JP2014193788A - Incineration apparatus of waste carbon fiber-reinforced plastic, and incineration method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus capable of incinerating carbon fiber-reinforced plastic without crushing the plastic into small pieces and without blocking a function of a dust collector, and furthermore effectively utilizing thermal energy generated during incineration.SOLUTION: An incineration apparatus comprises: a combustion furnace 2; a first hot gas piping 10 which branches hot gas G1 in the combustion furnace; and an external heating furnace 11, in which the external heating furnace is equipped with: an input port 11a to which waste carbon fiber-reinforced plastic is input; a hot gas introduction port 11b connected with the first hot gas piping; and conveying means 11b for conveying waste carbon fiber-reinforced plastic in the external heating furnace, waste carbon fiber-reinforced plastic mounted on the conveying means is incinerated by hot gas supplied via the first hot gas piping, ash of the incinerated waste carbon fiber-reinforced plastic is discharged from an ash discharge port 11c, and the apparatus also comprises a second hot gas piping 13 which returns hot gas G2 generated in the external heating furnace during the incineration to the combustion furnace.

Description

  The present invention relates to an incineration processing apparatus and an incineration processing method for the purpose of thermal recycling of defective products generated in the manufacturing process and used and discarded carbon fiber reinforced plastic (hereinafter also referred to as “CFRP”). Is.

  CFRP is lightweight and has excellent mechanical strength such as high strength and high elasticity, so it can be used for small items such as tennis rackets, golf club shafts, fishing rods, etc., and large items for industrial use such as automobiles and aircraft. Widely used in large quantities. Not only those products but also defective products generated in the manufacturing process are added, and the amount of CFRP to be discarded in the future will continue to increase, and it is required to use these effectively as resources.

  As a recycling technique, various techniques for separating and recovering carbon from CFRP waste have been studied. However, even when 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 is an effective recycling method because it is possible to cope with an increase in the amount of processing and waste is not generated by the processing.

In Patent Document 1, as a method for incinerating waste FRP, (a) waste FRP is crushed into a lump of 50 mm or less, and this lump is put into a preheater in a cement manufacturing process and used as an auxiliary fuel; (b ) Waste FRP is crushed to a particle size of 3 mm or less, and this crushed product is put into a calcining furnace in the cement manufacturing process and used as an auxiliary fuel. (C) Waste FRP is pulverized to a particle size of 90 μm or less, and cement Supplying to the pulverized coal burner of a manufacturing process, co-firing with pulverized coal, etc. are proposed.
However, as proposed in Patent Document 1, when CFRP is put into a preheater or a calcining furnace instead of FRP, carbon fibers are difficult to burn, and therefore, the unburned carbon fibers are scattered, and the scattered carbon fibers are It reaches the electric dust collector along with the exhaust gas and is collected. Here, the scattered unburned carbon fibers locally change the conductivity of the electrostatic precipitator, the electric precipitator will not function normally, and the dust collection efficiency of the electrostatic precipitator may be reduced, and dust may be generated. is there.

On the other hand, Patent Document 2 points out the following problems. There is an attempt to crush the waste fiber reinforced resin article to an appropriate particle size and use it as a solid fuel for cement firing (Japanese Patent Laid-Open No. 6-8247). There is a problem that the reinforcing fibers protrude from the crushing cross section and are easily broken, and the broken fine fibers are scattered in the middle of conveyance and the working environment is contaminated. In order to cope with this problem, Patent Document 2 proposes to use a crushed granule of a waste fiber reinforced resin article as a core and a coating layer made of a thermoplastic resin formed on the surface thereof. Yes.
However, even in the technique described in Patent Document 2, the problem that the dust collection efficiency is lowered still occurs because the carbon fiber remaining unburned in the incinerator is scattered and collected by the electric dust collector. To do.

