JP2003269866A - Induction heating dry distillation furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a lowering of strength of a furnace body in high temperatures. <P>SOLUTION: The furnace body 1 of this dry distillation furnace for induction heating by a heating coil 2 is formed in double structure comprising an inner furnace made of a nonmagnetic material, and an outer furnace 10 made of a magnetic material. The inner furnace 9 is structurally held by the outer furnace 10 through spacers 12, 13. The inner furnace 9 functions as a heating body, and the outer furnace 10 functions as a structural member for holding the inner furnace 9. As a result, the inner furnace 9 is prevented from crack initiation, distortion, or the like regardless of a lowering of mechanical strength caused by a high temperature, and in the outer furnace 10, an induction current is minimized to reduce heat loss. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating type dry distillation furnace which heats a furnace body by induction heating to dry-treat an object to be treated such as plastic waste in the furnace, and more particularly to the structure of the furnace body. .

[0002]

2. Description of the Related Art FIG. 13 is a vertical sectional view showing a schematic structure of a conventional batch type dry distillation furnace. In FIG. 13, the carbonization furnace is configured by arranging a heating coil 2 on the outside of a hollow cylindrical furnace body 1 composed of a vertically standing cylindrical body with a bottom. The upper surface of the furnace body 1 is closed by a disk-shaped furnace lid 3. The furnace body 1 is suspended and supported by an annular support plate 5 which is supported by columns 4 at several points, via a flange portion integrally formed on the upper portion. When an electric current is passed through the heating coil 2 from a high frequency power source (not shown), the generated magnetic flux interlinks with the furnace body 1, and an induced current mainly flows in the side wall of the furnace body 1 facing the heating coil 2. The furnace body 1 generates heat due to the resistance loss due to this induced current, and the object to be treated (not shown), such as plastic waste, charged in the furnace is carbonized by radiant heat from the furnace wall.

FIG. 14 is a vertical sectional view showing a schematic structure of the continuous type dry distillation furnace (rotary kiln). In FIG. 14, the carbonization furnace is configured by arranging a heating coil 2 on the outside of a hollow cylindrical furnace body 1 composed of a horizontally placed cylindrical body. The furnace body 1 is rotatably supported by support rollers 6 at both ends, and is rotationally driven by a motor-driven driving roller 7. From the right end of FIG. 14, the not-shown object to be fed through the object supply pipe 8 is sent toward the left end as the furnace body 1 rotates, during which the heating coil 2 is energized to generate heat in the furnace body 1. Is carbonized.

[0004]

In such a carbonization furnace, the furnace body 1 is made of a magnetic metal, generally an iron material in order to generate heat by induction heating. For example, if the carbonization temperature is about 550 ° C., 700 ° C. Heated to a degree. However, the mechanical strength (tensile strength and yield point) of iron material sharply decreases at high temperatures, and at 700 ° C, it is ⅓ of normal temperature.
It falls to ~ 1/4. Therefore, in the above-mentioned carbonization furnace, the furnace body 1 is likely to be deformed, distorted, cracked, and the like, and particularly in the portion near the end of the heating coil 2, since the temperature gradient is large, stress is concentrated and there is a large risk of causing defects. .

Therefore, an object of the present invention is to improve the safety of the induction heating type dry distillation furnace by devising the structure of the furnace body.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is an induction heating method in which a hollow cylindrical furnace body is induction-heated by a heating coil arranged outside the furnace body, and an object to be treated in the furnace is carbonized. In the heating type dry distillation furnace, the furnace body has a double structure composed of an inner furnace made of a magnetic material and an outer furnace made of a non-magnetic material, and mainly the inner furnace is induction-heated, and the inner furnace is operated by the outer furnace. It is to be structurally retained (Claim 1).

According to the first aspect of the present invention, the heat-generating inner furnace does not have a function as a structural material as much as possible, and the furnace body provided outside functions as a structural material while suppressing heat generation as much as possible. For that purpose, the inner furnace is made of a magnetic material and the outer furnace is made of a non-magnetic material. Thus, by appropriately setting the wall thickness of each furnace body, most of the magnetic flux from the heating coil passes through the outer furnace and is linked to the inner furnace, so that the inner furnace is mainly heated. The wall thickness of the furnace body is determined from the magnetic flux penetration depth λ defined by the following equation.

Λ = (2 × ρ / ωμ) ^1/2 (mm) (where ρ is the resistivity of the material, ω is the angular frequency of the power source, and μ is the magnetic permeability).

