JP5804442B2 - Lining drying method - Google Patents

Description

The present invention relates to a method for drying a lining applied to, for example, a molten metal container or a jar.

Conventionally, for example, a refractory is lined on the furnace inner side (molten steel contact surface side) of a molten metal container for iron making. In using this molten metal container, it is necessary to dry the refractory in advance, but there is a problem that the refractory explodes during this drying.
For this reason, the search of the drying method for preventing the explosion of a refractory has been performed conventionally.
On the other hand, for example, Patent Documents 1 and 2 describe examples of efforts to reduce heat dissipated from the iron skin by arranging a heat insulating material between the lined refractory and the iron skin.
Patent Document 3 describes a method of shortening the drying time of the wear refractory by disposing a heat insulating material between the wear refractory and the permanent refractory constituting the lined refractory.

JP 2010-266103 A JP 2010-248563 A Japanese Patent Laid-Open No. 10-206031

However, Patent Documents 1 and 2 are based on the premise that a fixed refractory is used instead of an irregular refractory for the wear refractory and the permanent refractory constituting the lined refractory.
In addition, in Patent Document 1, it is described that an amorphous refractory can be applied as a wear refractory. However, when estimated from the thermal conductivity (15 W / (m · K) or more) of Examples, the amorphous refractory is It is unlikely that you are using it. Patent Document 1 describes a C-containing wear refractory, but since C is hydrophobic, it generally requires a large amount of kneaded water, resulting in a high porosity. Thus, it is difficult to obtain a thermal conductivity of 15 W / (m · K) with an irregular refractory, and it can be seen that this is an example using a regular refractory.
From the above, in Patent Documents 1 and 2, it is considered that C-containing non-fired shaped refractories are used. However, drying of unfired shaped refractories is caused by volatilization caused by the resin responsible for shape retention. The purpose is to remove the minute, and the risk of explosion is small compared to drying before using the amorphous refractory containing water (before pouring the molten metal).

Patent Document 3 describes a moisture removal temperature (in this case, 350 ° C.) on the back surface of the wear refractory as an index for preventing explosion of the wear refractory composed of an irregular refractory. In other words, if the temperature of the wear refractory is raised to this moisture removal temperature (if the absolute value of the temperature is controlled), there is no concern about the explosion of the wear refractory when the temperature rises thereafter. effective.
However, according to the experience of the present inventors, it has been found that the explosion can be suppressed to some extent only by managing the absolute value of the temperature described in Patent Document 3, but there is room for improvement. Moreover, in patent document 3, the crack and peeling at the time of actual use (at the time of actual use) are described as a subject, for example, the explosion by the water evaporation at the time of drying around 100 degreeC is not made into the subject.

In general, for example, when an amorphous refractory is used as a wear refractory for a molten metal container, drying is performed to remove moisture in the amorphous refractory before use (before pouring the molten metal). The drying process for performing the drying is performed after a series of refractory construction work for the molten metal container is completed. In other words, the drying process is the final process before receiving the molten metal, and once an irregular refractory explosive trouble occurs, construction of the irregular refractory (rework or rework after dismantling) is required again. Compared to the case where no trouble occurs, the construction period of the refractory is greatly extended.
For this reason, in some cases, the production opportunity is lost and the influence is great.
Further, when repairing a wear refractory after use of a molten metal container with an irregular refractory, it is necessary to remove moisture in the irregular refractory as described above, and it is necessary to prevent explosion problems.

When constructing the above-mentioned amorphous refractory as a wear refractory, the pouring method (casting material) is generally used. When repairing the used ware refractory with an undried amorphous refractory (repair material) A shot method (shot material), a trowel coating method (trowel coating material), and a spraying method (spraying material) are used. These methods differ in the construction method of providing a layer of amorphous refractory, for example, the amount of water mixed in the amorphous refractory increases in the order of casting material, shot material, trowel material, spraying material, etc. The preconditions for drying are different. That is, even if the same material and the same drying conditions (heating temperature) are used, it means that explosion may easily occur if the construction method is different.
From the above, the absolute value control of the temperature described in Patent Document 3 can obtain a certain effect of preventing explosion, but various irregular shapes constituting the wear refractory and its repair material having different construction methods and preconditions. It turned out to be difficult to prevent further explosion of the entire refractory.

The present invention has been made in view of such circumstances, and prevents explosions as compared with the prior art, specifically, when a water-containing unfired refractory layer formed of a wear refractory or a repair material thereof is dried. It is an object of the present invention to provide a method for drying a lining that can suppress or even prevent explosion in the lining.

The method for drying a lining according to the present invention that meets the above-described object is characterized in that one or more water-containing unfired refractory layers and one or more fired refractory layers are provided from the working surface side that contacts the molten metal to the iron skin side. In the drying method of the lining, which is formed and the fired refractory layer is formed on the back side which is the iron skin side of the water-containing unfired refractory layer,
The measurement temperature Ts (° C.) on the most operating side of the water-containing unfired refractory layer, the measurement temperature Tb (° C.) on the backmost side of the water-containing unfired refractory layer, and the water-containing unfired refractory layer The temperature gradient (Ts−Tb) / t in the thickness direction of the water-containing unfired refractory layer calculated from the thickness t (mm) is more than 0 and 0.5 (° C./mm) or less. When the lining is heated and dried from at least the working surface side (however, the lining is heated and dried except when microwaves are used) until the back surface temperature of the hydrous unfired refractory layer reaches 110 ° C. The heating rate when heating the operating surface of the water-containing unfired refractory layer from 100 ° C. to 200 ° C. is 40 ° C. or less per hour.

