JPH02160148A - Heater device - Google Patents

Abstract

PURPOSE:To restrain local heat generation and to improve uniform of heat generation of an exothermic body by inserting electric conductive layer into boundary part between the exothermic body and an electrode part or at between the layers of the exothermic body. CONSTITUTION:After spreading carbon powder as spacer in inner face near bottom of a sintered outer layer part 20, an inner layer part 25 is inserted into the outer layer part 20, and both layer parts 20, 25 are mutually piled. Further, at the boundary part between the outer layer part 20 and the inner layer part 25, the carbon powder is charged from the upper end thereof and the fine gap between both parts 20, 25 is packed with the carbon powder, and by this method, the electric conductive exothermic layer 20a is formed as the electric conductive layer. The electrode part 3 is inserted into hole divided with the inner circumferential face in the inner layer part 25. As the same way, into the boundary part between the electrode part 3 and the inner layer part 25, too, the carbon powder is charged to form the electric conductive exothermic layer 20b as the electric conductive layer. By this method, the local heat generation of the exothermic body 2 is restrained and the uniform heat generation of the exothermic body 2 is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application J] The present invention relates to a heater device. This heater device can be used, for example, when being immersed in molten metal to heat the molten metal.

[Prior Art] A conventionally used heater device will be explained by taking a continuous casting method as an example. Immediately, in the continuous Vt casting method, molten steel at a temperature of, for example, 1400 to 1600°C is first received from a ladle into a tamp push, and the molten metal is poured into a water-cooled mold from the discharge port of the tamp push, where it is cooled and solidified by 1 Jl. After cooling in the cold spray zone, the cooled 1 Jl solidified portion is pulled with a vinyl roll and cut into predetermined lengths, thereby manufacturing slabs, billets, etc. In the continuous casting method described above, the quality of the steel products manufactured is improved compared to the blooming method, and the yield is also improved. However, in recent years, there has been a demand for ever-higher quality steel products, and therefore continuous casting methods are being actively developed to improve the quality of steel products.

In the continuous casting method described above, the temperature of the molten steel tends to drop in the tamp push because the molten steel is primarily received in the tump push. Particularly during continuous casting, at the end of casting, for example, 50 to 80 minutes have elapsed since the start of casting, the temperature of the molten metal drops by several to several tens of degrees Celsius, or even more in some cases. Here, since the tump push is the final container just before the molten metal solidifies, the degree of molten lagoon in the tamp push is the surface inclusion index of the steel product, the central segregation of carbon 1
It has a great influence on the h number, and therefore has a great influence on improving the quality of steel products. Therefore, even if the molten metal in the tank push drops by several tens of degrees Celsius, the quality remains the same! ! Logically undesirable.

Therefore, in recent years, in order to adjust the temperature of the molten steel in the tampush, a carbon electrode is immersed in the molten metal in the tampush, and a current is passed directly through the molten metal itself. A heater device that generates heat by itself is provided.

However, in this case, the electrical resistivity of the molten metal is small. Here, since the Joule heat generated by the molten metal is the product of the electrical resistance value of the molten metal and the square of the current value flowing through the molten metal, as mentioned above, if the electrical resistivity of the molten metal is small, the required Joule heat is In order to secure heat, there is a problem in that a considerably large amount of current is required to be passed through the molten metal, and there is also a problem in that the electric equipment becomes large in size due to the large current.

In addition, as other heater v devices that heat the molten metal in the tongue push, conventionally, the molten metal in the tongue push is
! Induction heating devices have also been provided that provide conductive heating. Furthermore, a plasma heating device is also provided in which a plasma torch is installed above the tongue pusher to plasma-heat the molten metal inside the tongue pusher.

[Disadvantage to be Solved by the Invention] As a result of extensive research in order to reduce the mvl flowing through the molten metal, the inventor has discovered that the present inventor has developed a heater device consisting of a heating element and an electrode section, and has We have developed a method for heating the molten metal by immersing the molten metal into the molten metal and applying a voltage between the heater device and the molten metal to cause the heating element of the heater device to generate heat.

The present invention was completed as part of the development of the above-mentioned heater device, and its purpose is to heat an object to be heated, such as molten metal, by generating heat from a heating element, and furthermore, to It is an object of the present invention to provide a heater device which is advantageous in ensuring the heat generating property of the heating element by interposing a conductive layer at the boundary between the heating element and the layer forming the heating element.

Furthermore, it is an object of the present invention to provide a heater device which is more advantageous in ensuring the heat generating property of the heating element when the conductive layer has heat generating property.

