JPH01205020A - Method for operating steel manufacturing furnace - Google Patents

Abstract

PURPOSE:To simply reflect effect of ladle heating to decision of steel-tapping temp. by predicting molten steel heat capacity conducted to ladle refractory based on temp. of the ladle refractory assumed from heating atmospheric temp. of the ladle and correcting the steel-tapping temp. from steel manufacturing furnace. CONSTITUTION:Just before steel-tapping from the steel manufacturing furnace (does not show in the figure), the ladle 1 just before receiving the steel is heated to the prescribed temp. by burning fuel with a burner 2, in order to hold the molten steel temp. to sufficiently high. Then, the heating atmospheric temp. T1 of the ladle 1 with a thermocouple 5 or combustion exhaust temp. T3 with a thermocouple 6 arranged at exhausting cylinder 3, is measured. By this mea sured value, the surface temp. T2 of the lade refractory 7 is approximately assumed. Further, based on characteristic of the ladle refractory 7 with this surface temp. T2, the heat content of the ladle, that is, the molten steel heat capacity conducted to the ladle refractory 7 after steel-tapping is predicted. By this conducted heat capacity, temp. descending rate of the molten stele in the ladle 1 can be predicted and the steel-tapping temp. is corrected based on this.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for operating a steelmaking furnace in which steel is tapped from a converter or the like into a heated ladle immediately before receiving steel in a steelmaking process.

[Prior art]

The ladle that receives the molten steel from the converter and injects it into each mold is heated immediately before receiving the molten steel because it is necessary to maintain the molten steel temperature sufficiently high.

Conventionally, as shown in JP-A-51-95934, for example, attention has been paid only to the heating temperature reached by the ladle lining (refractory), and the heating temperature reached is, for example, the lining surface temperature 800. If it is below 800°C, the temperature of the molten steel contained in the ladle will drop significantly, making it difficult to expect stable operation in the next process. That is, in the past, it was preferable to heat the material to as high a temperature as possible.

[Problems to be solved by this invention]

However, such conventional technology has the following problems. That is, 135 due to recent oxygen-enriched combustion.
In ladle heating that can raise the temperature to about 0°C to 1400"C, we not only simply heat it to 800"C or more, but also predict the heat transfer effect due to that heating, that is, the drop in the temperature of the molten steel in the ladle. It is strongly desired to lower the tapping temperature to the necessary minimum based on this prediction. This is because the tapping temperature is directly linked to the steelmaking yield, and the steelmaking costs such as the unit consumption of refractories and solvents.

In the conventional technology, such a reflection on the tapping temperature is not taken into account, so the effect of high temperature heating cannot be fully utilized.

This invention was proposed in view of the above circumstances, and its purpose is to provide a method for operating a steelmaking furnace in which the effect of ladle heating can be fully reflected in the determination of tapping temperature in a simple manner. be.

[Means to solve the problem]

The steelmaking furnace operating method of the present invention measures the heating atmosphere temperature or combustion exhaust gas temperature in which heating is performed immediately before tapping the steelmaking furnace, approximately estimates the temperature of the ladle refractory from this measured value, and Based on the approximately estimated canceled refractory temperature, the amount of heat of molten steel transferred to the ladle refractory after tapping is predicted, and the steelmaking furnace exit tiA temperature is corrected.

The reason for not directly measuring the temperature on the ladle-resistant surface is that the condition of the ladle-resistant surface is not constant, and since radiation thermometers require water cooling, there is a risk of a steam explosion. This is because, as a result of numerous ladle heating tests, the present inventors have found that there is a correlation among the heating atmosphere temperature, combustion exhaust gas temperature, and refractory surface temperature under constant heating conditions.

When measuring heating atmosphere temperature or combustion exhaust gas temperature, a simple thermocouple guarantees sufficient accuracy and has reliability that can be used for controlling fuel flow rate.

〔Example〕

The present invention will be described below based on illustrated embodiments.

As shown in FIG. 1, just before tapping from the converter, the ladle 1 is moved to the burner 2. A lid 4 with an exhaust pipe 3 is attached and heated by a burner 2. Thermocouples 5 and 6 are inserted into the inside of the refractory 1 and the exhaust pipe 3, and the heating atmosphere temperature TI of the ladle 1 and the combustion exhaust gas temperature T3 are measured, and the surface temperature T of the ladle refractory 7 is measured.
Estimate 2.

As shown in Fig. 2, each temperature always has a relationship of 'T', >T2>T, and there is a certain relationship between these if the heating pattern is the same, for example 'r , :Tz :'rff=,3o:2'7:
It is 24. Therefore, T2 can be estimated from T+ and Ta.

Since the temperature distribution of the refractory 7 is almost determined by the thermal characteristics and heating pattern of the refractory, by estimating the refractory surface temperature T2, the heat content of the refractory 7, that is, the amount of heat removed from the molten steel can be estimated. Based on this amount of heat removed, it is possible to predict the amount of drop in temperature of molten steel in the ladle, and the converter tapping temperature is corrected based on this. As shown in FIG. 3, if the refractory surface temperature T2 is high and the amount of heat removed is small, the converter tapping temperature is lowered.

Furthermore, in detail, the exhaust gas temperature T3 during the heating time in FIG. 2 is about 750°C, the refractory surface temperature T2 at this time is about 850'C, and the exhaust gas temperature T3 is displayed in the room moment by moment.

In the converter operation room, a tapping temperature correction graph for T3, for example, FIG. 3, is prepared, and based on this, the tapping temperature is appropriately corrected to make the tapping temperature as low as possible.

[Effect of the invention] As described above, the steelmaking furnace operating method of the present invention estimates the refractory temperature based on the heating atmosphere temperature of the ladle or the combustion exhaust gas temperature, and corrects the steelmaking furnace tapping temperature based on this. As a result, the temperature can be reflected in the steelmaking furnace tapping temperature controller to be as low as possible using a simple method.

Thereby, it is possible to reduce the steelmaking yield in the steelmaking furnace and the steelmaking costs such as the unit consumption of refractories and solvents.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a ladle used in the present invention, FIG. 2 is a graph showing the relationship between various temperatures during heating of the ladle, and FIG. 3 is a graph of the tapping temperature correction value. ■...Cancel, 2...Burner, 3...Exhaust pipe, 4...Lid,
5.6...Thermocouple, 7...Cancelled refractory, T,...Heating atmosphere temperature, T2...Refractory surface temperature, T,...Combustion exhaust gas temperature.

Claims (1)

[Claims] (1) Measure the heating atmosphere temperature or combustion exhaust gas temperature of the ladle that is heated immediately before tapping the steel in the steelmaking furnace, and approximately estimate the temperature of the ladle refractory using this measured value. A method for operating a steelmaking furnace, characterized in that the amount of heat transferred to the ladle refractory after tapping is predicted based on the temperature of the ladle refractory, and the steelmaking furnace tapping temperature is corrected.