JPH09310114A - Method for adjusting component in ladle refining furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a component adjustment means in a ladle refining furnace, by which the component adjustment can accurately and quickly be executed even by an operator who does not have much experience. SOLUTION: An expert system is used to execute the decision of the element needing the adjustment and the setting of the target value of the decided element from target ranges (the upper limit value, the lower limit value and the final target value) of molten steel components, the analyzed values of the molten steel components, slag thickness, adjusting stages (initial stage, middle stage and end stage), molten steel wt. and alloy component values. Further, the alloy required to adjust the element and the alloy adding quantity are obtd. By this method, the ladle refining time is shortened.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for adjusting the composition of molten steel in a ladle refining furnace.

[0002]

2. Description of the Related Art Conventionally, when adjusting components in a ladle refining furnace, an operator first collects a sample of molten steel and examines the component value of the sample with a molten steel component analyzer. When the analysis result of the composition is known, the target range of the composition of the molten steel, the analysis result of the composition and the state of the molten steel are used to determine the target value of the composition, and the amount of addition of the alloy required to reach the target value is determined.

However, in the case of this method, in order to determine the target value of the molten steel component, a lot of knowledge and experience such as understanding of the mass transfer phenomenon between the molten steel and the slag, selection of alloy and grasping of the molten steel state are required. However, the number of workers who can adjust the components is limited to a small number of people, it is not versatile, and it is inefficient because it requires a lot of labor and time, and further it is easy to make calculation errors, so it is necessary to adjust the components. There were problems such as making mistakes.

Therefore, in view of these problems, for example, in Japanese Patent Laid-Open No. 2-274806, based on the Si analysis value and the amount of slag in the ladle, the component value of each alloy is
Correction is performed by subtracting the amount of Si absorbed in the slag and adding the amounts of Mn and Cr returned to the molten steel, and calculating the added amount of each alloy using the corrected alloy component values. A method for improving the accuracy of is proposed.

That is, in this alloy addition amount calculation method, in the alloy components added to the molten steel, the component value obtained by subtracting the absorption amount corresponding to the absorption amount of Si that tends to be absorbed from the molten steel to the slag is calculated from the slag to the molten steel. Mn and C tending to return
For r, the component value to which the return amount is added is used,
Furthermore, it is a method of calculating the addition amount after correcting the alloy component value with the slag amount related to the absorption amount and the return amount, and it is possible to accurately approximate the molten steel component after component adjustment to the component target value. It is excellent in that it exists.

However, the correction of the component values of each alloy in this method is to correct the amount of Si in the molten steel, Si, Mn, and Cr.
Of the amount of Si, Mn, and Cr in each alloy by using a relational expression in which the relation between the amount of molten steel slag and the amount of movement and the amount of slag are tabulated or mathematically expressed by actual measurement data. Since it is necessary to make a correction to increase or decrease
There is a problem that it takes time to calculate the amount of alloy addition required for component adjustment, lacks swiftness, and the refining time cannot be shortened.

[0007]

The present invention solves all the problems of the prior art described above, so that even an operator who does not have much experience can adjust the components accurately and quickly. It is intended to propose a component adjustment method that can shorten the refining time of the pot refining furnace.

[0008]

SUMMARY OF THE INVENTION The present invention is a rule-based expert that rules out the experience of a skilled person in the case of calculating the amount of alloy addition necessary for adjusting the composition of molten steel in a ladle refining furnace. Using the system,
This is a method of accurately determining the target value of molten steel and determining the required amount of alloy addition. The main points are the target range of molten steel components (upper limit value, lower limit value, final target value), analysis value of molten steel component, slag. From the thickness, adjustment stage (initial stage, middle stage, end stage), molten steel weight and alloy component values, an expert system is used to determine the element that requires adjustment and set the target value of the determined element. It is characterized in that an alloy necessary for adjusting the element and the amount of the alloy added are determined.

The expert system used in the present invention will be briefly described. The expert system is a so-called computer system, and in general, it is inferred from a knowledge base created by an expert.
An expert system developed to create a schedule for a steelmaking process consisting of a plurality of unit processes is known as a system that professionally solves a problem in a specific field or application area, and is one that utilizes this ( Japanese Patent Laid-Open No. 4-2
79968). This expert system stores operation data that defines the equipment of the steelmaking process and the raw materials supplied to it, and the rules for resolving the conflict of these raw materials when multiple raw materials compete for a certain unit process. The knowledge base and the contents of the current operation data are examined, a rule matching the operation data is searched from the knowledge base, and if there is a matching rule, the content of the operation data is updated according to the instruction of the matching rule. It is equipped with an engine, and compared with the method of mathematically modeling the steelmaking process and solving this mathematical model,
It has been widely used in recent years in that it has excellent maintainability of programs (rules) and that the time required for creating an operation schedule can be set to a length that can be practically used.

