JPS60141813A - Method for controlling refractory wall of refining furnace for molten steel - Google Patents

Abstract

PURPOSE:To detect exactly the residual thickness of the refractory wall of a converter as well as the transition thereof with time and to discover the abnormal wear of the refractory wall in an early stage by detecting the fluctuation in the temp. during one cycle of the operation including the time while the furnace is empty by the thermocouples embedded in the refractory walls in the stage of operating the converter. CONSTITUTION:Thermocouples A are embedded into the refractory wall of a converter at 100-150mm. space from the inside wall and the temp. during refining when the cycle consisting of raw material charging, refining and tapping is repeated increases as shown in the curve I in the stage of operating the converter. When the inside of the furnace after tapping is empty, the temp. falls like the curve II and the temp. difference DELTAT is detected during this time. The temp. is compared with the value DELTAT calculated preliminarily from the relation between the heat conductivity of the refractory wall and the distance from the inside surface of the refractory wall to the position A and the distance DELTAL from A to the inside surface of the refractory wall is exactly estimated. The danger for the erosion of the furnace wall owing to the abnormal wear of the refractory wall is predicted therefrom and a countermeasure is effected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a furnace body management method for a molten steel refining furnace (hereinafter referred to as a converter) such as a converter.

[Background technology]

Accurately detecting the remaining thickness of the refractory wall during operation in converters, etc., detecting abnormalities early, and taking appropriate measures to protect the furnace body will ensure stable and efficient operation and maintain the specified production volume.
This is extremely important for reducing costs and extending the life of the furnace.

In particular, in recent years, in response to the increase in production scale, the internal volume of converters, etc. has continued to expand, and production speed has also increased dramatically, and the thermal and physical loads placed on fireproof walls have become increasingly severe. The need to strictly control the thickness of fireproof walls has become even more important.

Therefore, various methods for detecting the thickness of fireproof walls have been proposed. For example, as shown in Japanese Unexamined Patent Publication No. 52-58003, thermocouples are buried in advance in the thickness direction of a fireproof wall to form a circuit that includes all the thermocouples, and due to corrosion of the fireproof wall, A method of detecting the entire remaining thickness of a fireproof wall by thoroughly detecting the disconnection of the detection circuit, and a method of detecting the entire remaining thickness of the fireproof wall,
As shown in Publication No. 4, the temperature at different points in the wall thickness direction is measured by a trigger signal on a signal indicating a phenomenon inside the blast furnace, which is detected by a m degree detection sensor embedded in the refractory wall of the blast furnace. By analyzing the relationship between the time delay of the correlation between one signal and each temperature measurement signal and the radial distance of each temperature measurement point from the core, the location of damage to the refractory wall can be determined. methods have been provided.

However, with the above-mentioned method, although the former method is simple, it detects the entire thickness of the fireproof wall by breaking the thermocouple, so it can only detect the wear transition state intermittently. It had many problems, such as having a negative impact on the environment.

In addition, in the latter case, the entire wear and tear trend can be detected relatively accurately and continuously, but signal processing is required, making the equipment complex and expensive. It had many problems, such as having a negative impact on people.

OBJECT OF THE INVENTION The present invention provides a complete and highly reliable method for controlling the thickness of a fireproof wall, which fundamentally solves the problems of the conventional methods.
The purpose of this is to accurately and easily understand the remaining thickness of the converter refractory wall and its chronological changes, so that abnormal wear and tear of the refractory wall can be detected early, and prompt and appropriate measures can be taken to complete the reactor. All maintenance and management is to be carried out.

[Structure 9 of the Invention] The gist of the fireproof wall management method for a molten steel refining furnace according to the present invention is that thermocouples embedded in the fireproof wall of a converter, etc. The remaining thickness of the fireproof wall is estimated by detecting the entire temperature fluctuation range within the temperature range and using the relationship between the temperature fluctuation range determined in advance by heat transfer calculation and the distance from the inner surface of the fireproof wall to the buried position of the thermocouple. be.

The details are described below. In the cycle of raw material charging, refining, and tapping during the operation of a converter, etc., the present inventors
We investigated the relationship between the maximum temperature of a certain thermocouple embedded in the bricks of the furnace wall, the range of temperature fluctuation within one cycle, and the distance from the inner surface of the refractory wall to the thermocouple, but it was found that various operational factors are involved. .

No clear correlation was found between the two. Therefore, we performed a detailed analysis using -dimensional unsteady heat transfer calculation, and determined the molten steel temperature,
When we investigated the effects of charging time, empty furnace time, etc., we found that empty furnace time had the greatest effect on the relationship between the temperature fluctuation width and the distance from the inner surface of the refractory wall in terms of thermocouple weight. Therefore, in order to estimate the amount of corrosion damage from the temperature inside the brick, it was found that it is best to use the air furnace time sound parameter ξ parameter based on the relationship between the temperature fluctuation width and the distance from the inner surface of the refractory wall to the pP-couple. .

[Embodiments of the invention]

Hereinafter, the embodiment will be described in detail based on the drawings showing all the embodiments. FIG. 1 is a diagram showing the entire principle of the present invention, and curve 1, If, shows the maximum and minimum temperature distributions within the fireproof wall. In-furnace IC? While holding the 8 iron, the refractory wall gradually heats up and reaches its maximum temperature as shown by curve I. When the inside of the furnace is empty, the refractory wall is allowed to cool and reaches the lowest temperature as shown by curve (2). Temperature fluctuation range ΔTt - Detectable thermocouple position A
varies depending on the brick thermal conductivity and the oven time, but for bricks with a thermal conductivity of 8 to 15 KCat/mhr°C and an oven time of 5 minutes, it is within 200 degrees from the inner surface of the fireproof wall. Therefore, it is sufficient to embed thermocouples at intervals of 200 fm, but in reality, the range of temperature fluctuation is minute within 100 fm from the inner surface of the fireproof wall, so thermocouples should be buried at 1.0 fm intervals. OO~
It is desirable to bury them at intervals of 150 mounds.

The entire temperature fluctuation range was detected using the buried thermocouples under the above conditions, and each space was determined based on the relationship between the temperature fluctuation range determined in advance by unsteady heat transfer calculations and the distance between the inner surface of the fireproof wall and the thermocouple buried position. The total amount of melting loss is calculated for each furnace hour, but the method for doing this can be done by reading the temperature fluctuation range sound from the temperature measurement chart, or by using a graph showing the relationship between the temperature fluctuation range and the amount of melting loss, as shown in Figure 2. The processing may be performed by a computer with
Any method of analysis may be used.

(9) Although the present invention is based on the assumption that the entire furnace is in a repeated charging and empty furnace state, the cycle only needs to include a charging furnace and an empty furnace during the cycle, and the method of dividing the cycle does not matter. That is, it is sufficient to detect the temperature fluctuation range from an arbitrary point in time until one cycle has passed.

In actual operation, it is conceivable that the empty furnace time will become extremely long due to the shutdown of the furnace body, etc., and the brick heat storage level will decrease, but even in that case, unsteady heat transfer calculations can be performed using the empty furnace time in actual operation. - or by omitting the previous period during which the brick heat storage level recovers.

FIG. 3 shows the total amount of erosion loss in the actual operation of the converter, estimated by the method according to the present invention. In fig.

The black circle-solid line is the total estimated amount of brick erosion for each cycle, and uneven ranking occurs due to the influence of slab coating, etc. By performing the entire process of taking the average while moving k1mth order, a smoothed curve as shown by the white circle-dashed line is obtained.

Therefore, in practice, when estimating melt loss, all smoothing should be performed using five or more values. As for the smoothing method, various methods have been proposed in the past, such as the moving average method, and the method is not limited.

Mayu, AGA IMS 1600 by black circle - dashed line
The measurement results using MBASURING 8YSTEM (commonly known as Profile Meter) are shown. The amount of brick erosion estimated by the method of the present invention is in almost good agreement with the measurement results using a profile meter.1 According to the method of the present invention, the amount of brick erosion estimated by the method of the present invention is extremely simple, continuous, and relatively accurate. It turns out that it is possible.

5. The method of the present invention can be used to manage not only converters but also refractory walls in fixed steel refining furnaces such as R1 (and DH) using the same method.

〔Effect of the invention〕

As described above, according to the fireproof wall management method of the present invention, it is possible to accurately and easily grasp the remaining thickness of the fireproof wall of a converter, etc., and its time-series trends, so that appropriate maintenance and management of the furnace body can be carried out. The effect of being able to do this is obtained.

[Brief explanation of drawings]

Figure 1 is a diagram showing the temperature distribution inside the brick, Figure 2 is a graph showing the relationship between the temperature i fluctuation range ΔT, which is an air furnace time sound parameter, and the distance ΔL from the inner surface of the refractory wall to the thermocouple. The figure is a graph showing the results of estimating the amount of brick erosion in a converter. Agent: Patent attorney Masaaki Akizawa and 2 others 57

Claims (1)

[Claims] (1) Thermocouples embedded in the refractory wall detect temperature fluctuations from any point in the operation of the molten steel refining furnace to the end of one cycle, and the temperature fluctuation range and fire resistance are determined by heat transfer calculations in advance. A fireproof wall management method for a steel refining furnace characterized by estimating the remaining thickness of the fireproof wall using sound related to the distance from the wall inner surface to the thermocouple embedding position.