JP7700656B2 - heating furnace - Google Patents

Description

This invention relates to a heating furnace, and more specifically to a heating furnace characterized by technical means for suppressing thermal deterioration of the sealing member arranged around the opening.

In heating furnaces used in the steel industry, a furnace door may be installed at an opening formed in the furnace body through which the material to be heat treated is brought in and/or taken out to prevent heat radiation. In this case, a sealing material is used around the opening in contact with the furnace door to keep the inside of the furnace airtight, but there is a problem in that the sealing material is easily deteriorated by the heat inside the furnace.

One method for protecting such sealing members from heat is to directly or indirectly cool the sealing members using cooling water (coolant) (see, for example, Patent Document 1 below). However, the method of cooling the sealing members using cooling water has numerous problems, including a drop in the temperature inside the reactor due to leakage from the cooling water piping, failure of equipment around the piping, a decrease in the amount of water due to clogging of the cooling water piping and the resulting reactor shutdown, and freezing of the cooling water in cold regions. Cooling water also reduces the thermal efficiency inside the reactor.

JP 2020-169735 A

In light of the above circumstances, the present invention aims to provide a heating furnace with a new structure that can suppress thermal deterioration of the sealing material arranged around the opening.

The heating furnace according to the first aspect of the present invention is defined as follows:
An opening formed in the furnace body for carrying in and/or carrying out the object to be heat-treated;
a seal member provided on a periphery of the opening and surrounding the opening;
A furnace door that moves up and down to open and close the opening;
A heating furnace comprising:
The oven door includes a frame member having a first surface that contacts the seal member when the opening is closed, and a second surface that extends inside the first surface in a direction intersecting the first surface,
At least a portion of the insulating material covering the second surface is made of a flexible blanket-like insulating material, and the blanket-like insulating material is provided flush with the first surface.

According to the heating furnace of the first aspect defined in this manner, the second surface side of the frame member that comes into contact with the sealing member is covered with insulating material, so that the sealing member is prevented from becoming too hot due to heat from inside the furnace being transmitted to the sealing member through the frame member of the furnace door, and thermal deterioration of the sealing member arranged around the opening can be suppressed.
Here, when the insulation material on the furnace door side is provided flush with the first surface, the gap between the furnace shell member on the opposing furnace body side and the insulation material on the furnace door side becomes small. Therefore, in the heating furnace of the first aspect, a flexible blanket-like insulation material is provided at a position flush with the first surface so that the insulation material is less likely to be damaged even if the insulation material on the furnace door side comes into contact with the furnace shell member on the furnace body side when the furnace door is raised or lowered.

The second aspect of the present invention is defined as follows:
In the heating furnace specified in the first aspect, a low thermal conductivity insulating material having a thermal conductivity of 0.045 [W/m/K] or less at 600°C is provided on the back side opposite the opening side of the blanket-like insulating material provided on the furnace door, so as to cover the second surface.
According to the heating furnace of the second aspect thus defined, the effect of the low thermal conductivity insulating material can further suppress the temperature rise of the sealing member.

The third aspect of the present invention is defined as follows:
In a second aspect, in a specified heating furnace, a lower seal member provided below the opening and a lower frame member of the furnace door in contact with the lower seal member are positioned between two adjacent rollers for transporting the material to be heat-treated.
When low thermal conductivity insulation material is used as described above, the insulating effect is high and the furnace door can be constructed compactly, making it easy to realize a layout in which the lower seal member and the lower frame member of the furnace door are positioned between two adjacent rollers for transporting the material to be heat treated.

The fourth aspect of the present invention is defined as follows:
In the heating furnace according to any one of the first to third aspects, the opening closing surface of the furnace door has a central region where the blanket-like insulating material is not provided, forming a recessed shape.
According to the heating furnace of the fourth aspect defined in this manner, a gap can be secured between the furnace door and the furnace shell members on the furnace body side in the central region of the furnace door, where the effect of suppressing the temperature rise of the sealing member is relatively small, and contact with the furnace shell members on the furnace body side in such central region can be avoided.

The fifth aspect of the present invention is defined as follows:
In the heating furnace according to any one of the first to fourth aspects, the blanket-like heat insulating material is connected to the iron shell via a stud,
The blanket-like insulating material has recesses formed therein, and the tip ends of the studs are received in the recesses.
According to the heating furnace of the fifth aspect thus defined, contact between the tip end of the stud and the furnace shell member on the furnace body side can be avoided.

