JPH01319616A - Method of operating blast furnace - Google Patents

Abstract

PURPOSE:To automatically administrate furnace conditions to a stable state by selecting blast furnace operating conditions from the respective ranks of furnace heat trends determined from a change in heat balance and the temp. of a molten iron and the information in the respective histories of the already existed operating conditions, etc. CONSTITUTION:The change in the heat balance and melting temp. determined by the heat balance model estimated by the heat balance in the lower part of the furnace are respectively segmented to prescribed ranges and the ranks of the furnace heat trends are determined. The operating conditions are previously set for each of the ranks of the furnace heat trends. The above-mentioned operating conditions are selected simultaneously from the change rate in the heat balance and the temp. of the molten iron at the time of deciding the furnace heat. The operating conditions are selected from the operating conditions before and after the above-mentioned operating conditions as a standard inclusive of said standard according to the information in the histories of the molten iron temp. to the decision of the furnace heat and the information in the histories of the already executed operating conditions including coke ratios, moisture, blast temps. and blast rates. The heat control of the blast furnace is executed precisely, automatically and adequately in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of operating a blast furnace, and more specifically, to a method of operating a blast furnace that uses a GT N machine to control the furnace heat of the blast furnace. The present invention relates to a method of operating a blast furnace that improves accuracy and automatically manages furnace conditions in a stable state based on the history of actions that have already been taken.

Prior Art Conventionally, as a method for systemically controlling the furnace heat of a blast furnace using a subtraction machine, the applicant of the present invention, G.
There are management systems for blast furnaces, such as the o-8tO1) system. However, although this system detects abnormalities in the blast furnace and suggests the necessary actions, its prediction accuracy is low, and when abnormalities occur continuously, continuous
There was a C-C that could not be used to give instructions for ln, and its scope of use was narrow.

In recent years, technology has been developed that uses AI (artificial intelligence) to incorporate the know-how of blast furnace operators into the system and improve the accuracy of predicting the furnace heat required for blast furnace operation. Publication No. 270708 and JP-A-62-270
As shown in Publication No. 712, 8 of furnace heat control and furnace condition detection
A system using a computer has been proposed.

The former is based on the furnace heat, hot metal temperature, tuyere, and slag.
! This is a system that makes judgments according to the dormitory's human judgment rules, estimates the furnace heat transition based on information obtained from various sensors, and takes actions to control the furnace heat based on this furnace heat level and furnace heat transition. The latter is a system that can diagnose slips and blowouts.

However, although the former can be highly evaluated in that the action is determined based on the furnace heat situation, there is a problem in that the furnace heat is determined by observing the hot metal temperature and the tuyeres, etc. Regarding temperature, disadvantages include the difficulty in setting the representative temperature to be used, and the inability to avoid individual differences in observation methods such as tuyeres.

Now, as a factor for evaluating the thermal condition of a blast furnace, the measurement results of the temperature of hot metal tapped from the taphole have conventionally been generally used. This hot metal temperature measurement differs depending on each steelwork, but it is usually carried out at a rate of about 7/1 hour at a time.Maintaining the hot metal temperature above a certain value is the key to maintaining smooth blast furnace operation. The reason for this is that CI) the hot metal temperature is the index that best expresses the thermal condition of the blast furnace; , it is impossible to continue operation. In other words, there is molten pig iron and slag in the blast furnace, and the temperature inside the furnace drops to fff, >'8 If the pig temperature decreases, its fluidity will deteriorate and it will be difficult to submit. Therefore, it is necessary to ensure the fluidity of the pig iron and slag. Although slag components have an effect on culm density, the influence of melt VL temperature is the most significant.

However, when determining the temperature of the melt R, as shown in Figure 6 (
a), (1) ) a) Yohi (C) shows the change in melt temperature over time, as well as the change in hot metal temperature over time during lap tapping and when deviation occurs between tags, (1) Initial stage of tapping Since the gutter is cold, the temperature is low (see Figure 6 (a)).

