JP4416857B2 - Blast furnace output control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a blast furnace discharge control method when discharging the hot metal in the blast furnace together with the hot metal from the discharge hole.
[0002]
[Prior art]
Generally, in a blast furnace, coke, ore, etc. are introduced from above, and hot air is blown from a tuyere provided at the lower part of the kiln, so that a temperature rise similar to combustion occurs in a so-called raceway in front of the tuyere. This causes the ore to melt and flow down to the hearth as hot metal and hot metal. Hot metal is literally hot metal other than hot metal and is also called slag. Generally, hot metal accumulates below hot metal due to the specific gravity. Thus, the hot metal and hot metal (hereinafter also simply referred to as hot metal) stored in the hearth part of the blast furnace are discharged as the hot metal from the tap hole formed at the lower end of the furnace wall.
[0003]
As a conventional control method at the time of this discharge, there is a method described in Japanese Patent Publication No. 63-65730, for example. This prior art is to control the amount of air blown from the tuyere and the depth of the tap hole, for example, when the depth of the tap hole becomes shallow, by reducing the amount of air blown from the tuyere, The gas flow in the vicinity of the tap hole becomes inactive, slag adheres in the vicinity of the tap hole, and the depth of the tap hole becomes deep. In addition, at the end of the brewing process, gas blown out from the brewing hole, so-called stormy state, the level of hot metal stored in the hearth is reduced by reducing the amount of air blown from the tuyere. That is, the liquid level is stabilized and gas blowing can be suppressed. When the tapping operation is completed, a filler called mud is pushed into the tapping hole to close it.
[0004]
[Problems to be solved by the invention]
In the above conventional taping control method, when the taphole depth becomes shallow, the gas flow in the vicinity of the taphole becomes inactive by reducing the amount of air blown from the tuyere, and the slag in the vicinity of the taphole. When the depth of the tap hole becomes deeper and the depth of the tap hole becomes shallower, the flow of air from the tuyere increases to increase the gas flow in the vicinity of the tap hole. It is said that the slag in the vicinity of the fistula is peeled off, so that the depth of the spout is reduced. However, just because the air flow from the tuyere is changed, slag does not adhere to the vicinity of the tap hole or the slag does not peel off from it. There is nothing to do.
[0005]
In general, when the depth of the tap hole is shallow, the mud deposition layer covering the hearth is thin, and it is considered that the hearth is easily damaged by being exposed to high-temperature hot metal. Therefore, in such a case, the amount of mud used to be pushed in from the tap hole (this is referred to as mud pushing amount) is increased. In other words, if the state where the tap hole depth is shallow continues, even if the amount of air blown from the tuyere is reduced, the tap hole depth does not increase as it is, and the tap hole depth, that is, the mud deposition layer is deepened. Therefore, the amount of mud pushing tends to increase and the basic unit of mud tends to increase.
[0006]
It is an object of the present invention to provide a blast furnace output control method capable of reducing the amount of mud pushing and reducing the basic unit by controlling the degree of wear of the mud deposit layer covering the hearth. It is the purpose.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the blast furnace discharge control method of the present invention is the blast furnace discharge control method for discharging the molten iron in the blast furnace together with the molten iron from the discharge hole. The tuyere diameter above the hole is larger than the tuyere diameter of the other tuyere, and at least at the tuyere where the tuyere diameter is larger above the tap hole, a flow control valve is used to adjust the amount of hot air blown. Attire , Out By reducing the airflow from the tuyere above the fistula relative to the airflow from the other tuyere, the coke packed bed is brought closer to the mud deposit and the coke packed layer Make the space smaller By allowing the lower end of the coke packed layer to be buried in the mud deposited layer, or by ensuring that the mud deposited layer is covered and protected by the coke packed layer, The present invention is characterized in that it suppresses the wear of the mud deposit layer and reduces the amount of mud pushed in from the tap hole.
