JP6380509B2 - Heat retaining method, residual thickness measuring method, and heat retaining device for molten metal carrying container - Google Patents

Description

  The present invention maintains a molten metal carrying container that can prevent a temperature drop in the molten metal carrying container after the molten metal (eg, molten steel) is released from the molten metal carrying container (eg, molten steel carrying container). The present invention relates to a heat method, a remaining thickness measurement method, and a heat retention device.

  In the steel industry, in order to refining and transporting molten steel, a molten steel transport container for containing and transporting molten steel is used. A specific example of such a molten steel carrying container is a ladle that receives molten steel refined in a converter. The ladle receives the molten steel from a converter or the like, then is transported to a casting facility, and then the molten steel is discharged from the bottom nozzle. After steel output, it is transported to the bottom of the converter to receive the steel again from the converter, but in recent years, after the steel output, repair of the refractory that forms the inner wall of the ladle and the remaining thickness Measurements are made frequently.

  Refractory repairs and residual thickness measurements are performed with the ladle sideways. In such a state, the temperature of the surface of the refractory forming the inner wall of the ladle is lowered by the heat dissipating through the opening of the ladle. Moreover, the temperature of the refractory surface which forms the inner wall of a ladle rises at the time of receiving the molten steel performed next. If there is a large temperature difference in the ladle between repairing refractories and measuring the remaining thickness, and receiving molten steel, the refractory inside the ladle will be damaged by thermal fatigue as the temperature rises and falls repeatedly. There is a problem that damage such as cracking occurs.

  As disclosed in Patent Document 1 and the like, as a means for reducing the temperature change of the surface of the refractory in the ladle, after the molten steel is removed, a lid is applied to the opening of the ladle. ing. As such a ladle cover, a member in which a refractory is attached to an iron skin is generally used.

JP 2009-255124 A

  However, in the method described in Patent Document 1, it is necessary to open the lid in order to check the inside of the container when repairing the refractory inside the ladle and measuring the remaining thickness after the molten steel is produced. There is a problem that a sufficient heat retention effect cannot be obtained. Moreover, in the method described in patent document 1, the opening part of a ladle is kept facing upwards, and there also exists a problem that the confirmation inside a ladle is difficult. These problems are the same in the case of molten metals other than molten steel (for example, hot metal, zinc-based plating solution).

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a heat retaining method for a molten metal carrying container that can suppress a temperature drop on the surface of the internal refractory without installing a lid on the container. A thickness measurement method and a heat retention device are provided.

