JPH05280Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a heating device for a molten metal injection nozzle used when injecting molten metal.

[Conventional technology]

In continuous casting of molten metal, such as steel, generally the molten steel produced in a steelmaking furnace, such as a converter, is placed in a ladle and transported to the continuous casting machine, and it is difficult to control the injection flow rate because it is poured directly from the ladle. To achieve this, molten steel is stored in a tundish and injected into a continuous casting machine. In the process of obtaining slabs from molten steel, this tundish plays the role of stabilizing the flow of molten steel from the ladle and distributing the molten steel to each strand.At the bottom of the tundish, there is a submerged nozzle that protrudes downward from the bottom, i.e., injects molten metal. A tundish is equipped with a nozzle (hereinafter simply referred to as an injection nozzle), and processes such as flotation of inclusions, which have a great effect on steel quality, are performed in the tundish.

On the other hand, in continuous casting of steel, the casting temperature is required to be within a narrow range, and it is well known that if the temperature is too high than this range, breakout will occur, and if it is too low, nozzle clogging will occur. Therefore, in order to prevent breakout and prevent the nozzle from being blocked due to deposits (alumina, base metal, etc.) on the inner surface of the nozzle, the tundish and injection nozzle are heated to a temperature of 850 to 900℃ before pouring the molten steel. It is heated to. For example, FIG. 1 shows a method in which the tundish and injection nozzle are heated separately. That is, a suitable number of burners 3' are provided on the upper lid 2' of the tundish 1', and the burners burn coke oven gas or the like to heat the inside of the tundish.
On the other hand, an injection nozzle 4' extends downward from the bottom 5' of the tundish. The injection nozzle is heated on the outer periphery, and heat-resistant material (kao wool) is used to prevent heat radiation after the injection is finished.
6' is wound, and the periphery is surrounded by a heat insulating cover 10'. The upper end opening 9' of the injection nozzle was closed with a stopper 8', and the coke oven gas was burned in a burner 11' provided below the injection nozzle to heat the injection nozzle. However, this method generally requires about 120 to 160 minutes for heating, and it has been desired to shorten the heating time. In addition, as another injection nozzle heating method to improve temperature raising efficiency, Japanese Patent Application Laid-Open No. 58-68457
Those shown in the number are known. In this method, the injection nozzle is covered with a heat insulating container and the openings of the tundish, such as the chimney and steel outlet, are closed, and the gas pressure inside the tundish is made into a positive pressure, and the combustion gas, which heats the tundish and raises its temperature, is guided to the injection nozzle. In this method, the injection nozzle and the tundish are heated as one unit. In this method, the heating efficiency decreases unless all the openings of the tundish are closed, so it cannot be used with an open type tundish and has the disadvantage of poor working efficiency.

[Problem that the invention attempts to solve]

This invention solves the conventional drawbacks and problems, improves heating efficiency and work efficiency, shortens the heating process time before steel injection, prevents clogging of the inner surface of the nozzle,
The purpose of this is to eliminate the factors that impede the quality associated with this and also contribute to energy saving.

[Means for solving problems]

This invention solves the conventional problems and achieves the above objectives.The gist of this invention is to insert the injection nozzle of the molten metal container into the heat-insulating container, and use a gas ejector to discharge the high-temperature gas in the molten metal container. In the heating device for the molten metal injection nozzle, which heats the nozzle from both the inside and outside by suctioning from the nozzle, a gas ejector is provided above the heat insulating container, and a temperature sensor is placed further above the gas ejector,
A timer is provided to start counting the heating time upon receiving a heating start signal, and the temperature signal from the temperature sensor and the heating time from the timer are input.
The flow rate of the gas ejector is controlled so that the temperature of the temperature sensor is equal to or higher than the set heating temperature of approximately 900℃ within a predetermined heating time of 60 minutes, and the flow rate of the gas ejector is controlled so that the temperature of the temperature sensor does not exceed 1300℃. A flow rate control circuit for controlling the flow rate of the temperature sensor is provided, and a temperature comparison circuit is provided for inputting the temperature signal from the temperature sensor and comparing the temperature to see if the temperature of the temperature sensor has reached the set heating temperature. An alarm circuit is provided that issues a buzzer or lamp alarm when the comparison result at the set heating time of the timer is that the temperature of the temperature sensor is lower, and furthermore, the temperature rising state of the injection nozzle is monitored at the bottom of the heat insulating container. A heating device for a molten metal injection nozzle is characterized in that it is equipped with an observation window capable of providing a molten metal injection nozzle.

