JP4712513B2 - Tundish maintenance equipment - Google Patents

Description

The present invention relates to a tundish maintenance device after continuous casting is completed.

The tundish for which continuous casting has been completed is used for performing continuous casting again after removing the remaining steel slag in the tundish and performing maintenance.
In addition, when removing the remaining steel iron in the tundish, if the remaining steel iron is not sufficiently cooled, the remaining steel iron shrinks insufficiently and the remaining steel iron adheres to the tundish. It is necessary to carry out the removal work of the remaining steel slag. Thus, when removing the remaining steel slag with a machine, the refractory of the tundish is easily damaged, and it takes time to repair the damaged part. In addition, since a large amount of repair material is used for the damaged part, the repair material cost is high and it is not economical, and when the casting is performed again using this tundish, if the repair material does not have sufficient drying time, the repair material A large amount of volatile components evaporate, causing troubles such as refractory damage.
On the other hand, when the remaining steel slag is cooled by spraying a large amount of cooling water (spray) on the remaining steel slag in the tundish, the cooling water does not evaporate and stays in the tundish, and the water remains in the tundish fireproof. Infiltrate objects. For this reason, when performing casting again using this tundish, a large amount of water infiltrated into the refractory material evaporates, causing a problem that the refractory material is damaged, for example.

For this reason, conventionally, after adjusting the amount of water sprayed to the remaining steel plate in the tundish as appropriate and cooling the remaining steel plate using a machine, for example, the maintenance method disclosed in Patent Document 1 is used. As described above, the tundish refractory is cooled by spraying 0.5 to 3.5 L (liter) of water per minute using an axial fan, and the tundish is maintained.
Patent Document 2 discloses a method of maintaining a tundish by suspending an axial fan with a swivel arm installed in the vicinity of the tundish and cooling the refractory of the tundish.

JP-A 61-159251 Japanese Utility Model Publication No. 3-57460

However, any of the above-described methods relates to a method for cooling a refractory in a tundish, and does not propose a method for cooling and removing a remaining steel plate in a tundish after continuous casting. If the remaining steel plate in the tundish is cooled using an axial fan and a small amount of water, the temperature of the remaining steel plate cannot be reduced sufficiently in a short time, and time is required for maintenance of the tundish. Cost. For this reason, in order to sufficiently cool the remaining steel plate in the tundish, it is necessary to cool the remaining steel plate for a long time, but in this case, the maintenance time of the tundish becomes long and workability is poor. In order to allow the remaining steel plate to be cooled for a long time, for example, it is possible to increase the number of installed axial fans, but in this case, capital investment is required as the number of installed tundishes increases. There is also a problem.

The present invention has been made in view of such circumstances, and a tundish maintenance device capable of simplifying the removal work of the remaining steel iron from the tundish, improving workability, and shortening the removal work. The purpose is to provide.

The tundish maintenance device according to the present invention that meets the above object has a plurality of air-water nozzles capable of spraying air-water mixed with water and air in a tundish having a high-temperature residual steel rod at the bottom, The amount of steam blown from each steam nozzle is individually controllable, and further, a mechanism for inverting the tundish is provided, and the tundish is reversed by the mechanism, from each steam nozzle. The remaining steel plate solidified by spraying is removed.

In the tundish maintenance device according to the present invention, each of the air-water nozzles is disposed above the tundish, and is provided in a dust collection hood provided with an intake port capable of sucking steam generated from the tundish. Preferably it is.
In the tundish maintenance device according to the present invention, the installation height of the air-water nozzle is set to H as the distance from the surface of the remaining steel plate at the bottom of the tundish to the jet outlet position of the air-water nozzle, When the distance from the surface of the remaining steel plate to the upper end position of the tundish is h, the ratio of H / h is preferably 2.5 or more.

The tundish maintenance device according to claims 1 to 3 , in which air and water mixed with water and air are blown into the tundish in a state where the bottom of the tundish has a high-temperature steel residue, so that only water is blown. As in the case, it is difficult to form a vapor film on the surface of the remaining steel sheet, and it is possible to cool the remaining steel sheet by suppressing the retention of water on the vapor film. As a result, the remaining steel sheet can be cooled and solidified to a lower temperature in a shorter time than before, so the removal work of the remaining steel sheet from the tundish can be simplified, the workability is improved, and The time required can be shortened and work efficiency can be improved.