In the method for drying a lining according to the present invention, a plurality of the fired refractory layers are provided on the iron skin side of the water-containing unfired refractory layer, and at least one layer of the fired non-fired refractory layer is provided on the back side. It is preferable to arrange the heat insulating material through the fired refractory layer.

The drying method of the lining according to the present invention is, for example, when constructing an amorphous refractory as a wear refractory, or repairing a used refractory with an undried amorphous refractory (repair material), etc. When drying the hydrous unfired refractory layer formed with this amorphous refractory, the temperature gradient was set to more than 0 and 0.5 (° C / mm) or less, so that the explosion of the hydrous unfired refractory layer was suppressed. Further, it can be prevented. Furthermore, as described above, the present invention aims to prevent explosion by defining the temperature gradient of the water-containing unfired refractory layer. Therefore, the type of the water-containing unfired refractory used for the formation of this layer. Regardless of (for example, casting material, shot material, trowel coating material, spraying material, etc.), explosion of the water-containing unfired refractory layer can be stably prevented.

In addition, when a heat insulating material is disposed in the lining and the heat insulating material is disposed on the back side of the water-containing unfired refractory layer via at least one fired refractory layer, moisture in the water-containing unfired refractory layer Deterioration of the heat insulating material due to absorption can be suppressed. This makes it possible to increase the heating rate of the water-containing unfired refractory layer while maintaining the temperature gradient of the water-containing unfired refractory layer within the above-mentioned predetermined range, thereby suppressing explosion while shortening the drying time. Further, it can be prevented.

It is a sectional side view of the furnace wall structure of the molten metal container to which the drying method of the lining which concerns on one embodiment of this invention is applied.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
First, the background of the lining drying method of the present invention will be described.
The inventors of the present invention have made various studies to realize the suppression of explosion occurrence more than the above-described prior art, and have considered that explosion occurs by the following mechanism.
As preconditions, moisture-containing non-fired refractory layer (undried wear refractory or repair material) and fired refractory layer placed on the back side (permanent refractory of regular refractory, or fired by use It is assumed that the moisture-containing unfired refractory layer is dried with the layer structure of the amorphous refractory in the state.

When drying is carried out by bringing a hot gas into contact with the working surface (hereinafter also referred to as the surface) of the water-containing unfired refractory layer, first, the temperature of the working surface of the water-containing unfired refractory layer rises and is delayed in time. The temperature of the center in the thickness direction (hereinafter also simply referred to as the center), and the temperature of the back surface (the surface side of the fired refractory layer) rises with a delay in time.
Here, considering the temperature rise in the central part of the hydrous unfired refractory layer, the internal pressure (hereinafter referred to as vapor pressure) in the central part increases due to the water vapor generated as the temperature rises. If the value of exceeds the fracture strength of the amorphous refractory, it is considered that explosion occurs.
The value of this vapor pressure is the amount of water vapor generated per unit time in the center of the water-containing unfired refractory layer, and the unit in which the generated water vapor is discharged from the center of the water-containing unfired refractory layer to its working surface or back. It is thought to be determined by the balance with the amount of water vapor discharged per hour.

Since the amount of water vapor generated per unit time is determined by the heat input at the center of the water-containing unfired refractory layer, it is generally determined by the temperature gradient of the water-containing unfired refractory layer. That is, in order to increase the value of the vapor pressure, it is essential that the temperature gradient is large.
Moreover, the amount of water vapor discharged per unit time is the pressure loss when water vapor passes through the central part of the water-containing unfired refractory layer (that is, the working surface side or the back side in the water-containing unfired refractory layer). That is, it is determined by the state of generation of pores in the water-containing unfired refractory layer (pore generation by the progress of water evaporation). When this moisture-containing unfired refractory layer is heated and dried from the working surface side, substantially, when the working surface portion of the moisture-containing unfired refractory layer is dried, the water vapor in the center of the moisture-containing unfired refractory layer is increased. Emissions will increase. Therefore, when the temperature of the working surface portion of the water-containing unfired refractory layer is increased to promote drying, that is, when the temperature gradient of the water-containing unfired refractory layer is large, the discharge of water vapor proceeds.

From the above, it can be seen that both the increase of the vapor pressure and the discharge of the water vapor (reduction of the vapor pressure) require that the temperature gradient has a predetermined value.
In the region where the temperature gradient exceeds 0 and is 0.5 (° C./mm) or less, the present inventors have noticeable steam discharge compared to the amount of steam generated from the water-containing unfired refractory layer, and the increase in steam pressure. It has been found that explosion can be suppressed without becoming noticeable, and in the region of more than 0.5 (° C./mm), the amount of water vapor generation becomes remarkable and easily leads to the explosion phenomenon (generation of many microcracks). Specifically, the heating at which the temperature gradient exceeds 0 and becomes 0.5 (° C./mm) or less is performed until the back surface temperature of the hydrous unfired refractory layer reaches 110 ° C. (that is, from the start of heating to the back surface temperature). (Until 110 ° C. is reached). This is because water (water vapor) that causes explosions is considered to remain in the hydrous unfired refractory layer until the back surface temperature of the hydrous unfired refractory layer exceeds at least 100 ° C. This is because it is considered appropriate that water is removed from the drying target when the back surface temperature of the hydrous unfired refractory layer reaches 110 ° C.