[Effect]

In this device, the high-temperature gas in the molten metal container is sucked through the injection nozzle by a gas ejector installed above the heat-insulating container, and is caused to rise through the periphery of the nozzle, so the injection nozzle is heated from both the inside and outside. In particular, the temperature rise rate is high, and the molten metal container can be worked in the open, so the work efficiency is high. Moreover, since the temperature sensor measures the temperature at a position above the high-temperature gas flow sucked by the gas ejector, accurate temperature measurement is possible. The temperature signal from the temperature sensor is input to a flow rate control circuit and a temperature comparison circuit, and the flow rate control circuit controls the flow rate of the gas ejector so that the set heating temperature is about 900 degrees within a set time of about 60 minutes. Also, if the temperature exceeds the set temperature, the flow rate is controlled so that it does not exceed 1300 degrees. On the other hand, the temperature comparison circuit compares and determines whether the temperature of the temperature sensor reaches the set heating temperature of about 900 degrees. The alarm circuit inputs the comparison result of the comparison circuit and issues an alarm with a buzzer or lamp when the temperature of the temperature sensor does not reach the set temperature within the set heating time from the timer. This can prevent clogging of the nozzle due to incomplete heating.

〔Example〕

The apparatus for implementing the present invention will be explained below based on the drawings.

In this embodiment, the heat-retaining container 2 into which the injection nozzle 1 is inserted has a heat-retaining structure whose inner wall surface is coated with a refractory material such as Kao wool. The injection nozzle 1 is inserted in the axial direction from the top of the container. Although only a portion of the injection nozzle may be housed in the container 2, as shown in a preferred embodiment shown in FIG. may be attached and crimped through a heat insulating material 4 attached to the lower part of the nozzle holder and around the upper opening of the heat insulating container 2. For example, the crimping method is as shown in FIG. The mechanism is such that the heat insulating container can be attached and detached in a short time. Further, a gas ejector 7 is attached to the upper part of the container, and this gas ejector 7 is constructed of a blowing pipe 8, an exhaust pipe 9, and a reducer 10. A temperature sensor 11 is attached to the heat insulating container 2. This temperature sensor 11 is for monitoring and controlling the temperature increase state of the nozzle, and its mechanism will be described below.

As shown in Figure 2, the injection nozzle 1 inserted into the heating device is heated as heating gas passes through the injection nozzle from the tundish, but the heating temperature of the injection nozzle 1 is at least 900°C or higher just before injection of molten metal. It is generally said that it is necessary. Also 900℃
It is best to raise the temperature to within 60 minutes to form an oxidation-preventing film, and maintaining high temperatures above 1300°C should be avoided as this will accelerate the progress of oxidation of the injection nozzle.

For this reason, the control mechanism is
The purpose is to raise the temperature as quickly as possible and to maintain that temperature after the temperature has been raised to a certain level. If the temperature does not rise to a predetermined temperature within a set time, an alarm device is activated.

The most appropriate temperature sensor 11 is a non-contact infrared temperature sensor, but it is also possible to measure the ambient temperature by CA or
A method may also be used in which the temperature of the injection nozzle 1 is estimated by sensing with a PR thermocouple or the like. The reason why the temperature sensor 11 was installed at the top of the heat-insulating container 2 is that as a result of preliminary tests, there is a temperature distribution in the injection nozzle 1, and the difference between the inside of the lower part of the nozzle, where the temperature is highest, and the outer wall of the upper part of the nozzle, where the temperature is the lowest, is approximately 90°C. Problems such as nozzle blockage during the initial stage of molten steel injection due to temperature differences often occur at the top of the nozzle, so by placing it in this position and above the gas ejector 7, the influence of heated gas from the tundish is reduced. This is due to what happened.

12 in Figure 2 is a control device and temperature sensor 1
1 and operates the electromagnetic valve 13-1. The control device 12 includes a flow rate control circuit 20, a temperature comparison circuit 21, a timer 22, and an alarm circuit 23. The alarm circuit 23 receives the time input from the timer 22 and the comparison result input from the temperature comparison circuit 23, and if the predetermined temperature is not reached within a preset time, the alarm circuit 23 will set the temperature to 900°C within 60 minutes from the start of temperature rise.
If the target is not reached, a buzzer or lamp will notify you. 13-2 is a normal valve, and after the injection nozzle 1 reaches the set temperature and the electromagnetic valve 13-1 is closed by a command from the flow control circuit 20, the compressed gas of the gas ejector 7 necessary for maintaining the temperature is released. This is a regulating valve in the bypass circuit provided to allow the flow of water. It is necessary to adjust this valve according to the set temperature. Here, to explain how the injection nozzle 1 is heated by the device shown in FIG. 2, the air cylinder 5, arm 6 and guide 14 are heated.
The insulating material 4 attached in a ring shape to the upper opening of the heat insulating container 2 that rises in the axial direction by the tundish is crimped to the lower part of the nozzle holder 3 attached to the tundish, whereby the injection nozzle 1 is inserted into the heat-insulating container 2. Of course, it is assumed that at this time the heating of the tundish has already started using the heating burner installed above the tundish. Next, by opening the electromagnetic valves 15 and 13-1, compressed gas is blown out from the blowing pipe 8 of the ejector and flows to the exhaust pipe 9. At this time, the heat insulating container 71
A suction force is generated. As a result, the hot gas used for heating the tundish is supplied from the upper opening of the injection nozzle 1, passes through the inside of the nozzle while heating, and is discharged from the lower opening 16, and the hot gas rises along the outer periphery of the nozzle. , is discharged to the outside of the heat insulating container 2 from the exhaust pipe 9 of the ejector section.