(2) At the time of the first tap (the first time the tap is tapped after a gutter that has only been used for a long time), the gutter is very cold, so the temperature of the hot metal rises very slowly (see Figure 6 (aJ)). ) During lamp tapping, the temperature on one side is low and the temperature on the - side is high (see Figure 6 (1)).

(4) When a taphole deviation occurs, the temperature of hot metal changes greatly depending on the taphole (see Fig. 6(C)).

Therefore, when evaluating the actual hot metal temperature, operators are responsible for determining the measurement timing.

In other words, at what timing and under what circumstances were the measurements taken? 1
! The operator estimates the true value (value measured without disturbance) by examining the I temperature value.

On the other hand, in order to evaluate (judge) the thermal state of a blast furnace based on the hot metal temperature using a computer, it is necessary to know the temperature of the hot metal to be evaluated at each judgment timing. is difficult to set.

Furthermore, when systematically controlling the heat level (furnace heat) of a blast furnace using a so-called computer such as an Expert 1 system or a process computer, it is recommended to use the hot metal temperature and the furnace heat index (furnace heat prediction). Common. The furnace heat index can be determined with a high level of precision because the various data that form the basis of it are continuously measured by each sensor, and there are few disturbances.

On the other hand, the hot metal temperature is subject to disturbances as mentioned above, and the measurement cycle is longer than the system's judgment cycle, making it difficult to ascertain the true temperature at that timing when evaluating the furnace heat. Met.

Therefore, when evaluating the thermal state of a blast furnace using a computer, it is impossible to set the temperature of hot metal to be evaluated.

In other words, when making a direct judgment based on the measured values, 1) measurement timing (how much time has passed since tapping), 2) condition of the gutter (new gutter, used gutter), and 3) condition of the hot metal. Degree of flow (thick or thin) 4) There is a problem that there is a large variation due to the deviation between tap holes, and that it cannot be used as a correct judgment.

In addition to the above-mentioned problems with the accuracy of furnace heat prediction, when deciding on actions to take to the blast furnace, it is necessary to consider the history of actions that have already been taken. If you do not decide the next action, there will be problems such as excess or deficiency of actions.
Well, there was no practical system for automatically slow-rolling the furnace heat in a blast furnace, and it was hoped that one would emerge.

Problems to be Solved by the Invention It is an object of the present invention to solve these problems, and specifically, the furnace heat control system of a blast furnace automatically adjusts appropriate operating conditions with a precision that can withstand practical use. The purpose is to provide a blast furnace operating method that allows instructions for changes, etc.

Means for solving the problem and its operation, that is, the present invention classifies heat balance changes and hot metal temperature found from a heat balance model that estimates the heat balance in the lower part of the furnace into predetermined ranges, and ranks the furnace heat trend. The operating conditions are set in advance for each furnace heat trend rank, and the operating conditions are selected from the heat balance change amount and hot metal temperature at the time of furnace heat judgment, and the >g temperature degree during the furnace heat judgment is determined. Based on the historical information and historical information of the previously implemented operating conditions such as carbon/coke ratio, humidity, air blowing temperature, and air blowing amount, -
The blast furnace is characterized in that the blast furnace operation is performed by selecting operating conditions from among the operating conditions before and after the C5 standard.

Therefore, the structure of these means and their operation will be explained as follows.

The present invention is a blast furnace operating method using a system with an overall configuration expressed by a flowchart shown in FIG. judge. Next, a primary action that matches this primary judgment is selected, and while the operator's know-how is reflected in determining the hot metal temperature and can be generally applied, the primary action is Past operations are compared to reflect the history of actions that have already been taken, and this comparison also employs the operator's know-how and generalizes it by embodying it.

Therefore, the final action instructions are usually as precise as or higher than the highly accurate actions performed by a skilled blast furnace operator, and automation of blast furnace operation is achieved here.