Although the above-mentioned Patent Document 3 can suppress explosion to some extent by managing the absolute value of the temperature, if the temperature difference in the thickness direction of the wear refractory, that is, the temperature gradient (° C./mm) becomes large, the temperature gradient is increased. As a result, explosions may occur in the ware refractory during drying, and no measures are taken for this problem.
Moreover, although the Example of patent document 3 and the invention example of the wear refractory from which thickness differs are described (invention example: 200 mm, the conventional example: 230 mm), back surface temperature near 100 degreeC which water vapor | steam generate | occur | produces is described. Up to this point, since the temperature gradient of the wear refractory is larger in the example of the invention, the effect of preventing explosion by reducing the temperature gradient cannot be obtained. Specifically, in FIG. 3 of Patent Document 3, the temperature difference between the operating surface and the back surface of the ware refractory at a dehydration completion temperature (water vapor pressure is not high) around 110 ° C. is considered to be about 120 ° C. In the example, since the thickness is 200 mm, the temperature gradient is 0.60 ° C./mm, and in the conventional example, the thickness is 230 mm, so the temperature gradient is 0.52 ° C./mm. In this case, even if the drying time can be shortened and cracking or peeling during actual use can be prevented, explosion due to water evaporation may occur during drying.

Next, a molten metal container to which a lining drying method according to an embodiment of the present invention is applied will be described, and then a lining drying method will be described.
As shown in FIG. 1, the molten metal container 10 contains water from the working surface 12 side (furnace inner side) in contact with the molten metal (not shown) to the iron skin 11 side (furnace outer side). The non-fired refractory layer 13 and the fired refractory layer (first fired refractory layer 14) have a lining 15 formed in order, and the lining 15 is heated and dried. Examples of the molten metal container include a converter, a hot metal ladle, a molten steel pan, and an electric furnace.

The hydrous unfired refractory layer 13 is a refractory layer composed of undried wear refractory or a repair material (that is, an amorphous refractory obtained by kneading with water at room temperature). This undried ware refractory layer is a water-containing unfired refractory used as a ware refractory, and this water-containing unfired refractory is used as a pouring material, etc., provided on the working surface side of the fired refractory layer. It is a refractory layer. In addition, the undried repair material layer is a water-containing non-fired refractory layer on the operating surface side of the remaining wear refractory (used here as the first fired refractory layer 14) once used in a molten metal container or the like. When repairing with an object, this moisture-containing unfired refractory is used as, for example, a spraying material, a shot material, or a trowel coating material, and is a refractory layer provided on the operating surface side of the wear refractory.
In addition, although the case where one water-containing unfired refractory layer was formed was described here, two or more layers can be formed from the working surface side to the iron skin side. In this case, the material and formation method (construction method) of each layer may be the same or different.

The component system of the hydrous unfired refractory includes, for example, magnesia-lime, alumina-magnesia, alumina-spinel, alumina-silica, siliceous, alumina-silicon carbide, clay, etc. It is not limited. Also, the curing method of the hydrous unfired refractory is not limited to hydraulic properties using a hydration reaction like alumina cement, and may be any of chemical curing properties, thermosetting properties, and pneumatic properties, and is particularly limited. is not.
The thickness of the water-containing unfired refractory layer 13 (total thickness in the case where a plurality of layers are formed) can be variously changed depending on the application (construction method), and is not particularly limited. When constructing the refractory as a wear refractory, for example, it is about 200 mm or less, and when repairing the operating surface of the wear refractory, for example, it is about 200 mm or less (particularly, 150 mm or less). In addition, if a water-containing unfired refractory layer is disposed on the surface of the fired refractory layer, the lower limit of the water-containing unfired refractory layer is a thickness exceeding 0 mm, but usually 5 mm or more, 10 mm or more.

The first fired refractory layer 14 is a refractory layer composed of a permanent refractory or a fired amorphous refractory. This permanent refractory layer is a refractory layer generally formed of a fired regular refractory (standard refractory), and the fired amorphous refractory layer is used and fired as described above. It is a refractory layer formed of an irregular refractory.
The material of the fired refractory is not particularly limited, but the fired refractory layer is melted at a high temperature when the fired water-containing unfired refractory layer disposed on the working surface side melts and peels off. Since there is a possibility of coming into contact with an object, a highly fire-resistant wax or alumina is generally used.
In addition, the thickness of the first fired refractory layer 14 can be variously changed according to the application (construction method) and is not particularly limited. However, in general, for example, the upper limit is 100 mm (particularly 70 mm). The lower limit is 30 mm.

As described above, the component system of the amorphous refractory constituting the water-containing unfired refractory is not particularly limited, but the carbon-containing amorphous refractory is used for the water-containing unfired refractory. In this case, the effect of the present invention, that is, the effect of preventing the explosion of the water-containing unfired refractory is diminished. This amorphous refractory containing carbon has a high thermal conductivity of the amorphous refractory itself, so that the temperature gradient in the amorphous refractory is reduced. In this case, since the heating rate of the water-containing unfired refractory layer can be increased and the water-containing unfired refractory layer can be heated, for example, the heating time can be shortened.
In addition, the effect of preventing the explosion of the water-containing unfired refractory is remarkably obtained when an amorphous refractory having a thermal conductivity of 10 W / (m · K) or less is used. The lower limit of the thermal conductivity of the amorphous refractory is, for example, about 0.1 W / (m · K) in consideration of the thermal conductivity of the amorphous refractory existing in the world.

