JPH08170879A - Vertical type muffle furnace - Google Patents

Abstract

PURPOSE: To obtain a vertical type muffle furnace which enables the restricting of the deformation of a muffle less near a bottom part of a furnace body by erecting a heat insulating wall on the bottom part of the furnace covering the surface a side wall part of the muffle with a gap facing an exhaust port provided on a side wall of the furnace near the bottom part of the furnace body. CONSTITUTION: A heat insulating wall 20 erected on the top surface 13a of a furnace bottom part 13 presents a shape of a short cylinder with the inner diameter thereof almost the same as the diameter of a muffle through hole 17 and covers the circumference of the surface of a side wall part 3a of a muffle 3 through a gap 21. With the height H thereof made larger than the height (h) of an exhaust port 15, the heat insulating wall 20 covers exhaust port opposing parts 3b and 3b facing exhaust ports 15 and 15 in the side wall part 3a of the muffle 3 and the surfaces of partially circumferential surface shaped non-opposed parts 3c and 3c with the height H therebetween. In the heat insulating wall 20, a heat insulating material 23 comprising a ceramic wool sheet is laminated on the side of the inner circumferential surface of a short cylindrical mounting ring 22 made up of a divided fireproof steel plate and the heat insulating wall 20 is mounted securely with a pin 24 fastened on the mounting ring 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical muffle furnace for continuously heat treating strip material.

[0002]

2. Description of the Related Art As a vertical muffle furnace of this type, generally, a cylindrical muffle in which an upward traveling strip penetrates is hung so as to penetrate a cylindrical furnace body, and a muffle between the furnace body and the muffle is suspended. Burning is performed in the combustion chamber by a burner, and heat treatment such as bright annealing of the strip is performed in a reducing or non-oxidizing atmosphere gas filled in the muffle, and the combustion gas after the muffle heating is burned by an exhaust fan. A furnace configured to suck and discharge to the outside is used.

On the side wall of the furnace near the bottom of the furnace,
The exhaust port for exhausting the combustion exhaust gas is bored, and there is a large difference in the thermal radiation heating amount with respect to the muffle between the exhaust port and the inner wall surface of the furnace side wall other than the exhaust port (the muffle from the exhaust port). On the contrary, a large amount of heat is emitted from the muffle to the exhaust port.) Moreover, if the muffle through hole at the bottom of the furnace has insufficient seal, cold air will enter through the gap between the through hole and the muffle. However, the inflow rate becomes large near the exhaust port, and the temperature distribution in the circumferential direction of the side wall of the muffle near the bottom of the furnace becomes non-uniform, and the thermal stress locally becomes excessively large. The deformation is locally large, and the above deformation is accumulated by the repeated heating and cooling of the muffle accompanying the repeated operation of the furnace, which causes cracks in the side wall portion and causes the outflow of the atmospheric gas in the muffle. Etc. destroy the refractory filling strips spout formed, it had a variety of problems.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and it is an object of the present invention to provide a vertical muffle furnace capable of suppressing the deformation of the muffle near the bottom of the furnace body to a small amount. .

[0005]

A vertical muffle furnace according to the present invention is a vertical muffle furnace in which a muffle is hung through a furnace body and an exhaust port provided in a side wall of the furnace body near the bottom of the furnace. A heat insulating wall that faces the muffle and covers the surface of the side wall of the muffle with a clearance is erected on the furnace bottom.

The heat insulating wall in the present invention may be in the form of a short cylindrical wall that covers the entire circumference (one round) of the surface of the side wall of the muffle, or may be a curve that covers a part of the circumference of the surface of the side wall of the muffle. It may be wall-shaped.

[0007]

In the vertical muffle furnace of the present invention, the heat insulating wall erected on the upper surface of the bottom of the furnace covers the side wall surface of the muffle facing the exhaust port to prevent heat radiation from the side wall to the exhaust port. Then, the temperature of the side wall is prevented from lowering, and the temperature distribution in the circumferential direction of the side wall is made uniform.