[0008]
Here, as will be described later, these inventions are in a space where hot metal and hot metal (hot metal) flow between the coke packed layer below the tuyere and the mud deposit layer where the spout hole is opened. It was made with attention. That is, if this space is large, the hot metal fluidity is improved, so that the wear of the mud deposit layer exposed to it is accelerated, and conversely if the space is small, the hot metal fluidity is lowered, or the mud deposit layer is coke. Since it is protected by the filling layer, wear of the mud deposit layer exposed to the hot metal is suppressed. This space can be adjusted by controlling either one or both of the coke packed layer and the mud deposited layer. Therefore, in the present invention, the state of the coke packed bed is controlled by controlling the increase and decrease of the air flow rate from the tuyere above the tap hole relative to the air flow rate from the other tuyere. Thus, the space between the coke filling layer and the mud deposition layer is adjusted. That is, the air flow rate from the tuyere above the tap hole is equal to or relatively less than the air flow rate from other tuyere, so that there is a gap between the coke packed bed and the mud deposit layer. This reduces the amount of mud deposits, which can reduce the amount of mud required to maintain the tapping depth, for example. It becomes possible to do.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of a method for controlling the output of a blast furnace according to the present invention will be described in detail with reference to the drawings.
First, in FIG. 1, the longitudinal cross-sectional view from the tuyere of the blast furnace of this embodiment to a hearth part is shown. A tuyere 2 as a hot air blowing port is provided at the lower part of the furnace wall 1 of the blast furnace over the entire circumference. The tuyere 2 is supplied with a gas heated to about 1000 ° C. in a hot air furnace (not shown), and the hot air blown out from the tuyere 2 into the blast furnace is called a raceway 3 in a coke packed bed 4 to be described later. A high heat space is formed.
[0010]
On the other hand, coke, ore, and the like charged from above the blast furnace form a coke packed bed 4 made of only coke below the tuyere 2. This is because the ore is melted by high-temperature heating in the raceway 3 and flows down to the hearth as hot metal and hot metal, that is, hot metal 9. Further, the hearth part is covered with a mud made of a refractory material to constitute a mud deposition layer 5. This mud is used to close the tap hole 7 drilled from the furnace wall to the mud deposition layer 5, and this mud deposition layer 5 protects the original hearth.
[0011]
When a certain amount of hot metal 9 accumulates on the hearth of the blast furnace, that is, on the mud deposition layer 5, it penetrates through the tap hole 7 from the furnace wall 1 to the mud deposition layer 5, and from the tap hole 7. The hot metal 9 is discharged as an output.
Next, an example of the layout of the tuyere is shown in FIG. In the blast furnace of this embodiment, three tap holes from the first tap hole 7 (a) to the third tap hole 7 (c) are used. On the other hand, a total of 33 tuyere 2 are provided in the furnace wall over the entire circumference. All the tuyere 2 are connected to a common hot air supply source so that sufficient hot air can be blown from any tuyere 2.
[0012]
In the present embodiment, the tuyere 2 (a) above each of the tapping holes, specifically, the first tapping hole 7 (a) is disposed so as to sandwich it. Fifteenth and sixteenth tuyere 2 (a), the third tapping hole disposed so as to sandwich the first and thirty-third tuyere 2 (a) and the second tapping hole 7 (b) The tuyere diameters of the 18th and 19th tuyere 2 (a) arranged so as to sandwich the hole 7 (c) are larger than those of the other tuyere 2 (b). Thus, the amount of air blown from the tuyere 2 (a) above the tap holes can be increased relative to the amount of air blown from the other tuyere 2 (b). However, for example, since there is basically only one tap hole 7 used for the taping operation, the amount of hot air blown into the tuyere 2 (a) having a large tuyere diameter above these tap holes. A flow control valve 8 is provided for adjusting the flow rate.