The sixth aspect of the present invention is defined as follows:
In any one of the first to fifth aspects, in a specified heating furnace, the insulating material on the furnace body side located between the sealing member and the opening is made to protrude toward the furnace door side beyond the sealing member mounting surface to which the sealing member is attached, and when the furnace door is in a closed state, the insulating material on the furnace body side is brought into contact with the furnace door.
According to the heating furnace of the sixth aspect defined in this manner, it is possible to eliminate (or make extremely small) the gap in the insulating material that shields the opening and the sealing member when the furnace door is closed, thereby further preventing the sealing member from becoming too hot.

1 is a diagram showing a schematic configuration of a roller hearth heating furnace according to an embodiment of the present invention. 2 is a perspective view showing the opening periphery of the furnace body and the furnace door in the heating furnace, with the opening periphery and the furnace door separated from each other. FIG. 2 is a cross-sectional view showing the opening periphery of the furnace body and the furnace door in the heating furnace. FIG. This is a diagram showing the furnace door alone, where (A) is a front view seen from the opening blocking surface side, (B) is a cross-sectional view taken along line B-B of (A), and (C) is a cross-sectional view taken along line CC of (A). 6 is an explanatory diagram of the opening and closing operation of the furnace door in the heating chamber. FIG. FIG. 6 is an explanatory diagram of the opening and closing operation of the furnace door following FIG. 5 . 1A is a heat pattern obtained when investigating the temperature distribution of a sealing member and a heat treatment object, and FIG. 1B is a diagram showing measurement points when investigating the sealing member temperature. FIG. 2 is a diagram showing measurement points when investigating the temperature distribution of an object to be heat treated. FIG. 13 is a diagram showing a modified example of the embodiment.

Next, an embodiment of the present invention will be described in detail below.

Fig. 1 shows a schematic configuration of a roller hearth heating furnace according to one embodiment of the present invention. In the figure, reference numeral 1 denotes a roller hearth heating furnace (hereinafter, sometimes simply referred to as a heating furnace), which performs heat treatment on an object to be heat-treated, such as steel or ceramics, placed on a tray.
In the following, as shown in Figure 1, the vertically upward direction is referred to as the upward direction, the vertically downward direction is referred to as the downward direction, the downstream side of the direction in which the object to be heat-treated W is transported (loaded) into the heating furnace 1 is referred to as the forward direction, and the upstream side of the direction in which the object to be heat-treated W is transported into the heating furnace 1 is referred to as the backward direction.

As shown in FIG. 1, the heating furnace 1 has a steel furnace body 5. The furnace body 5 has heat-resistant insulation 6 inside, which constitutes the insulation wall 7. The inside of the insulation wall 7 is a heating chamber 10 that contains the object W to be heat-treated, and the heating chamber 10 is provided with a burner 12 and a stirring fan 14 as heating means. An opening 9 is formed on the right side of the furnace body 5 in the figure, through which the object W to be heat-treated is carried in and out, and heat treatment is performed on the object W to be heat-treated housed in the heating chamber 10 through the opening 9.

Inside the heating chamber 10 and in the area outside the furnace near the opening 9, multiple transport rollers 20 are arranged side by side along the forward and backward direction, which is the transport direction. In the figure, 21 is a drive motor for rotating the rollers 20. By rotating the drive motor 21 in the forward direction, the object W to be heat-treated is brought into the furnace, and by rotating the drive motor 21 in the reverse direction, the object W to be heat-treated is taken out of the furnace.

The opening 9 is provided with a furnace door 25 that is raised and lowered vertically by an opening/closing device 24 to open and close the opening 9. In FIG. 1, the furnace door 25 in the closed state is shown by a solid line, and the furnace door 25 in the open state is shown by a two-dot chain line.

17 is a pressing device provided near the furnace door 25. Based on the driving force from a motor or the like (not shown), the link 17b swings around the rotating shaft 17a, and the furnace door 25 in the closed state is pressed against the opening 9.

Fig. 2 is a perspective view showing the periphery of the opening of the furnace body 5 and the furnace door 25 in a separated state. Fig. 3 is a cross-sectional view showing the periphery of the opening of the furnace body 5 and the furnace door 25 in a separated state.
As shown in Fig. 2, a seal member 16 that keeps the inside of the furnace airtight by contacting the furnace door 25 is attached to the periphery of the opening 9 formed in the furnace body 5 so as to surround the opening 9. In more detail, as shown in Fig. 3, the seal member 16 is attached to a seal member mounting surface 41a of a metal furnace shell member 41 arranged around the opening 9.
In this embodiment, a rope-like seal member made of heat-resistant ceramic fiber and rubber binder is used as the seal member 16. The heat-resistant temperature of the seal member 16 is approximately 500°C.

Next, the configuration of the furnace door 25 that closes the opening 9 will be described. The furnace door 25 comprises a frame member 27, an iron shell 28, and a heat insulating material section 30, and is generally shaped like a rectangular plate as shown in FIG. 2. When the furnace door 25 is viewed from the side, the iron shell 28 near the lower side of the frame member 27 (lower frame member 34) is tapered so as not to interfere with the roller 20 located on the rear side (see FIGS. 1 and 5).

The frame member 27 is a rectangular frame-shaped ring-shaped body made of rectangular cylindrical metal pipes, and is integrally joined to the peripheral edge of the iron shell 28. As shown in FIG. 3, the frame member 27 has a first surface 27a that faces the sealing member 16 on the furnace body side and contacts the sealing member 16, and a second surface 27b that is perpendicular to the first surface 27a on the inside of the first surface 27a (the side facing the center of the furnace door 25).

As shown in Figure 3, the insulation section 30 is defined by the frame member 27 and the iron shell 28 and is made up of multiple insulation materials 30a, 30b, 30c, and 30d stacked in a storage space 29 that is open to the opening 9 of the furnace body 5, and closes the opening 9 of the furnace body 5 when the furnace door is closed.
The material for these heat insulating materials is not particularly limited, but may be a refractory material with a high porosity, ceramic fiber or ceramic particles in the form of a board or a flexible blanket, or the like.

As shown in FIG. 3, the heat insulating material 30 is disposed in the peripheral region 31 close to the frame member 27 so as to cover the second surface 27b of the frame member 27. More specifically, the heat insulating material is disposed up to the same height as the first surface 27a so as to cover the corner where the first surface 27a and the second surface 27b of the frame member 27 intersect. If the second surface 27b of the frame member 27 is exposed, the frame member 27 will be heated through the exposed portion, and the temperature of the seal member 16 in contact with the frame member 27 will increase.

In this example, a low thermal conductivity insulating material 30a having a thermal conductivity of 0.045 [W/m/K] or less at 600° C. is used as the insulating material covering the second surface 27b of the frame member 27. This effectively prevents the temperature of the heating chamber 10 from being transferred to the frame member 27. The thermal conductivities of the insulating materials 30b, 30c, and 30d other than the low thermal conductivity insulating material 30a used in this example are 0.15 to 0.25 [W/m/K] at 600° C.
The low thermal conductivity insulating material 30a may be, for example, a microporous insulating material in which the void size between particles is reduced using ceramic particles of a micron order or less. The low thermal conductivity insulating material with a microporous structure is more brittle than other insulating materials and has a problem of being easily broken. For this reason, in this embodiment, the surface of the low thermal conductivity insulating material 30a is covered with a blanket-like insulating material 30b to prevent the low thermal conductivity insulating material 30a from being damaged.

On the other hand, in the region inside (closer to the center) than the low thermal conductivity insulating material 30a, blanket-shaped insulating material 30d is layered, and board-shaped insulating material 30c is layered on its surface. The board-shaped insulating material 30c is layered so that it is flush with the low thermal conductivity insulating material 30a. The peripheral portion of the board-shaped insulating material 30c is further covered with blanket-shaped insulating material 30b. As a result, the opening blocking surface 26 of the furnace door 25 has a concave shape in which the central region 32 where the blanket-shaped insulating material 30b is not arranged is recessed compared to the peripheral region 31 where the blanket-shaped insulating material 30b is arranged.

As shown in FIG. 3, these stacked insulation materials 30a, 30b, 30c, and 30d are connected via studs 35, one end of which is joined to the steel shell 28. More specifically, a flange-shaped member 36 is screwed to the tip end 35b of the stud 35, which extends toward the furnace body 5, and the insulation material is sandwiched between the steel shell 28 and the flange-shaped member 36. In this example, a recess 37 is formed in the blanket-shaped insulation material 30b, and the tip end 35b of the stud 35 is accommodated in the recess 37. This is to prevent the tip end 35b of the stud 35 from interfering with the furnace shell member when the furnace door is raised and lowered.

The structure of the furnace door 25 has been explained above using the upper and lower parts of the furnace door 25 shown in Figure 3 as examples, but the left and right parts of the furnace door 25 shown in Figure 4 (C) also have similar characteristics.

Next, the heat insulating material disposed near the opening 9 on the furnace body 5 side will be described. As shown in Fig. 3, on the furnace body 5 side, heat insulating material is provided so as to shield the space between the furnace shell member 41 to which the seal member 16 is attached and the heating chamber 10, and between the furnace shell member 41 and the opening 9. A part of the heat insulating material is a low heat conductive heat insulating material 42a having a heat conductivity of 0.045 [W/m/K] or less at 600°C, as in the case of the furnace door 25.
In the furnace shell member above the opening 9, the low thermal conductivity insulating material 42a is plate-shaped in cross section extending horizontally (front-back direction) between the opening 9 and the furnace shell member 41. On the other hand, in the furnace shell member below the opening 9, the low thermal conductivity insulating material 42a extends vertically between the furnace shell member 41 and the heating chamber 10, and is generally T-shaped in cross section extending horizontally (front-back direction) between the opening 9 and the furnace shell member 41. In this example, the cross-sectional shape of the low thermal conductivity insulating material 42a is different between the upper side and the lower side of the opening 9 in consideration of the difference in thickness of the insulating material 42c. However, for example, as shown in the partially enlarged view of FIG. 3, the cross-sectional shape of the low thermal conductivity insulating material 42a on the upper side can be generally T-shaped in cross section like the lower side. In some cases, both can be plate-shaped in cross section.
The low thermal conductivity insulating material 42a is layered together with other blanket-like insulating materials 42b, 42c, etc., and one end is connected to an iron shell (not shown) via a stud 35.

5 and 6 are explanatory diagrams of the opening and closing operation of the furnace door 25 in the heating furnace 1.
As shown in FIG. 5, in the heating furnace 1 of this embodiment, a lower seal member 19 is provided below the opening 9 and between two adjacent conveying rollers 20, 20.
5, the furnace door 25 is first raised to the position shown by the two-dot chain line when the heat treatment object W is carried in and out, and then, after the heat treatment object W has passed through the opening 9, it is lowered downward to a predetermined position where the opening closing surface 26 of the furnace door 25 faces the opening 9. At this time, the lower frame member 34 of the furnace door 25, which is in contact with the lower seal member 19, is positioned between two adjacent conveying rollers 20, 20.

Then, as shown in FIG. 6, the furnace door 25 is pressed against the opening 9 by the pressing action of the link 17b of the pressing device 17 (see FIG. 1), and the first surface 27a of the frame member 27 of the furnace door 25 comes into contact with the sealing member 16, ensuring airtightness inside the furnace. At this time, the space between the heating chamber 10 and the opening 9 and the sealing member 16 is shielded by insulating material except for the gap δ portion, so that the temperature of the sealing member 16 due to heat from inside the furnace is prevented from increasing.

Next, the results of investigations into the temperature of the sealing member in the heating furnace 1 and the temperature distribution of the object W being heat-treated in the heating chamber will be described.
The temperature of the sealing member was investigated by heating the heating chamber 10 in an _N2 atmosphere with the heat pattern shown in Fig. 7(A) and checking how high the temperature of the sealing member 16 rose to. The temperature measurement points P were the eight points shown by black circles in Fig. 7(B), and the temperature measurements were performed using sheathed thermocouples.
As a result of the investigation, the maximum temperatures at each measurement point were 149°C to 234°C, which were sufficiently low compared to the heat resistance temperature of the seal member 16, which is 500°C.

The temperature distribution of the object W to be heat-treated was investigated by loading a total of 10 objects W to be heat-treated (wire coils) in two layers into the heating chamber 10 as shown in Fig. 8, heating the heating chamber in a _N2 atmosphere with the heat pattern shown in Fig. 7(A), and checking the temperature distribution of the object W to be heat-treated at the end of the soaking at 900°C. The temperature was measured at 12 points P indicated by black circles in Fig. 8, and the temperature was measured using a sheathed thermocouple.
As a result of the investigation, the temperature variation at the 12 measurement points was found to be 6.6°C.
Furthermore, under the same conditions, when a water-cooling method was adopted in which water was circulated inside the frame member 27 on the furnace door 25 side that comes into contact with the sealing member 16 to cool the sealing member 16, the range of temperature variation at the 12 measurement points was 8.1 to 9.2°C. Therefore, it can be seen that the configuration of this embodiment, which suppresses the temperature of the sealing member 16 without water cooling, is also excellent in terms of temperature uniformity.

As described above, according to the heating furnace 1 of this embodiment, the second surface 27b side of the frame member 27 that comes into contact with the sealing member 16 is covered with insulating material, so that the sealing member 16 is prevented from becoming too hot due to the heat inside the furnace being transmitted to the sealing member 16 through the frame member 27 of the furnace door 25, and thermal deterioration of the sealing member 16 arranged around the opening 9 can be suppressed.
In this embodiment, the insulation material on the furnace door 25 side is provided flush with the first surface 27a, so that the gap between the furnace door 25 side and the furnace shell member on the opposing furnace body side is small. Therefore, in this embodiment, a flexible blanket-shaped insulation material 30b is provided flush with the first surface 27a so that the insulation material is less likely to be damaged even if the furnace door 25 comes into contact with the furnace shell member on the furnace body side when the furnace door is raised or lowered.

