JPH09111321A - Method for controlling distribution of charging material from furnace top of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To operate a blast furnace in high pig iron producing ratio by utilizing a correlation between a bellless mode condition and a charged material layer thickness distribution in a furnace to make a necessary furnace gas flowing distribution at a high accuracy. SOLUTION: A relative layer thickness ratio of ore/coke is actually measured at the arbitrary position along the radial direction in the furnace. The correleration between the obtd. relative layer thickness ratio and a bellless strength ratio is mapped from the past actual furnace data. The optimum bellless pattern is selected by using this correlation relational graph and the value of an average dropping positional index of ores is charged. Flat-state of a coke terrace is confirmed by using a predicting model of the charging material distribution and the concrete charging pattern is selected. Charging condition of the bellless charging mode is decided according to the selected pattern. Whether the decided condition is suitable or not, is judged by the correlation relational graph, and when the difference exists, the value of the average dropping positional index of the coke is changed in the increasing direction. Further, as necessary, the average dropping position of the ore is finely adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distribution control method for quickly and accurately selecting a charging pattern for a top charge in a bellless blast furnace operation in which ores and coke are charged alternately.

[0002]

2. Description of the Related Art In a bellless blast furnace, an operator qualitatively evaluates the gas flow distribution and furnace heat load based on information from various sensors installed in the blast furnace and changes the tilt pattern of the distribution chute. Controls the gas flow distribution in the furnace. However, since the quantitative relationship between the gas flow distribution obtained from the sensor information and the control amount by the distribution chute has not been adequately grasped, the tilt pattern of the distribution chute must be changed and the subsequent fluctuations in the gas flow distribution. The thickness of the charge layer is controlled by a trial-and-error method in which a changing operation is further added according to the trend. Therefore, it is not easy to match the actual gas flow distribution with the desired distribution for the reactor conditions, and it is necessary to adjust the distribution over a long period of time to obtain the target gas flow distribution. Therefore, in Japanese Unexamined Patent Publication No. 2-182815, a knowledge engineering system is used to determine the gas flow distribution state in the radial direction of the furnace, and a charge distribution prediction model calculation is performed under a plurality of conditions based on online data at that time. , The method of selecting the optimal shoot tilt pattern from the calculation results is introduced. Specifically, when determining the distribution of gas flow in the radial direction in the furnace, the radial direction of the furnace is divided into three regions, the central part, the intermediate part, and the peripheral part, and the present status is calculated using a triangular diagram showing the gas flow ratio. The deviation between the gas flow distribution state and the target value calculated by the charge distribution prediction model calculation is calculated and used to set the optimum conditions for the subsequent shoot tilt pattern.

[0003]

The hit rate of the controlled variable by the above-mentioned method greatly depends on the accuracy of the mathematical model for predicting the distribution of the charged material, and the gas flow distribution is simply represented by a triangular diagram. Not always accurate enough.
In addition, it is not possible to clarify the direction of long-term charge distribution actions. In addition, the air flow rate and O
It is necessary to strengthen the central gas flow to reduce the ventilation resistance in the furnace when the / C ratio rises or when the operation shifts to high PC blowing operation, which is a high O / C condition. In this case, since more ore layers having a smaller angle of repose than the coke layers are stacked on the coke terrace, the stacking state becomes unstable, and the collapse of the coke layer and the inflow of a large amount of ore toward the center of the furnace occur. It tends to occur. As a result, the reproducibility of the deposition profile for each charging charge tends to decrease. Therefore,
In order to obtain the required gas flow distribution using the charge distribution prediction mathematical model, it is necessary to consider destabilization phenomena such as coke collapse that occurs in the actual furnace. However, no practical charging control incorporating the destabilization phenomenon has been proposed,
It is difficult to easily and quickly obtain the gas flow distribution required according to the furnace conditions. The present invention has been devised to solve such a problem, and by utilizing the correlation that unifies the relationship between the bellless mode condition and the furnace interior inlet layer thickness distribution, the required furnace The purpose is to make the gas flow distribution with high accuracy and operate the blast furnace with a high tap ratio.

[0004]

In order to achieve the object, the charge distribution control method of the present invention uses a profile meter provided at the top of the blast furnace to detect ores / coke at a plurality of locations along the radial direction of the furnace. The measured layer thickness ratio is calculated and the ore of the entire charging raw material /
The relative layer thickness ratio of the measured layer thickness ratio to the average layer thickness ratio of coke is calculated as the relative layer thickness ratio at the plurality of locations, and the bellless strength ratio and the relative ratio represented by the ratio between the coke average drop position and the ore average drop position. The correlation with the bed thickness ratio is obtained in advance from multiple past actual furnace data with different charging conditions, and when changing the bellless charging pattern, the relative at multiple locations expected from the bellless strength ratio at the time of change planning When the layer thickness ratio differs from the actual relative layer thickness ratio at a plurality of locations, the coke average drop position is further finely adjusted. That is, the charge distribution is controlled according to the flow of FIG. First, the relative layer thickness ratio of ore / coke at any position along the radial direction in the furnace was found based on actual measurement, and the correlation between the obtained relative layer thickness ratio and the bellless strength ratio was calculated from past actual furnace data. Map it. The optimum bellless charging pattern is searched using this correlation diagram, and the value of the average drop position index of the ore is changed. Then, the flat state of the coke terrace is confirmed using the charge distribution prediction model, a specific charging pattern is selected, and the change condition of the bellless charging mode is determined according to the selected pattern. The suitability of the determined conditions is determined by whether or not there is a measured value of the profile meter on the line of the correlation diagram,
When there is a difference, that is, when the coke layer collapse has occurred, the value of the average drop position index of coke is changed to increase, and the average drop position of the ore is finely adjusted if necessary.

A plurality of patterns set by combining the tilt angle of the distribution chute and the number of turns are indexed in a format capable of expressing the average falling position of coke or ore. Then, based on a plurality of past actual furnace data with different charging conditions, the relative ore layer /
As a correlation with the thickness ratio of the coke layer, the relationship between the bellless mode condition and the furnace interior charge layer thickness distribution is unified and standardized. The bellless charging pattern is changed by the following actions. For example, when coping with an increase in the ore / coke ratio of the entire charging raw material at the initial stage of start-up of fire, transition to a high PC blowing operation, etc., it is possible to suppress or strengthen the decrease of the central gas flow in the furnace. It is necessary to reduce the ventilation resistance. In this case, the charging change pattern is planned based on the correlation that unifies the relationship between the bellless mode condition and the furnace interior charge layer thickness distribution, and the relative layer thickness ratio at the expected multiple locations and the relative layer thickness at the actual multiple locations are planned. When there is a difference in the ratio, the coke average drop position is finely adjusted. As a result, it is not necessary to control the charge layer thickness distribution by trial and error, and the gas flow distribution preferable for the furnace condition can be quickly and accurately selected.

Several methods such as changing the amount of coke base and changing the stock line are adopted for controlling the charge layer thickness distribution in the bellless blast furnace, but the most quantitative and highly flexible means are as follows: This is a change of the bellless mode set by a combination of the tilt angle of the distribution chute and the number of turns. Therefore, a case where the charge layer thickness distribution is controlled by the combination of the tilt angle of the distribution chute and the number of turns will be described. The charging pattern is, for example, when the coke and the ore are sequentially distributed into the furnace in the form of C02 dump 1 charge charging and the number of chute turns per dump is 12.
It is expressed by a combination of numerical values such as 7 ₂ 9 ₃ 11 ₃ 13 ₄ and O 7 ₃ 9 ₃ 11 ₃ 13 ₃ . Where C7
₂ 9 ₃ 11 ₃ 13 ₄ means C is an acronym for Coke, and one notch dump of the coke is rotated by 7 notches and 2 turns, 9
It shows that the coke is charged in a total of 12 turns of 3 notches, 11 notches and 13 notches. The notch is a numerical value representing the tilt angle attached to the distribution chute. The larger the numerical value, the more the charging material is charged to the center side of the furnace, and the smaller the numerical value, the more to the furnace wall side.

When evaluating a plurality of patterns by this expression method, it is inconvenient to distinguish them at first glance. Therefore, the bellless mode condition is used as an index and given by the following expression. This index is also useful for comparing data from two or more blast furnaces with different bellless charging devices and different furnace mouth sizes. Also, when collecting past data of a plurality of cases with different charging conditions, data of other blast furnaces can be taken in. Average drop position index of coke or ore = Σ [(t / r)
Xn] / N bellless strength ratio = (average drop position index of coke) /
(Average drop position index of ore) where t: SL of raw material falling trajectory at each notch
The intersection with 0m and the distance from the furnace wall n: The number of swiveling in each notch N: The total number of swiveling r: The radius of the furnace opening

On the other hand, the charge layer thickness distribution at a plurality of points along the radial direction in the furnace can be measured by a contact type (mechanical) or non-contact type furnace top profile meter using a microwave, a laser or the like. It is quantified by measuring the layer thickness ratio between the coke layer and the ore layer formed as a result of charging the raw material into. Also, when arranging past actual reactor data,
By collecting data as the relative layer thickness ratio represented by the following formula, data having different ore / coke ratios of the entire charging raw material can be evaluated by the same standard. Relative bed thickness ratio at any location = (Ore bed thickness at any location measured by profile meter) x (Average bed thickness per 1 dump of all charging coke) x (Coke at any location measured by profile meter) Layer thickness) ^-1 x (Average layer thickness per 1 dump of all charged ore) ^-1 Based on the data obtained in this way, take action according to the actual furnace conditions and determine the required gas flow distribution. obtain.
For example, when shifting to a high PC blowing operation which is a high O / C condition, the amount of ore flowing into the furnace center increases as the amount of ore having a smaller repose angle than coke increases. The surrounding gas flow tends to be strong. Further, when the blast rate and the O / C ratio at the initial stage of the ignition start up, it is necessary to sufficiently grow the central gas flow in order to ensure the air permeability in the furnace in order to stabilize the start up. Therefore, the charge distribution is controlled based on the above-mentioned index to strengthen the gas flow in the center of the furnace.

[0009]

[Embodiment] An embodiment in which the present invention is applied to an action of changing a charging pattern in an initial stage of setting fire is described.
As shown in Fig. 2, a flat coke terrace L with a predetermined length is used to strengthen the central gas flow at the initial stage of firing.
It is necessary to have a charge distribution that has formed, and the ore swing is directed. Therefore, as shown in FIG. 3, on the triangular diagram in which the radial direction in the furnace is divided into three regions of the central part, the central part and the peripheral part, the gas flow distribution ratio obtained from the charge distribution prediction model is shown. The calculated values were plotted, and the action of changing the charging pattern in the periods 1 to 10 was performed using the movement of the predicted value as an index. In addition, in FIG. 3, the calculated values of the gas flow distribution after the period 11 described in FIG. 4 to which the present invention is applied are also shown for reference. In the periods 1 to 11, the ore / coke ratio was actually measured at an arbitrary position along the radial direction in the furnace. Fig. 4 shows the result of arranging the relative value of the ore / coke ratio in relation to the bellless strength ratio set in the actual furnace. The bellless strength ratio in FIG. 4 is expressed by (average drop position index of coke) / (average drop position index of ore).

When the periods 1 to 11 are classified by the length of the coke terrace, the periods 1 to 9 are short terraces and the periods 10 to 11 are
Could be divided into long terraces.
In particular, from the period 1 onwards, when the ore swinging action is mainly used without changing the coke terrace length so much, the state of ore loading on the coke terrace L becomes unstable in the period 9 and the center of the furnace becomes unstable. The flow of ore into the direction occurred.
As a result, it is shown in FIG. 4 that the relative layer thickness ratio at the furnace wall side point (4) decreases and the relative layer thickness ratio at the furnace center side point (2) increases. In the action of changing the charge layer thickness from the period 5 to the period 6 for strengthening the central gas flow, the actual result of FIG. 4 is in the opposite direction to the central gas flow strengthening in comparison with the prediction according to FIG. This shows that the conventional prediction of only the charge distribution control means is not sufficient. Also, as seen in the action of changing the charge layer thickness distribution from the period 9 to the period 10 in which the coke terrace length is greatly changed to suppress only the coke collapse phenomenon under the condition that the gas flow distribution is constant. However, it was not possible to hit the target only by using the charge distribution prediction model, and the air permeability in the furnace decreased significantly.

Therefore, the bellless charging pattern was adjusted by means according to the flowchart shown in FIG. In period 11, the collapse phenomenon was suppressed and a central gas flow type flow velocity distribution excellent in air permeability could be obtained. Incidentally, the specific conditions of the bellless charging pattern from period 8 to period 11 are as shown in Table 1. According to the means of the present invention, the pattern change action from the period 8 to the period 11 is at the stage of the period 9 in which the coke collapse occurs as shown in FIG. 5, and the pattern change to the next step goes through the forthcoming publication 10. It is understood that the period 11 can be searched for without any search. The actual results of the actual furnace in the periods 1 to 11 are arranged by the influence of the bellless strength ratio on the air flow rate and the K value, and are shown in FIGS. 6 and 7, respectively. Here, the K value is an index representing the ventilation resistance in the blast furnace by removing the influence of the air flow rate, and the air flow pressure is P _B
(G / cm ² ), the furnace top pressure is P _T (g / cm ² ), and the Bosch gas flow rate is V _BOSH (Nm ³ / min), K =
It is represented by (P _B ² −P _T ² ) / V _BOSH ^1.7 . This K value is
It is an effective index for directly evaluating the state of the distribution of the contents inside the furnace. As a result of changing the bellless charging pattern to the period 11, the ventilation resistance in the furnace was reduced as shown in FIGS. 6 and 7, and the operating rate at the beginning of the firing plan was achieved.

[0012]

[0013]

As described above, in the present invention, when the bellless charging pattern is changed, the relative ore / coke relative layer thickness ratios at a plurality of locations in the radial direction in the furnace, which are obtained in advance from past actual furnace data. By finely adjusting the average coke drop position using the correlation between the strength ratio and the bellless strength ratio, it becomes possible to quickly and accurately select the required gas flow distribution according to the changed furnace conditions. . This method
Since it is not necessary to control the layer thickness distribution of the charge by trial and error, operation management becomes easy and it becomes possible to operate the blast furnace at a high tap ratio.

[Brief description of the drawings]

FIG. 1 is a flow for selecting an optimum bellless charging pattern according to the present invention.

[Fig. 2] Distribution of charging material near the furnace top

[Fig. 3] Triangular diagram divided into a central part, an intermediate part and a peripheral part along the radial direction in the furnace

FIG. 4 is a graph showing the relationship between the actual value of the relative layer thickness ratio of ore / coke at an arbitrary position in the radial direction in the furnace and the bellless strength ratio set in the actual furnace.

FIG. 5 is a graph showing a prediction change action when the present invention is applied to a bellless charging pattern change from period 8 to period 11.

FIG. 6 is a graph showing the effect of bellless intensity ratio on air flow rate.

FIG. 7 is a graph showing the influence of bellless strength ratio on K value.

Claims (1)

[Claims] 1. A method for controlling a charge distribution of a bellless type blast furnace when coke layer collapse occurs, wherein ore / coke measurement layers are provided at a plurality of locations along a radial direction in the furnace by a profile meter provided at the top of the blast furnace. The thickness ratio is calculated, and the ratio of the measured layer thickness ratio to the average ore / coke average layer thickness ratio of the entire charging raw material is calculated as the relative layer thickness ratio at the plurality of locations, and the coke average drop position and the ore average drop position are calculated. The correlation between the bellless strength ratio represented by the ratio and the relative layer thickness ratio is obtained in advance from a plurality of past actual furnace data with different charging conditions, and when the bellless charging pattern is changed, when the change is planned. Blast furnace furnace characterized by finely adjusting the average coke drop position when there is a difference between the relative layer thickness ratio at multiple locations expected from the bellless strength ratio and the actual relative layer thickness ratio at multiple locations Summit Control method of distribution of charge.