JPS5833283B2 - Blast furnace operation method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a blast furnace operating method.

Therefore, the first object of the present invention is to quickly restore the cohesive zone which has lost its circumferential balance without having to take a break from the blast furnace.
Reduce the variation in Si), lower the blast furnace fuel ratio, etc.
The aim is to provide a method for operating a blast furnace.

The second purpose of the present invention is to drastically improve the circumferential imbalance of the cohesive zone without having to suspend the blast furnace, thereby reducing the fuel ratio in the blast furnace and the variation in pig iron (Si) over a long period of time. The aim is to provide a blast furnace operating method that can achieve these goals.

In the first place, the cohesive zone of a blast furnace consists of an ore cohesive layer (hereinafter referred to as the cohesive layer) and a coke layer, and the cohesive layer is found on the bedrock after dismantling the blast furnace, making it a difficult layer for debris to pass through. ing.

On the other hand, the coke layer has a certain porosity, so gas can pass through it very easily.

Therefore, it can be said that the cohesive layer in the cohesive zone plays the role of a gas rectifier.

In extreme terms, it can be said that the cohesive zone shape determines the gas reduction efficiency of the blast furnace and controls the blast furnace fuel ratio, which is a representative index of blast furnace operational performance.

Who are the parties involved in blast furnace operation? It is no exaggeration to say that various actions are taken in pursuit of an ideal cohesive zone shape with uniform circumference and balance.

However, as will be described later, there are various factors that disturb the circumferential balance of the cohesive zone during blast furnace operation, making it difficult to maintain a uniform circumferentially balanced cohesive zone over a long period of time.

Such a disruption of the circumferential balance of the cohesive zone not only directly means a decrease in gas reduction efficiency and an increase in the fuel ratio, but also induces fluctuations in the blast furnace furnace conditions, resulting in large variations in [:Si, l] in the pig iron. It becomes difficult to supply good hot metal.

However, until now there has been no method for fundamentally adjusting the shape of the cohesive zone, and the above-mentioned furnace conditions have typically been prolonged.

The cause of such a disturbance in the circumferential balance of the cohesive zone is when the charging amount in each direction is different due to a defect in the top charging device such as uneven wear of the large bell when charging the blast furnace raw material from the top of the furnace. In the case of ore receivers, if the internal profile inside the blast furnace becomes uneven due to damage to the bricks directly under the hardware or the formation of deposits*, and a mixed layer (layer of mixed coke and ore) is formed directly under the damaged area or deposits, Alternatively, there may be a temporary phenomenon of uneven loading due to fluctuations in furnace conditions (a phenomenon in which unloading differs depending on the direction), or the air volume from the tuyeres may be unbalanced.
As a result, the gas flows in a biased manner, causing a decrease in the in-furnace gas reduction rate ηCO1 and increasing the dispersion in the pig iron (Si).

In addition, due to the steady flow of gas due to an imbalance in the circumference, deposits are formed on the side of the gas drift, the heat load on the furnace body becomes abnormally high, and the charge material temporarily descends irregularly (hereinafter referred to as This is a major factor in the rise in the blast furnace fuel ratio.

Therefore, in order to increase the circumferential balance of the cohesive zone, we will: ■Restore the original functions of the equipment and furnace body (repair and adjust the furnace top charging device, etc., smooth the furnace profile by removing deposits, etc.) ■ Adjustment of charge distribution (change of munibubble armor notch, change of charging pattern, change of material charge level height, etc.) ■ Adjustment of gas flow in the lower part of the furnace Adjustment of tuyere diameter for each tube, for each tube The amount of heavy oil injection is being adjusted.

However, conventional methods have not been able to sufficiently correct the circumferential imbalance of the cohesive zone, and there has been a strong desire among those skilled in the art to propose an established technique.

For example, Japanese Patent Publication No. 42-26377 has been proposed as a method of reduced scale operation without air suspension.

However, the purpose of this is to lower the charge below the deposit line and remove the deposits using explosives such as dynamite without resting the air, and to adjust the cohesive zone in consideration of the circumferential balance. Not mentioned.

Therefore, at present, no established blast furnace operation method for cohesive zone adjustment has been proposed.

In addition, in view of the above-mentioned circumstances, the applicant has proposed an invention that can fundamentally improve the circumferential imbalance of the cohesive zone in Patent Application No. 54-213.
No. 36 (Japanese Unexamined Patent Publication No. 115904/1983).

The feature of this is that the circumferential balance of the cohesive zone is drastically improved by reducing the length of the wind.

However, in this invention, due to the reduction in wind shutdown, the coke ratio of the heat output from the increase in heat dissipated from the furnace body during wind shutdown increases, and the cavity above the charge during the reduction in wind shutdown has a large amount of CO and H2. Included in 2P
The top temperature was higher than normal and there was a risk of gas explosion at the top of the furnace, and due to the disturbance condition of reduced wind rest, after the wind started up,
There may be a drop in hot metal temperature, slippage, and blow-through.
There are interlayer points on the downwind where it is difficult to adjust the amount of heat.