The present invention focuses on the expert system having the above-mentioned advantages, and if this expert system is used as a component adjusting method in ladle refining, the amount of alloy addition necessary for adjusting the composition of molten steel is calculated. In some cases, by converting the experience of experts to rule-based
The inventors have found that the target value of molten steel can be determined quickly and accurately without requiring much experience, and that the required additive amount of alloy can be obtained, and have found the present invention. .

The target range (upper limit value, lower limit value, final target value) of the molten steel component in the present invention is set for the element to be adjusted and the element for each type of molten steel manufactured in the ladle refining furnace. .

In the ladle refining furnace, necessary auxiliary materials such as alloys are added based on the results of composition analysis of molten steel, but at that time, adjustments are made once due to disturbances such as return from slag and operational fluctuations. First, the auxiliary raw material such as alloy is added in three times.
This is called the adjustment stage and can be divided into the initial stage, the middle stage, and the final stage.

In the present invention, the determination of the element that requires adjustment, that is, the element that needs to be added with the alloy, is determined by the expert system from the molten steel component analysis value and the target range of each element. That is, all the elements set in the target range are searched by the inference engine for elements that meet the rules created in advance, and the elements to be adjusted are determined. Further, the target value of the element determined by this judgment is set by selecting one that complies with the element-specific rule created in advance.

When the element to be adjusted is determined, the alloy for adjusting the element is determined from the alloys containing the element as the main component according to the preset priority order. When the alloy is determined, the necessary addition amount is calculated from the molten steel weight, the main component value of the alloy, and the current value so that the element becomes the target value.

[0015]

1 is a schematic view showing an example of the construction of an apparatus for carrying out the method of the present invention, FIG. 2 is a block diagram showing a ladle refining furnace computer in the same apparatus, and FIG. 3 is the same apparatus. It is a flowchart which shows the component adjustment method of a ladle refining furnace, 1 is a ladle refining furnace, 1-1 is a ladle, 1-
2 is a furnace lid, 1-3 is a three-phase AC electrode, 1-4 is an argon inlet, 2 is molten steel, 3 is slag, 4 is an alloy charging device, 5 is a molten steel component analysis value input device, 6 is a molten steel amount input Device, 7 is a slag thickness input device, 8 is a ladle refining furnace computer, 8-
1 is a molten steel component analysis value processing unit, 8-2 is an information processing unit, 8-
3 is an expert system processing unit, and 8-4 is an equipment signal processing unit.

In the ladle refining furnace 1, an auxiliary material such as an alloy is added to adjust the composition so that all the elements of molten steel melted in an electric furnace or the like fall within a set target range. At that time, the temperature of the molten steel can be raised by the three-phase AC electrodes 1-3 or the like.

The molten steel component analysis value input device 5 is for inputting the component analysis values of each element of the molten steel 2 into the ladle refining furnace computer 8, and the molten steel amount input device 6 is for ladle weight of the molten steel 2. It is for inputting into the refining furnace computer 8.

The ladle refining furnace computer 8 includes a molten steel component analysis value processing unit 8-1, an information processing unit 8-2, an expert system processing unit 8-3 and an equipment signal processing unit 8-4. The analysis value processing unit 8-1 has a function of sending the analysis value input from the molten steel component analysis value input device 5 to the information processing unit 8-2, and the information processing unit 8-2 displays the data on the screen and performs other processing. This is a part that processes data from the department, receives input data from workers, etc. Specifically, it manages the target range of components for each material, calculates the slag thickness and molten steel weight, etc. The component adjustment can be performed by. The expert system processing unit 8-3 activates the expert system based on the data received from the information processing unit 8-2 and transmits the output result to the information processing unit 8-2 again. The equipment signal processing unit 8-4 is a portion for inputting / outputting equipment signals of the ladle refining furnace 1, so that the addition results of alloys and the like can be collected and the operation of the equipment (gas flow rate etc.) can be set. Has become.

Next, the procedure for adjusting the components of the present invention by the above apparatus will be described. First, input data required to carry out the present invention is prepared. That is, prepare the target range of molten steel components (upper limit value, lower limit value, final target value), analysis value of molten steel component, slag thickness, adjustment stage (initial stage, middle stage, end stage), molten steel weight and alloy component value. (Step 3 in FIG. 3).

