JPH10183211A - Operation of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blast furnace operating method which measures a raceway shape by measuring the thrust at the time of inserting a sonde and controls the various items of blasting based on the result. SOLUTION: The sonde having a circular conical pressure receiving head at the end part and fitting a load cell enabling measurement of the thrust at the time of inserting in the furnace, is inserted into the furnace from a bosh part of the blast furnace at the upper part of a tuyere. The height of the raceway is measured by measuring the thrust at the time of inserting, and the various items (blasting temp., oxygen enriching ratio, pulverized fine coal injecting quantity, etc.) are controlled so that the ratio of the height of the raceway to the preobtd. depth of the raceway becomes <=1.5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating a blast furnace, and more particularly to a method for operating a blast furnace based on a measurement result of a raceway shape by thrust measurement when inserting a sonde.

[0002]

2. Description of the Related Art The shape of a raceway formed in front of a tuyere of a blast furnace, particularly the height of the raceway, is an important factor that reflects the conditions inside the furnace.

[0003] For example, the accumulation of powder (coke powder or the like) near the raceway increases the blowing pressure of hot air blown from the tuyere, and the raceway is developed upward. In addition, during the operation of blowing a large amount of pulverized coal, the accumulation amount of powder in the raceway increases, and the raceway is developed upward. As described above, when the raceway is developed upward, the heat load on the furnace wall increases, which is a negative factor for extending the life of the blast furnace.

As a method of detecting a raceway boundary, a method of measuring a static pressure in a furnace by inserting a sonde into a furnace, a method of measuring a thrust at the time of inserting a sonde into a furnace, and a race The method of detecting the way boundary, the method using an optical fiber image to detect the raceway boundary based on the observed motion of the furnace interior by inserting a sonde equipped with an optical fiber into the furnace, CO in the raceway,
Using the absence of H ₂ Wahoton, a method for detecting the raceway boundary by measuring the gas composition,
Etc. are known. Attempts have also been made to measure the boundary of the raceway by observing the porosity of the filling layer from the transmittance of the laser beam.

However, these methods cannot be said to be accurate measurement methods except for the method using an optical fiber image, and cannot directly measure the raceway shape (particularly the raceway height). No, just guess. On the other hand, the method using an optical fiber is also accurate, but cannot be said to be an advantageous measurement method in terms of cost and maintenance. Moreover, there is no report on a method of reflecting the raceway shape measured (estimated) as described above in blast furnace operation.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and a blast furnace which measures the shape of a raceway, particularly the height of the raceway, and controls the blower specifications based on the result. The purpose is to provide operating methods.

[0007]

In order to solve the above-mentioned problems, the present inventor has proposed a method of measuring the insertion thrust of a sonde, which is the cheapest and simplest method among conventionally proposed methods. A method for directly measuring the way shape (especially, raceway height) was studied. As a result, a sonde having a conical pressure receiving head at the tip is inserted into the furnace from the upper Bosch section of the blast furnace tuyere, and the thrust at that time is measured with a load cell to measure the raceway shape (raceway height). Confirmed that it is possible.

Further, it was found that the raceway depth was estimated by the Hanedano equation described later, and that the operation of the blast furnace could be stabilized by setting the ratio of the raceway height to the raceway depth to be equal to or less than a predetermined value. The present invention has been made.

The gist of the present invention resides in the following blast furnace operating method.

A sonde having a conical pressure receiving head at the tip and equipped with a load cell capable of measuring a thrust during insertion into the furnace is provided with a tilt angle at which the vicinity of the upper end of the raceway can be measured from the blast furnace Bosch portion above the tuyere. The raceway height is measured by inserting it into the furnace and measuring the thrust at the time of insertion, and the ventilation specifications are adjusted so that the ratio of the raceway height to the raceway depth obtained in advance is 1.5 or less. A blast furnace operating method characterized by controlling.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The blast furnace operating method of the present invention will be specifically described below.

First, it will be described that it is possible to recognize the raceway boundary and measure the height of the raceway by measuring the sonde thrust.

Acrylic on both sides, 20 mm in the furnace direction
Using a flat plate two-dimensional model (width 100 mm, length 500 mm, height 900 mm) of a blast furnace lower coke bed provided with a protruding tuyere having an inner diameter of 8 mm, polypropylene spheres were filled inside, and 0.0244 Nm ³ from the tuyere. / S
Was blown to form a raceway. Then
A sonde equipped with a load cell was vertically inserted at a constant speed from the packed bed above the raceway, and the thrust at that time was measured by the load cell.