Means for solving the above problems are as follows.
[1] Using a heat retention device having a plurality of discharge means for discharging a heat retention medium and a support means for supporting the discharge means so that the heat retention medium can be discharged in a downward direction, Distributing means of the heat retaining device is arranged at the front upper part of the opening of the molten metal transporting container which has been stationary, and in front of the opening of the molten metal transporting container from above to below, A heat retaining method for a molten metal carrying container, wherein the heat retaining medium is ejected from a discharging means to make the following temperature drop index less than 1.
(Temperature drop index) = (Temperature drop on the surface of the refractory inside the molten metal carrying container when the heat retaining medium is discharged) / (Temperature of the surface of the refractory inside the molten metal carrying container when the heat retaining medium is not discharged) Descent amount)
[2] The discharge means includes a narrow pipe, the support means includes a pipe for supplying a heat retaining medium to the narrow pipe, and the heat retaining medium supplied by the pipe is discharged from the narrow pipe. The heat retaining method for a molten metal carrying container according to the above [1].
[3] The heat retention method for a molten metal carrying container according to [1] or [2], wherein the discharge unit includes a blower, and a heat retention medium is discharged by the blower.
[4] The heat retention medium is discharged in the direction opposite to the opening of the molten metal carrying container so that the inclination angle θ with respect to the vertical direction is 5 ° ≦ θ ≦ 15 °. The heat retaining method for a molten metal carrying container according to any one of 1] to [3].
[5] The upper lid provided at the opening of the molten steel transport container is removed, the molten metal transport container is tilted sideways, and the molten metal transport container described in any one of [1] to [4] is maintained. Using a heat method, a molten metal carrying container is formed using a residual thickness measuring device installed outside the heat retaining medium layer while forming the heat retaining medium layer in front of the opening of the molten steel carrying container. A method for measuring a remaining thickness of a molten metal carrying container, comprising measuring a remaining thickness of an internal refractory.
[6] Molten metal transport comprising a plurality of discharge means for discharging the heat retaining medium and a support means for supporting the discharge means so that the heat retaining medium can be discharged downward. Container heat retention device.
[7] The heat retention of the molten metal carrying container according to [6], wherein the discharge means includes a narrow pipe, and the support means includes a pipe for supplying a heat retaining medium to the narrow pipe. apparatus.
[8] The heat retention device for a molten metal carrying container according to [6] or [7], wherein the discharge means includes a blower.
[9] The discharge means is attached so that the inclination angle θ is 5 ° ≦ θ ≦ 15 ° in the direction opposite to the opening of the molten metal carrying container with respect to the vertical direction. The heat retaining device for a molten metal carrying container according to any one of [6] to [8].
[10] The molten metal according to any one of [1] to [4], wherein the discharge means has a total discharge flow rate Q of 100 m ³ / min ≦ Q ≦ 200 m ³ / min. How to keep the transport container warm.
[11] In any of the above [1] to [4] or [10], the discharge means has a horizontal distance L1 from the opening surface of the molten metal carrying container of 0.25 m ≦ L1 ≦ 1 m. The heat-retaining method of the molten metal carrying container as described in any one.
[12] From the above [1] to [4] or [10], wherein the discharge means has a vertical distance L2 from the upper end of the opening of the molten metal carrying container of 0.5 m ≦ L2 ≦ 3 m. [11] The heat retention method for a molten metal carrying container according to any one of [11].
[13] The molten metal according to any one of [6] to [9], wherein the discharge means has a total discharge flow rate Q of 100 m ³ / min ≦ Q ≦ 200 m ³ / min. Heat retention device for transport containers.
[14] In any one of [6] to [9] or [13], the discharge means has a horizontal distance L1 from the opening surface of the molten metal carrying container of 0.25 m ≦ L1 ≦ 1 m. A heat retaining device for a molten metal carrying container according to claim 1.
[15] From the above [6] to [9] or [13], wherein the discharge means has a vertical distance L2 from the upper end of the opening of the molten metal carrying container of 0.5 m ≦ L2 ≦ 3 m. [14] The heat retention device for a molten metal carrying container according to any one of [14].

  According to the present invention, it is possible to prevent the temperature of the refractory surface in the molten metal carrying container from being lowered after the molten metal is discharged without providing a lid.

It is explanatory drawing which shows the outline of this invention. It is explanatory drawing which looked at FIG. 1 from the opening part front surface of the molten steel conveyance container. It is the schematic which shows typically the condition where the heat retention medium is discharging from the discharge means. It is the schematic which shows the discharge method of the heat retention medium by a narrow mouth pipe. It is the schematic which shows the discharge method of the heat retention medium by a fan. It is a figure which compares and compares the surface average temperature of the refractory in a ladle with the example of this invention, and the conventional method.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, taking a steelmaking process in a converter as an example.

  FIG. 1 is a schematic view showing a molten metal carrying container (here, a molten steel carrying container) transported to a repair location.

  The ladle 1 which is an example of the molten steel carrying container is carried to a repair place for repairing the internal refractory and measuring the remaining thickness after the molten steel is stored, transported and discharged a predetermined number of times. And in order to implement a work | work more easily, as shown in FIG. 1, the ladle 1 is left still in the state which orient | assigned the opening part 11 sideways. The ladle 1 is provided with an upper lid at the opening 11 when the molten steel is transported, but the upper lid is removed in advance when the ladle 1 is transported to a repair location. With the top cover removed and the opening 11 facing sideways, the heat inside the ladle 1 is radiated horizontally from the opening 11 to the front of the ladle 1, and then the warmed gas rises as an air flow To do.

  Thus, since the heat inside the ladle 1 is generally dissipated from the opening 11 to the outside, the temperature inside the ladle 1 will gradually decrease unless some heat retention measures are taken at the repair location. Become. Once the temperature inside the ladle 1 is lowered, when the molten steel is poured again and the temperature of the ladle rises, the refractory inside the ladle 1 is damaged by the temperature difference. By repeatedly raising and lowering the temperature inside the ladle 1, the refractory may be damaged in the worst case due to thermal fatigue.

