JPH04214186A - Sealing method of in-furnace thermal medium particles in fluidized bed and flame resistant device using the method - Google Patents

Abstract

PURPOSE:To provide a sealing method and its device which are capable of effectively sealing the leakage of heat medium particles from an inlet 23 and an outlet 24 of front drive fiber in a flame resistant device 10 which serves as a fluidized bed. CONSTITUTION:In a flame resistant device 10 which comprises a main body 11 which holds heating medium particles inside, an intake hole 23 and an outlet hole 24 of front drive fiber bored on the aforesaid main body, an air supply system and an air emission system of heating gas which is connected with the main body 11, an attempt is made to install at least two suction holes 29 which are designed to absorbcatch heating medium particles in a holdup chamber 27 and the inlet 25 and outlet 26 of the front drive body fiber 3 or the particles which leaked out in the holdup chamber by way of a porous plate 34 having a finer ventilation hole than the size of the fine particles, near the intake hole 23 and sealing section 12 and 13 which comprises an air suction means 33 connected with the suction hole 29. The leakage of in-furnace heating medium particles 1 from the inlet and outlet holes 23 and 24 can be effectively sealed by means of a bridge 38 formed in the holdup chamber 27.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides a method for effectively sealing in-furnace heat transfer medium particles at the entrance and exit portion of a fluidized bed furnace when a linear workpiece is continuously introduced into and taken out of the fluidized bed furnace. The present invention also relates to a flame-resistant device using the sealing method.

0002

2. Description of the Related Art Conventionally, many heat treatment methods using a fluidized bed furnace using solid particles as a heating medium have been known for continuously heat treating a linear workpiece.

For example, polyacrylonitrile (PAN)
First, a flame-retardant process is performed in which a precursor fiber bundle made of a polymer such as cellulose-based fiber or recycled cellulose-based fiber is heat-treated in an air or oxidizing gas atmosphere at 200 to 300°C.
A method for flame-proofing a precursor fiber bundle, in which carbon fibers with even higher elastic modulus and strength are obtained by carbonization in an inert gas atmosphere such as nitrogen or argon at a temperature of 00 to 2000°C, uses carbon as heat transfer particles. Particles, metal particles, etc. are used, and this is a preferred application example of a heat treatment method using a fluidized bed furnace.

By the way, in the above flame-retardant method, in order to obtain flame-retardant fibers by applying uniform heat treatment to the material to be treated in the furnace, the prerequisites for this are the fluidization state and the temperature in the furnace. It is necessary to make it uniform at all locations.

[0005] As a specific means for this purpose, it is necessary to prevent the heating medium particles inside the furnace from leaking out of the furnace, that is, to reliably seal the heating medium particles inside the furnace at the entrance and exit of the precursor fiber of the fluidized bed furnace. It becomes an essential technology.

The present applicant proposed a sealing method shown in FIG. 3 in Japanese Patent Application Laid-Open No. 1-192825 as a method for sealing heat medium particles in the furnace of such a fluidized bed furnace.

In this sealing method, an inlet 5 for the precursor fibers and a supply of pressurized air are connected to the introduction holes 4 for the precursor fibers 3 of the fluidized bed furnace 2 in which a fluidized bed is formed by the heating medium particles 1 inside. Mouth 6
By providing a cylindrical pressurized seal chamber 7 having The purpose is to prevent leakage of the internal atmosphere and the heating medium particles 1, and some use a similar sealing method for the outlet holes of the precursor fibers.

[0008]

[Problems to be Solved by the Invention] However, although the conventional sealing method described above has the advantage that it does not cause damage to the precursor fibers such as yarn breakage or fluffing because the sealing gas is a gas, There was a problem. That is, (1) Since the sealing pressure in the pressurized sealing chamber 7 is set higher than the furnace internal pressure, sealing gas inevitably flows into the fluidized bed through the precursor fiber introduction and outlet holes. This inflow phenomenon causes a non-uniform fluidization state and temperature distribution of the fluidized bed in the furnace, and there is a problem in that it prevents uniform fluidization of heat transfer particles.