FIG. 1 schematically shows a change in thrust with time.
As can be seen from this figure, the top of the raceway boundary,
And the lower end was clearly identified.

Therefore, the sonde is formed in the blast furnace Bosch section above the tuyere so as to form an inclination angle at which the vicinity of the upper end of the raceway can be measured, that is, the tip of the inserted sonde forms a raceway boundary near the upper end of the raceway. It was installed so that it could penetrate and enter the raceway at an angle, and was inserted into the furnace. Note that the inclination angle and the installation position of the sonde may be the inclination angle and the installation position at which the vicinity of the height can be measured, using the height of the raceway predicted from the conventional operation experience as a guide.

This sonde is equipped with a load cell for measuring thrust, and a cone-shaped pressure receiving head is attached to the tip of the load cell.

The reason why the thrust at the time of inserting the sonde into the furnace is measured by the load cell is that it is inexpensive and easy to maintain.

The reason why the pressure receiving head of the sonde is made conical is as follows.

Using a sonde to which several types of pressure receiving heads each having a shape as shown in FIG. 2 were attached, the thrust at the time of insertion was measured by the above-described two-dimensional flat plate model, and the optimum pressure receiving head shape was examined.

FIG. 3 schematically shows the measurement results of the thrust hunting index (thrust peak number + relative thrust drop width) performed by using a sonde to which each pressure receiving head is attached. The smaller the thrust hunting index, the better.

From these results, a pressure receiving head (a pressure receiving head of TYPE 2 in FIG. 2) having a conical tip and a tip angle of a vertical section including a central axis (hereinafter, simply referred to as a tip angle) of 30 degrees is optimal. It was confirmed that there was. Note that the tip angle is not limited to 30 degrees, and if it is 25 to 35 degrees, almost the same good results as in the case of 30 degrees can be obtained.

FIG. 4 is a diagram schematically showing the maximum value of the probe thrust with respect to the probe insertion speed measured by the hot blast furnace model device. Sonde insertion speed is 1.2m / min
Is exceeded, the maximum value of the sonde thrust increases sharply and the load on the sonde increases. On the other hand, when the insertion speed is low, the measurement takes time. Therefore, the insertion speed of the sonde into the furnace is 1.2 m / m with a small load on the sonde.
It is desirable that the speed be as high as possible.

In the blast furnace operating method of the present invention, the boundary of the raceway is recognized by measuring the thrust at the time of insertion into the furnace using the sonde inserted from the blast furnace bosh above the tuyere as described above. While measuring the height of the way and estimating the raceway depth, the ratio (HR) of the raceway height (H _R ) to the raceway depth (D _R )
_(R / D _R ) is controlled to 1.5 or less.

The ratio (H _R / D _R ) of the raceway height to the raceway depth is set to 1.5 or less for the following reason.

According to the knowledge obtained by using the hot blast furnace model apparatus, as schematically shown in FIG. 5, when the powder ratio inside the raceway increases, the ratio of the raceway height to the raceway depth ( H _R / D _R ) increases. This is undesirable because it increases the heat load on the furnace wall.

As shown in FIG. 6, when H _R / D _R exceeds 1.5, a furnace wall flow is observed, the furnace wall temperature rises sharply, and the furnace body heat load increases.

Therefore, the ratio (H _R / D _R ) of the raceway height to the raceway depth is set to 1.5 or less.

The raceway depth D _R is the Hatano formula, RF can be inferred with respect to (dimensionless blast energy) ( "Iron and Steel", 62 (1976) P25). Here, the definition of RF and the Hanedano equation are as follows.

[0029]

(Equation 1)

Where ρ _g0 : gas density in standard condition ρ _p : density of coke before tuyere V _g : amount of Bosch gas S: cross-sectional area of tuyere T _t : gas temperature before tuyere T ₀ : temperature in standard condition ( 273K) P: blowing pressure P _0: acceleration of gravity: atmospheric d _pt: feather preoral coke particle diameter D _R: Raceway depth D _T: feather caliber g.

The ratio of the raceway height to the raceway depth (H _R / D _R ) is controlled by adjusting the blower specifications, that is, the blower amount, the blower temperature, the oxygen enrichment rate, the pulverized coal injection amount, and the like. Just do it. For example, when the ratio (H _R / D _R ) between the raceway height and the raceway depth exceeds 1.5, the amount of air blown and / or the amount of pulverized coal injected is reduced so that the ratio becomes 1.5 or less. .

According to the blast furnace operating method of the present invention, the shape of the raceway, particularly the height of the raceway, can be measured more easily and inexpensively than the method using an optical fiber image and the like. By adjusting the blowing specifications, it is possible to prevent the accumulation of powder near the raceway and to perform a stable operation, suppress a rise in the heat load on the furnace wall, and extend the life of the blast furnace.

[0033]

[Example] For a blast furnace with a furnace volume of 4800 m ³ ,
The operation was performed by the blast furnace operation method of the present invention.

The sonde used had an outer diameter of 8 as shown in FIG.
9.1 mm outer cylinder 3 and 17.3 mm outer diameter inner cylinder 4
The outer cylinder 3 is an air-cooled double pipe equipped with a load cell 5 for thrust measurement (maximum allowable load 2t). In addition, the tip of the sonde
2, the cone angle is 30 degrees and the bottom is 45m
The pressure receiving head 6 of mφ was mounted.

As shown in FIG. 7, this sonde is passed through a blast furnace Bosch section (A section in FIG. 7) vertically above the tuyere 1 by 3 m at each of the four tuyere sections adjacent to each other to form a horizontal plane. It was installed so that it could be inserted in the direction of 60 degrees downward.

Table 1 shows the blower specifications during operation.

[0037]

[Table 1]

During operation under such conditions, the above-mentioned 4
The thrust during insertion was measured periodically and alternately using this sonde, and the raceway height was measured for each tuyere with the sonde attached.

Further, the RF is calculated based on the airflow specifications for each tuyere, the raceway depth is estimated by the Hanedano formula, and the ratio (H _R / D _R ) of the raceway height to the raceway depth is calculated. Regarding the tuyeres with the same ratio exceeding 1.5, the blowing parameters were controlled so that H _R / D _R became 1.5 or less while keeping the total blowing volume of all tuyeres constant.

At this time, the furnace wall temperature and the blowing pressure in the vicinity of the Bosch portion were measured and compared with the furnace wall temperature and the blowing pressure in the case where the conventional operation method without controlling the blowing parameters as described above was performed. .

Table 2 shows the results. As is clear from the results, by performing the blast furnace operating method of the present invention, the furnace wall temperature was 200 ° C. at the maximum, and the blast pressure was 0.3 mm at the maximum.
A decrease of about kg / cm ² was observed.

[0042]

[Table 2]

[0043]

According to the blast furnace operating method of the present invention, the shape of the blast furnace raceway can be measured simply and inexpensively.
This can be reflected in the operation of the blast furnace to perform a stable operation, suppress the rise in the heat load on the furnace wall, and extend the life of the blast furnace.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a temporal change in thrust when a sonde is inserted.

FIG. 2 is a view showing various shapes of a pressure receiving head.

FIG. 3 is a diagram showing hunting indices when sondes equipped with pressure receiving heads of various shapes are used.

FIG. 4 is a diagram showing the maximum value of thrust with respect to the insertion speed of the sound.

FIG. 5 is a diagram schematically illustrating a relationship between a powder ratio inside a raceway and a ratio of a raceway height to a raceway depth.

FIG. 6 is a diagram schematically showing a relationship between a ratio of a raceway height to a raceway depth and a furnace wall temperature.

FIG. 7 is a schematic explanatory view of a method for installing a sonde.

FIG. 8 is a diagram showing a schematic structure of a sonde.

[Explanation of symbols]

 1: Tuyere 2: Raceway 3: Outer cylinder 4: Inner cylinder 5: Load cell 6: Pressure receiving head 7: Furnace wall 8: Seal

Claims (1)

[Claims] 1. A sonde having a conical pressure receiving head at the tip and equipped with a load cell capable of measuring thrust during insertion into a furnace is provided with a slope capable of measuring the vicinity of the upper end of a raceway from a blast furnace bosch portion above a tuyere. The raceway height is measured by measuring the thrust at the time of insertion into the furnace at a corner and measuring the thrust at the time of insertion. A blast furnace operating method characterized by controlling the source.