When the heat insulating wall is formed of a short cylindrical wall which covers the entire circumference of the surface of the side wall of the muffle, radiant heat from the inner wall surface of the furnace side wall to the side wall of the muffle is equal to the height of the heat insulating wall. Of the side wall of the muffle that receives almost no radiant heat because it is cut over the entire circumference and thereby faces the exhaust port, and the other part (non-opposing part) that receives the radiant heat. The difference in the amount of heat received is eliminated, and the temperature distribution in the circumferential direction of the side wall is made more uniform.

When the heat insulating wall is a curved wall body that covers a part of the circumference of the side wall surface of the muffle, the heat insulating wall is
When the sealability of the muffle through hole at the bottom of the furnace is insufficient, the cold airflow flowing from the clearance between the through hole and the muffle flows intensively through the clearance near the exhaust port and flows into the exhaust port. Acts as a baffle or diaphragm to prevent
Since the cold air flow is dispersed in the circumferential direction of the clearance, local cooling of the side wall of the muffle by the cold air flow is prevented, and the temperature distribution in the circumferential direction is further homogenized.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the figure, 1 is a vertical muffle furnace, and a furnace body 2
And a muffle 3 penetrating the furnace body 2, the furnace body 2 is erected on a base 4, and the upper end of the muffle 3 is suspended by a pedestal 5. 6 is a slit-shaped charging port through which the strip 7 passes, 8 is a refractory material filled and fixed inside the muffle 3 to form the charging port 6, and 9 is a seal attached to the lower end surface of the muffle 3. It is a device. Further, 10 is an extraction port, to which a chamber 11 forming a cooling zone is connected.

Reference numeral 12 is a blower for exhausting combustion gas, which is connected via a duct 16 to two exhaust ports 15 and 15 which are formed in the furnace side wall 14 of the furnace body 2 in the vicinity of the furnace bottom portion 13 of the furnace body 2. Has been done. Further, a burner for heating is provided on the furnace side wall 14, but its illustration is omitted. Further, 17 is a muffle through hole provided in the furnace bottom portion 13, and 18 is a through hole sealing device for this muffle through hole seal, which is a ring-shaped ceramic wall material slidably contacting the side wall surface of the exposed portion of the muffle 3. Are laminated and attached to the lower surface of the furnace bottom 13.

On the other hand, reference numeral 20 is a heat insulating wall provided upright on the upper surface 13a of the furnace bottom portion 13, and has a short cylindrical shape whose inner diameter is substantially the same as the hole diameter of the muffle through hole 17, and the side wall portion 3 of the muffle 3 is provided.
There is a clearance 21 (through) on the entire circumference of the surface of a.
Covering. As shown in FIG. 4, the height H of the heat insulating wall 20 is set higher than the height h of the exhaust port 15, and the exhaust port facing portion 3b, which faces the exhaust ports 15, 15 of the side wall portion 3a of the muffle 3, The heat insulating wall 20 covers the surfaces of 3b and the non-opposing portions 3c, 3c (see FIG. 3) in the shape of partial circumferential surfaces having a height H between them.

As shown in FIG. 4, the heat insulating wall 20 in this embodiment is composed of a ceramic wool sheet on the inner peripheral surface side of a short cylindrical mounting ring 22 made of a heat resistant steel plate and divided into an appropriate number. A pin 24 in which a heat insulating material 23 is laminated and fixed to the mounting ring 22.
It is fixedly attached by. And the leg 2 of the mounting ring 22
2a is fixed to the furnace shell 25 of the furnace bottom 13 and the refractory layer 26
The rod 27 penetrating the
It is fixedly mounted on the top.

In the vertical muffle furnace 1 having the above structure,
In the combustion chamber 19 between the furnace body 2 and the muffle 3, the combustion gas generated by the combustion of a burner (not shown) is a side wall portion 3 a of the muffle 3 and a furnace inner wall surface 14 of the furnace side wall 14.
After heating a, it flows out from the exhaust port 15 and is discharged to the outside of the furnace by the blower 12. The muffle 3 is not only directly heated by this combustion gas but also radiatively heated by radiant heat from the furnace inner wall surface 14a. However, since the furnace inner wall surface 14a does not exist at the exhaust port 15, the conventional heat insulating wall 20 is not provided. In the furnace, the exhaust port facing portion 3b of the side wall 3a of the muffle not only receives this radiant heating, but also radiates a large amount of heat toward the exhaust port 15 having a large radiant heat absorbing ability close to a black body. The temperature drop is remarkable with respect to the other side wall portions 3a.

