JPH02221307A - Method for evaluating furnace heat in blast furnace - Google Patents

Abstract

PURPOSE:To accurately grasp the necessity of a control action in the specific iron tapping at the past time from furnace heat level and pre-fixed rule by obtaining the converted molten iron temp. from the molten iron temp. in the blast furnace operation and obtaining the plural past molten iron temp. representative values and each furnace heat level, respectively, based on the above obtd. converted molten iron temp. CONSTITUTION:At the time of producing the molten iron in the blast furnace, at first the converted molten iron temp. is obtd. at this time except the cases executing temp. raising action and temp. dropping action from the actual molten iron temp. at the time of tapping the molten iron. Successively, based on this converted molten iron temp., (n) pieces of the molten iron temp. representative values at the past (n) times of the molten iron tapping, are obtd. and each furnace heat level of the (n) pieces of the representative temp. values is obtd. with membership function, and by obtaining the necessity of the control action at the time of tapping the molten iron (m) times (m<n) before with a fuzzy inference from the pre-fixed rule and the furnace heat level, the quantitative furnace heat level is decided in comparatively short time, and the furnace heat is always evaluated at good accuracy regardless of the temp. raising and the temp. dropping actions.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a blast furnace heat evaluation method for stable blast furnace operation.

(Conventional technology) Using a knowledge base from information obtained from temperature sensors, etc.
The conventional blast furnace furnace heat evaluation method for inferring the furnace heat level is 5ICE '88 27th Academic Conference Proceedings J
There is a method disclosed in "Learning Function in S60-3 r Blast Furnace Furnace Heat Expert System" page 627.628.

The expert system disclosed here constantly monitors the controllability of the blast furnace control system using sensors, and if the controllability deteriorates, it learns by changing the rules of the knowledge base in the system and controls the system. Maintains good quality.

The method for determining the controllability of this expert system is as follows:
The blast furnace furnace heat evaluation method is performed as shown below.

In other words, by accumulating operational results over the past several months, we determine the maximum hot metal temperature (
The control state of the furnace heat is evaluated based on the criteria shown below, using the index (which is most representative of the furnace heat, but is not obtained until 2 to 4 hours have passed after the start of tapping) (see Fig. 8).

■ Has the tap maximum WJ pig concentration reached the target temperature? ■
The fluctuation in the maximum tap temperature of hot metal was within the target. In Figure 8, there is no abnormality in case A, and in case B.
~Case D determines that some kind of furnace heat abnormality has occurred.

(Problem to be solved by the invention) The conventional blast furnace furnace heat evaluation method is performed as described above.
Cases A to D were only evaluated by determining whether the tap representative hot metal temperature reached the target temperature and whether the fluctuation was within the target value. Therefore, there was a problem in that the furnace heat level could not be quantitatively evaluated.

For example, when the tap representative hot metal temperature changes near the target temperature, there is a problem in that the furnace heat evaluation becomes completely opposite due to a minute change.

In addition, in order to evaluate the furnace heat level from the tap representative hot metal temperature obtained by accumulating operational results over the past several months, we also investigated whether control actions such as heat raising action and heat lowering action should have been taken at the time of tapping. There was a problem that it could not be determined accurately.

Furthermore, since the tap representative hot metal temperature obtained by accumulating operating results over the past several months is used as the criterion for furnace heat evaluation, there is a problem in that it takes a long time to obtain the evaluation.

In addition, even if the tap representative hot metal temperature rises or falls due to the influence of operational actions (heating action, cooling action), furnace heat evaluation is performed in the same way as when no operational action is taken, so accurate There was a problem that it could not be said that furnace heat evaluation was performed.

This invention was made to solve the above-mentioned problems, and it is possible to quantitatively determine the furnace heat level in a relatively short period of time, and to accurately determine the need for control actions at a specific tapping time in the past. The purpose is to obtain a method for evaluating blast furnace heat that can be understood.

