JPS61180608A - Heat retaining cover of high temperature steel - Google Patents

Abstract

PURPOSE:To suppress lowering of temperature of high temperature steel material being carried and enable to observe inside of the cover by arranging heat retaining covers using selective light absorbing film above and below a carrying line of high temperature steel material. CONSTITUTION:Heat retaining covers 2, 3, 4 that cover above a carrying line are provided symmetrically to the center of the carrying line. The cover 2 is provided horizontally to the carrying line, and the cover 3 is provided to project in V-shape at the center of the carrying line. The cover 4 is circular arc-shaped and placed to converge reflected light H of the high temperature steel 1 to edge parts 1b, 1c. The cover 4 is turnable around a fulcrum 32 and converges the reflected light to edge parts 1b, 1c. Covers 2, 3 are provided with a selective light absorbing film 16 on inner surface of heat resisting material 17, and a heat resisting glass 15 is provided on the surface to prevent oxidation of the heat resisting material 17 and increase of heat absorption of the cover. Backside of the heat resisting material 17 is reinforced with a heat insulating material and an iron shell 18. The cover 3 is formed combining the heat resisting glass 15 and selective light absorbing film 16. The cover 4 is constituted similarly with the cover 2, and covers 7, 8 are constituted similarly with the cover 3.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement of a heat insulating cover for a conveyance line for high temperature steel materials.

(Prior art) Places where high-temperature steel materials such as slabs pass on a conveyor line,
For example, on hot rolling or thick plate rolling lines, high-temperature steel materials are exposed to the atmosphere for a long time, resulting in a large temperature drop during conveyance, and this tendency is particularly noticeable at the edges of the steel materials. This temperature drop causes a temperature deviation within the product, which deteriorates the quality especially at the edges, so the edges are cut to ensure quality, which greatly affects the yield. Also,
In the heating furnace, the heating extraction temperature is set high in advance to ensure a certain quality in consideration of the temperature drop of the steel material during transportation, which greatly affects the fuel consumption rate of the heating furnace.
There is no choice but to operate in a manner that is contrary to energy conservation.

As countermeasures against these problems, there are several methods: installing a heat insulating cover on the conveyance line, and heating the steel material being conveyed using a burner or electromagnetic induction.

The latter heating method suppresses the temperature drop in the steel material, leading to improved yield and fuel consumption in the heating furnace, but it consumes a large amount of fuel and electricity, making it difficult to achieve overall energy savings. When installing, sufficient consideration must be given to equipment structure, maintenance, etc.

Furthermore, regarding the former method of installing a heat insulating cover on the conveyor line, the techniques shown in FIGS. 9, 10, and 11 are disclosed in Japanese Patent Application Laid-open No. 58-210115 and Japanese Patent Application Laid-open No. 58-224.
No. 019 and Japanese Utility Model Application No. 56-1655σ8 are official seals, and examples are known in which a low emissivity plate (highly reflective), such as a stainless steel plate, is used on the surface of the heat-insulating cover.

In the example shown in FIGS. 9 and 10, stainless steel plates are used on the surfaces of the lower heat retaining covers 22 and 23 to suppress the heat of the high-temperature steel material l from being transferred to the conveyor roll 6, or However, with these methods, the surface of the stainless steel plate or stainless steel plate is gradually oxidized when used in a high temperature range, and the surface emissivity increases, causing the heat insulating cover (chin There is a drawback that the heat retention effect decreases due to the increase in the amount of heat.

Further, the heat insulating cover characterized by having a heat insulating cover reflective protrusion described in Japanese Utility Model Application Publication No. 56-165508 shown in FIG. The heat wire H from the high temperature steel material 1 on the conveyor roll 6 is connected to the heat insulating cover 25a.
, 25b, the heat collecting curved surface 2 is reflected by the reflective protrusions 27 am 27 b and connected by the flat plate parts 26a and 26b.
Since it is reflected downward by Ba, 28b, moving devices 292, 29b are provided to guide it to the vicinity of the edge portion 1' of the high-temperature steel material 1 even if the width dimension of the high-temperature steel material 1 changes, making it possible to move in the direction of the arrow. , an opening may be formed in the reflective protrusion 5, and since there is no heat insulating material placed on the back, the amount of heat dissipated from the heat retaining part is large, and the heat retaining performance is inferior to that using a heat insulating material. Also, since the entire conveyance line is covered with a reflective surface, it is impossible to visually see the position of the steel material being conveyed, and in the event of an abnormality such as a failure of the conveyor rolls, detection may be delayed, which could lead to a serious accident. .

(Problems to be Solved by the Invention) The present invention aims to improve the above-mentioned drawbacks.In a conveyance line for high-temperature steel materials such as slabs, a light-selective absorption film is placed on the inner surface of a heat-insulating cover facing the high-temperature steel materials. By implementing efficient heat insulation, the objective is to suppress the temperature drop during transportation of high-temperature steel materials, improve the fuel consumption rate of the heating furnace, improve yield, and visualize the inside of the heat insulation cover.

In thermal covers placed on high-temperature steel transport lines,
A heat insulating cover for high temperature steel material, characterized in that a light selective absorption film that absorbs and transmits visible light and reflects infrared light is arranged on the inner surface of a heat resistant material of the heat insulating cover, and a heat insulating cover disposed on a conveyance line for high temperature steel material. In the cover, a light-selective absorption film that absorbs and transmits visible light and reflects infrared light is arranged on the inner surface of the heat-resistant material of the heat-insulating cover, and a part of the heat-insulating cover has a structure in which heat-resistant glass and a light-selective absorption film are combined. This heat-insulating cover is made of high-temperature steel material and is characterized by the fact that the inside of the heat-insulating cover is visible.

(Function) Hereinafter, the heat insulating cover for high-temperature steel materials of the present invention will be described in detail based on the embodiments shown in the drawings.

First, the light selective absorption film will be explained. A light selective absorption film is a thin film that has the property of absorbing and transmitting light of a certain wavelength and reflecting light of other wavelengths.

Hereinafter, the principle of the light selective absorption film will be described. The wavelength of maximum radiant energy emitted from a high temperature object such as a slab is generally expressed by Wien's displacement law of equation (1).

λtnaX″T= 2897.8 (am, K)・
...-(1) λmax (μm): Wavelength of maximum radiant energy T (K): Absolute temperature For example, the wavelength of coffin-sized radiant energy emitted from an object at 1000°C is calculated by modifying equation (1). Therefore, it is expressed as 2897, 8 λmax=□ 2.28 Cμm-K )・= (21.Also, Figure 6 shows the change in maximum radiant energy at multiple temperatures. (727℃)~
Approximately 2μr in the temperature range of 1200K (927℃)
Since the energy distribution has a maximum value in the range called the infrared light region of n or more, this region, that is, approximately 2 μm
The key to highly efficient heat retention is to reflect light with wavelengths above.

In order to visualize the inside of the thermal cover, any material that absorbs and transmits visible light present in moths with a wavelength of less than approximately 2 μm may be used.

Therefore, in order to efficiently insulate high-temperature steel materials near 1000℃, which is the purpose of this study, and to visualize the inside of the insulation cover, it is necessary to reflect light with a wavelength of approximately 2 μm or more, and to
The absorbing film may be selected in a manner that absorbs and transmits light having a wavelength of m or more.

FIG. 5 is a diagram showing the principle of a light selective absorption film. In FIG. 5, when the radiant heat 19 emitted from the high-temperature steel material 1 at 1000°C reaches the light absorption layer 16 on the inner surface of the heat insulation cover 3, the light 20 with a wavelength of 2 μm or more in the infrared light region is The reflected light 21 having a wavelength in the visible range of less than 2 μm is absorbed and transmitted by the heat-resistant glass 15 .

Figures 1 and 2 show an example in which a heat insulating cover is installed on the hot strip of a hot rolling line. FIG. 1 is a partially cutaway perspective view, and FIG. 2 is a sectional view in the direction of high-temperature steel material conveyance. The heat insulation cover is the upper heat insulation cover 2.3 facing the high temperature steel material l.
．． It consists of a side heat insulating cover 4, a lower heat insulating cover 8, and a heat insulating cover 7 for protecting the transport roll from heat, all of which have a light selective absorption film 16t arranged on the inner surface facing the high temperature steel material 1. .

The heat insulating cover 7 for protecting the transport roll from heat is supported by the pillars 10, and prevents deformation and fatigue of the roll due to the rise in temperature of the roll due to heat radiation and conduction from the high m steel material l to the transport roll 6, and also has a heat retaining effect. In order to increase the height, the rollers are provided so as to cover the roll at the front and rear of the roll in the roll axis direction. The lower heat insulation cover 8 is supported by struts 11, and reflects heat radiation from the center part 1°a of the steel material intensively to the edge parts 1b and Ic of the steel material, which generally have a larger temperature drop than the center part, thereby reducing the temperature drop at the edge part. The central part of the conveyor line is set between the conveyor rolls in order to suppress this and to provide an appropriate angle in consideration of the evacuation of the scale (e-ferrous iron) that falls during conveyance, and to allow the scale to fall smoothly downward. It is installed in a plate shape so that the apex is symmetrically tilted in the direction of the roll axis. Of course, the heat insulating cover 4.8 can be adjusted in the roll axis direction so that radiant heat is concentratedly reflected at the edge of the steel material even for steel materials of different dimensions.
It is movable.

An upper heat-insulating cover 2.3 and a side heat-insulating cover 4 are provided symmetrically with respect to the center of the transport line so as to cover the upper part of the transport line. The upper heat retaining cover 2.degree.3 is integrally attached, with the heat retaining cover 2 being provided horizontally to the conveyance line, and the cover 3 being provided so as to protrude in the shape of a square in the center of the conveyance line.

The shape of the side heat retaining covers 4 is arcuate, and each cover is arranged so as to concentrate the reflected light H of the high temperature steel material on the edge portion 1bslc. The side heat insulating cover 4 can also be rotated about a fulcrum 32 by remote control by an automatic elevator 12, so that it can respond to changes in width and concentrate reflected light on the edge portion. The whole heat-insulating cover consists of a large number of circularly divided heat-insulating covers 2.3.4, which are struts 31, and a heat-insulating cup Z below the conveyor roll. g are supported by struts 10 and 11, respectively.

FIG. 4 shows the heat insulating cover 2.
3.4.8 is a diagram showing an example of how heat is radiated to the edge portions 1b and 1c, the upper surface of the steel material is reflected by the protrusion of the heat insulation cover 3, the lower surface of the steel material is reflected by the lower heat insulation cover 8,
The reflected light H is concentrated on the edge portions 1b and Ic.

FIG. 3 shows the upper heat retaining cover 2 of the heat retaining cover according to the present invention.
FIG. 3 is a diagram illustrating details using a part of FIG. A light selective absorption film 16 is arranged on the inner surface of a stainless steel plate (SUS 310) 17, which is a heat-resistant material, and a heat-resistant glass 1 is placed on the surface.
5 is arranged to prevent oxidation of the stainless steel plate 17 and an increase in the amount of heat absorbed by the cover. The back side of the stainless steel plate 17 is insulated with a heat insulating material (ceramic fiber), and the entire cover is reinforced with an iron skin 18 and finished with a selt 13.

In addition, in order to visualize the inside of the heat insulation cover, the upper heat insulation cover 3 is installed on an arm 14 attached to the upper heat insulation cover 2, and a heat-resistant glass 15 and a light selective absorption, an odor 1
6 are arranged in combination.

The structure of the side heat insulating cover 4 is also the same as that of the top heat insulating cover 2, and the structure of the heat insulating cover 7 for transport roll heat protection and the bottom heat insulating cover 8 is the same as that of the top heat insulating cover 3.

Examples of materials for the light selective absorption film include molybdenum (MO), alumina (AtzOs), indium oxide (InzOs), and specially treated stainless steel plates, but as shown in the example shown in Figure 7, Since there is a close relationship between the film thickness and reflectance of the photo-selective absorption film, it is necessary to select the material and film thickness with due consideration to the durability of the photo-selective absorption film. The heat-resistant glass, metal plate, and other materials used for the heat-insulating cover suppress heat absorption to the heat-insulating cover as much as possible.
In order to enhance the heat retention effect, it is desirable to use a material that has as low a thermal conductivity as possible and is as thin as possible while taking durability into consideration.

It goes without saying that the heat insulating cover according to the present invention can be installed on a conveyance line for not only plate-shaped high-temperature steel materials such as slabs but also long steel, and has a heat insulating effect.

(Example) An example in which the present invention was applied to hot strip insulation on a hot rolling line is shown below.

The heat insulating cover according to the present invention was installed on a hot rolling line over a distance of approximately 501n between a rough rolling mill and a finishing rolling mill. The structure of the heat retaining cover is similar to that shown in FIGS. 1 to 3. An alumina film was used as the light selective absorption film and was placed on the entire inside of the heat insulation cover. A hot strip with a thickness of 50%, a width of 2 mm, and a length of 5011 mm was used to confirm the heat retention effect of the heat insulation cover. The evaluation was performed by measuring the @ variation distribution in the immediate vicinity of the exit side using a radiation-type temperature fraction processing device.

FIG. 8 shows the temperature distribution at the outlet of the heat insulation cover in the width direction of the hot strip in each state.

Songs in Figure 8 +1! Ja is one curve after installing the thermal cover related to this BA, and after installing the conventional type thermal cover that uses ceramic fiber on the inner surface of the cover, the song, li! c.
are the respective surface temperature distributions before the heat insulation cover was installed.

With the thermal cover installed [m (C), the average temperature in the strip width direction was 1043°C, but after installing the main thermal cover (a) it was 1051°C, and the average thermal insulation effect of the thermal cover using photo-selective absorption pIXft was 8. Friends at ℃. In addition, the effect of uniformizing the temperature in the strip width direction, that is, the effect of suppressing the temperature drop due to active heating of the strip edge, is 1
The temperature was 8°C. Heat-resistant glass 15. In the case of the conventional type heat-retaining cup 9- (curve b) in which the light selective absorption film 16 and the stainless steel plate 17 are removed and ceramic fins are placed on the inner surface of the heat-retaining cover, the amount of heat absorbed by the cover increases and the heat retention Compared to the case without the cover, the overall heat retention effect was 2°C, and the heat retention effect at the strip edge was 4°C. Therefore, this thermal cover using a light-selective absorption film has an average thermal insulation effect of 6C compared to the conventional type thermal cover.
The heat retention effect of the strip joint is 14°C. Table 1 summarizes the results of the above heat retention effect.

By the way, the quality of hot-rolled products is mainly related to the strip temperature at the exit of the finish rolling mill. If a temperature above the Ar transformation point can be maintained throughout the strip, quality deterioration such as cracking at the edges and lack of strength can be prevented. can be reduced.

For this reason, as long as the temperature above the Ar3 transformation point is ensured by this heat insulation cover installation (a), the heating extraction temperature of the heating furnace, which corresponds to the heat retention effect formula, can be lowered, so it is possible to improve the heating furnace fuel consumption rate. is possible.The average fuel consumption rate of the heating furnace before installing this insulation cover is approximately 203×10
"kcat/T," but by lowering the extraction temperature by about 8℃ due to the insulation effect of the conveyor line strip by installing this insulation cover, the average heating furnace fuel consumption rate tr'l has been reduced.
198 x 103kcat/T, approximately 5 x 10
We were able to achieve an improvement of 3kcat/T.

Furthermore, by using a heat-retaining cover that combines heat-resistant glass and a light-selective absorption film in the center of the heat-retaining cover for the purpose of visualizing the inside of the cover, the position of high-temperature steel can be clearly confirmed when it passes through, and the inside of the cover can be visualized. It was realized.

(Effects of the Invention) By installing the heat insulating covers of the present invention using a light selective absorption film above and below the conveyance line for high temperature steel materials, it is possible to suppress the temperature drop of the high temperature steel materials during conveyance, especially at the edge portions, As a result, it is possible to lower the heating furnace extraction temperature (low-temperature heating), and it is expected to achieve significant energy savings.By utilizing the characteristics of the light-selective absorption film and combining it with heat-resistant glass, it is possible to Internal visualization becomes possible,
The present invention has great effects, such as being able to monitor abnormalities such as accidents inside the cover.

[Brief explanation of drawings]

Fig. 1 and Fig. 2 show an example in which the heat insulating cover according to the present invention is installed in a holatos scoop of a hot rolling line, Fig. 1 is a partially cutaway perspective view, and Fig. 2 is a high temperature steel material conveyance. 3 is a diagram showing details of a part of the upper heat insulation cover of the heat insulation cover according to the present invention (as an example), FIG. 4 is a diagram showing an example of heat radiation, and FIG. 5 is a diagram showing the light selection. Figure 6 is a diagram showing the change in maximum radiant energy at each temperature. Figure 7 is a diagram showing the relationship between the film thickness and reflectance of the light-selective absorption film. Figure 8 is the width of the hot strip. 9, 10 and 11 are diagrams showing examples of conventional heat insulation covers. 1...High temperature steel material, 1'...Edge part , 1.!・
... Steel material center portion, 1b, 1c... Steel material edge portion, 2.
3-...Top heat retention cover, 4...Side heat retention cover, 5
... Reflective protrusion, 6 ... Transport roll, 7 ... Heat insulation cover for transport roll heat protection, 8 ... Lower part heat insulation cover, 9
... Conveyance roll bearing, 10... Support, 11... Support, 12-... Automatic elevator, 13... Bolt, 14...
...Arm, 15...Heat-resistant glass, 16...Selective light absorption film, 17...Stainless steel plate, 18...Iron skin, 1
9...Radiant heat, 20...Light with a wavelength in the infrared region, 2
1...Light in visible wavelength range, 22.23...Lower heat insulation cover, 24 aae stainless steel pipe s 25
a*25b... Heat insulation cover, 26a, 26b... Flat plate part, 27a, 27b... Reflective protrusion, 28a, 28b
...Heat collection curved surface % 29a* 29b-...Movement device,
31... Support, 32... Fulcrum. Agent Patent Attorney Masamitsu Akizawa and 2 others - NXM Kosho Rugi" - EK Jumen m', ph Name of Patent Application No. 1982-21090: Heat insulation cover 3 made of high-temperature steel materials, person making the amendment Relationship to the case Applicant address (residence) 2-6-3 Otemachi, Chiyoda-ku, Tokyo Name (name) (665) Nippon Steel Corporation Residence Taiyo Building, 12-1 Nihonbashi Kabuto-cho, Chuo-ku, Tokyo (Detailed explanation) and contents of the original drawings Contents of the amendment as shown in the attached sheet 1. Scope of claims of the present patent application All corrections are made as follows: (1) Heat retention capacity, S-
Insulation cut-0 for high-temperature steel material, characterized in that a light-selective absorption film that absorbs and transmits visible light and reflects infrared light is disposed on the inner surface of the heat-resistant material of the heat-retention cutter. (2) High-temperature steel material In a heat-retaining cutter disposed on a conveyance line, a light selective absorption film that absorbs and transmits visible light and reflects infrared light is disposed on the inner surface of a heat-resistant material of the heat-retaining cutter,
A heat-retaining cover made of high-temperature steel material, characterized in that a part of the heat-retaining commer has a structure that combines heat-resistant glass and a light selective absorption film to visualize the inside of the heat-retaining cover. 2. Amend "The method is known." in the fourth line from the bottom of the second page of the specification to "The method is known." 3 "Extraction temperature" and "Extraction temperature reduction" at the end of page 15 of the same
and correct it. 4. Change "Visualization is possible" on page 16, line 4 of the same page to "
I am trying to visualize it.''

Claims (2)

[Claims] (1) A heat-insulating cover disposed on a high-temperature steel transport line, characterized in that a light-selective absorption film that absorbs and transmits visible light and reflects infrared light is disposed on the inner surface of the heat-resistant material of the heat-insulating cover. thermal cover. (2) In a heat insulating cover placed on a conveyance line for high temperature steel materials, a light selective absorption film that absorbs and transmits visible light and reflects infrared light is arranged on the inner surface of the heat resistant material of the heat insulating cover, and a part of the heat insulating cover is A heat-insulating cover made of high-temperature steel material that is characterized by a structure that combines heat-resistant glass and a light-selective absorption film, making the inside of the heat-insulating cover visible.