JP2019039103A - Manufacturing apparatus of regenerated carbon fiber and manufacturing method of regenerated carbon fiber - Google Patents

Abstract

To provide a manufacturing apparatus and a manufacturing method for manufacture of a regenerated carbon fiber, capable of manufacturing the regenerated carbon fiber rapidly.SOLUTION: The manufacturing apparatus of a regenerated carbon fiber contains a carbonization pyrolysis furnace 1. The carbonization pyrolysis furnace 1 contains a box-shaped body part 10, a carbonization dry distillation chamber 11 provided inside of the body part 10, a combustion chamber 12 arranged under the carbonization dry distillation chamber 11 and containing a burner 14, a heating chamber 13 provided between the body part 10 and the carbonization dry distillation chamber 11, and a carbonization gas combustion piping 15 for supplying a carbonization gas generated in the carbonization dry distillation chamber 11 to the burner 14, wherein the carbonization dry distillation chamber 11 is maintained under application of pressure. The most desired pressure application condition is 0.2 kPa or over and 15 kPa or under as a gauge pressure.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a manufacturing apparatus and a manufacturing method for manufacturing regenerated carbon fiber using carbon fiber reinforced plastic as a raw material.

  Carbon fiber is lighter than iron and aluminum, has the characteristics of high strength and does not corrode, and is used as a raw material for single fibers or woven fabrics. Carbon fiber is used as a raw material of “carbon fiber reinforced plastic (hereinafter also referred to as CFRP)”.

  CFRP is manufactured by impregnating carbon fiber with an epoxy resin or a polyester resin and curing. Many mill ends are generated in the manufacturing process of CFRP. In particular, when manufacturing large products such as aircraft bodies and automobile parts, a large amount of scrap material is generated. Since carbon fiber is an expensive and versatile material, there is a need for a technology that removes only resin from mill ends and non-standard products, and extracts and reuses carbon fiber.

  The inventors of the present application invented a method for producing a regenerated carbon fiber by pyrolyzing the resin as a method for producing a regenerated carbon fiber by removing the matrix resin of the carbon fiber reinforced plastic, and disclosed in Patent Document 1 . The technology for producing regenerated carbon fiber disclosed in Patent Document 1 is that the matrix resin is removed by two-stage pyrolysis of heating using a batch-type carbonization carbonization furnace and heating using a continuous furnace, and the fiber length is long. A regenerated carbon fiber maintaining the carbon fiber state can be produced. The apparatus and method for producing regenerated carbon fiber of Patent Document 1 are characterized in that steam at 100 ° C. or more and 700 ° C. or less is supplied during heating by a carbonization dry distillation furnace.

  Patent Document 2 discloses a technique for recovering carbon fiber in a state where 68 to 80% of the plastic is removed by treating the carbon fiber reinforced plastic with superheated steam at 800 ° C. or higher. Patent Document 3 discloses a recovery device that includes a heater section that produces superheated steam, an introduction section that introduces the produced steam, and a holding section that holds carbon fiber reinforced plastic.

JP 2013-062219 A JP 2011-122032 A

  The apparatus and method for producing regenerated carbon fiber disclosed in Patent Document 1 is an excellent technique for producing regenerated carbon fiber having a long fiber length using CFRPs having different lengths and thicknesses as raw materials. However, in the technique of Patent Document 1, the heating time of the carbonization dry distillation furnace which is a batch type takes a relatively long time from 2 hours to 24 hours. For this reason, a technique for further shortening the heating time of the carbonization furnace and increasing the production efficiency has been demanded.

  This invention is made | formed in view of the said situation, Comprising: It aims at providing the technique which shortens the heating time of a carbonization-drying furnace compared with the past, and manufactures a reproduction | regeneration carbon fiber efficiently.

  The present invention relates to an apparatus for producing regenerated carbon fiber. The apparatus for producing regenerated carbon fiber of the present invention includes a carbonization furnace. This carbonization furnace includes a box-shaped main body, a carbonization carbonization chamber formed inside the main body, a combustion chamber disposed at the bottom of the carbonization carbonization chamber, and provided with a burner, a main body, and carbonization carbonization. A heating chamber formed between the two chambers, and a dry distillation gas combustion pipe for supplying a dry distillation gas generated in the carbonization dry distillation chamber to the burner. The apparatus for producing regenerated carbon fiber of the present invention is characterized in that the carbonization furnace is controlled in a pressurized state.

  Here, controlling the carbonized carbonization chamber to a pressurized state refers to controlling the pressure inside the carbonization carbonization chamber to be higher than the atmospheric pressure.