The present invention has been made to solve the above-mentioned difficulties, and its features are as follows.

(1) Understand the blast furnace operation data over time under the blast furnace operation method, compare one or more of various data with the corresponding past trends as a standard, and identify abnormalities in the furnace and correct deviations. When it exceeds the set value, it is reduced, and then, during the above reduction, when the deviation in the circumferential direction falls within the set value, the charge level is restored to the level during normal operation and fused. A blast furnace operating method characterized by adjusting the belt.

(2) Operational data includes unloading of the charge, gas pressure, gas composition, and temperature at the same height level in iron (Si) or direction, and top gas temperature at the same radius level in each direction. A blast furnace operating method according to claim 1.

(3) Scale reduction is the amount of excess coke according to the scale reduction level.

The method of operating a blast furnace according to claim 1, which is carried out by adjusting the air volume and furnace top pressure according to the cohesive zone level.

(4) The reduction is performed between the upper end of the shaft and the middle stage of the shaft, or between the lower stage of the shaft and the morning glory.
Blast furnace operating method as described in section.

Here, we will explain why we have limited the various control elements of the blast furnace as factors for detecting abnormalities in the furnace when reducing the burden, and we have limited the various control elements of the blast furnace when returning the burden level to the normal operating level. The reason is shown below.

If the cohesive zone is uniform at the same height in each direction, the reduction and melting and dripping of the charge in each direction will proceed at the same time, and as a result, the unloading of the charge will be smooth and ηeo will be stable. , there is little variation in pig iron (Si).

In addition, since the gas amount and gas temperature at the same radius level in each direction are constant, the detection end information should show the same value for the furnace top gas concentration at the same radius level in each direction and the shaft pressure value at the same height level in each direction. be.

On the other hand, if the circumferential balance of the cohesive zone is disrupted, the unloading of the charge will be irregular, ηco will decrease, the variation in pig iron (Si) will increase, and the top gas concentration at the same radius level in different directions will differ. , the shaft pressure values at the same height level in different directions will show different values.

It is preferable to grasp the following management elements over time and use the corresponding past trends as a standard, and compare one or more of these data to detect abnormalities in the furnace. Implementing reduced scale operation is even more effective and is a necessary condition for stricter control of blast furnace operation.

That is, (a) variation in furnace mouth temperature at the same height level, O
) Variation in brick temperature at the same height level and furnace body temperature such as stave, (c) Gas temperature at the same radius level by direction, (e) Temperature distribution in furnace top thermography, (e) Furnace top charge profile, ( f) Variation in branch pipe airflow meters, (g) Core depth measurement results for each direction, (7) Deposition measurement results.

Furthermore, the reason for limiting the management factors when returning the charge is as follows.

We focused on the fact that the detection terminals that can accurately detect the circumferential balance of the cohesive zone even when the charge size is reduced are the two types of detection terminals proposed in the present invention and the temperature detection terminals such as furnace body temperature and sonde. did.

In other words, if the circumferential balance of the cohesive zone is improved while reducing the size of the charge, the variation in gas pressure at the same height level in different directions will decrease, and the gas composition at the same height level in different directions will decrease. Variations are reduced, and variations in temperature at the same height level in different directions are also reduced.

Further, the feature of the present invention is that the amount of excess coke is adjusted according to the scale reduction level, and the air volume and furnace top pressure are adjusted according to the cohesive zone level, and the reason for this will be described below.

Conventionally, the purpose of reduction during normal operation was to remove deposits caused by dynamite explosion, and in the process of lowering the charge level, the ventilation resistance of the charging uniformity was reduced, and gas was There was a constant risk of a blowout that could instantly reach the top of the furnace, a large slip, and the heat balance in the furnace would be disrupted, leading to a drastic drop in the temperature of the hot metal and cooling.

However, in the present invention, in order to detect abnormalities in the furnace at an early stage, since there are no disturbance conditions such as enlarged deposits, it is possible to maintain stable furnace conditions without blow-through or large slips, and to perform scale reduction to lower the charge level. As a result, the amount of heat output from the blast furnace can be significantly reduced, and the amount of excess coke due to the reduction in heat output can be significantly reduced.

The excess coke referred to here refers to the extra coke charged as a calorific value adjustment during the period of scale reduction operation, and the amount of excess coke refers to the amount of coke charged in excess of the amount during normal operation per scale reduction operation. It refers to

The method of determining the amount of excess coke during the downtime for removing deposits during normal operation is based on the slip at the time of scale reduction, the thermal compensation for blow-through, the slip due to deposits falling off when the air blows up and disturbs the gas flow. Heat compensation for blow-through, heat compensation necessary to melt fallen deposits, heat compensation for increase in heat dissipated from the furnace during downtime, and charge in the reduced space due to scale reduction. The heat compensation due to the decrease in retained heat was taken into consideration.

