JPH01262052A - Method for preventing over-heating of molten steel in tundish heater - Google Patents

Abstract

PURPOSE:To stably prevent over-heat of molten steel in inner part of a heater by inserting a temp. sensor in the crucible style induction heating type heater providing a tundish, continuously measuring the molten steel temp. near the bottom part of the heater and controlling the measured value so as to become the specific value. CONSTITUTION:The crucible style induction heating type heater 2 is connected and communicated with side part near the bottom part of the tundish 1 and refractory tube 5 is inserted in the bottom part of the heater 2 through refractory material 4. The temp. sensor A composing of thermocouple is arranged at the tip of the refractory tube 5 and the molten steel poured in the tundish 1 is continuously cast while heating with the heater 2. Then, the molten steel temp. near the bottom part in the heater is measured with the temp. sensor A and the input power to the heater is automatically controlled with a power control device 6 so that the measured temp. comes to <=1,600 deg.C. By this method, erosion of the refractory in this heater 2 is effectively restrained and the molten steel in the tundish 1 is suitably prevented from flowing-out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for appropriately preventing overheating of molten steel inside the heater in continuous casting using a tundish equipped with a crucible-type induction heater.

[Conventional technology and its problems]

Conventionally, in continuous casting, the problem of molten steel flowing out due to erosion of refractories in the tundish can be solved by managing the refractories in consideration of the lifespan of the refractories, since the maximum temperature of the molten steel injected into the tundish is around 1570°C. .

There were no particular problems.

However, recently, in order to control the temperature of the molten steel inside the tundish, tundishes equipped with crucible-type induction heaters are often used. The temperature of the molten steel in the heater may rise extremely, causing problems such as molten steel flowing out due to melting of the refractories.

Therefore, in order to detect the melting of the refractory in advance and avoid the above-mentioned trouble, a temperature sensor is set on the back side of the refractory inside the heater or on the iron wall of the heater to detect the temperature rise, and based on this, the heater A method of controlling heating by

However, in such a method, the refractory is often already severely melted and damaged by the time a temperature rise is detected, and there is a drawback that melting loss cannot be reliably avoided.

The present invention was made in view of such conventional problems,
It is an object of the present invention to provide a method that can appropriately prevent overheating of molten steel within a heater.

[Means to solve the problem]

For this reason, the present invention focuses on the fact that the temperature of molten steel in a crucible-type heater is most likely to rise near the bottom of the heater, where insufficient reflux is most likely to occur. Its basic feature is that the temperature of molten steel near the bottom of the heater is continuously measured by a sensor, and the power input to the heater is controlled so that the measured value is 1600° C. or less.

Hereinafter, details of the present invention will be explained based on the drawings.

FIG. 1 shows the bottom structure of a tundish equipped with a crucible-type induction heating heater. (1) is the tundish main body, (2) is a crucible-type induction heating heater, and the heater is It is connected to the side near the bottom of the tanditsu, and its internal space communicates with the interior of the tanditsu. This heater (2) has an induction coil (3) inside its refractory material (4). At the bottom of the heater (2),
Refractory pipe (5) (protective pipe) penetrates the refractory material (4)
is inserted, and a temperature sensor (A) consisting of a thermocouple is provided at the tip inside the refractory pipe (5).

The molten steel injected into the Kundeitshu (1) is heated by the heater (
2), the molten steel is continuously cast while being heated at zero, but in the present invention, the molten steel temperature near the inner bottom of the heater is continuously measured by the temperature sensor (A), and the temperature is adjusted so that the measured temperature is 1600°C or less. The power control device (6) automatically controls the power input to the heater (PII automatic control, etc.).

In the present invention, the location where the molten steel temperature is measured by the temperature sensor is limited to the vicinity of the bottom of the heater. This is because, as mentioned above, the bottom of the heater is the part where the temperature is most likely to rise due to insufficient reflux of molten steel, and even if heating control is performed based on the measured temperature of other parts, there is a risk of overheating at the bottom of the heater. .

In addition, the present inventor has confirmed through practice that it has been found that melting damage to durable materials can be effectively prevented by suppressing the temperature of molten steel in the heater to 1600° C. or less. Figure 2 shows the relationship between the temperature of the molten steel in the heater and the number of times the refractory in the heater is used.When the molten steel temperature exceeds 1600°C, the life of the refractory rapidly decreases due to melting damage. I understand. Therefore, in the present invention, the upper limit of the molten steel temperature is set at 1600°C, and heating control of the heater is performed so that the measured temperature is 1600°C or less.

Note that the temperature sensor (A) is installed by installing a refractory pipe (
5), or a structure in which a plug equipped with a refractory pipe (5) is inserted into the attachment hole of the refractory material (4), or the like may be used as appropriate.

〔Example〕

In a tundish (capacity s ton ) having a heater with a structure as shown in Fig. 1, a thermocouple is inserted into the bottom of the heater through a refractory tube, and the heater power is set to a maximum of 500K.
w, and the heater power is P based on the temperature measured by the thermocouple.
The present invention was implemented through ID control. At this time, it was possible to heat the molten steel in the tundish at a temperature of 2.0°C/n1ln.

As a result of implementing the method of the present invention, as shown in Table 11, the life of the refractories, that is, the processing time of molten steel, could be greatly improved. In contrast, with conventional methods, when the temperature of molten steel inside the heater rises due to fluctuations in operating conditions, the temperature sensor attached to the heater iron wall cannot detect the temperature change, and during this time the refractory is severely eroded.* Temperature Measurement Implementation Method (Thermocouple Installation) [Effects of the Invention] According to the present invention described above, it is possible to effectively suppress the melting of the refractory in the heater and appropriately prevent the trouble of molten steel flowing out in the tundish. I can do it.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an apparatus to be used for carrying out the present invention. FIG. 2 shows the influence of the temperature of molten steel in the heater on the life of the refractory in the heater. In the figure, (1) shows a tundish, (2) a heater, (5) a refractory pipe, (6) a power control device, and (A) a temperature sensor. Patent applicant: Nippon Kokan Co., Ltd. Higashi Enki Co., Ltd.
Kitashiba Electric Co., Ltd. Inventor Takashi Yamaguchi
Miyahara quick turn
Sen Shido Matsumura
Yamamura twist
Tsuruga Hall
Shin Miyajima - same
Susumu Ishihara, Attorney, Sho Yoshihara, Patent Attorney, Masatoshi Tomachi

Claims (1)

[Claims] When performing continuous casting using a tundish equipped with a crucible-type induction heater, the temperature of the molten steel near the bottom of the heater is continuously measured by a temperature sensor inserted into the heater through a refractory tube. A method for preventing overheating of molten steel in a tundish heater, characterized by controlling the power input to the heater so that the temperature becomes 1600°C or less.