JPS59140309A - Level measuring method of stored iron slag in blast furnace - Google Patents

Abstract

PURPOSE:To measure simply a stored iron slag level on an on-line basis by installing at least one couple of electrodes at a specified interval in furnace wall brick in the vicinity of the furnace bottom part of a blast furnace, and measuring continually the electric resistance of the brick by the electrodes. CONSTITUTION:A couple of electrodes 8a and 8b are provided in carbon brick 6 in the vicinity of the furnace bottom part 4 of a blast furnace by leaving a specified interval (b), and electrodes 9a and 9b are provided above the electrode 8a and below the electrode 8b respectively by leaving a specified interval (a). A specified electric current is passed between the electrodes 8a and 8b from a power source 10. The combined resistance R of the carbon brick 6 and molten iron 7 is obtained by an equation from the above-mentioned current value I and the voltage value V between the electrodes 8a and 8b. The K in the equation is (rho2-rho1)/(rho2+rho1). The stored iron slag level can be measured by the change in the resistance value which is measured continually.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the level of pig iron slag in a blast furnace, which allows the level of pig iron slag in a blast furnace to be easily measured online.

Figure 1 is a schematic vertical cross-sectional view of a blast furnace, and the raw material iron ore is
It is supplied together with coke into the furnace body 1 from the large bell 2 at the top of the furnace, and is reduced by hot air forced into the furnace body 1 through the tuyere 3 to become molten pig iron. The hot metal slag is accumulated in the furnace bottom 4 and discharged from the tap hole 5 provided in the furnace bottom 4 at regular intervals.

In blast furnace operation, understanding the level of hot metal slag accumulated in the furnace bottom 4 is important in determining the tapping cycle and performing stable and economical operation. That is, if the level of the stored pig iron slag becomes too high, the ventilation of the hot air forced into the furnace body 1 from the tuyere 3 deteriorates, and the furnace condition becomes unstable. In order to stabilize the unstable furnace condition, it is necessary to take measures such as increasing the amount of coke input or changing the amount of hot air, which leads to deterioration of operating costs.

However, in the past, there was no way to measure the level of slag stored, so the amount of slag stored at the bottom of the furnace was indirectly estimated by calculating the balance between the amount of raw material supplied to the furnace body and the amount of pig iron tapped. However, it was only a very rough guideline.

From the above-mentioned viewpoint, the present invention provides a method for measuring the level of pig iron slag in a blast furnace that can easily measure the level of pig iron slag in the bottom of a blast furnace online. At least one pair of electrodes are installed at predetermined intervals in the bricks that make up the furnace wall, and the electrical resistance of the bricks is continuously measured by the electrodes. The feature is that it measures the pig iron slag level.

Next, this invention will be explained in detail.

The area near the bottom of the blast furnace is made of carbon bricks that have good cooling efficiency for the furnace body. The carbon brick has a resistivity ρ1 of ρ, = 6.3×10 −3 Ωm and is electrically conductive. On the other hand, the resistivity of hot metal is ρ2
However, ρ2=1.3XIO-'Ωm, which is smaller than the resistivity of carbon bricks.

Therefore, by measuring the electrical resistance between two points of the carbon bricks that make up the furnace wall near the bottom of the furnace, it is possible to easily measure the combined resistance of the carbon bricks and hot metal without getting extremely low resistance. The change in the level of the stored pig iron slag can be determined from the change in the electrical resistance value obtained by continuously performing this measurement.

FIG. 2 is a diagram showing the basic principle of this invention, where 6 is a carbon brick (thickness: d), 7 is hot metal, and the carbon brick 6 is provided with a pair of electrodes 8a at a constant interval.

8b is attached, and further above the electrode 8a and the electrode W8b.
Several electrodes 9a and 9b are provided below at a constant interval a. By such a four-terminal method, the electrode 9
A constant current is caused to flow between a and 9b by a power source 1.0, and the current value (■) and electrode 8a.

From the voltage value V across 8b, the combined resistance R of the carbon brick 6 and the hot metal 7 can be determined by the following formula.

However, K-△knee production ρ2+ρ1 For example, a: o, 1m, b: 2m, d: 0.5
m, hot metal 7 is placed on the carbon brick 6 as shown in the figure.
exists, R=17mQ from the above equation, and when there is no hot metal in the part of the carbon brick 6, R=
It becomes 22.5 mΩ. In this way, the resistance value of the carbon brick 6 changes by about 25% depending on whether or not molten metal exists, so if this resistance value is continuously measured, it can be determined whether molten pig iron is present at the position of the carbon brick 6 or not. You can easily know what

FIG. 3 is an explanatory diagram showing an example of the method of the present invention, in which carbon bricks 6 constituting the bottom part 4 of the blast furnace are covered with paired electrodes 8a, 8.
b are attached horizontally at regular intervals, and an electrode 9a is provided to the left of the electrode 8a, and several electrodes 9b are provided to the right of the electrode 8b.

Reference numeral 12 denotes an AC four-terminal resistance measuring device, and the measuring device 12 includes an AC power supply (
120I(Z) 10, and an arithmetic unit 1], and the current value between the electrodes 9a and 9b and the electrodes 8a and 8b are
The electrical resistance of the carbon brick 6 is calculated by the arithmetic unit 11 from the voltage value V between them, and is output.

The reason why we adopted a resistance measurement system (double bridge method) based on the four-terminal measurement method in measuring the electrical resistance described above is that this measurement method can eliminate the influence of contact resistance between the carbon brick and the electrode. , and the reason for using alternating current is,
This is because it is possible to eliminate the influence of thermoelectromotive force caused by the temperature difference between each electrode.

As shown in FIG. 4, when the outside of the carbon brick 6 is covered with the iron skin 13 and the electrical insulation between the carbon brick 6 and the iron skin 13 is insufficient, the tip of the electrode 14 is inserted into the carbon brick 6. The outer periphery of the electrode] 4 is covered with insulating material 15.
The influence of the iron skin 13 can be reduced by covering it with.

FIG. 5 is a diagram showing the hot metal level obtained as a result of measurement by the method described above, and FIG. 6 is a diagram showing level fluctuations during actual operation. As shown in Figure 5, it was confirmed that the electrical resistance value of the carbon brick changed by approximately 17% in response to the hot metal level, and it was also measured that the level during actual operation varied as shown in Figure 6. .

FIGS. 7 to 9 show other embodiments of the arrangement of electrodes according to the method of the present invention. FIG. 7 shows electrodes 8a and 9a and electrodes 8a' and 9a' at opposite positions on the side wall of the bottom of the furnace. The electrodes 8a and 8 are provided vertically at regular intervals, respectively, and the electrodes 8a and 8 are provided on the bottom wall of the furnace bottom.
an electrode 8b connected to the electrode 9a and the electrode 9a';
and continuous electrodes 9b are provided at regular intervals, and
a, 9a and electrode 8b.

A resistance measuring device 12 is installed between the electrodes 9b and an electrode 8a'.

Similarly, a resistance measuring device 12' is provided between 9a' and electrodes 8b and 9b.

Further, FIG. 8 shows electrodes 8a, 8b and electrodes 9a, 9b arranged vertically at regular intervals on one side of the side wall of the furnace bottom, and electrodes 8a', 8a', 9a' and 9b arranged vertically at opposite positions on the other side of the side wall.
8b' and electrodes 9a', 9b' are provided, and a resistance measuring device 12 is provided between the electrodes 8a+9a and electrodes 8b, 9b, and electrodes 13a', 9a are provided.
Similarly, a resistance measuring device 12' is provided between the electrodes 8b' and 9b'.

FIG. 9 shows that electrodes 8a and 9a are provided horizontally at regular intervals on one side of the side wall of the furnace bottom, and electrodes 8b and 9b are provided horizontally at opposite positions on the other side of the side wall, and the electrode 8a
, 9a and electrode 8b, 91. ) resistance measuring device 1 between
2.

The electrode arrangement shown in FIGS. 7 and 8 is effective for measuring the uneven state of hot metal in the bottom of the furnace during and immediately after tapping. This electrode arrangement is effective in measuring the average level, which is not affected by the deviation of the hot metal in the bottom of the furnace.

As described above, according to the method of this invention, the level of stored pig iron slag in the blast furnace can be easily measured online, and the blast furnace operation can be performed stably and economically. effect is brought about.

[Brief explanation of drawings]

Fig. 1 is a schematic vertical cross-sectional view of a blast furnace, Fig. 2 is a diagram of the basic principle of this invention, Fig. 3 is an explanatory diagram showing an example of the method of this invention, and Fig. 4 is an explanation showing an example of the state of attachment of the electrode. Figure 5 is a diagram showing the hot metal level obtained as a result of measurement by the method of this invention, Figure 6 is a diagram showing level fluctuations during actual operation, and Figures 7 to 9 are electrode arrangements in the method of this invention. It is a figure showing an example. In the drawing, ■... Furnace body, 2... Large bell, 3... Tuyere,
4... Furnace bottom, 5... Tapping port,
6...Carbon brick, 7...Hot metal, 8b, 9a, 9b, 8a'+ sb', 9a',
9b'...electrode, 10...power supply, ]1.
・Arithmetic device, 12.12'...Resistance measuring device] 3.
- Iron skin, 14... Electrode, 15... Insulating material. Applicant Nippon Kokan Co., Ltd. Agent Natsuo Shioya (and 2 others) Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] Several at least one pair of electrodes are placed at predetermined intervals on the bricks constituting the furnace wall near the bottom of the blast furnace, and the electrical resistance of the bricks is continuously measured by the electrodes, and the change in electrical resistance value is measured. A method for measuring the level of pig iron slag in a blast furnace, characterized by measuring the level of pig iron slag in the bottom of the furnace.