  Therefore, as shown in FIG. 1, the heat retaining device 7 is formed by the discharge means 2 and the support means 3 that supports the discharge means 2. The heat retaining device 7 is installed above the ladle 1. The discharge means 2 has a function of discharging the heat retaining medium 4 in front of itself. The heat retaining medium is gas. And the discharge means 2 is attached downward in the support means 3, and discharges the heat retaining medium 4 ahead of the opening part 11 of the ladle 1. As a result, a layer of the heat retaining medium 4 blown out from the discharge means 2 is created in front of the ladle 1. By the layer of the heat retaining medium 4, an air curtain effect that suppresses the heat dissipated in the ladle 1 from the opening 11 is obtained, and the heat in the ladle 1 is suppressed from being dissipated from the opening 11. It is possible to prevent the temperature inside the ladle 1 from being lowered during the work of repairing or measuring the remaining thickness.

  The type of the heat retaining medium 4 is not particularly limited as long as it is a gas, and for example, air can be used. Further, the temperature of the heat retaining medium 4 is not particularly limited as long as it is equal to the temperature of the environment in which the heat retaining device 7 is used.

  In the present invention, the heat retaining medium is discharged from the heat retaining device so that the temperature drop index is less than 1. The temperature drop index is the amount of temperature drop on the surface of the refractory inside the molten steel transport container when the heat retaining medium is discharged with respect to the temperature drop (A) of the surface of the refractory inside the molten steel transport container when the heat retaining medium is not discharged. It is a value which shows the ratio of (B). As the (A) and (B), values actually obtained through experiments can be adopted. For example, the temperature of the surface of the refractory inside the molten steel transport container immediately after the top lid is removed and the ladle is left to stand is set to T1, and then the molten steel transport after 15 minutes has passed without discharging the heat retaining medium. The temperature of the surface of the refractory inside the container is measured as T2. Similarly, the temperature of the surface of the refractory inside the molten steel transport container immediately after removing the lid of the ladle and allowing the ladle to stand sideways is T3, and then 15 minutes have passed since the heat retaining medium was discharged. After that, the temperature of the surface of the refractory inside the molten steel carrying container is measured as T4. The temperature drop index is represented by (T3-T4) / (T1-T2). T1, T2, T3, and T4 may be measured at any location on the inner wall of the molten steel transport container. The timing for measuring T2 and T4 may be any timing at which the difference between T2 and T4 can be detected and the refractory is not subject to adverse effects such as thermal fatigue due to the temperature difference. After 15 minutes have passed since the medium was discharged, or after 15 minutes from when the ladle was allowed to stand sideways. For example, a radiation thermometer can be used to measure the temperature of the refractory surface.

  When the temperature drop index is less than 1, the use of the heat retaining medium as in the present invention prevents the temperature of the surface of the refractory inside the molten steel transport container from becoming lower than when the heat retaining medium is not used. It shows that you can. On the other hand, when the temperature drop index is 1 or more, even if the heat retaining medium is used, the temperature drop on the surface of the refractory inside the molten steel transport container is larger than when the heat retaining medium is not used, and the refractory is damaged. The possibility to do is increased. Therefore, it is important to appropriately set the conditions of the heat retention method so that the temperature drop index is less than 1. Specific examples of conditions include the height at which the ejection means is provided, the number of ejection means, the spread angle of the heat retaining medium ejected from the ejection means, the ejection pressure of the heat retaining medium, and the flow rate of the heat retaining medium. Here, the temperature drop index is preferably less than 0.9, and more preferably less than 0.7. Of course, a smaller temperature drop index can more effectively prevent the temperature of the refractory surface from becoming lower.

  In order to keep the temperature drop index low (increase the heat retention effect inside the molten steel transport container), as shown in FIG. 2, when the opening 11 is viewed from the front, the heat retention medium 4 is discharged with a certain spread. This layer is preferably formed on the entire surface of the opening 11 without any gap.

  In order to lower the temperature drop index, it is preferable to provide the discharge means 2 at a position as close as possible to the opening 11. On the other hand, in order to prevent the temperature inside the ladle 1 from decreasing, it is preferable that the discharge means 2 be too close to the opening 11 so that a part of the heat retaining medium 4 does not enter the ladle 1.

