JP2024056374A - Fiber-reinforced plastic recycling device and fiber-reinforced plastic recycling method - Google Patents

Abstract

The present invention provides a fiber-reinforced plastic recycling device and a fiber-reinforced plastic recycling method that can improve the uniformity and thermal efficiency of heat treatment in recycling fiber-reinforced plastic.
[Solution] An apparatus having a processing furnace 1 in which fiber reinforced plastic P is contained and heated, a heating port 3 provided at a position lower than half the total height of the interior of the processing furnace 1 and supplying thermal energy for heating the interior of the processing furnace 1, and an exhaust port 4 provided at a position lower than half the total height of the interior of the processing furnace 1 and exhausting gas inside the processing furnace 1 generated as a result of the heating, or a method in which fiber reinforced plastic P is contained inside the processing furnace 1, thermal energy is supplied to heat the interior of the processing furnace 1 from a position lower than half the total height of the interior of the processing furnace 1, and gas inside the processing furnace 1 generated as a result of the heating of the fiber reinforced plastic P is exhausted from a position lower than half the total height of the processing furnace 1.
[Selected figure] Figure 2

Description

This invention relates to a fiber-reinforced plastic recycling device and method for recovering fibers, such as glass fibers and carbon fibers, contained in fiber-reinforced plastic.

A known method for recycling fibers (such as glass fibers or carbon fibers) contained in fiber-reinforced plastics is to heat the fiber-reinforced plastic to about 300 to 400°C to pyrolyze the resin, and then to oxidize and remove the resin remaining in the fibers as carbon by heating the plastic to 500°C or higher while supplying oxygen.

As devices for carrying out this heat treatment, those shown in the following Patent Documents 1 and 2 have been proposed, for example. In the device described in Patent Document 1, a fiber-reinforced plastic is placed in the furnace chamber 1' of a dry distillation furnace 1 heated by a fire box 2, and heat treatment is carried out. The decomposition gas of the resin generated by this heat treatment is sent to the outside of the furnace chamber 1' from a gas delivery pipe 3 installed in the ceiling wall of the furnace chamber 1' (see columns 2, lines 10 to 18, Figure 1, etc. of Patent Document 1).

In addition, in the device described in Patent Document 2, a fiber-reinforced plastic is provided in the heating section 31 in the gasification furnace 1 to carry out heat treatment. The decomposition gas of the resin generated by this heat treatment is sent to the combustion furnace 2 from the gas outlet 22 provided in the ceiling wall of the gasification furnace 1, where it is oxidized and burned (see paragraphs 0013-0024, Figure 1, etc. of Patent Document 2).

Japanese Patent Publication No. 55-6804 Japanese Patent Application Laid-Open No. 7-305078

In the apparatus shown in Patent Document 1 and Patent Document 2, as shown in a schematic front view in FIG. 5, the ceiling wall of the treatment furnace 100 (corresponding to the carbonization furnace 1 and gasification furnace 1 in Patent Documents 1 and 2; the same applies below) that performs heat treatment of fiber-reinforced plastic P is provided with an exhaust port 101 (gas delivery pipe 3, gas outlet 22) for discharging decomposition gas, so that the light gas in a high temperature state that is sent into the treatment furnace 100 (carbonization furnace 1, gasification furnace 1) from the heating port 102 is likely to accumulate at the top of the treatment furnace 100 (carbonization furnace 1, gasification furnace 1) and then be discharged directly from the exhaust port 101 (gas delivery pipe 3, gas outlet 22) (see arrow f' in FIG. 5). This causes a temperature unevenness in which the temperature inside the upper part of the treatment furnace 100 (carbonization furnace 1, gasification furnace 1) is relatively higher than the temperature inside the lower part, resulting in a problem of uneven heat treatment of the fiber-reinforced plastic P. In addition, high-temperature gas with a large amount of thermal energy is likely to be discharged directly from the exhaust port 101 (gas delivery pipe 3, gas outlet port 22), which reduces thermal efficiency and increases fuel costs.