First, the determination of hot metal temperature will be described.

In a blast furnace, usually one or two tap holes are tapped intermittently or continuously, and the temperature of the hot metal is measured and evaluated.

In order to improve the accuracy of this evaluation, the present inventors summarized their experience in conventional operations, and as a result, they were able to estimate an accurate temperature by performing the following steps.

1) At the start of tapping (1) Let the hot metal temperature representative of the current tapping of the previous pig iron tap be the representative hot metal temperature of the current tapping.

(2) If tapping is stopped after the previous or two-previous tapping starts, compare the current representative hot metal temperature with the previous or two-previous representative hot metal temperature at the time of stopping the tapping, and set the higher one as the current representative hot metal temperature. Hot metal temperature.

2) When measuring hot metal temperature: (1) Determine whether or not the tap hole was used within a certain period of time (for example, 24 days) after the first tap.

CI) If it is the first tap, the representative hot metal temperature remains the same.

(II) If it is not the first tap, the next process is performed.

(2) Determine whether a certain period of time (for example, 90 minutes) has passed since the start of tapping.

If CI+a certain time or more, the measured value is taken as the representative hot metal temperature.

(II) Within a certain period of time, only when the measured value is equal to or higher than the representative hot metal temperature at that time, the constant value of λ is taken as the representative hot metal temperature.

(3) Judgment (1) Lap tapping R (Tapping from two tap holes) The higher of the representative hot metal temperatures for each tap is the hot metal temperature for evaluation.

(2) At the time of taphole deviation (when using two or more tapholes) (■)
[Current representative hot metal temperature - Previous representative hot metal temperature 1> Constant value (15°C) - Previous representative hot metal temperature Ko> Constant value (15°C) (Ill) [
Furnace heat index (this time) - Furnace heat index (previous time)] < constant value (15
"C) If the above three conditions (Il, (III), (III)) are satisfied, it is determined that there is a deviation, and only when there is a deviation, it is determined by the following equation.

Hot metal temperature for evaluation - 0.5X (representative temperature this time, representative temperature 10 times ago) (3) Other hot metal temperature for evaluation - If the temperature is set at or above the representative hot metal temperature at that time, the time and evaluation of an example of the example shown in Fig. 4 will be obtained. As shown in the graph without showing the relationship with the hot metal temperature for evaluation, the hot metal temperature for evaluation is continuously obtained by various corrections.

Note that the measurement results of the hot metal temperature at the initial stage of tapping and during lap tapping, such as Pl, P2, P3, and P4 shown in FIG. 4, are not the hot metal temperature for evaluation.

As described above, by using the data that defines the hot metal temperature, the hot metal temperature measurement results, which were conventionally only carried out in batches and which include various disturbances, can be used for evaluation of the thermal state of the blast furnace. It became possible to convert this into temperature, and this made it possible to process furnace heat continuously (regularly) using a computer.

Next, we will discuss the prediction of furnace heat.

Furnace heat prediction is determined from changes in the heat balance in the lower part of the furnace, and is performed as follows.

(1) Furnace heat prediction (△ [Q rank) 1) The definition of TO(jo) is shown as follows.

TQ: Heat balance in the lower part of the furnace based on 900°C.

TQ=01 +02- (Q3+04+05) (103
Kcal/l・p) Ql; Sensible heat of air (900°C base'$
) 02; Combustion of coke at the tip of the tuyere @ (CO basic graduate) 03
; Decomposition heat of feed moisture G4; Tsuru loss reaction G5; Stave heat removal (furnace lower part) Q1 = BV' X (BT-900) Xo, 335 (specific heat cal/Nm'-air) x
MoistxlozuX (BT-900)X22.4/1
8X0.449 (1120 (specific heat of (1)) xlO-3
Q2=BV' X (0,210 EO2 (Ch M conversion rate)
)×12/11.2+BV'xMoistxlO-'
x12/18) X 2450 (cal to combustion heat of C
/kg-C)X10-3 Q3=BV'XMOiStXlo-'X3185(
min [4 cal/kgH,, o) x 1O-3Q4
= C5ol x 3230 (cal
/kg ~c) 05-'-△Q (Stave heat removal 103K
cal/1()x10'/60/PiQ (ironmaking speed t/Mln) G1; Complete cutting of the furnace bottom.