  In the present invention, in order to achieve effective heat retention inside the ladle 1, the installation location of the discharge means 2, the inclination angle and the flow rate of the heat retention medium 4 blown out from the discharge means 2 are particularly important.

  FIG. 3 is a side view showing the relationship between the discharge means 2 and the ladle 1 left to stand sideways. The heat retaining medium 4 is discharged from the discharge means 2 in a direction opposite to the opening 11 of the molten steel carrying container and at an inclination angle θ with respect to the vertical direction. That is, the discharge means 2 is attached so that the heat retaining medium 4 is not discharged toward the opening 11.

  The installation location of the discharge means 2 is such that the horizontal distance L1 from the opening surface of the molten steel carrying container is 0.25 m ≦ L1 ≦ 1 m, and the distance L2 from the upper end of the opening of the molten steel carrying container is 0.5 m ≦ L2 ≦ 3 m. It is desirable to install in. If it is too close, the heat retaining medium 4 enters the inside of the ladle 1 and the temperature inside the ladle 1 falls. On the other hand, if it is too far, the heat retaining medium 4 does not sufficiently form an air curtain, and the inside of the ladle 1 cannot be effectively heat-insulated.

It is desirable that the flow rate Q of the heat retaining medium 4 blown out from the discharge means 2 is 100 m ³ / min ≦ Q ≦ 200 m ³ / min. If the flow rate is too small, a sufficient air curtain effect cannot be obtained. On the other hand, if the flow rate is too large, the amount of entrained air increases, so that the heat retaining medium 4 enters the ladle 1 and the temperature inside the ladle 1 decreases, leading to an increase in cost. .

  Specifically, it is preferable that the heat retaining medium 4 is discharged in the direction opposite to the opening of the molten steel carrying container so that the inclination angle (θ) with respect to the vertical direction is 5 ° ≦ θ ≦ 15 °.

  Actually, as shown in FIGS. 4 and 5, in the side view, the heat retaining medium 4 is discharged with a certain spread. As the inclination angle (θ), an angle formed between the central axis 22 in the heat retaining medium discharge direction and the vertical line 21 can be employed. If the inclination angle is less than 5 °, the heat retaining medium 4 may enter the inside of the ladle 1, and the temperature inside the ladle 1 may be lowered to promote cooling of the refractory. On the other hand, if the inclination angle is larger than 15 °, the heat retaining medium 4 may not sufficiently form an air curtain, and the inside of the ladle 1 may not be effectively heated. The inclination angle (θ) of the heat retaining medium 4 is most preferably 10 °.

  FIG. 4 is a schematic view showing a situation in which a narrow pipe 5 is used as a discharge port of the discharge means 2 and the heat retaining medium 4 is discharged from the narrow pipe 5. A pipe for supplying the heat retaining medium 4 to the narrow pipe 5 is attached to the support means 3 on which the narrow pipe 5 is installed. The heat retaining medium 4 is supplied to each of the plurality of narrow pipes 5 through the piping.

  Alternatively, the support means 3 may be a hollow member, and the heat retaining medium 4 may be supplied to each narrow pipe 5 through the heat retaining medium 4.

  As the narrow mouth pipe 5, a pipe having an inner diameter of 15 mm to 25 mm at a portion where the heat retaining medium blows out can be used. The shape of the pipe is not particularly limited, but may be a straight pipe having a constant inner diameter along the axial direction, or a shape in which the discharge port is tapered toward the tip.

  In FIG. 4, reference numeral 23 denotes a horizontal distance (L1) between the opening surface (opening portion 11) of the molten steel carrying container (here, ladle 1) and the discharge port tip of the narrow pipe 5, and 24 denotes a molten steel carrying container ( Here, it is the vertical distance (L2) between the upper end of the opening 11 of the ladle 1) and the outlet end of the narrow pipe 5.

  FIG. 5 is a schematic diagram showing a heat retaining medium discharge method when the blower 6 is used at the discharge port of the discharge means 2. The blower 6 is a member that sucks ambient gas and discharges it downward, and a fan, blower, or the like is used. The heat retaining medium 4 may be present around the blower 6. Alternatively, a pipe may be installed up to the periphery of the blower 6 and the heat retaining medium 4 may be sent to the periphery of the blower 6 through the pipe. The shape of the blower 6 is not particularly specified.