Therefore, the objective of this invention is to improve the uniformity and thermal efficiency of heat treatment in the recycling of fiber-reinforced plastics.

In order to solve the above problems, the present invention provides:
A fiber-reinforced plastic recycling device that heats fiber-reinforced plastic to recover fibers contained in the fiber-reinforced plastic,
a treatment furnace for accommodating and heating the fiber reinforced plastic therein;
a heating port provided at a position lower than half of the total height of the inside of the processing furnace and supplying thermal energy for heating the inside of the processing furnace;
an exhaust port provided at a position lower than half of the total height inside the processing furnace, for exhausting gas inside the processing furnace generated as a result of the heating;
The present invention provides a fiber-reinforced plastic recycling device having the above features.

In this way, the thermal energy (e.g., high-temperature furnace atmosphere gas heated by a burner) supplied from a heating port installed at a low position inside the treatment furnace causes the decomposition of the fiber-reinforced plastic upward. Furthermore, the excess thermal energy (e.g., relatively high-temperature furnace atmosphere gas) flows downward from the top of the treatment furnace together with the decomposition gas of the fiber-reinforced plastic, and the excess thermal energy further promotes the decomposition of the fiber-reinforced plastic. The up and down movement of this thermal energy (high temperature or relatively high temperature furnace atmosphere gas) tends to increase the temperature in the lower part of the furnace, which tends to be relatively low, and the temperature unevenness in the furnace is reduced, making the heat treatment uniform. Furthermore, as the thermal energy moves up and down, this thermal energy is used without waste during the thermal decomposition of the fiber-reinforced plastic, ensuring high thermal efficiency.

In the recycling device according to the above configuration, the processing furnace can be configured to be provided with an oxygen supply port that supplies oxygen to the heating port side. In this way, the decomposition gas of the fiber reinforced plastic flowing downward inside the furnace is drawn into the heating port side by the ejector effect of the oxygen supplied (sprayed) from the oxygen supply port. Then, the thermal energy supplied from this heating port burns the mixed gas of the decomposition gas and oxygen, which can assist in heating the fiber reinforced plastic. This can improve the thermal efficiency of the heat treatment.

In a recycling device provided with the oxygen supply port, the angle of the oxygen supplied from the oxygen supply port can be set so that it is directed from the exhaust port side to the heating port side. In this way, the ejection effect of the decomposition gas can be strengthened to guide the decomposition gas to the oxygen supply port side, and the thermal efficiency of the heat treatment can be further improved.

In order to solve the above problems, the present invention provides:
A method for recycling fiber-reinforced plastics, comprising heating a fiber-reinforced plastic to recover fibers contained in the fiber-reinforced plastic,
The present invention provides a method for recycling fiber-reinforced plastics, which is characterized in that the fiber-reinforced plastics are placed inside a processing furnace, thermal energy is supplied to heat the inside of the processing furnace from a position lower than half the height of the total interior height of the processing furnace, and gas inside the processing furnace generated as a result of heating the fiber-reinforced plastics is exhausted from a position lower than half the height of the total interior height of the processing furnace.

In this way, similar to the above, the thermal energy supplied from a low position in the treatment furnace (e.g., high-temperature furnace atmosphere gas heated by a burner) moves upward to cause the decomposition of the fiber-reinforced plastic. Furthermore, surplus thermal energy (e.g., relatively high-temperature furnace atmosphere gas) moves downward from the top of the treatment furnace together with the decomposition gas of the fiber-reinforced plastic, and this surplus thermal energy further promotes the decomposition of the fiber-reinforced plastic. The up and down movement of this thermal energy (high-temperature furnace atmosphere gas) tends to increase the temperature in the lower part of the furnace, which tends to be relatively low, and the temperature unevenness in the furnace is reduced, making the heat treatment uniform. In addition, the thermal energy of the gas exhausted from a low position in the treatment furnace is used without waste during the thermal decomposition of the fiber-reinforced plastic, ensuring high thermal efficiency.

