 8% and to heat to a temperature between 200°C and 600°C, and the second kiln (4) is suitable for continuously receiving the composite material feed that has passed through the first kiln (1) without interruption and is further configured to maintain an atmosphere with a controlled oxygen concentration between 10% and 20% and to heat to a temperature between 200°C and 600°C.

[0027] Similarly, in the preferred embodiment of Figure 1, the first furnace (1) has a downward slope with a downward angle (α) and the second furnace (2) has an upward slope with an upward angle (β).

[0028] The second furnace (4) may be equipped with a column (9) for extracting gases from the second furnace that cause pyrolysis. This extraction column (9) may be located at or adjacent to the outlet of the second rotary cylindrical furnace (4).

[0029] Furthermore, for feeding and organizing the input, according to the described preferred embodiment, the installation comprises a screw feeder (5) located adjacent to the inlet opening of the first furnace (1) for organizing the input of composite material before it enters the first furnace.

[0030] For the input of the composite material, the installation can comprise a first hopper (6), and for the transport of the composite material from the first furnace (1) to the second furnace (4), the installation can comprise a second hopper (7) and a second screw feeder (8).

[0031] Another aspect of the present invention relates to a method for pyrolysis of composite materials for recycling, said pyrolysis method comprising the steps of: providing a first rotating cylindrical kiln (1) with an inlet opening therein; introducing a composite material charge into said first kiln (1) through said inlet opening; introducing an oxygen-containing gas stream into said first kiln (1) until a controlled oxygen atmosphere of 2 to 8% is reached inside said first kiln (1); heating said first kiln (1) to a temperature between 200° and 600°C; extracting gases resulting from pyrolysis through an extraction column (3); providing a second rotating cylindrical kiln (4); and heating said first kiln (1) to a temperature between 200° and 600°C. the step of continuously and without interruption conveying the charge of composite material at the outlet of the first furnace (1) to the second furnace (4), the step of introducing an oxygen-containing gas stream into the second furnace (4) until a controlled oxygen atmosphere of 10 to 20% is reached inside the second furnace (4), and the step of heating the second furnace (4) to a temperature between 200° and 600°C, wherein the first furnace (1) comprises an internal spiral (2) with an open structure in the central part of the internal spiral (2) for the movement of the composite material and the passage of gases resulting from the pyrolysis.

[0032] To ensure and control the oxygen atmosphere in each furnace (1, 4), the method may include measuring the oxygen concentration at the gas outlet of each furnace (1, 4), measuring the oxygen concentration in the screw feeder (5), and, if the measured oxygen concentration is below the oxidation threshold of each furnace (4), mixing the gas outlet with the gas inlet of the corresponding furnace (4). Similarly, during operation, the method in one embodiment may include rotating the first furnace at a rotation speed comprised between 0.01 and 5 rpm. Similarly, during operation, the method may include rotating the second furnace (4) at a speed comprised between 0.01 and 2 rpm with the composite material charge present. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 1 is a schematic diagram of a preferred embodiment of the apparatus showing an impregnation zone with a downwardly sloping first furnace, an upwardly sloping second furnace, a screw feeder, and sizing.

Claims

1. A pyrolysis facility for composite materials to be recycled, comprising: a first rotary cylindrical furnace (1) configured to receive a charge of composite material through an inlet opening thereof; a gas extraction column (3) located adjacent to the inlet opening of the first furnace (1); a second rotary cylindrical furnace (4), the first furnace (1) comprises an internal spiral (2) with an open structure in its central part for the movement of the composite material and the passage of gases resulting from pyrolysis; the first furnace (1) is sealed and configured to maintain a controlled oxygen atmosphere during operation with an oxygen concentration between 2% and 8% and to heat to a temperature between 200° and 600°C; The second furnace (4) is adapted to continuously receive, without interruption, a charge of composite material passed through the first furnace (1), and is further adapted to maintain an atmosphere with a controlled oxygen concentration between 2% and 20% and to heat to a temperature between 200°C and 600°C.

2. 2. The installation according to claim 1, wherein the first furnace (1) has a downward slope.

3. 3. The installation according to claim 2, wherein the downward slope is at an angle (α) between 10 and 20°.

