JP7615647B2 - Method and equipment for treating waste carbon fiber reinforced resin - Google Patents

Description

The present invention relates to a method and apparatus for treating carbon fiber reinforced plastic waste.

Carbon fiber reinforced resin is widely used in aircraft and automobile parts because it is lightweight yet has high mechanical strength. However, it is difficult to process the large amounts of carbon fiber reinforced resin contained in used aircraft and automobiles. Furthermore, it is also problematic that a large amount of carbon fiber reinforced resin waste (unused scraps) is generated during the manufacturing process of aircraft and automobiles.

For example, the following Patent Document 1 describes a method of thermally decomposing CFRP (a type of carbon fiber reinforced resin) waste by heating the waste with superheated steam at 550°C to pyrolyze the resin contained in the waste. It also describes the use of the carbon fibers (contained in the CFRP) remaining after this heating process as recycled carbon fibers.

However, the technology described in Patent Document 1 below requires a lot of cost to obtain a heat source (e.g., fossil fuel) for heat-treating the carbon fiber reinforced resin waste. In addition, it is not possible to effectively utilize the flammable gases that are generated by heat-treating this waste.

JP 2017-82036 A

Therefore, the present invention aims to heat-treat waste carbon fiber reinforced resin at low cost and to effectively utilize the flammable gases generated by this heat treatment.

The method for treating carbon fiber reinforced resin waste according to the first aspect of the present invention includes a heat treatment process for heat treating carbon fiber reinforced resin waste, and a gas utilization process for utilizing the combustible gas generated from the waste in the heat treatment process as a heat source in a cement firing apparatus. In the heat treatment process, the waste is heat treated using exhaust gas from the cement firing apparatus and/or another gas generated using the exhaust gas as a heat source.

According to this first item, the heat (calories) contained in the exhaust gas from the cement calciner is used to heat-treat the carbon fiber reinforced resin waste, so that the waste can be heat-treated at low cost in the heat treatment process. In addition, the combustible gas generated in the heat treatment process can be effectively used as a heat source for the cement calciner.

The method for treating waste carbon fiber reinforced resin according to the second aspect of the present invention further includes a superheated steam generation process. In the superheated steam generation process, the exhaust gas is used as a heat source to generate the other gas, that is, superheated steam.

According to this second item, superheated steam can be generated at low cost by utilizing the heat (calories) contained in the exhaust gas from the cement calciner. In addition, this superheated steam can efficiently pyrolyze the resin contained in the carbon fiber reinforced resin waste, so the carbon fibers contained in this waste can be efficiently recovered as recycled carbon fibers.

In the gas utilization step of the method for treating waste carbon fiber reinforced resin according to the third aspect of the present invention, the combustible gas is utilized as a heat source in the cement burning apparatus by injecting the combustible gas into the cement kiln in the cement burning apparatus.

According to this third item, the combustible gas generated by the heat treatment of carbon fiber reinforced resin waste is blown into the inside of a cement kiln (a high-temperature environment of about 1450°C). Therefore, even if this combustible gas contains dioxins, the dioxins contained in this combustible gas can be decomposed while this combustible gas is used to burn the cement raw materials inside the cement kiln.

The carbon fiber reinforced resin waste treatment device according to the fourth aspect of the present invention includes a heat treatment device that heat treats the carbon fiber reinforced resin waste, and a cement calcination device that uses, as a heat source, a combustible gas generated from the waste in the heat treatment device to calcinate a cement raw material. The heat treatment device heat treats the waste using exhaust gas from the cement calcination device and/or another gas generated using the exhaust gas as a heat source.

According to this fourth item, the heat (calories) contained in the exhaust gas from the cement calciner is used to heat-treat the carbon fiber reinforced resin waste, so that the waste can be heat-treated in the heat treatment device at low cost. In addition, the combustible gas generated in the heat treatment device can be effectively used as a heat source for the cement calciner.

As described above, according to the present invention, it is possible to heat-treat waste carbon fiber reinforced resin at low cost and to effectively utilize the flammable gases generated by this heat treatment.