In claim 1, the magnetic material may be an iron material, and the non-magnetic material may be a stainless material (claim 2).

In the second aspect, a gap may be provided between the inner furnace and the outer furnace, and a spacer of an insulator may be inserted into this gap (claim 3). By providing a gap between the inner and outer furnace bodies, heat transfer from the inner furnace to the outer furnace can be reduced, thermal strain of the outer furnace can be suppressed, and heat escape from the outer furnace can be reduced. In that case, a spacer of an insulating material is inserted in the gap between the furnace bodies, and the inner furnace is structurally held by the outer furnace through the spacer.

In Claim 3, it is preferable that the gap is filled with a heat insulating material (Claim 4). This results in less heat transfer from the inner furnace to the outer furnace. Further, claim 3
In, the gap can be evacuated, so that the heat conduction in the gap can be made almost zero (claim 5).

In the first aspect, a slit may be provided in a furnace wall of the outer furnace facing the heating coil in a direction orthogonal to the winding of the heating coil (claim 6). Thereby, the induced current that tends to flow in the outer furnace in the circumferential direction can be blocked by the slit, and the heat generation of the outer furnace can be suppressed.

In claim 5, a slit is provided in a furnace wall of the outer furnace facing the heating coil in a direction orthogonal to a winding of the heating coil, and the slit is provided inside or outside the outer furnace. It is preferable to provide an auxiliary furnace made of an insulating material or a non-magnetic material that closes (claim 7).
With this, even if a slit is provided in the outer furnace, the above-described vacuum evacuation is possible, and it is possible to simultaneously suppress heat generation in the outer furnace by the slit and suppress heat conduction by evacuation.

In the first aspect of the present invention, the outer furnace can be constructed by arranging a plurality of support members that are long in the axial direction with a gap in the circumferential direction (claim 8). As a result, the induced current that tends to flow to the outer furnace is blocked by the gap between the support members,
The heat generation of the outer furnace can be suppressed.

In claim 2, it is preferable that the inner furnace is detachably installed, which facilitates maintenance and inspection of the inner furnace (claim 9).

In the second aspect of the present invention, it is preferable that the outer furnace, which is a cylindrical body with a bottom, insulates between a bottom wall and a side wall. Thereby, the induced current generated in the outer furnace can be divided between the bottom wall and the side wall to suppress heat generation.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention.
FIG. 3 is a vertical cross-sectional view of the batch type dry distillation furnace. In FIG. 1, the carbonization furnace is configured by arranging a heating coil 2 on the outside of a hollow cylindrical furnace body 1 composed of a vertically standing cylindrical body with a bottom. The upper surface of the furnace body 1 is closed by a disk-shaped furnace lid 3. The furnace body 1 is suspended and supported by an annular support plate 5 which is supported by columns 4 at several points, via a flange portion integrally formed on the upper portion. These structures are shown in FIG.
This is substantially the same as the conventional example. Here, the furnace body 1 has a double structure including an inner furnace 9 made of a magnetic material (for example, iron) and an outer furnace (hereinafter, referred to as “outer furnace”) 10 made of a non-magnetic material (for example, stainless steel). The inner furnace 9 is structurally held by the outer furnace 10.

The inner furnace 9 and the outer furnace 10 are separated by a gap 11, and the gap 11 is made of an insulator having a small thermal conductivity.
For example, annular spacers 12 and 13 made of heat-resistant brick
Has been inserted. The spacers 12 are fixed to the inside of the side wall of the outer furnace 10 at, for example, two upper and lower locations by, for example, bolts (not shown). The spacer 13 is placed on the bottom wall of the outer furnace 10 and is fixed by, for example, a bolt (not shown). Care is taken that the bolt does not come into contact with the inner furnace 9. The inner furnace 9 is removably inserted into the outer furnace 10, is supported by the bottom wall of the outer furnace 10 via a spacer 13, and is constrained by the side wall of the outer furnace 10 via a spacer 12. The upper end surface of the inner furnace 9 is separated from the lower surface of the furnace lid 3 via a gap 14.

When an electric current is passed through the heating coil 2 from a high frequency power source (not shown), the generated magnetic flux links with the furnace body 1.
The above-mentioned magnetic flux penetration depth λ of stainless steel and iron is about 70 mm and 4 mm, respectively, when the current frequency is 50 Hz. Therefore, the wall thickness of the outer furnace 10 made of stainless steel is set to about 10 mm, which is sufficiently smaller than the magnetic flux penetration depth λ, and the inner furnace 9 made of iron is
If the thickness of the furnace wall is about 10 mm, which is sufficiently larger than the magnetic flux penetration depth λ, most of the magnetic flux from the heating coil 2 is outside the furnace 10.
And the inner furnace 9 is linked to the inner furnace 9, and the induced current mainly flows in the inner furnace 9. As a result, the inner furnace 9 generates heat, but the outer furnace 10 hardly generates heat.

In this case, the mechanical strength of the iron material forming the inner furnace 9 decreases due to the high temperature, but the inner furnace 9 is
Since it is surrounded and held by, the function as a structural material is not often required, and the generated stress is small. On the other hand, since the outer furnace 10 generates less heat, the mechanical strength is less deteriorated, and the inner furnace 9 is safely held as a structural material, while the heat radiated to the outside is less.

In FIG. 1, the spacer 12 in the gap 11,
Insulation materials such as glass wool, except for 13
It can be filled, which makes it possible to improve heat insulation. In the illustrated first embodiment, the spacer 1
Although the example in which 2 and 13 are partially provided is shown, it is also possible to insert a spacer into the entire gap 11, and thereby the holding force for the inner furnace 9 can be increased. on the other hand,
The inner furnace 9 and the furnace lid 3 are thermally insulated by the gap 14. However, as shown by the chain double-dashed line in FIG. The sex becomes even better. Stainless steel is suitable for the material of the furnace lid 3, but if it is made of an inorganic material such as brick, it becomes more advantageous in terms of both heat insulation and suppression of heat generation due to leakage magnetic flux.

FIG. 2 is a vertical sectional view of a furnace body showing a second embodiment of the present invention. In the second embodiment, a vacuum pump 17 for vacuuming the gap 11 in FIG. 1 is provided, and the gap 11 is a vacuum layer. The spacers 12 and 13 are provided with ventilation holes 18 that connect the front and rear spaces to each other, and a heat insulating material 16 seals between the inner furnace 9 and the furnace lid 3. By operating the vacuum pump 17 and forming the gap 11 into a vacuum layer, the thermal conductivity between them becomes almost zero, and the inner furnace 9
The radiant heat is the only heat transfer from the outside to the outer furnace 10. Further, in that case, if a small hole is formed in the heat insulating material 16 so that the inside of the furnace is communicated with the upper part of the gap 11 and the vacuum pump 17 is constantly operated during the operation of the furnace, the dry distillation gas generated from the object to be treated is simultaneously discharged. Can be discharged. Also in FIG. 2, if the cotton-like heat insulating material having air permeability is filled in the gap 11, the radiant heat can be blocked.

FIG. 3 is a longitudinal sectional view of a furnace body showing a third embodiment of the present invention, and FIG. 4 is a perspective view of the outer furnace in FIG. In the third embodiment, a slit 19 is provided on the furnace wall facing the heating coil 2 of the outer furnace 10 in FIG. The slits 19 are provided in a direction orthogonal to the winding of the heating coil 2, that is, in the axial direction of the outer furnace 10, and are arranged in the circumferential direction of the outer furnace 10 at equal pitches. According to the third embodiment, the circumferential induced current generated in the outer furnace 10 is cut off by the slits 19, and the heat generation of the outer furnace 10 is reduced.

FIG. 5 is a vertical sectional view of a furnace body showing a fourth embodiment of the present invention. The fourth embodiment is the outer furnace 10 according to the second embodiment (FIG. 2) in which the gap 11 is a vacuum layer.
In the case where the slit 19 similar to that shown in FIG.
An auxiliary furnace 20 is provided to close the slit 19. The auxiliary furnace 20 is made of a non-magnetic material, such as stainless steel, as a bottomed cylindrical body that adheres to the inside of the outer furnace 10, and is fitted in the outer furnace 10 in an airtight manner by, for example, shrink fitting. The strength of the auxiliary furnace 20 is only required to withstand atmospheric pressure, and the wall thickness is minimized so that the magnetic flux of the heating coil 2 can pass through. FIG. 6 shows a fifth embodiment in which the auxiliary furnace 20 in FIG. 5 is fitted on the outside of the outer furnace 10. In FIG. 6, the deformation of the auxiliary furnace 20 due to the atmospheric pressure is caused by the outer furnace 10.
Since it is supported by, there is an advantage that the wall thickness of the auxiliary furnace 20 can be made thinner than that in FIG.