In the recycling method according to the above configuration, oxygen can be supplied into the treatment furnace together with the thermal energy to combust the decomposition gas of the fiber-reinforced plastic generated by heating the fiber-reinforced plastic, and the combustion heat from this combustion can be used to assist in heating the fiber-reinforced plastic. In this way, combustible decomposition gas is not wasted, and the thermal efficiency of the heat treatment can be improved.

In the recycling method in which oxygen is supplied into the treatment furnace, the temperature inside the treatment furnace can be controlled to be within the range of 500°C to 600°C by adjusting the amount of oxygen supplied. In this way, the temperature inside the treatment furnace can be easily adjusted to the above-mentioned temperature range suitable for the thermal decomposition of fiber-reinforced plastics.

In this invention, heat energy is supplied from a position lower than half the total height inside the treatment furnace, and gas inside the treatment furnace generated as a result of the heating is exhausted from a position lower than half the total height inside the treatment furnace, thereby improving the uniformity and thermal efficiency of the heat treatment when recycling fiber-reinforced plastics.

FIG. 1 is a perspective view showing a schematic diagram of one embodiment of a fiber-reinforced plastic recycling device according to the present invention; FIG. 2 is a front view of the recycling device shown in FIG. FIG. 2 is a plan view of the recycling device shown in FIG. FIG. 2 is a plan view showing a modified example of the recycling device shown in FIG. FIG. 1 is a front view showing a schematic diagram of a recycling device according to a conventional technique.

One embodiment of the fiber-reinforced plastic recycling device according to the present invention will be described with reference to the drawings. This recycling device A is a device for heating fiber-reinforced plastic P and recovering the fibers contained in the fiber-reinforced plastic P, and is equipped with a processing furnace 1 that contains and heats the fiber-reinforced plastic P, as shown in a perspective view in FIG. 1, a front view in FIG. 2, and a plan view in FIG. 3.

A heating port 3 is formed in the side wall of the treatment furnace 1, to which a heating source 2 for heating the interior of the treatment furnace 1 is attached. This heating port 3 is a through hole that penetrates the inside and outside of the side wall. The height of this heating port 3 is lower than half the total height of the interior of the treatment furnace 1, and is provided near the bottom of the treatment furnace 1. In this embodiment, a burner (hereinafter, given the same reference number as the heating source 2) is used as the heating source 2, and this burner 2 supplies thermal energy to the inside of the treatment furnace 1 for heat-treating the fiber-reinforced plastic P.

An exhaust port 4 is formed in the side wall of the processing furnace 1 to exhaust gas inside the processing furnace 1 that is generated as a result of heating. This exhaust port 4 is a through hole that penetrates the inside and outside of the side wall. The height of this exhaust port 4 is lower than half the total height of the inside of the processing furnace 1, and is provided near the bottom of the processing furnace 1. An exhaust pipe 5 is connected to the exhaust port 4.

In FIG. 2, the burner 2 and the exhaust pipe 5 are drawn slightly offset in height to make the drawing easier to see, but they may be the same height, or one may be higher than the other. When the processing furnace 1 has a rectangular horizontal cross section, the heating port 3 and the exhaust port 4 may be formed in any of the four side walls, but it is preferable to form them in the same side wall as in this embodiment.

Between the heating port 3 and the exhaust port 4, an oxygen supply port 6 is formed to supply oxygen to the heating port 3 side. This oxygen supply port 6 is a through hole that penetrates the inside and outside of the side wall. An oxygen supply pipe 7 is connected to the oxygen supply port 6. This oxygen supply pipe 7 is attached at an angle to the normal line of the side wall, and the angle of the oxygen supplied from the oxygen supply port 6 toward the inside of the processing furnace 1 is set so that it is jetted obliquely from the exhaust port 4 side to the heating port 3 side. The height of the oxygen supply port 6 is preferably about the same as that of the heating port 3. A gas containing oxygen, such as pure oxygen or air, is supplied from the oxygen supply pipe 7.