[0013]
Further, as will be described later, in the present embodiment, the air flow rate from the tuyere 2 (a) above the tap hole is relatively increased with respect to the air flow rate from the other tuyere 2 (b). Therefore, the layout of the tuyere 2 may be as shown in FIG. 3, for example. That is, the tuyere diameters of all tuyere 2 are set to be the same as the tuyere diameters of tuyere 2 (a) above the tap hole, and flow control valves 8 are interposed in all tuyere. Therefore, for example, if the airflow rate from the tuyere 2 (a) above the tap hole is increased relative to the airflow rate from the other tuyere 2 (b), The flow control valve 8 interposed in the tuyere 2 (a) may be opened and the flow control valve 8 interposed in the other tuyere 2 (b) may be closed. Conversely, for example, if the air flow rate from the tuyere 2 (a) above the tap hole is decreased relative to the air flow rate from the other tuyere 2 (b), The flow control valve 8 interposed in the tuyere 2 (a) may be closed and the flow control valve 8 interposed in the other tuyere 2 (b) may be opened. In addition, if the air flow from all tuyere 2 is made equal, the opening degree of the flow control valve 8 of all tuyere 2 may be made the same level.
[0014]
Next, the flow control valve provided in the tuyere will be described with reference to FIG. This flow control valve can withstand long-time use even at high temperatures, high pressures and high flow rates using ceramics as a valve body 8 a, and is connected to the extension 12 of the blower branch 11 and the blow pipe 13 in the tuyere 2. It is integrated with the spherical short tube 15 between the lower bend 14 for connection. The opening degree of the flow control valve 8 can be continuously changed manually or by an actuator, and the air flow rate characteristic is as shown in FIG. The air volume ratio is expressed as a percentage of the value obtained by dividing the air volume at each valve opening angle (opening) by the total air volume.
[0015]
Next, the principle of the output control method of this embodiment will be described.
First, the ideal for extending the output time while securing a stable output amount will be described with reference to the output amount characteristic diagram of FIG. That is, for example, if a stable amount of iron is expected, it is desirable that the amount of hot metal or hot metal that can be produced, that is, the amount of ironmaking is constant from the standpoint of blast furnace durability and material supply. Even in actual operation, the amount of ironmaking is made constant. In other words, for example, if the amount of ironmaking is to be increased, the furnace temperature must be raised, so that the durability of the furnace body is reduced, and the raw materials must also be supplied in an increased process. In contrast, a general output amount characteristic appears as shown in FIG. That is, when no operation is performed, the output amount increases in the latter stage of the output because the diameter of the output hole becomes larger due to wear due to heat as the output elapses. In order to bring the output time close to a certain amount of iron making and to extend the time of the ironing, it is necessary to reduce the initial ironing hole diameter. It will be less than the amount of drought. The output time can be extended by bringing the actual output amount close to the amount of iron formation, and can be extended significantly by stabilizing it.
[0016]
On the other hand, as described in Japanese Patent Publication No. 63-65730, the roughened state occurs at the end of the brewing because the amount of air blown from the tuyere is too high and the internal pressure increases. This is considered to be because the liquid level of the hot metal in the hearth portion is undulated, and therefore, when it is in a rough state, the amount of air blown from the tuyere is reduced to suppress gas blowing. However, in such a case, although the gas blowing is surely suppressed, the amount of brewing itself is also reduced, and the brewing operation is finished because a stable amount of brewing cannot be obtained. In other words, there has been a contradiction that, in the past, although the amount of air blown from the tuyere has been decreased in an attempt to increase the amount of brewing, the amount of brewing is substantially reduced. In addition, if the tuyere diameter itself is made small in order to reduce the amount of air blown from the tuyere in this way, there is also a problem that it is not possible to cope even if it is desired to increase the amount of air blown to increase production. The end of the tapping operation is performed by closing the tapping hole with mud.