In the heating furnace of this embodiment, a low thermal conductivity insulating material 30a with a thermal conductivity of 0.045 [W/m/K] or less at 600°C is provided on the rear side of the blanket-like insulating material 30b provided on the furnace door 25, opposite the opening 9, so as to cover the second surface 27b. This low thermal conductivity insulating material 30a can further prevent the sealing member 16 from becoming too hot.

When low thermal conductivity insulating material 30a is used, the insulating effect is high and the furnace door 25 can be constructed compactly, making it easy to realize a layout in which the lower seal member 19 and the lower frame member 34 of the furnace door 25 are placed between two adjacent conveying rollers 20, 20.

As shown in FIG. 3, in the heating furnace of this embodiment, the central region 32 where the blanket-like insulating material 30b is not arranged on the opening closing surface 26 of the furnace door 25 is recessed. Therefore, for the central region 32, which has a relatively small effect in suppressing the temperature rise of the sealing member 16, a gap can be secured between the furnace shell member on the furnace body 5 side, and contact with the furnace shell member on the furnace body side in the central region 32 can be avoided.

FIG. 9 shows a modification of the above embodiment.
In this example, as shown in Figure 9 (A), the insulating materials 42a and 42b on the furnace body 5 side, which are located between the sealing member 16 and the opening 9, are made to protrude toward the furnace door 25 side further than the sealing member mounting surface 41a to which the sealing member 16 is attached, and when the furnace door is in the closed state shown in Figure 9 (B), the end faces 50 of the insulating materials 42a and 42b are able to come into contact with the furnace door 25.
In this way, the gap δ (see Figure 6) between the end of the opening 9 and the furnace door 25 that existed in the above embodiment can be eliminated, thereby further suppressing the temperature rise of the sealing member 16.

The above is a detailed description of an embodiment of the present invention, but this is merely an example. For example, instead of a rectangular cylindrical member, a solid square timber or a plate material bent into an L shape can be used as the frame member of the furnace door that comes into contact with the sealing member. Also, while the above embodiment is an example in which one opening is provided in the furnace body, the present invention can also be applied to a continuous heating furnace with two openings, one for loading and one for unloading, and the present invention can be configured in various modified forms without departing from the spirit of the invention.

REFERENCE SIGNS LIST 1 roller hearth type heating furnace 5 furnace body 9 opening 16 sealing member 20 roller for transporting material to be heat treated 25 furnace door 27a first surface 27b second surface 28 iron shell 30 heat insulating material portion 30a low thermal conductivity insulating material 30b blanket-like insulating material 31 peripheral region 32 central region 35 stud 35b tip end portion 37 recess 41a sealing member mounting surface 42a low thermal conductivity insulating material W material to be heat treated

Claims (6)

An opening formed in the furnace body for carrying in and/or carrying out the object to be heat-treated;
a seal member provided on a periphery of the opening and surrounding the opening;
A furnace door that moves up and down to open and close the opening;
A heating furnace comprising:
The oven door includes a frame member having a first surface that contacts the seal member when the opening is closed, and a second surface that extends inside the first surface in a direction intersecting the first surface,
A heating furnace, wherein at least a portion of the insulating material covering the second surface is made of a flexible blanket-like insulating material, and the blanket-like insulating material is provided flush with the first surface. The heating furnace according to claim 1, wherein a low thermal conductivity insulating material having a thermal conductivity of 0.045 [W/m/K] or less at 600°C is provided on the rear side of the blanket-like insulating material provided on the furnace door, opposite the opening side, so as to cover the second surface. The heating furnace according to claim 2, in which the lower seal member provided below the opening and the lower frame member of the furnace door that contacts the lower seal member are disposed between two adjacent rollers for transporting the object to be heat-treated. The heating furnace according to any one of claims 1 to 3, wherein the opening closing surface of the furnace door has a recessed central area where the blanket-like insulation material is not provided. The blanket-like insulation material is connected to the iron shell via studs,
5. The heating furnace according to claim 1, wherein said blanket-like insulating material has recesses formed therein, and said tip ends of said studs are received in said recesses. The heating furnace according to any one of claims 1 to 5, in which the heat insulating material on the furnace body side located between the seal member and the opening is protruded toward the furnace door side beyond the seal member mounting surface on which the seal member is attached, and the heat insulating material on the furnace body side is in contact with the furnace door when the furnace door is closed.

Images