On the iron skin 11 side of the first fired refractory layer 14 (working surface side refractory) described above, the heat insulating material 16 and the second fired refractory layer 17 (iron skin side refractory) are directed toward the iron skin 11 side. Are sequentially arranged. In this way, a plurality of fired refractory layers (first and second fired refractory layers 14 and 17) are provided on the side of the iron skin 11 of the water-containing unfired refractory layer 13, and the water-containing unfired refractory layer 13 is provided. The 1st fired refractory layer 14 is formed in the back side. That is, the first and second fired refractory layers 14 and 17 are disposed on the back surface of the water-containing unfired refractory layer 13 (the back surface of the water-containing unfired refractory layer located closest to the iron skin when a plurality of layers are formed). Of these, the first fired refractory layer 14, which is one layer closest to the working surface 12, is disposed adjacent to (adjacent to). In addition, forming on the back side means arrange | positioning adjacent to an iron-skin side.
The structure of the second fired refractory layer 17 can also be made of the same material as that of the first fired refractory layer 14 described above.
In general, the heat insulating properties of the heat insulating material decrease due to contact with water. Therefore, the heat insulating material directly contacts the water-containing unfired refractory layer 13, that is, the water-containing unfired refractory layer 13 and the first fired refractory layer 14. Place between them should be avoided. Further, even if the heat insulating material is disposed between the iron shell 11 and the second fired refractory layer 17, the further explosion prevention effect of the water-containing unfired refractory layer 13 cannot be obtained.
From the above, in order to stably obtain the effect of the heat insulating material 16, the heat insulating material 16 was disposed at the above-described position.

The material constituting the heat insulating material is, for example, a fibrous material mainly composed of glass, silica, alumina or the like, an inorganic substance having a microporous structure, or the like. The heat insulating material is preferably in the form of a sheet (plate) having a uniform thickness, and its thermal conductivity is preferably 0.15 W / (m · K) or less at room temperature. An example of such a heat insulating material is “Porextherm WDS (registered trademark)” manufactured by Porextherm Damstoff GmbH. The material is a microporous molded body mainly composed of fumed silica, and the thermal conductivity is 0.021 W / (m · K).
For the reason described above, when the heat insulating material 16 is disposed, it is sufficient that at least one fired refractory layer is disposed between the water-containing unfired refractory layer 13 and the heat insulating material 16, for example, Two or more (multiple layers) fired refractory layers of the same or different materials may be disposed. The total thickness of the plurality of fired refractory layers is the thickness of the first fired refractory layer 14 described above.
On the other hand, when the heat insulating material 16 is not disposed, two or more (multiple layers) of fired refractory layers can be formed from one layer or the working surface side toward the iron skin side. As described above, when a plurality of layers are formed, the material of each layer may be the same or different. In this case as well, the total thickness of the plurality of fired refractory layers is set to a thickness corresponding to the thickness of the first fired refractory layer 14 described above.

As described above, the lining 15 having the above-described configuration is heated and dried so that the temperature gradient in the thickness direction of the hydrous unfired refractory layer 13 exceeds 0 and is 0.5 (° C./mm) or less. Yes. In addition, when a plurality of hydrous unfired refractory layers are formed, a temperature gradient in the entire thickness is obtained.
In order to realize the value of this temperature gradient, the amount of heat input during heating may be controlled (for example, controlling the amount of combustion gas supplied to the burner, etc.) while measuring the temperature gradient of the hydrous unfired refractory layer. Further, in order to avoid a sudden temperature gradient, the lining 15 can be heated not only from the operating surface side of the lining 15 but also from the operating surface side and the back surface (for example, the iron skin 11) side. Furthermore, it can also suppress that it becomes a big temperature gradient value by putting the molten metal container 10 which is a to-be-dried object into oven, and drying.
This drying generally has a large heat input from the working surface of the water-containing unfired refractory layer compared to the iron skin side, but when suppressing heat loss from the back of the water-containing unfired refractory layer of the heat input, Even when the temperature gradient is lower in the above range, the time until the drying is completed can be shortened.

Therefore, in order to suppress the heat loss and complete the drying in a short time, as described above, it is preferable to arrange a heat insulating material on the back side of the water-containing unfired refractory layer. However, if it is not necessary to shorten the time until completion of drying, the heat insulating material may not be arranged. In addition, when not arrange | positioning a heat insulating material, although it is not necessary to arrange | position the 2nd baking refractory layer 17, you may arrange | position.
Other methods for realizing the value of the temperature gradient include, for example, heating while measuring the temperature gradient (controlling heat input to the lining during drying) and a method using a lining configuration.
For example, the thickness of the moisture-containing unfired refractory layer to be dried and the thickness of the fired refractory layer disposed between the moisture-containing unfired refractory layer and the heat insulating material can be used for the method of utilizing the configuration of the lining. There is a method of thinning, and this tends to lower the value of the temperature gradient.
Further, the heat passage rate (also referred to as heat transmittance) of the heat insulating material may be reduced (heat insulating property is improved). The heat passage rate is a value obtained by dividing the thermal conductivity by the thickness (= thermal conductivity / thickness).

