JP4279925B2 - Horizontal heat treatment furnace and heat treatment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a horizontal heat treatment furnace and a heat treatment method for continuously heat-treating a fiber sheet, and more specifically, in the flameproofing treatment when producing carbon fiber, the gas in the furnace leaks to the outside. The present invention relates to a horizontal heat treatment furnace and a heat treatment method that can be completely prevented.
[0002]
[Prior art]
Carbon fibers manufactured using conventional acrylic fibers as raw materials can have extremely high performance such as tensile strength of 500 kg / mm ² or more and elongation of 2% or more. Application development as a material is being actively promoted. When carbon fibers are produced using such acrylic fibers as starting materials, it is first necessary to flame-treat the acrylic fibers in an oxidizing atmosphere at 200 to 350 ° C. This flameproofing method is disclosed in, for example, Japanese Patent Laid-Open No. 2-139425.
[0003]
According to the heat treatment method disclosed in the publication, hot air is allowed to flow in a direction perpendicular to the traveling direction with respect to yarns made of acrylic fibers traveling in multiple stages in a heat treatment furnace in an oxidizing atmosphere. The flameproofing treatment is applied. The heat treatment furnace is divided into at least four zones, temperature control is performed in each zone, the temperature is gradually increased, and the velocity of the hot air is set to 0.4 m / s or more and 1.2 m / s or less. This avoids troubles such as cutting of the running yarn and shortens the processing time.
[0004]
By the way, a decomposition gas such as cyanide, ammonia and carbon monoxide is generated in the heat treatment furnace by the oxidation reaction in the flameproofing treatment. Note that when the yarn enters and exits the heat treatment furnace, the yarn heat treatment furnace is naturally provided with a yarn lead-out inlet, and therefore the gas in the heat treatment furnace leaks out of the furnace from the lead-out inlet. Strict sealing chambers are provided so that there is no danger.
[0005]
In view of this, Japanese Patent Application Laid-Open Nos. 62-228865 and 62-228866 disclose a horizontal heat treatment furnace for carbon fibers having means for preventing gas leakage in the processing chamber. In the heat treatment furnaces disclosed in the above publications, a large number of fiber sheets arranged in a sheet form travel in parallel in a heat treatment chamber in an oxidizing atmosphere and blow hot air in parallel with the travel direction. It is attached with a flameproofing treatment. There are provided a plurality of slit lead-out inlets on both wall surfaces of the heat treatment chamber facing each other, and seal chambers are provided adjacent to both wall surfaces where the lead-out inlets are formed, so that the heat treatment is performed. The gas in the processing chamber is prevented from leaking to the outside directly from the outlet port formed in the chamber.
[0006]
In the heat treatment furnace disclosed in Japanese Patent Application Laid-Open No. 62-228865, two partition plates are horizontally arranged in the heat treatment chamber, and the heat treatment chamber is divided into three upper and lower portions, thereby performing the same heat treatment. The temperature distribution at the top and bottom of the chamber is eliminated, and the yarn can be subjected to uniform heat treatment. In addition, the seal chambers formed on both sides are also provided with a plurality of slit lead-out inlets each having a slit shape, but both the seal chambers are further provided with a single exhaust port to leak from the heat treatment chamber. Since the toxic gas is actively exhausted, the toxic gas does not leak from the yarn outlet. The gas discharged from the exhaust port is discharged into the outside air after being subjected to combustion processing in the gas processing section.
[0007]
Furthermore, in the heat treatment furnace disclosed in Japanese Patent Application Laid-Open No. 62-228866, two partition plates are horizontally arranged in each seal chamber on both sides, and the seal chamber is divided into three upper and lower portions. ing. The seal chamber is provided with an exhaust port for each partitioned part to positively exhaust the gas leaked from the heat treatment chamber and prevent gas leakage to the outside from the yarn outlet inlet formed in the seal chamber. is doing. Each exhaust port formed in the seal chamber is exhausted by a single exhaust fan, and the gas is combusted in a common gas processing unit.
