JP2001194070A - Furnace cover for electric furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability of the furnace cover for an electric furnace to prolong the life. SOLUTION: A heat resisting and corrosion resistant zirconia-based ceramics thermal spraying layer B is formed through a cermet thermal spraying layer A absorbing thermal expansion, at least at the inside face of a water tube panel 2 in which a cooling water passage is formed in the furnace cover body 1. Further, a spark-resistant aluminium oxide-based ceramic thermal spraying layer C having a high insulation property is formed on the zirconia based ceramics thermal spraying layer B of the inside face of the water tube panel 2 in the vicinity of an electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a furnace lid for an electric furnace having a water-cooled structure.

[0002]

2. Description of the Related Art A furnace lid of a conventional electric furnace has a water-cooled structure, and a plurality of water tubes are juxtaposed to form a panel.
o There are a tube type, a water cooling jacket type in which a space in the panel is partitioned by a partition plate to form a cooling water passage, and a membrane type in which a plurality of water tubes are connected to each other by fins to form a panel.

[0003]

However, in the electric furnace, the temperature of the molten metal due to the scouring reaction is about 1600 ° C., the temperature of the reaction gas becomes about 1300 ° C., and since the furnace is exposed to the radiant heat and the gas flow accompanied with dust, the water cooling is performed. However, there is a problem in that oxidation, corrosion, and abrasion due to high temperatures are severe and the life is short.

[0004] It is an object of the present invention to solve the above problems and to provide a furnace lid for an electric furnace which can have a longer life.

[0005]

According to a first aspect of the present invention, there is provided a first thermal spraying layer for absorbing thermal expansion on at least an inner surface of a water cooling panel in which a cooling water passage is formed in a lid body. , A second sprayed layer made of a ceramic material having heat and corrosion resistance is formed, and a third sprayed layer having spark resistance is formed on the second sprayed layer on the inner surface of the water-cooled panel near the electrodes.

[0006] According to the above structure, a heat-resistant and corrosion-resistant ceramic material is exposed to the radiant heat of the high-temperature molten metal by the scouring reaction, and the inner surface of the water-cooled panel is brought into contact with the gas flow accompanied by the dust through the first sprayed layer. Since the second sprayed layer made of is formed, the ceramic layer of the second sprayed layer can be stably fixed to the surface of the metal water tube panel, and the heat resistance, corrosion resistance, and wear resistance are improved, and the life is improved. Can be done. Further, a third sprayed layer is provided so as not to generate a spark between the electrode and the water-cooled panel, thereby preventing the panel from burning and contributing to a longer life.

According to a third aspect of the present invention, in the above structure, a large number of studs are provided on the inner surface of the water-cooled panel to assist the formation of the slag layer, and the surfaces of these studs are also provided with the first sprayed layer. Thus, the second sprayed layer is formed. According to the above configuration, the first and second sprayed layers are also formed on the stud, whereby the durability of the stud can be improved, and the slag scattered by the scouring reaction is deposited to form a slag layer. This can contribute to prolonging the life of the furnace lid.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Here, the electric furnace Tu according to the present invention is described.
An embodiment of a be To Tube furnace lid will be described with reference to FIGS. This furnace lid is configured by connecting a plurality of water pipe panels (water cooling panels) 2 with a circular lid main body 1, and a branch header 4 is provided between ring headers 3 </ b> A and 3 </ b> B disposed on an outer peripheral portion and an inner peripheral portion, respectively. It is connected to the upper surface of the water pipe panel 2 in the radial direction. Each of the water pipe panels 2 is formed by connecting water pipes 2a which are detoured to form a cooling water circulation passage, and are connected to the water pipes 2a of each water pipe panel 2 from the branch header 4 via a water supply pipe and a drain pipe (not shown). Connected to supply and discharge cooling water. These water pipe panels 2
Is a water supply port 2 formed at a predetermined position as shown in FIG.
b, the cooling water is supplied to the water pipe 2a and circulated around the cooling water passage of the water pipe 2a.
drained from c.