BV': Air consumption unit (N m'/l-11) (EO
2) BT: Blow temperature ('C) Moist: Blow moisture (g/Nl113) C3OI:
The definition of the sol loss c(kq/1-p)2)ΔTQ(jo) is shown as follows.

jo, jo a...; Furnace heat judgment timing here.

a=3 to 11 1) -4 to 12 A rank table for furnace heat determination can be created based on the amount of ΔTQ and the amount of change from the reference value of the hot metal temperature.

Preferably, the accuracy can be further improved by further subdividing the above ΔTQ according to the variation and performing furnace heat prediction. This variation is determined by determining RΔ■0.

3) The definition of R△TQlo) is shown as follows.

Here, 11-1~5 c=1~6 4) The determination of Δ■0 rank is shown as shown in Table 1 by evaluating RΔTQ.

Table 1 (Note) The ranks -3, -2, . . . +2 in Table 1 indicate the ΔTQ rank (furnace heat prediction) in Table 2.

In addition, in the case of only △IQ, it is sufficient to classify them based on their personality.

In addition, the relationship between the hot metal temperature and △TO described above corresponds well as shown in Figure 2, and the transition of △TO (not shown in Figure 2 (a)) and the change in hot metal temperature in (1)) are similar. It can be seen that the accuracy is sufficient for predicting blast furnace heat.

2. Furnace heat determination The above hot metal temperature (11, M, T,) is changed from the standard value by the rank (P), and the furnace heat rank (Heto 0 rank) and Ma) ~
The furnace heat is determined by using the Ricks table, and the action type is determined according to each furnace heat. Table 2 shows one example.

Table 2 (Note) Table 2 does not show the following.

(I) Table value is action type, (TI) “None” is No Action, (III j
The action type arrangement on the table is variable (TV)
, T, ) x-1480~1500°C In addition, the action type indicates the amount of change in operating conditions that should be adopted for each furnace heat judgment rank, and is determined in advance in accordance with each furnace heat. An example is shown in Table 3.

Table 3 (Note) Table 3 shows the following.

CI) Old and Moist can be regarded as top measures, etc., and which one implements the other.

(II) BV is the wind reduction ratio (%) relative to the specified value (Ill
) + indicates rising, - indicates falling.

Here, (19 B■; Blow temperature (°C) Molst: Blow humidity ((1/Nm')) 13v; Power of air flow (%) C1l; Coke (kg/l-Pig) Table action The amount can be changed.As described above, the action type is determined according to the furnace heat judgment, and the action item and action amount, which are preset according to the action amount, are used as the primary action instruction.

In addition, in order to further improve accuracy, the following points should be made sparingly regarding the hot metal temperature.

(1) Hot metal temperature used for furnace heat determination - previous hot metal temperature ≧81 (2) Hot metal temperature used for furnace heat determination - previous hot metal temperature ≧a2 Hot metal used for furnace heat determination; each time - previous hot metal temperature! 1i: temperature≧83, where (1) or (2
), the hot metal temperature rank used for evaluation will be lowered by 1 rank because it is on the rise.

Here, it is assumed that al>82>a3, and the values 81 to 83 correspond to the hot metal ranks in Table 2. For example, the hot metal rank classification in Table 2 is divided into small parts (that is, the 81 to a3 values are also small, and vice versa.The reason for increasing this rank is that the furnace heat rise takes a long period of time, Set the trend to increase by one rank.

