JPS62257004A - Blast furnace hearth wall erosion detection method - Google Patents

Abstract

PURPOSE:To accurately detect the eroded state of the furnace floor wall of a shaft furnace in the circumferential and height directions thereof, by operating the erosion line of the furnace floor wall of each place on the basis of the measured temp. of each place and the temp. of the cooling water of the furnace floor wall. CONSTITUTION:In detecting the eroded state of a furnace floor wall, a heat transmission coefficient operation part 15 operates heat transmission coefficient (h) from the measuring point of two-point thermometers 11,12 which are arranged in the carbon briquet 8 of a part of the detection places of a plurality of erosion lines 9 in the circumferential or height direction of a shaft furnace, to cooling water on the basis of the measured values T1, T2 of two-point thermometers 11, 12. An erosion line operation part 16 uses said heat transmission coefficient (h) to operate the erosion line position X at the erosion line detection place where the other one-point thermometer 13 is provided. By this method, an eroded state (erosion profile) can be detected with high accuracy.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an improvement in a method for detecting the erosion condition of a blast furnace hearth wall in the circumferential direction or height direction, and in particular, a method that can accurately detect it at low cost. It provides:

[Conventional technology]

Conventionally, the status of erosion in the circumferential direction or height direction of the blast furnace hearth wall has been understood by detecting the positions of hearth wall erosion lines at multiple locations in the circumferential direction or height direction of the blast furnace hearth wall. ing.

The detection of the erosion line position has conventionally been carried out in Japanese Patent Application Laid-Open No. 51-2
As shown in Japanese Patent No. 9951, this is done by measuring the temperature of the hearth wall refractory bricks at two points at different depths from the steel shell and performing a steady one-dimensional heat transfer analysis.

This will be explained in detail with reference to the drawings.

Fig. 1 is a vertical cross-sectional view of the blast furnace hearth wall 1, where 2 is the atmosphere, 3 is the iron skin, 4 is the castable layer, 5 is the stave, 6 is the staple pipe through which cooling water passes, 7 is the stamp layer, and 8 is carbon. 9 shows the erosion line, 10 shows the hot metal, and 11.12 shows the thermometer. The thermometer 11 is buried at a depth a from the shell toward the center of the blast furnace, and the thermometer 12 is buried at a depth b so that the temperature of the carbon brick 8 can be measured. A hot hole is drilled between the iron skin 3 and the iron-bond brick 8 in order to install a thermometer, but it is not shown in FIG.

Now the measured temperature of thermometers 11 and 12 is TI, T2, thermometer 1
1 to 12, the distance between the measurement point of the thermometer 11 and the erosion line 9 is X, and the temperature of the erosion line 9 (1150°C)
If Tp is the thermal conductivity of the carbon brick 8, and λ is the thermal conductivity of the carbon brick 8, then the amount of heat transmission at the measurement point of the thermometer is Q, and the position of the erosion line 9 is X.
can be calculated and detected from equation (2) determined from equation (11).

X=L・(Tp T + )/(T 2-T
I)...(2) The method of detecting the erosion line position from two thermometers installed inside the carbon brick 8 in this way is called the two-point method, and the thermometer installed in this way is called a two-point thermometer. call.

Conventionally, as a method for detecting the erosion line, in addition to the two-point method, one point is detected at a depth a from the shell toward the center of the blast furnace on the stave-cooled or water-cooled hearth wall shown in FIG. 2 or 3. A thermometer 13 is provided so as to be able to measure the temperature of the carbon brick 8 at point (a), and the measured temperature T3 of this thermometer and the stave temperature measured by the water temperature needle provided for controlling the stave or iron skin temperature. There is a method based on the cooling water temperature TW.

This means that the distance between the 11 points (point a) of the thermometer 13 and the erosion line 9 is X, the thermal conductivity of the carbon brick is λ, and the thermometer 1
If the heat transfer coefficient from measurement point 3 (point a) to the cooling water is calculated and the temperature of erosion line 9 is Tp, then the heat flow rate Q is: λ Q" (Tp T3) = h (T3 TW)
-(3), and the position X of the erosion line 9 is: X=λ (T p T 3 ) / h (T : 1
-TV) -(41 is used for calculation detection.