  Further, as the plurality of discharge means 2 used in one support means 3, both a narrow pipe and a blower may be used. For example, the narrow pipes 5 and the blowers 6 can be alternately provided on one support means 3.

  In addition, the heat-retaining method in the present invention can be applied not only to the molten steel transport container but also to the hot metal transport container. For example, the heat-retaining method of the present invention can be similarly used for a hot metal ladle used to transport hot metal to a converter.

  Furthermore, it is applicable not only to a converter but also to a ladle used in an electric furnace. In addition, it is applicable not only to molten steel and hot metal, but also to the production of non-ferrous metals such as containers for carrying molten metal, such as zinc plating plating tanks, and aluminum and copper.

  Next, a method for measuring the remaining thickness of the molten steel carrying container, which is performed using the above-described heat retaining method for the molten steel carrying container, will be described.

  First, in a state where the molten steel is not charged in the molten steel carrying container, the upper lid attached to the opening is removed when carrying the molten steel carrying container, and the molten steel carrying container is left still with the opening 11 facing sideways. Next, the heat retaining medium 4 is discharged from the discharge means 2 from the front upper part to the lower part of the opening 11 so that the temperature drop index is less than 1. Thereby, a layer of the heat retaining medium 4 is formed in front of the opening 11. As shown in FIGS. 4 and 5, a remaining thickness measuring device 9 is provided on the side opposite to the opening 11 as viewed from the layer of the heat retaining medium 4 (outside the layer of the heat retaining medium 4). The remaining thickness measuring device 9 measures the remaining thickness inside the ladle 1 over the layer of the heat retaining medium 4. As the remaining thickness measuring device 9, for example, an ultrasonic wave propagation meter, a laser distance meter, a 3D laser scanner, or the like that calculates the thickness based on the propagation time of the ultrasonic wave can be used. In addition, the inclination angle of the ladle 1 can also be adjusted as appropriate so that the remaining thickness measuring device 9 can easily measure the remaining thickness inside.

  When the remaining thickness measurement result does not satisfy a certain reference value, repair work such as replacement of the refractory can be performed.

The ladle after discharging the molten steel was turned sideways, and the surface temperature of the refractory at four points in the ladle was measured with a radiation thermometer. As for the size of the ladle, the outer diameter of the opening was about 4.9 m, the outer diameter of the bottom was about 4.5 m, and the height was about 4.5 m. Moreover, the thickness of the refractory used for the ladle was in the range of 150 mm to 400 mm. The temperature measurement positions are 50 cm each from point A to point D shown in FIG. 2 (point A is not shown) in parallel with the ladle axial direction from the upper end, lower end, right end, and left end of the opening. The position was advanced inside the ladle one by one. Air was used as a heat retaining medium. As shown in FIG. 2, six narrow-mouth pipes or discharge fans that discharge air were installed in the upper front part of the opening of the ladle 1. The narrow pipes or discharge fans were installed at equal intervals so that the distance from end to end was about 3 m. The total supply amount of air was 150 m ³ / min, and the total supply amount of air per narrow pipe or discharge fan was 25 m ³ / min. Further, the inner diameter of the discharge port of the narrow pipe was 20.8 mm.

Table 1 below shows a list of conditions and measurement results implemented this time. The average value of the temperatures at the top, bottom, left, and right in the ladle immediately after being turned sideways was defined as the refractory initial temperature T ₀ . The average value of the temperature of the upper, lower, left and right four points in the ladle after 15 minutes from the out ejecting air was refractory temperature T ₁₅ from narrow neck pipe or discharge fans. The inclination angle from the ladle opening of the narrow-mouthed pipe or the discharge fan to the outside was changed in various ways, and the ladle temperature was measured (invention example, comparative example). The ladle temperature was also measured when no air was used (conventional method).

And based on Table 1, the refractory temperature in a ladle was compared with the example of this invention, the comparative example, and the conventional method. Specifically, a temperature drop index indicating the degree of temperature drop on the surface of the refractory when air is discharged (invention example, comparative example) relative to when air is not discharged (conventional method) was used. If the temperature drop index is greater than 1, the temperature inside the ladle tends to drop, and if it is less than 1, the temperature drop is suppressed. As an example, a temperature drop index is calculated for Comparative Example 1. In Comparative Example 1, when calculating the temperature difference between the initial temperature T ₀ and the temperature T ₁₅ after 15 minutes of the refractory becomes 1004-800 = 204 (℃). Further, when the temperature difference is similarly calculated in the conventional method to be compared, 1000−850 = 150 (° C.) is obtained. The temperature drop index in Comparative Example 1 was calculated to be 1.36 by calculating 204/150. FIG. 6 is a graph showing the relationship between the temperature drop index obtained by the same calculation and the inclination angle for Invention Examples 1 to 6 and Comparative Examples 2 to 4.