On the other hand, in the furnace of the present invention, since the heat insulating wall 20 covers the exhaust port facing portion 3b of the muffle, the heat radiation to the exhaust port 15 is blocked to prevent the temperature from decreasing. Further, in this embodiment, since the heat insulating wall 20 covers the entire circumferential portion including the non-opposing portion 3c of the side wall portion 3a at a constant height, the radiant heat from the furnace inner wall surface 14a is above the side wall portion of the covering portion. 3a is given almost uniformly on the circumference,
As a result, the temperature distribution in the circumferential direction of the side wall portion 3a of the muffle is made uniform, the local excessive thermal stress portion is eliminated, and the deformation of the side wall portion 3a is reduced.

Next, FIG. 5 shows another embodiment of the present invention.
It has the same configuration as the above-mentioned embodiment except that the two heat insulating walls 30 facing the exhaust port 15 have a curved wall shape that covers a part of the circumference of the surface of the side wall portion 3a of the muffle. Therefore, the same parts as those in FIG.
Detailed description is omitted.

In the vertical muffle furnace 31 of this embodiment, the heat insulating wall 30 covers the exhaust port facing portion 3b of the side wall 3a of the muffle to prevent heat radiation to the exhaust port 15 and prevent a temperature drop. Further, when the sealability of the through-hole sealing device 18 is insufficient, the cold air flowing into the furnace body 2 through the clearance 21 is prevented from flowing intensively to the clearance 21 portion near the exhaust port 15. Since the cold air flow is dispersed in the clearance 21 to prevent the side wall 3a of the muffle from being locally cooled, the temperature distribution in the circumferential direction of the side wall is made uniform and deformation is reduced.

The present invention is not limited to the above embodiment, and the heat insulating walls 20 and 30 may have structures and materials other than the above. In the above embodiment, the seal device for the muffle through hole 17 is the through hole seal device 18 having a ring-shaped seal material that is in sliding contact with the outer peripheral surface of the exposed portion of the muffle 3. Is also applicable to a vertical muffle furnace using a seal device of a type in which a bellows-shaped gas seal material that expands and contracts in the vertical direction is attached between the lower end of the furnace body 2 and the lower end of the muffle 3. Is.

[0019]

As described above, according to the present invention,
The heat insulating wall covering the surface of the side wall of the muffle facing the exhaust port prevents a local temperature decrease of the side wall and reduces the thermal stress due to the temperature decrease. The muffle deformation can be suppressed to a small amount.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a vertical muffle furnace showing an embodiment of the present invention.

FIG. 2 is an enlarged vertical sectional view of a lower portion of the vertical muffle furnace shown in FIG.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is an enlarged vertical sectional view of a B part in FIG.

FIG. 5 is a view corresponding to FIG. 3 showing another embodiment of the present invention.

[Explanation of symbols]

1 ... Vertical muffle furnace, 2 ... Furnace body, 3 ... Muffle, 3a
... Side wall part, 3b ... Exhaust port facing part, 13 ... Furnace bottom part, 13
a ... top surface, 14 ... furnace side wall, 15 ... exhaust port, 17 ... muffle through hole, 20 ... heat insulating wall, 21 ... clearance, 30 ... heat insulating wall, 31 ... vertical muffle furnace.

Claims (3)

[Claims] 1. In a vertical muffle furnace in which a muffle is suspended through a furnace body, heat insulation that covers a side wall surface of the muffle with a gap facing an exhaust port provided in a furnace side wall near the bottom of the furnace body. A vertical muffle furnace characterized in that a wall is erected on the furnace bottom. 2. The vertical muffle furnace according to claim 1, wherein the heat insulating wall comprises a short cylindrical wall body that covers the entire circumference of the side wall surface of the muffle. 3. The vertical muffle furnace according to claim 1, wherein the heat insulating wall comprises a curved wall body that covers a part of the circumference of the surface of the side wall of the muffle.