JP2017066383A - Method for processing carbon fiber-reinforced plastic and method for manufacturing fuel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for processing a carbon fiber-reinforced plastic capable of improving crushability while maintaining recovery rate high when used as a fuel and a method for manufacturing the fuel capable of effectively using the carbon fiber-reinforced plastic, which is a waste, as the fuel.SOLUTION: There are provided a method for processing a carbon fiber-reinforced plastic by conducting a heating treatment on the carbon fiber-reinforced plastic according to conditions 1 and 2 and a method for manufacturing a fuel including a process for processing the carbon fiber-reinforced plastic by the method for processing the carbon fiber-reinforced plastic and a process for pulverizing the carbon fiber-reinforced plastic after the treatment. (Condition 1) The heating temperature is set in a range of 300 to 500°C. (Condition 2) The heating time is set in a range of 10 minutes to 12 hours depending on the set heating temperature.SELECTED DRAWING: None

Description

  The present invention relates to a treatment method for reducing the mechanical strength of a carbon fiber reinforced plastic, and a fuel production method using a carbon fiber reinforced plastic obtained by treating the carbon fiber reinforced plastic with the treatment method.

  Carbon fiber reinforced plastic (hereinafter also referred to as “CFRP”) is lightweight and excellent in mechanical strength such as high strength and high elasticity, so it is small in size such as tennis rackets, golf club shafts, fishing rods, etc. To large-sized products for industrial use such as automobiles and aircraft, and is used in large quantities. Not only those products but also defective products generated in the manufacturing process are added, and it is considered that the amount of CFRP discarded in the future will continue to increase, and it is required to effectively use these as resources.

  As a recycling technique, various techniques for separating and recovering carbon fibers from CFRP waste have been studied. For example, in Patent Document 1, as a treatment method of CFRP, carbon fiber reinforced plastic is not burned in a gas atmosphere in which the oxygen concentration is in the range of 3 to 18% by volume and the temperature is in the range of 300 to 600 ° C. It has been proposed to treat, pyrolyze the plastic and recover the carbon fiber. However, even if carbon fibers are recovered from waste, the fibers are often shortened or the strength is reduced. Therefore, material recycling and chemical recycling are difficult, and there are many final landfills. However, landfill disposal will become difficult in the future due to securing landfill sites and strengthening regulations.

  After all, thermal recycling using CFRP as a fuel is an effective method because it can achieve both recycling and final disposal. One method is to use fuel in cement manufacturing processes. This means that it is possible to cope with an increase in the processing amount, that it can be processed even when waste other than CFRP is mixed, that it can handle CFRP of various shapes and compositions, and that no waste is generated by the processing. This is an effective recycling method.

  Patent Document 2 discloses a carbon in which waste plastic containing carbon fiber is supplied to a cement kiln and exhaust gas generated by performing a combustion process is supplied to a dust collector to collect dust in the exhaust gas. In the incineration processing method for waste plastics containing fibers, the waste plastics containing carbon fibers are pulverized so as to have an average particle diameter of 3 mm or less, and supplied to a position where the internal temperature of the cement kiln is 1200 ° C. or more. It is described that it can be used as a part of fuel in a cement manufacturing apparatus without performing fiber separation.

JP-A-6-99160 JP 2007-131463 A

However, in the processing method described in Patent Document 2, since CFRP is excellent in mechanical strength, the grinder is severely worn and a large amount of grinding energy is required. Therefore, the method of grinding CFRP to 3 mm or less is Not realistic. That is, CFRP is difficult to crush and finely pulverize because carbon fiber and resin have a high unity and high strength, and until now it has been difficult to use as a fuel. Moreover, in the processing method described in Patent Document 1, the recovery rate when used as fuel was low. Here, the recovery rate refers to the ratio of the calorific value of CFRP after heating to the calorific value of CFRP before heating. More specifically, instead of comparing the unit calorific value (J / g) obtained by measurement, the material balance of the calorific value taking into account the weight before treatment and the weight after treatment is shown. That is, the recovery rate is obtained by the following formula.
Recovery rate = unit calorific value after treatment x recovered weight / unit calorific value before treatment x treated weight Note that in this specification, the calorific values of carbon and resin are considered to be substantially equal, and the residual weight is approximately equal to the recovery rate.