- 2 [Means for Solving Problem W1] The heater device according to the present invention includes a heating element made of at least 111 and whose heat generating material is ll material, and an electrode section that is placed adjacent to the heating element and conducts electricity to the heating element. It is characterized in that a conductive layer is interposed at the boundary between the heating element and the electrode portion or between the layers of the heating element.

The heating element is formed from at least one layer using a heat-generating material as a base material. The heating element can be composed of an outer layer portion having a required heat generation characteristic and at least one inner layer portion having a heat generation characteristic different from that of the outer layer portion.

Here, the expression "based on a heat-generating material" means that the base material may be formed only of a heat-generating material or may contain a filler other than the heat-generating material. The inner layer is 1 if necessary.
It may be a layer or two layers, and depending on the case, it may be more than two layers. The thickness of the heating element may be substantially uniform in order to ensure uniformity of heat generation, but depending on the type of heat generating material, there may be a portion with varying thickness.

The heating element can have a cylindrical shape or a shape similar to a cylindrical shape, and in this form it can be used as a type that is crushed into molten metal. In this case, the heating element is formed of an outer layer part and an inner layer part. In some cases, both the outer layer portion and the inner layer portion may have a cylindrical shape or a shape similar to a cylindrical shape. Here, when the heating element is formed into a cylinder shape or a shape similar to a cylinder shape, the outer diameter of the central part of the heating element in the longitudinal direction is substantially It is desirable to make the thickness of the central part of the heating element substantially uniform in the longitudinal direction by making the inner diameter of the central part substantially the same in the longitudinal direction. In this case, the relationship between the outer diameter and the inner diameter of the central portion in the longitudinal direction of the heating element is such that the inner diameter can be 30 to 80% of the outer diameter, and preferably 50 to 70%. The reason for this is that if the ratio of the inner diameter to the outer diameter is small, the amount of heat generated in the inner diameter portion will be greater than that in the outer diameter portion, and as a result, there is a risk that the inner diameter portion will melt. Further, as the inner diameter ratio increases, the substantial thickness of the heat generating layer decreases, making it more susceptible to melting loss due to melting.

In the heater device according to the present invention, the heat generating material forming the heating element may be either non-metallic or metallic. When a heating element is formed of an outer layer and an inner layer, the type of heat-generating material forming the outer layer or its blending ratio has a higher electrical resistance value than the type or blending ratio of the heat-generating material forming the inner layer. It is possible to adopt high quality products. In this way, heat generation will increase in the area close to the object to be heated (for example, liquid such as molten metal, gas such as air) that contacts or faces the outer layer of the heating element, and It is advantageous for effectively heating the object and increasing the heating efficiency.

In addition, in the heater device according to the present invention, since the outer layer normally comes into contact with molten metal, air, burner flame during preheating, etc., the type of heat-generating material forming the outer layer or the blending ratio C thereof has different heat-generating properties. In addition, it is necessary to consider various factors such as erosion resistance, thermal shock resistance, oxidation resistance, corrosion resistance, aging resistance, etc., when selecting the inner layer. Therefore, such consideration can be reduced or ignored when selecting the type of heat-generating material forming the inner layer or its blending ratio. The material may have a lower specific resistance value and less heat generation than the heat generation material forming the outer layer portion, and may have a mixing ratio. Therefore, the degree of freedom in selecting the type of heat generating material forming the inner layer portion or its blending ratio is increased compared to the type of heat generating material forming the outer layer portion or its blending ratio.

In the heater device according to the present invention, the above-mentioned metal scrap-based heat-generating material forming the heating element includes, for example, a nickel-chromium alloy, an iron-O2-aluminum alloy, tungsten, molybdenum, tantalum, etc. Can be adopted accordingly.

Further, as the above-mentioned non-metallic heating material forming the heating element, ceramics having conductivity in the operating temperature range among oxide-based, nitride-based, boride-based, etc. can be used. I.J.
Ceramics with I properties include [, 1. When the object to be heated is molten steel, the resistance of the molten steel is low, so it is necessary to increase the R of the heating element. is desirable; in this case, the specific resistance value is 150
At around 0°C, it is preferably 1 Ωcm or more, especially 2000CrT1 or more, for example,
A material having a specific resistance value of about 360 (Ωcm) can be used. Note that the specific resistance value of the heating element can be changed by blending non-conductive ceramics or poorly conductive ceramics with conductive ceramics and adjusting the blending ratio.