[0017]
As a result of intensive studies on the contradiction, the present inventors obtained the following knowledge and developed the present invention. In other words, the fact that the amount of slag is small, that is, that the evacuation property is poor, means that the hot metal fluidity in the vicinity of the slag hole in the furnace is poor. Is low, or there is a resistance. Of these, in actual operation, the temperature of the hot metal is controlled to be almost constant, and the temperature of the output from the output hole with poor exhaustability is not always low. The amount of soot is the fluidity of the hot metal 9 in the space 6 between the coke packed layer 4 and the mud deposit layer 5 in the hearth portion where the hot metal is stored, for example, as shown in FIG. I found it involved. However, the space 6 includes not only a space between layers but also a space such as a gap between cokes that do not substantially form a layer. When this space 6 is large, the fluidity of the hot metal 9 is improved and the amount of slag is increased (exhaustability is improved). On the other hand, if the space 6 is small, the fluidity of the hot metal 9 is lowered and the amount of slag is reduced (exhaustability is lowered). With regard to this fluidity, as will be described in detail later, hot metal with a higher viscosity is more susceptible to influence, but if this space can be controlled anyway, the amount of output is free. It was found that it can be adjusted.
[0018]
The element constituting the space 6 is, of course, the relative positional relationship between the coke filling layer 4 and the mud deposition layer 5. For example, in FIG. 1, if the end portion of the coke filling layer 4 on the side of the tap hole can be displaced to a position indicated by a broken line, the space 6 between the mud deposition layer 5 is expanded. Conversely, even if the end portion of the coke filling layer 4 in the mud deposit layer 5 in the mud deposition layer 5 is displaced to the position indicated by the broken line, the space 6 between the mud deposition layer 5 and the coke filling layer 4 is expanded. Of these, the former can be achieved by increasing the air flow rate from the tuyere 2 (a) above the tap hole relative to the air flow rate from the other tuyere 2 (b). I understood. That is, if the air flow rate from the tuyere 2 (a) above the tap hole is increased relative to the air flow rate from the other tuyere 2 (b), the entire coke packed bed 4 is discharged. By trying to move away from the hole 7 or by compressing the coke packed layer 4 on the tap hole side so as to become dense, the end portion on the tap hole side of the coke packed layer 4 becomes the tap hole The space 6 between the mud deposit layer 5 and the mud deposit layer 5 becomes larger.
[0019]
For this reason, in the present embodiment, as shown in FIG. 2, the tuyere diameter of the tuyere 2 (a) above each tap hole is set larger than the tuyere diameter of the other tuyere 2 (b). The amount of air blown from the tuyere 2 (a) above the tap hole can be increased relative to the amount of air blown from the other tuyere 2 (b). As described above, it is desirable to stabilize the iron making in the furnace as much as possible as described above, and in order to protect the furnace body as will be described later, The amount of air blown from the tuyere 2 (a) above the hole needs to be equal to the amount of air blown from the other tuyere 2 (b). Furthermore, if the amount of mud used is to be reduced as will be described later, conversely, the amount of air blown from the tuyere 2 (a) above the tap hole is changed to the amount of air blown from the other tuyere 2 (b). On the other hand, there is a need to reduce the relative value. For this reason, in this embodiment, at least the tuyere 2 (a) above each tap hole is provided with a flow control valve 8, and the air flow rate is changed to the air flow rate from the other tuyere 2 (b). On the other hand, a relative increase / decrease adjustment is made possible.
[0020]
Further, since the relationship of the air flow rate between the tuyere is relative, for example, as shown in FIG. 3, the tuyere diameters of all tuyere 2 are shown above the tuyere in FIG. 2 (a) is equivalent to the tuyere diameter, and all tuyere 2 are provided with flow control valves 8, and as described above, the amount of air blown from tuyere 2 (a) above the spout hole at the time of tapping Is relatively increased with respect to the air flow rate from the other tuyere 2 (b), and otherwise, for example, the air flow rate from all the tuyere 2 is made equal, or the wings above the spout hole You may make it reduce the ventilation volume from the opening 2 (a) relatively with respect to the ventilation volume from the other tuyere 2 (b).