In the apparatus for producing regenerated carbon fiber of the present invention, it is preferable to control the pressure in the carbonization chamber to 0.2 to 15 kPa as a gauge pressure.

  In the produced carbon fiber production apparatus of the present invention, the dry distillation gas combustion pipe of the carbonization furnace is provided with a flow control means for dry distillation gas. And it is preferable that a flow control means controls the pressure of a carbonization dry distillation chamber by controlling the flow rate of the dry distillation gas supplied to a burner from a carbonization dry distillation chamber.

  The present invention also provides a method for producing regenerated carbon fiber using carbon fiber reinforced plastic as a raw material. The method for producing regenerated carbon fiber of the present invention includes a step of storing carbon fiber reinforced plastic in a carbonization carbonization chamber of a carbonization carbonization furnace, a carbonization step of heating the carbon fiber reinforced plastic by controlling the carbonization carbonization chamber to a pressurized state, It is characterized by providing.

  The apparatus and method for producing a regenerated carbon fiber according to the present invention produces a regenerated carbon fiber having a quality equivalent to that of the conventional carbon fiber in a shorter time by placing the carbonization carbonization chamber of the carbonization carbonization chamber of the carbonization furnace in a pressurized state. can do. In particular, even a thick carbon fiber reinforced plastic can be removed more rapidly by heating in a pressurized state.

  The apparatus for producing regenerated carbon fiber of the present invention is capable of producing regenerated carbon fiber by stably carbonizing and carbonizing carbon fiber reinforced plastic by controlling the carbonization carbonization chamber to a gauge pressure of 0.2 kPa to 15 kPa. it can.

  The apparatus and method for producing regenerated carbon fiber of the present invention can reduce the heating time in the carbonization carbonization chamber, thereby reducing the fuel used for heating and producing regenerated carbon fiber at a lower cost.

It is a longitudinal cross-sectional view which shows the outline | summary of the carbonization dry distillation furnace 1 which is a part of the manufacturing apparatus of the regenerated carbon fiber of this invention. It is a figure which shows the time-dependent change of the temperature in the carbonization carbonization furnace 1 when the gauge pressure of the carbonization carbonization chamber 10 of this invention is controlled to 4 kPa. It is a figure which shows the time-dependent change of the temperature in the carbonization carbonization furnace 1 when the gauge pressure of the carbonization carbonization chamber 10 of this invention is controlled to 0.4 kPa. It is a figure which shows the time-dependent change of the temperature in the carbonization carbonization furnace 1 when the gauge pressure of the carbonization carbonization chamber 10 of this invention is controlled to 15 kPa.

  Hereinafter, the structure of a production apparatus for regenerated carbon fiber according to the present invention and a preferred embodiment of a method for producing regenerated carbon fiber will be described with reference to the drawings.

[Recycled carbon fiber production equipment]
The apparatus for producing regenerated carbon fiber of the present invention includes a carbonization carbonization furnace 1. A longitudinal sectional view of the carbonization furnace 1 of the present embodiment is shown in FIG. The carbonization furnace 1 includes a box-shaped main body 10. Inside the main body 10, a carbonized carbonization chamber 11 is formed in which heat treatment is performed for containing a raw material CFRP and producing regenerated carbon fiber. A combustion chamber 12 is formed below the carbonization dry distillation chamber 11. A heating chamber 13 is formed in the space between the main body 10 and the carbonization carbonization chamber 11.

  Both the main body 10 and the outer wall of the carbonized carbonization chamber 11 are made of heat-resistant metal. An opening is provided in front of the main body 10, and the position of this opening is aligned with the position of the opening of the carbonization carbonization chamber 11. The opening of the main body 10 and the opening of the carbonized carbonization chamber 11 can be simultaneously sealed by closing one sealing door (not shown), and the inside of the carbonized carbonization chamber 11 is heated in an oxygen-free state. Is possible.

  The combustion chamber 12 includes a burner 14, and the heating chamber 13 and the carbonization carbonization chamber 11 can be heated by the combustion of the burner 14. A dry distillation gas combustion pipe 15 that communicates the combustion chamber 12 with the inside of the carbonization dry distillation chamber 11 is provided, and a dry distillation gas generated from CFRI during the production of regenerated carbon fiber can be introduced into the combustion chamber 12. A blower 16 serving as a blowing means is disposed in an opening of the dry distillation gas fuel pipe 15 on the combustion chamber 12 side.