In the heater device according to the present invention, when heating molten steel, magnesia (MgO) and Zirninia (Zr
Ot), aluminum (A1tO3), a mixture of magnesia and zirconia, and a mixture of magnesia, zirconia and alumina can be used. Here, magnesia does not normally have electrical conductivity near normal temperature, but it takes on the required electrical conductivity near 1500 to 1650° C., which is the heating range of molten steel [1]. When the heating element is formed of an outer layer part and an inner layer part, a mixture of magnesia and zirconia can be used as the electrically conductive ceramic forming the outer layer part, and in this case, the blending ratio teeth,
It is selected appropriately considering the required resistance value, etc., but for example, magnesia is 60 to 100% by weight, especially 85 to 100%.
95% is preferred, zirconia 0-40% especially 5-2
5% is preferred, alumina 0-40% especially 2.5-1
5% is preferable, and the conductive ceramics forming the inner layer include, for example, zirconium boride,
Boron nitride, silicon carbide, etc. can be used as necessary. The conductive ceramics forming the inner layer include magnesia (MgO), zirconia (2RO2), alumina (A12203), a mixture of magnesia and zirconia, magnesia, zirconia and alumina, as well as the outer layer. However, the blending ratio can be changed to reduce the heat generation m4 compared to the outer layer, for example, by reducing magnesia to fffffl%, magnesia 40 to 70%, zirconia, alumina, C
One or more materials containing ao1 chromia, beryllia, doria, and ceria as main components can be blended in an amount of 30 to 60% or more.

Furthermore, if necessary, for example, in order to reduce the calorific value compared to the outer layer, carbon powder, graphite, etc. may be used to reduce the amount of carbon from 1 to
It can also be contained as appropriate at 5%.

Furthermore, depending on the melting point of the molten metal, silicon carbide (S) may be used as a conductive ceramic to form the heating element.
iC), lanthanum chromate (LaCrOi)
, beryllium oxide (BeO), thorium oxide (That
＞, molybdenum silicide (MoS12), titanium nitride (TiN＞, titanium carbide (T i C), etc.6) can be used.For reference, the relationship between operating temperature and specific resistance can be used. are shown in Figures 8 and 9.In the case of molten steel, as mentioned above, the specific resistance value of the ceramic that forms the heating element is set as a target value, especially when forming the outer layer. is 2 in the operating temperature range.
00 Ωcm or more is desirable.

However, among the various heat-generating materials mentioned above, the heating temperature of the object to be heated such as molten metal, the acidic or reducing atmosphere of the place where the heater device is used, the heat resistance of the heat-generating material, and the i! ! It should be selected appropriately, taking into consideration impact resistance at temperature I, price, and whether or not it is toxic.

In addition, when the heating element has zirconia as a main component, calcium oxide (Cab), magnesia (MgO), yttrium oxide (YtO3), ytterbium oxide (Yb
tOs>, stabilized zirconia with scandium oxide (SCtOx> added in an amount of several percent to several tens of percent to avoid transition,
Metastable zirconia can be used. In this way, expansion caused by the transition can be avoided, which is advantageous in suppressing distortion of the photothermal body.

When the heat generating material is conductive ceramics, the particle size of the conductive ceramics may affect the resistance value, so it is desirable that the maximum particle size is about 1 to 5 mm.
In particular, about 1.5 to 3 mm is desirable. The main reason for this is that if the particle size is too large, the current tends to become uneven. In addition, when the heating element is formed of an outer layer part and an inner layer part, the particle size of the outer layer part and the inner layer part can be changed to adjust the heat generation characteristics of the outer layer part and the inner layer part, for example,
In order to suppress "heat accumulation" inside the heating element, it is also possible to make the heat generation property of the inner layer part smaller than that of the outer layer part.

In the heater device according to the present invention, the resistance value of the heat generating material forming the heat generating element does not change even if the operating temperature changes, unless there are other problems, or 2) the resistance value increases. It is possible to use a method that shows the correctness of the test. In this case, when the resistance value of the heat-generating material increases as the temperature rises, when a high-temperature part is generated in the heat-generating element, the resistance value of the high-temperature part becomes high. Therefore, the current flows through the portions where the temperature is lower than the high temperature portion, which is convenient for uniformly generating heat throughout the heating element. If the heat-generating material has a large negative resistance value that decreases significantly when the temperature rises, if a high-temperature portion is formed in the heat-generating element, the resistance value of the high-temperature portion will decrease. Therefore, the current flows more easily in the parts with a lower temperature than the high temperature parts, and the current flows more easily in the high temperature parts with low resistance.Therefore, the high temperature parts become more and more high 4, which is one of the causes of runaway heat generation of the heating element. It's easy to become.

