JP3514120B2 - Distribution control method of blast furnace top charge - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast furnace operation in which ores and coke are charged in layers, by appropriately controlling the gas flow distribution in the blast furnace by controlling the distribution of the charge from the top of the furnace. The present invention relates to a method for controlling the distribution of the blast furnace top charge for stabilizing the temperature.

[0002]

2. Description of the Related Art In a blast furnace operation, iron raw materials such as iron ore and sintered ore (hereinafter referred to as "ores") and coke are alternately charged in layers from the furnace top. Controlling the distribution of this charge to optimize the abundance ratio of ore and coke and the gas flow distribution in the radial direction of the furnace, the gas rising in the furnace and the coke and ore descending in the furnace It is essential for efficient heat exchange and reaction, and for stable and efficient operation of the blast furnace.

When charging raw materials (ores and cokes) from the top of the furnace, generally, a charging device such as a movable armor or a swirling chute is used to make the raw materials uniform in the circumferential direction. The surface of the raw material deposited in the furnace has a downward slope toward the central part of the furnace in order to drop it into a predetermined area near the inner peripheral part.

The angle of this inclination (hereinafter referred to as "deposition angle") changes depending on the change of the falling point of the raw material, the fluctuation of the raw material particle size, and the like. In particular, the layer of coke charged immediately before the charging of the ore collapses due to the drop impact during the charging of the ore, and further, the flow along the inclined surface occurs, so the middle of the furnace The profile shape (coke deposition shape) of the surface of the coke layer varies in the part (the middle part between the center part and the peripheral part in the furnace). Therefore, the deposition angle formed by the surface of the coke layer (hereinafter, simply referred to as “coke deposition angle”) is lower than the deposition angle immediately after the coke is charged. Moreover, it is impossible to detect the newly formed deposition angle, and the collapse and inflow phenomenon itself is unstable, so the collapse and inflow phenomenon of the coke layer surface control the distribution of the charge. It is said to be a factor that reduces the accuracy of sex.

On the other hand, in the vicinity of the center of the furnace, the gas flow velocity sometimes increases as the coke fluidizes, so that the coke deposition angle fluctuates greatly and the gas flow distribution near the center becomes unstable. Become. In the vicinity of the furnace wall, raw materials,
In particular, the turbulence of the surface of the raw material (particularly the ore) due to the impact when the ore falls causes a destabilization of the gas flow in the peripheral part of the furnace.

Further, in recent years, the blast furnace operation has shifted to a high PCI operation in which a large amount of pulverized coal is blown from the tuyere along with the hot air in order to reduce the coke ratio, and the amount of ore charged from the furnace top corresponds to the amount of coke. It is increasing in comparison. Therefore, the change of the profile shape of the surface of the coke layer near the dropping point of the charged ore and the middle part of the furnace and the increase of the fluctuation range of the deposition angle near the center of the furnace tend to be promoted. There is an increasing demand for improved accuracy of distribution control.

As a method for controlling the distribution of the blast furnace charge, Japanese Patent No. 2608504 discloses a drop trajectory of the charge in consideration of the influence of the top gas velocity on the fall trajectory of the charge. There is disclosed a method in which the dropping position of the charging material is obtained from the above to estimate the surface shape of the deposit in the furnace, and the distribution of the charging material is controlled based on the difference from the target surface shape of the deposit.

In Japanese Patent Publication No. 6-63009,
The distribution status of the gas flow and the charge is deduced from the proper range by inferring the distribution status of the gas flow and the charge by the knowledge engineering system equipped with the knowledge base for judging the distribution status of the gas flow and the charge in the blast furnace radial direction In this case, a method for controlling the distribution of the charging material based on the optimum charging material distribution control condition for performing the charging material distribution prediction model calculation to return to the proper region is disclosed.

However, in the charging distribution control method described in Japanese Patent No. 2608504, collapse and inflow of the coke layer in the middle portion of the furnace described above, fluctuation of the deposition angle near the center of the furnace (deposition) Change of surface shape after),
Unstable and undetectable phenomena such as disturbance on the surface of the raw material deposit layer (change in profile shape of the raw material deposit layer) near the ore drop point cannot be taken into consideration, and the target charge distribution is It is impossible to do. In addition, Japanese Patent Fair 6-6
Since the charging distribution control method described in Japanese Patent No. 3009 is based on knowledge engineering constructed by past results, when the above phenomenon still occurs, the gas flow and charging distribution in the radial direction in the reactor The accuracy of prediction for fluctuations in V is decreased, and it is difficult to obtain the target gas flow distribution by obtaining the optimum charge distribution control conditions.

[0010]

SUMMARY OF THE INVENTION The present invention solves the above problems in the prior art, improves the accuracy of the distribution controllability of the charge from the top of the furnace, and appropriately controls the gas flow distribution in the blast furnace. It is therefore an object of the present invention to provide a method for controlling the distribution of blast furnace top charge, which enables stable blast furnace operation even under high PCI operation.

[0011]

The gist of the present invention resides in the following method (1) and (2) for controlling the distribution of blast furnace top charge.

(1) In a blast furnace operation in which ores and coke are charged in layers, the radial direction of the furnace top is determined from the raw material charging conditions, the blowing conditions, and the profile shape measurement values of the raw material deposition layer surface.
Oriented Raw Material Surface Shape, Ore / Coke Ratio and Particle Size Distribution
When calculating the structure and gas flow distribution of the raw material deposit layer consisting of, the gas composition distribution in the furnace radial direction calculated based on the structure and the gas flow distribution of the raw material deposit layer at the top of the furnace and measured in the upper part of the furnace The gas flow obtained by correcting and calculating the deposition angle of the coke charged immediately before the charging of the ore in the middle part of the furnace so that the difference with the gas composition distribution in the furnace radial direction is minimized. Based on the difference between the distribution and the preset target gas flow distribution , the movable armor knock
C, large bell stroke, number of turns of turning chute and
By adjusting at least one or more of the
A method for controlling the distribution of the blast furnace top charge, which comprises controlling the distribution of the furnace interior charge.

(2) The correction of the deposition angle for calculating the structure and the gas flow distribution of the raw material deposition layer at the top of the furnace was further performed for the coke deposition angle at the center of the furnace, and then at the periphery of the furnace. The method for controlling the distribution of the blast furnace top charge according to (1) above, which is performed for the deposition angle of ore.

The above-mentioned "central part in the furnace" means the innermost area including the center of the furnace when the cross section of the blast furnace is divided into three areas by a concentric circle having the same center as the center of the blast furnace,
The “furnace inner peripheral part” means the outermost region including the vicinity of the furnace wall part, and the “furnace middle part” means the middle region between the “furnace central part” and the “furnace inner peripheral part”. .

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The following (1) and (2) are described below.
The distribution control method of the blast furnace top charge according to the invention will be described in detail. The method for controlling the distribution of the blast furnace top charge of the present invention (the method of the present invention) refers to both of these methods.

FIG. 1 is a simulator for predicting the distribution of charges used in the method of the present invention (hereinafter, "a model for predicting charges distribution",
Or, it is a diagram for explaining the function of "model"), which is a case where the method of the present invention is applied to a bell-type blast furnace.

In FIG. 1, the raw material 2 charged into the furnace through the large bell 1 collides with the movable armor 3 during the fall and the falling direction is corrected, and a predetermined area near the periphery of the furnace ( It falls in the range of the raw material falling width 6 shown in the drawing) and is deposited in layers. Reference numeral 4 is an iron raw material (ore), and reference numeral 5 is a coke that has fallen and accumulated immediately before. Coke 5
The layer of has a profile shown by a broken line immediately after being charged, but the falling impact of the iron raw material (ore) 4 charged after that causes collapse of the coke layer 7 and inflow in the middle part of the furnace. , Changes to the profile shown by the solid line in the figure. Reference numeral 8 shows the fluctuation of the deposition angle on the surface of the coke layer near the center of the furnace.

This charge distribution distribution prediction model is used to calculate the raw material layer (deposition) in the radial direction of the blast furnace from the raw material charging condition, the blowing condition, the deposition angle of the raw material layer obtained by a sensor (profile meter), and the top gas composition distribution. It is a simulator for estimating the structure of the bed) and the gas flow distribution, and consists of the following parts. That is, the raw material falling trajectory calculation, the surface profile shape calculation after the raw material falling, the particle size segregation calculation in the radial direction, and the gas flow distribution calculation based on the structure of the raw material layer (deposited layer).

As an operation for controlling the charge distribution,
When controlling the falling point of the raw material, the operation to change the extrusion amount of the movable armor is changed in the blast furnace equipped with the bell-type charging device, and the tilt angle of the swirling chute is changed in the blast furnace equipped with the bellless charging device. Do the operation. When controlling the charging rate of raw materials, the operation of changing the stroke of the large bell is performed in the bell type blast furnace, and the operation of changing the flow rate adjusting valve is performed in the bellless type blast furnace.

In the above-mentioned raw material drop trajectory calculation, the initial velocity of the raw material from the charging device is calculated, and then the drop trajectory is calculated to obtain the raw material drop point. When the operation is performed by the movable armor, the raw material falling point and the raw material falling width in the vicinity thereof are calculated in consideration of the repulsion by the armor plate, and this is reflected in the surface profile shape calculation after the raw material is dropped as described below. In addition, the validity of the drop trajectory and the calculated value of the drop point of the raw material was verified by the raw material drop experiment result.

In the above-mentioned calculation of the profile shape of the surface after the raw material is dropped, after the raw material is dropped, the surface shape is calculated based on the surface profile measurement value (deposition angle of the raw material layer) of the raw material deposited layer in the radial direction of each raw material obtained by the profile meter. To decide. At that time, the falling impact of the ore causes collapse at the upper part of the coke slope and inflow to the lower part of the slope. The deposition angle obtained by measuring the profile shape of the surface of the raw material deposition layer is adjusted using the reduction width to determine the overall surface shape.

In the above-described radial grain size segregation calculation, the grain size segregation when each raw material having a different grain size distribution is deposited on the slope is calculated, and the layer structure in the radial direction of each deposited raw material is calculated.
That is, the distribution state of the ore / coke ratio (hereinafter referred to as “O / C”), the particle size and the porosity is calculated.

Further, in the gas flow distribution calculation based on the above-mentioned raw material layer (deposited layer) structure, the rising gas amount given by the blowing condition is distributed according to the layer structure distribution obtained in the above, and the gas flow distribution is obtained. To calculate.

Further, by assuming the direct reduction rate in the furnace, the O / C in the radial direction in the furnace obtained above is obtained.
The gas composition distribution in the radial direction in the furnace can be calculated based on the gas flow distribution obtained by

The difference between the gas composition distribution in the in-furnace radial direction calculated in this way and the actual gas composition distribution obtained by analyzing the gas sampled by the gas sampler installed in the radial direction of the furnace top is , Coke layer collapse and inflow in the middle part of the furnace that cannot be detected from the profile shape measurement value of the raw material deposit layer surface obtained from the furnace top, and profile profile change of the raw material deposit layer surface in the central and peripheral parts Means degree.

Therefore, while correcting the deposition angle of the coke in the middle part of the furnace due to the collapse or flow of the coke layer charged immediately before the charging of the ore, the coke in the center part of the furnace is further corrected. While correcting the deposition angle of the ore and the deposition angle of the ore in the furnace periphery, that is, by giving different values to the deposition angle in the middle, center and peripheral regions of the furnace If the difference between the measured gas composition distribution and the measured gas composition distribution is minimized, the layer structure represented by the deposition angle in each region in the furnace at that time is It can be said that the layer structure is represented with high accuracy. The above-mentioned "minimum difference between the calculated value of the gas composition distribution and the measured value" is most preferably the same, but it is not always the same, and the operator judges that the difference is the minimum depending on the situation at that time. If it is in a state of

FIG. 2 is a flow chart showing the calculation procedure of the charge distribution prediction model used in the above calculation. When carrying out the method of the invention of (1) above, the calculation is performed excluding the portion surrounded by the dashed line in the figure, and when carrying out the method of the invention of (2), the portion surrounded by the dashed line is included. Calculate. In the following description, the method surrounded by the one-dot chain line, that is, the method of the invention of (2) above will be described, and then the method of the invention of (1) will be referred to.