Although the application part of the lining structure shown above is not specifically limited, When using a heat insulating material, it is desirable to apply to the furnace wall (side wall) of a molten metal container. This is because the refractory to be installed inside the furnace than the heat insulating material, that is, the moisture content of the unfired refractory layer and the first fired refractory layer, the heat insulating material is not deteriorated in the heat insulating performance, and the desired effect is obtained. By being done.
On the other hand, when the lining structure is applied to the furnace bottom (laying part), the weight of the refractory applied to the inside of the furnace from the heat insulating material exceeds the compressive strength of the heat insulating material, and the pore structure of the heat insulating material is destroyed. It causes a decrease and the desired effect is reduced. However, since there is an effect of preventing explosion, a lining structure may be used at the bottom of the furnace.
In addition, the lining structure is preferably applied to the entire furnace wall and / or the bottom of the molten metal container, but may be partially installed only in a part where an effect of preventing explosion is obtained.

Next, a lining drying method according to an embodiment of the present invention will be described with reference to FIG.
When constructing a hydrous unfired refractory as a ware refractory, first, for example, a second fired refractory layer 17 of a rectangular parallelepiped, a trapezoidal column, or a trapezoidal base is formed on the furnace inner surface of the iron skin 11 through a joint. Many linings are used without gaps.
Next, the sheet-like heat insulating material 16 is bonded to the inner surface of the second baked refractory layer 17 which is lined so that no gap is formed between the adjacent heat insulating materials 16.
A large number of first fired refractory layers 14 are lined on the furnace inner surface of the heat insulating material 16 bonded to the surface of the second fired refractory layer 17 without any gaps. Further, a thermocouple 18 is installed on the inner surface of the first fired refractory layer 14 that is lined.
In addition, when not installing a heat insulating material, the installation work of the above-mentioned heat insulating material 16 can be omitted, and the installation work of the second fired refractory layer 17 may be omitted. The first fired refractory layer 14 can also be directly lined on the furnace inner surface.

In this way, after the thermocouple 18 is installed, a mold (not shown) is installed inside the furnace of the first fired refractory layer 14 with a space, and a hydrous unfired refractory is poured into this space. The water-containing unfired refractory layer 13 is formed on the working surface side of the first fired refractory layer 14. And it is the working surface 12 of the formed water-containing unfired refractory layer 13, and is substantially the same height position facing the above-mentioned thermocouple 18 (particularly, the thickness of the formed water-containing unfired refractory layer 13 is the thickest). A thermocouple 19 is installed at the height position.
The number of thermocouples 18 and 19 to be paired is not particularly limited, and one or a plurality of two or more thermocouples 18 and 19 can be installed depending on the location where temperature measurement is required.
As described above, the moisture-containing unfired refractory layer 13, the first fired refractory layer 14, the heat insulating material 16, and the second fired refractory layer are formed on the furnace inner surface of the iron skin 11 from the furnace inner side toward the furnace outer side. After arrange | positioning in order of 17, this lining 15 is heated and dried from the furnace inner side (water-containing unfired refractory layer 13 side) and further from the furnace outer side (iron skin 11 side).

The heating of the lining 15 is such that the temperature gradient in the thickness direction of the hydrous unfired refractory layer 13 exceeds 0 and is 0.5 (° C./mm) or less (preferably, the lower limit is 0.1 (° C./mm), and the upper limit is To 0.48 (° C./mm)). Specifically, the measurement temperature Ts (° C.) of the thermocouple 19 installed closest to the operating surface 12 of the water-containing unfired refractory layer 13 and the measurement temperature Tb (° C.) of the thermocouple 18 installed closest to the back surface. ), And the temperature gradient (= (Ts−Tb) / t) calculated from the thickness (corresponding to the distance between the thermocouple 18 and the thermocouple 19) t (mm) of the hydrous unfired refractory layer 13 is The lining 15 is heated so as to be within the above-described range.
Here, as a heating method that can be used for drying, for example, there is a method of supplying a heat source in one direction or concentric circles such as burner heating, hot air heating, hot air heating, radiant heating (radiant tube), and the like. The method is not particularly specified. When heating is performed, a method using a lid that can accurately follow a predetermined temperature rising pattern and can cover the open top portion of the molten metal container is generally used.

The heating rate that can be achieved by these heating methods, specifically, when the drying surface (working surface) of the hydrous unfired refractory layer is heated from 100 ° C. to 200 ° C., the drying surface can be heated uniformly. The temperature rate is, for example, a rate at which the drying surface temperature of the water-containing unfired refractory layer is 40 ° C. or less per hour, that is, 40 (° C./hour) or less (further 35 (° C./hour) or less). On the other hand, the lower limit value of the heating rate is not particularly limited, but is 5 (° C./hour), and further 10 (° C./hour), considering that drying is performed in a shorter time.
As described above, by heating and drying the formed lining 15, explosion during drying of the water-containing unfired refractory layer 13 formed of the wear refractory can be suppressed and further prevented.