The total resistance R (Ω) of the heating element is determined by the specific resistance value ρ (Ωcm) of the heating material such as conductive ceramics and the thickness of the heating element 19t (
Cm) and the area S (cm2) of the heating element. At this time, when the heating element is made into a cylindrical shape, it is necessary to select the resistance value of the heating element in consideration of the following matters. In other words, the larger the outer diameter of the heating element, the more heat radiation area can be secured.
Cracks occur easily during molding and are susceptible to thermal shock. On the other hand, the smaller the outer diameter of the heating element, the smaller the heat radiation area.

Also, the larger the inner diameter of the heating element, the larger the diameter of the electrode part.
Heat transfer loss from the electrode part is large. On the other hand, the smaller the inner diameter of the heating element, the smaller the diameter of the electrode portion, and the smaller the heat transfer loss from the electrode portion, but the more uneven heat generation tends to occur. Further, the thicker the heating element, the more likely heat will accumulate inside the heating element, and the maximum temperature inside the heating element may rise and the inside may melt, which is disadvantageous in maintaining the stability of heat generation. On the other hand, the thinner the heat generating element is, the more difficult it is for heat to accumulate inside the heating element, but the necessary heat generating layer cannot be obtained, and this tends to be a cause of runaway heat generation.

In the heater device according to the present invention, the heating element can be manufactured, for example, as follows. That is, after the raw ceramic powder is sufficiently ground and mixed using a ball mill, vibration mill, etc. to adjust the composition to a predetermined composition, a slurry of the raw ceramic powder and water is poured into the kisebite of a mold and molded into a predetermined shape. A molding process is carried out to obtain a body, and a sintering process is further carried out in which the body is heated to a predetermined temperature and sintered. Prior to the sintering process, a curing process and a drying process are performed if necessary.

In the molding process, vibration molding can be performed in which molding is performed while applying vibration to the mold. Then, the heating element and the electrode section are assembled into one piece.

Moreover, the heating element can also be manufactured in the following manner.

That is, the raw material ceramic powder is thoroughly ground and mixed using a ball mill, @dynamic mill, etc. to prepare the raw material Hiramix powder. Then, the raw ceramic powder is pressure-molded to form a compacted body. Thereafter, a drying step is performed if necessary, and the material is heated to a high temperature and sintered. In addition, pressure molding is
Known means such as a press method, an isostatic pressure method, a hot press method, etc. can be employed. The heating element and the electrode part are assembled into one body using the sled.

Now, the main structure of the heater device according to the present invention will be explained. That is, the conductive layer is interposed at the boundary between the heating element and the electrode portion, or between the layers when the heating element is formed of two or more layers. The conductive layer can be formed at the boundary between the heating element and the electrode part, or in the open air when the heating element is formed of 218 or more, with conductive powder, liquid, etc. interposed therebetween. In this case, current diffusion i of powder, granular material, liquid, etc.
By utilizing this function, it is possible to improve the degree of electrical contact at the boundary between the heating element and the i1i pole part, or the degree of electrical contact between the layers when the heating element is formed of two or more layers. In this case, even if a gap is likely to occur at the boundary between the heating element and the electrode part, or even if the heating element is 21! ! When formed in the above manner, even if gaps are likely to occur between the layers, it is advantageous in ensuring electrical contact and even thermal contact between the two images. Alternatively, if the degree of thermal expansion of the heating element and the ffl pole part is different, or if the heating element is formed of two or more layers, even if the degree of thermal expansion between the layers is different, the electrical It is advantageous to ensure thermal contact in the physical contact history. In addition, when forming the conductive N layer using powder or granule, the powder or granule may include conductive powder with photothermal properties,
For example, carbon powder or graphite powder can be used, or ceramic powder such as silicon carbide powder, or metal powder with a high melting point and high resistivity value can be used in some cases, and the above powders can be mixed as necessary. It can be used as Note that the relationship between the specific resistance value of carbon powder or graphite powder and the operating temperature range is such that even if the operating temperature range becomes high, the decrease in the specific resistance value can be minimized, which is advantageous in ensuring heat generation in the high temperature range. In addition, when forming the conductive NH with a liquid,
As the liquid, one that is immersed in 1j conductivity and has a low melting point, such as a low melting point metal such as tin, lead, bismuth, or sodium, or in some cases, a copper metal, an aluminum metal, etc. can be used.

When the conductive f11111 is formed from a conductive powder such as carbon powder or graphite powder, from the viewpoint of ensuring the heat generation property of the conductive layer itself, a fine particle size is preferable, and the average particle size range is, for example, 10μ. ~2 mm, and can be set to 50 μ to 100 μ. This is because it is thought that the finer the particle size, the greater the contact resistance between the powder particles, ensuring the heat generation properties of the conductive layer.