Therefore, in the conventional method of reducing airflow, there are too many disturbance conditions for each increase in heat output, and not only a large amount of excess coke is required, but the furnace conditions fluctuate more than expected, resulting in an increase in heat output. In this case, the hot metal temperature cools due to a significant drop, and conversely, if the heat output is less than expected, the hot metal temperature becomes excessively high.

In this way, it has been extremely difficult to adjust the amount of excess coke using the conventional method of reducing and resting air.

The present invention detects abnormalities in the furnace at an early stage without enlarging the deposits, and is capable of downsizing without changing the furnace conditions due to the downsizing operation without wind shutdown.

Therefore, there is slip during scale reduction, which is the excess amount of coke during the scale reduction air suspension for removing deposits, which is carried out during normal operation, thermal compensation for blow-through, slip due to deposits falling off when the air blows up, and disturbing the gas flow. Most of the heat compensation due to disturbance conditions is required, such as the heat compensation for blow-through, the heat compensation necessary to melt fallen deposits, and the heat compensation for the increment of heat dissipated from the furnace body during reduced air suspension. Therefore, it is only necessary to consider the heat compensation due to the reduction in heat retention in the charge due to the reduced space due to the size reduction, and the amount of excess coke is about 40% to 50% of the amount of excess coke mentioned above. was found to be sufficient.

In addition, since the operation is stable, by appropriately distributing the amount of excess coke according to the level of the charge to be reduced, it is possible to prevent a drop in hot metal temperature and an excessive rise in hot metal temperature, thereby stably supplying good hot metal. It will be possible.

For example, for reduced scale operation, an appropriate amount of excess coke may be charged depending on the raw material charge level and/or the furnace internal volume.

A preferred method of distributing the amount of excess coke is to charge about 90% of the excess coke when reducing the charge and about 10% during the course of raising the charge to a steady level.

Furthermore, it is preferable that 90% of the excess coke when reducing the charge be reduced to a certain proportion when reducing the length of the charge to the middle stage of the shaft, and when reducing the length of the charge to the lower stage of the shaft, approximately 60% of the excess coke is reduced to the middle stage of the shaft. Approximately 30% is distributed from the middle stage to the bottom of the shaft, and in the case of reduction to morning glory, 50% is distributed from the middle stage of the shaft to the bottom stage of the shaft, and 2 from the middle stage of the shaft to the bottom stage of the shaft.
0%, and 20% from the bottom of the shaft to the morning glory.

The reason why most of the excess coke is used during the reduction of the charge, and the charge level is drastically reduced in the process of returning to the normal operation level is due to the increase in heat output due to the reduction of the charge. It is better to concentrate the compensation in the first half, raise the hot metal temperature sufficiently, and use the residual heat to absorb the amount of excess coke that has decreased during the charge recovery process, without worrying about cooling, and to raise the hot metal temperature quickly. This is because it returns to normal levels.

Next, the reason why the present invention limits the adjustment of the air volume and furnace top pressure according to the cohesive zone level will be described below.

In the method of removing deposits using the above-mentioned scale reduction air break, the furnace conditions were unstable and the gas amount and gas temperature fluctuated, resulting in poor accuracy in estimating the cohesive zone. It becomes possible to accurately estimate the cohesive zone.

As a result, it was found that when the approaching speed between the top layer of the cohesive zone and the raw material charge becomes abnormally fast, a large slip occurs in which the charge falls abnormally rapidly.

This phenomenon is due to the fact that the bulk zone filling is the least between the charge level and the top layer of the cohesive zone, and as the distance between them becomes abnormally close, it becomes easy for gas to be selectively extracted from the top layer of the cohesive zone. This seems to lead to a slip.

In this way, the distance between the top layer of the cohesive zone and the charge level is determined by estimating the cohesive zone from the gas pressure, etc., which will be described later, to detect signs that the reduced width charge level and the top layer of the cohesive zone are abnormally close. What is necessary is to adjust the air volume and/or the furnace top pressure by taking the timing when the temperature approaches abnormally.

In addition, to understand the above symptoms, for example, rapid changes in ventilation,
This can also be done by rapidly changing the temperature at the top of the furnace.

Desirably, the furnace top pressure is increased in advance, the gas flow rate is suppressed, and the air volume is then reduced to Q, l Ni/1711F1 per internal volume.
Large slips can be prevented by reducing the degree of slippage.

It should be noted that if the timing of reducing the furnace top pressure is delayed, the air volume is reduced in advance, but it is also known that it is necessary to reduce the air volume by about 0.15 Ni/blood per internal volume.

By carrying out the present invention in this way, it is possible to reduce the coke under stable furnace conditions, thereby greatly reducing the amount of excess coke, and making it possible to adjust the amount of excess coke according to the level of reduction. By being able to accurately estimate the belt shape over time, it became possible to adjust the air volume and furnace top pressure to prevent large slips.

From the above, it was limited to adjusting the amount of excess coke according to the scale reduction level, and adjusting the air volume and furnace top pressure according to the cohesive zone level.