When the temperature set by the control device is reached, the electromagnetic valve 13-1 is closed, and the compressed gas passes through the regulating valve 13-2 to supply the amount of compressed gas necessary to maintain the nozzle temperature to the ejector. Further, if the temperature does not reach the set temperature within the time set by the alarm circuit 23, a buzzer or lamp will notify you. When the temperature of the nozzle rises to a predetermined temperature and it is time for the tundish to receive molten steel, the solenoid valve 15 is activated.
is closed, the air cylinder 5 is opened, and the heat insulating container 2 is lowered.

The results of comparing the heating progress of the injection nozzle 1 by the above method with the conventional method are shown in Figure 3. The temperature measurement by the new method is performed in a space 15 mm horizontally away from the top of the nozzle. This value is obtained by measuring the difference from the actual temperature in a preliminary experiment and correcting it in the control device. The old method is the value measured at the same position as the new method. As can be seen from Figure 3, the heating device of this invention can heat the molten metal injection nozzle more quickly and to a higher temperature than the conventional heating device, and can control excessive heating, and the results are remarkable. Figure 2 17 shows an observation window for visually observing the heating state, which allows the injection nozzle 1 to be visually confirmed as red-hot and to be judged more accurately.

[Effect of idea]

As described above, according to the present invention, high-temperature gas can be easily sucked into the molten metal injection nozzle by using compressed gas, and by heating the nozzle from the inner and outer surfaces simultaneously, it is possible to easily draw high-temperature gas into the molten metal injection nozzle. It is possible to achieve uniform high-temperature heating in a short time, which was difficult to achieve with other methods, and it eliminates nozzle clogging during injection, as well as having a significant energy-saving effect. Furthermore, if the set heating lower limit temperature is not reached within a predetermined time, a buzzer or lamp is used to warn you, thereby preventing clogging of the upper nozzle. Furthermore, since the observation window is provided at the bottom, final confirmation can be made even if the temperature sensor is out of order, and it is also effective in preventing overheating of the injection nozzle.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a conventional heating device, Fig. 2 is a front view showing an embodiment of the present invention, Fig. 3 is a graph showing changes in injection nozzle temperature, and Fig. 4 is a circuit of the control device of the embodiment. The block diagram, FIG. 5, is a plan view showing the gas ejector. 1... Injection nozzle, 2... Heat insulating container, 7... Gas ejector, 8... Blowing pipe, 9... Exhaust pipe,
10...Register, 11...Temperature sensor,
12...Control device, 13-1...Solenoid valve, 1
3-2...Adjustment valve, 14...Guide, 15...
... Solenoid valve, 16 ... Lower opening, 17 ... Observation window, 20 ... Flow rate control circuit, 21 ... Temperature comparison circuit, 22 ... Timer, 23 ... Alarm circuit.

Claims (1)

[Scope of utility model registration request] In a heating device for a molten metal injection nozzle, the injection nozzle of the molten metal container is inserted into a heat insulating container, and the high temperature gas in the molten metal container is sucked from the nozzle using a gas ejector to heat the nozzle from both the inside and outside. A gas ejector is placed above the heat insulating container, a temperature sensor is placed above the gas ejector, and a timer is provided which starts counting the heating time upon receiving the heating start signal, and the temperature signal from the temperature sensor and the timer are provided. By inputting the heating time from the timer, the flow rate of the gas ejector is controlled so that the temperature of the temperature sensor reaches the set heating temperature of approximately 900℃ within a predetermined heating time of 60 minutes, and after that, the temperature of the temperature sensor is A flow rate control circuit is provided to control the flow rate of the gas ejector so that the temperature does not exceed 1300℃, and a temperature signal is input from the temperature sensor to check whether the temperature of the temperature sensor has reached the set heating temperature. A temperature comparison circuit is provided, and an alarm circuit is provided to issue a buzzer or lamp alarm when the comparison result of the temperature comparison circuit's timer during the preset heating time is that the temperature of the temperature sensor is lower. A heating device for a molten metal injection nozzle, characterized in that it is equipped with an observation window that can monitor the temperature rising state of the injection nozzle.