In Patent Document 3, waste plastic containing carbon fiber is supplied to a cement kiln, exhaust gas generated by performing a combustion treatment is supplied to a dust collector, and soot dust in the exhaust gas is collected. Proposed to incinerate waste plastics containing carbon fiber so that the waste plastics containing carbon fiber are crushed so that the average particle size is 3mm or less and the internal temperature of the cement kiln is 1200 ° C or higher. doing.
However, since the carbon fiber reinforced plastic has excellent mechanical strength, the grinding machine is heavily worn and a large amount of pulverization energy is required. Therefore, a method of pulverizing the carbon fiber reinforced plastic to 3 mm or less is not realistic. .

Patent Document 4 proposes a valuable material recovery device comprising a roasting furnace attached to a cement baking apparatus and a return path for returning exhaust gas from the roasting furnace to the cement baking apparatus.
However, since the invention of Patent Document 4 aims to recover valuable materials, CFRP cannot be completely incinerated. In particular, in the case of CFRP having a large size, unburned residue tends to be generated, but the invention of Patent Document 4 cannot cope with it.

Japanese Patent Laid-Open No. 6-8247 JP 2001-49273 A JP 2007-131463 A JP2013-14802

The problems of the background art described above are summarized as follows.
Although CFRP is useful, it is often landfilled because it is difficult to reuse the fiber itself. However, it should be reused as resources from now on. At that time, thermal recycling that can be used as a fuel in the cement manufacturing process, etc. can be considered, but in the case of a system that burns CFRP in a combustion furnace, as described above, the unburned carbon fiber hinders the function of the dust collector. There are things to do. For this reason, it is necessary to break up CFRP into fine pieces and burn it, but it is difficult to make pieces into pieces because CFRP has high mechanical strength.

  The present invention has been made in view of the problems of the background art described above, and can be incinerated without finely pulverizing the waste carbon fiber reinforced plastic and without inhibiting the function of the dust collector, It is another object of the present invention to propose an incineration processing apparatus and an incineration processing method for waste carbon fiber reinforced plastic that can effectively use thermal energy generated during the incineration.

The above-described problems have been solved by the following incineration processing apparatus and incineration processing method.
[1] A combustion furnace, a first hot gas pipe for branching a hot gas (first hot gas) of the combustion furnace from the combustion furnace, and an external heat furnace, wherein the external heat furnace is a waste carbon An inlet for feeding fiber reinforced plastic; a hot gas inlet connected to the first hot gas pipe; and a transport means for transporting waste carbon fiber reinforced plastic in an external heating furnace; The waste carbon fiber reinforced plastic placed on the conveying means is incinerated by the hot gas supplied through the hot gas pipe 1, and the ash of the incinerated waste carbon fiber reinforced plastic is discharged from the ash outlet. And preferably, a second hot gas pipe for returning the hot gas (second hot gas) generated in the external heating furnace to the combustion furnace when the waste carbon fiber reinforced plastic is incinerated. More preferably, unburned waste coal The fiber-reinforced plastic, characterized in that it comprises the remaining conveying means burning transported to inlet of the outer heat furnace from the ash discharge outlet, incinerator waste carbon fiber reinforced plastics.
[2] Using the heat generated in the combustion furnace, the waste carbon fiber reinforced plastic is combusted in the external heat furnace, the hot gas generated by the combustion is returned to the combustion furnace, and the waste carbon fiber reinforced plastic remains unburned. A method for incineration of waste carbon fiber reinforced plastic, characterized in that the waste carbon fiber reinforced plastic is re-combusted by putting it into the external heating furnace again.

According to the present invention described above, for example, the waste carbon fiber reinforced plastic is not burned in a combustion furnace such as a cement kiln preheater or a calcining furnace, but burned in an external heating furnace attached to the combustion furnace. Since this system burns waste carbon fiber reinforced plastic using the heat of the furnace, there is no time restriction for burning, and sufficient combustion time can be secured. There is no need to Further, there is no adverse effect such as reducing the dust collection efficiency of the dust collector attached to the incinerator due to the unburned residue of the waste carbon fiber reinforced plastic scattered in the combustion furnace. In other words, the waste carbon fiber reinforced plastic can be incinerated without finely pulverizing and without impairing the function of the dust collector.
In addition, according to the present invention described above, waste carbon fiber reinforced plastic that is hard to burn and has high mechanical strength can be treated in an unlimited amount without being disposed of in landfill, and waste carbon fiber reinforced plastic In the case of a system that returns the hot gas generated during combustion to the combustion furnace, a large amount of waste carbon fiber reinforced plastic can be effectively thermally recycled as an energy source.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram which shows embodiment which implement | achieved the apparatus which incinerates the waste carbon fiber reinforced plastic which concerns on this invention as an incidental apparatus of a cement kiln. It is a notional block diagram of the external heating furnace of the apparatus of FIG.

  Hereinafter, embodiments of an incineration processing apparatus and an incineration processing method for waste carbon fiber reinforced plastic according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an overall embodiment of an incineration processing apparatus for waste carbon fiber reinforced plastic according to the present invention. This apparatus includes an external heating furnace 11 attached to the cement baking apparatus 2. In addition, about the cement kiln 3, the clinker cooler 4, the preheater 5, and the calcining furnace 6 which comprise the cement baking apparatus 2, since it is generally used with the cement manufacturing apparatus, description about these is abbreviate | omitted.

  The external heating furnace 11 is connected to the upright portion 7 of the kiln bottom located between the cement kiln 3 and the calcining furnace 6, and the inside of the external heating furnace 11 communicates with the inside of the upright portion 7. The hot gas (first hot gas) G1 generated in 2 is sent into the external heating furnace 11 through the first hot gas pipe 10.

  As shown in FIG. 2, waste carbon fiber reinforced plastic (CFRP) is fed from the stocker 1 to the charging port 11 a of the external heating furnace 11 and is conveyed through the external heating furnace 11. The size of CFRP at the time of charging may be a size that can enter the external heating furnace 11. However, since the time of incineration treatment becomes longer as it becomes larger, in order to perform stable treatment, it is preferable to adjust the maximum size to be charged, and the maximum side length of the CFRP is equal to the diameter of the external heating furnace. It is preferable to adjust the length to be one half or less, and it is more preferable to adjust the length to be one third or less.

  Hot gas is fed into the external heating furnace 11 from the combustion furnace and heated. In this embodiment, the hot gas (first hot gas) G <b> 1 is supplied from the kiln bottom of the cement kiln 3 through the first hot gas pipe 10. The CFRP placed on the hearth 11b composed of a roller or a transport vehicle (not shown) is incinerated by the first hot gas G1.

  In a preferred embodiment, refractory bricks are disposed on the inner wall of the external heating furnace 11 and a nozzle (not shown) for supplying air or the like for adjusting the temperature and oxygen concentration inside the external heating furnace 11. (Temperature / oxygen concentration adjusting means) is provided.

  Next, the operation of the apparatus having the above configuration will be described with reference to FIGS.

  During the operation of the cement kiln 3, the cement raw material supplied to the preheater 5 is preheated by the preheater 5, calcined in the calcining furnace 6, and then calcined in the cement kiln 3 to generate cement clinker. During operation of the cement kiln 3, the inside of the upright portion 7 is about 900 ° C. to 1100 ° C. Therefore, the hot gas G1 supplied from the upright portion 7 inside the external heating furnace 11 communicating with this temperature region. Can be used to burn CFRP at a temperature of at least about 600 ° C to 900 ° C.

  The hot gas G1 which is the combustion exhaust gas of the cement kiln 3 supplied from the upright portion 7 to the inside of the external heating furnace 11 may have a low oxygen concentration. The CFRP can be burned by increasing the oxygen concentration inside the furnace 11. In addition to adjusting the oxygen concentration, various gases can be supplied for the purpose of adjusting the internal temperature of the external heating furnace 11, for example, oxygen gas, nitrogen gas, water, water vapor, etc. in addition to the above-described atmosphere These may be supplied alone, or two or more of them may be supplied simultaneously. One or more selected from the atmosphere, oxygen gas, nitrogen gas, water and water vapor is supplied from a nozzle which is a temperature / oxygen concentration adjusting means (not shown), and combustion conditions such as the temperature and oxygen concentration inside the external heating furnace 11 are supplied. Make adjustments.