Furthermore, as a feature of the present invention, the reduction level at which the charge is lowered during normal operation is divided into a range from the upper end of the shaft to the middle stage of the shaft, and a range from the lower stage of the shaft to the morning glory for the reason described below.

By installing the two detection ends proposed in the present invention, it has become possible to control the circumferential balance of the cohesive zone with high accuracy from moment to moment.

Therefore, if the deviation of one or more of the shaft pressure value, gas composition, and temperature at the same height level in each direction during the reduction process falls within the set value, it is determined that the cohesive zone circumferential balance has been adjusted. Often there is no need to reduce the charge to the bottom of the shaft or even to the morning glory.

If you wish to fine-tune the circumferential balance of the cohesive zone for the above reasons, you should reduce the range from the upper end of the shaft to the middle of the shaft, and further improve the circumferential balance of the cohesive zone (reconstruction of the cohesive zone). If necessary, it will be necessary to reduce the length from the lower part of the shaft where most of the existing cohesive zone exists to the morning glory.

In addition, according to the present invention, we aim to improve the circumferential balance of the cohesive zone by reducing the length up to the middle of the shaft for a certain period of time, but if the improvement is not as desired, it is also possible to reduce the charge level in stages to the lower part of the shaft or to the morning glory. good.

Furthermore, the gas pressure gauge and gas sampling device proposed in the present invention can be used effectively for the following purposes.

Using gas pressure gauges that are installed centrally from the shaft to the morning glory and in different directions, the charge level during scale reduction can be accurately detected, and in case of problems such as wire breakage of the deep measuring device during scale reduction. It will be a powerful backup.

The principle by which the gas pressure gauge detects the charge level is that when the charge level passes through the gas pressure gauge, the pressure value of the gas pressure gauge matches the furnace top pressure.

Therefore, by utilizing this principle and arranging gas pressure gauges in series, the detection accuracy can be further improved.

Gas analyzers installed in different directions from the shaft to the morning glory can also be used to detect blast furnace gas that tends to accumulate in the lower part of the shaft during wind down periods.

By detecting gas in each direction from the shaft in this way, it is possible to prevent the risk of a top gas explosion that may occur during reduced air suspension.

Note that the pressure at the top of the furnace after a reduction in air is approximately equal to atmospheric pressure, so gas is detected by sucking gas with a pump and gas analysis is performed during the reduction in air.

As described above, the present invention can easily, safely, and inexpensively balance the circumference of the cohesive zone compared to the method of reconstructing the cohesive zone, which drastically improves the cohesive zone by reducing the air length. It can be said that this is an innovative method that allows fine adjustments to be made depending on the level of reduction of the material.

Next, the present invention will be explained in more detail with reference to an example of operation shown in the drawings.

Figures 2 and 3 show the number of slips (an indicator of poor unloading), ηco (an indicator of gas reduction efficiency), and the R of pig iron (Si), which are management factors for abnormalities in the furnace. degree, from the maximum [Si] to the minimum (S
i) was subtracted to show the monthly average of that value.

Comparing Figures 2 and 3, it is clear that in Figure 3, the number of slips has increased since May, the decrease in ηeo has been severe, the variation in pig iron [Si] has also increased, and the cohesive zone has increased. This shows that the circumferential balance has become significantly disturbed, and we think it is time to reduce the area from the bottom of the shaft to the morning glory in order to fundamentally improve the cohesive zone.

Further, the operational state shown in FIG. 2 has not yet reached the state shown in FIG. 3, and can be sufficiently dealt with by reducing the length from the upper end of the shaft to the middle stage of the shaft.

A preferred embodiment of the above management factors is that the number of slips is 2.0 to 3.0 times per 2 consecutive months from the average of the most recent 2 months.
When the number of days increases, ηeo is 2 consecutive days higher than the average of the last two months.
When the power decreases by 0.3% to 0.5% per month, the R of pig iron (Si) decreases by 0.03 to 0.0 for two consecutive months from the last two months.
5% increase, when one or more of the above occurs, the scale is reduced between the upper end of the shaft and the middle of the shaft to finely adjust the circumferential balance of the cohesive zone. 3. Slip is higher than the average for the most recent two consecutive months.3.
When ηeO increases more than once, when ηeO increases by 0.6% or more for two consecutive months from the average of the most recent two months, when R of pig iron (Si) increases for two consecutive months from the average of the most recent two months. When the increase is 0.06% or more, if the top gas concentration at the same radius level in each direction differs greatly as shown in Figure 4, the shaft pressure value at the same height level in each direction as shown in Figure 5. When one or more of the following cases occur, the method is to reduce the length between the lower part of the shaft and the morning glory, thereby drastically improving the circumferential balance of the cohesive zone.

Even more preferably, the following management elements are grasped over time,
If one or more of these data are compared with the corresponding past trends to detect abnormalities in the reactor, even if the above management standards are not met, it is possible to detect disturbances in the cohesive zone circumferential balance. It is even more effective to take this as a symptom and reduce the length between the upper end of the shaft and the middle of the shaft.