[0021]
On the other hand, in the latter, that is, in the mud deposition layer 5, it is not easy to displace the end portion on the coke filling layer 4 side at the portion of the tap hole 7. Therefore, in order to increase the fluidity of the hot metal 9 up to the tap hole 7, it is possible to simply reduce the tap hole depth, that is, to open the tap hole 7 at a position far from the coke packed bed 4. . However, in general blast furnaces, for example, the position and angle of opening of the tap hole are almost regulated due to the relationship of tapping and the like, and it is difficult to change the opening part of the tap hole. Therefore, when it is desired to increase the total amount of dredging, that is, in order to reduce the depth of the tap hole, the coke filling layer 4 side end portion of the mud deposit layer 5 in the tap hole portion is concerned. When it is desired to increase the space 6 between the layers 4 away from the layer 4, the amount of mud pressing for closing the tap hole 7 may be reduced. On the other hand, when it is desired to reduce the amount of brewing as a whole, that is, in order to increase the depth of the brewing hole, the coke-filling layer 4 side end portion of the brewing hole portion of the mud deposition layer 5 is filled with the coke. In order to approach the layer 4 and reduce the space 6 between them, the mud pressing amount may be increased.
[0022]
In addition, the amount of mud used, that is, the so-called basic unit can be reduced by combining these. That is, for example, as described above, the amount of air blown from the tuyere 2 (a) above the tap hole is increased relative to the amount of air blown from the other tuyere 2 (b), thereby filling the coke. When the space 6 between the layer 4 and the mud deposit layer 5 is enlarged to increase the fluidity of the hot metal 9, the mud deposit layer 5 is exposed to the hot hot metal 9 and the mud refractory in that portion is easily worn out. . Therefore, for example, when it is not necessary to increase the amount of tapping or when it is not during tapping, for example, the amount of air blown from the tuyere 2 (a) above the tapping hole is used as the other tuyere 2 (b). The amount of air blown from the slag is equal to or relatively decreased, and the mud deposition layer 5 at the spout hole 7 site is not easily exposed to the hot metal 9 having good fluidity, thereby suppressing its wear. be able to. Further, when the coke filling layer 4 is brought close to the mud deposition layer 5, the lower end portion of the coke filling layer 4 is buried in the mud deposition layer 5. If it becomes like this, the mud deposit layer 5 comes to be protected from the hot metal 9 by the coke filling layer 4, and the wear of the mud deposit layer 5 is further suppressed and prevented. Thus, when it is not necessary to increase the amount of tapping or when it is not during tapping work, for example, the amount of air blown from the tuyere 2 (a) above the tapping hole is used as the other tuyere 2 (b ) Or the relative reduction from that, the mud deposition layer 5 can be prevented from being worn and prevented, and the mud basic unit can be reduced while securing the tap hole depth. It becomes possible.
[0023]
Up to this point, it has been said that the space between the coke packed bed and the mud deposition layer described above affects the fluidity of the hot metal as a whole, but the size of this space is more affected by hot metal than hot metal. easy. This depends on the fact that the hot metal exists on the hot metal due to the specific gravity and that the hot metal has a higher viscosity than the hot metal. That is, by controlling the size of the space between the coke packed layer and the mud deposit layer, the balance between the rejectability and the rejectability, that is, the output balance can be controlled.
[0024]
As mentioned above, in the conventional tap control method for reducing the amount of air blown from the tuyere during the taping operation, the space between the coke packed bed and the mud deposit layer is reduced, particularly hot metal. On the other hand, while the fluidity of the metal is reduced and the evacuation property is deteriorated, the hot metal that is not affected by the size of the space is discharged more and more. Therefore, in this state, the hot metal operation is stopped, and the ratio of the hot metal stored in the hearth portion gradually increases as compared with the hot metal until the next hot metal. Therefore, when the brewing operation is repeated several times, the brewing balance is lost, and it is necessary to discharge a large amount of hot metal. For this reason, the above-described work of expanding the diameter of the wrap and the diameter of the tap hole is performed, and the hot metal in the furnace is discharged all at once. Therefore, there remains a problem that the number of times of output increases and the work load also increases.