In the use of the above-described molten metal container, the fired, water-containing unfired refractory layer that comes into contact with the molten metal is damaged and thinned by various factors such as melting, wear, and peeling.
Therefore, in this case, the used wear refractory that has been damaged and has received the remaining heat history is repaired with an undried amorphous refractory (repair material). Hereinafter, the ware refractory to be repaired will be described as the first fired refractory layer 14, and the undried amorphous refractory will be described as the water-containing unfired refractory layer 13.
First, the thermocouple 18 is installed on the reduced thickness damaged portion, that is, on the surface of the first fired refractory layer 14.
In this way, after the thermocouple 18 is installed, the water-containing unfired refractory is disposed on the furnace inner surface of the first fired refractory layer 14 to form the water-containing unfired refractory layer 13. Here, it is the working surface 12 of the formed water-containing unfired refractory layer 13 and is at substantially the same height position facing the thermocouple 18 described above (in particular, the thickness of the formed water-containing unfired refractory layer 13 is the largest. The thermocouple 19 is installed at a height position).
The number of thermocouples 18 and 19 installed is the same as described above.

Here, when forming the water-containing unfired refractory layer 13 at the damaged site, a kneaded or mixed amorphous refractory can be used.
In addition, when using the kneaded amorphous refractory, there are the following construction methods.
1) Moisture and refractory material are kneaded in advance (in advance), and then this kneaded product is conveyed to the damaged site (repaired portion) with a hose or the like, and is applied to the damaged site (the surface of the first fired refractory layer 14). Spray (shot repair).
2) After transporting moisture and refractory material separately to the repaired part with a hose, etc., the amorphous refractory mixed in the vicinity of the spout such as this hose is applied to the damaged part (the surface of the first fired refractory layer 14). Spray (spray repair).
3) After kneading moisture and a refractory material in advance (in advance), the kneaded material is applied to the damaged part (the surface of the first fired refractory layer 14) with a trowel (trowel coating repair).
As described above, there are various repair methods, but they can be selected according to a desired repair method.
In addition, when forming a plurality of water-containing unfired refractory layers, only one of the above-described construction methods or a combination of two or more can be used.

Thus, after forming the water-containing unfired refractory layer 13 at the damaged site, the water-containing unfired refractory layer 13 is dried from the inside of the furnace (the working surface side of the water-containing unfired refractory layer 13).
The lining 15 is heated by a method similar to the above so that the temperature gradient in the thickness direction of the water-containing unfired refractory layer 13 exceeds 0 and is 0.5 (° C./mm) or less. When a plurality of water-containing unfired refractory layers are formed, the lining is heated so that the temperature gradient over the entire thickness of the plurality of water-containing unfired refractory layers is within the above-described range.
As described above, by heating and drying the formed lining 15, explosion during drying of the water-containing unfired refractory layer 13 formed of an amorphous refractory can be suppressed and further prevented.
Therefore, the mechanism that the present inventors have conceived is that the easiness of explosion can be explained by a temperature gradient, such as a casting material, a shot material, a trowel coating material, a spraying material, etc., having different moisture contents. The moisture-containing unfired refractory used in the construction method (repair method) has the advantage of being able to suppress explosion during drying using the same management method.

Next, examples carried out for confirming the effects of the present invention will be described.
First, a refractory was lined as the lining of a cylindrical container.
This lining is disposed on the furnace inner surface of the iron shell of the cylindrical container from the inside of the furnace to the outside of the furnace, in order of the water-containing unfired refractory layer and the first fired refractory layer, and further the first firing. The heat-insulating material and the second fired refractory layer were arranged in this order on the outside of the furnace of the refractory layer. Here, an alumina-magnesia amorphous refractory is used for the water-containing unfired refractory layer, a high-alumina shaped refractory is used for the first fired refractory layer, and a second fired refractory layer is used. Each stone shaped refractory was used.

In addition, when performing the above-mentioned lining, when constructing the moisture-containing unfired refractory as a wear refractory, and when repairing the used ware refractory with an undried moisture-containing unfired refractory (repair material), Location of application of lining, each thickness of water-containing unfired refractory layer and first fired refractory layer, presence or absence of heat insulating material and arrangement position and its heat transmission rate, construction method of water-containing unfired refractory layer, heating method Various changes were made.
Then, the lining is heated and dried from room temperature, and at the timing when the back surface temperature of the water-containing unfired refractory layer containing water reaches 110 ° C. and dehydration is completed (no steam is generated), the inside of the water-containing unfired refractory layer The temperature gradient (° C./mm) and the occurrence of peeling and explosion troubles were investigated.

Table 1 shows the test conditions, the temperature gradient of the obtained water-containing unfired refractory layer, and the results of the occurrence of peeling and explosion troubles, respectively.
Table 1 shows typical conditions when peeling and explosion do not occur and when peeling occurs. As for explosion, the conditions under which explosion occurred in the drying data for the past 5 years are described. However, when an oven is used for heating the lining, no explosion occurred in the water-containing unfired refractory layer, so the conditions for the explosion using the oven are not described.

In the column of the construction position of the heat insulating material shown in Table 1, “A” means “B” when the heat insulating material is disposed between the first fired refractory layer and the second fired refractory layer. Is the case where the heat insulating material is arranged between the iron skin and the second fired refractory layer, and “−” means that the inside of the iron skin is not provided without providing the heat insulating material and the second fired refractory layer. The case where the 1st baking refractory layer is arrange | positioned on the surface is each meant.
In addition, the temperature gradient of the water-containing unfired refractory layer is such that the back surface temperature of the water-containing unfired refractory layer reaches 110 ° C. and the dehydration is completed (no water vapor is generated). The value obtained by subtracting the back surface temperature from the temperature divided by the thickness of the hydrous unfired refractory layer, that is, the value obtained by the following equation.
{(Operating surface temperature of hydrous unfired refractory layer) − (Back surface temperature of hydrous unfired refractory layer)} / (Thickness of hydrous unfired refractory layer)
Here, the operating surface temperature and the back surface temperature of the water-containing unfired refractory layer and the thickness of the water-containing unfired refractory layer were obtained by the method described in the above embodiment.