  The temperature of the external heating furnace 11 can be adjusted by the location where the hot gas is extracted, the mixing of the hot gas, or a new heat source may be used. By using this method, it is possible to incinerate CFRP without using a new heat source. As will be shown later in the test examples, the treatment temperature may be 600 ° C. or higher, and the treatment time can be shortened as the treatment temperature increases. The processing time can be adjusted by the temperature of the external heating furnace. By optimizing the temperature and processing time of the external heating furnace, CFRP can be completely incinerated. For example, in the case of 1000 ° C., it can be completely incinerated in about 1 hour.

  The hot gas (second hot gas) G2 generated by the combustion of CFRP inside the external heating furnace 11 is returned to the preheater 5 of the cement baking apparatus 2 through the second hot gas pipe 13, and the amount of heat is It is used for preheating the cement raw material together with the combustion exhaust gas flowing in the preheater 5.

  In addition, by returning the hot gas (second hot gas) G2 generated by the combustion of CFRP to the preheater 5 as described above, CO and hydrocarbon gas contained in the hot gas (second hot gas) G2 Is burned in the calcining furnace 6, the acid gas generated by CFRP-derived chlorine and sulfur is treated with a large amount of CaO contained in the cement raw material, DXNs are decomposed at a high temperature, and then rapidly cooled to recycle DXNs. Synthesis can be suppressed. That is, it is not necessary to provide an exhaust gas treatment device for the external heating furnace 11 in particular, and the existing exhaust gas incineration treatment device for the cement kiln and the preheater can be commonly used.

  CFRP differs in carbon fiber content and shape size. For this reason, in the case of a material having a high heat resistance and a thick plate or block, the carbon fiber may remain unburned. Even if the carbon fibers remain unburned, they are separated and recovered from the exhaust gas, and therefore do not enter the cement baking apparatus 2. Therefore, the dust collection efficiency of an electric dust collector (not shown) attached to the cement baking apparatus 2 is not lowered. The CFRP ash is discharged from the ash discharge port 11c. Unburned carbon fiber is recovered, transported to the charging port 11a using the unburned transporting means 14, and put into the external heating furnace 11 again for complete incineration.

  In the above embodiment, the hot gas is fractionated from the upright portion 7 located between the cement kiln 3 and the calcining furnace 6, but the combustion gas at 600 ° C. to 1200 ° C. can be fractionated. If it exists, it may be fractionated from another location of the cement baking apparatus 2, for example, the exhaust gas of the clinker cooler 4 can be fractionated. Further, the part for returning the hot gas generated in the external heating furnace 11 is not limited to the preheater 5 but may be the calcining furnace 6 or the like. Further, the hot gas generated in the external heating furnace 11 may be used as a heat source such as a drying furnace or a boiler.

  As described above, the incineration processing apparatus and the incineration processing method for waste carbon fiber reinforced plastic according to the present invention have been described in detail with reference to the drawings. Needless to say, the present invention can be implemented as other forms of apparatuses and methods.

Test example

  Hereinafter, although the test example which supports the effect of this invention is described, this invention is not limited at all by this test example.

The CFRP used for the test is obtained by cutting waste CFRP obtained as waste into 8 to 15 mm square using a saw or a grinder. The weight loss rate at 975 ° C. ignition measured according to JIS A 6201 of this CFRP was 99.0%, and the residue rate was 1.0%.
The incineration test method was performed as follows.
25 g of CFRP was put into an external heating furnace (diameter: 30 mm) set at a predetermined temperature, the weight of CFRP that came out of the external heating furnace after a predetermined processing time was measured, and the residue rate after incineration was determined.
The residue rate is calculated by (weight after incineration [g] / 25 [g]) × 100.

Table 1 shows the temperatures, processing times, and weight loss rates of Examples 1 to 4 and Comparative Examples 1 to 4.