Since the maintenance device of the tundish according to claims 1 to 3 can individually control the amount of air blown from the plurality of air-water nozzles to the remaining steel slag for each steam water nozzle, for example, the remaining steel slag in the tundish The amount of air and water can be easily adjusted according to the amount of water.
In particular, since the tundish maintenance device according to claim 2 is installed in a dust collection hood having an intake port capable of sucking steam, the maintenance device can be manufactured without making a large capital investment. It is.
The tundish maintenance device according to claim 3 defines the installation height of the air-water nozzle with respect to the remaining steel slag. For example, the air-water nozzle caused by steam or dust generated when air is blown into the tundish It is possible to continuously spray the water while preventing the nozzle from being clogged and suppressing the damage to the water nozzle.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1 is an explanatory view of a maintenance method using a tundish maintenance device according to an embodiment of the present invention, and FIGS. 2 (A) and 2 (B) are views of air blown from a steam nozzle to a remaining steel slag. FIG. 3 is an explanatory diagram for examining the height position of the steam nozzle for spraying steam, and FIG. 4 is a diagram for explaining a tundish maintenance method according to a modification. .

As shown in FIG. 1, the maintenance method using the tundish maintenance device according to the embodiment of the present invention is in a state where there is a high-temperature remaining steel rod 12 at the bottom 11 of the tundish 10 where continuous casting is completed. In this method, air and water 13 in which water and air are mixed are sprayed into the tundish 10, and the remaining steel slag 12 is cooled and solidified to be removed. The tundish 10 is prepared by sequentially performing a primary cooling process, a secondary cooling process, a bare metal removing process, a dismantling process, and a tertiary cooling process. This will be described in detail below.

First, after transporting the tundish 10 for which continuous casting has been completed to a residual steel slag removal work place (not shown), it is processed in a primary cooling step.
In this primary cooling step, cooling water (also referred to as spray water) is sprayed into the tundish 10 where the continuous casting has been completed. For example, the remaining steel rod 12 in the tundish 10 is removed and the sliding nozzle device is removed. This is a step of reducing the temperature in the tundish 10 (for example, about 800 ° C.) to a temperature at which it can be performed.
The tundish 10 has a capacity capable of storing molten steel of 10 tons or more (here, 30 tons), and an upper limit value is not specified, but there are currently about 50 tons. Further, the amount of the remaining steel iron 12 in the tundish 10 is 1% by volume or more and 20% by volume or less (here, 3 tons) of the capacity of the tundish 10, preferably the lower limit is 5% by volume and the upper limit is 15% by volume. is there.

In this way, the tundish 10 that has been subjected to the primary cooling process is processed in the secondary cooling process.
In this secondary cooling step, the remaining steel slag 12 is cooled using a plurality (six in this case) of steam-water nozzles 14 that eject the steam-water 13 in which water and air are mixed. The plurality of air-water nozzles 14 are provided on a dust collection hood 15 that is rotatable and can be disposed above the tundish 10, and is attached to the surface of the dust collection hood 15 facing the tundish 10. Yes. In addition, the air / water nozzle 14 is configured to be able to spray air / water around an axial center of the air / water nozzle 14 within an angle range of, for example, 10 degrees to 90 degrees. An air inlet 16 that can suck the steam generated from the tundish 10 is also provided on the surface of the dust hood 15 facing the tundish 10.
Thus, the dust collection hood 15 provided with the plurality of air-water nozzles 14 and the intake ports 16 constitutes a tundish maintenance device 17.

The dust collection hood 15 of the tundish maintenance device 17 is rotated so that the air-water nozzle 14 is positioned above the tundish 10, and the remaining steel rod 12 in the tundish 10 is directed from the air-water nozzle 14. By blowing the steam water 13, unlike the case of spraying only water, the remaining steel rod 12 is cooled (for example, about 400 ° C. or less) while suppressing the formation of a vapor film on the surface of the remaining steel rod 12. Solidify. For this reason, there is no cooling hindrance due to the vapor film, and the cooling rate of the remaining steel rod 12 can be increased as compared with the case where only water is sprayed.
Then, after removing the dust collecting hood 15 from above the tundish 10 in the metal extraction process, the tundish 10 is turned upside down and solidified by inserting the bar 19 from the discharge port 18 for discharging molten steel. Remove the remaining steel bar 12.