[0025]
However, as described above, the space between the coke packed bed and the mud deposit layer has a greater influence on the hot metal fluidity than the hot metal fluidity. When the inertia is good and the evacuation property is poor, the amount of air blown from the tuyere above the spout hole is increased relative to the amount of air blown from the other tuyere, so that Not only can the amount be increased, but also the drainage can be improved and the balance of output can be brought closer to a desired state. On the other hand, for a desired balance, for example, when the evacuation property is poor and the evacuation property is good, the air flow rate from the tuyere above the brewing hole is changed to the air flow rate from the other tuyere. On the other hand, by relatively decreasing, not only the amount of output can be reduced, but also the evacuation property can be improved and the output balance can be brought close to a desired state. As described above, in this embodiment, by controlling the balance of output, a stable output amount can be secured for a long time for each output operation, and as a result, the number of output is reduced. You can lengthen the spawn time.
[0026]
Next, the operation of the output control method of this embodiment will be described using various experimental results.
FIG. 7 shows the diameters of the 18th and 19th tuyere above the third boring hole in FIG. 2 after the number of tapping times (Tap.No in the figure) is a. By increasing the diameter from φ120 mm, which is the tuyere diameter, to φ140 mm, and controlling the flow rate control valve except during tapping, the air volume from the 18th and 19th tuyere is changed to the air volume from the other tuyere The flow rate control valve is fully opened during the unloading operation from the third unloading hole, so that the air flow from the 18th and 19th tuyere is sent from the other tuyere. The air volume is increased about 1.5 times. In addition, as shown in FIG. 7c, the average output time x of the output operation before the a-th time ^- Is 191 minutes, average spawn time after the a-th x ^- Is 198 minutes, and the spawning time itself has not changed much.
[0027]
Here, the output state before and after the a-th time is compared using an evaluation index called a slag index. First, this slag index is the ratio of output time to output time (= output time / output time). Literary time is literally the time from opening a boring hole to closing it. The output time is the time from when output is accumulated to a certain level of output until the output hole is closed. In other words, the slag index can be thought of as evaluating the amount of output particularly at the initial stage of output, and the output amount characteristic at the initial stage of output is shown in FIG. It becomes an evaluation index as to whether or not the amount of drought can be approached. FIG. 7a shows a histogram of the slag index before the output number a times, and FIG. 7b shows a histogram of the slag index after the output number a times. From these, the frequency of high slag index is high after the number of times of brewing that has increased the air flow rate from the tuyere above the tap hole relative to the air flow rate from other tuyere. You can see that Here, when this slag index is large, it means that there is a large amount of output from the beginning of the output, so the output time itself can be shortened if considered normally. However, since the spout time has not shortened after the a-th spout, the air flow rate from the tuyere above the sprue hole is compared to the air flow rate from the other tuyere during the tapping operation. Thus, the relative increase increases the space between the coke packed bed and the mud deposition layer to increase the fluidity of the hot metal, thereby increasing the amount of output from the initial stage of the output. It can be seen that a high output ratio can be achieved by securing drought time.
[0028]
Next, FIGS. 8 to 13 show that the amount of air blown from the tuyere above the spout hole is equivalent to the amount of air blown from the other tuyere at the tapping number (Tap. No) 20 to 50th. At the 50th to 60th time of dredging (shaded area in the figure), the amount of air blown from the tuyere above the spout is reduced to about 30% of the amount of air blown from the other tuyere, and the number of spears After 60 times, each physical quantity and evaluation index when the air flow rate from the tuyere above the tap hole is returned to the same as the air flow rate from the other tuyere are shown.
[0029]
First, FIG. 8 shows the change of the aforementioned slag index for each output. As described above, when the amount of air blown from the tuyere above the tap hole is decreased relative to the amount of air blown from the other tuyere, the space between the coke packed layer and the mud deposit layer becomes small. Since the fluidity of the hot metal in the space is reduced, the amount of the output at the initial stage of the output is also reduced, and therefore the accumulation of the output to the predetermined level of the output is delayed. The slag index is small in the 50th to 60th mining. It can also be seen that this effect gradually appears. On the other hand, when the amount of air blown from the tuyere above the spout hole is made equal to the amount of air blown from the other tuyere at the 60th turnout, the slag index immediately increases. Therefore, it can be seen that the slag index has high responsiveness to the control for increasing the air flow rate from the tuyere above the tap hole.