[0008]
[Problems to be solved by the invention]
However, as in the heat treatment furnace disclosed in the above-mentioned Japanese Patent Application Laid-Open Nos. 62-228865 and 62-228866, flameproofing treatment is performed by blowing hot air parallel to the running direction of the yarn. Further, since the flow direction of the hot air faces the yarn outlet, the amount of gas including gas leaking from the heat treatment chamber to the seal chamber increases, and accordingly, the amount of exhaust from the exhaust port of the seal chamber And a large amount of gas must be combusted.
[0009]
The present invention has been made to solve such problems, and completely prevents leakage of toxic gas generated in the heat treatment chamber to the outside air without requiring a particularly large facility, and in the heat treatment chamber. It is an object of the present invention to provide a horizontal heat treatment furnace and a heat treatment method that can easily maintain a desired heating temperature and can reduce the amount of toxic gas that requires treatment.
[0010]
[Means for Solving the Problems]
In order to solve this problem, the present invention has a first lead-out entrance for a fiber sheet having a multi-stage slit shape in the vertical direction of both opposing wall surfaces, and the fiber sheet travels in parallel with the multi-stage. A horizontal heat treatment furnace comprising a heat treatment chamber and a seal chamber having a second outlet for the fiber sheet, which is provided in parallel on both wall surfaces and has a multistage slit shape in the vertical direction, on the outer wall surface,
[0011]
The heat treatment chamber includes a hot air circulation facility having a hot air introduction portion for blowing hot air substantially parallel to the traveling direction of the fiber sheet, and a hot air discharge portion for discharging the hot air,
[0012]
Each seal chamber is formed with at least one exhaust port,
The exhaust port of the seal chamber on the hot air introduction part side and the exhaust port of the seal chamber on the hot air discharge part side have an independent exhaust mechanism and an exhaust adjustment mechanism, respectively.
The pressure in the seal chamber on the hot air introduction portion side where hot air is blown is lower than the pressure on the hot air introduction portion side in the heat treatment chamber, and the pressure in the seal chamber on the hot air discharge portion side that discharges hot air is the pressure on the hot air discharge portion side in the heat treatment chamber. The main gist is a horizontal heat treatment furnace characterized in that it is higher and the pressure is adjusted .
[0013]
Here, the fiber sheet refers to a sheet in which a large number of fibers are arranged, a sheet array, a fiber woven or knitted fabric, a nonwoven fabric, and the like.
[0014]
Further, as the exhaust adjustment mechanism, the internal pressure of the seal chamber on the hot air introduction part side, the internal pressure of the seal chamber on the hot air discharge part side, and the internal pressure of the heat treatment chamber are usually compared. In order to automate this, a means for detecting a change in internal pressure and a control unit for adjusting the exhaust amount of the exhaust mechanism by a detection signal from the detection means may be provided.
[0015]
In general, the pressure difference between the pressure inside the heat treatment furnace and the pressure outside the furnace changes in the height direction of the furnace due to the influence of the buoyancy difference inside and outside the heat treatment furnace caused by the difference in gas temperature. That is, the pressure difference in the furnace is higher in the upper part of the furnace than in the furnace, and the pressure in the furnace is lower in the lower part of the furnace than in the furnace.
[0016]
Therefore, in a heat treatment furnace having no conventional seal chamber, hot air in the furnace is likely to leak out from the fiber sheet outlet formed at the top of the heat treatment furnace, while the heat treatment furnace The outside air tends to flow into the heat treatment furnace from the fiber sheet outlet formed in the lower part.
[0017]
However, since the heat treatment furnace of the present invention having the above-described configuration includes the seal chamber, the pressure in the seal chamber can be made smaller than the pressure in the heat treatment chamber. Inflow of outside air into the heat treatment chamber due to fluctuations can be prevented, and the temperature change of the heat treatment can be made extremely small.
[0018]
Further, at least one exhaust port is formed in each seal chamber, and the exhaust port of the seal chamber on the hot air introduction unit side and the exhaust port of the seal chamber on the hot air discharge unit side are independent exhaust mechanisms, respectively. Since the exhaust adjustment mechanism is provided, the exhaust amount can be set independently in each seal chamber, and the pressure in each seal chamber is adjusted appropriately. Therefore, the pressure difference between the heat treatment chamber and the seal chamber can be individually controlled, and the inflow of outside air into the heat treatment chamber due to the influence of the buoyancy difference between the inside and outside of the heat treatment chamber as described above, and excessive hot air from the heat treatment chamber It was possible to control the outflow, and succeeded in making a heat treatment furnace with an unprecedented temperature uniformity.
[0019]
In general, if the amount of exhaust from the exhaust port is increased, it is possible to prevent the gas in the heat treatment chamber from leaking out, but this also increases the outflow of heat from the heat treatment chamber, thereby increasing the temperature in the heat treatment chamber. It tends to cause a decrease, which is not preferable in terms of temperature control. In addition, the amount of outflow gas that is subjected to combustion processing also increases.
[0020]
Therefore, the pressure in the seal chamber on the hot air introduction part side for blowing hot air, the pressure in the seal chamber on the hot air discharge part side for discharging hot air, the pressure on the hot air introduction part side in the heat treatment chamber, and the pressure on the hot air discharge part side in the heat treatment chamber are separated. It is preferable that the pressure in the seal chamber on the hot air introduction portion side for blowing hot air is lower than the pressure on the hot air introduction portion side in the heat treatment chamber, and the pressure in the seal chamber on the hot air discharge portion side for discharging hot air is It is necessary that the pressure is higher than the pressure on the hot air discharge section side in the heat treatment chamber and the pressure is adjusted .
[0021]
The sealing chamber is divided into upper and lower parts by at least one partition plate, and at least one exhaust port is formed in each of the divided sealing chambers. The inflow of outside air into the heat treatment chamber due to the influence of the buoyancy difference and the excessive outflow of hot air from the heat treatment chamber can be controlled, and the exhaust amount can be further reduced, which is preferable.
[0022]
Since the internal pressure of the seal chamber can be controlled more finely, the seal chamber is partitioned vertically by a partition plate for each stage of the fiber sheet, and at least one exhaust port is formed in each seal chamber. The above horizontal heat treatment furnace is more preferable.
[0023]
Also, if the heat treatment chamber is partitioned by a partition plate for each stage on which the fiber sheet travels, the flow of outside air into the heat treatment chamber due to the influence of the buoyancy difference between the inside and outside of the heat treatment chamber as described above, It is preferable because excessive outflow of hot air from the heat treatment chamber can be suppressed to a lower level.
[0024]
Furthermore, the present invention is a carbon fiber heat treatment method in which a precursor, which is a raw material of carbon fiber, is heat-treated in the horizontal heat treatment furnace described above, and the pressure in the seal chamber on the hot air introduction portion side into which hot air is blown is set in the hot air introduction portion in the heat treatment chamber. Other main components are 0.3 to 5 Pa lower than the pressure on the side, and the pressure in the seal chamber on the hot air discharge part side for discharging hot air is 0.3 to 5 Pa higher than the pressure on the hot air discharge part side in the heat treatment chamber It is said.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a schematic view of a horizontal heat treatment furnace for producing carbon fibers, which is a typical embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line BB ′ in the heat treatment furnace. In these drawings, arrows indicate the flow of hot air.