  As shown in FIG. 6, in the examples in which the inclination angle is in the range of 5 ° ≦ θ ≦ 15 ° (Invention Examples 1 to 6), the temperature drop index is less than 1 and the conventional method does not discharge air. It was confirmed that the temperature drop on the surface of the refractory in the ladle can be suppressed.

  The ladle after discharging the molten steel was turned sideways, and the surface temperature of the refractory at four points in the ladle was measured with a radiation thermometer. As for the size of the ladle, the outer diameter of the opening was about 4.9 m, the outer diameter of the bottom was about 4.5 m, and the height was about 4.5 m. Moreover, the thickness of the refractory used for the ladle was in the range of 150 mm to 400 mm. The temperature measurement positions are 50 cm each from point A to point D shown in FIG. 2 (point A is not shown) in parallel with the ladle axial direction from the upper end, lower end, right end, and left end of the opening. The position was advanced inside the ladle one by one. Air was used as a heat retaining medium. As shown in FIG. 2, six narrow-mouth pipes or discharge fans that discharge air were installed in the upper front part of the opening of the ladle 1. The narrow pipes or discharge fans were installed at equal intervals so that the distance from end to end was about 3 m. Further, the inner diameter of the discharge port of the narrow pipe was 20.8 mm.

Table 2 below shows a list of conditions and measurement results implemented this time. The average value of the temperatures at the top, bottom, left, and right in the ladle immediately after being turned sideways was defined as the refractory initial temperature T ₀ . The average value of the temperature of the upper, lower, left and right four points in the ladle after 15 minutes from the out ejecting air was refractory temperature T ₁₅ from narrow neck pipe or discharge fans. The ladle temperature was measured by changing the flow rate and the installation position of the narrow pipe and discharge fan in various ways (invention example, comparative example). The ladle temperature was also measured when no air was used (conventional method).

  And in Table 2, the refractory temperature in a ladle was compared with the example of this invention, the comparative example, and the conventional method. Specifically, as in Example 1 above, the temperature indicating the degree of temperature drop on the surface of the refractory when air is discharged (invention example, comparative example) versus when air is not discharged (conventional method) The descent index was used. If the temperature drop index is greater than 1, the temperature inside the ladle tends to drop, and if it is less than 1, the temperature drop is suppressed. Table 2 shows the temperature drop index determined by the above calculation for Invention Examples 7-12 and Comparative Examples 5-16.

As shown in Table 2, the air flow rate is in the range of 100 m ³ / min ≦ Q ≦ 200 m ³ / min, and the installation position is in the range of 0.25 m ≦ L1 ≦ 1 m and 0.5 m ≦ L2 ≦ 3 m. In all the examples (Invention Examples 7 to 12), the temperature drop index was less than 1, and it was confirmed that the temperature drop on the surface of the refractory in the ladle could be suppressed as compared with the conventional method in which no air was discharged.

DESCRIPTION OF SYMBOLS 1 Ladle 2 Discharge means 3 Support means 4 Heat retention medium 5 Narrow pipe 6 Blower 7 Heat retention apparatus 9 Remaining thickness measuring device 11 Opening part 21 Vertical line 22 Central axis line 23 in the discharge direction of a heat retention medium Open surface of a molten steel carrying container Distance between the nozzle and the discharge port (L1)
24 Vertical distance (L2) between the upper end of the opening of the molten steel carrying container and the discharge port

Claims (15)