1 is a schematic diagram showing a carbon fiber reinforced resin waste treatment device according to an embodiment of the present invention.

Figure 1 is a schematic diagram showing a carbon fiber reinforced resin waste treatment device according to one embodiment of the present invention. As shown in Figure 1, this treatment device 1 includes a heat treatment device 2, a gas reforming device 3, a dust collection device 4, a carbon fiber recovery device 5, a cement calcination device 6, and a boiler 7. This treatment device 1 is installed on the premises of a cement manufacturing plant.

This processing device 1 processes waste material W made of carbon fiber reinforced resin. Here, examples of carbon fiber reinforced resin include composite materials of thermosetting resin and carbon fiber (CFRP) and composite materials of thermoplastic resin and carbon fiber (CFRTP). Examples of thermosetting resins include epoxy resin, unsaturated polyester resin, and phenol resin. Examples of thermoplastic resins include nylon resin and polyester resin. Examples of carbon fibers include those that have been used in the form of short fibers or continuous fibers or in the form of fabric (woven fabric, mat, etc.). Preferably, the waste material W is crushed in advance so that its maximum length is 5 cm or more and 30 cm or less.

The heat treatment device 2 performs a heat treatment process in which the waste material W made of carbon fiber reinforced resin is heat-treated in a non-oxidizing atmosphere at 300°C to 800°C. Specifically, the heat treatment device 2 heats the waste material W using air A taken in from the outside and superheated steam S supplied from the boiler 7. The non-oxidizing atmosphere means a space in which the oxygen concentration is 10% or less (preferably 5% or less). For example, a fixed furnace, a rotary kiln, a stoker furnace, a vertical furnace, or a fluidized bed furnace can be used as the heat treatment device 2.

As a result, most of the resin contained in the waste W is thermally decomposed, and the fixed carbon attached to the carbon fibers contained in the waste W is burned. Then, combustible gas C1 is generated from the waste W due to the thermal decomposition of the resin and the combustion of the fixed carbon, and the carbon fibers F contained in the waste W remain inside the heat treatment device 2. Note that heating the waste W at a temperature below 300°C is not preferable because it slows down the rate of thermal decomposition of the resin contained in the waste W. In addition, heating the waste W to a temperature higher than 800°C is not preferable because the carbon fibers contained in the waste W are oxidized, degrading the quality of the recycled carbon fibers.

The gas reforming device 3 performs a gas reforming process to reform the combustible gas C1 discharged from the heat treatment device 2. Specifically, the combustible gas C1 is heated with an amount of oxygen less than the theoretical oxygen requirement in an environment of 1000°C or higher and 1200°C or lower (preferably 1100°C or lower). This partially burns the carbon content (organic content) contained in the combustible gas C1 to generate combustible gas C2. The combustible gas C2 contains light components (carbon monoxide gas, methane gas, hydrogen gas, etc.) generated by decomposition of heavy hydrocarbons such as tar contained in the combustible gas C1.

Here, if the combustible gas C1 is heated to a temperature below 1000°C in the gas reforming device 3, the heavy hydrocarbons contained in the combustible gas C1 cannot be sufficiently decomposed. Also, if the combustible gas C1 is heated to a temperature above 1200°C in the gas reforming device 3, excessive heat will be added to the combustible gas C1 compared to the amount of heat required to decompose the heavy hydrocarbons contained in the combustible gas C1, which is undesirable because it will require more costs than necessary.

The dust collector 4 performs a dust collection process to collect the combustible gas C2 discharged from the gas reformer 3. The dust collector 4 collects carbon particles and the like contained in the combustible gas C2 discharged from the gas reformer 3 as dust D. For example, a bag filter or a cyclone can be used as the dust collector 4.

The carbon fiber recovery device 5 performs a carbon fiber recovery process to recover the carbon fiber F discharged from inside the heat treatment device 2.

The cement calcination device 6 performs a gas utilization process in which the combustible gas C3 discharged from the dust collection device 4 is used as a heat source for calcining the cement raw material (not shown). Specifically, the combustible gas C3 is blown into the cement kiln (not shown) from a burner (not shown) of the cement kiln, thereby utilizing the combustible gas C3 as a heat source in the cement kiln (cement calcination device 6).

The boiler 7 performs a superheated steam generation process in which the exhaust gas G from the cement burning device 6 is used as a heat source to generate superheated steam S.

Next, the operation of the processing device 1 shown in Figure 1 (corresponding to a method for processing carbon fiber reinforced resin waste according to one embodiment of the present invention) will be described. The operation of this processing device 1 is performed simultaneously and continuously in each of the components 2 to 7, but for the sake of convenience, the operation of each of the components 2 to 7 will be described in order here.

First, cement raw materials (not shown) are burned in the cement burning device 6. Next, exhaust gas G from the cement burning device 6 is introduced into a boiler 7 to generate superheated steam S. After that, the superheated steam S, air A, and waste material W of carbon fiber reinforced resin are supplied to the heat treatment device 2 to heat-treat the waste material W.

As a result, in a non-oxidizing atmosphere of 300°C to 800°C, which is the internal environment of the heat treatment device 2, the resin contained in the waste material W is thermally decomposed, and the fixed carbon attached to the carbon fibers contained in the waste material W is burned. Then, inside the heat treatment device 2, combustible gas C1 is generated from the waste material W due to the thermal decomposition of the resin and the combustion of the fixed carbon, and the carbon fibers F contained in the waste material W slide down the inclined bottom surface of the heat treatment device 2 and are discharged to the outside of the heat treatment device 2.

Here, the combustible gas C1 is drawn from inside the heat treatment device 2 to the gas reforming device 3 by an induction fan (not shown). Meanwhile, the carbon fiber F discharged from inside the heat treatment device 2 is collected in the carbon fiber recovery device 5. The collected carbon fiber F can be used as recycled carbon fiber or as fuel for the cement burning device 6.

In the gas reformer 3, the combustible gas C1 is reformed to generate the combustible gas C2. The combustible gas C2 is separated into combustible gas C3 and dust D by collecting dust in the dust collector 4. Furthermore, the combustible gas C3 is blown into the cement kiln of the cement firing device 6, and used as a heat source (combustion gas) in the cement kiln (cement firing device 6). Furthermore, the collected dust D is used as solid fuel in the cement firing device 6.

As described above, according to the above embodiment, the waste material W made of carbon fiber reinforced resin is heat-treated using the heat (calories) contained in the exhaust gas G from the cement burning device 6, so that the waste material W can be heat-treated at low cost in the heat treatment device 2. In addition, the combustible gases C1 to C3 generated in the heat treatment device 2 can be effectively used as a heat source in the cement burning device 6.

In addition, according to the above embodiment, the heat (calories) contained in the exhaust gas G from the cement burning device 6 can be used to generate superheated steam S at low cost. In addition, by heat treating the carbon fiber reinforced resin waste W with this superheated steam S, the resin contained in the waste W can be efficiently pyrolyzed, and the carbon fibers F contained in the waste W can be efficiently recovered as recycled carbon fibers.

Furthermore, according to the above embodiment, the combustible gases C1 to C3 generated by the heat treatment of the carbon fiber reinforced resin waste W are blown into the inside of the cement kiln (a high-temperature environment of about 1450°C). Therefore, even if the combustible gases C1 to C3 contain dioxins, the combustible gases C1 to C3 can be used to burn the cement raw materials inside the cement kiln, while the dioxins contained in the combustible gases C1 to C3 can be decomposed inside the cement kiln.

In addition, in the above embodiment, the combustible gas C3 is used as the heat source in the cement burning device 6, but the combustible gases C1 and C2 can also be used as the heat source in the cement burning device 6.

In addition, in the above embodiment, the waste W inside the heat treatment device 2 is heat-treated by superheated steam S, but the waste W inside the heat treatment device 2 may be heat-treated by exhaust gas G from the cement burning device 6. In addition, nitrogen gas, argon gas, etc. may be heated by exhaust gas G from the cement burning device 6, and the waste W inside the heat treatment device 2 may be heat-treated by the heated nitrogen gas, argon gas, etc.