(2) The inlet and outlet holes for the precursor fibers should have as large an opening area as possible, since the fibers are likely to come into contact with these inlet and outlet holes and be damaged when the fibers are introduced into and out of the fluidized bed furnace. Something is desirable.

However, if the opening area of the inlet hole and the outlet hole is increased too much, the heat transfer particles will leak out of the furnace, and in reality, the flow state in the furnace and the uniformity of the temperature in the furnace will be affected. It is very difficult to adjust the balance between the aperture area and the pressurized sealing pressure, and there is a problem in particular when the heat medium has a large bulk density.

[0011] Unless the above-mentioned problems are solved, it will not be possible to uniformly heat treat the material to be fed to the fluidized bed furnace, making it impossible to obtain flame-resistant fibers of excellent quality.

The present invention solves the above-mentioned problems and provides a method for sealing heating medium particles in a furnace, which can effectively seal leakage of heating medium particles from an inlet and an inlet of a workpiece in a fluidized bed furnace, and a method for sealing heat medium particles in a furnace. The purpose of the present invention is to provide a flame-resistant device using a sealing method.

[0013]

[Means for Solving the Problems] In order to achieve the above object, a method for sealing heating medium particles in a fluidized bed furnace according to the present invention includes a method for sealing heat medium particles in a fluidized bed furnace, in which a linear workpiece is fluidized with heated gas. A furnace of a fluidized bed furnace that seals the heat transfer medium particles flowing out of the furnace from the introduction hole and the outlet hole when the heating medium particles are introduced through the introduction hole of the fluidized bed furnace and are led out from the outlet hole after heat treatment. In the method for sealing internal heating medium particles, a retention chamber for retaining the heating medium particles in the fluidized bed furnace is formed in the vicinity of the introduction hole and the outlet hole, and the heating medium particles flowing into the retention chamber are collected in the retention chamber. at least 2 times through the object to be processed.
A bridge of heating medium particles is formed around the object to be processed by suctioning and trapping the heating medium particles through a perforated plate having ventilation holes smaller than the diameter of the heating medium particles through suction holes provided at certain locations. It is characterized by being sealed.

Here, the linear object to be treated includes, for example, linear objects such as filaments, spun yarns, strands, etc., and continuous or discontinuous objects such as tows, woven fabrics, non-woven fabrics, etc. Its cross-sectional shape is not particularly limited. Examples of the linear object to be treated include precursor fiber bundles made of polymers such as polyacrylonitrile (PAN) fibers and recycled cellulose fibers.

[0015] Heat transfer particles refer to solid particles that are fluidized by heated gas, and are composed, for example, of carbon, alumina, silicon carbide, zirconia, silica, etc., singly or in combination as main components. Examples include inorganic particles such as ceramics and glass. In addition, the particle size of is 0.1 to 0
．． Preferably, the thickness is within the range of 5 mm, and the density is 0.
It is preferably within the range of 6 to 2.0 g/cm3.

[0016] A fluidized bed furnace is a fluidized bed furnace in which the heat medium particles in the fluidized bed furnace are fluidized by supplying a heated inert gas such as argon or nitrogen to the heat medium particles. Known devices for heat-treating fibers include, for example, the above-described flameproofing device for precursor fibers, fluidized bed firing furnaces, fluidized bed incinerators, wire heat treatment furnaces, and the like.

The suction speed of the suction means depends on the diameter of the heat medium particles and the depth of the fluidized bed, but the suction speed of the suction means depends on the diameter of the heat medium particles and the depth of the fluidized bed.
It is preferable to set the suction speed within the range of 1.5 to 2.0 Ncm/S per cm.