  The dry distillation gas fuel pipe 15 includes a flow rate control means 20. The flow rate control means 20 in this embodiment is a valve. The flow rate control means 20 controls the pressure of the carbonized carbonization chamber 11 by controlling the flow rate of the carbonization gas introduced from the carbonized carbonization chamber 11 into the combustion chamber 12. If the opening amount of the valve is reduced, more of the carbonization gas stays in the carbonization chamber 11 and the pressure in the carbonization chamber 11 can be increased. On the contrary, if the opening amount of the valve is increased, the pressure in the carbonization dry distillation chamber 11 can be lowered. A pressure gauge 30 is attached to the pressure door of the carbonized carbonization chamber 11 to measure the pressure inside the carbonization carbonization chamber 11. Based on the measurement value of the pressure gauge 30, the flow rate control of the dry distillation gas by the flow rate control means 20 is performed.

  Although not essential, the carbonization carbonization furnace 1 of the present invention includes means for supplying superheated steam to the carbonization carbonization chamber 11. The carbonization dry distillation furnace 1 according to the present embodiment includes an external boiler 17, a superheated steam generator 18 disposed in the heating chamber 13, and the interior of the carbonization dry distillation chamber 11 from the external boiler 17 via the superheated steam generator 18. The superheated steam is supplied by the steam pipe 19 leading to For example, a heat exchanger can be used as the superheated steam generator 18. The external boiler 17 preheats the steam and supplies it to the superheated steam generator 18 in the heating chamber 13, and this steam is supplied to the carbonization dry distillation chamber 11 as superheated steam by the superheated steam generator 18. The supply of superheated steam accelerates the decomposition of the CFRP resin. In particular, when superheated steam is supplied, the superheated steam penetrates deeply through the thick CFRP in the pressurized state, so that it is possible to remove the plastic quickly and uniformly.

  The carbonization furnace 1 is provided with a plurality of temperature sensors, and periodically measures the temperature. As a preferred embodiment of the arrangement of the temperature sensors, temperature sensors 23, 24, 25, and 26 are arranged in the combustion chamber 12, the side wall of the heating chamber 13, and the left and right side walls of the carbonization carbonization chamber 11, respectively. Measure the temperature regularly. The carbonization furnace 1 includes a hot air discharge duct 21 that communicates with the combustion chamber 12 and the heating chamber 13 through branch paths. The hot air discharge duct 21 is provided with a damper 22 in each passage between the combustion chamber 12 and the heating chamber 13. Based on the measurement results of the temperature sensors 23, 24, 25, and 26, the temperature of the carbonization dry distillation chamber 11 can be controlled by controlling the opening / closing amount of the damper 22.

[Production method of regenerated carbon fiber]
A method for producing regenerated carbon fiber using carbon fiber reinforced plastic (CFRP) as a raw material by using the carbonized carbonization furnace 1 of the present invention includes a step of storing carbon fiber reinforced plastic in the carbonized carbonization chamber 11, and a carbonization carbonization chamber 11. And a carbonization step of heating the carbon fiber reinforced plastic by controlling the pressure at 0.2 to 15 kPa as a gauge pressure.

  CFRP is accommodated in a heat-resistant shelf (not shown) provided in the carbonized carbonization chamber 11. By sealing the carbonized carbonization chamber 11 with a sealing door and heating the whole, it is possible to heat the CFRP while maintaining the inside of the carbonization carbonization chamber 11 in an oxygen-free state. The carbonization dry distillation chamber 11 is heated by burning the burner 14 of the combustion chamber 12, supplying radiant heat from the combustion chamber 12 to the heating chamber 13, and heating the carbonization dry distillation chamber 11 with this radiant heat.

  The raw material CFRP heated to 200 ° C. or more in an oxygen-free state generates a hydrocarbon gas such as methane or benzene, which is a combustible gas, by thermally decomposing a resin as a matrix component. The gas containing the hydrocarbon derived from the resin component is a dry distillation gas. The generated dry distillation gas passes from the carbonization dry distillation chamber 11 through the dry distillation gas combustion pipe 15, is mixed with air by the blower 16, and burns in the combustion chamber 12. The combustion heat of the dry distillation gas is used for raising the temperature and maintaining the temperature of the carbonization dry distillation chamber 11.