Conventionally, the heat transfer coefficient is determined as follows and set as a constant. In the stave-cooled hearth wall of FIG. 2, the thermal conductivity of the carbon brick 8, the stamp layer 7, and the stave 5 between the measurement point a and the stave cooling water is λ, λ7. λ5 and distance lθ,j! T,j! It is determined based on a. The thermal conductivity λ and λ7°5 are determined by off-line physical property values.

In addition, in the sprinkler-cooled hearth wall of Fig. 3, the thermal conductivities of the carbon brick 8, the stamp layer 7, and the steel shell 3 between the measurement point a and the steel shell cooling water are λ, λ7. λ3 and heat transfer distance ls.

17.13. The above thermal conductivity λ,
λ7. λ3 is determined based on off-line physical property values.

As mentioned above, the position of the erosion line is detected from one thermometer (hereinafter referred to as one-point thermometer) installed inside the carbon brick by effectively utilizing the water temperature needle etc. installed for stave or iron skin temperature control. This method is hereinafter referred to as the one-point method.

This method of detecting erosion in the circumferential direction or height direction of the blast furnace hearth wall using this one-point method (hereinafter referred to as the "erosion profile detection method") is superior to the erosion profile detection method using the two-point method described above. This has the advantage that the number of holes and thermometers required to be buried is greatly reduced, and equipment construction costs and profile detection equipment costs are significantly reduced.

[Problem that the invention seeks to solve]

However, the erosion profile detection method using the one-point method described above has lower accuracy in detecting the erosion line position than the two-point method for detecting the erosion line position for reasons explained later, especially in situations where carbon brick erosion has progressed, such as at the end of the furnace age. cannot take appropriate measures to protect the bottom of the hearth.

The reason why the one-point method has lower erosion line position detection accuracy than the two-point method is as follows.

That is, in the one-point method, the heat transfer resistance from the temperature measurement point to the stave cooling, for example, the contact surface between the brick 8 and the stamp layer 7, the contact surface between the stamp layer 7 and the stave 5, and the contact surface between the stamp layer 7 and the iron skin 3. Heat transfer resistance of air layer generated in stave pipe 6
Since the amount of scale attached to the inner surface or the water cooling surface of the steel shell 3 cannot be determined, these uncertain factors are
4) It is not reflected in the heat transfer coefficient h (constant) in equation.

Furthermore, regarding the stamp layer 7, the thermal conductivity changes greatly due to the effects of bulk specific gravity at the time of construction (which cannot be known until the actual construction is performed) and deterioration due to thermal expansion and contraction over time. Although the scale thickness changes over time, in the conventional one-point method, the heat transfer coefficient in equation (a) is given as a fixed constant.

Incidentally, the thermal conductivity of carbon bricks is fixed, and there is almost no change in its thermal conductivity over time.

[Means for solving problems]

In order to solve the problems in the erosion profile detection method using the one-point method, the present invention provides a plurality of erosion line detection points in the circumferential direction or height direction of the blast furnace hearth wall when periodically performing erosion profile detection. 2 installed in a part of
Using a point thermometer, calculate and determine the heat transfer coefficient from point a to the cooling water, including uncertainties and/or aging change factors, etc. The factor group effectively utilizes the characteristics that exhibit almost the same behavior in the circumferential direction or the height direction of the blast furnace, and uses the heat transfer coefficient determined by the above calculation to perform another one-point method (the measurement point is one point a). This method accurately calculates and detects the erosion line at the point where the erosion line is detected using a thermometer.

The gist of the invention is as follows.

Thermometers for measuring the temperature at specific points (point a) in the thickness direction of the bricks are installed in the hearth wall bricks at multiple locations in the circumferential direction or height direction of the blast furnace hearth wall, and the thermometers at each location are installed. In the method of detecting the erosion condition in the circumferential direction or height direction of the blast furnace hearth wall by calculating the hearth mold erosion line position at each location based on the measured temperature and the hearth mold cooling water temperature, Inside the hearth-type bricks at some of the plurality of locations in the circumferential direction or height direction of the blast furnace hearth wall, there is a temperature difference in the thickness direction of the bricks on the inside of the furnace, which is farther from the measurement point of the thermometer (point a). A thermometer is installed to measure the temperature at a specific point (point B), and the heat transfer coefficient from point A to the cooling water is calculated based on the measured temperatures at points A and B at that point and the cooling water temperature. A method for detecting erosion conditions of a blast furnace hearth wall, characterized in that the erosion line positions at other locations are calculated based on the measured temperature at point a and the cooling water temperature at each location using the heat transfer coefficient.