4. 3. The installation according to claim 1 or 2, wherein the second furnace (4) has an upward slope.

5. 5. The installation according to claim 4, wherein the upward slope is at an angle (β) between 0 and 10°.

6. 2. The installation according to claim 1, wherein the first furnace (1) is configured to rotate at a rotational speed between 0.01 and 5 rpm.

7. 2. The installation according to claim 1, wherein the second furnace (4) is configured to rotate at a rotational speed between 0.01 and 2 rpm.

8. The first furnace (1) comprises: one or more first injection elements configured to inject a gas stream comprising oxygen into said first furnace (1); one or more first oxygen sensors arranged at the gas outlet of the extraction column (3) and at the feeder (5) of the first furnace (1), said sensors measuring the oxygen concentration at the inlet and outlet of the first furnace (1); 10. The facility of claim 1, further comprising: a control module coupled to the injection element and the sensor to adjust the gas flow input based on the oxygen concentration measured by the sensor.

9. The second furnace (4) is one or more second injection elements configured to inject a gas stream containing oxygen into said second furnace (4); one or more second oxygen sensors arranged at the gas outlet of the second furnace (4), said sensors measuring the oxygen concentration at the outlet of the second furnace (4); 9. The installation according to any one of claims 1 to 8, further comprising a second gas mixing element configured to mix a gas outlet from the second furnace (4) with a gas inlet provided by the injection element when the measured oxygen concentration is below an oxidation threshold in the second furnace (4).

10. 2. The installation according to claim 1, including an endless screw type feeder (5) located adjacent the inlet opening of the first furnace (1) for organizing the charge of composite material before it enters the first furnace (1).

11. 2. The installation according to claim 1, further comprising a glass fiber and / or carbon fiber filament separator arranged after the second furnace (4).

12. 12. The installation according to claim 11, comprising a sizing zone (10) comprising a distribution device for a sizing solution for impregnating the separated fibers.

13. providing a first rotary cylindrical furnace (1) with an inlet opening therein; introducing a charge of composite material into said first furnace (1) through said inlet opening thereof; introducing a gas flow containing oxygen into the first furnace (1) until a controlled oxygen atmosphere of 2 to 8% is reached inside the first furnace (1); heating the first furnace (1) to a temperature between 200° and 600°C; Extracting the gas resulting from the pyrolysis through an extraction column (3); Providing a second rotary cylindrical furnace (4); conveying the charge of composite material at the outlet of the first furnace (1) continuously and without interruption to the second furnace (4); introducing a gas flow containing oxygen into the first furnace (1) until a controlled oxygen atmosphere of 10 to 20% is reached inside the first furnace (1); and heating the second furnace (4) to a temperature between 200° and 600°C; the first furnace (1) comprises an internal spiral (2) with an open structure in its central part for the movement of the composite material and the passage of gases resulting from pyrolysis; A method for pyrolysis of composite materials for recycling.

14. 14. The method according to claim 13, further comprising the step of tilting the first furnace (1) at a downward angle (α) relative to the horizontal.

15. 14. The method of claim 13, further comprising tilting the second furnace (4) at an upward angle (β) from the horizontal.

16. 14. The method according to claim 13, comprising the step of rotating the first furnace (1) during operation at a rotational speed of 0.01 to 5 rpm.

17. 14. The method according to claim 13, comprising the step of rotating the second furnace (4) at a rotational speed of 0.01 to 2 rpm during operation.

18. measuring the oxygen concentration at the gas outlet of the first furnace (1) and at the inlet of a feeder (5) that supplies composite material to the first furnace (1); and controlling the oxygen concentration in the first furnace (1) by injecting a flow rate of exhaust gas from the furnaces (1, 4), 14. The method according to claim 13, wherein the flow rate is determined by a function including the data measured by sensors both in the feeder (5) and at the outlet of the first furnace (1).

19. measuring the oxygen concentration at the gas outlet of the second furnace (4); and mixing the gas outlet from the second furnace (4) with the gas inlet to the second furnace (4) if the measured oxygen concentration is below a predetermined oxidation threshold of the second furnace (4).

Images