JPH0619092B2 - Blast furnace tap opening timing determination method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of use> The present invention relates to management of tapping work in a reactor using a blast furnace and a coke packed bed, and more particularly to a method for determining the opening time of tapping taps.

<Prior art> In the tapping work of a blast furnace, it is essential for stable operation of the blast furnace to accurately grasp how much molten pig iron is accumulated in the furnace. In particular, in the recent large-sized blast furnace, there is a strong demand for reducing the number of tapping for the purpose of improving productivity, reducing the basic unit of refractory for closing the taphole, or reducing the number of personnel in front of the furnace. In order to meet this requirement, it is essential to fully understand the level of molten pig iron slag before tapping. That is, if the tapping is started after the level of the molten pig iron is excessively high, the level change until the end of the tapping is too large and slips frequently occur, which impairs the stability of the operation. Conversely, if tapping is started when the level of molten pig iron is excessively low, tapping must be finished with a small amount of tapping, and the number of tapping increases, which serves the purpose of reducing the number of tapping. Can't do it.

Conventionally, the amount of molten pig iron (remaining amount of pig iron) accumulated in the furnace has been calculated and understood from the material balance. For example, the literature (“Sakai No. 2
Iron and steel management in blast furnaces "Iron and Steel 1986 S864), the amount of molten pig iron produced in the furnace was calculated from the number of times of charging, and the difference between the amount of molten pig iron actually produced and the amount of molten pig iron produced was calculated. It has been managed as the amount of residual slag. However, with this method, it was difficult to grasp the amount of accumulated residual slag in the long term because the measurement error of the actual amount of slag produced was large. In addition, when considering the effect on blast furnace operation, due to various factors such as the state of coke in the hearth and the decrease in hearth internal volume due to the formation of a furnace low solidification layer,
The influence of the amount of residual iron in the furnace on the operation of the blast furnace is not the same. That is, even if the amount of residual slag can be accurately estimated,
Since the level of molten pig iron in the blast furnace can be changed by the various factors mentioned above, it is possible to accurately estimate the molten pig iron level, which is an instruction to start tapping in a large blast furnace, by such a method. Is difficult.

A method disclosed in Japanese Examined Patent Publication No. 55-43046 is known as a method of indirectly grasping the level of hot metal in the furnace. He found that the tuyere brightness gradually became brighter at the end of tapping, and he attached a luminance meter to the tuyere and tried to use it as an index for tapping opening. However, this method is a method for determining the end time of tapping, and does not disclose the change in the brightness of the tuyere at an important time before the start of tapping.
Moreover, the change in tuyere brightness synchronized with tapping, which is shown in the prior art, has not been observed in a large blast furnace having an internal volume of 2000 m ³ or more.

In a large-scale blast furnace, it is important to determine the tapping start time in order to carry out tapping work without adversely affecting the operation of the blast furnace while reducing the number of pig irons per day.

The conventional technology cannot obtain effective information for determining the tapping start time.

<Problems to be Solved by the Invention> The present invention provides a more accurate method for determining the tapping start time in order to overcome the above-mentioned problems and perform an operation to reduce the tapping frequency in a large blast furnace. It was made to do.

<Means for Solving Problems> The present inventor uses a pre-tuyere brightness measuring device in a large blast furnace to determine the relationship between the temporal change in the brightness of the pre-tuyere raceway portion and the level of residual slag in the furnace. As a result of examination, it was found that there was a correlation between the two, and the present invention was completed based on this finding.

The present invention, when determining the opening time of the taphole in blast furnace operation, measures the brightness of the raceway part in front of the tuyere through one or more tuyere, and the brightness increases after the previous tapping is stopped. When the reference brightness increase amount ΔTs is reached or exceeded, the method for determining the opening time of the blast furnace tap hole, characterized in that the tap hole is opened, in the method according to the paragraph,
A method for determining the opening time of a blast furnace taphole, characterized in that a reference brightness increase amount ΔTs is set within the range of the following formula.

Record However, ΔTmax: maximum allowable brightness, : Expected value of increase rate of brightness after tapping opening, Δt ₂ : Expected value of time from start of tapping until brightness reaches peak value <Operation> Configuration of tuyere brightness measuring device used in the present invention The figure is shown in FIG. A brightness detection device 5 for measuring the brightness in the raceway 2 formed in front of the tuyere 1 is installed at the rear end of the blow pipe 8 via the sluice valve 3. The brightness detecting device 5 and the sluice valve 3 are connected via the optical fiber 4 with ease in mounting and dismounting and within a mounting accuracy (deviation in the axial direction) of ± 0.2 °. The brightness obtained by using this brightness meter is converted by the converter 6
Is converted to a temperature by using and is used as the raceway temperature. A typical pattern of the change with time is shown in FIG. The brightness before the tuyere shows a nearly constant value during the last stage of tapping and for a while after tapping. Normally, the opening work of the taphole is performed next time while the constant tuyere brightness is shown, and thus the change in the tuyere brightness in synchronization with tapping is not observed. However, in order to reduce the number of tapping, which is the object of the present invention, it is necessary to carry out opening work and continue tapping for a long time after the level of molten pig iron in the furnace rises after tapping is stopped. At this time, it was experimentally clarified that the change in the tuyere brightness appears as shown in FIG. 1 with the change in the residual iron content in the furnace. After showing a constant value for a while after tapping, the tuyere brightness begins to rise when the residual iron content in the furnace is at a constant value C ₀ or higher. When tapping is started on the way, the amount of residual iron in the furnace begins to decrease and at the same time the tuyere brightness also decreases. Tuyere brightness is
Even if the amount of residual iron in the furnace falls below a certain value C ₀ , it continues to decrease,
After reaching the minimum value, it returns to the original level for a short time. Such a change in brightness is considered to indicate the influence of the rise in the level of molten pig iron in the furnace on the coke descending speed to the tuyere and the gas flow in front of the tuyere. ³
Above) is a feature that appears only.

Since the limit value C _{0 of the} amount of residual slag that causes a change in brightness varies greatly depending on the operating conditions of the blast furnace, it is difficult to determine the tapping start time by the value of C ₀ .

When the relationship between the difference ΔTmax from the maximum brightness and the fluctuation of the operation (cumulative depth of slip (m)) that occurred at that time was examined based on the brightness when a constant brightness value was exhibited after the previous tapping was stopped. The results shown in Fig. 3 were obtained, and it became clear that the fluctuation of the operation could be made almost zero by setting ΔTmax <20 ° C. When the number of tapping cycles is reduced, ΔTmax is determined by the balance with the allowable fluctuation of the furnace condition. A specific method for managing ΔT will be described below with reference to FIG.

A time of Δt ₂ is required from the time of tapping to the time when the amount of residual slag begins to decrease. In order to control ΔTmax below a certain value, it is necessary to predict the change in ΔT of Δt ₂ and start tapping at a level ΔTs in advance. That is, the following relationship holds between ΔTmax and ΔTs.

By the way, it may take Δt ₁ (usually 10 to 20 minutes) from when the command for starting the tapping is issued until the tapping is actually started. In this case, expect a change in ΔT after the command to start tapping, and make ΔTs at the start of tapping, At, the command to start tapping should be issued.

Can be obtained from the change in ΔT as shown in FIG.

Depends on the tapping method, but in the case of lap tapping that opens two tapping holes at the same time, When using only one tap, Can be evaluated with. Therefore, when tapping using only one tap, By issuing the tapping start command at the stage when the tuyere brightness has reached the ΔTc calculated in step 1, the tapping work can be managed without adversely affecting the operation.

<Example> For a blast furnace having 30 tuyeres, a luminance meter for measuring the luminance of three tuyere located at equal positions in the circumferential direction was installed as shown in FIG. . As the luminance meter, a two-color pyrometer (temperature range 1400 to 2400 ° C) was adopted, and an optical fiber condensing method was adopted. Fiber diameter 250 for optical fiber
A bundle fiber was used in which 50 pieces of μm were bundled together.

FIG. 4 shows a typical example in which the output of the luminance meter is converted into temperature and the tapping start timing determined by the method of the present invention. In the measured values, very short cycle fluctuations (1 sec or less) due to the poaching into the tuyere, and long cycle fluctuations (5 min) that seem to be linked to the melting of the ore remain as noise. .

Therefore, in order to remove noise, noise filter 9 (noise removal for 1 sec or less) was applied to the output of the two-color pyrometer, and then data was input to the data processing procedure. FIG. 4 shows the value of this output. Long-term noise was removed by using a 10-minute moving average of the data to determine the change in ΔT.
50 ° C was set as ΔTmax, ΔTc was calculated on the premise of Δt ₁ = 10 minutes and Δt ₂ = 20 minutes, and the tapping start command was determined. This is shown as tapping start command ↓ in the figure.

The present invention is characterized in that the opening time of the taphole is determined by utilizing the change in the tuyere brightness as a means for reducing the number of tapping times in a large blast furnace without adversely affecting the operation. FIG. 5 shows a comparison of changes in the number of tappings and changes in the number of slips when the method of the present invention is applied. Although the number of times of tapping is large in period I when the tapping start time is determined by the conventional method,
The operation is also stable. During the period II, when the number of tapping was reduced without applying the method of the present invention, the operation became unstable, and the number of tapping was reduced by 0.5 times compared with the period I. Period III is the period when the method of the present invention is applied, and the number of tapping was able to be reduced by about 2.5 times compared to period I while maintaining the same operational stability as in period I. The reduction in the number of tapping times has great economic effects such as a reduction in the basic unit of mud material and a reduction in blast furnace and front personnel.

<Effect of the Invention> According to the method of the present invention, in the large blast furnace as described above,
The number of tapping operations could be reduced without adversely affecting the operation of the blast furnace, and the unit consumption of mud material could be reduced and the number of personnel could be reduced.

[Brief description of drawings]

FIG. 1 is a graph showing changes with time in front of tuyere brightness and the like, and FIG. 2 is an explanatory view of a front of tuyere brightness measuring device used in the present invention.
FIG. 3 is a graph showing the relationship between the luminance change parameter and the cumulative slip depth, FIG. 4 is a graph showing an example of the measurement result of the front tuyere luminance, and FIG. 5 is the presence / absence of implementation of the method of the present invention. 7 is a graph showing the relationship between the number of times and the slip frequency. 1 ... Tuyere, 2 ... Raceway, 3 ... Gate valve, 4 ... Optical fiber, 5 ... Luminance detection device, 6 ... Converter, 7 ... Data processing device, 8 ... Blow pipe, 9 ……Noise filter.

Claims (2)

[Claims] 1. When determining the opening time of the taphole in blast furnace operation, the brightness of the raceway part in front of the tuyere is measured through one or more tuyere, and the brightness is measured after the tapping was stopped last time. A method for determining the opening timing of a blast furnace tap hole, which comprises opening the tap hole when the increased reference brightness increase amount ΔTs is reached or exceeded. 2. A method according to claim 1, wherein the reference brightness increase amount ΔTs is set in the range of the following formula: Record However, ΔTmax: maximum allowable brightness, : Expected value of increase rate of brightness after tapping opening, Δt ₂ : Expected value of time from start of tapping until brightness reaches peak value