The present invention will be explained in detail below based on the embodiment shown in FIG.

Fig. 4 is a longitudinal cross-sectional view of the hearth wall l of a stave-cooled blast furnace, where 14 is a hearth wall erosion state detection device, and 15 is a cooling water from a measurement point (point a) of a two-point thermometer 11.12. The calculation section 16 calculates the heat transfer coefficient up to the erosion lie? In the calculation section, 17 is an erosion condition display section such as a CRT.

When detecting the hearth wall erosion condition, the heat transfer coefficient calculation unit 15 detects a plurality of erosion lines 9 in the circumferential direction or the height direction of the blast furnace.
The measured values T+ and T2 of the two-point thermometer 11.12 installed in the carbon brick 8 at some of the detection points are given to the equation (11) to calculate the heat transfer amount Q. By giving the measured value T1 of the temperature gauge 11 and the stave cooling water temperature Tw of the water thermometer (not shown) to equation (5), 2
Calculate the heat transfer coefficient from the measurement point of the point thermometer (point a) to the cooling water.

h = Q/ (T + Tw)
(5) The erosion line calculation unit 16 is
Using the above heat transfer coefficient, the erosion line X at the erosion line detection location where the other one-point thermometer 13 is provided is calculated. In detail, the above heat transfer coefficient, the measured value Tl of the one-point thermometer 13, the stave cooling water temperature T W % erosion line temperature'
rp, for example, the eutectic temperature of iron-carbon system is about 1150°C (
6) Calculate the erosion line X by inputting it into the equation.

X=λ (T p-T :+) / h (T 3-
(6) The erosion line at the two-point thermometer design point can be calculated based on equation (2) using the two-point method, or calculated using equation (6) using the one-point method as T3=TI. Calculate based on formula. The erosion condition display section displays the calculated erosion line position group as follows.
Display the pattern. The above-described detection of the erosion state is performed periodically, for example, every 24 hours.

As described above, the present invention periodically detects the erosion line positions at multiple locations in the circumferential direction or height direction of the blast furnace hearth wall using the one-point method, and periodically detects the erosion profile. Using the two-point thermometers 11 and 12 installed at some of the detection points of the plurality of erosion line positions, the heat transfer coefficient from the 11 measurement points (point a) for each temperature to the cooling water is determined.

Since the uncertainty and/or aging factors in the one-point method show similar behavior in the circumferential direction or height direction of the blast furnace hearth wall, this heat transfer coefficient is different from the detection point of the erosion line position using the other one-point method. It can be regarded as the heat transfer coefficient from the measurement point (point a) of the one-point thermometer 13 to the cooling water. The heat transfer coefficient determined by including such uncertain and/or aging factors is used to calculate and detect the erosion line position at the erosion line position detection point using the other one-point method, so it is highly accurate. The location of the erosion line can be detected.

Therefore, the erosion situation (erosion profile) can be detected with high accuracy.

Since the erosion situation can be detected with high precision in this way, it is possible to take appropriate and prompt measures to protect the hearth bottom, especially in situations where carbon brick erosion has progressed, such as at the end of the furnace life. Measures such as strengthening cooling or blinding the tuyere directly above τ can be taken appropriately.