A secondary combustion furnace 8 is connected to the exhaust pipe 5. This secondary combustion furnace 8 is a furnace that further heats the exhaust passing through the exhaust pipe 5 to a high temperature of 800°C or higher to burn and remove unburned materials in the exhaust. The exhaust treated in this secondary combustion furnace 8 is released into the atmosphere through a discharge pipe 9.

The operation of the recycling device A will be described. This recycling device A is applicable to fiber-reinforced plastics P containing various fibers such as glass fibers and carbon fibers. First, the fiber-reinforced plastics P to be recycled are accommodated in the treatment furnace 1 using an installation jig such as a rack. Then, the flame of a burner 2 as a thermal energy source is ejected from a heating port 3 to heat the inside of the treatment furnace 1. The high-temperature furnace atmosphere gas, which has become lighter due to the heating, rises inside the treatment furnace 1 (see arrow _f1 in FIG. 2), and thermally decomposes the resin content of the fiber-reinforced plastics P.

Since no exhaust port for exhausting gas inside the treatment furnace 1 is formed in the upper part of the treatment furnace 1 (above half the height of the entire interior height of the treatment furnace 1), the rising high-temperature atmospheric gas inside the treatment furnace reverses direction at the upper part of the treatment furnace 1 and flows downward (see arrow _f1 in FIG. 2). The relatively high-temperature atmospheric gas inside the furnace having surplus thermal energy further promotes the decomposition of the fiber-reinforced plastic P.

The up and down movement of this thermal energy (high or relatively high temperature furnace atmosphere gas) tends to raise the temperature in the lower part of the furnace, which tends to be relatively low, and reduces temperature variations in the furnace temperature, making the heat treatment more uniform. In addition, as the thermal energy moves up and down, this thermal energy is used efficiently during the thermal decomposition of the fiber reinforced plastic P, ensuring high thermal efficiency. The furnace atmosphere gas, which has lost its thermal energy and become relatively low temperature, is exhausted from the exhaust port 4.

From the oxygen supply port 6, oxygen is injected (supplied) at an angle from the exhaust port 4 side to the heating port 3 side through the oxygen supply pipe 7. The injection speed is set to a high speed of about 10 to 20 m/sec, and the ejector effect accompanying this injection draws the decomposition gas of the fiber reinforced plastic P to the heating port 3 (burner 2) side (see arrow _f2 in FIG. 3). As a result, the injected oxygen burns the decomposition gas, and the combustion heat accompanying this combustion assists in heating the fiber reinforced plastic P. Therefore, combustible decomposition gas is not wasted, and the thermal efficiency of the heat treatment can be improved. The injection speed is not limited to the above range, and can be changed appropriately depending on the structure of the recycling device A, etc.

In order to efficiently remove the carbonized material generated during the heat treatment of the fiber-reinforced plastic P while preventing deterioration of the quality of the recovered fibers due to heat, it is preferable to set the temperature inside the treatment furnace 1 within the range of 500°C to 600°C. The temperature can be controlled by adjusting the thermal energy (heat adjustment) from the heat source 2 (burner 2) and the amount of oxygen (air) supplied from the oxygen supply port 6. In addition, the temperature rise can be suppressed by supplying superheated steam from the oxygen supply port 6.

The fibers removed from the furnace after heat treatment can be reused, for example, in the form of continuous fibers, or crushed in a crusher such as a ball mill or rod mill and used as aggregate, etc.