In the dismantling process, after the tundish 10 turned upside down is returned to its original state, the residual metal attached to the surface of the refractory of the tundish 10 and the coating layer (for example, formed by previously applying to the surface of the refractory) The machine (mainly magnesia) is removed by using a machine (a chiseling machine) 20.
In the tertiary cooling step, the dust collection hood 15 is disposed above the tundish 10, and the water 21 is blown into the tundish 10, thereby reducing the temperature of the refractory (for example, about 200 ° C. or less, preferably 150 ° C. or lower). Further, after the repair material is arranged at the damaged portion of the refractory, a coating material is applied to the entire surface of the refractory to form a coating layer. In addition, the steam water 21 used in the tertiary cooling step can be the same as the steam water 13 used in the secondary cooling step.
After the tundish 10 prepared by the above method is installed again in a continuous casting facility (not shown), the refractory of the tundish 10 is heated in advance and molten steel is supplied to perform continuous casting.

The amount of water used for the air 13 in the secondary cooling step is 1 liter / minute to 5 liters / minute per ton of the tundish 10 (here, the capacity of the tundish 10 is 30 tons, The amount of water is 30 liters / minute or more and 150 liters / minute or less).
Here, when the amount of water is less than 1 liter / minute per ton of tundish, the amount of water becomes too small, and it takes a long time to cool the remaining steel plate, resulting in poor workability. On the other hand, when the amount of water exceeds 5 liters / minute, the amount of water becomes too large, and a vapor film is easily formed on the surface of the remaining steel plate, so that the remaining steel plate cannot be cooled in a short time.
For this reason, the lower limit of the amount of water used for air is 1 liter / minute per ton of tundish, but it is preferably 1.5 liter / minute, and the upper limit is 5 liter / minute. It is preferably 4 liters / minute, more preferably 3 liters / minute.

The amount of air in the water 13 (air / water ratio) is 50 liters to 200 liters per liter (kg) of water used. Air is a compression pump (not shown) (for example, a pressure of 5 kg / cm ²
Degree).
Here, when the amount of air in the air is less than 50 liters per liter of water to be used, the amount of air in the air is too small, and the above-described effect when using air is reduced. In addition, when the amount of air in the air exceeds 200 liters per liter of water used, the amount of air in the air is too large, and the cooling effect of the remaining steel slag with water becomes worse.
For this reason, the lower limit of the amount of air in the air is 50 liters per liter of water used, but 60 liters is preferable, and the upper limit is 200 liters, but 150 liters, and even 100 liters. Is preferred.

This spraying of the steam 13 is performed on the bottom 11 in the tundish 10 and also on the lower side of the side wall. Here, the spraying range of the steam 13 will be described with reference to FIGS. 2 (A) and 2 (B).
The capacity of the tundish used was 30 tons, the amount of steel remaining in the tundish was 2 tons, the amount of water used for air was 60 liters / minute, and the amount of air in the air was 83 liters per liter of water. is there. Moreover, the horizontal axis of FIG. 2 (B) is the case where the width of the surface of the remaining steel slag at the bottom of the tundish is W1, and air is blown from the water nozzle outside the tundish (that is, in a free state). Shows the ratio of W2 / W1 when the width of the air that can be sprayed is W2, and the vertical axis shows the temperature of the remaining steel slag and the inside of the tundish of the solidified steel slag (bullion and slag) The removal rate is shown. This air-water spraying range was set by changing the height position of the air-water nozzle with respect to the surface of the remaining steel plate. The temperature of the remaining steel plate is measured by arranging thermocouples on the front surface side (d1) and the back surface side (d2) of the remaining steel plate. In this case, the surface side of the remaining steel plate refers to the upper surface side of the remaining steel plate taken out in an inverted state in the metal blanking step, and the back surface side refers to the lower surface side.