〔Example〕

The circumferential direction of the stave-cooled hearth wall 1 of a blast furnace with a content of about 3000 m and a hearth diameter of about 12 rn shown in FIGS. 5 and 6,
Of the 27 erosion line detection locations, 2-point thermometers were installed at 4 locations, and 1-point temperature gauges were set at 81 at the other 23 locations.
13 was installed, and two-point thermometers 11.12 were installed to detect the erosion profile in the circumferential direction on a daily basis.For each of the four locations where two-point thermometers 11 and 12 were installed, The heat transfer coefficient hn is calculated based on equations (1) and (5), and the heat transfer coefficients h+, h2 are calculated for each of the four locations.
．． Calculate the average value of h3゜h4, use this average heat transfer coefficient, and use the above average heat transfer coefficient for the remaining 23 locations where one-point thermometers 13 are installed. Based on the equation, the erosion line position X at each location was calculated, and the erosion line positions were displayed in a pattern as shown in FIG.

4 equipped with a two-point thermometer 11.12 as shown in Figure 5.6 above.
For each location, the erosion line position was detected using the conventional two-point method, the conventional one-point method, and the method of the present invention.

Specifically, in the conventional one-point method, a value measured off-line was used as the thermal conductivity of the stamp layer, and a determined heat transfer coefficient was used without taking into consideration the air layer and scale thickness, which cannot be measured.

On the other hand, in the method of the present invention, first, the heat transfer coefficient to the cooling water at a point (point a) is determined from the sum of the thermometers 11 at each of the four locations, and the average value of the heat transfer coefficients at the four locations is determined. Using the heat transfer coefficient, the measurement value of the thermometer 11 at each location, the cooling water temperature, and the erosion line temperature, the erosion line position was detected based on equation (6).

Table 1 shows the average deviation and maximum deviation of the erosion line position detected by the conventional one-point method and the method of the present invention from the erosion line position detected by the conventional two-point method.

Table 1 From Table 1, it is clear that the method of the present invention can detect the erosion line position with higher accuracy than the conventional one-point method, and can detect the erosion profile in the circumferential direction with high accuracy.

Although the above description has been made regarding the method for detecting the state of erosion on the wall of a stave-cooled hearth, the method of the present invention can also be applied to the detection of the state of erosion on the wall of a water-cooled hearth.

〔Effect of the invention〕

As detailed above, according to the method of the present invention, it is possible to detect the erosion situation of the hearth wall in the circumferential direction or height direction with high accuracy at low equipment cost, and to take appropriate measures to protect the hearth bottom. This can lead to significant benefits in extending the life of the furnace, such as preventing local breakouts.

[Brief explanation of drawings]

Figures 1 to 3 are explanatory diagrams of the conventional method, and Figure 4 is an explanatory diagram of the method of the present invention. l! , 6.7 are explanatory diagrams of examples and effects of the method of the present invention. 1... Hearth wall, 2... Atmosphere, 3... Iron shell, 4
... castable layer, 5... stave, 6.
...Stapipe, 7.Stamp layer, 8.
...Carbon brick, 9...Erosion line, 10
...Hot metal, 11...Thermometer, 12...Thermometer,
13... Thermometer, 14... Erosion situation detection device,
15...Heat transfer coefficient calculation unit, 16...Erosion line position calculation unit, 17...Erosion status display unit. Applicant New Japan fi! ! Tetsu Co., Ltd. Representative Patent Attorney Minoru Aoyagi Figure 5

Claims (1)

[Scope of Claims] Thermometers are provided in the hearth wall bricks at multiple locations in the circumferential direction or height direction of the blast furnace hearth wall to measure the temperature at a specific point (point a) in the brick thickness direction. , calculate the hearth wall erosion line position at each point based on the temperature measured by the thermometer at each point and the cooling water temperature on the hearth wall, and calculate the erosion status of the blast furnace hearth wall in the circumferential direction or height direction. In the detection method, there is a temperature in the hearth wall bricks at some of the plurality of locations in the circumferential direction or the height direction of the blast furnace hearth wall, which is higher than the measurement point (point a) of the thermometer. Specific point in the thickness direction of the inner brick (point b)
A thermometer is installed to measure the temperature of point A and B, and the heat transfer coefficient from point A to the cooling water is calculated based on the measured temperatures at points A and B and the cooling water temperature, and the calculated heat transfer coefficient is used. hand,
A method for detecting erosion status of a blast furnace hearth wall, characterized in that the positions of erosion lines at other locations are calculated based on the measured temperature at point a and the cooling water temperature at each location.