(Means for Solving the Problems) The blast furnace furnace heat evaluation method according to the present invention includes a first step of determining a converted hot metal temperature by removing the effects of heat raising action and heat lowering action from the actual hot metal temperature; a second step of determining n hot metal temperature representative values in the past 0 taps based on the converted hot metal temperature; and a third step of determining the furnace heat level of each of the n hot metal temperature representative values using a membership function. m(
and a fourth step of determining the necessity of the control action at the time of previous tapping (m<n) times.

(Operation) In the third step of the present invention, the furnace heat level of each of the n hot metal temperature representative values is determined by a membership function, so that the furnace heat level can be determined quantitatively.

Furthermore, the typical value of hot metal temperature is calculated based on the converted hot metal temperature obtained by removing the influence of heat raising and cooling actions from the actual hot metal temperature. There are no different evaluations.

(Example) Hereinafter, a blast furnace furnace heat evaluation method, which is an example of this difficult-to-understand method, will be explained. In addition, in this example, the past three times of tapping A1~
The necessity of the control action at A2 during tapping is determined from the hot metal temperature representative values T and -T3 at A3.

A. Calculation of molten pig iron temperature First, by using the actual action change predicted value Z(t) during the past three tapping times A1 to A3, the actual molten pig iron temperature y(t> From, operation action (heating action).

Converted hot metal temperature V with the influence of heat reduction action) removed
' Find (t).

Below, regarding the actual action change prediction value Z(t), the first
This will be explained in detail with reference to the figures. Actual action change predicted value Z (
t) is! a This is a predicted value of the amount of change in hot metal temperature at time t when the operation action of temperature and humidity control is performed.

As shown in FIG. 1, when an operational action is taken at time 0, its response (the force that affects the hot metal temperature V(t)) gradually appears.

Based on this change in response, the predicted value of the change in hot metal temperature after performing the operational action is the predicted value of actual action change Z (
t). This actual action change predicted value Z(t) is
It is calculated by determining the response of hot metal temperature to actions such as wind temperature and *humidity using a mathematical model or data analysis. Actual action change prediction using mathematical model 1111
1IZ(t), for example, Mi “Development of unsteady blast furnace simulation program” (“Tetsu to Hagane J 1m12.
vo173.8825 (1987, page 89).

Using the action change prediction value Z(t) described above, the following (
Using equation 1), the converted hot metal temperature V' (t), which is the predicted value of the hot metal temperature when the influence of the operational action is removed, that is, when no operational action is performed, is obtained.

It shows the change in pig iron temperature y'(t) over time. Note that if there is no influence from the operational action, the predicted actual action change value will naturally be Z(t)-0.

B. Temperature 1 Measurement of the table value Then, based on the converted hot metal temperature y'(t), each hot metal temperature representative value T at the past three times of tapping A1 to A3
1 to T3 (T1 is the oldest and T3 is 11t newer). The hot metal temperature representative values T1 to T3 include a maximum temperature, an average temperature, and the like.

Next to C-, the furnace heat evaluation points F1 to F3 of the hot metal temperature representative values T1 to T3 are determined from the membership function shown in FIG.

For example, if the hot metal temperature representative value T1 is 1490°C, the furnace heat evaluation point F1 of the hot metal temperature representative value T1 is LL-0,0,LM
= 0.3. M-0,7,HM-0,0,HH-0,
It becomes 0.

In addition, in FIG. 3, LL, LM, M, HM.

HH is a furnace heat evaluation parameter, and each parameter is LL...Low 1M...slightly low M...Stable HM...Slightly high HH...high It means. These parameters LL, LM.

M, HM, and HH have fitness values of 0 to 1. Further, the shape of the membership function shown in FIG. 3 can be changed depending on the blast furnace, remote control temperature, etc.

D. Intermediate Tuna Decision - Compare the furnace heat evaluation points F1 to F3 obtained in this way with the furnace heat evaluation rules created in advance (see Table 1),
If successful, an intermediate conclusion C1 is obtained.