[0027]
In the heat treatment chamber 2 of the horizontal heat treatment furnace 1 according to the present embodiment, the first lead-in inlet 3 for the fiber sheet having a three-stage slit shape in the vertical direction is provided on the left and right opposing wall surfaces 2a and 2b in FIG. -1, 3-2 and 3-3 are formed. Sealing chambers 4, 4 are arranged side by side on the left and right wall surfaces 2 a, 2 b of the heat treatment chamber 2, and on the outer wall surfaces 4 a, 4 b of the seal chamber 4, as in the heat treatment chamber 2, three steps in the vertical direction. The second lead-out inlets 5-1, 5-2 and 5-3 of the fiber sheet having a slit shape are formed.
[0028]
The upper and lower opening dimensions of the first and second outlets 3 and 5 formed in the heat treatment chamber 2 and the seal chamber 4 can pass through the fiber sheet without contacting the outlets 3 and 5. The narrowest possible range is preferable. From this point, the outlet port is preferably a slit whose opening size can be adjusted in the vertical direction.
[0029]
Further, rollers 6 and 6 are arranged outside the left and right seal chambers 4 and 4, respectively. The fiber sheet A to be heat-treated in the heat treatment furnace 1 is formed by arranging a large number of yarns in a horizontal direction in the form of a sheet as shown in FIG. 2, and is formed at the top of the left seal chamber 4. The fiber is introduced into the processing furnace 1 through the fiber lead-in inlet 5-1. The fiber sheet A continuously travels in parallel in three stages in the seal chamber 4 and the heat treatment chamber 3 while being wound around the roller 6, and the fiber outlet 5 formed at the lowermost portion of the right seal chamber 4. -3 to the outside of the processing furnace 1.
[0030]
The heat treatment chamber 2 has hot air introduction portions 2c for blowing hot air in the upper and lower directions through which the fiber sheet passes and in parallel with the traveling direction of the fiber sheet, and hot air for discharging the hot air in the upper and lower directions through which the fiber sheet passes. A discharge portion 2d is provided, and hot air is fed in a direction substantially parallel to the traveling direction of the fiber sheet A. As shown in FIG. 2, the hot air circulation facility further includes a hot air heater 10 installed outside the heat treatment chamber 2, a fan 11, and a duct 12 for connecting the hot air discharge part 2d and the hot air introduction part 2c. It has. An intake port 13 and an exhaust port 14 are also provided in the heat treatment chamber 4 to purify the gas inside the heat treatment chamber 2.
[0031]
Exhaust ports 8a are formed in the seal chambers 4 and 4, respectively. The upper and lower exhaust ports 8 a are forcibly exhausted by independent exhaust fans 9 a arranged outside the heat treatment furnace 1.
[0032]
The difference ΔP _{b, 1} between the internal pressure P _{b, 1} of the seal chamber 4b on the hot air introduction portion 2c side and the internal pressure P ′ _{b, 1} of the heat treatment chamber 2 on the hot air introduction portion 2c side and the seal on the hot air discharge portion 2d side The difference ΔP _{a, 1} between the internal pressure P _{a, 1 of the} chamber 4a and the internal pressure P ′ _{a, 1} of the heat treatment chamber 2 on the hot air introduction part 2c side can be adjusted by an independent exhaust fan 9a. Here, P _{a, x} represents the internal pressure of the x-stage seal chamber 4a from the top of the hot air discharge part 2d side, and P _{b, x} represents the x-stage seal chamber 4b from the top of the hot air introduction part 2c side. Indicates internal pressure. P ′ _{a, x} indicates the internal pressure of the heat treatment chamber 2 at the x-th stage from the top side of the hot air discharge section 2d, and P ′ _{b, x} indicates the heat treatment chamber 2 at the x-stage from the top side of the hot air introduction section 2c. The internal pressure of is shown.
[0033]
In the above-described embodiment, the fiber sheet A is traveled in three stages for the sake of simplification. However, in an actual heat treatment furnace, in order to increase heat treatment efficiency, usually, The fiber sheet is run in several to several tens of steps. It is also possible to provide a large number of the partition plates and further to provide the partition plates for each stage so as to partition all stages.
[0034]
FIG. 3 shows a typical embodiment of the present invention, and is a schematic view of a horizontal heat treatment furnace for producing carbon fibers in which the seal chambers 4 and 4 and the heat treatment chamber 2 are partitioned by partition plates 7 and 15. In this drawing, the arrows indicate the flow of hot air.
[0035]
The heat treatment chamber 2 of the horizontal heat treatment furnace 1 according to the present embodiment shown in FIG. 3 is partitioned by a partition plate 15 for each fiber sheet step, and the inside of the seal chambers 4 and 4 is a fiber sheet step. Each is divided by a partition plate 7, and exhaust ports 8a, 8b, and 8c are formed in the partitioned seal chamber 4 respectively. The upper and lower exhaust ports 8a, 8b, 8c are forcibly exhausted by independent exhaust fans 9a, 9b, 9c arranged outside the heat treatment furnace 1, respectively.
[0036]
The internal pressures P _{b, 1} , P _{b, 2} , P _{b, 3} of the seal chamber 4b on the hot air introduction part 2c side and the internal pressures P _{a, 1} , P _{a, 2} of the seal chamber 4a on the hot air discharge part 2d side, Pa _{, 3} can be adjusted by independent exhaust fans 9a, 9b, 9c. Here, P _{a, x} represents the internal pressure of the x-stage seal chamber 4a from the top of the hot air discharge part 2d side, and P _{b, x} represents the x-stage seal chamber 4b from the top of the hot air introduction part 2c side. Indicates internal pressure.
[0037]
Hereinafter, as shown in FIG. 3, the heat treatment chamber is partitioned by a partition plate for each step of the fiber sheet, and the seal chamber is also partitioned by a partition plate for each step of the fiber sheet. A method for performing heat treatment using a heat treatment furnace that travels in three stages will be described with reference to examples and comparative examples.
[0038]
[Example 1]
In the heat treatment furnace, the step interval, that is, the distance between the fiber sheet outlets, is set to 200 mm, and the slit-like outlet has the heat treatment shown in FIG. 3 having a slit width of 400 mm and a slit height of 15 mm. . The flow coefficient α was 0.9. In the heat treatment furnace, the heat treatment chamber temperature was set to 240 ° C., the seal chamber upper temperature was set to 100 ° C., and the heat treatment furnace outside temperature was 20 ° C.
[0039]
The internal pressure of the seal chamber on the hot air introduction part side is P _{b, 1} = −3.6 Pa, P _{b, 2} = −4.5 Pa, P _{b, 3} = −6.6 Pa, inside the heat treatment chamber on the hot air introduction part side The pressures are P ′ _{b, 1} = −2.9 Pa, P ′ _{b, 2} = −3.4 Pa, P ′ _{b, 3} = −3.9 Pa, that is, the internal pressure of the heat treatment chamber and the internal pressure of the seal chamber The displacement was adjusted so that the differences ΔP _{b, 1} = 0.7 Pa, ΔP _{b, 2} = 1.1 Pa, ΔP _{b, 3} = 2.5 Pa.
[0040]
And, the internal pressure of the seal chamber on the hot air discharge part side is Pa _{, 1} = 0 Pa, Pa, ₂ = 0 Pa, Pa, ₃ = −0.2 Pa, and the internal pressure of the heat treatment chamber on the hot air discharge part side is P ′. _{a, 1} = −0.5 Pa, P ′ _{a, 2} = −1.0 Pa, P ′ _{a, 3} = −1.2 Pa, ie, the difference ΔP _b, between the internal pressure of the heat treatment chamber and the internal pressure of the seal chamber _The displacement was adjusted so that ₁ = 0.5 Pa, ΔP _{b, 2} = 1.0 Pa, ΔP _{b, 3} = 1.0 Pa. A digital manometer manufactured by Okano Seisakusho was used for the measurement of the pressure difference.