(b) Variations in furnace mouth temperature at the same height level, (b) Variations in brick temperature and furnace body temperature such as staves at the same height level, (c) Gas temperature at the same radius level by direction, and (d) Furnace top. Temperature distribution of thermography, (e) distribution of furnace top profile meter, (f) variation of branch pipe airflow meter,
(G) Shaft micro-pressure by direction, (7) Tuyere micro-pressure by direction, (
(1) Core depth measurement results by direction, (3) Thickness of deposits.

Next, the amount of excess coke is determined according to the level of reduction of the charge.

This amount of excess coke is approximately 40 to 50% compared to the conventional method of reducing airflow using dynamite explosion for the purpose of removing deposits.
is sufficient.

In other words, there is almost no need to consider the heat output due to the influence of deposits, and it is only necessary to consider the heat compensation valve due to the reduction in heat retained in the charge due to the reduced size space.

Here, the amount of excess coke according to the present invention when the A blast furnace with an internal volume of 1730 m' is reduced in size to a morning glory of 18 m is estimated below.

(Assumptions) ■ Charge specific heat Cp (coke) = 0.31X103k
cal/l-℃ ■ Charge specific heat Cp (Ore) = 0.22X10”kc
al/l-'C ■ Or e/e oke = 3.40 ■ Coke base = 11t/ch- ■ Number of charges that should enter the reduction space = 30 charges ■ Average temperature of the charge up to 18m reduction = 600℃ (1)
Specific heat per charge 11X0.31X10 +11X3.40X0.22
Xi 03 = 11.64X103 (kcal/'C charge) (2) Charge heat retention for reduced space 11.64X10 X600X30 = 209.5X1
0 kcal (3) Find the amount of coke for compensating the amount of heat.

From C+3AO2=CO+2450 kcal/9, the calorific value per 1 ton of Coke is 2205×103 kcal/l when the coke ash content is 10%.

209.5 x 106/2205 Although an excess amount of coke was used, an excess coke amount of 95 tons is sufficient for the reduced scale operation according to the present invention.

Note that the amount of excess coke naturally varies depending on the erosion condition of the furnace bricks and the difference in the internal volume of the blast furnace.

After determining the charge level to be reduced and determining the corresponding amount of excess coke, appropriate excess coke is removed according to the charge level without worrying about cooling due to a drop in hot metal temperature and without raising the hot metal temperature excessively. It is necessary to distribute the amount.

FIGS. 6 and 7 show an embodiment in which excess coke is distributed in accordance with the reduction level.

Figure 6 shows the charge level at SL below 10 to the middle of the shaft.
In this example, 90% of the excess coke amount is charged when the charge is reduced in size, and the remaining 10% is charged during the process of returning the charge level, and each charge is It is distributed in fixed proportions depending on the level.

Figure 7 shows an example in which the charge level is reduced to 18m below the SL to Morning Glory.When reducing the charge level, 90% of the excess coke amount is charged, and the remaining 10% is In the process of restoring the charge level, it is distributed at a fixed ratio according to the charge level.

The method of distributing 90% of the excess coke when reducing the charge is to distribute 50% to the middle of the shaft, 20% from the middle of the shaft to the lower shaft, and 20% from the lower shaft to the morning glory. This prevents cooling and excessively high hot metal temperature.

Next, the air volume and furnace top pressure during reduced scale operation will be explained based on the embodiment shown in FIGS. 6 and 7.

Since the scale reduction operation according to the present invention can maintain stable reactor conditions, the shape of the cohesive zone can be accurately estimated moment by moment based on the detection end input into the computer.

As shown in Figures 6 and 7, in response to signs that the distance between the charge level and the top layer of the cohesive zone is approaching abnormally quickly, the furnace top pressure is increased in advance, and the gas flow rate in the furnace is increased. After that, the air volume per internal volume is reduced to 0. I Nrrt/
171E11 to prevent fluctuations in furnace conditions such as slips.

Such fine-grained adjustments enable reduced-scale operation under stable reactor conditions.

With the charge lowered to the desired reduction level under stable conditions, the circumferential balance of each is measured moment by moment by using the two types of detection terminals proposed in this invention and temperature detection terminals such as furnace body temperature and sonde. In addition to confirming this, the amount of Zn in the gas ash and the amount of alkali in the slag will also be analyzed over time.

As shown in Fig. 8, when the variation in gas pressure at the same height level is reduced, when the variation in gas composition at the same height level is reduced, when the variation in stave temperature at the same height level is reduced, When the amount of Zn in blast furnace ash started to decrease,
It was confirmed that the circumferential balance of the cohesive zone had improved, or that the amount of deposits falling off had decreased, taking into consideration the timing when one or more of the alkali levels in the slag started to decrease. Confirm that this is the case and restore the charge level to the normal operating level.