In the above embodiment, the combustible gas C3 is injected into the cement kiln of the cement burning device 6, but it can also be injected into a calciner (not shown) or a preheater (not shown) in the cement burning device 6. In addition, the recycled carbon fibers recovered by the carbon fiber recovery device 5 can be classified according to the intended use by screening, gravity sorting, optical sorting, etc.

In this way, according to the above embodiment, the waste material W can be heat-treated by the heat treatment device 2 using superheated steam S without using fossil fuels, and the cement raw materials can be burned by the combustible gas C3 without using fossil fuels in the cement burning device 6, so that the amount of carbon dioxide emitted into the atmosphere from these devices 2 and 6 can be kept low. Furthermore, even if the combustible gases C1 to C3 discharged from the heat treatment device 2 contain dioxins, these combustible gases C1 to C3 can be used to burn the cement raw materials inside the cement kiln (cement burning device 6), and the dioxins contained in these combustible gases C1 to C3 can be decomposed inside the cement kiln without being released into the atmosphere.

According to the above embodiment, the carbon fiber reinforced plastic waste W can be recovered in the carbon fiber recovery device 5 and used as recycled carbon fiber (expensive and versatile material), and the combustible gas C1 discharged from the heat treatment device 2 can be used as a heat source in the cement burning device 6. In particular, as described above, the carbon fiber reinforced resin waste W can be treated with various resins such as epoxy resin, unsaturated polyester resin, phenol resin, nylon resin, and polyester resin, so that various types of carbon fiber reinforced resin waste W can be recycled. Furthermore, even if the carbon fiber reinforced resin waste W contains other resin materials different from the carbon fiber reinforced resin, it can be treated in the same way as the resin contained in the carbon fiber reinforced resin. This makes it possible to realize zero emissions in the treatment of the carbon fiber reinforced resin waste W.

1 Carbon fiber reinforced resin waste treatment device 2 Heat treatment device 3 Gas reforming device
4 Dust collector 5 Carbon fiber recovery device 6 Cement burning device 7 Boiler A Air C1-C3 Combustible gas D Dust F Carbon fiber G Exhaust gas S Superheated steam W Carbon fiber reinforced resin waste

Claims (4)

a heat treatment process in which carbon fiber reinforced resin waste is heat treated in a non-oxidizing atmosphere having an oxygen concentration of 10% or less and a temperature of 800° C. or less , thereby thermally decomposing the resin contained in the waste to generate a combustible gas, and further combusting fixed carbon attached to the carbon fibers contained in the waste ;
a gas utilization step of utilizing the combustible gas generated from the waste in the heat treatment step as a heat source in a cement burning apparatus ;
A carbon fiber recovery process for recovering the carbon fibers obtained by the heat treatment in the heat treatment process ,
A method for treating carbon fiber reinforced resin waste, characterized in that in the heat treatment step, the waste is heat-treated using exhaust gas from the cement burning apparatus and/or another gas generated by utilizing the exhaust gas as a heat source. Further comprising a superheated steam generating step,
2. The method for treating waste carbon fiber reinforced resin according to claim 1, wherein in the superheated steam generating step, the exhaust gas is utilized as a heat source to generate the separate gas, that is, the superheated steam. The method for treating waste carbon fiber reinforced resin according to claim 1 or 2, characterized in that in the gas utilization step, the combustible gas is utilized as a heat source in the cement burning device by injecting the combustible gas into the inside of a cement kiln in the cement burning device. a heat treatment device for heat-treating carbon fiber reinforced resin waste in a non-oxidizing atmosphere having an oxygen concentration of 10% or less and 800° C. or less , thereby thermally decomposing the resin contained in the waste to generate a combustible gas, and further combusting fixed carbon attached to the carbon fibers contained in the waste ;
a cement calcination device that uses the combustible gas generated from the waste in the heat treatment device as a heat source to calcinate a cement raw material ;
a carbon fiber recovery device that recovers the carbon fibers obtained by the heat treatment in the heat treatment step ,
The heat treatment device heats the waste using exhaust gas from the cement burning device and/or another gas generated by utilizing the exhaust gas as a heat source.

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