  By controlling the flow rate of the dry distillation gas flowing out from the carbonization dry distillation chamber 11 to the combustion chamber 12 by the flow rate control means 20 provided in the dry distillation gas combustion pipe 15, the pressure of the carbonization dry distillation chamber 11 can be controlled. Become. If the valve which is the flow rate control means 20 is greatly opened to increase the flow rate, the pressure in the carbonization chamber 11 can be lowered. By closing the valve that is the flow rate control means 20 and reducing the flow rate, the pressure in the carbonization chamber 11 can be increased. By controlling the pressure in the carbonized carbonization chamber 11 to 0.2 kPa or more and 15 kPa as a gauge pressure, the CFRP resin component is decomposed more rapidly than the case where carbonization is performed under atmospheric pressure conditions to produce regenerated carbon fiber. can do.

  In the apparatus for producing regenerated carbon fiber of the present invention, it has been difficult to maintain the pressure in the carbonized carbonization chamber 11 at a pressure of less than 0.2 kPa as a gauge pressure. In addition, when the regenerated carbon fiber was produced with the target pressure set to 0.1 kPa as the gauge pressure, the heating time equivalent to the case of heating at atmospheric pressure was required, and the effect of shortening the heating time was not recognized. .

  In the apparatus for producing regenerated carbon fiber of the present invention, when the carbonization carbonization chamber 11 is heated while maintaining the pressure of the carbonization carbonization chamber higher than 15 kPa as a gauge pressure, there is a problem that the carbonization carbonization chamber 11 expands and it is difficult to maintain the shape. It was. On the other hand, under the pressurizing conditions of 0.2 kPa or more and 15 kPa or less in the examples described below, it was possible to produce stable regenerated carbon fibers.

  Hereinafter, an example in which the dry distillation step is performed with the target pressure of the carbonization chamber 11 set to 4 kPa as a gauge pressure is shown as Example 1. An example in which the dry distillation step was performed with the target pressure of the carbonization chamber 11 set to 0.2 kPa as a gauge pressure is shown as Example 2. An example in which the dry distillation step was performed with the target pressure of the carbonization chamber 11 set to 15 kPa as a gauge pressure is shown as Example 3.

[Example 1]
FIG. 2 shows measured values of elapsed time, temperature, and pressure in the dry distillation process in which 606 kg of regenerated carbon fiber was produced using 800 kg of CFRP as a raw material. In the present example, the target pressure of the carbonization chamber 11 was set to 4 kPa as a gauge pressure, and the target temperature was set to 200 ° C. to 600 ° C.

  In this example, the heating time of 5 hours and 20 minutes was required for the production of the regenerated carbon fiber. With the start of the carbonization process, the carbonization chamber 11 is heated by the combustion of the burner 14 supplied with fuel. When the carbonization chamber 11 reaches a sufficiently high temperature, these dry distillation gases reach the combustion chamber 12 via the dry distillation gas combustion pipe 15 and burn, thereby contributing to maintaining the temperature of the carbonization furnace 1. By controlling the flow rate control means 20 of the dry distillation gas combustion pipe 15, that is, the valve opening / closing amount, the pressure in the carbonization dry distillation chamber 11 could be controlled in the range of 1 kPa to 4 kpa for 5 hours and 20 minutes. Thereafter, 606 kg of recycled carbon fiber was produced by cooling for 17 hours. The product yield was 75.8%.

  In this example, 98 liters of kerosene was consumed in the combustion chamber 12 for the production of regenerated carbon fiber, and 43 liters of kerosene was consumed in the external boiler 17 for supplying superheated steam to the carbonization carbonization chamber 11. . The total consumption of kerosene was 141 liters.

[Example 2]
FIG. 3 shows the temperature and pressure conditions in the carbonization process when the regenerated carbon fiber is produced by setting the pressure in the carbonization carbonization chamber 11 lower. In this example, the target pressure of the carbonization chamber 11 was set to 0.2 kPa as a gauge pressure, and the target temperature was 200 to 600 ° C. as in Example 1. Also in the present example, a regenerated carbon fiber of 608 kg of approximately the same amount as in Example 1 was produced using 800 kg of CFRP as a raw material.

  In this example, the production of the regenerated carbon fiber required 6 hours of heating time. In the meantime, the pressure in the carbonization chamber 11 was 0.6 kpa at maximum with a temporary change in the amount of generated carbonization gas, but could be controlled in the range of about 0.2 to 0.4 kPa. Then, 608 kg of recycled carbon fiber was produced by cooling for 16 hours. The product yield was 76.0%.

  In this example, 210 liters of kerosene was consumed in the combustion chamber 12 for the production of regenerated carbon fiber, and 54 liters of kerosene was consumed in the external boiler 17 for supplying superheated steam to the carbonization distillation chamber 11. . The total consumption of kerosene was 264 liters.

[Example 3]
FIG. 4 shows the temperature and pressure conditions in the carbonization process when the target pressure in the carbonization chamber 11 is set to 15 kPa as the gauge pressure. Also in this example, 607 Kg of regenerated carbon fiber was manufactured in the same amount as in Example 1 using 800 kg of CFRP as a raw material.

  In this example, the heating time of 5 hours and 5 minutes was required for the production of the regenerated carbon fiber. Although the target pressure was set to 15 kPa, the gauge pressure actually measured in the carbonization chamber 11 was approximately 9 to 15 kPa from the start of heating until 3 hours passed. The heating time was in the range of about 1 to 8 kPa between 3 hours and 5 hours. Thereafter, 607 kg of regenerated carbon fiber was produced by cooling for 17 hours. The product yield was 75.8%.

  In this example, 74 liters of kerosene was consumed in the combustion chamber 12 for the production of regenerated carbon fiber, and 40 liters of kerosene was consumed in the external boiler 17 for supplying superheated steam to the carbonization distillation chamber 11. . The total consumption of kerosene was 114 liters.

  Between Examples 1 to 3, there was no difference in strength, defibration degree, and other qualities of the regenerated carbon fiber. From this, it became clear that a regenerated carbon fiber of the same quality can be produced in a shorter time by maintaining the pressure higher. On the other hand, in Example 3, even when the target pressure in the carbonization chamber 11 was set to 15 kPa, the pressure gradually decreased particularly in the latter half of the heating process, and therefore, when the target pressure was set high, the entire heating process was performed. It was found that maintaining the pressure was difficult and the effect of shortening the reaction time was limited.

[Comparative example]
In order to produce 600 kg of regenerated carbon fiber from 800 kg of CFRP when all of the carbonized carbonization chamber 11 is maintained under the same conditions as the atmospheric pressure except that the flow rate control means 20 is not used. Required a 6-hour 20-minute dry distillation step. As shown in Examples 1 to 3, the effect of the method for producing regenerated carbon fiber with the carbonization chamber 1 in a pressurized state is clear.

  The present invention has been described with reference to preferred embodiments and examples. However, the present invention is not limited to these exemplifications, and various improvements and design changes can be made without departing from the scope of the present invention. Is possible. For example, in order to control the pressurizing condition, in addition to controlling the flow rate of dry distillation gas by the flow rate control means 20, the supply amount of heated steam is controlled, or a plurality of dry distillation gas combustion pipes 15 are provided to control the opening and closing thereof. The method can be used.

DESCRIPTION OF SYMBOLS 1 Carbonization distillation furnace 11 Carbonization distillation chamber 12 Combustion chamber 13 Heating chamber 14 Burner 15 Dry distillation gas combustion piping 16 Blower 17 External boiler 18 Superheated steam generation means 19 Steam piping 20 Flow control means 21 Hot air discharge ducts 23, 24, 25, 26 Temperature measurement sensor 30 Pressure gauge

Claims (4)

An apparatus for producing regenerated carbon fiber equipped with a carbonization furnace,
The carbonization furnace is
A box-shaped body,
A carbonization chamber formed inside the main body,
A combustion chamber disposed below the carbonization carbonization chamber and provided with a burner;
A heating chamber formed between the main body and the carbonization carbonization chamber;
Dry distillation gas combustion piping for supplying dry burner gas generated in the carbonization dry distillation chamber to the burner;
With
An apparatus for producing regenerated carbon fiber, wherein the carbonized carbonization chamber is controlled in a pressurized state.   2. The apparatus for producing regenerated carbon fiber according to claim 1, wherein the pressure in the carbonized carbonization chamber is controlled to be 0.2 kPa or more and 15 kPa or less as a gauge pressure. The dry distillation gas combustion pipe is provided with a dry distillation gas flow rate control means,
3. The regenerated carbon fiber according to claim 1, wherein the flow rate control unit controls the pressure of the carbonized carbonization chamber by controlling the flow rate of the carbonization gas supplied to the burner from the carbonization carbonization chamber. manufacturing device. A method for producing regenerated carbon fiber using carbon fiber reinforced plastic as a raw material,
Containing carbon fiber reinforced plastic in the carbonization chamber of the carbonization furnace;
A carbonization step of heating the carbon fiber reinforced plastic by controlling the carbonization chamber to a pressurized state;
A method for producing a regenerated carbon fiber, comprising:

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