In FIG. 2, blowing conditions, raw material charging conditions,
The top exhaust gas composition obtained based on the above calculation of
And the deposition angle distribution of the raw material (coke, ore) layer obtained by the profile meter, the gas composition distribution and the temperature distribution measured by the shaft sonde are input to the model as calculation conditions.

The "tuning parameter assumption" in FIG. 2 is a model parameter which is considered to be close to the current operating state selected from the accumulated model parameters of the past charge distribution model.

With respect to this model parameter, a charge distribution simulation is performed under the above-mentioned calculation conditions, and first, the gas composition distribution in the middle portion of the furnace is calculated according to the procedures (1) to (3) described above. It is judged whether the obtained gas composition distribution (calculated value) and the measured gas composition distribution in the middle portion match, and as a result, the calculated gas composition distribution in the middle portion and the measured value match. If not, the calculation is repeated while correcting the amount of change in the coke deposition angle in the middle part. As described above, the criterion for determining “match” is most preferably the matched state, but it may be the one determined to be the minimum by the operator according to the situation at that time. .

If the measured gas composition distribution in the middle portion agrees with the calculated value, the charge distribution simulation is performed again, and it is judged whether or not the measured value and calculated value of the gas composition in the central portion match. If they do not match, the calculation is repeated while correcting the deposition angle of coke in the center.

If the measured gas composition distribution in the central portion matches the calculated value, a charge distribution simulation is further performed to determine whether the measured gas composition in the peripheral portion matches the calculated value. If they do not match, repeat the calculation while correcting the ore deposition angle in the peripheral area.

By the above procedure, the calculation is repeated until the calculated value of the gas composition distribution in the furnace radial direction and the measured value match, and if they match, the result, that is, the coke deposition angle in the middle part, the central part The deposition angle of coke in and the deposition angle of ore in the peripheral area are output. The model parameters of the charge distribution model obtained by the above simulation are input to the parameter file, updated and stored, and added to the next model parameter selection target.

The above-mentioned charge distribution simulation is first carried out in the middle part of the furnace, and then in the central part and in the peripheral part, in order to control the charge distribution. This is because the influence of the fluctuation of the coke deposition angle caused by the collapse or inflow of the coke layer charged immediately before the charging of the ore is the largest. That is, the simulation is performed in order of increasing influence to control the layer structure of the furnace top charge.

Therefore, the charge distribution simulation may be carried out only in the middle part of the furnace, and although the prediction accuracy is slightly lowered, the layer structure of the furnace interior charge can be quickly predicted. . The method of the invention (1) above adopts such a simulation method. That is, in FIG. 2, the calculation is performed excluding the portion surrounded by the alternate long and short dash line, and only the deposition angle of the coke in the middle portion is corrected to predict the layer structure (distribution state) of the charge.

As a result of the calculation by the above-mentioned charge distribution prediction model, it is possible to accurately predict the layer structure (distribution state) of the charge at the top of the furnace after charging the raw materials, and based on that, the above calculation is performed. It is possible to calculate the gas flow distribution in the radial direction of the furnace. Then, the gas flow distribution can be appropriately controlled based on the difference between this gas flow distribution and the preset target gas flow distribution, and the operation can be stabilized. Note that the preset target gas flow distribution is a gas flow distribution determined according to the operation target, and the gas flow distribution is controlled by using a movable armor notch or a large bell stroke in the case of a bell-type blast furnace, In the case of a bellless blast furnace, the number of turns of the swivel chute and the chute angle are used.

The effects of the present invention will be specifically described below with reference to examples.

[0038]

EXAMPLE An example of a blast furnace having an inner volume of 2700 m ³ is shown below.

In the conventional example of Table 1, the amount of pulverized coal blown is 15
This is the case where the target gas flow distribution is obtained by controlling the distribution of the charge in the normal operation of 0 kg / pig t level.