[0030]
Further, FIG. 9 shows the output balance and FIG. 10 shows the output slag balance. The balance is a value obtained by subtracting the input amount from the amount discharged at each output. In other words, if the balance is a positive value, the discharged amount is larger than the input amount, so that the discharging property is good, and if the balance is negative, the discharging property is bad. As is clear from these, when the amount of air blown from the tuyere above the tap hole is relatively decreased with respect to the amount of air blown from the other tuyere, between the coke packed bed and the mud deposit layer, Since the space is small, the slag excretion which is greatly affected by the fluidity in this space is lowered, and the excretion which is not so affected is relatively improved. Further, in this embodiment, when the amount of air blown from the tuyere above the spout hole is made equal to the amount of air blown from the other tuyere, the soot balance and slag balance are balanced in the vicinity of zero. On the contrary, if the air flow rate from the tuyere above the tap hole is relatively increased with respect to the air flow rate from other tuyere, the evacuation property is improved and the evacuation property is relatively improved. Is expected to decline.
[0031]
Next, FIG. 11 shows changes in the output time for each output time. Along with the changes in the slag index and the evacuation balance as described above, the state where it is difficult to brew continues at the 50th to 60th brewing, and the brewing time tends to be shortened as a whole. Considering this and the slag balance, conventionally, in the control for reducing the air flow rate from the tuyere above the tap hole relative to the air flow rate from other tuyere, It is understood that the hot metal was accumulated every time the work was performed, and eventually the hot metal in the furnace had to be discharged all at once due to the lapping and the diameter expansion of the tap hole.
[0032]
Next, FIG. 12 shows changes in the tap hole depth, and FIG. 13 shows changes in the tap hole depth per unit mud pressing amount. FIG. 12 shows that the pit depth was not changed intentionally, and FIG. 13 shows that the pit depth per unit mud increases with respect to the pit depth not changed. As a result, the mud pushing amount used as a result gradually decreases. That is, as described above, when the air flow rate from the tuyere above the tap hole is decreased relative to the air flow rate from the other tuyere, the space between the coke packed layer and the mud deposit layer is reduced. The mud deposit layer becomes less exposed to the hot metal or becomes protected by being covered with the coke filling layer, so that the mud deposit layer is less likely to be worn out, and the spout hole is reduced by that much. The amount of mud used when closing is small. In addition, this effect gradually appears. On the other hand, when the amount of air blown from the tuyere above the tap hole is made equal to the amount of air blown from the other tuyere, the tap hole depth per unit mud pushing amount immediately decreases, so the coke It can be seen that the responsiveness of the wear of the mud deposition layer is high when the space between the filling layer and the mud deposition layer becomes large.
[0033]
Considering this in reverse, for example, increasing the amount of brewing in a state where the amount of air blown from the tuyere above the taphole is not intentionally changed with respect to the amount of blasted air from the other tuyere. When it is desired to do so, the space between the coke packed layer and the mud deposit layer may be increased. In such a case, the mud pressing amount may be decreased to reduce the depth of the tap hole. On the other hand, when it is desired to reduce the amount of tapping, the amount of mud pressing may be increased in order to reduce the space between the coke filling layer and the mud deposition layer and increase the tapping depth.
[0034]
Next, FIG. 14 shows changes after the air volume control from each tuyere as described above and before that. Here, among the consecutive months from A to X, the result of performing the above-described air flow control from month N is shown, and in FIG. 14a, the output ratio is shown, and in FIG. The number of times of occurrence is shown in FIG. 3C, and the basic unit of mud is shown in FIG. As is apparent from these, the number of times of lap tapping gradually increases in the conventional control method in response to the high tapping ratio request from the K month to the W month. This occurs because hot metal accumulates in the furnace and discharges as a result of reducing the air volume from the tuyere and giving priority to hot metal discharge, regardless of the balance of the hot metal. On the other hand, from the N month when the control of the present embodiment is performed, by keeping the balance of ironing appropriately, accumulation of hot metal can be avoided and the number of times of lapping can be reduced.