In addition, the solid powder made of low melting point metal or copper-based metal, etc. should be placed at the boundary between the heating element and one pole part, or when the heating element
If it is formed of more than one layer, if it is interposed between 111 and 111, if the temperature during use is above the melting point, the solid powder will melt and become liquid, which will improve the electrical contact and thermal properties. This is advantageous in ensuring good contact.

In the heater device according to the present invention, as exemplified in the embodiments described later, the longitudinal tip of the heating element has a three-dimensional curved shape, such as a hemispherical shape or a shape approximating a hemispherical shape, so that there are no corners. It is desirable that The reason for this is that corners tend to be uneven during molding (and it is difficult to ensure thermal shock resistance).

Further, since it is difficult for the current to concentrate at the corners, the heat generation temperature at the corners increases, which is likely to be one of the causes of runaway heat generation. In addition, when the tip part is hemispherical, the radius of the hemispherical tip part of the heating element is, for example, 30 to 100 mm, especially 40 to 60 mm, in the type that is immersed in the molten metal in the tundish.
It can be about rT1.

In the heater holder according to the present invention, the electrode portion is for passing electricity through the heating element, and is provided adjacent to the heating element.

The material of the electrode part is selected in consideration of electrical conductivity, heat transfer coefficient, etc. In this case, the conductivity can be increased and the heat transfer coefficient can be decreased to reduce heat transfer loss. However, in general, as the conductivity of a substance increases, the heat transfer rate also tends to increase, so it is better to use three materials than to form an electrode part with a single material.
4 By appropriately combining materials with high electrical conductivity and materials with low heat transfer coefficient, l! While ensuring the required conductivity of the electrode part, the apparent degree of heat transfer in the 'R electrode part can be reduced.

Further, the electrode portion can also be formed of a conductive ceramic having low electrical resistance.

In the heater device according to the present invention, it is desirable that the electrode portion be thinner in order to reduce heat transfer loss from the pole portion.

In addition, when the heater device according to the present invention is used to heat molten metal held in a container, a sensor 1t such as a gamma ray level meter for detecting the molten metal storage opening is provided, and a sensor 1t is installed to detect the sensor signal. The current to the heating element according to i
It is also possible to provide an i-control device that performs llH. In this way, the amount of current flowing to the heating element is controlled according to the amount of variation in the molten metal held in the container, so the temperature of the molten metal can be adjusted with even greater accuracy.

[Example] A first example of the heater device according to the present invention will be described with reference to FIGS. 1 and 2.

A heater device [1 according to this embodiment is shown in FIGS. 1 and 2. This heater device [1 is an almost flask-shaped heating element 2]
and a rod-shaped electrode portion 3 adjacent to the heating element 2. The heating element 2 is of a two-layer type, and is formed of an outer layer part 20 in the shape of a hollow flask and an inner layer part 25 in the shape of a hollow flask.

The outer layer portion 20 is formed of a mixed ceramic containing unavoidable impurities such as 90% magnesia, 5% zirconia, and 5% alumina by weight. The inner layer part 25 is
In weight%, magnesia is 60%, zirconia is 40%,
It is made of mixed ceramics that contain unavoidable impurities.

As shown in FIGS. 1 and 2, the outer layer portion 20 includes a large-diameter proximal end portion 200, a central portion 210 connected to the proximal end portion 200, and a three-dimensional curved surface shape, that is, a hemispherical tip connected to the central portion 210. 220. The thickness of the central portion 210 and the thickness of the tip portion 220 are substantially uniform, and the variation in thickness is ±1 mm and 1 degree. Here, in this embodiment, the entire length Ll in the axial direction of the outer layer portion 20 is approximately 85 cm, the length L2 of the central portion 210 is approximately 55 cm, and the tip portion 22 is approximately 85 cm.
0 length L3 is approximately 6 cm, and the outer diameter of the central portion 210 is 12 cm.
cm1! j degree, the inner diameter of the central part 210 is about 8°4 cm,
The diameter R1 of the tip portion 220 is approximately 5 cm. Note that the reason why the base end portion 200 has a large diameter is to place it on a heater holder.

On the other hand, the inner WJ/11!25 has a proximal end 250, a proximal end 250, a three-dimensional curved surface shape, that is, a substantially hemispherical distal end 270 connected to the central part 260. It consists of Inner layer part 25
The wall Jf is substantially uniform, and the variation in wall thickness is ±1
It is about mm. Here, in this embodiment, the outer diameter of the center portion 260 of the inner layer portion 25 is approximately 3 cm;
The inner diameter of the tip portion 270 is approximately 4 cm, and the diameter R2 of the tip portion 270 is approximately 4 cm.

The pole part 3 of the rod-like 71 is made of carbon, and its outer diameter is 3
．． The length is about 8cm, and the total length is about 85cm.

The heater device of this example was manufactured as follows.

That is, after adjusting the raw material ceramic powder for the outer layer part 20 at a predetermined blending ratio, water is added to form a slurry; a molding process of pouring the slurry into a mold cavity and molding; and a molded outer layer part 20. After removing the molded body from the mold, the molded body is cured and further dried at 150°C for 15 hours.
A sintering process of heating for 0 hours and sintering was performed in order. Note that the maximum particle size of the raw ceramic powder for the outer layer portion 20 used in the adjustment process is about 3 mm. A mold for the inner layer portion 25 was formed using the same procedure to form the inner layer portion 25. The maximum particle size of the raw ceramic powder for the inner layer portion 25 is about 3 mm. Then, after scattering carbon powder with a maximum particle size of about 1.5 mm as a spacer on the inner surface near the bottom of the sintered outer layer 20, the inner layer 25 is inserted into the outer layer 20, and the outer layer 20 and the inner layer are separated. 25 on top of each other.

Further, carbon powder is charged into the boundary between the outer layer part 20 and the inner layer part 25 from the upper end, so that the fine 11! The space between the two is filled with carbon powder, thereby forming a conductive heating layer 20a as a conductive layer.

At this time, if necessary, the inner layer part 25 and the outer layer part 20 can be rotated relative to each other in the circumferential direction.

This is because it is easy to charge carbon powder. At this time, since the carbon powder is rich in lubricity, the relative rotational movement is performed smoothly.

Note that the m-pole portion 3 is inserted into a hole defined by the inner circumferential surface of the inner layer portion 25. Similarly, carbon powder is similarly charged to the boundary between the electrode part 3 and the inner layer part 25 to form the IJN heat generating layer 2-Ob as IFffill.

When using the heater device 1 manufactured as described above, for example, two heater devices 1 are used, and a conductive wire is fixed to the upper end of the rod-shaped electrode portion 3 of each heater device 1 with a band.
2I! Connect it to the power source and apply the burner flame to 1 heating element 2 to preheat it. After preheating, the two heater devices 1 were immersed in the molten steel W in the container 4, as shown in FIG. In this state, a voltage of 0 to 440V (7) is applied between the electrode part 3 of 211JJ and the molten metal W, and a frequency of 60V is applied.
Flow an HZ current of about 0 to 800 A. Then, the inner layer part 25 and the outer layer part 20 forming the heating element 2 of one heater device 1 generate heat, and the heating element 2 of the other heater device M1 generates heat.
Since the inner layer portion 25 and outer layer portion 20 forming the molten metal W are heated, the molten metal W is heated.

In this embodiment, in order to heat the molten metal using the calorific value of the heating element 2 of the heater device 1, it is possible to heat the molten metal using the Joule heat generated in the molten metal itself by directly passing an electric current through the molten metal itself, which is conventionally provided. In comparison, the amount of current required is small, so it is easy to electrically control it, and the electrical equipment can be downsized.

In this embodiment, the outer layer part 20 is formed of a heat-generating material whose main components are magnesia and zirconia and whose compounding formula is 11 to increase the resistance value, so that the part in contact with the molten metal W generates heat. increases, and heating efficiency improves.

Moreover, since the inner layer part 25 does not come into contact with the molten metal, the heat generating property of the outer layer part 2o is not required. In addition, when preheating with a burner, the inner layer portion 25 does not come into direct contact with the flame of the burner. There is no need to ensure a large amount of heat generation, and there is no need to pay great attention to corrosion resistance, oxidation resistance, etc., and therefore there is freedom in selecting the type of heat generating material forming the inner layer portion 25 and the proportion thereof. It can increase in degree.

Furthermore, in this embodiment, when the thickness of the heating element 2 is set to the required thickness in order to secure the required heating openings, the thickness of the outer layer 20 and the inner layer 25 can be made thinner. Accordingly, cracks are less likely to occur in the outer layer portion 20 and the inner layer portion 25 themselves during molding, sintering, and preheating.

Moreover, in this embodiment, as shown in FIG. The conductive heat generating layer 11120a made of carbon powder and the conductive heat generating layer 1!20b made of carbon powder charged at the boundary between the inner layer part 25 and the rod-shaped electrode part 3 function as a current diffusion layer and R as a heat diffusion layer. As a result, the degree of electrical contact between the outer IMl'1lS20 and the inner layer part 25 is increased, and the degree of thermal contact is also increased, suppressing the local heat generation of the heating element 2, and therefore, the heating element 2 is able to reduce heat generation. As a result, the heating element 2 has the advantage of uniform heat generation.