Verification is successful when all of the parameters (LL, LM, M, HM, HH) shown in conditions F1 to F3 have positive values. In addition, in Table 1, D,
DM, N, uM, and U are parameters indicating the necessity of control action, and each parameter is as follows: D...Heat lowering action DM...Weak heat lowering action N...No action required UM... Weak heating action U: Indicates heating action.

(Hereinafter, blank space) Table 1 Furnace heat evaluation rules Below, the rules of Table 1 and furnace heat evaluation points F1 to F are given as examples.
3 will be explained. For example, if the tap hot metal temperature representative value T = T2 - 1460°C and T3 = 1515°C, the furnace heat evaluation point F1. F2 is [LL=1.0. HM-HH
-LM=M-0,0], and the furnace heat evaluation point F3 is [HH
-0,3,HM-0,7,M=LM-LL-0,0]. Consider a case where such furnace heat evaluation points F1 to F3 are compared with the rule of Nα121. In this case, the condition part F1 = LL = 1.0 F2 - LL = 1,0 F3 - HH - 0,3 and all the furnace heat evaluation points F1 to F3 obtained positive conformity, so the verification was successful. , control action N, which is the conclusion of the rule in order 121, is derived as an intermediate conclusion C1. At this time, the suitability of the control action N is 0.3 for the condition part F3, which is the minimum suitability of the condition part.

Then, the control action parameter D shown in FIG.
The membership function of control action N is extracted from the membership functions of DM, N, UM, and LJ, and as shown in Figure 5, the membership of intermediate conclusion C1 whose upper part is cut off with a fitness of 0.3 is obtained. Create function 81 (y). In FIGS. 4 and 5, y is the control action level, and if it is positive, it indicates the necessity of heat-raising action, and if it is negative, it indicates the necessity of heat-lowering action.

Perform the above verification for all rules in Table 1,
If the matching is successful, the membership function B(l) of the intermediate conclusion C1 is created as shown in FIG.
In the above example, in addition to NQ121, matching of rules Nα122 is successful. In this case, the condition part is Fl-LL-1,0 F2=LL-1,0 F3-HM-0,7, and the control action UM, which is the conclusion of the rule of Nα122, is derived as the intermediate conclusion C1. At this time, the suitability of the control action UM becomes 0.7 for the condition part F3, which is the minimum suitability of the condition part. After that, in the same way as creating the membership function 81 (y), the membership function of the control action UM is extracted, and the fitness is 0.7.
The number of membership countries of intermediate conclusion C1 with the upper part cut off is 82 (y).

E, the membership functions B (y) of all the intermediate conclusions C1 obtained are synthesized, and the composite membership function Be
Create (V). FIG. 6 shows two membership functions 81 (y) exemplified by pl.

An example of synthesis of B2(y) is shown. As shown in the figure, the membership function 81 (y) is set so that the degree of suitability is maximized for the control action level y.

B2 (y) is synthesized.

Then, the y-coordinate ally'' of the position of the center of gravity G of the region surrounded by the composite membership function BB(y) and the y-axis (indicated by diagonal lines in FIG. 6) is determined by the following equation (2).

This y indicates the necessity of control action at the time of tapping A2 obtained by fuzzy inference (steps D, to F). In other words, the closer y8 is to 1, the more it is determined that there is a need for a heating action, the closer yl is to -1, the more necessary a cooling action is determined to be, and if yl is near O, the control action is determined to be necessary. It was determined that there was no need.

G. Flow of Blast Furnace Evaluation Method FIG. 7 is a flowchart showing the process flow of the blast furnace furnace heat evaluation method, which is an embodiment of the present invention.

The flow will be explained below with reference to the same figure.

First, in step S1, the converted hot metal temperature V'(t), which is obtained by removing the influence of operational actions, is obtained from the actual hot metal wetness V(t) using equation (1) as described in the N section.

Next, in step S2, as mentioned above, from the converted hot metal temperature V' (t), the past three hot metal temperature representative values T - T
Calculate 3.

Next, in step S3, as described in Ω4, the furnace heat evaluation points F1 to F3 are obtained from the hot metal temperature representative values T1 to T3 using the membership function.