[0035]
In addition, with the decrease in the number of lap outputs, the number of outputs is reduced by appropriately maintaining the output amount and output balance, and therefore the output time is reduced under a high output ratio. You can see that it has been extended. In addition, when the amount of brewing is not required or when a high amount of brewing is not required, the amount of air blown from the tuyere above the brewing hole is decreased relative to the amount of air blown from the other tuyere. As a result, the space between the coke filling layer and the mud deposit layer is reduced, thereby suppressing the wear of the mud deposit layer. As a result, the unit of mud can be reduced and the cost can be reduced. did it. Further, by stabilizing the operation in this way, it was possible to further extend the life of the furnace body.
[0036]
【The invention's effect】
As described above, according to the tapping control method of the present invention, the amount of air blown from the tuyere above the tapping hole is changed to that from other tuyere. Amount As a result, the space between the coke-filled layer and the mud deposit layer is reduced, which suppresses the wear of the mud deposit layer, so that the mud required to maintain the tap hole depth is reduced. The pressing amount may be reduced, and as a result, the mud intensity can be reduced.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a state from a tuyere of a blast furnace to a hearth part.
FIG. 2 is an explanatory view showing an example of a tap hole and tuyere.
FIG. 3 is an explanatory view showing another example of a tap hole and tuyere.
4 is an explanatory diagram of a flow control valve used in FIG. 2 or FIG. 3;
FIG. 5 is a characteristic explanatory diagram of the flow control valve of FIG. 4;
FIG. 6 is an explanatory diagram of a general output amount.
FIGS. 7A and 7B are explanatory diagrams before and after changing the tuyere air volume, in which FIG. 7A is a histogram showing the frequency rate of the slag index before the tuyere air volume is changed, and FIG. The histogram which shows the frequency rate of the slag index after having performed, (c) is an explanatory view of the output time for each output before and after changing the tuyere air volume.
FIG. 8 is an explanatory diagram showing changes in the slag index when the tuyere air volume is changed.
FIG. 9 is an explanatory view showing a change in heel balance when the tuyere air volume is changed.
FIG. 10 is an explanatory diagram showing changes in slag balance when the tuyere air volume is changed.
FIG. 11 is an explanatory diagram showing a change in the extraction time when the tuyere air volume is changed.
FIG. 12 is an explanatory diagram showing changes in the tap hole depth when the tuyere air volume is changed.
FIG. 13 is an explanatory diagram showing changes in the tap hole depth per unit mud pressing amount when the tuyere air volume is changed.
FIG. 14 is an explanatory diagram before and after changing the tuyere air volume, (a) is an explanatory diagram showing a change in the output ratio before and after changing the tuyere air volume, and (b) is an illustration of the tuyere air volume. An explanatory view showing a change in the number of laps before and after the change, (c) an explanatory view showing a change in the number of taps before and after changing the tuyere air flow, and (d) before and after changing the tuyere air flow It is explanatory drawing which shows the change of the mud basic unit.
[Explanation of symbols]
1 is the furnace wall
2 is the tuyere
3 is the raceway
4 is a coke packed bed
5 is a mud deposit
6 is space
7 is a tap hole
8 is a flow control valve
9 is hot metal

Claims (1)

In the blast furnace discharge control method for discharging the molten iron in the blast furnace together with the molten iron as a feed, the diameter of the tuyere above the tap hole is made larger than the tuyere diameter of the other tuyere, the tuyere having an increased blade diameter at least tapping hole upwards, interposed a flow control valve for adjusting the air volume of hot air, the air blowing amount from the upper tuyere out Zukuana, other blade The coke filling layer is brought closer to the mud deposition layer by reducing the air flow from the mouth relatively, the space between the coke filling layer and the mud deposition layer is reduced, and the lower end portion of the coke filling layer is the mud deposition layer. The mud deposit layer is covered with and protected by the coke filling layer, so that the wear of the mud deposit layer is suppressed and the amount of mud pushed in from the tap hole is reduced. Blast furnace output characterized by Control method.

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