[0041]
As a result, no leak of gas in the furnace from the seal chamber to the work environment was observed.
In addition, the cyan gas concentration of the exhaust gas from the hot air discharge part side seal chamber exhaust port was measured by a cyan detector, but was not detected. Furthermore, the temperature variation in the width direction at the hot air introduction portion 2c was 3 ° C.
[0042]
【The invention's effect】
According to the present invention, it is easy to completely prevent leakage of toxic gas generated in the heat treatment chamber to the outside air and maintain a desired heating temperature in the heat treatment chamber without requiring a particularly large facility. It is.
[0043]
[Brief description of the drawings]
FIG. 1 is a schematic view showing the structure of a horizontal heat treatment furnace for producing carbon fiber which is a preferred embodiment of the present invention.
FIG. 2 is a schematic view of a hot air circulation facility in the heat treatment furnace (cross-sectional view taken along the line BB ′ of the horizontal heat treatment furnace in FIG. 1).
FIG. 3 is a schematic view showing the structure of a horizontal heat treatment furnace for producing carbon fiber which is a preferred embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Heat processing furnace 2 Heat processing chamber 2a, 2b Wall surface 2c Hot-air introduction part 2d Hot-air discharge part 3 Fiber sheet extraction inlet 4 Seal chamber 5 Fiber sheet extraction inlet 6 Roller 7 Partition plate 8a, 8b Exhaust port 9a, 9b Exhaust fan 10 Hot air Heater 11 Fan 12 Duct 13 Intake port 14 Exhaust port 15 Heat treatment room partition plate A Fiber sheet

Claims (5)

There are first lead-in entrances for the fiber sheet having a multi-stage slit shape in the vertical direction of both opposing wall surfaces, and the fiber sheet runs parallel to the multi-stage and the both wall surfaces are juxtaposed. A horizontal heat treatment furnace comprising a sealing chamber having a second outlet for the fiber sheet having a multi-stage slit shape in the vertical direction on the outer wall surface,
The heat treatment chamber includes a hot air circulation facility having a hot air introduction portion for blowing hot air substantially parallel to the traveling direction of the fiber sheet, and a hot air discharge portion for discharging the hot air,
Each seal chamber is formed with at least one exhaust port,
Said seal chamber exhaust port of the seal chamber of the exhaust port of the hot air inlet side and the hot air discharge portion side, Ri na have independent exhaust mechanism and exhaust adjusting mechanism,
The pressure in the seal chamber on the hot air introduction portion side where hot air is blown is lower than the pressure on the hot air introduction portion side in the heat treatment chamber, and the pressure in the seal chamber on the hot air discharge portion side that discharges hot air is the pressure on the hot air discharge portion side in the heat treatment chamber. A horizontal heat treatment furnace that is higher and pressure-adjusted . The horizontal heat treatment furnace according to claim 1 , wherein the seal chamber is partitioned vertically by at least one partition plate, and at least one exhaust port is formed in each partitioned seal chamber . The horizontal heat treatment furnace according to claim 1 or 2, wherein the seal chamber is partitioned vertically by a partition plate for each stage of the fiber sheet, and at least one exhaust port is formed in each seal chamber . The horizontal heat treatment furnace according to any one of claims 1 to 3, wherein the heat treatment chamber is partitioned by a partition plate for each stage on which the fiber sheet travels . A heat treatment method for heat-treating a precursor, which is a raw material of carbon fiber, using the horizontal heat treatment furnace according to any one of claims 1 to 4,
  The pressure in the seal chamber on the hot air introduction portion side for blowing hot air is 0.3-5 Pa lower than the pressure on the hot air introduction portion side in the heat treatment chamber, and the pressure in the seal chamber on the hot air discharge portion side for discharging the hot air is hot air in the heat treatment chamber. A heat treatment method that is 0.3 to 5 Pa higher than the pressure on the discharge side.

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