Furthermore, the action type will be revised in consideration of the increase in air temperature over the past 8 to 16 hours. In other words, an operation in which the hot metal temperature cannot be maintained without abnormally increasing the air blowing temperature can be considered to be unstable. In such a case, the furnace condition will recover more quickly if a larger action is taken to reduce the air than to further raise the air blowing temperature.

Furthermore, if there have been many wind reduction actions in the past, it would be faster to take a larger action, the cylinder reduction action.

Therefore, in the above case, when the action type force selected from Table 3 (not including wind reduction and cylinder reduction), it is preferable to respond by increasing the action type rank.

For example, when the increase in air temperature [1] is large, there is no action item for the amount of air flow for types 3 and 4.

Therefore, the rank is increased to type 5.

There is no cylinder reduction action item for lifting platforms, types 6 and 7, which have adopted wind reduction actions in the past.

Therefore, the rank is increased to type 8.

By restoring the baby as described above, the furnace heat can be recovered quickly.

3. Modify the action instructions (1st stage) issued in the final action furnace heat judgment (1st stage) according to the above matters, examine this modified action and the history of actions that have already been carried out, and determine the optimal one at that point. Determine final action instructions.

First, regarding the air temperature, it is preferable to include the following action history. When taking action to raise or lower the blast temperature, in addition to the amount and elapsed time of past changes in the blast temperature, action items such as coke ratio and blast moisture that have thermal effects are also included. The coke ratio is determined by taking into account the amount of previously implemented actions and the period of impact on the blast furnace. This is used to determine the final action. Similarly, the humidity of the blast air is differentiated based on the delay time that affects the reaction in the furnace and used to determine the final action. - To give an example, the period for changing the coke ratio can be set to 8■ as the raw material cycle time (4), and about 114 as the lag time for the ventilation moisture. It may be set based on the specific characteristics of the equipment, such as load level and furnace volume.

Next, a determination flowchart for issuing a final action instruction as shown in FIG. 3 by comparing with the action history will be explained.

The flowchart not shown in Figure 3 is (△CR(8H): Change in coke ratio for 8 hours, △Mo1st(ill): 1
The time is the change in air humidity, BT↓(1st): BT lowering width of the primary action, BT↓(8H): 8 hours BT lowering width, BT↓(16+1J: 16 hour BT lowering width, B
T↓(R end): (BT lowering width of the final action, where BT↓(final)≦81) This is a flow diagram for determining the BT lowering instruction of the final action, and here, △CR1△M
A judgment is made based on whether the revision is stable by comparing which of o1st with the amount of change taken during 8 and 1 hour, respectively.

The OR and Mo1st taken in the past are judged, and if these actions have been implemented, the judgment is made by comparison with large changes in the past history, and vice versa, by comparison with small changes, and the al , ~a5 values are set to avoid sudden changes in furnace conditions and to detect long and short-term changes in furnace conditions, and 1a11<la2 l<1a31<laq l<las
It is shown by the relationship of l.

Note that al is a control value for avoiding sudden changes in the furnace condition, and the others are control values for determining the furnace condition.

In addition, Fig. 3 can be similarly used to determine the BT increase instruction, and the values to be compared in the judgment flow diagram of Fig. 3 are established by giving an inverse unequal table, and each management value is a positive value. All you have to do is take the value.

In addition, for the coke ratio, it is preferable to include the following action history, and the increase in the coke ratio, that is,
The cylinder reduction instruction takes into account the amount of change taken in past actions and the elapsed time since the action. This elapsed time is based on whether or not the changed part taken in the past action remains inside the furnace.) If it is within the retention period, the retention period is calculated from the amount of the first individual action. The final action amount is determined by reducing the amount of actions taken within.

In addition, the amount of increase in the first CR - 1st action - △CR (8
) 1), and the amount of increase in CR is also determined by setting the judgment value to the amount (remaining) taken in the past, and when it is above the judgment value, the above judgment is applied, and when it is below the judgment value, it is based on the condition of the furnace. Since the change can be said to be relatively small, the operation may be performed by increasing the amount of primary action. By using this determination value as a value smaller than the action amount classification shown in Table 3, detailed operation selection can be made within the action type.