This input data is input to the ladle refining furnace computer 8 by each input device, and from the analysis value input from the molten steel component analysis value input device 5 and the target range of each element, the expert system processing unit In 8-3, the element to be adjusted, that is, the element to which the alloy needs to be added is determined. Specifically, all the elements set in the target range are searched by the inference engine for elements that meet the rules shown in Table 1 created in advance, and the elements to be adjusted are determined (step in FIG. 3).

Next, target values are set for all the elements determined to require adjustment (step in FIG. 3). The target value of each element is set by searching for those that meet the conditions of the element-specific rules shown in Tables 3 and 4 created in advance. However, depending on the conditions, it may be determined that the adjustment is not performed at this stage.

Elements requiring adjustment are classified as shown in Table 2 and the priority order for adjustment is determined (step in FIG. 3). In this case, the order does not matter within the same group.

When the element to be adjusted is determined, according to a preset priority order among alloys containing the element as a main component,
The alloy for adjusting the element is determined (FIG. 3 step). The priority of alloys is basically decided by considering the cost, but it may be changed depending on the stock situation.

When the element to be adjusted and the alloy necessary for adjusting the element are determined, it is necessary by the following formula (1) from the molten steel weight, the main component value, the target value and the current value so that the element becomes the target value. The addition amount is calculated (step in FIG. 3).

Addition amount = (target value-current value) / (main component value of target alloy-target value) × (molten steel weight) Equation (1)

Once the required addition amount of the alloy is determined by the formula (1), changes in other elements when the alloy is added are examined. Specifically, for the elements contained in the alloy, the component value after addition is determined by the following formula (2). For elements not contained in the alloy, the value after addition is determined by the formula (3) (step in FIG. 3).

Component value after addition = {(current value) × molten steel weight + (alloy component value) × (addition amount)} / (molten steel weight + alloy addition amount) Equation (2)

Component value after addition = (current value) × (molten steel weight) / (molten steel weight + amount of alloy added) Equation (3)

When the component values after addition are obtained by the equations (2) and (3), it is checked whether or not the target range is exceeded for all the elements. That is, there are no adjustment plans for the (a) component that exceed the upper limit, or there are no adjustment plans for the (a) component that exceed the target component value at the final stage, (C) Check if there are any components that are scheduled to be adjusted that exceed the target value,
If there is any one of (a) to (c), change the alloy with the highest addition amount among the alloys that have been added so far and adjust with the alloy of the next priority (Fig. 3). Step,).

By calculating for all the elements to be adjusted by the above procedure, the alloy to be added and the amount to be added can be determined for the component adjustment of the ladle refining furnace.

The output result of the expert system processing unit 8-3 is passed through the information processing unit 8-2 and the equipment signal processing unit 8
-4, and the components in the ladle refining furnace 1 are adjusted based on the contents.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

[0035]

[Table 4]

[0036]

As described above, according to the method of the present invention, an expert system based on a rule base in which the experience of a skilled person is made into a rule when adjusting the components is used to select the element to be adjusted and its target value. Since it is possible to obtain the appropriate value and the type of alloy required to reach the target value and the amount added, it is possible for even an inexperienced worker to adjust the composition accurately and quickly. , It has an excellent effect that the refining time of the ladle refining furnace can be shortened.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of the configuration of an apparatus for carrying out the method of the present invention.

FIG. 2 is a block diagram showing a computer for a ladle refining furnace in the above apparatus.

FIG. 3 is a flowchart showing a component adjusting method of a ladle refining furnace by the same apparatus.

[Explanation of symbols]

 1 Ladle refining furnace 1-1 Ladle 1-2 Furnace cover 1-3 Three-phase AC electrode 1-4 Argon injection port 2 Molten steel 3 Slag 4 Alloy injection device 5 Molten steel composition analysis value input device 6 Molten steel amount input device 7 Slag Thickness input device 8 Computer for ladle refining furnace 8-1 Molten steel component analysis value processing unit 8-2 Information processing unit 8-3 Expert system processing unit 8-4 Equipment signal processing unit

Claims (1)

[Claims] 1. A method for adjusting the composition of molten steel in a ladle refining furnace, wherein a target range of molten steel composition (upper limit value, lower limit value, final target value), analysis value of molten steel composition, slag thickness, adjustment stage (initial stage, middle stage) (Stage, end stage), based on the weight of molten steel and the component value of the alloy, an expert system is used to determine the element that requires adjustment, set the target value of the determined element, and adjust the element. Alloy and a method for adjusting the composition in a ladle refining furnace, characterized in that the addition amount of the alloy is determined.