Using a heat retention device having a plurality of discharge means for discharging the heat retention medium and a support means for supporting the discharge means so as to be able to discharge the heat retention medium in the downward direction, the heat retention medium is left to stand horizontally. Discharge means of the heat retaining device is arranged at the front upper part of the opening of the molten metal transport container, and from the discharge means in front of the opening of the molten metal transport container from above to below. A heat retaining method for a molten metal carrying container, wherein the heat retaining medium is discharged to make the following temperature drop index less than 1.
(Temperature drop index) = (Temperature drop on the surface of the refractory inside the molten metal carrying container when the heat retaining medium is discharged) / (Temperature of the surface of the refractory inside the molten metal carrying container when the heat retaining medium is not discharged) Descent amount)   2. The discharge means includes a narrow pipe, and the support means includes a pipe for supplying a heat retaining medium to the narrow pipe, and the heat retaining medium supplied by the pipe is discharged from the narrow pipe. The heat-retaining method for the molten metal carrying container according to 1.   3. The heat retention method for a molten metal carrying container according to claim 1 or 2, wherein the discharge means includes a blower and discharges a heat retaining medium by the blower.   4. The heat retaining medium is discharged in a direction opposite to the opening of the molten metal carrying container so that an inclination angle θ with respect to a vertical direction is 5 ° ≦ θ ≦ 15 °. The heat retention method of the molten metal carrying container as described in any one of the above.   The upper lid provided at the opening of the molten metal carrying container is removed, the molten metal carrying container is tilted sideways, and the heat retaining method for the molten metal carrying container according to any one of claims 1 to 4 is used. The refractory inside the molten metal carrying container is formed by using a residual thickness measuring device installed outside the layer of the heat retaining medium while forming the layer of the heat retaining medium in front of the opening of the molten metal carrying container. A method for measuring a remaining thickness of a molten metal carrying container, characterized by measuring a remaining thickness of the molten metal. A heat retention device having a plurality of ejection means for ejecting a thermal insulation medium and a support means for supporting the ejection means so that the thermal insulation medium can be ejected in a downward direction . Disposing the discharge means on the front upper part of the opening of the molten metal carrying container, and in front of the opening of the molten metal carrying container, the heat retaining medium is transferred from the discharge means from above to below the opening. A heat retention device for a molten metal carrying container, wherein the temperature drop index is less than 1 by discharging .
(Temperature drop index) = (Temperature drop on the surface of the refractory inside the molten metal carrying container when the heat retaining medium is discharged) / (Temperature of the surface of the refractory inside the molten metal carrying container when the heat retaining medium is not discharged) Descent amount) 7. The discharge means includes a narrow pipe, and the support means includes a pipe for supplying a heat retaining medium to the narrow pipe, and discharges the heat retaining medium supplied by the pipe from the narrow pipe. A heat-retaining device for a molten metal carrying container according to 1. The heat retaining device for a molten metal carrying container according to claim 6 or 7, wherein the discharge means includes a blower and discharges a heat retaining medium by the blower . The heat-retaining medium from the claims 6 to the opening of the molten metal transfer vessel in the opposite direction, characterized in that the inclination angle theta with respect to the vertical direction is discharged such that 5 ° ≦ θ ≦ 15 ° 8 The heat retention apparatus for the molten metal carrying container according to any one of the preceding items. 5. The heat retention of the molten metal carrying container according to claim 1, wherein the discharge means has a total discharge flow rate Q of 100 m ³ / min ≦ Q ≦ 200 m ³ / min. Method.   11. The melting according to claim 1, wherein the discharge means has a horizontal distance L1 from the opening surface of the molten metal carrying container of 0.25 m ≦ L1 ≦ 1 m. Heat retention method for metal transport containers.   The discharge means is characterized in that the vertical distance L2 from the upper end of the opening of the molten metal carrying container is 0.5 m ≦ L2 ≦ 3 m, or any one of claims 1 to 4 or 10 and 11 The heat-retaining method of the molten metal conveyance container as described. The heat retention of the molten metal carrying container according to any one of claims 6 to 9, wherein the discharge means has a total discharge flow rate Q of 100 m ³ / min ≦ Q ≦ 200 m ³ / min. apparatus.   The melting according to any one of claims 6 to 9 or 13, wherein the discharge means has a horizontal distance L1 from the opening surface of the molten metal carrying container of 0.25 m ≤ L1 ≤ 1 m. Thermal insulation device for metal transport containers.   The discharge means is characterized in that the vertical distance L2 from the upper end of the opening of the molten metal carrying container is 0.5 m ≦ L2 ≦ 3 m, or any one of claims 6 to 9 or 13 and 14. The heat retention apparatus of the molten metal conveyance container as described.

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