As is clear from FIG. 2, the ratio of W2 / W1 is increased, that is, by increasing the width W2 that can be blown with respect to the width W1 of the surface of the remaining steel sheet, the temperature on the front side and the back side of the remaining steel sheet is increased. It can be seen that the difference becomes smaller. It can also be seen that the removal rate of the metal increases as the temperature difference decreases.
In particular, by setting the ratio of W2 / W1 to 1.4 or more, the remaining steel sheet can be uniformly cooled, and at the same time, the coating layer formed on the side wall of the tundish can be cooled. Thus, by cooling the coating layer, a large number of microcracks are formed in the coating layer, and the solidified steel plate can be easily peeled off when the tundish is turned upside down.
Note that the upper limit value of the ratio of W2 / W1 is not specified because it is sufficient that air can be sprayed at least at the bottom and the lower side of the side wall in the tundish. There is no problem as long as you can spray the whole area.

As shown in FIG. 3, the installation height of the air-water nozzle 14 is set such that the distance from the surface of the remaining steel rod 12 at the bottom 11 of the tundish 10 to the jet outlet position of the air-water nozzle 14 is H. When the distance from the surface of the ridge 12 to the upper end position of the tundish 10 is h, the H / h ratio is set to 2.5 or more.
Here, when the ratio of H / h is less than 2.5, the distance H from the surface of the remaining steel slag to the spout nozzle position of the steam-water nozzle is shortened, and steam generated by blowing steam to the remaining steel slag In addition, there is a possibility that the nozzle of the water nozzle is clogged by the dust and the water nozzle itself is damaged.
On the other hand, if the ratio of H / h is increased, that is, if the installation height of the air-water nozzle is increased, the steam and dust generated by the air-water spray diffuse to the surroundings without being collected by the dust collection hood. In order to enhance the function of the dust collection hood, the H / h ratio is set to about 4 or less, preferably 3.5 or less.

Further, the tundish is not only flat at the bottom, but as shown in FIG. 4, the tundish 22 inclined downward from the long nozzle side to which the molten steel is supplied to the stopper side for discharging the molten steel. There is also. When the steam 24 is sprayed onto the remaining steel rod 23 of the tundish 22, the amount of the steam 24 sprayed from each of the steam nozzles 14 to the remaining steel rod 23 is set to the remaining steel rod 23 in the tundish 22. Adjust according to the amount. Specifically, the amount of remaining steel on the long nozzle side and the stopper side in the tundish 22 increases as the thickness of the remaining steel plate increases. The amount of water sprayed is set to be larger than the amount of water sprayed on the long nozzle side where the remaining steel slag is thin.
As shown in FIG. 4, the adjustment of the amount of sprayed water is made by dividing the water supply pipe 25 for supplying water to the plurality of water nozzles 14 into the long nozzle side and the stopper side, and supplying each water supply branch pipe 26, 27. The opening / closing time or the opening / closing amount of the opening / closing valves 28 and 29 provided in the control valve is also controlled (also referred to as width cut control), and the amount of steam sprayed from each steam nozzle 14 is individually controlled.

Next, examples carried out for confirming the effects of the present invention will be described.
First, with regard to the maintenance time of the tundish, the case where air is sprayed with the remaining steel slag remaining in the tundish is an example, and the case where water is sprayed on the remaining steel slag in the tundish is a conventional example. This will be described with reference to FIG. In FIG. 5, the temperature in the tundish was measured with a thermocouple embedded in the back surface of the coating layer.
Moreover, the volume of the molten steel of the tundish used was 30 tons, and in the example, in the state where 2 tons of residual steel slag was present in this tundish, the water (water volume: 60 liters / minute, the air-water ratio: 83 As a result of spraying (liter / kg), the conventional example is a result of spraying water (water amount: 60 liter / min) to the remaining steel slag in the tundish.

In the embodiment, after the tundish that has been continuously cast has been transported to the remaining steel slag removal work place (not shown), cooling water (spray) is sprayed in the primary cooling step to lower the temperature in the tundish to 840 ° C. It was.
Next, air was blown into the tundish in the secondary cooling step, and the temperature in the tundish was lowered to 400 ° C., and then a metal extraction process and a dismantling process were performed. This lowered the temperature in the tundish to 280 ° C.
Then, in order to repair the tundish refractory and apply the coating material to the surface of the refractory, after the air is blown into the tundish in the tertiary cooling step, the temperature in the tundish is lowered to 150 ° C. Then, air was blown into the tundish (blower cooling), and the temperature in the tundish was lowered to 100 ° C.
By performing the tundish maintenance according to the above procedure, it took about 8 hours from the end of casting to the end of maintenance.

