JPS61217516A - Detection of slag level in converter - Google Patents

Abstract

PURPOSE:To surely detect the slag level in a converter by inserting a lance embedded with many temp. sensors at suitable intervals in the longitudinal direction into the converter and measuring continuously the temp. in the converter by the temp. sensors. CONSTITUTION:The many thermocouples 3a-3n are embedded at suitable intervals into the water cooling lance 2 to measure the temp. in the converter 1 during blowing in the stage of executing blowing by charging a molten metal 4 and slag 5 into the converter 1 and inserting the lance 2 therein. The top surface 5a of the slag 5 exists near the position where the temp. in the converter measured by the thermocouples 3a-3n exhibits the max. value and the slag height is easily detected from the position of the thermocouple. Slopping is thereby predicted and prevented or the improvement of a yield, the production of a low-N steel, etc., are made possible by controlling the rate of oxygen feed, the height of the lance 2, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting slag level in a converter.

[Conventional technology]

During converter operation, slag forms into an emulsion during blowing, but if the forming becomes excessive (-), slag overflows to the outside of the furnace, so-called slopping. This not only causes a decrease in the iron yield, but also makes it difficult to continue stable blowing.

This is a major obstacle in implementing efficient converter operations. For this reason, when slopping occurs, slopping is suppressed by adding a re-forming sedative that adjusts the oxygen delivery rate during blowing.

By the way, during normal stable blowing in a converter, the inside of the furnace is in a gas atmosphere, but before slopping occurs, slag due to foaming rises and the inside of the furnace becomes a slag atmosphere. Therefore, by measuring the atmosphere inside the furnace, it is possible to predict the occurrence of slopping, and by taking early countermeasures, it is possible to prevent the occurrence of slopping. Various slab level detection methods have been proposed for this purpose. , some of which are in practical use.

One of these methods is to measure the slag level during blowing using a tipron temperature waveform. For example, JP-A-59
Publication No. 166612 discloses that an in-furnace optical photometer is installed in a passage hole provided in the converter wall to detect the intensity and/or wavelength change of the light in the furnace during operation, and to record this detected value in advance. A method is disclosed for detecting an abnormal reaction by comparing it with an intensity and/or wavelength change abnormal reference value set for each type of in-core abnormal reaction.

[Problem that the invention seeks to solve]

The former method, that is, the method of measuring the slab level from the sublance temperature waveform, has problems in that continuous measurement is difficult and the probe is expensive. In addition, the latter method not only has low measurement accuracy and lacks reliability during blowing in a converter in an adverse environment of high temperatures and dust, but is also expensive, requires a large installation space, and has a short life. , there are many problems.

[Means for solving problems]

The inventors of the present invention discovered that when the furnace is in a gas atmosphere, the temperature inside the furnace is maintained at approximately 1,500°C (2), whereas when the furnace is in a slag atmosphere, the temperature inside the furnace rises to approximately 1,650°C. It was also noted that the temperature near the interface between the gas atmosphere and the slag atmosphere was even higher than this temperature.

A large number of temperature sensors are embedded at appropriate intervals along the length of the lance, and each temperature sensor continuously measures the temperature inside the furnace to detect the slag level.

[For production]

The temperature inside the furnace is continuously measured by each temperature sensor, and the slag level is detected from the position of the temperature sensor that shows the highest temperature.

〔Example〕

FIG. 1 is a schematic diagram of a converter for explaining the present invention, in which 1 is a converter, and 2 is a water-cooled lance inserted into the converter 1. As shown in FIG. 2, a large number of thermocouples 3a to 3n are embedded in the lance 2 at appropriate intervals in the length direction (in the embodiment, the interval 1 is 500 mm). The depth from the point to the measurement point of the thermocouples 3a to 3n was 7 mm in the example, but according to the experimental result I: 2 mm≦d≦
A range of 50 mm was found to be desirable. 4 is the molten metal 5 is a slab, hs is the height from the surface of the molten metal @ 4 to the top surface of the slag 5 before the start of blowing, and hL is the height from the surface of the molten metal 4 to the tip of the lance 2. Show height.

Next, the present invention will be explained in detail. First, the lance 2 is inserted into the converter 1 to detect blowing, and the thermoelectromotive force of each thermocouple 6a to 3n is continuously measured. .

At this time, 1, the number of thermocouples in the slag atmosphere is approximately 1650.
0C, and in an upper gas atmosphere (: some thermocouples have a temperature of about 1
500°C, near the interface between the slab atmosphere and the gas atmosphere: As shown in Figure 3, a certain thermocouple indicates a particularly high temperature. By determining the heights from 5a to 6n, the height of the slag 5 can be detected from the position of the thermocouple that showed the highest temperature.

FIG. 4 shows a comparison between the slag height B measured by the temperature waveform of the sublance and the slag height B measured by the present invention, and shows that there is an extremely good correlation between the two.

According to the present invention (2), the upper surface 5a of the slug 5 has thermocouples 6a to
Since it can be seen that the furnace temperature measured by 6n is near the position where the maximum value is shown, the slag height can be easily detected from the position of the thermocouple. In addition, it is clear from experiment ζ2 that slopping occurs when the top surface of the slag exceeds a certain height, so when the thermocouple at a position corresponding to this height 2 shows the maximum temperature, an alarm is issued. By doing so, it is possible to predict the occurrence of slopping in advance.

When an alarm is issued, the occurrence of slopping can be prevented by lowering the lance 2 to perform a hard blow, or by introducing a foaming calming material into the furnace. Although the warning was issued,
It became clear that the above slopping could be prevented.

In the above description, a case has been described in which a thermocouple is embedded in the lance, but a temperature sensor other than a thermocouple may be used.

〔Effect of the invention〕

As is clear from the above explanation, 1. The present invention embeds a large number of temperature sensors in the lance to continuously measure the temperature inside the furnace, and detects the slag height from the results. can be predicted in advance. For this reason, it is necessary to control the amount of oxygen fed and the height of the flow to prevent slopping and to produce low (N) steel. can be mentioned.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a converter for explaining the present invention. Fig. 2 is a schematic diagram of a lance used in the present invention. Fig. 3 is a diagram showing the relationship between the position of a thermocouple and temperature. Fig. 4 Converter, 2: Lance, 3a to 6n:
thermocouple. 4: Molten metal%5 varnish slag. Agent: Patent Attorney San Roki Kimura 4TSl

Claims (1)

[Claims] A lance with a large number of temperature sensors embedded at appropriate intervals in the length direction is inserted into the converter, and the temperature inside the furnace is continuously measured by each temperature sensor, and the slag level is determined from the position of the temperature sensor that shows the highest value. A method for detecting slag level in a converter, characterized by detecting.