At the center of the lid body 1, an electrode block 6 made of a refractory material is disposed via an inner ring 5 made of a ring-shaped circular water pipe 5a. The electrode block 6 has a plurality of (three in the figure) electrode insertion ports 6a.
Are formed, and the electrodes 7 are inserted and arranged in these electrode insertion ports 6a. Further, a dust collection duct 10 having a dust collection port ring 9 composed of a ring-shaped water pipe 9a at the opening is connected to a dust collection port 8 formed at one end of the lid body 1. Water pipes (not shown) and drain pipes (not shown) are also connected to the water pipes 5a and 9a of the inner ring 5 and the dust collection port ring 9.

The water pipe panel 2 and the dust collection port ring 9
As shown in FIGS. 3 and 5, studs 11 having a predetermined thickness and length are implanted at a constant pitch on the inner surfaces of the water pipes 2a and 9a. The diameter of the water pipes 2a, 9a is, for example, 7
In the case of 0 mm, the studs 11 are formed with a diameter of 10 mm and a length of 25 mm, and are implanted at a predetermined pitch d separated by θ = 30 to 60 °. These studs 11 assist in forming a slag layer by attaching and depositing slag scattered by spitting in the scouring reaction,
The deposited slag layer insulates the radiant heat of the molten metal, prevents direct contact of dust accompanying the gas flow, and extends the life of the furnace lid.

The thermal spraying layer according to the present invention comprises first to third thermal spraying layers A to C. The first layer A is a metal-based material having excellent heat resistance and abrasion resistance, and has a thermal expansion with the second layer B. This is a cermet sprayed layer that reduces the difference and realizes reliable adhesion. For example, an Fe—Cr-based cermet or an Fe—Mo-based cermet is used as a spray material. Further, the second sprayed layer B is stable against heat,
Heat resistance and corrosion resistance is formed by a high zirconia ceramic thermal sprayed layer, for example, ZrO ₂ as a spray material
-Y ₂ O ₃ is used. Further, the third sprayed layer C is provided with an electrode 7
Aluminum oxide sprayed layer with high insulation so as not to cause sparks between the tube and the water pipe.
l ₂ O ₃ is used.

The first sprayed layer A and the second sprayed layer B are
Thermal spraying is performed on the entire inner surface of the water pipe panel 2, the inner surface of the inner ring 5, the inner surface of the dust collection ring 9, or the inner surfaces of the dust collection ring 9 and the dust collection duct 10. In the third sprayed layer C, the third sprayed layer C is spray-formed only on a plurality of (two in the figure) water tubes 2a close to the electrodes in the water tube panel 2 on the outer peripheral portion of the inner ring 5. These thermal spray layers A to C
For example, the diameter of the water pipe 2a is 70 mm and the thickness is 8.0 mm.
, The first sprayed layer has a thickness of about 0.5 mm, the second sprayed layer has a thickness of about 0.2 mm, and the third sprayed layer has a thickness of about 0.3 m.
m. Of course, each of the studs 11 is also thermally sprayed, and the heat resistance, corrosion resistance, and wear resistance of the stud 11 are improved.

According to the above embodiment, the water pipes 2a, 5
a, the first sprayed layer A and the second
The thermal spray layer B improves high heat resistance, corrosion resistance, and high abrasion resistance against high-temperature radiant heat due to the scouring reaction and a gas flow accompanied with dust, so that the life can be extended as compared with the related art. Further, a cermet sprayed layer, which is the first sprayed layer A, is formed on the entire inner surface of the metal water pipe panel 2, the inner surface of the inner ring 5, the inner surface of the dust collection ring 9, or the inner surfaces of the dust collection ring 9 and the dust collection duct 10. The zirconia-based ceramic sprayed layer, which is the second sprayed layer B, is formed through the ceramic and metal (water tube).
The cermet sprayed layer reduces the difference in thermal expansion with the cermet sprayed layer, so that the zirconia-based ceramic sprayed layer having high heat resistance and high corrosion resistance can be satisfactorily adhered to metal members such as the water pipe panels 2a, 5a, 9a. In particular, the ceramic (aluminum oxide) of the third sprayed layer C has a small elongation (no toughness), and the role of the second sprayed layer B has a large effect of adhering a metal member well (a thermal barrier coating as a characteristic of the zirconia coating). Excellent.) In addition, since the first and second sprayed layers A and B are also formed on the stud 11, the durability of the stud 11 can be enhanced, and the slag layer can be adhered well, thereby contributing to a longer life.

Further, since the sprayed aluminum oxide layer, which is the third sprayed layer C, is formed on the water pipe of the water pipe panel 2 near the electrode 7, damage due to sparks between the electrode 7 and the water pipe 2a can be reduced, and the life is extended. Can contribute to In the above embodiment, the furnace lid having the tube-to-tube type water tube panel 2 has been described. However, a water-cooled jacket type or a membrane type may be used.

[0015]

As described above, according to the first aspect of the present invention, the inner surface of the water-cooled panel exposed to the radiant heat of the high-temperature molten metal by the scouring reaction and brought into contact with the gas flow accompanied by the dust is formed on the inner surface of the water-cooled panel. Since the second sprayed layer made of a heat-resistant and corrosion-resistant ceramic material is formed via the first sprayed layer, the second sprayed-layer ceramic layer can be stably fixed on the surface of the metal water pipe panel, and the heat resistance and the corrosion resistance In addition, the life can be improved by improving the wear resistance. Furthermore, the third sprayed layer having high insulation and spark resistance can prevent sparks from being generated between the electrode and the water-cooled panel in the vicinity of the electrode, and the third sprayed layer prevents the panel from burning. It can contribute to longer life.

According to the third aspect of the present invention, since the first and second sprayed layers are formed also on the stud, the durability of the stud can be improved, and the slag scattered by the scouring reaction can be reduced. A slag layer is formed by adhering and depositing on the furnace, which can contribute to prolonging the life of the furnace lid.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a furnace lid for an electric furnace according to the present invention.

FIG. 2 is a plan view of the furnace lid.

FIG. 3 is an enlarged view of a portion P shown in FIG.

FIG. 4 is an explanatory view showing a water tube panel of the furnace lid.

FIGS. 5A to 5C show water tubes of the water tube panel;
2A is an enlarged view of a portion Q shown in FIG. 1, FIG. 2B is a cross-sectional view of the water pipe, and FIG. 2C is a side view of the water pipe.

[Explanation of symbols]

 A first thermal spray layer (cermet thermal spray layer) B second thermal spray layer (zirconia ceramic thermal spray layer) C third thermal spray layer (aluminum oxide thermal spray layer) 1 lid body 2 water pipe panel 2a water pipe 5 inner ring 5a water pipe 7 electrode 9 electrode Dust port ring 9a Water pipe 10 Dust collection duct 11 Stud

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F27D 1/12 F27D 1/12 L R 1/14 1/14 Z 1/16 1/16 B 1/18 1/18 A (72) Inventor Katsuhiro Oshio 1-7-89 Minami Kohoku, Suminoe-ku, Osaka City, Osaka Prefecture F-term in Hitachi Zosen Corporation (Reference) 4K031 AA01 AA04 AB03 AB04 AB07 AB08 AB09 CB22 CB23 CB42 CB43 4K045 AA04 BA02 RA09 RA16 4K051 AA05 AB01 CA01 GA05 HA09 KA03 LA03 LA04 LA05 LA11 MA01 MA05 MA08

Claims (3)

[Claims] 1. A second thermal spray layer made of a heat-resistant and corrosion-resistant ceramic material is formed on at least an inner surface of a water-cooled panel in which a cooling water passage is formed in a lid body, via a first thermal spray layer that absorbs thermal expansion. A furnace cover for an electric furnace, wherein a spark-resistant third sprayed layer is formed on the second sprayed layer on the inner surface of the water-cooled panel near the electrode. 2. The thermal spray coating according to claim 1, wherein the first thermal spray layer is a cermet thermal spray layer, the second thermal spray layer is a zirconia ceramic thermal spray layer, and the third thermal spray layer is an aluminum oxide thermal spray layer. The furnace lid for an electric furnace according to the above. 3. A large number of studs are provided on the inner surface of the water-cooled panel to assist the formation of a slag layer, and the second sprayed layer is formed on the surface of the stud via the first sprayed layer. The furnace lid for an electric furnace according to claim 1 or 2, wherein: