JP5418384B2 - Converter blowing control method - Google Patents

Description

  The present invention relates to a blowing control method for suppressing spitting (sprayed molten iron particles) during blowing in a converter of a steel manufacturing process.

  In a top-blowing or top-bottom blowing converter in a steel manufacturing process, oxygen is blown into molten iron in the converter to blow the carbon component to a desired component amount. In particular, in a large converter, it is necessary to blow molten iron of about 300 t at a time, and a large flow rate of oxygen is supplied. Oxygen is supplied from the top lance and bottom tuyere, but mainly from the top lance. At this time, if the iron oxide in the slag increases, it reacts rapidly with the carbon in the molten iron and bumps, and the oxygen jet from the upper lance collides with the molten iron. Spatter from the opening. This is called spitting (spattering molten iron particles).

Furthermore, since the profile of the refractory in the converter has changed and it is difficult to predict the liquid level of the molten iron, for example, when the lance height and the molten iron liquid level are close, the collision force due to the injected oxygen gas increases. , Spitting increases.
Spitting usually reaches about 0.1 to 0.5% of the amount of molten iron, which is one of the causes of molten iron yield deterioration in converter blowing. Not only that, the scattered molten iron particles adhere to the surrounding facilities and floors, causing environmental deterioration in the converter operation and equipment failure, which is a major problem in the converter operation.

JP-A-63-100331 JP-A-9-118908 Japanese Patent Laid-Open No. 8-20813

Several methods have been proposed to reduce spitting.
For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 63-100311) proposes to measure the molten iron liquid level with a microwave and control the lance position so that the positional relationship between the lance and the molten iron liquid level is always optimal. Has been. However, since it takes several minutes (5 to 10 minutes) to measure the molten iron liquid level before blowing, it greatly deteriorates the productivity of converter blowing and is not a practical solution. .

  In Patent Document 2 (Japanese Patent Laid-Open No. 9-118908), spitting (also referred to as a spark in the same document) is directly monitored and spited from an opening portion of an exhaust gas duct disposed in the upper part of the converter. It has been proposed to determine the occurrence status and control the lance height and oxygen supply amount. However, the dust concentration in the duct is extremely high, and there are many disturbances in monitoring from the duct opening, and analysis that contributes to control is not possible, so this is also not a realistic solution.

Patent Document 3 (Japanese Patent Application Laid-Open No. Hei 8-20813) monitors the spitting scattered from the converter furnace port by a monitoring unit such as a CCD camera, and determines the time point when the amount of spitting is the maximum. There has been proposed a method of supplying a sedative for slopping (a phenomenon in which slag formed in a furnace foams and overflows outside the furnace). However, the specific position of the monitoring unit is not specified, and measurement at the converter furnace port illustrated is difficult to distinguish between noise caused by fumes generated and flame and spitting. This is also not a realistic solution.
Therefore, there is no effective means at present, and the converter operator grasps the amount of spitting by visual observation and controls the lance position empirically.

  Therefore, in view of these conventional techniques, the problem is to accurately estimate the amount of spitting generated in the converter blowing operation, and by controlling the lance height and oxygen flow rate based on the grasped amount of spitting, the amount of spitting is controlled. An object of the present invention is to provide a converter blowing control method with good yield (good productivity) that suppresses occurrence of dusting.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have monitored spitting from the outside of the converter, and among the spitting scattered and dropped from the converter furnace port, the image by the imaging device is used. The amount of spitting that is above a certain concentration and the total amount of spitting (the amount of spitting derived from the difference between the theoretical decrease and the actual decrease in molten iron before and after the converter blowing operation) The inventors have found that they have a high correlation, and have reached the present invention. Here, the density means a color tone in an image obtained by imaging spitting. For example, in the case of 8-bit monochrome, black is 0, white is 255, and the color tone is expressed as a numerical value from 0 to 255. For 8-bit R (red), G (green), and B (blue) colors, each color It means the value when each color tone is expressed by a numerical value of 0-255. In actual measurement, the color tone of spitting is approximately 220 ± 30.
The gist is as follows.

(1) In the blowing method of injecting oxygen from the upper lance to the molten iron in the converter, spitting spattering and falling outside the converter furnace from between the furnace port and the exhaust gas duct, Based on the imaging process for imaging with an imaging device installed outside the converter furnace so as to satisfy the formula, the analysis process for image analysis of imaging information in the imaging process, and the information analyzed in the analysis process A control method for blowing a converter, comprising a control step of controlling a lance position.
1/4 * (Ls / Lt) * π / 4 * (d + σ) ² ≦ X ²
≦ (Ls / Lt) * π / 4 * (d−σ) ²
X: Diameter corresponding to one pixel or length of one side of a square corresponding to one pixel in the visual field of the monitoring device (mm)
Ls: Average density of imaging of spitting (molten iron particles) Lt: Density threshold value of imaging of spitting (molten iron particles) d: Average value of diameter of spitting (molten iron particles) (mm)
σ: Standard deviation of spitting (molten iron particles) particle size (mm)

  (2) The converter blowing control method according to (1), wherein, in the control step, an oxygen injection amount from an upper lance is controlled based on information analyzed in the analysis step.

  (3) When imaging the falling spitting, the spitting falling at a position below the converter steel outlet hole is imaged. (1) or (2) Blowing control method for the furnace.

  (4) The converter according to any one of (1) to (3), wherein the imaging device is installed outside a range where spitting scattered from a converter furnace port falls. Blowing control method.

(5) In the blowing method in which oxygen is injected from the upper lance into the molten iron in the converter, it is installed outside the converter furnace, and is scattered and dropped from between the furnace port and the exhaust gas duct outside the converter furnace. An imaging device that captures the spitting that satisfies the following formula, an analysis device that analyzes image information captured by the imaging device, and a lance position that is controlled based on the image analysis information of the analysis device A control device for blowing a converter, comprising:
1/4 * (Ls / Lt) * π / 4 * (d + σ) ² ≦ X ²
≦ (Ls / Lt) * π / 4 * (d−σ) ²
X: Diameter corresponding to one pixel or length of one side of a square corresponding to one pixel (mm) in the visual field of the monitoring device
Ls: Average density of imaging of spitting (molten iron particles) Lt: Density threshold value of imaging of spitting (molten iron particles) d: Average value of diameter of spitting (molten iron particles) (mm)
σ: Standard deviation of spitting (molten iron particles) particle size (mm)

  (6) The converter blowing control apparatus according to (5), wherein the control device controls an oxygen injection amount from an upper lance based on information analyzed by the analysis device.

  (7) When imaging the falling spitting with the imaging device, imaging the spitting falling at a position below the converter steel hole (5) or (5) The converter for blowing converters according to 6).

  (8) The imaging apparatus according to any one of (5) to (7), wherein the imaging device is installed outside a range in which spitting scattered from a converter furnace port falls. Blowing control device.

  According to the present invention, the spitting amount in the converter blowing operation can be predicted easily and accurately, and the spitting amount can be suppressed by using this to control the lance height and the oxygen blowing amount. Thereby, the yield of a converter blowing operation can be improved significantly by a simple method, and the productivity of the operation can be remarkably improved.

It is a figure which shows the concept of the apparatus structure for implement | achieving the method in this invention. It is a figure which shows the relationship between the spitting amount which carried out the imaging analysis by this invention, and theoretical theoretical spitting amount. It is a figure which shows the effect (spitting generation amount) in the converter blowing control by this invention. It is a figure which shows the effect (converter blowing operation yield) in the converter blowing control by this invention.

First, the imaging method of the spitting situation in an imaging process is demonstrated.
In the vicinity of the converter mouth, there is a flame jetting during blowing, so the brightness of the background and the brightness of spitting are the same, making it difficult to distinguish.
Therefore, it is desirable to take an image of spitting falling as far as possible below the furnace port. For example, it is located below the bottom surface of the converter, below the outlet hole of the converter (which means the space below the height of the converter outlet hole when the converter being blown is viewed from the front). The space up to the converter work floor is desirable. In addition, if possible, it is more desirable to take an image below half the height of the converter (the length from the bottom of the converter to the furnace opening when the converter being blown is viewed from the front). This is because, at this position, it is possible to distinguish the spitting sufficiently from the luminance difference of the spitting from the converter main body and the peripheral equipment as a background.

The imaging by the imaging device is preferably performed by performing an enlarged imaging from outside the falling range of spitting by using a telephoto lens from a distance. This is because a direct hit of spitting can be avoided and equipment protection for imaging is provided.
When imaging spitting with a telephoto lens, it is desirable that the following relationship exist between the range captured by one pixel of the imaging apparatus and the spitting (molten iron particles). This is a limitation due to the accuracy of image information when performing image analysis.
1/4 * (Ls / Lt) * π / 4 * (d + σ) ² ≦ X ²
≦ (Ls / Lt) * π / 4 * (d−σ) ²
X: Diameter corresponding to one pixel in the visual field of the monitoring device or length of one side of a square corresponding to one pixel (mm)
Ls: Average density of imaging of spitting (molten iron particles) Lt: Density threshold value of imaging of spitting (molten iron particles) d: Average value of diameter of spitting (molten iron particles) (mm)
σ: Standard deviation of spitting (molten iron particles) particle size (mm)

  Here, the amount of spitting mainly depends on the carbon content of the molten iron, but the imaging density and the diameter thereof are almost constant regardless of the carbon component of the molten iron. For this reason, the particle size distribution of spitting in normal operation (average particle size and standard deviation of particle size distribution), imaging density (threshold) that can separate spitting one by one, and spitting having an imaging density that is above the threshold By measuring the imaging density (average imaging density) in advance and determining the above Ls, Lt, d, and σ, the length of one side of a square corresponding to one pixel in the field of view of the monitoring device can be obtained.

  The arrangement of the imaging device can be determined according to the obtained size of one pixel. Therefore, if a long-focus telephoto lens is used, an imaging device can be installed at a location sufficiently away from the converter, but if it is a short-focus lens, it will approach the converter. The risk of receiving a direct hit increases. What is necessary is just to select a telephoto lens, the number of pixels of an imaging device, etc. so that an imaging device may be arrange | positioned in an appropriate place with the installation arrangement | positioning conditions around a converter.

Next, image processing of imaging information obtained by imaging performed in the analysis process will be described.
For example, the number of spitting having an imaging density of a certain level or more may be counted from the obtained imaging information. For this purpose, the imaging interval may be set so that the same spitting is not included in two consecutive imagings in continuous imaging in the same field of view of the imaging device. For example, when the falling speed of spitting in the imaging field of view is 10 m / sec and the vertical length of the field of view is 3.5 m, all the spitting is performed twice by imaging at intervals of 0.3 seconds. Imaging can be performed without imaging. This is uniquely determined from the field of view of the imaging apparatus and the speed of spitting at the imaging position. Incidentally, the shutter speed at the time of imaging is determined comprehensively from the spitting speed, the spitting diameter, and the capability of the imaging apparatus.

  Now, it is only necessary to perform image processing for counting the number of spitting based on the imaging information thus obtained. For example, as described above, if all the spitting is imaged so as not to be doubled, a spitting having a certain imaging density or more is extracted by binarization processing, and the number thereof is counted. Specifically, the number of spitting can be counted by capturing one spitting grain with at most four pixels and counting the pixels that occupy the most area among them, for example, in the analysis step described later. .

According to the experiments by the inventors, it has also been confirmed that the particle diameter and imaging density of spitting falling at about half the height of the converter are almost constant regardless of the type and amount of molten iron. The spitting particle size at this time is about 10 mm, and the standard deviation is about 1 mm. Further, the density of this imaging is 190 to 255 (monochrome 8 bits).
In addition, it is confirmed that binarization processing can be performed if an appropriate threshold is set for the spitting to be counted, and thereby the spitting to be counted can be separated.

It goes without saying that such an image analysis method is not limited to the above example, and any image analysis method can be used.
Finally, the control process will be described. The control step is a step for controlling the position of the converter lance in order to reduce the amount of spitting based on the obtained analysis information of spitting. For example, by knowing in advance the relationship between the number of spitting information and scattering information obtained by the image analysis described above and the lance position, the desired amount of spitting can be determined according to the number of spitting information and scattering information. The lance position can be controlled to be

In order to suppress the occurrence of spitting, it is also effective to control the oxygen supply amount. That is, the oxygen injection amount (blowing amount) from the upper lance can be controlled so as to obtain a desired spitting amount. However, since the oxygen supply amount is necessary for the combustion removal of the carbon component in the molten iron, which is the original purpose of blowing, it is not desirable to greatly change the oxygen supply amount.
Of course, the lance position control and the oxygen injection amount (injection amount) control can be individually controlled, and both can be controlled in conjunction with each other. Needless to say, such a control mode is not limited to the above example, and any control mode can be used. Similarly, the lance position and the oxygen injection amount are also examples of the control target, and are not limited to these.

A CCD camera with 512 × 480 pixels (monochrome 8 bit) was used as the imaging device. Attach a telephoto lens to this, and from the converter operating floor 30 meters away from the converter (the working floor extending below the bottom of the converter), when the converter is viewed from the front, on the center line, above the converter operating floor A 2 m position was imaged.
The spitting diameter measured in advance was 10 mm, and its standard deviation was 1 mm. At the above position, the average imaging density of spitting to be measured was 220 ± 30. Therefore, the threshold value (Lt) was set to 190.
From the above formula, the size of the field of view was set to be 3.072 m wide and 2.88 m long so that the one-pixel space length is a square of 6 mm.
The sampling time (imaging interval) was set to 25 milliseconds, and the shutter speed was set to 1/2000 seconds.
Figure shows a comparison of the amount of spitting analyzed for each converter blowing operation (referred to as 1 heat) and the theoretically calculated amount of spitting based on the molten iron weight measured before and after 1 heat. It is shown in 2. It was confirmed that the correlation was very good, and that the total amount of spitting could be predicted from the captured amount of spitting.

  Next, an experiment was conducted to confirm the effect of lance height control by spitting amount during converter blowing. The height of the molten iron in the converter was measured in advance, the lance was set at a position where the spitting amount could be suppressed, and the change in the theoretical spitting amount when one whole heat was blown at that position was used as a reference value. . That is, this reference value is oxygen blowing by an appropriate lance position.

In the embodiment of the present invention, the total spitting amount was predicted from the relationship obtained from the relationship shown in FIG. 2, and the lance position was controlled accordingly. In addition, the Example and comparative example of this invention do not measure the molten iron liquid level height in a converter beforehand, determine the lance position from the previous heat performance, and start oxygen blowing.
The comparative example was performed by empirical sensory lance position control by an operator as before. The result is shown in FIG.
As can be seen from FIG. 3, since the lance position is not appropriate in both the example and the comparative example, the embodiment according to the present invention has a large amount of spitting as in the comparative example. However, it can be seen that by performing lance position control by the method of the present invention, the level immediately becomes the same as the reference value, and the optimum lance height is controlled. Even when compared with the comparative example, the effect was clearly confirmed.

The above embodiments are examples of embodiments of the present invention, and the present invention is not limited to these embodiments.
FIG. 4 shows the yield drop due to spitting ((molten iron lost as spitting) when the blowing control method according to the present invention was carried out (Example) and when blown by the conventional method (Comparative Example). (Amount estimated from the weight of molten iron before and after blowing)) / (Amount of molten iron charged)). In the comparative example, the average yield drop is 0.25%, while in the embodiment of the present invention, the average is 0.05%. That is, it can be seen that the amount of molten iron lost by spitting has been drastically reduced to 1/5.

  The present invention can be used for converter blowing operation in a steel manufacturing process.

Claims (8)

In the blowing method of injecting oxygen from the upper lance to the molten iron in the converter, spitting that falls off the converter furnace from between the furnace port and the exhaust gas duct satisfies the following formula: As described above, an imaging process for imaging with an imaging device installed outside the converter furnace, an analysis process for image analysis of imaging information in the imaging process, and a lance position based on information analyzed in the analysis process A method for controlling the blowing of a converter, comprising a control step of controlling the converter.
1/4 * (Ls / Lt) * π / 4 * (d + σ) ² ≦ X ²
≦ (Ls / Lt) * π / 4 * (d−σ) ²
X: Diameter corresponding to one pixel in the visual field of the monitoring device or length of one side of a square corresponding to one pixel (mm)
Ls: Average density of imaging of spitting (molten iron particles) Lt: Density threshold value of imaging of spitting (molten iron particles) d: Average value of diameter of spitting (molten iron particles) (mm)
σ: Standard deviation of spitting (molten iron particles) particle size (mm)   2. The method for controlling the blowing of a converter according to claim 1, wherein in the control step, an oxygen injection amount from the upper lance is controlled based on information obtained by image analysis in the analysis step.   3. Blowing control of a converter according to claim 1, wherein when the falling spitting is imaged, the spitting falling at a position below a converter steel outlet hole is imaged. 4. Method.   4. The converter blowing control method according to claim 1, wherein the imaging device is installed outside a range where spitting scattered from a converter furnace port falls. 5. . In the blowing method of injecting oxygen from the upper lance to the molten iron in the converter, it is installed outside the converter furnace and is scattered and dropped from between the furnace port of the converter and the exhaust gas duct. An imaging device for imaging spitting so as to satisfy the following equation, an analysis device for image analysis of imaging information captured by the imaging device, and a control device for controlling the lance position based on information analyzed by the analysis device A blower control device for a converter, comprising:
1/4 * (Ls / Lt) * π / 4 * (d + σ) ² ≦ X ²
≦ (Ls / Lt) * π / 4 * (d−σ) ²
X: Diameter corresponding to one pixel or length of one side of a square corresponding to one pixel (mm) in the visual field of the monitoring device
Ls: Average density of imaging of spitting (molten iron particles) Lt: Density threshold value of imaging of spitting (molten iron particles) d: Average value of diameter of spitting (molten iron particles) (mm)
σ: Standard deviation of spitting (molten iron particles) particle size (mm)   The converter according to claim 5, wherein the controller controls an oxygen injection amount from an upper lance based on information analyzed by the analysis device.   The imaging device according to claim 5 or 6, wherein when imaging the falling spitting, the imaging is imaging the spitting falling at a position below a converter steel outlet hole. Converter blowing control device.   The converter for blowing blast furnace according to any one of claims 5 to 7, wherein the imaging device is installed outside a range where spitting scattered from a converter furnace port falls.

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