FIG. 7 is a longitudinal sectional view of a furnace body showing a sixth embodiment of the present invention, and FIG. 8 is a partial perspective view of an outer furnace thereof. In the sixth embodiment, the outer furnace 10 is configured by arranging a plurality of support members that are long in the axial direction with a gap in the circumferential direction. 7 and 8, in the outer furnace 10, a plurality of support members 23 made of flat rectangular members are circumferentially joined by, for example, welding, over a pair of upper and lower frame members 21 and 23 having an L-shaped cross section. The bottom material 24 is also joined to the lower part by welding. Each of the members 22 to 25 is made of a non-magnetic material such as stainless steel. Even in such a configuration, since the side wall of the outer furnace 10 is divided equivalently to that where the slit 19 (FIG. 4) is provided, generation of an induced current is suppressed and heat loss is reduced.

FIG. 9 is a partial perspective view of an outer furnace showing a seventh embodiment of the present invention. In the seventh embodiment, an insulating material 25 is inserted between the frame body 22 and the furnace bottom material 24 in FIG. It is a thing. Thereby, the side wall of the outer furnace 10 is electrically insulated from the furnace bottom material 24, and the induced current in the outer furnace 10 is further suppressed.

FIG. 10 shows Embodiment 8 of the present invention in a continuous dry distillation furnace. In FIG.
The difference from the conventional example of FIG. 14 is that the hollow cylindrical furnace body 1 made of a horizontally placed cylindrical body has an inner furnace (inner furnace) 9 made of a magnetic material (for example, iron) and a non-magnetic material (for example, The other structure is substantially the same as that of the conventional example in that it has a double structure including an outer furnace (outer furnace) 10 made of stainless steel, and the inner furnace 9 is structurally held by the outer furnace 10. Is. The inner furnace 9 and the outer furnace 10 are separated by a gap 11, and an annular spacer 12 made of an insulating material having a small thermal conductivity, for example, heat-resistant brick is inserted in the gap 11. The spacers 12 are provided, for example, at the three front and rear locations in the outer furnace 10.
Is fixed to the inner side wall of, for example, by a bolt (not shown). The inner furnace 9 is detachably inserted into the outer furnace 10, and the outer periphery of the inner furnace 9 is restrained by the side wall of the outer furnace 10 via the spacer 12.

When a high-frequency current (not shown) is passed through the heating coil 2, the generated magnetic flux links with the furnace body 1. The wall thickness of the outer furnace 10 made of stainless steel is set sufficiently smaller than the magnetic flux penetration depth, the wall thickness of the inner furnace 9 made of iron is set sufficiently larger than the magnetic flux penetration depth, and most of the magnetic flux passes through the outer furnace 10 and the inner furnace 9 This is the same as the batch-type carbonization furnace described above in that the inner furnace 9 generates heat but the outer furnace 10 hardly generates heat, as a result of the induction current flowing mainly through the inner furnace 9. The inner furnace 9 is heated to, for example, about 550 ° C., and an object to be processed (not shown) introduced into the furnace through the supply pipe 8 is
It is carbonized by radiant heat from the furnace wall. Even if the mechanical strength of the inner furnace 9 is lowered due to high temperature, the inner furnace 9 is surrounded and held by the outer furnace 10, and therefore no problem in strength occurs.
On the other hand, since the outer furnace 10 generates less heat, the mechanical strength is less deteriorated, the inner furnace 9 is safely held as a structural material, and less heat is dissipated to the outside.

FIG. 11 is a partial perspective view showing Embodiment 9 in which a slit 19 is provided in the furnace wall facing the heating coil 2 of the outer furnace 10 in FIG. The slit 19 is
The direction orthogonal to the winding of the heating coil 2, that is, the outer furnace 10
Are provided in the axial direction of the outer furnace 10 and are arranged in the circumferential direction of the outer furnace 10 at equal pitches. According to the ninth embodiment, as in the batch type dry distillation furnace, the circumferential induced current generated in the outer furnace 10 is interrupted by the slits 19 to reduce heat generation.

FIG. 12 is a partial perspective view showing an embodiment 10 in which the outer furnace 10 in FIG. 10 is constructed by arranging a plurality of support members which are long in the axial direction with a gap in the circumferential direction. The outer furnace 10 extends over several annular frame bodies 21 in the axial direction,
A plurality of support members 23 made of flat rectangular members are connected in the circumferential direction, for example, by welding. Each member 22 and 24
Is formed of a non-magnetic material such as stainless steel. Even in such a configuration, the outer furnace 10 has a slit 19 on the side wall.
(FIG. 11) is equivalently divided, so that generation of induced current is suppressed and heat generation is reduced.