[0018] Furthermore, in order to achieve the above object, the flameproofing device according to the present invention includes a main body containing heating medium particles therein;
an introduction hole and an outlet hole for the object to be treated, which are formed in the main body;
In a flame-retardant device that includes an air supply system and an exhaust system for the heated gas connected to the main body, and heat-treats the object by fluidizing the heating medium particles with the heated gas, (a) the above-mentioned a retention chamber for heating medium particles provided adjacent to the inlet hole and outlet hole of the main body; (b) an inlet and an outlet for the to-be-processed material opened to the retention chamber; and (c) an inlet to the retention chamber. (d) suction holes provided in at least two locations separated from each other and for suctioning and trapping heat medium particles flowing into the retention chamber through a perforated plate having ventilation holes smaller than the diameter of the heat medium particles; The invention is characterized in that it is provided with an air intake means connected to the air intake means, and a sealing portion consisting of.

Here, the flame-retardant device used in the sealing method of the present invention refers to a known device, such as a precursor made of an organic polymer such as polyacrylonitrile fiber, recycled cellulose fiber, phenol fiber, pitch fiber, etc. The body fibers are flame-resistant treated in a fluidized bed heated to about 200 to 300°C by supplying air or other oxidizing heated gas to a bed of heating medium particles such as carbon, alumina, silicon carbide, and zirconia. means a device that

[0020] The retention chamber may be a cylindrical body having a constant length in the traveling direction of the object to be treated, and may have any shape such as a round cylinder or a rectangular cylinder. Inside this retention chamber,
As will be described later, by suctioning and trapping the heating medium particles flowing into the retention chamber by the suction means, a bridge of heating medium particles with a high agglomeration density is formed around the perforated plate so as to surround the object to be treated. This bridge formed by the heating medium particles greatly affects the atmosphere in the furnace and the sealing performance of the heating medium particles. The force for forming a bridge on a perforated plate is determined by the amount of heat medium sucked and captured near the perforated plate, that is, the product of the cross-sectional area S of the suction hole and the distance H from the suction hole to the workpiece, and the amount of heat transfer at the suction hole. It is determined by the suction power. The sealing performance of the heating medium particles by this bridge depends on the heating medium particle diameter and the height of the fluidized bed, but it also depends on the number of suction holes and the length from the main body's introduction hole or outlet hole to the suction hole in the retention chamber. (hereinafter referred to as seal length) L
, the distance H from the suction hole to the object to be processed, the suction capacity of the suction means, etc. The sealing effect by the bridge is that the seal length L is long and the distance H is small, and the higher the suction force is, the more heat transfer particles are attracted and captured on the perforated plate, so the fracture strength of the bridge itself is stronger, and the sealing effect is the most effective. is large. However, if the seal length L is too long,
The running resistance when the object to be processed passes increases, and the object to be processed also suffers damage due to scratches. On the other hand, the seal length L
If is too short, the amount of heat transfer particles sucked and captured will be insufficient and the sealing effect will not be sufficient.

[0021] It is preferable that the distance H from the suction hole to the object to be treated is kept to the minimum necessary. This is because when the distance H is increased, the suction speed to capture the heat medium particles must also be set high, but by increasing the suction speed, a large amount of fluidizing gas in the fluidized bed also flows out. On the other hand, if the distance H is too short, the object to be processed will come into contact with the inside of the retention chamber,
This is not good because the object to be processed will be damaged.

From this point of view, the seal length L is preferably 50 to 100 mm. When the temperature is within this range, damage caused by abrasion of the object to be treated and outflow of gas and heat transfer particles in the retention chamber to the outside of the furnace can be suppressed as much as possible, and the pressure drop in the retention chamber will not become high.

[0023] The perforated plate is a plate-like body having a plurality of ventilation holes in order to separate the heating medium particles from the gas in the retention chamber at the entrance of the intake hole. Can be used. The inner diameter of the ventilation hole needs to be smaller than the diameter of the heating medium particles in order to capture the heating medium particles, but if it is too small, the heating medium particles will clog on the perforated plate, which will actually worsen the suction trapping effect. do. Therefore,
The inner diameter of the vent hole is preferably within the range of 40 to 80%, more preferably within the range of 50 to 70%, of the heat medium particle diameter.

[0024] The suction holes are provided at two locations in the retention chamber so that the open surfaces thereof face each other with the object to be treated at the center, but it is of course more preferable if they are equally distributed at three or more locations. As the suction means, for example, known suction means such as a vacuum pump, an exhaust blower, an exhaust fan, etc. can be used.

[0025] Line-shaped objects that can be processed by the apparatus according to the present invention include those obtained by spinning organic polymers typified by PAN-based, recycled cellulose-based, phenol-based, and pitch-based fibers. filament, strand, tow, etc.

[0026]

[Operation] The atmosphere inside the retention chamber is sucked by the suction means through the perforated plate from the air supply hole in the retention chamber provided opposite to the workpiece in the fluidized bed furnace filled with heating medium particles. Then, the heating medium particles flowing out into the retention chamber from the inlet and outlet holes of the fluidized bed furnace are captured by the sucked atmosphere and move toward the perforated plate.

The heat medium particles moving toward the perforated plate are blocked from moving because the ventilation holes in the perforated plate are smaller than the heat medium particles, and eventually the agglomeration density increases between the perforated plate and the object to be processed around the perforated plate. Form a high bridge. As this bridge gradually grows and becomes larger, it begins to surround the workpiece and eventually completely seals the workpiece, preventing heat transfer particles from leaking out of the furnace.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the flameproofing device according to the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a schematic vertical sectional view of a flameproofing device according to the present invention. In the figure, 10 is the main body part 1
1, an inlet seal part 12, and an outlet seal part 13. The main body part 11 is a box-shaped container for heat-treating continuously supplied precursor fibers 3 in a fluidized bed of heating medium particles 1 loaded therein. An introduction hole 23 and an outlet hole 24 are opened. Further, 14 is a dispersion plate for supporting the heat medium particles 1. Reference numeral 15 at the bottom is an air supply pipe for supplying heated gas to the fluidized bed, and on the upstream side there is an air supply system for heating gas consisting of an air supply line 16, a heater 17, a flow rate adjustment valve 18, and an air supply blower 19. is connected.

On the other hand, an exhaust system consisting of an exhaust pipe 20 and an exhaust line 21 is connected to the upper part of the main body for exhausting the heated gas that has finished fluidizing the medium particle layer. Note that 22 is a return port for returning heat transfer particles that have slightly leaked out of the furnace from the inlet seal portion 12 and the outlet seal portion 13 into the main body.

[0031] Inlet seal section 12 and outlet seal section 13
Both are for preventing the atmosphere inside the furnace and heat transfer particles from flowing out of the furnace through the introduction and outlet holes 23 and 24 of the main body, and have a substantially symmetrical configuration.

The inlet seal portion 12 has a cylindrical retention chamber 27 with an inner diameter of 20 mm having an inlet 25 for the precursor fibers 3 and an outlet 26, and the introduction hole 23 of the main body and the outlet 26 of the retention chamber are opposed to each other. It is fixed with a flange 28 as shown in FIG.

The retention chamber 27 has a seal length L of 50 mm.
Two suction holes 29 are opened vertically at positions opposite to each other through the precursor fibers 3. An intake pipe 30 is connected to each suction hole 29, and an intake means consisting of an intake line 31, a flow rate control valve 32, and an intake blower 33 is connected. Further, a porous plate 34 made of sintered wire mesh is fixed to each of the suction holes 29 so that its inner surface coincides with the inner circumferential surface of the retention chamber 27 . Note that 35 is a hopper that receives the heat medium particles that have fallen off from the bridge 38 formed in the retention chamber 27, and the return line 36, exhaust blower 37, and heat medium return port 22 constitute a return system for the heat medium particles. are doing.

The above is the configuration of the inlet seal portion 12.
The outlet seal portion 13 also has a similar configuration, so a description thereof will be omitted.

Using the embodiment apparatus constructed as described above, the method for sealing heat medium particles in a furnace according to the present invention was carried out as follows.