In addition, in order to carry out the scale reduction operation according to the present invention, it is proposed to install shaded pressure gauges and gas collection devices from the shaft to the morning glory in each direction as shown in FIG.

That is, gas sensors and/or pressure sensors are installed at at least two pressure points in the circumferential direction of the blast furnace, and multiple stages are installed between the shaft and the morning glory, and the number of installed stages increases toward the bottom of the furnace. This is what I did.

The reason for this is that it is necessary to accurately detect the uniformity of the circumferential balance of the cohesive zone by lowering the raw material charge level during reduced scale operation.

This is because, by reducing the size, a cavity is formed above the charge level, exposing a portion of the detection end and reducing its function by half.

The gas pressure gauge outlet may have the same structure as the pressure gauge outlet conventionally installed in blast furnaces.As shown in Fig. 10, a flange 2 is welded to an ordinary steel pipe 1, and the flange 2 is welded with a port 3. It is fixed to the skin, gas is introduced from the steel pipe 1, and the pressure is measured.

The measured pressure side in each direction is input to a computer 4 that compares and calculates the variation in circumference for each step, and is printed out at regular intervals.

Further, the outlet of the gas collection device may have the same structure as the outlet of the gas pressure gauge, as shown in FIG.

Gas is introduced through a steel pipe 5 and analyzed by a gas chromatography analyzer 6 in each direction.

The measured gas analysis for each direction is input to a computer 6 that compares and calculates the circumferential variation for each step, and is printed out at regular intervals.

Next, examples of the present invention will be described.

Example 1 Example of fine adjustment of cohesive zone circumferential balance.

Slip in A blast furnace with a furnace volume of 1730 m'', ηe
As a result of comparing the trends in pig iron (Si) R″ with the average of the last two months, the slip increased once in two consecutive months, and ηe
o decreased by 0.2% for two consecutive months, and beans in pig iron (Si) increased by 0.04% and 0.05% consecutively.

Since the R of the pig iron (Si) had increased above the control standard, it was determined that fine adjustment of the circumferential balance of the cohesive zone was necessary, and the charge level was reduced to 6 m below the SL, which is the upper stage of the shaft. It was decided to charge about 30 coke to reduce the amount of heat retained by the charge due to the reduced size of the cavity.

As per the standard, excess coke was distributed at 90% during the scale reduction process and 10% at the time of return to scale reduction, and the 90% distribution amount during the scale reduction process was set at a fixed ratio depending on the charge level.

In addition, the air volume before size reduction is constant at 1.25 Nm''/mj!l per internal volume as before size reduction, since the cohesive zone top layer level does not approach rapidly even when the charge level is reduced. The furnace top pressure was also kept constant.

When the scale reduction reached 6 m, it was maintained at the same scale reduction level for about 5 hours, and as a result, the variation of the gas pressure gauge at the same height level (maximum gas pressure car minimum gas pressure at the same height level) was 150 t/min at the bottom of the shaft. Since cWL decreased from 120ft/cd to 60t/cIIL at 7or/ct furnace belly, it was judged that the circumferential balance of the cohesive zone had been improved, and the charge level was returned to the original normal operating level.

As a result, the slip was resolved, and ηeo for the next month improved by 0.4% compared to the previous month, while beans in pig iron (Si) decreased by 0.05%.

Incidentally, the scale reduction operation proceeded extremely smoothly with no slip, and the hot metal temperature was slightly high at 1510°C only at 2 taps, but returned to the normal level of 1490 to 1500°C per day at Btap IJ.

Example 2 Example of drastic adjustment of cohesive zone circumferential balance.

Slip in A blast furnace with a furnace capacity of 1730 m''.

As a result of comparing the trends in ηeo and pig iron (Si) R with the average of the last two months, slip increased three times in two consecutive months, and η
co continuously decreased by 0.5% and 0.6% for two months, and R of pig iron (Si) increased by 0.06% for two months.

Furthermore, the ηeo of the furnace top gas at the same radius level in each direction differs by 1.5% on the furnace wall side, and the dispersion in the east-west direction at the same height level at the top of the shaft also differs by 1501/cr/L, so the cohesive zone It was determined that the circumferential balance of the reactor had been significantly disrupted, and the charge level was reduced by 16 m below the SL to the reactor belly.

The amount of excess coke was decided to be approximately 85% as a reduction in the amount of heat retained by the charge due to the reduced size space.

As for the distribution of excess coke, 90% was charged in the reduction process as per the standard, and the remaining 10% was distributed in a fixed proportion according to the charging level in the process of restoring the charging level.

The method of distributing 90% of the excess coke amount when reducing the charge was 60% to the middle of the shaft, 20% from the middle of the shaft to the lower shaft, and 20% from the lower shaft to the morning glory.