And, in the column of the construction method, “pouring” means a method in which a mold is placed with a space inside the furnace of the first fired refractory layer, and the water-containing unfired refractory is poured into this space. “Blowing” and “shot” respectively mean a method of spraying the water-containing unfired refractory onto the furnace inner surface of the first fired refractory layer, as described in the above embodiment. Note that, as described above, “spraying” and “shot” are different in the mixing time of water and refractory material for producing a water-containing unfired refractory.
Here, the water content in the water-containing unfired refractory used in each method is about 4% by mass or more and 9% by mass or less in the outer casting method of the refractory material constituting the water-containing unfired refractory. In the method, it is about 20% by mass or more and 25% by mass or less by outer coating, and in the shot method, it is about 10% by mass or more and 15% by mass or less by outer coating.

Moreover, in the column of the heating method, “a” means that when the lining is heated from room temperature and dried, the operating surface temperature of the water-containing unfired refractory layer is increased at a constant rate of 40 (° C./hour). In the case where the lining is heated from the inside of the furnace using a burner, “b” means that the lining is made using a burner smaller than the burner inside the furnace (candle burner) in addition to the above-mentioned condition “a”. In the case of heating from the outside of the furnace (iron skin surface), “c” means the case where the constant temperature increase is changed to 10 (° C./hour) under the above-mentioned condition “a”.
In addition, as described above, the temperature rise when the operating surface temperature of the hydrous unfired refractory layer is 40 (° C./hour) is when the dry surface is heated from 100 ° C. to 200 ° C. in the heating of the burner described above. In addition, it is the fastest heating rate that can be uniformly heated.
In the column of occurrence / non-existence of delamination / explosion trouble, “none” means no occurrence of delamination or explosion trouble, and “yes” means occurrence of delamination or explosion trouble.

First, the case where a hydrous unfired refractory is constructed as a ware refractory (casting construction) will be described with reference to Examples 1 to 6 and Comparative Examples 1 to 5 in Table 1.
In Table 1, Examples 1-6 are the results of adjusting the temperature gradient in the thickness direction of the water-containing unfired refractory layer to 0.5 (° C./mm) or less, while Comparative Examples 1-5 are It is the result of adjusting the temperature gradient in the thickness direction of the water-containing unfired refractory layer to more than 0.5 (° C./mm).
As is clear from Table 1, by adjusting the temperature gradient in the thickness direction of the water-containing unfired refractory layer to 0.5 (° C./mm) or less, peeling of the water-containing unfired refractory layer and occurrence of explosion problems I found that it can be prevented.
Below, various changes are made to the application location of the lining, the presence or absence of a heat insulating material (arrangement position and heat transmission rate), each thickness of the water-containing unfired refractory layer and the first fired refractory layer, and the method of heating the water-containing unfired refractory layer The effect will be described in more detail.

First, the result of changing the construction site of the lining will be described.
Since Example 1 is the result of constructing the heat insulating material on the wall portion, it was possible to prevent the heat insulating performance of the heat insulating material from being deteriorated by the dead weight of the refractory layer applied to the inside of the furnace from the heat insulating material. On the other hand, since Example 5 is the result of constructing the heat insulating material on the bottom, the heat insulating performance of the heat insulating material deteriorated due to the weight of the refractory layer applied to the inside of the furnace from the heat insulating material.
For this reason, it is considered that the temperature gradient of the water-containing unfired refractory layer could not be kept small in Example 5 compared with Example 1, and the heat insulating material was applied to the wall as in Example 1. It was confirmed that the effect of keeping the temperature gradient of the water-containing unfired refractory layer small was greater.

Next, the presence or absence of a heat insulating material and the result of changing the construction position will be described.
From the results of Example 1 and Comparative Examples 1 and 2, it was confirmed that the temperature gradient of the water-containing unfired refractory layer can be reduced by constructing a heat insulating material near the heat source, that is, near the water-containing unfired refractory layer. did it.
Moreover, the result of having changed the heat passage rate of the heat insulating material is demonstrated.
From the results of Examples 1 and 2 and Comparative Example 3, the temperature gradient of the water-containing unfired refractory layer is reduced as the heat passage rate of the heat insulating material is smaller (the thermal conductivity is lower or the construction thickness of the heat insulating material is larger). It was confirmed that it could be made smaller.

Next, the result of changing the thickness of the hydrous unfired refractory layer will be described.
From the results of Examples 1 and 4 and Comparative Example 4, it was confirmed that the thinner the thickness of the water-containing unfired refractory layer, the smaller the temperature gradient of the water-containing unfired refractory layer.
Moreover, the result of having changed the thickness of the 1st baking refractory layer is demonstrated.
From the results of Examples 1 and 3 and Comparative Example 5, it was confirmed that the thinner the thickness of the first fired refractory layer, the smaller the temperature gradient of the water-containing unfired refractory layer.
And the result of having changed the heating method of a water-containing unbaked refractory layer is demonstrated.
From the results of Examples 5 and 6, it was confirmed that the temperature gradient of the water-containing unfired refractory layer can be reduced by heating and drying the lining not only from inside the furnace but also from both inside and outside the furnace. did it.