First, particles with a diameter of 0.35 mm are placed in the main body 11.
, heat medium particles made of graphite were loaded so that the depth when standing still was 400 mm. And air supply blower 19, heater 1
7 and supply 3Ncm of 280℃ air gas from the air supply hole.
A fluidized bed of heat transfer particles was formed by supplying at a supply rate of /S.

On the other hand, the intake blower 33 was operated by adjusting the flow rate control valve 32 so that the suction speed at the suction hole 29 was 8 Ncm/S and the static pressure was 350 mmH2o. After setting such operating conditions, when precursor fibers 3 made of polyacrylonitrile were continuously fed from the inlet 12 at a yarn speed of 5 m/min, the amount of heat medium particles returned from the hopper 35 to the main body 11 was , 30 g/min/line, it was found that the furnace atmosphere and heat transfer particles were almost completely sealed.

Incidentally, when the supply of the precursor fiber 3 is stopped,
Visual observation of the formation of the bridge 38 around the perforated plate 34 from the inlet 25 revealed that the heating medium particles 1 aggregated as if surrounding the precursor fibers 3, sealing the heating medium particles in the furnace. was confirmed. Example 2 Figure 2 shows Example 1
FIG. 2 is a schematic longitudinal cross-sectional view showing an embodiment of the flameproofing device in which the leakage of heat transfer particles is prevented and the temperature inside the furnace is further improved.

The difference between the device of this embodiment and the device of Embodiment 1 is that air supply systems 39 and 40 for forcing hot air into the retention chamber 27 are provided, and other points are different from the device of Embodiment 1. The configuration is exactly the same as that of the device.

That is, in the device of this embodiment, the precursor fibers 3 are interposed between the outlet 26 of the seal portion 12 and the intake pipe 30 and between the inlet 25 of the seal portion 13 and the intake pipe 30 in FIG. Two air supply pipes 42 are provided so that the air supply holes 41 face each other, and a heater 43, a damper 44, and an air supply blower 45 are connected to these pipes so that hot air having a temperature similar to the temperature inside the furnace can be forced into the pipes. 46. In this case, the amount of hot air forced into the retention chamber 27 from the air supply pipe 42 is such that the forced hot air is transferred between the introduction hole 23 of the main body 11 and the outlet hole 27.
In order to prevent water from flowing into the furnace, check the pressure gauges (not shown) installed in the main body 11 and the retention chamber 27 so that the pressure in the retention chamber is approximately 5 to 30 mmH2 o lower than the pressure in the furnace. It is adjusted by a damper 44. In this case, making the pressure in the retention chamber higher than the pressure in the furnace means that the outside air flowing into the furnace from the retention chamber has an imbalance in the fluidization state and temperature distribution of the fluidized bed in the furnace, as described in the prior art section. This is not preferable because it causes uniformity.

With this configuration, the atmosphere inside the retention chamber 27 is transferred to the intake pipe 3 by the intake blower 33 through the perforated plate 34.
While forming a bridge 38 that seals the precursor fibers 3 in the retention chamber by suctioning from 0, the hot air pushed in from the air supply pipe 42 flows through the inlet hole 23 and the outlet hole 24 to the heating medium particles 1 in the furnace. and prevent the accompanying leakage of the furnace atmosphere. Therefore, the introduction hole 23 and the outlet hole 24
The nearby furnace temperature is maintained uniformly without fluctuation. Furthermore, the hot air pushed into the retention chamber also contributes to reducing the amount of hot air leaking from the introduction hole 23 and the outlet hole 24 to the seal parts 12, 13, so that the amount of exhaust air for forming the bridge 38 can be reduced. This has the effect that energy saving can be achieved and the exhaust capacity of the intake blower 33 can be reduced. In this example, the hot air pushed into the retention chamber 27 was preheated by the heater 43, but this is because when outside air, which is lower than the temperature inside the furnace, is pushed into the retention chamber at the same temperature, the inside of the retention chamber is cooled, and the precursor fibers 3 In order to prevent this, the temperature distribution inside the furnace is changed by flowing low temperature outside air into the furnace from the return port 22. This is to prevent this from happening. However, it goes without saying that the heater does not need to be provided in the case of objects to be treated where there is no risk of tar adhesion.