[0031]

As described above, according to the present invention, the furnace body for induction heating has a double structure consisting of an inner furnace of non-magnetic material and an outer furnace of magnetic material, and the inner furnace functions as a heating element. By making the outer furnace function as a structural material to hold the inner furnace, cracks and strains do not occur in the inner furnace despite the decrease in mechanical strength due to high temperature, and the outer furnace minimizes the induced current. It can be suppressed to reduce heat loss. Therefore, the safety and energy efficiency of the induction heating dry distillation furnace can be improved, and an inexpensive material can be used to reduce the cost.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a batch type dry distillation furnace showing a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of a batch type carbonization furnace showing a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of a main part of a batch type dry distillation furnace showing a third embodiment of the present invention.

4 is a perspective view of the outer furnace in FIG.

FIG. 5 is a longitudinal sectional view of a main part of a batch type dry distillation furnace showing a fourth embodiment of the present invention.

FIG. 6 is a longitudinal sectional view of a main part of a batch type dry distillation furnace showing a fifth embodiment of the present invention.

FIG. 7 is a longitudinal sectional view of a main part of a batch type dry distillation furnace showing a sixth embodiment of the present invention.

FIG. 8 is a partial perspective view of the outer furnace in FIG.

FIG. 9 is a partial perspective view of an outer furnace showing a seventh embodiment of the present invention.

FIG. 10 is a vertical sectional view of a continuous dry distillation furnace showing an eighth embodiment of the present invention.

FIG. 11 is a partial perspective view of an outer furnace of a continuous dry distillation furnace showing a ninth embodiment of the present invention.

FIG. 12 is a partial perspective view of an outer furnace of a continuous dry distillation furnace showing a tenth embodiment of the present invention.

FIG. 13 is a vertical sectional view of a batch type carbonization furnace showing a conventional example.

FIG. 14 is a vertical sectional view of a continuous dry distillation furnace showing a conventional example.

[Explanation of symbols]

1 furnace body 2 heating coils 3 furnace lid 9 Inner furnace 10 Outer furnace 11 Gap 12 spacers 13 Spacer 15 Insulation 16 Insulation 17 Vacuum pump 18 vents 19 slits 20 auxiliary furnace 21 frame 22 frame 23 Support material 24 Furnace bottom material 25 insulation

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4K051 AA00 AA03 AA05 AB03 BA02                       BA04                 4K063 AA01 AA12 BA13 CA01 CA02                       CA05 FA36 FA39

Claims (10)

[Claims] 1. An induction heating type carbonization furnace in which a hollow cylindrical furnace body is induction-heated by a heating coil arranged outside thereof to dry-distill an object to be treated in the furnace, wherein the furnace body is an inner furnace made of a magnetic material. And an outer furnace made of a non-magnetic material, having a double structure, and mainly the inner furnace is induction-heated, and the inner furnace is structurally held by the outer furnace. Carbonization furnace. 2. The induction heating dry distillation furnace according to claim 1, wherein the magnetic material is an iron material and the non-magnetic material is a stainless material. 3. The induction heating dry distillation furnace according to claim 2, wherein a gap is provided between the inner furnace and the outer furnace, and an insulating material spacer is inserted into the gap. 4. The induction heating dry distillation furnace according to claim 3, wherein the gap is filled with a heat insulating material. 5. The induction heating dry distillation furnace according to claim 3, wherein the gap is evacuated. 6. The induction heating dry distillation furnace according to claim 1, wherein the furnace wall of the outer furnace facing the heating coil is provided with a slit in a direction orthogonal to the winding of the heating coil. 7. A furnace wall facing the heating coil of the outer furnace is provided with a slit in a direction orthogonal to the winding of the heating coil, and an insulating material for closing the slit inside or outside the outer furnace. The induction heating dry distillation furnace according to claim 5, further comprising an auxiliary furnace made of a non-magnetic material or a non-magnetic material. 8. The induction heating dry distillation furnace according to claim 1, wherein the outer furnace is configured by arranging a plurality of support members that are long in the axial direction with a gap in the circumferential direction. 9. The induction heating dry distillation furnace according to claim 2, wherein the inner furnace is detachably installed. 10. The induction heating dry distillation furnace according to claim 2, wherein an insulation is provided between a bottom wall and a side wall of the inner furnace having a bottomed cylinder.