Then, as described in step S4, the furnace heat evaluation points F1 to F3 are checked against the furnace heat evaluation rule, and the intermediate conclusion C1 is
and the membership function B (y
).

Thereafter, in step S5, as described in Ω4, the membership functions B (y) of the intermediate conclusion C1 are synthesized to create a composite membership function Be (y).

Then, in step S6, as described in Ω4, the y-coordinate y* of the center of gravity of the region surrounded by the composite membership function BB (V) and the y-axis, that is, the necessity of the control action at A2 during tapping, is obtained. .

Ratio-1 Naoshige Momou 1 As described above, according to the blast furnace furnace heat evaluation method according to this embodiment, furnace heat evaluation can be performed using the representative values of the past three tapping temperatures, so furnace heat evaluation can be performed in a short time. .

Furthermore, since the furnace heat level is determined using the membership function, quantitative evaluation of the furnace heat level can be performed.

Further, by fuzzy reasoning using the furnace heat rules shown in Table 1, it is possible to accurately grasp the necessity of control actions at a specific time of tapping in the past.

Furthermore, the typical value of hot metal temperature is the converted hot metal temperature y'(t), which removes the influence of operational actions, and the value of the converted hot metal temperature y'(t) is calculated from Since thermal evaluation can be performed, accurate furnace heat evaluation can be performed at all times.

The value of the action necessity y1 at the time of tapping A2 obtained from the flow shown in the rainbow, and the furnace heat operation guide such as prediction of furnace heat drop at the time of tapping A2, or the operation instruction m of the blast furnace operation system at the time of tapping A2 The accuracy of the furnace heat operation guide and blast furnace operation system can be determined by comparing the values.

In this example, the furnace heat was evaluated based on the representative values of the hot metal temperatures measured three times in the past, but the present invention is not limited to this.

Further, in this embodiment, the necessity of the v control action at the time of tapping A2 was evaluated, but the present invention is not limited to this.

(Effect of the invention) As explained above, according to this invention, it is possible to
Since the furnace heat evaluation is performed based on the n hot metal temperature representative values during the relatively small number of times of tapping, the furnace heat evaluation can be performed in a relatively short period of time.

Further, in the second step, the furnace heat level for each of the n hot metal temperature representative values is determined by the membership function, so that the furnace heat level can be determined in a constant manner.

Furthermore, from the rules predetermined in the third step and the furnace heat level, m (m<n
) Since the necessity of the control action at the previous time of tapping is determined, the necessity of the control action at the time of specific tapping in the past can be accurately grasped.

In addition, the representative value of hot metal temperature is calculated based on the converted hot metal temperature obtained by removing the influence of heat raising and cooling actions from the actual melting degree, so it is Furnace heat evaluation can always be performed with high accuracy.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the state of heating action erosion, Fig. 2 is an explanatory diagram showing the change over time of converted hot metal temperature y'(t), Figs. 3 and 4 are graphs showing membership functions,
Figure 5 shows the membership function B (y) of intermediate conclusion C1.
FIG. 4 is a graph showing a method for creating the composite membership function 88 (V). FIG. 7 is a flowchart showing the process flow of a blast furnace furnace heat evaluation method which is an embodiment of the present invention. , FIG. 8 is a flowchart showing the process flow of a conventional blast furnace furnace heat evaluation method. V(t)...Hot metal m degree, y'(t)...Converted hot metal temperature, Z(t)...Actual action change predicted value, B(V)・
...Membership function of intermediate conclusion, BB (V)...
・Composite membership function Figure 1

Claims (1)

[Claims] (1) A first step of calculating the converted hot metal temperature by removing the influence of heat raising action and heat lowering action from the actual hot metal temperature, and calculating n in the past n times of tapping based on the converted hot metal temperature.
a second step of determining the n representative hot metal temperature values; a third step of determining the furnace heat level for each of the n hot metal temperature representative values using a membership function; and a predetermined rule and the furnace heat level. and a fourth step of determining the necessity of a control action at the time of tapping m (m<n) times before by fuzzy inference.