A modified version of the recycling device A shown in Figure 1 is shown in Figure 4. In the modified recycling device A, the position of the oxygen supply port 6 and the orientation of the oxygen supply pipe 7 connected to the oxygen supply port 6 are different. Compared to the recycling device A shown in Figure 1, etc., the recycling device A of this modified version is slightly less effective at drawing the decomposition gas to the heating port 3 (burner 2) side, but the auxiliary heating effect of burning the decomposition gas is exerted without any problems.

In the above-mentioned recycling device A, the heating port 3 and the exhaust port 4 are provided at a position lower than half of the total height inside the processing furnace 1, but preferably within a range of 1/3 of the total height from the bottom of the processing furnace 1, and more preferably within a range of 1/4 of the total height from the bottom of the processing furnace 1.

In the above-mentioned recycling device A, a burner 2 is used as the heat source 2 attached to the heating port 3, but other heat sources 2 such as electric heaters may be used as long as they can raise the internal temperature of the treatment furnace 1 to a level where the fiber reinforced plastic P can be heat treated.

In the above-mentioned recycling device A, carbonized materials are sufficiently removed in the treatment furnace 1, so even if the gas is cooled on its way from the exhaust pipe 5 to the secondary combustion furnace 8, adhesion of tar to the inner surface of the exhaust pipe 5 can be sufficiently reduced.

In the above-mentioned recycling device A, the burner 2 provided at the heating port 3 is provided with an oxygen supply port 6 (oxygen supply pipe 7), but it may be possible to configure the device without providing the oxygen supply port 6 (oxygen supply pipe 7).

The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. Therefore, the scope of the present invention is indicated by the claims, not by the above description, and is intended to include the equivalent meanings and all modifications of the claims.

1 Processing furnace 2 Heat source (burner)
3 Heating port 4 Exhaust port 5 Exhaust pipe 6 Oxygen supply port 7 Oxygen supply pipe 8 Secondary combustion furnace 9 Discharge pipe A Recycling device P Fiber reinforced plastic

Claims (6)

A fiber-reinforced plastic recycling device that heats a fiber-reinforced plastic (P) to recover fibers contained in the fiber-reinforced plastic (P),
a treatment furnace (1) for accommodating and heating the fiber-reinforced plastic (P);
a heating port (3) provided at a position lower than half the height of the entire height inside the processing furnace (1) and supplying thermal energy for heating the inside of the processing furnace (1);
an exhaust port (4) provided at a position lower than half the total height inside the processing furnace (1) and configured to exhaust gas inside the processing furnace (1) generated as a result of the heating;
A fiber reinforced plastics recycling device comprising: The fiber-reinforced plastic recycling device according to claim 1, wherein the treatment furnace (1) is provided with an oxygen supply port (6) for supplying oxygen to the heating port (3). The fiber-reinforced plastic recycling device according to claim 2, wherein the angle of the oxygen supplied from the oxygen supply port (6) is set so as to face from the exhaust port (4) side toward the heating port (3) side. A method for recycling fiber-reinforced plastics, comprising heating a fiber-reinforced plastic (P) to recover fibers contained in the fiber-reinforced plastic (P),
A method for recycling fiber-reinforced plastics, comprising: placing the fiber-reinforced plastics (P) inside a treatment furnace (1); supplying thermal energy to heat the inside of the treatment furnace (1) from a position lower than half the height of the interior of the treatment furnace (1); and exhausting gas inside the treatment furnace (1) generated as a result of heating the fiber-reinforced plastics (P) from a position lower than half the height of the interior of the treatment furnace (1). The method for recycling fiber-reinforced plastics according to claim 4, in which oxygen is supplied into the treatment furnace (1) together with the supply of thermal energy, decomposition gas of the fiber-reinforced plastic (P) generated as the fiber-reinforced plastic (P) is burned, and the heat of combustion assisted the heating of the fiber-reinforced plastic (P). The method for recycling fiber-reinforced plastics according to claim 5, wherein the temperature inside the treatment furnace (1) is controlled to be within the range of 500°C or more and 600°C or less by adjusting the amount of oxygen supplied.

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