  An object of the present invention is to provide a carbon fiber reinforced plastic processing method capable of improving the pulverization property while maintaining a high recovery rate when used as a fuel, and a fuel capable of effectively using a carbon fiber reinforced plastic as a waste material as a fuel. It is in providing the manufacturing method of.

  The present inventors have found that even when CFRP having high strength is heated at an appropriate temperature and for an appropriate time, the mechanical strength is lowered and can be finely pulverized, and the present invention has been completed. More details are as follows. That is, when CFRP is heated, the resin volatilizes and decomposes, so that the weight is reduced and the heat loss is lost, and the recovery rate is reduced. On the other hand, since carbon fiber has higher thermal stability than resin, weight loss and heat loss hardly occur. The higher the recovery rate, the smaller the calorific value loss due to heating and the greater the fossil fuel replacement amount. Moreover, generation | occurrence | production of noxious gas, such as generation | occurrence | production of tar and carbon monoxide, can also be suppressed. Based on these points, the present inventors have studied to find the best point to improve the grindability while optimizing the heating conditions, minimizing the volatilization and decomposition of the resin and maintaining a high recovery rate. Completed the invention.

The method for treating a carbon fiber reinforced plastic according to the present invention is characterized in that the carbon fiber reinforced plastic is subjected to a heat treatment according to the following conditions 1 and 2.
(Condition 1) The heating temperature is set within a range of 300 to 500 ° C.
(Condition 2) The heating time is set within a range of 10 minutes to 12 hours according to the set heating temperature.

  In the method for treating a carbon fiber reinforced plastic according to the present invention, the heating temperature and the heating time are set according to the above conditions 1 and 2, so that the carbon and hydrogen bonds in the molecular structure of the carbon fiber reinforced plastic are oxidized, and the polymer structure As a result, the mechanical strength is lowered due to the change in physical properties and the physical properties are changed. As a result, fine pulverization (for example, 0.1 mm or less) becomes easy. Further, it can be finely pulverized to the same level as or more than that of generally used coal, and can be suitably used as a fuel.

  In the present invention, the heating temperature is set in the range of 300 to 500 ° C. according to the condition 1, but if it is less than 300 ° C., the treatment takes a long time, and if it exceeds 500 ° C., the recovery rate decreases, and tar and harmful Since the amount of gas generated increases, the resin softened by tar adheres to the inside of the processing apparatus. That is, in the present invention, since heating is performed at a relatively low temperature of 500 ° C. as the upper limit, it is possible to prevent adhesion of resin in the processing apparatus.

  In the present invention, the heating time is set within a range of 10 minutes to 12 hours according to the set heating temperature according to the condition 2. However, the higher the heating temperature, the shorter the heating time, and vice versa. Set the heating time longer. Further, the heating time is set shorter as the CFRP to be processed is smaller, and the heating time is set longer as the CFRP is larger.

  In the carbon fiber reinforced plastic treatment method of the present invention, it is preferable to perform heat treatment so that the weight reduction rate of the carbon fiber reinforced plastic is 5 to 50%. Heating causes a part of the resin in the carbon fiber reinforced plastic to volatilize, resulting in a weight reduction. By minimizing the weight reduction, it is possible to achieve both fuel recovery and fine pulverization. It can be achieved more efficiently.

  Furthermore, in the processing method of the carbon fiber reinforced plastic of this invention, the content rate of the volatile matter in the said carbon fiber reinforced plastic obtained by JISM8812 (2004) (industrial analysis) is used for the weight reduction rate of the said carbon fiber reinforced plastic. It is preferable to heat-process so that the value remove | divided by may become 15 to 70%. By performing the heat treatment under such conditions, the CFRP can be easily pulverized and the resin can also be recovered as fuel.

  The fuel production method of the present invention includes a step of treating the carbon fiber reinforced plastic by the carbon fiber reinforced plastic treatment method of the present invention and a step of pulverizing the carbon fiber reinforced plastic after the treatment. Features. The carbon fiber reinforced plastic after the treatment is preferably pulverized to 3 mm or less.

  The fuel production method of the present invention uses carbon fiber reinforced plastic that has been processed by the above-described carbon fiber reinforced plastic processing method of the present invention and has reduced mechanical strength. Therefore, fine pulverization is easy. A fuel having a particle diameter of 0.1 mm or less, which is equal to or less than 5 mm, or similar to pulverized coal, can be easily produced. That is, the carbon fiber reinforced plastic as a waste material can be effectively used as a fuel.

The whole block diagram of the system for implementing the processing method of the carbon fiber reinforced plastics of this invention. The graph which shows the combustion rate with respect to the heating time of each sample used in the Example.

  Embodiments of the present invention will be described below.

In the CFRP processing method of the present embodiment, the CFRP is heat-treated according to the following conditions 1 and 2.
(Condition 1) The heating temperature is set within a range of 300 to 500 ° C.
(Condition 2) The heating time is set within a range of 10 minutes to 12 hours according to the set heating temperature.

  By performing heat treatment according to conditions 1 and 2, the mechanical strength of CFRP can be reduced. For example, if the heating temperature is set to 300 ° C., the heating time is set to 2 hours and similarly to 400 ° C. Thus, it is preferable to set the relationship between the heating temperature and the heating time so as to be in inverse proportion, such as 1 hour if set to 500 ° C. and 10 minutes if set. In addition, the preferred relationship between the heating temperature and the heating time varies depending on the size of the CFRP and other conditions, so it is preferable to set appropriately.

  As a heating means for performing the heat treatment, any heating means can be used as long as it can be set in a temperature range of 300 to 500 ° C., and examples thereof include a fixed furnace, a stoker furnace, a rotary kiln furnace, a fluidized bed furnace, a vertical furnace, and a multistage furnace.

  The heat treatment may be any of air, an oxidizing atmosphere, a reducing atmosphere, and an inert atmosphere. However, an oxidizing atmosphere is preferable because the mechanical strength of CFRP can be reduced in a shorter time.

  In the heat treatment, the heat treatment is preferably performed so that the weight reduction rate of CFRP is 5 to 50%, more preferably 10 to 40%, and still more preferably 15 to 35%. The reason why the weight of CFRP decreases is that the resin volatilizes, and the weight reduction rate varies depending on the type of resin, but the above numerical range is for epoxy resin.

  Further, in the heat treatment, it is preferable to perform the heat treatment so that the weight reduction rate of CFRP with respect to the volatile content in CFRP obtained by JIS M8812 (2004) (industrial analysis) is 15 to 70%. It is more preferably 20 to 65%, and further preferably 30 to 55%. By making this value 15% or more, CFRP can be finely pulverized. Moreover, resin is also collect | recovered as a fuel by making the said value 70% or less.

  As described above, the mechanical strength of CFRP is reduced by the CFRP processing method of the present embodiment, so that the pulverization property is improved, and in particular, the fine pulverization becomes easy. However, when the CFRP to be processed exceeds 10 cm, the heating time becomes longer and a load is applied, the amount of processing is reduced, or the adjustment of the heating time becomes difficult. Therefore, the heat treatment may be performed after roughly pulverizing the CFRP to be processed to about several mm.

  On the other hand, the fuel production method of the present embodiment includes a step of treating the carbon fiber reinforced plastic and a step of pulverizing the treated carbon fiber reinforced plastic by the carbon fiber reinforced plastic treatment method. Since the process of processing CFRP has already been described, the process of pulverizing CFRP will be described below.

  In the step of pulverizing the CFRP, the mechanical strength of the CFRP is reduced by the heat treatment in the previous step, so that fine pulverization is easy. Therefore, an apparatus having a strong pulverizing ability is not necessarily required as the pulverizing apparatus. Examples of the pulverizer include a hammer mill, a cutter mill, a shear crusher, a roll crusher, an impact crusher, a rotary mill, a ball mill, a disk mill, and a vertical mill. In addition, when coal and other materials used as fuel in the existing equipment and CFRP are mixed and pulverized at the same time, no new pulverization equipment is required, and pulverization is easy, and the properties of the fuel change greatly. This is preferable.

  As for the particle diameter of CFRP after pulverization, the 3 mm sieve residue is preferably 10% or less, and the 0.5 mm sieve residue is more preferably 10% or less. If the particle size of CFRP exceeds 3 mm, the exhaust gas system is adversely affected. Specifically, the unburned carbon fiber causes a charging failure in the electric dust collector for collecting the dust, and the collecting performance is lowered. The larger the CFRP particle size, the more entangled and cotton-like fibers are generated, which causes abnormal re-scattering in the electrostatic precipitator system, and adheres to and stays on the device wall surface, piping, discharge electrode, and dust collection electrode. It is.

  By making the particle diameter of CFRP after pulverization 0.5 mm or less, it becomes difficult to reduce the distance between the electrodes, which causes abnormal re-scattering, and the cotton fiber entangled with CFRP does not occur. Trouble is reduced. Even when the dust is collected by the bag filter, by setting the particle diameter to 0.5 mm or less, it is possible to prevent the cotton-like fibers entangled with CFRP from adhering to and staying on the apparatus wall surface and the pipe to the apparatus. Further, it is prevented that the cotton-like fibers are scattered again when the deposits are wiped off from the filter cloth and stayed without being collected as dust collection dust. Furthermore, by setting the particle diameter to 0.1 mm or less, even if it adheres to the discharge electrode of the electrostatic precipitator without burning, inter-electrode discharge is less likely to occur, and the decrease in applied voltage is about the variation of the routine operation.

  Also, if the CFRP particle size is 0.1 mm or less, the burn-out time will be about the same as that of pulverized coal, so it can be completely burned even at relatively low temperatures such as kiln bottoms in cement plants, and carbon fibers Effectively used as fuel.

  In the present invention, “the particle size of the Amm sieve residue is 10% or less” means that the weight of the particles remaining on the sieve having an aperture of Amm is 10%.

  Next, a method for producing fuel will be described with reference to the drawings. FIG. 1 shows an example of a system for carrying out the fuel production method of the present invention. This processing system 1 includes a tank 2 for storing received CFRP after the heat treatment, and a CFRP from the tank 2 in stages. Are composed of a biaxial shear crusher 4, a cutter mill 5 and a vertical mill 6, and a charging device 7 for charging the pulverized product P from the vertical mill 6 into the cement manufacturing apparatus 10.

  The biaxial shear crusher 4 is a device in which a sharp rotary blade is provided on each of two shafts, and the object to be processed is bitten and crushed. Instead of the biaxial shear crusher 4, a uniaxial shear crusher, a four-axis shear crusher, a roll crusher, an impact crusher, or the like may be used.

  The cutter mill 5 is a device for crushing a processing object so as to be sandwiched by using a shearing force with a cutter attached to a rotor and a fixed blade attached to a casing, and can receive an impact force. It is suitable for crushing things that are difficult to crush finely by absorbing force or extending. Instead of the cutter mill 5, a rotary mill, a hammer mill or the like may be used.

  The vertical mill 6 is a device that has a horizontally rotating table and a plurality of rollers mounted along the upper surface of the table recess, and pulverizes the object to be processed between the table and the rollers. The object to be processed moves in the direction of the outer periphery of the table, and is carried to the separator by an ascending air current and classified. Instead of the vertical mill 6, a ball mill, a disk mill or the like may be used.

  As the charging device 7, a screw type, an ejector type air flow type, a rotary feeder, a screw feeder or the like is used.

  The cement manufacturing apparatus 10 using the pulverized product P obtained by the processing system 1 as a fuel includes a preheater 16 in which cyclones are stacked in multiple stages to preheat the cement raw material CR, and a calcining furnace 15 for calcining the cement raw material CR. The cement kiln (rotary kiln) 11 that includes the main burner 12 and the like and fires the cement raw material CR, and the clinker cooler 13 that cools the cement clinker discharged from the cement kiln 11 and the like.

  Next, a fuel combustion processing method by the processing system 1 having the above configuration will be described.

  After the received CFRP is temporarily stored in the tank 2, the CFRP particle size is 0.2 mm in the final order in the biaxial shear crusher 4, the cutter mill 5, and the vertical mill 6. Crush to the following.

  The pulverized product P from the vertical mill 6 is used as fuel by being fed into the kiln 11a and the kiln bottom 11b of the cement kiln 11 through the feeding device 7 or by being fed into the cement kiln 11 from the main burner 12. Then, the cement raw material CR is fired (the illustrated example shows the case where it is put into the kiln bottom 11b). The cement kiln 11 may be charged from any one of the kiln front 11a, the kiln bottom 11b, and the main burner 12, or may be charged from a plurality of locations. Among these, in order to eliminate unburned carbon fiber, it is preferable to use the main burner 12.

  In the above embodiment, the pulverized material P from the vertical mill 6 is charged into the cement manufacturing apparatus 10 by the charging device 7. However, a tank is provided between the vertical mill 6 and the charging device 7, and the pulverized material P is Once stored in a tank, the cement production apparatus 10 may be charged by the charging apparatus 7.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[Example 1]
30 g of CFRP crushed to 1 to 30 mm is put into a box-type electric furnace (Yamato Scientific Co., Ltd .; FP-41), set to the heating temperature and heating time shown in Table 1, and subjected to heat treatment, and the weight before and after heating. The weight reduction rate was confirmed. The results are shown in Table 1.

  From Table 1, it can be seen that in order to reduce the weight of CFRP above a certain level, the heating time is shortened as the heating temperature is higher, and conversely, the heating time is set longer as the heating temperature is lower.

  Next, 10 g of CFRP which was set to the heating temperature and heating time shown in Table 1 and subjected to the heat treatment was collected and pulverized using a disk mill (manufactured by Harzock; HSM-100A) at a pulverization time of 60 seconds. Further, sieving was performed using sieves having an opening of 1 mm, 0.5 mm, and 0.1 mm. The particle size distribution after pulverization is shown in Table 2.

  From Table 2, when the heating temperature and the heating time were 300 ° C. for 30 minutes or more, 400 ° C. for 10 minutes or more, and 500 ° C. for 10 minutes or more, the particle size distribution of less than 0.1 mm increased. Therefore, the heat-treated and finely pulverized CFRP at such heating temperature and heating time contributes to the use as fuel.

[Example 2]
30 g of CFRP crushed to 2 to 5 mm was put into a box-type electric furnace (Yamato Scientific Co., Ltd .; FP-41), set to the heating temperature and heating time shown in Table 3, and subjected to heat treatment on the CFRP. The weight reduction rate was confirmed. The results are shown in Table 3. Table 4 shows the weight reduction rate of CFRP with respect to the content of volatile components in CFRP obtained by JIS M8812 (2004) (industrial analysis). In addition, the content rate of the volatile matter of untreated CFRP was 33.8%.

  From Table 4, in order to reduce the weight reduction rate of CFRP with respect to the volatile content of CFRP more than a certain value, the heating time is shortened as the heating temperature is higher, and conversely, the heating time is set longer as the heating temperature is lower. I know it ’s good.

  Subsequently, 10 g of CFRP which was set to the heating temperature and heating time shown in Table 3 and Table 4 and subjected to the heat treatment was collected and pulverized for 60 seconds using a disk mill (Harzock, HSM-100A). After pulverization, sieving was performed using a sieve having openings of 2 mm, 1 mm, 0.5 mm, and 0.1 mm. It shows in Table 5 about the particle size distribution after each grinding | pulverization.

  From Table 5, when the heating temperature / heating time is 300 ° C. · 2 hours or more, 350 ° C. · 30 minutes or more, 400 ° C. · 10 minutes or more, 450 ° C. · 10 minutes or more, 500 ° C. · 10 minutes or more, 0 It can be seen that the particle size distribution of less than 1 mm has increased.

  Next, the effect on the electrostatic precipitator when used as a fuel in a cement factory was evaluated. About the untreated product of Table 5 and the pulverized material treated at 400 ° C. for 1 hour, 400 g per hour was charged into a cement kiln kiln bottom (clinker production amount 150 t / h). In the case of an untreated product, the applied voltage of the electrostatic precipitator dropped from 50 kV to 35 kV after 30 minutes. On the other hand, the treated product never fell below 45 kV.

  Therefore, the CFRP embrittlement obtained by the processing method of the CFRP of the present invention can be easily pulverized to a particle size of 0.1 mm or less that hardly affects the electrostatic precipitator compared to the untreated CFRP. I understand.

  Next, in order to evaluate the combustibility (weight reduction rate when burned for a predetermined time) with respect to pulverized coal, which is the main fuel of the cement kiln, with respect to the untreated CFRP and the pulverized material treated at 400 ° C. for 1 hour, A combustion test was carried out using a furnace (diameter 42 mm, temperature 1450 ° C., atmospheric gas flow rate 1 L / min, test amount 1 g). Table 6 shows the particle size (median diameter D50) of the sample. The weight reduction rate (burning rate) during the burning test is shown in FIG.

  From FIG. 2, it can be seen that the combustion rate of CFRP is slower than that of pulverized coal, and the combustion rate of the CFRP embrittlement is slower. In addition, for both CFRP and CFRP embrittled material, the burning rate decreases as the particle size increases. However, it can be seen that both the CFRP and the CFRP embrittled material have a burning time (6 minutes) substantially equal to that of pulverized coal or untreated CFRP if the particle size is 0.1 mm or less.

  Therefore, it can be seen that the CFRP embrittlement obtained by the CFRP treatment method of the present invention can be easily pulverized to a particle size until the burn-out time is the same as that of pulverized coal, compared to the case where it is not treated. .

DESCRIPTION OF SYMBOLS 1 Processing system 2 Tank 4 Biaxial shear crusher 5 Cutter mill 6 Vertical mill 7 Input apparatus 10 Cement production apparatus 11 Cement kiln 12 Main burner 13 Clinker cooler 15 Pre-heating furnace 16 Preheater CR Cement raw material P Ground material CFRP Carbon fiber reinforcement plastic

Claims (6)

A method for treating a carbon fiber reinforced plastic, comprising subjecting the carbon fiber reinforced plastic to a heat treatment according to the following conditions 1 and 2.
(Condition 1) The heating temperature is set within a range of 300 to 500 ° C.
(Condition 2) The heating time is set within a range of 10 minutes to 12 hours according to the set heating temperature.   The method for treating carbon fiber reinforced plastic according to claim 1, wherein the carbon fiber reinforced plastic is subjected to heat treatment so that a weight reduction rate of the carbon fiber reinforced plastic is 5 to 50%.   In the processing method of the carbon fiber reinforced plastics of Claim 1 or 2, the weight reduction | decrease rate of the said carbon fiber reinforced plastics is volatile matter in the said carbon fiber reinforced plastics obtained by JISM8812 (2004) (industrial analysis). A method for treating a carbon fiber reinforced plastic, which is subjected to a heat treatment so that a value divided by a content rate is 15 to 70%. The process of processing a carbon fiber reinforced plastic by the processing method of the carbon fiber reinforced plastic according to any one of claims 1 to 3,
Crushing the carbon fiber reinforced plastic after the treatment;
A fuel production method comprising: The method for producing a fuel according to claim 4, wherein
A method for producing a fuel, wherein the treated carbon fiber reinforced plastic is pulverized to 3 mm or less. The method for producing a fuel according to claim 4, wherein
A method for producing fuel, wherein the treated carbon fiber reinforced plastic is pulverized to 0.1 mm or less.