(Examples 1 and 2)
In both Examples 1 and 2 in which the temperature of the external heating furnace was 1000 ° C., the incineration residue was powdery, and the residue rate was 0.04%. Considering that there was no fibrous material and the residual rate after ignition at 975 ° C., it can be said that the carbon fiber and the resin were completely incinerated.
(Comparative Examples 1 and 2)
In both Comparative Examples 1 and 2 in which the temperature of the external heating furnace was 1000 ° C., cotton-like carbon fibers could be confirmed in the residue after the incineration treatment, and the residue rates were 10.5% and 1.6%, respectively. From this, it was found that carbon fibers remained unburned in both Comparative Examples 1 and 2.

(Examples 3 and 4)
In Example 3 where the temperature of the external heating furnace was 800 ° C. and Example 4 where the temperature of the external heating furnace was 600 ° C., the incineration residue was powdery, and the residue rates were 0.06% and 0.8%, respectively. It was. Considering that there was no fibrous material and the residual rate after ignition at 975 ° C., it can be said that both of the carbon fibers and the resin were completely incinerated.
(Comparative Examples 3 and 4)
Cotton-like carbon fibers could be confirmed in the residue after the incineration treatment of Comparative Example 3 having an external heating furnace temperature of 800 ° C., and the residue rate was 8.8%. Moreover, the cotton-like carbon fiber can be confirmed to the residue after the incineration process of the comparative example 4 whose external heating furnace temperature is 600 degreeC, and the residue rate was 3.2%. From this, it was found that carbon fibers remained unburned in Comparative Examples 3 and 4.

  As can be seen from Table 1, CFRP can be completely incinerated at a temperature of about 600 ° C. as long as the processing time can be secured.

DESCRIPTION OF SYMBOLS 1 Stocker 2 Cement calciner 3 Cement kiln 4 Clinker cooler 5 Preheater 6 Calciner 7 Upright part 10 1st hot gas piping 11 External heating furnace 11a Input port 11b Hot gas inlet 11c Ash discharge port 13 2nd hot gas Piping 14 Unburned conveying means G1 Hot gas (first hot gas)
G2 hot gas (second hot gas)

Claims (6)

  A combustion furnace, a first hot gas pipe for branching the hot gas (first hot gas) of the combustion furnace from the combustion furnace, and an external heat furnace, wherein the external heat furnace is a waste carbon fiber reinforced plastic. A hot gas inlet connected to the first hot gas pipe, and a transport means for transporting the waste carbon fiber reinforced plastic in an external heating furnace, and the first heat The waste carbon fiber reinforced plastic placed on the conveying means is incinerated by the hot gas supplied through the gas pipe, and the ash of the incinerated waste carbon fiber reinforced plastic is discharged from the ash outlet. Incinerator for waste carbon fiber reinforced plastic.   The waste carbon fiber reinforcement according to claim 1, wherein the combustion furnace includes a cement kiln and a preheater, and the first hot gas pipe branches from an upright portion of a kiln bottom of the cement kiln. Plastic incineration processing equipment.   A second hot gas pipe is provided for returning a hot gas (second hot gas) generated in the external heat furnace when the waste carbon fiber reinforced plastic is incinerated to the combustion furnace. The incineration processing apparatus of waste carbon fiber reinforced plastics of 1.   2. The incineration processing apparatus for waste carbon fiber reinforced plastic according to claim 1, further comprising unburned residue transport means for transporting unburned waste carbon fiber reinforced plastic from the ash discharge port to the input port.   The external heating furnace is provided with temperature / oxygen concentration adjusting means for supplying one or more selected from the air, oxygen gas, nitrogen gas, water and water vapor, and adjusting the temperature and oxygen concentration inside the external heating furnace. The incineration processing apparatus for waste carbon fiber reinforced plastic according to claim 1.   Using the heat generated in the combustion furnace, the waste carbon fiber reinforced plastic is burned in the external heating furnace, the hot gas generated by the combustion is returned to the combustion furnace, and the unburned residue of the waste carbon fiber reinforced plastic is again A method for incineration of waste carbon fiber reinforced plastic, characterized in that it is re-burned by putting it in an external heating furnace.

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