In the comparative example, the amount of pulverized coal blown was 180 kg.
/ In the case of increasing the pig iron t, when changing the charging O / C at this time, in order to maintain the air permeability, in order to maintain the coke layer thickness of the cohesive zone part The input amount (coke base) was kept constant and the amount of ore charged was increased. However, a decrease in stave temperature and a decrease in static pressure in the lower part of the furnace wall were detected, and instability (slip) of local unloading in the peripheral part of the furnace occurred. This deterioration of the operating condition was determined by the conventional charge distribution prediction to be due to the shortage of the surrounding gas flow. Therefore, the operating condition was improved by strengthening the peripheral gas flow. However, the temperature and static pressure in the lower part of the furnace decreased further, and the instability of unloading increased further.

Therefore, the charging distribution control method of the present invention was applied to the examples. That is, firstly, the deposition angle of the coke in the middle part was changed so that the difference between the calculated value and the measured value of the gas composition distribution in the furnace radial direction was minimized, and then,
Similarly, the coke deposition angle in the center is changed so that the difference between the calculated value and the measured value is minimized, and then the deposition angle of the ore in the peripheral part is changed, and repeated calculation is performed to obtain the optimum value for each. Was done. Based on the resulting layered structure of the charge at the top of the furnace, the charge distribution control was performed again to obtain the target gas flow with the strengthened peripheral part.

As a result, the stave temperature in the lower part of the furnace increased, the unloading became stable, the increase in the peripheral gas flow was detected, and the operating condition improved.

In the comparative example, the operation state could not be improved because the amount of ore charged increased due to the increase of the pulverized coal injection amount of 30 kg / pig iron t. This is because the O / C in the peripheral portion was higher than expected and the peripheral gas flow was low because the gas flow was high. Therefore,
With the operation width performed to strengthen the peripheral gas flow, a sufficient peripheral gas flow was not obtained, but rather, the amount of collapse of the coke layer increased, resulting in a shape that suppressed the peripheral gas flow. It is probable that the lower furnace stave temperature could not be avoided and the operating conditions could not be improved.

[0044]

[Table 1]

[0045]

By applying the method for controlling the distribution of blast furnace top charge according to the present invention, the gas flow distribution of the blast furnace is properly controlled, and stable blast furnace operation can be performed even under high PC operation. it can.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a function of a charge distribution prediction model used in the method of the present invention.

FIG. 2 is a flowchart showing a calculation procedure of a charge distribution prediction model used in the method of the present invention.

[Explanation of symbols]

1: Large bell 2: Raw material 3: Armor 4: Iron raw material (ore) 5: Coke 6: Raw material falling width 7: Coke layer collapse 8: Center coke deposition angle

Continuation of the front page (56) Reference JP-A-9-111321 (JP, A) JP-A-8-60212 (JP, A) JP-A-11-106807 (JP, A) JP-A-4-350108 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C21B 5/00 311

Claims (2)

(57) [Claims] 1. In a blast furnace operation in which ores and coke are charged in layers, raw material charging conditions, air blowing conditions, and profile profile measurements on the surface of the raw material deposition layer are used to measure the radial direction of the furnace top.
Material surface shape, ore / coke ratio, and particle size distribution <br /> In calculating the structure and gas flow distribution of the raw material deposit layer, it was calculated based on the structure and gas flow distribution of the raw material deposit layer at the top of the furnace. In order to minimize the difference between the radial gas composition distribution in the furnace and the radial gas composition distribution measured in the upper part of the furnace, it was charged just before the charging of the ore in the middle part of the furnace. Calculated while correcting the deposition angle of coke,
Based on the difference between the obtained gas flow distribution and the preset target gas flow distribution , the movable armor notch
Stroke, number of turns of turning chute and shoot angle
A method for controlling the distribution of blast furnace top charge, which comprises controlling the furnace interior charge distribution by adjusting at least one of the degrees . 2. The correction of the deposition angle performed when calculating the structure and gas flow distribution of the raw material deposition layer at the furnace top,
The method for controlling the distribution of blast furnace top charge according to claim 1, wherein the deposition angle of coke in the central portion of the furnace is performed, and then the deposition angle of ore in the peripheral portion of the furnace is performed.