In addition, the air volume before reduction is 1.20 N7F+”/inner volume.
run, the furnace was operated at a top pressure of 0.80 kg/cI/l, but there were signs that the distance between the charge level and the top layer of the cohesive zone was approaching abnormally quickly at a reduction of 13 m. Therefore, the furnace top pressure was immediately increased to 90 kg/crl, and 3 minutes later, the air volume per internal volume was decreased by 0.05 Nm"/arm, and 2 minutes after that, the air volume was further decreased by 0.05 Nm"/1 m. Ta.

As a result of holding for about 1 hour at a reduced scale of 16 m, it was confirmed that the variation in the same height level of morning glories in different directions was reduced by about 1.5%, and the charge level was returned to the original normal operation level. .

As a result, although there were some small slips, the minimum level of hot metal temperature before and after scale reduction was 1480℃, and the maximum temperature was 152℃.
0'C3tap continued, but then normal level of 1490
It returned to ~1500'C.

As a result, the slip was almost eliminated, and the following month's η
co improved by 0.6% compared to the previous month;
beans decreased by 0.06% and the fuel ratio decreased by 41 #/l-p.

Incidentally, the A blast furnace is a blast furnace in which shaft pressure gauges and shaft gas pressure gauges are arranged in three stages in each of four directions at each location: the middle stage of the shaft, the lower stage of the shaft, the furnace belly, and the morning glory level.

Example 3 Example of fine adjustment of cohesive zone circumference balance.

Slip in a B blast furnace with a furnace capacity of 1150 m''.

Comparing the trends in ηeo and pig iron (Si)R with the averages for the most recent two months, it was found that ηeo and pig iron (Si)R remained almost unchanged, but the slip rate continued to increase by 0.5 times/day in two consecutive months. As the temperature at the furnace mouth increased and the variation in furnace mouth temperature also tended to rise, it was determined that although it was below the standard for fine adjustment of the cohesive zone, the circumferential balance was slightly disrupted, and the SL was adjusted to 5000% below the shaft to the top end.
I decided to reduce the size to .

Approximately 20 tons of excess coke was charged as a reduction in the heat capacity of the charged material due to the reduced size cavity, and the distribution of the excess coke was made in exactly the same manner as the above-mentioned criteria.

In the process of reduction, the cohesive zone top layer level and the raw material charge distance are 10
Since the furnace approached from m to 8 m at a nearly constant speed, the air volume per internal volume and furnace top pressure were 0 and 13 Nm/cr, respectively. t
, was kept constant at 0.85 kg/at/i.

After reducing the length to 5000mm below the SL and holding it as it is for about 6 hours, the temperature of the lower shaft bricks was determined by direction (
The maximum temperature - minimum temperature) decreased from 220℃ to 115℃, and the variation in temperature of morning glory bricks by direction was also 150℃.
It was determined that the circumferential balance of the cohesive zone had been improved, and the charge level was returned to the original normal operating level.

During the scale reduction operation, the operation progressed smoothly without slipping, and the hot metal temperature was 1.
The temperature remained stable at 480 to 1510°C, with almost no slippage.

As described above, by adopting the present invention, the following effects can be achieved.

1 Fine adjustment of the cohesive zone circumferential balance.

In the case of reduction to the top or middle of the shaft,
As the loading of the raw material for the charge decreases, the lump zone (the part of coke and ore above the cohesive zone) decreases, the upper gas diffusion in the lump zone decreases, and the blast furnace gas becomes central flow oriented. Become.

Therefore, if the top layer level is biased in a certain direction, fine adjustment can be made to the center of the top layer (FIG. 1A).

2. Drastic adjustment of the circumferential balance of the cohesive zone.

In the case of reduction to the lower part of the shaft or to the morning glory, by reducing the length below the level of the existing cohesive zone, a uniform cohesive zone, which is completely different from the existing cohesive zone with an unbalanced circumference, is rebuilt.

Therefore, the conventional gas drift is eliminated and ηCO is significantly improved (Fig. 1).

3. Stabilization of reduced scale operations.

By detecting abnormalities in the furnace early and performing reduced-scale operation to lower the charge level without taking a wind break, and adjusting the air volume and furnace top pressure according to the cohesive zone level, blow-by and slipping may occur. Reduced scale operation can be performed under stable reactor conditions.

4 Significant reduction in excess coke amount.

As mentioned above, by being able to perform reduced scale operation under stable reactor conditions,
The amount of excess coke is approximately 40-50% compared to the conventional reduced-scale wind rest.
This results in a significant cost reduction.

5 Prevents cooling and excessively high hot metal temperature.

There is no need to worry about cooling, and there is no need to worry about excessively high hot metal temperature because it can be reduced under stable furnace conditions, it is a reduced-scale operation without wind breaks, and the amount of excess coke is distributed according to the charge level. It can be prevented.

6 Accurate detection of cohesive zone circumferential balance under reduced scale,
Detects the level of reduced charge and prevents top gas explosion during downtime.

By providing the pressure gauge and gas sampling device centrally installed from the shaft to the morning glory according to the present invention, it has become possible to accurately detect and manage the circumferential balance of the cohesive zone under reduced scale.

In addition, by centrally installing gas pressure gauges from the shaft to the morning glory, it is possible to detect the reduced charge level in each direction with high accuracy. Since it is installed, it can also be used to detect blast furnace gas that tends to stay in the lower part of the shaft after a reduction in wind shutdown, and the risk of a top gas explosion during a reduction in wind shutdown can be prevented.

7. Removal of deposits.

In the process of reducing the size of the charge material or in the process of returning to the normal level, it is expected that the deposits will come off due to the effect of colliding the charge material with the deposits.

Therefore, the working profile inside the furnace becomes smooth during unloading after the wind down is reduced, and the unloading of the charge goes smoothly.

8 Zn, alkali discharge from blast furnace, formation of deposits,
Suppression of growth and stabilization of furnace conditions.

According to the disassembly results of each blast furnace, the in-furnace concentration temperature of Zn and alkali is 400-1100℃ for the former and 800-130℃ for the latter.
It is 00°C.

The temperature from the upper shaft to the middle shaft is 200-8.
00℃, temperature from the bottom of the shaft to the morning glory is 900-1
Since the temperature is 500°C, depending on the scale reduction level, Zn,
A portion of the alkali evaporates and is discharged from the furnace together with blast furnace gas ash.

The main components of the deposits that have fallen off are Zn and alkali oxides, which are also exposed to high temperatures and can be discharged from the blast furnace through blast furnace gas ash or slag, thereby suppressing the formation and growth of deposits.

It is also known that as the amount of alkali circulating increases, the coke present in the lower part of the blast furnace cracks and becomes finer. However, with the present invention, some of the alkali is discharged from the furnace, reducing the amount of alkali circulating. This reduces coke fineness, improves ventilation, and stabilizes furnace conditions.

9. Reduced variation in pig iron (Si).

Since the circumferential balance of the cohesive zone is uniform, the melting of the cohesive layer in each direction is reduced and the level is uniform, the hot metal components are stable, and good hot metal can be supplied.

Furthermore, since the dispersion of the pig iron (Si) can be reduced, it is possible to lower the pig iron (Si).

10 Reduction of furnace heat load.

By being able to prevent gas drift due to an imbalance in the circumference of the cohesive zone, the heat load on the furnace body is reduced, and the heat dissipated from the furnace body is also reduced.

As a result, it becomes possible to maintain the original furnace function for a long period of time, and the heat output of the blast furnace is reduced due to the heat dissipation of the furnace body.

11 Increase in ηeo, decrease in fuel ratio.

The above-mentioned effects 1 to 10 can be combined to greatly reduce the fuel ratio, and at the same time, increase ηeo, making it possible to maintain highly efficient operation over a long period of time.

[Brief explanation of drawings]

Figure 1A2 shows a conceptual diagram of cohesive zone fine adjustment and cohesive zone reconstruction, Figures 2 to 11 show an embodiment of the present invention, and Figure 2 shows the cohesive zone fine adjustment. The number of slips, ηco, which indicates an abnormality in the furnace during adjustment. (Figures showing examples of Si and IR, Figures 3 to 5 are the number of slips representing abnormalities in the furnace when reconstructing the cohesive zone, ηco
, (Si)R, furnace top gas concentration, and a diagram showing an example of shaft pressure distribution according to direction. Figure 6 is a diagram showing a method of adjusting air volume, furnace top pressure, and excess coke amount when finely adjusting the cohesive zone. , Figure 7 is a diagram showing how to adjust the air volume, furnace top pressure, and excess coke amount when reconstructing the cohesive zone. Figure 9 is a diagram showing the flow of gas pressure gauges and gas sampling equipment installed in different directions, Figure 1.
0 is a diagram showing the outlet of the gas pressure gauge and the gas pressure comparison calculator, and FIG. 11 is a diagram showing the outlet of the gas component sampling device and the gas component comparison calculator.

Claims (1)

[Claims] 1. Blast furnace operation data in the blast furnace operation method is grasped over time, and one or more of various data are compared based on the corresponding past trends to detect abnormalities in the furnace. When the deviation exceeds the set value, the charge level is reduced, and then the charge level is restored to the level during normal operation by determining the timing when the deviation in the circumferential direction falls within the set value during the above reduction. A blast furnace operating method characterized by adjusting the cohesive zone by adjusting the cohesive zone. 2 Operational data includes unloading of charge, ηco, iron medium (
Si) or gas pressure at the same height level in each direction. The blast furnace operating method according to claim 1, wherein the top gas concentration is at the same radial level for each gas component, temperature, and direction. 3 Scale reduction is the amount of excess coke according to the scale reduction level. The method of operating a blast furnace according to claim 1, which is carried out by adjusting the air volume and furnace top pressure according to the cohesive zone level. 4. The blast furnace operating method according to claim 1, wherein the reduction is performed between the upper end of the shaft and the middle stage of the shaft, or between the lower stage of the shaft and the morning glory.