On the other hand, in the conventional example, after the tundish that has been continuously cast has been transported to the remaining steel slag removing work place (not shown), the cooling water was sprayed in the primary cooling step to lower the temperature in the tundish to 840 ° C. .
Next, although the bullion extraction process and the dismantling process were performed, since the secondary cooling process was not performed as in the example, the temperature in the tundish at the start of the bullion extraction process was 840 ° C. The temperature in the tundish at the end of the dismantling process was 580 ° C. For this reason, air was blown into the tundish after completion of the dismantling process, but the temperature in the tundish could only be reduced to 270 ° C., and the refractory surface of the tundish was repaired and the surface of the refractory compared to the embodiment. It took time to apply the coating material.
It took 13 hours or more from the end of casting to the end of maintenance by maintaining the tundish according to the above procedure.
From this, it has been confirmed that by applying the present invention, it is possible to simplify the removal work of the remaining steel sheet from the tundish, improve the workability, and shorten the removal work.

Subsequently, using the tundish (30 tons of molten steel) after 50 hours of casting was completed, the tundish maintenance time, tundish maintenance load, boil generation, and refractory costs were examined for each cooling condition. The results will be described with reference to Table 1. In addition, cooling of the remaining steel slag was performed in a state where 2 tons of residual steel slag was previously present in the tundish.
Here, each examination item is based on the case where the remaining steel plate is cooled using only water (1 in this case), and the result of using air and water is expressed as an index. This tundish maintenance time index is the primary cooling process, secondary cooling process, metal blanking process, dismantling process, tertiary cooling process, repair of tundish refractories, The total time of applying the coating material to the refractory surface is expressed as an index. In addition, the tundish maintenance load index represents the total time of the bullion removal process, the dismantling process, and the repair of the tundish refractory in the above time. The boil generation index is an index indicating the frequency of troubles in which a large amount of water infiltrated into the refractory material evaporates and the refractory material is damaged, for example. Furthermore, the refractory cost index is an index representing the amount of repair material used to repair a damaged part of the refractory.

As is clear from Comparative Example and Example 2 where the amount of water used is the same, it is possible to compare the tundish maintenance time, tundish maintenance load, boil generation, and refractory costs by using air. Better results than the examples were obtained.
In addition, Example 1 in which the amount of water and the amount of air were reduced at the same air-water ratio as Example 2 gave better results than the comparative example except for the tundish maintenance time. On the other hand, in Example 3 in which the amount of water and the amount of air were increased, better results were obtained than in the comparative example except for the occurrence of boil.
And Example 4 which reduced the air-water ratio with the same amount of water as Example 2 obtained a better result than the comparative example except for the occurrence of boil. On the other hand, Example 5 with an increased air / water ratio gave better results than the comparative example except for the tundish maintenance time.
In addition, about Examples 1-5, the removal operation | work of the remaining steel iron from the inside of a tundish could be simplified and the workability | operativity was made favorable.
From the above, it was confirmed that the maintenance work of the tundish becomes better than before by using the air to cool the remaining steel slag and adjusting the amount of water or the air / water ratio to be used.

Furthermore, the result of having examined the boil generation | occurrence | production and the tundish preform | base_material repair amount by controlling the amount of blown air according to the amount of remaining steel irons is demonstrated, referring FIG. 6 (A) and (B). Here, a tundish with a molten steel capacity of 30 tons was used, the amount of remaining steel iron was 2 tons, the thickness of the remaining steel iron on the long nozzle side was 50 mm, and the thickness of the remaining steel iron on the stopper side was 100 mm. In the state, steam was sprayed (see FIG. 4).
In addition, boil generation and tundish base material repair amount are based on the case where air and water are sprayed evenly and uniformly in the tundish (here, 1), and control of the amount of air sprayed without taking into account the amount of steel remaining (When there is width cutting control) and when the amount of blown water control shown in Fig. 6 (B) is performed according to the thickness of the remaining steel plate (with width cutting control, with remaining steel plate control) It is a result.
Here, the width cutting control is a method of controlling the water injection amount according to the cooling area on the stopper side and the long nozzle side in the tundish (increasing the water injection amount as the cooling area increases). is there. Further, the remaining steel rod control is a method of controlling the water injection time on the stopper side and the long nozzle side in accordance with the remaining steel rod amount in addition to the above-described width cutting control.
In the case of this width control, water is blown on the stopper side for 36 minutes with a water volume of 36 liters / minute and an air / water ratio of 83 liters / kg, and the water volume is 24 liters / minute on the long nozzle side. Was controlled to spray 83 l / kg of air and water for 10 minutes. In addition, when the width control is performed and the remaining steel rod control is performed, the water amount of 36 liters / minute and the air / water ratio of 83 liters / kg are sprayed on the stopper side for 12 minutes, and the water amount is 24 liters on the long nozzle side. Control was performed by blowing air for 8 minutes at an air / water ratio of 83 liter / kg.

As apparent from FIG. 6 (A), by performing the width cut control, the boil generation index was reduced by half compared to the reference, and the tundish base material repair index could be reduced to 0.7. Furthermore, by controlling the blowing time of air and water according to the amount of steel remaining, the boil generation index is reduced to 0.1 compared to the standard, and the tundish base material repair index is also reduced to 0.2 or less. did it.
From the above, using tidal water to cool the remaining steel slag and adjusting the amount of sprayed air according to the amount of remaining steel slag improves the tundish maintenance work than before. I was able to confirm that.

As described above, the present invention has been described with reference to one embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and is described in the claims. Other embodiments and modifications conceivable within the scope of the above are also included. For example, a case where the tundish maintenance device of the present invention is configured by combining a part or all of the above-described embodiments and modifications is also included in the scope of the right of the present invention.
Moreover, in the said embodiment, although the case where the remaining steel slag in a tundish was cooled using several air-water nozzles was demonstrated, the magnitude | size of the tundish which blows air-water, or an air-water nozzle, for example It is also possible to use one air-water nozzle according to the range in which air-water can be ejected.

It is explanatory drawing of the maintenance method using the maintenance apparatus of the tundish which concerns on one embodiment of this invention. (A), (B) is explanatory drawing which shows the influence of the spray width of the steam water sprayed on the remaining steel iron, respectively from the steam water nozzle. It is explanatory drawing at the time of examining the height position of the steam nozzle which sprays steam. It is explanatory drawing of the maintenance method of the tundish which concerns on a modification. It is explanatory drawing of the maintenance method of the tundish which concerns on an Example. (A) is explanatory drawing which shows the influence of the spraying method of the air on the damage of a tundish, (B) is the adjustment method of the spraying time of the water in the case of (A) width cutting control and the remaining steel rod control It is explanatory drawing which shows.

Explanation of symbols

10: Tundish, 11: Bottom, 12: Residual steel slag, 13: Air, 14: Air nozzle, 15: Dust collection hood, 16: Inlet, 17: Tundish maintenance device, 18: Discharge 19: Bar material, 20: Machine, 21: Air and water, 22: Tundish, 23: Residual steel slag, 24: Air and water, 25: Water supply pipe, 26, 27: Water supply branch pipe, 28, 29: Open / close valve

Claims (3)

In the tundish that has a hot steel slag at the bottom, it has multiple water nozzles that can spray water mixed with water and air, and the amount of water sprayed from each water nozzle can be controlled individually. Further, a mechanism for reversing the tundish is provided, the tundish is reversed by the mechanism, and the remaining steel sheet solidified by spraying from each of the water-water nozzles is removed. Tundish maintenance equipment. 2. The tundish maintenance device according to claim 1 , wherein each of the water-and-water nozzles is provided in a dust collection hood that is disposed above the tundish and includes an intake port capable of sucking steam generated from the tundish. A tundish maintenance device characterized by The tundish maintenance device according to claim 1 or 2 , wherein the installation height of the air-water nozzle is a distance from a surface of the remaining steel slag at the bottom of the tundish to a jet outlet position of the air-water nozzle. A tundish maintenance device, wherein a ratio of H / h is 2.5 or more, where H is a distance from the surface of the remaining steel plate to the upper end position of the tundish.

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