Subsequently, with respect to the case where the wear refractory after use is repaired with water-containing unfired refractory (spray repair, shot repair, pouring repair) while referring to Examples 7 to 12 and Comparative Examples 6 to 11 in Table 1. explain.
In Table 1, Examples 7-12 are the results of adjusting the temperature gradient in the thickness direction of the water-containing unfired refractory layer to 0.5 (° C./mm) or less, while Comparative Examples 6-11 are: It is the result of adjusting the temperature gradient in the thickness direction of the water-containing unfired refractory layer to more than 0.5 (° C./mm).
As is clear from Table 1, by adjusting the temperature gradient in the thickness direction of the water-containing unfired refractory layer to 0.5 (° C./mm) or less, peeling of the water-containing unfired refractory layer and occurrence of explosion problems I found that it can be prevented.
Hereafter, various changes were made to the presence or absence of the heat insulating material (arrangement position and heat transmission rate), each thickness of the water-containing unfired refractory layer and the first fired refractory layer, the construction method of the water-containing unfired refractory layer and its heating method. The influence will be described in more detail.

First, the presence or absence of a heat insulating material and the result of changing the construction position will be described.
From the results of Example 7 and Comparative Examples 6 and 7, it was confirmed that the temperature gradient of the water-containing unfired refractory layer can be reduced by constructing a heat insulating material near the heat source, that is, near the water-containing unfired refractory layer. did it.
Moreover, the result of having changed the heat transmittance of the heat insulating material will be described.
From the results of Examples 7 and 8 and Comparative Example 8, the temperature gradient of the water-containing unfired refractory layer is decreased as the heat transmission rate of the heat insulating material is smaller (the thermal conductivity is lower or the heat insulating material is thicker). It was confirmed that it could be made smaller.
And the result of having changed the thickness of a water-containing unbaked refractory layer is demonstrated.
From the results of Examples 7 and 9 and Comparative Example 9 and the results of Example 11 and Comparative Example 11, it was confirmed that the thinner the water-containing unfired refractory layer, the smaller the temperature gradient of the water-containing unfired refractory layer. did it.

Next, the result of changing the thickness of the first fired refractory layer will be described.
From the results of Examples 7 and 10 and Comparative Example 10, it was confirmed that the thinner the thickness of the first fired refractory layer, the smaller the temperature gradient of the water-containing unfired refractory layer.
Moreover, the result of having changed the construction method of a water-containing unbaked refractory layer is demonstrated.
From the results of Examples 10 and 11, even if the construction method of the water-containing unfired refractory layer is changed, that is, the moisture content in the water-containing unfired refractory layer is changed, It was confirmed that the explosion trouble can be prevented.
And the result of having changed the heating method of a water-containing unbaked refractory layer is demonstrated.
From the results of Example 12, when the lining was heated from room temperature and dried, the lining was heated in a furnace using a burner so that the operating surface temperature of the water-containing unfired refractory layer was raised at a constant speed of 10 (° C / hour). It was confirmed that the temperature gradient of the water-containing unfired refractory layer can be reduced by heating from the inside (that is, by slowing the heating rate of the water-containing unfired refractory layer).

From the above, by using the drying method of the lining of the present invention, the formed lining is heated and dried, thereby causing explosion during drying of the hydrous unfired refractory layer formed of the wear refractory and its repair material. It was confirmed that it could be suppressed and further prevented.

As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included. For example, a case where the drying method of the lining of the present invention is configured by combining some or all of the above-described embodiments and modifications is also included in the scope of the right of the present invention.
Further, in the above-described embodiment, the case where the lining drying method of the present invention is applied to a molten metal container is described. However, the present invention is not limited to this as long as the lining is to be performed. Good.

10: molten metal container, 11: iron skin, 12: working surface, 13: water-containing unfired refractory layer, 14: first fired refractory layer, 15: lining, 16: heat insulating material, 17: second fired refractory Material layer, 18, 19: Thermocouple

Claims (2)

One or more water-containing unfired refractory layers and one or more fired refractory layers are formed from the working surface side in contact with the molten metal to the iron skin side, and the iron of the water-containing unfired refractory layer In the drying method of the lining in which the fired refractory layer is formed on the back side which is the skin side,
The measurement temperature Ts (° C.) on the most operating side of the water-containing unfired refractory layer, the measurement temperature Tb (° C.) on the backmost side of the water-containing unfired refractory layer, and the water-containing unfired refractory layer The temperature gradient (Ts−Tb) / t in the thickness direction of the water-containing unfired refractory layer calculated from the thickness t (mm) is more than 0 and 0.5 (° C./mm) or less. When the lining is heated and dried from at least the working surface side (however, the lining is heated and dried except when microwaves are used) until the back surface temperature of the hydrous unfired refractory layer reaches 110 ° C. A method for drying a lining, characterized by heating at a temperature gradient and heating a working surface of the water-containing unfired refractory layer from 100 ° C to 200 ° C at a heating rate of 40 ° C or less per hour . 2. The method for drying a lining according to claim 1, wherein a plurality of the fired refractory layers are provided, and a heat insulating material is disposed on the back side of the water-containing unfired refractory layer via at least one fired refractory layer. A method of drying a lining characterized by.

Images