Furthermore, in this embodiment, the conductive heat generating layers 20a1 and 1!20b formed by charging carbon powder also generate heat during use. Moreover, the specific resistance value of carbon powder decreases even if the operating temperature range becomes high! Since it is smaller than that of 74-carbon ceramics, it is advantageous in securing heat generation in a high temperature range. Therefore, in order to ensure the required calorific value of the heating element 2, it is possible to avoid excessively increasing the thickness of the outer layer portion 20 and the inner layer portion 25, and therefore, the thickness of the heating element 2 due to the increase in thickness can be avoided. It is possible to suppress "heat accumulation" inside the 2, and further "ceramic melting" caused by the "heat accumulation". Moreover, since the conductive heat generators 1120a and 20b made of carbon powder do not come into contact with the molten metal, the carbon powder does not enter the molten metal, and m
It does not interfere with the carbon retention of the lagoon.

Furthermore, in this embodiment, since the thickness of the outer layer 20 and the inner layer 25 forming the heating element 2 are substantially uniform, the current flowing from the electrode part 3 through the heating element 2 to the It is effective in preventing unbalanced flow.

Further, in this embodiment, the tip 220 of the outer layer 20 and the tip 270 of the inner layer 25 forming the heating element 2 each have a hemispherical three-dimensional curved shape, and 1! Since there are no corners where current tends to concentrate, it is more advantageous in preventing uneven current flow.

Next, a second embodiment of the heater v4 according to the present invention will be described with reference to FIGS. 5 and 6.

The heater device of the second embodiment basically has the same configuration as the first embodiment. However, the inner layer part is two layers, and as shown in FIG. 5, the first inner layer part 27 and the second inner layer part 28 on the rod-shaped electrode part 3 side are laminated.

The first inner layer section 27 is formed of a proximal end 270, an intermediate section 271, and a substantially hemispherical distal end 272. Further, the second inner portion 1laIS 28 is formed of a proximal end portion 280, an intermediate portion 281, and a substantially hemispherical distal end portion 282. Carbon powder is charged between the first inner layer 27 and the second inner layer 28 to form a conductive heating element 1i120a. Part 2
The degree of electrical contact and thermal contact with 8 is ensured.

Of course, a conductive heating layer 20a made of carbon powder is provided at the boundary between the outer layer section 20 and the second inner layer section 28, and a conductive heating layer 20a made of carbon powder is provided at the boundary between the N-pole section 3 and the first inner layer section 27. A conductive heat generator 1120b made of carbon powder is also provided.

In the heater device of the second embodiment, the same functions and effects as in the first practical example can be obtained.

Furthermore, in each of the embodiments described above, as is clear from FIGS. 1 and 5, the outer circumferential surface of the inner layer portion and the inner circumferential surface of the outer layer portion are flat WI.
Although it is planar, in a special case (not shown), a threaded part is formed on the outer peripheral surface of the inner layer part, a threaded part is formed on the inner peripheral surface of the outer layer part, and the threaded part of the outer layer part and the inner layer are formed. The inner layer and outer layer can be integrally assembled by screwing together the threaded portions of the parts, and in this case as well, carbon powder, molten tin, etc. may be charged into the boundary between the two. , a conductor 11fil can be provided.

- [Application example] Next, an example in which the heater device according to the above embodiment is applied to a continuous casting method will be described. First, a continuous casting apparatus used in the continuous casting method will be explained. As shown in FIG. 7, this continuous casting apparatus includes a tongue pusher 50 as a container for holding molten steel, a water-cooled mold 51 disposed below the tongue pusher 50, a cooling spray zone 52, and a pinch roll. 53 and a straightening roll 54. In addition, the tongue push 50 handles the molten metal at 5tP.
It is the capacity to hold 1 degree.

Next, continuous casting will be explained. First, using two heater devices 1 shown in FIG. 1 and FIG.
Preheat to around 00℃.

With the heater device 21 preheated in this way, the ladle 5
14 transferred from 5 and retained in tundish 50
Two heater devices 1 are immersed from their tips 220 into molten steel at a high temperature of about 00 to 1600°C. The molten metal in the tundish 50 transferred from the ladle is discharged through the discharge port 5 shown in FIG.
It flows toward 0a and falls into the water-cooled mold 51.

If the heater device R1 is preheated before immersing the molten metal as described above, rapid heating of the heating element 2 can be prevented, and generation of electrical equipment on the heating element 2 can be suppressed as much as possible. Moreover, by the above-mentioned preheating, it is possible to ensure the conductivity of the heating element 2, especially the heating element 2, which has N-conductivity (N conductivity) at first in a high temperature region because the main component is magnesia.