[0042]

Advantages of the Invention Since the present invention has the configuration described above, it can achieve the following excellent effects. (1) Since a bridge is formed by the heating medium particles themselves so as to surround the object to be treated in the retention chamber, leakage of the heating medium particles from the fluidized bed furnace to the outside of the furnace is significantly reduced. Therefore, the drop in temperature inside the furnace is suppressed, and the pressure distribution inside the furnace is evened out, allowing uniform and stable heat treatment to be applied to the workpieces fed into the furnace, resulting in products of excellent quality. It will be done. (2) Furthermore, since the sealing performance in the retention chamber can be easily adjusted by adjusting the suction amount of the suction means, it is very easy to adjust the balance between the furnace pressure and the furnace temperature. (3) Furthermore, since the heating medium particles in the furnace are reliably sealed at the inlet and outlet seals, the amount of heating medium particles returned to the fluidized bed is relatively small, and the heating energy of the heating medium particles is reduced. Energy savings can be achieved through gradual reduction.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical sectional view showing an embodiment of a flameproofing device according to the present invention.

FIG. 2 is a schematic longitudinal cross-sectional view of a flameproofing device according to the present invention, which is a different embodiment from FIG. 1;

FIG. 3 is a schematic vertical cross-sectional view of an outlet seal portion of a fluidized bed furnace using a conventional sealing method.

[Explanation of symbols]

1...Heating medium particles 2...Fluidized bed furnace 3...Precursor fiber (material to be treated) 6...Air supply port 7...Pressure seal chamber 10...Flame resistant device 12...Inlet seal part 13...Exit seal part 15, 42...Air supply pipe 17, 43...Heater 18, 44...damper 19, 45...Air supply blower 20...exhaust pipe 22... Heat medium return port 4, 23...Introduction hole 24... Outlet hole 5, 25... Entrance 26...exit 27... Retention room 29...Suction hole 30...Intake pipe 33...Intake blower (intake means) 34...Perforated plate 35...hopper 38...Bridge 39, 40...Air supply system 41...Air supply hole 42...Air supply pipe 46...Piping

Claims (2)

[Claims] [Claim 1] When a linear workpiece is introduced through an introduction hole of a fluidized bed furnace in which heating medium particles are fluidized with heated gas, and then taken out from an outlet hole after being heat-treated, In the method for sealing heating medium particles in a fluidized bed furnace that seals the heating medium particles flowing out of the furnace from the outlet hole, the heating medium particles in the fluidized bed furnace are retained in the vicinity of the introduction hole and the outlet hole. forming a retention chamber in which the heating medium particles flow out into the retention chamber, through suction holes provided in at least two locations in the retention chamber through the object to be treated, and venting holes smaller than the diameter of the heating medium particles; A method for sealing heating medium particles in a fluidized bed furnace, characterized by forming a bridge of heating medium particles around the object to be processed and sealing the object by suctioning and trapping the particles with a suction means through a perforated plate having a porous plate. . 2. A main body having heating medium particles therein, an inlet hole and an outlet hole for the object to be processed, which are opened in the main body, and an air supply system and an exhaust system for the heated gas connected to the main body. In a flame-retardant device that heat-treats the object to be treated by fluidizing the heating medium particles with heated gas, the flame-retardant device comprises: a retention chamber for heat transfer particles; (b) an inlet and an outlet for the to-be-processed material opened to the retention chamber; and (c) at least two spaces provided in the retention chamber and separated from each other, the flow of which flows into the retention chamber. A sealing portion is provided, which includes a suction hole that suctions and captures the heat medium particles through a perforated plate having ventilation holes smaller than the diameter of the heat medium particles, and (d) an air suction means connected to the suction hole. A flame-retardant device featuring: