JP2002285211A - Method for estimating coke filling structure at furnace hearth part of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for estimating a coke filling structure at a furnace hearth part of a blast furnace with residual pig iron quantity and residual slag quantity in the furnace can be decided at more accurate than the conventional method, in order to realize, what is called, 'dry-hearth' needed to the keep of the stable operation in the blast furnace. SOLUTION: When the structure of the coke filling layer the front part of a molten pig iron tapping hole in the furnace hearth part of the blast furnace is estimated, a ratio of the measured value of the slag quantity discharged during tapping the molten pig iron and a calculated value of the slag quantity produced in the furnace, is obtained, and the coke filling structure is estimated, based on the above ratio at the time point passing a prescribed time from the opening of the molten pig iron tapping hole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for estimating a coke filling structure in a blast furnace hearth, and more particularly, to a method for appropriately maintaining a coke filling structure in a hearth to enable stable blast furnace operation. And a technique for accurately grasping the coke filling structure.

[0002]

2. Description of the Related Art In a blast furnace, raw materials (iron ores and coke) are charged from the furnace top and deposited in layers, and high-temperature air blown from the lower part of the furnace burns coke in the furnace to generate high-temperature air. A reducing gas is generated, and while this high-temperature reducing gas rises in the furnace, the temperature of the raw materials deposited in the furnace and the reduction of ores,
Melting occurs and hot metal and slag flow down to the hearth. As described above, the ore is melted and disappears in the lower part of the blast furnace, so that a coke packed layer is formed.

[0003] Hot metal and slag flowing down to the hearth are discharged out of the furnace by opening a taphole provided in the hearth. In large blast furnaces constructed in recent years, this tap hole has 2 to 4 taps.
An operation of discharging the hot metal and slag flowing down to the furnace bottom by always opening and closing the tap holes as appropriate is performed.

FIG. 2 schematically shows a state in the furnace immediately after one of the tap holes is closed and the other is opened. As shown in FIG. 2, in the closed tap hole 1 on the right side, the liquid level positions 2 and 3 (hereinafter, referred to as levels) of the hot metal and the slag are the tap holes 1.
At almost the furnace inside height. This is because the taphole 1 was closed after the hot metal and slag were discharged until the gas in the furnace was ejected. On the other hand, in the tap hole 4 on the left side, which has just been opened, the slag level 3 is at a position considerably higher than the inside height of the tap hole 4 in the furnace. This means that the slag that has accumulated near the taphole on the left side does not flow much to the taphole side on the right side that was opened during the previous tapping. This is because there was resistance of the coke packed bed 5 and it was difficult for hot metal or slag to pass through the coke packed bed 5 from near the taphole on the left side to near the taphole on the right side. After the opening of the left tap hole 4, the hot metal or slag is gradually discharged from the left tap hole 4 to the outside of the furnace, and the levels 2 and 3 of the hot metal or slag decrease. However, since the blast furnace operation is continuous, new hot metal or slag is constantly generated and flows down to the hearth 6, so that newly generated hot metal or slag is near the right taphole on the opposite side. Accumulate and their level increases. As described above, the levels 2 and 3 of the hot metal and slag in the hearth 6 of the blast furnace alternately rise and fall near each tap hole according to the tapping time. Actually, the levels 2 and 3 of the hot metal and the slag in the furnace are determined by the balance between the flow of the hot metal and the slag in the furnace and the amount of the generated hot metal and the slag discharged outside the furnace.

In the blast furnace, the tuyere 7 shown in FIG.
Hot air is supplied into the furnace from the furnace to burn the coke and the pulverized coal simultaneously blown from the tuyere 7, and the iron ore charged separately from the furnace top using the generated CO gas;
Reduces and melts slag-forming agents, etc. to produce hot metal and slag. At this time, if the level 3 of the slag in the furnace rises and reaches the installation position of the tuyere 7, the slag undesirably causes tuyere melting. Even if the slag level 3 is not so high, if it is relatively high, the slag level will affect the flow of gas rising in the furnace, and the operation will often be unstable. Therefore, the level of molten iron or slag (usually referred to as residual iron slag in the furnace) at levels 2 and 3
Is preferably as low as possible. That is,
For stable operation of the blast furnace, it is important to reduce the amount of residual iron slag in the furnace.

However, the amount of hot metal remaining in the furnace has conventionally been calculated from the amount of hot metal and slag produced in the furnace during the period from the start of tapping to the closing, and the amount of hot metal and slag actually discharged from the taphole. And was determined by comparing. This is simply the difference between the amount of generated hot metal and slag and the amount of discharged slag, and does not give any information about the amount of residual iron slag in the furnace at the time of tapping. Therefore, there is a problem that even if an operation action is taken using the information, a stable operation of the blast furnace cannot always be maintained.

[0007]

In view of such circumstances, the present invention has realized a so-called "dry hearth" (reducing the melt in the hearth as little as possible) necessary for maintaining a stable operation of the blast furnace operation. Therefore, it is an object of the present invention to provide a method for estimating a coke filling structure in a blast furnace hearth portion, which can determine the amount of residual iron and the amount of residue in a furnace more accurately than before.

[0008]

SUMMARY OF THE INVENTION The inventor of the present invention considers that it is necessary to clarify the factors that determine the amount of residue in the hearth in order to achieve the above object. The purpose of this study was to clarify the relationship between the temperature and the amount of residual iron slag in the furnace.

First, a half-cylindrical model hearth as shown in FIG. 3 was manufactured. This model hearth is a 1/25 scale of a blast furnace with a hearth diameter of 10 m, and the front surface is formed of a transparent acrylic resin plate so that the interior corresponding to the hearth can be observed. I have. Into the model hearth 8, plastic beads having a diameter of 6 mm were charged as pseudo coke to form a packed layer. This bead packing layer 9
The lower portion is supported by the wire mesh 20 to stabilize the shape of the filling layer, and the filling layer itself can be moved up and down. The reason why the whole of the bead packed layer 9 can be moved up and down is that in the actual blast furnace, the specific gravity of the coke is smaller than that of the hot metal. In the region 10 where the coke packed layer 5 does not exist (hereinafter, referred to as a region 10).
It is said that there is a free space 10).

In the model experiment, a specific gravity of 1.8 was set as pseudo hot metal.
Of liquid freon 11 and liquid paraffin 12 having a specific gravity of 0.8 as a pseudo slag are supplied from above the model hearth to a pseudo coke packed bed (also referred to as a bead packed bed 9) and provided on the lower left and right walls. It was carried out by discharging from the simulated taphole 13. Air 14 at a pressure of 30 kPa was supplied into the model during liquid supply by imitating gas in the furnace. In addition, the timing of switching the opening and closing of the pseudo tap hole 13 was based on the blowing of gas (in this case, air 14) as in the actual blast furnace. That is, the liquid Freon 11 and the liquid paraffin 12 are discharged from the pseudo tap hole 13, and when the upper surface 21 of the liquid paraffin 12 is lowered to the level of the pseudo tap hole 13, the air 14 is discharged from the pseudo tap hole 13. Therefore, the opening and closing of the pseudo tap hole 13 were switched at the timing when this phenomenon occurred.

FIGS. 4A and 4B show examples of the experimental results. This is because, as shown in FIG. 4B, the bead-filled layer 9 in the hearth is gradually lifted, and the upper end position of the free space 10, that is, the boundary position between the bead-filled layer 9 and the furnace wall is variously changed. Next, the results of an investigation on the amount of residue (slag) in the simulated hearth will be described. The boundary position was changed by setting the center line position 13a of the pseudo tap hole 13 to 0 and moving the entire bead-filled layer 9 up and down. The residue ratio was determined as 0% when no pseudo slag was accumulated above the tap hole level, and 100% when pseudo slag was accumulated up to 40 mm above the pseudo tap hole 13. 4A, when the upper end position of the free space 10 is low (H = −40 mm), the amount of the residue is large, but the lower end of the furnace wall of the bead packed layer 9 is lifted up to above the pseudo tap hole 13 and free. If the upper end of the space 10 is raised, (H
= + 20, +40, +80 mm), and a new finding that the amount of residue is reduced was obtained.

When the bead-filled layer 9 exists inside the furnace of the pseudo tap hole 13 (see FIG. 5A), gas is blown out before the pseudo slag is sufficiently discharged. It was necessary to switch the pseudo tap hole 13 left and right. This is because the resistance of the bead filling layer 9 was large, and the pseudo slag (arrow C) did not easily flow through the inside. On the other hand, when the free space 10 exists inside the furnace of the pseudo taphole 13 (see FIG. 5B), a phenomenon in which the pseudo slag in the furnace is significantly reduced was confirmed. This means that an annular flow (arrow D) of pseudo slag selectively flowing through the free space 10 inside the furnace of the pseudo taphole 13 is generated, and the pseudo slag is radially (arrow E) from inside the bead packed layer 9. This is for flowing into the annular flow. That is, in the bead filling layer 9,
It is considered that the pseudo slag flow is dispersed and the linear velocity is reduced, so that the resistance is reduced and the pseudo slag flows easily.

As described above, when the coke packed bed of the hearth floats due to buoyancy from the hot metal and forms a free space without a coke packed bed in front of the tap hole inside the furnace,
It turns out that the amount of residual iron slag in the furnace is small. Therefore, in the actual operation of the blast furnace, it is necessary to estimate the presence or absence of free space inside the taphole furnace, and when it is deemed that there is no free space, take active action to form free space. Can be considered.
The present invention has been made by intensive studies from this viewpoint.

That is, according to the present invention, when estimating the structure of a coke packed bed in front of a tap hole in a blast furnace hearth, the measured value of the amount of slag discharged during tapping and the amount of slag generated in the furnace Estimating the coke filling structure in the blast furnace hearth characterized by determining the coke filling structure based on the value of the ratio at the time when a predetermined time has elapsed since the opening of the taphole, Is the way.

In this case, assuming that the period from the opening of the tap hole to the gas blowing is 100% as the predetermined time, the time from the opening of the tap hole to the passage of some time of 10 to 50%. It is preferable that

When the ratio is more than 0.7, it is preferable that there is a coke packed bed in front of the taphole, and when the ratio is 0.7 or less, there is no coke packed bed.

According to the present invention, the presence / absence of the free space in the hearth can be determined based on the change over time in the amount of slag discharged from the taphole. As a result, the amount of residual iron slag in the hearth can be reduced, and stable blast furnace operation can be maintained.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in accordance with the circumstances leading to the invention.

In the above-described model experiment, the difference in the discharge of tapping slag depending on the presence or absence of free space before the taphole on the hearth was examined. In the model experiment, the packed bed of the model hearth was constructed as shown in FIGS. 1 (a) and 1 (c). FIG. 6 shows the result in the case corresponding to FIG.
FIG. 6A shows the result in the case corresponding to FIG.
(B). In FIG. 6, the horizontal axis represents time (unit: s).
ec), and the vertical axis is the flow rate of the standardized pseudo hot metal or pseudo slag shown below.

Here, the standardized flow rate of the simulated hot metal is defined as the denominator being the flow rate of the simulated hot metal supplied to the model per unit time, and the amount of the simulated hot metal discharged from the simulated tapping port being a numerator. This is a dimensionless number. According to this definition, when the standardized flow rate of pseudo hot metal is 1, it indicates that the amount of pseudo hot metal supplied is equal to the pseudo hot metal amount discharged from the tap hole, and when the flow rate exceeds 1, it is supplied. If the amount of simulated hot metal discharged from the tap hole is larger than the amount of simulated hot metal that has been dropped and is less than 1, it indicates that the amount of simulated hot metal supplied is greater than the amount of simulated hot metal discharged from the tap hole. . That is, the increase or decrease of the pseudo hot metal amount in the model is determined based on 1. In addition, this definition, with respect to the standardized flow rate of the pseudo slag, the denominator is the flow rate of the pseudo slag supplied to the model per unit time, and the numerator is the amount of the pseudo slag discharged from the pseudo taphole during that time. It is similarly used as a numerical value.

Next, the experimental results will be described with reference to FIG.
(A) shows that there is no free space in front of the simulated taphole, there is a coke packed bed, and the simulated slag in the model hearth is changing over time during tapping, and FIG. 6
(B) shows that there is a free space in front of the simulated taphole, there is no coke packed bed, and the amount of simulated slag in the model hearth changes with time during tapping with a relatively small amount. I have. Also, in any state, the way of discharging pseudo-hot metal and pseudo-slag has a noticeable fluctuation immediately after opening the taphole, but after the fluctuation has subsided, each has its own characteristics. Emission behavior. 6 (a) and 6 (b), the pseudo hot metal is relatively stable and the flow rate changes with time around 1 and the flow rate of the pseudo hot metal in the model hearth becomes substantially constant. ing.

However, when paying attention to the discharge of the pseudo slag, the discharge state greatly differs depending on the presence or absence of the free space. That is, in the state where there is no free space in FIG. 6 (a), the pseudo slag is relatively smoothly discharged from the beginning of the opening of the pseudo taphole, and the standardized flow rate is 0.7% for most of the period. It has been exceeding.
Then, in the latter half of tapping, the flow rate gradually increases and the gas flows out, showing a temporal change. On the other hand, FIG.
In the state with the free space (b), the discharge of pseudo slag was small at the beginning of the opening of the pseudo tap hole, and the standardized flow rate remained below 0.7, and then the pseudo slag flow increased rapidly. Over time, leading to gas blowing. Speaking of tapping control in a conventional blast furnace, in the case of FIG. 6 (a), the amount of slag to be generated and the amount of slag to be discharged are almost the same, so that good tapping slag However, as a result of the model experiment, such a slag discharge behavior indicates that the amount of residue in the furnace is large. In addition, the slag discharge behavior as shown in FIG. 6 (b) indicates that the amount of slag discharged is smaller than the amount of slag generated for a while after the start of tapping, according to the criterion in the conventional blast furnace operation. Therefore, it is not preferable, but in the model experiment, this results in a lower amount of the residue in the furnace. FIGS. 1A and 1C schematically show changes in the slag level in the furnace at the time of gas blowing in the model experiment. Similarly to these, examples showing changes in the slag level in FIG. In the case of the filling structure of the pseudo coke in the furnace shown in (a)), the pseudo slag layer thickness in the furnace at the time of gas blowing is large, and the transition shown in FIG. 6B (ie, FIG. 1C)
In the furnace pseudo-coke filling structure shown in (1), the thickness of the pseudo-slag in the furnace during gas blowing is small, and the amount of residue in the furnace can be reduced. Also, in the observation of the slag level in the furnace during the experiment, FIG.
It was found that the maximum slag level during tapping was larger in the example of (b). As described above, the difference between the judgment in the conventional actual blast furnace and the judgment in the model experiment is that under the condition where there is a large amount of residue as shown in FIG. 6 (a) in the model experiment, the slag layer thickness is large. The pressure is high and slag is relatively easy to be discharged from the beginning of tapping. On the other hand, under the condition where there is little residue as shown in FIG. 6B, the slag at the beginning of tapping is relatively discharged because the head pressure of the slag is small. It is assumed that the slag discharge is promoted when the slag layer becomes thick to some extent. However,
The model experiment is a result of forming an ideal situation, and is considered to be highly reliable.

By repeating the above model experiments and examining the discharge behavior of pseudo slag and hot metal with and without free space inside the furnace, it was found that the pseudo tap hole was opened to some extent after opening. Until the time has passed,
The discharge flow rate of pseudo-slag and pseudo-hot metal may fluctuate experimentally, but after the fluctuating time has passed and the tapping slag has stabilized, it should show almost the same transition depending on the presence or absence of free space. I understood.

That is, after the tapping slag is stabilized, the flow rates of the pseudo hot metal and the pseudo slag increase with the passage of time almost steadily or monotonously regardless of the presence or absence of the free space inside the pseudo taphole furnace. Thus, the flow rate does not tend to decrease. In addition, when there is free space, the flow rate is 0.7 or less when the tapping slag is stabilized, and after this state continues for a while, the slag flow rate sharply increases in the latter half of tapping, leading to gas blowing. . On the other hand, when there is no free space, the flow rate exceeds 0.7 when the tapping slag is stabilized, and the slag flow rate gradually increases in the latter half of tapping after the flow rate has changed for a while, and gas blowing Leads to.

Therefore, the inventor estimates the presence of the coke packed bed before the tap hole based on the standardized flow rate of the slag at the time when a predetermined time has elapsed from the start of tapping from the knowledge of these model experiments. That is the present invention. In this case, the predetermined time is a time after a period in which the flow rates of the hot metal and the slag after the tap hole is opened are not stable. When the period from the opening of the taphole to the gas blowing is 100%,
Until about 10% elapses, the flow of the molten iron slag in the furnace is unstable. On the other hand, if the time exceeds 50%, a rapid increase in the slag flow rate may be observed due to an increase in the slag layer thickness in the furnace, which is not preferable. Therefore, as the above-mentioned predetermined time, when the period from the opening of the tap hole to the gas blowout is 100%, 10 to 10
It is preferable to set the time until some point of 50% elapses. In addition, the standard of slag standardized flow rate is 0.7
If it exceeds this, it is determined that there is no free space before the tap hole (there is a coke packed bed). No).

In order to apply the present invention to actual blast furnace tapping, it is possible to record the standardized slag flow rate in a computer. The standardized slag flow rate in actual blast furnace tapping can be obtained as follows.

In an actual operation, the standardized slag flow rate can be defined as the amount of slag generated per unit time from the tap hole of the slag per unit time with respect to the amount of slag generated per unit time.

In this case, the amount of slag generated per unit time at an arbitrary point in time may be, for example, 10 charges from the arbitrary point in time for the past 10 charges of the furnace top charge (ore and coke). The amount of slag (for example, tons) generated from the charged raw material for each charge is calculated, and the resulting value is divided by the time (for example, for minutes) required for charging the 10 charges. It is convenient to calculate in units. At this time, if pulverized coal, heavy oil, waste, etc. are being injected from the tuyere,
The amount of slag generated per unit time at an arbitrary time point is obtained by adding the amount of slag generated from the blown object based on the amount of various blown objects at the time required for charging the charge. In this case, the number of charges to be included in the calculation is not limited to 10 charges, and any number of charges can be considered. Not preferred. Also, if you consider long-time charging that exceeds 15 charges,
You will be affected for a long time by changing the charged materials, etc.
It is not preferable because it causes a calculation error. Therefore 3 ~
The amount of slag generated during a period of about 15 charges may be included in the calculation.

On the other hand, the amount of slag discharged from the tap hole per unit time is calculated, for example, when the granulated slag is produced by guiding the slag discharged from the tap hole with a gutter. The approximate discharge amount can be calculated by recording the production amount of the granulated slag per unit time using a weighing device provided on a conveyor for transporting the crushed slag or the like. Alternatively, when slag is received from a gutter to a slag pot, the capacity of the pot is known. The amount of discharge from the pig iron can be determined.

Therefore, for example, when granulated slag is produced, the slag production amount Sa (ton / min) in a weighing device provided on the transport conveyor is determined, for example, every 15 minutes from the start of tapping. By calculating the slag generation amount Sc (ton / min) by dividing the slag generation amount in the past 10 charges at this time by the time required for the 10 charges, the standardized slag flow rate S at this time is S = It can be obtained as a dimensionless number as Sa / Sc.

Such calculations are performed every 15 minutes from the time of tap hole opening, and the time on the horizontal axis and the standardized slag flow rate on the vertical axis are recorded. The change of the standardized slag flow rate during the opening time can be read, and it can be determined whether or not the standardized slag flow rate exceeds 0.7 when 15% has elapsed since the start of tapping. .

When slag is received from a gutter to a slag pot, each time the slag pot receives one cup, the amount of the full pot and the time required for the reception are calculated per unit time. The amount of slag discharged from the taphole and the amount of slag generated at the time of completion of discharge are obtained in the same manner as described above, so that the standardized slag flow rate S at this time can be obtained by the same formula. .

In order to form a free space without a coke packed layer in front of the tap hole inside the furnace, the lower end of the core coke layer 5 only needs to be raised near the front of the tap hole inside the furnace. it is conceivable that. The lower end position of the core coke layer 5 on the hearth 6 side can be determined by the balance between the load applied to the core coke layer 5 from above and the buoyancy received from the molten iron slag in the furnace. Since the coke consumed in the tuyere 7 moves to the tuyere 7, this coke movement also affects the lower end position of the core coke layer 5 around the furnace wall. In other words, the tuyere 7
Space formed in front of the vehicle (referred to as raceway 16)
Is made of coke filled in the furnace, and the coke separated from the wall burns while turning inside the raceway 16. This peeled coke is supplied from the upper surface or the side surface of the wall of the raceway 16 and corresponds to coke existing above the tuyere position. On the other hand, the coke supplied from the lower wall of the raceway 16 is considered to have risen from below the raceway 16. The coke forming the core coke layer 5 in the hearth moves toward the upper tuyere 7 in the vicinity of the furnace wall, and the lower end position 15 of the core coke layer 5 in the furnace hearth is It is relatively low at the center, high at the furnace wall, and convex downward (see FIG. 7). The amount of movement of the coke toward the tuyere above the furnace wall is determined by the amount of coke consumed in the raceway 16 located in front of the tuyere 7 inside the furnace. When the blowing amount and the enriched oxygen amount in the blowing conditions of the tuyere 7 are controlled independently of the tuyere 7 provided at other positions and selectively increased, the vicinity of the tap hole It is thought that it is possible to raise the lower end position of the furnace core coke layer 5 by the above. This is the balance between the rising speed of the bottom of the core coke layer and the falling speed of the slag liquid level in front of the tap hole inside the furnace.If the rising speed of the bottom of the core coke layer is greater, This means that a free space can be secured inside and forward.
Here, the tuyere 7 provided immediately above the taphole is defined as two to four feathers on the vertical plane including the center axes of the tapholes 1 and 4 on either side of the center axis. Say mouth.

Further, as described above, the lower end of the core coke layer near the front of the taphole inside the furnace is located above the new coke that supplements the combustion consumption of coke in the raceway 16 above the taphole position. Because of the influence of the movement, the greater the depth of the raceway 16, the greater the amount of movement of the coke, and the higher the lower end of the coke layer toward the center of the furnace in front of the taphole inside the furnace, that is, the larger free space 10 Can be formed. This is because if the raceway 16 is deep and deep, coke is consumed deeply toward the center of the furnace, and the coke below it is encouraged to rise (see FIG. 8).

By utilizing this phenomenon, the depth of the raceway 16 formed by the tuyere immediately above the taphole is increased, so that the free space 10 near the front of the taphole inside the furnace is enlarged and maintained. To do it. For this purpose, the diameter of the airflow blown into the furnace from the tuyeres 7 provided immediately above the tapholes 1 and 4 is made larger than the diameter of the airflow blown from the tuyeres provided at other positions. You just need to increase it. Specifically, the diameter of the tuyere provided immediately above the tapholes 1 and 4 is larger than the diameter of the tuyere provided opposite the taphole, or a tuyere whose side wall is freely expandable and contractible is used. According to the study of the inventor, the degree of the diameter increase of the air flow is preferably 1.05 to 1.4 times. If the enlargement ratio is less than 1,05, it is almost the same as the error of the air volume of each tuyere, and it cannot be distinguished from the tuyeres provided at other positions. When the tuyere diameter is increased by more than 1.4 times, the area of the enlarged tuyere becomes about twice as large as the tuyere provided at other positions, and the air volume balance in the circumferential direction of the entire blast furnace Collapses, which is not preferable. In order to reliably exert the effect and to stably maintain the balance of the air volume in the circumferential direction of the entire blast furnace, an enlargement ratio of about 1.1 to 1.3 times is more preferable.

The tuyere 7 provided just above the taphole
Enlarging the diameter of the tuyere at other positions does not affect the stability of the blast furnace operation, that is, changing the production volume and the air volume and air temperature as operating conditions This is a very effective means because it increases the raceway depth of the tuyere located just above the taphole.

[0037]

EXAMPLE The present invention was applied to a blast furnace having an inner volume of 5000 m ³ . First, the tap hole was switched, and the standardized slag flow rate according to the present invention was measured and recorded at the tapping at the fifth tap after the start of use. At that time, the slag flow rate was obtained by estimating the amount of slag from the amount of granulated slag generated in the granulating equipment, and the amount of slag generated was calculated by the simulation model. FIG. 9 shows their ratio, that is, the standardized change in the slag flow rate over time. The tapping time (the time from the opening of the taphole until the gas blowing was recognized and the taphole was closed) was about 4 hours, but after the taphole was opened, the tapping slag was stable. When it was determined that about 15% of the tapping time had elapsed, the standardized slag flow rate was over 0.7. Therefore, in this tap hole, it is determined that free space has not yet been formed near the front of the tap hole inside the furnace,
The tuyere diameters of the two tuyeres located immediately above and near the taphole are 1
From 40 mmφ to 160 mmφ, the amount of oxygen blown into the furnace from the tuyere was increased, and the operation was continued.

As a result, in the next tapping, as shown in FIG. 10, the standardized slag flow rate associated with tapping becomes
A value less than 0.7 was recorded when about 15% of the stable tapping time of the tapping slag was reached, and the discharge pattern changed to an abrupt increase in the flow rate before gas blowing. This allows
It was determined that free space was formed inside the taphole furnace.

[0039]

As described above, according to the present invention, it is possible to determine the presence or absence of free space in the hearth based on the change over time in the amount of slag discharged from the taphole. As a result, the amount of residual iron slag in the hearth can be reduced,
It has become possible to maintain stable blast furnace operation.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view for explaining an effect when a free space is formed in front of a taphole inside a furnace, where (a) shows an angle θ = 180 ° at which a coke packed bed covers the taphole, and (b) shows an angle. θ = 1
5 ° and (c) show the case where θ = 0 °.

FIG. 2 is a schematic sectional view showing a lower part of a blast furnace.

FIG. 3 is a view showing a half-cut cylindrical model of a hearth section.

FIGS. 4A and 4B are diagrams showing the results of a model experiment, in which FIG. 4A is an explanatory diagram of the experimental results and FIG.

5A and 5B are diagrams for explaining the reduction of the amount of residue due to the generation of an annular flow of pseudo slag, wherein FIG. 5A shows a case where the front of the pseudo tap hole is completely covered with coke, and FIG. This is a case where a free space is formed in front.

FIG. 6 is a diagram showing a temporal change of a standardized flow rate (ratio of discharge flow rate / supply flow rate at a model hearth), which is the basis of the present invention, and (a) shows a free flow in front of a taphole; When there is almost no space, (b) is a case where there is a free space in front of the tap hole.

FIG. 7 is a diagram illustrating a relationship between a sedimentation speed of a furnace core coke layer and a coke consumption speed at a tuyere tip.

FIG. 8 is a diagram illustrating the formation of a free space near a furnace wall.

FIG. 9 is a diagram showing a change over time of a standardized slag flow rate when there is no free space in an actual blast furnace.

FIG. 10 is a diagram showing a change over time of a standardized slag flow rate when there is a free space in an actual blast furnace.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Tap hole 2 Hot metal liquid level (level) 3 Slag liquid level (level) 4 Left tap hole 5 Coke packed bed (core coke) 6 Furnace floor 7 Tuyere 8 Model furnace floor 9 Bead filled layer (beads) 10 Region where coke packed layer does not exist (free space) 11 Liquid Freon 12 Liquid paraffin (pseudo slag) 13 Pseudo tap hole 13a Tap hole center position 14 Air 15 Lower end position 16 Raceway 17 Mud Material 18 Taphole brick 20 Wire mesh (lower end of bead filling layer) 21 Upper surface of pseudo slag 22 Upper surface of pseudo slag

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Ken Sato 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Technical Research Institute of Kawasaki Steel (72) Inventor Shiro Watanabe 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Engineering Co., Ltd. (72) Yoshitaka Sawa Inventor 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Kawasaki Steel Co., Ltd. Address Kawasaki Steel Corp.

Claims (3)

[Claims] When estimating the structure of a coke packed bed in front of a taphole in a blast furnace hearth, the measured value of the amount of slag discharged during tapping and the calculated value of the amount of slag generated in the furnace A method for estimating a coke filling structure in a blast furnace hearth, wherein a ratio of the coke filling structure is determined based on a value of the ratio at a point in time when a predetermined time has elapsed from the opening of the taphole. 2. The method according to claim 1, wherein the predetermined time is defined as 100% of the period from the opening of the tap hole to the gas blowout until the passage of any time of 10 to 50% from the opening of the tap hole. The method for estimating a coke filling structure in a blast furnace hearth according to claim 1, wherein the time is time. 3. The method according to claim 1, wherein when the ratio exceeds 0.7, there is a coke packed bed before the taphole, and when the ratio is 0.7 or less, there is no coke packed bed. Or 2
The method for estimating the coke filling structure in the blast furnace hearth described above.