Note that if a crack occurs in the heating element 2, the molten metal that has entered the crack will be directly connected to the electrode part 3, and the heat generation ω of the heating element 2 will become small, resulting in the inconvenience that the heater assembly W11 cannot be used effectively. arise.

In this application example, with the heater device 1 immersed in the molten metal in the tongue pusher 50 as described above, the terminals of the two electrode parts 3 are connected to an AC power source, and a voltage of 100 to 600 μ is applied between the terminals. Apply. As a result, a current with a frequency of 60 Hz is caused to flow between the heating elements 2 of the heater device 1 via the molten metal held in the tongue pusher 50. The current resistance is about 0 to 800A.

At this time, the inner layer portion 25 and outer layer portion 20 of the heating element 2 generate heat to a high temperature. Therefore, the molten metal held in the tundish 50 is heated, for example, about 1 to 1.5 b The molten metal whose temperature has been adjusted in this way in the tundish 50 is discharged from the discharge port 50a of the tundish 50, and is cooled and solidified in the water-cooled mold 51. and further cold rJl spray zone 5
B was cooled by a jet of cold water from 2 and solidified.
is pulled downward by pinch rolls 53. After that, it is cut into a predetermined length by a cutting machine.

In this application example, in order to heat the molten metal in the tundish 50 with the heating cell of the heating element 2 of the heater device ff11, a current is directly applied to the molten metal itself held in the tundish 50, which is conventionally provided. Compared to the case where the molten metal is heated using the Joule heat generated in the process, the amount of R flow required is small, so it is easy to control electrically, and the electrical equipment can be downsized, making it possible to reduce the size of existing electrical equipment. It can be used effectively.

As described above, in this application example, the temperature of the molten metal held in the tongue push 50 can be adjusted by heating the molten metal held in the tongue push 50 with the heater device [1], so that the temperature of the molten metal held in the tongue push 50 can be maintained at an appropriate value. This is advantageous for improving the quality of plumes, billets, and other products manufactured by continuous casting.

[Effects of the Invention] According to the heater device of the present invention, it is possible to heat an object to be heated, such as a molten metal, using a heating element, and therefore it is possible to adjust the temperature of an object to be heated, such as a molten metal. In particular, the boundary between the heating element and the electrode part or the heating layer
In the case of more than one layer, a conductive layer is interposed between the shells, so
This conductive layer functions as an N-flow diffusion layer and also as a heat diffusion layer, so it can increase the degree of electrical contact and also the degree of thermal contact, so local heat generation can be suppressed. Therefore, the heating element is less likely to run out of heat, which is advantageous in improving the uniform photothermal properties of the heating element.

Furthermore, according to the heater device of the present invention, when the conductive layer has heat generating properties, the conductive layer also generates heat in addition to the heat generating element. It is possible to avoid excessively increasing the thickness of the body, and therefore, the "
This is advantageous in suppressing heat buildup.

Furthermore, according to the heater device of the present invention, when the heating element is formed of two or more layers, the inner layer has a higher heat generation characteristic than the outer layer while ensuring the required heat generation property in the outer layer. Since it is made of a heat generating material with a small amount of heat generating material, it is more advantageous in suppressing "heat accumulation" inside the heat generating element.

[Brief explanation of the drawing]

1 to 4 show a first embodiment of the present invention, in which FIG. 1 is a sectional view of a heating element, and FIG. 2 is a sectional view of a heater device. FIG. 3 is an enlarged sectional view of the vicinity of the conductive heating layer, and FIG. 4 is a schematic sectional view of the state in which electricity is being applied between the heater device and the molten metal. 5 and 6 show a second embodiment of the present invention, in which FIG. 5 is a sectional view of a heating element, and FIG. 6 is a sectional view of a heater device. FIG. 7 is a schematic cross-sectional view of an apparatus used in the continuous casting method. FIGS. 8 and 9 are graphs showing the relationship between the operating temperature and specific resistance of a conductive material. In the figure, 1 is a heater device, 2 is a heating element, 3 is a rod-shaped electrode part,
20 is an outer layer part, 20a is conductive heat generation m<conduction? 1tNl),
20b is the heat conducting layer (guiding ffi layer), 200 is the proximal end, 210 is the center, 220 is the distal end, 25 is the inner layer, 250 G;! The base end, 260 is the central part, and 270 is the distal end.

Claims (1)

[Claims] (1) Consisting of a heating element made of at least one layer and made of a heat-generating material as a base material, and an electrode part that is placed adjacent to the heating element and supplies electricity to the heating element, the boundary between the heating element and the electrode part , or a heater device characterized in that a conductive layer is interposed between the layers of the heating element.