Next, changing the air flow rate is the method that can be reflected in the furnace condition most quickly, and the stabilizing power of reflecting the furnace condition against the change (it only needs to be determined including the amount of change within the latest possible 211, and the first action is The final action is determined by subtracting the air volume changes adopted in the past 211 from the air volume reduction instructed in .

Example Examples will be described below.

FIG. 5 shows an example of furnace heat control according to an embodiment of the present invention. Ding, (J o
), Δ■0 rank, air blowing temperature, air blowing amount a5, and a graph showing the relationship between the air blowing temperature (BT) of the primary determination.

1) First, 11. shown in FIGS. 4(a) and (1)). M
, T, (jo) and △King Q rank in Figure 5(e)
The primary determination (blow temperature) shown in is presented.

2) Next, the primary determination is corrected based on the action history, and instructions are given to change the air blowing temperature and air blowing amount as shown in FIGS. 5(C) and (d).

3) The action at 7 o'clock is particularly noteworthy.

(■) Primary judgment BT-1-20℃ (Action 4 type) (
II) △BT (8H) = +30°CCI) and (I
I) to action amount BV-30ON m'/M i
n (action type 5) is instructed.

4) As a result, the temperature of the hot metal recovered around 8 o'clock.

5) This series of actions had almost the same accuracy as the operator's actions.

<Effects of the Invention> As explained above, the present invention classifies the heat balance change and hot metal temperature found from the heat balance model that estimates the heat balance in the lower part of the furnace into predetermined ranges, determines the furnace heat trend rank, and The operating conditions are set in advance for each furnace heat trend rank, and the operating conditions are selected from the heat balance change amount and hot metal temperature at the time of furnace heat determination, and the history information of the hot metal temperature and coke ratio during the period leading up to the furnace heat determination, The blast furnace is operated by selecting operating conditions from the previous and subsequent operating conditions including the reference, based on the operating conditions according to historical information of previously implemented operating conditions such as humidity, air temperature, and air flow amount. That is.

Therefore, the following effects were confirmed by operating the blast furnace using the method of the present invention.

1. Roll h (now possible) to the furnace heat controller 1 equivalent to a high-level operator.

2. Complete standardization of operational actions has been achieved, significantly reducing variations between operators.

3. There was no significant drop in furnace heat, and the resulting reduction in blast furnace production was eliminated.

4. The quality of hot metal has become stable.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the overall configuration of an example of a furnace heating system according to the present invention, and FIGS. A graph showing the relationship between hot metal temperature and furnace heat index, Figure 3 is B of the final action.
T"I: Flowchart of determination of descending instruction, FIG. 4 is hot metal for evaluation of the example of the present invention; Time flow diagram showing the temperature measurement method, FIG. 5(a), (1)), (C ), (d) and (
e) is a time flow diagram showing a detailed explanation of the present invention, and Figures 6(a), (1]) and (C) are respectively changes over time in hot metal B degree during blast furnace tapping and lap tapping. FIG. 7 is a graph showing changes and deviations between taps. FIG.

Claims (1)

[Claims] 1) Classify the heat balance change and hot metal temperature found from the heat balance model that estimates the heat balance in the lower part of the furnace into predetermined ranges, determine furnace heat trend ranks, and set operating conditions in advance for each furnace heat trend rank. , select the operating conditions based on the heat balance change amount and hot metal temperature at the time of furnace heat determination, and select the history information of hot metal temperature and the existing operating conditions of coke ratio, moisture, air blowing temperature, and air blowing amount until furnace heat judgment. A method for operating a blast furnace, characterized in that, based on the operating conditions, the operating conditions are selected from among the operating conditions before and after the operating conditions including the reference, and the blast furnace is operated.