JPH0610057A - Method and device for controlling temperature of strip material in heating furnace - Google Patents

Abstract

PURPOSE:To enable the control of plural heating furnaces with a single control part at the same time by calculating a typical fuel flow rate and an individual fuel flow rate based on a typical furnace temp. calculated from each furnace temp. of plural heating furnace arranged in series. CONSTITUTION:The temp. of the steel strip passing through plural heatiang furnaces A, B arranged in series along a conveying course is controlled by controlling the fuel flow rate. Then, from the actual value of the furnace temps. Fa. Fb in each of the heating furnaces A, B, the typical furnace temp. F in an apparent single typical furnace R including these furnaces is calculated in a typical furnace temp. calculating part CF. The typical furnace temp. F together with the strip temp. T in the strip temp. meter TB are inputted into an optimum strip temp. control part C. At this time, based on the production information I containing the aimed strip temp. T0, the typical fuel flow rate Q of the typical furnace R is calculated. Based on the setting value Q, the individual fuel flow rates Qa, Qb in each of the heating furnaces A, B are calculated in an individual flow rate calculating part CQ. Based on these setting values Qa, Qb, the heating furnaces A, B are controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating furnace plate temperature control method and apparatus for a plate-like body used for annealing a steel plate or a thin steel strip.

[0002]

2. Description of the Related Art A steel sheet after cold rolling is continuously passed through a heating furnace, a soaking furnace or a cooling furnace arranged in series by using a transfer mechanism and annealed to improve quality such as strength. A continuous annealing treatment facility is installed. In such a continuous annealing treatment facility, in order to ensure the quality of the steel sheet after treatment and avoid operating troubles such as heat buckles, it is important to control the temperature of the steel sheet, which is called "sheet temperature". Plate temperature control in a heating furnace has become an important issue.

In the continuous annealing treatment equipment, different kinds of steel plates having different widths such as "plate width" and "plate thickness" are joined together by using an automatic welding mechanism. A method called "replacement of set" is adopted. At the joint between different steel plates that appears with such a set change, the plate width, which is a parameter for the heating furnace plate temperature control,
Under the situation that the plate thickness changes stepwise and the conveying speed of the steel plate, which is called "passing speed", reaches several tens to several hundreds of meters per minute, the control is considerably advanced. Will be required.

The plate temperature control in the heating furnace is "exit plate temperature"
The plate temperature at the outlet of the heating furnace, which is referred to as the control furnace, is used as the control amount, and the flow rate of fuel such as coke gas to be supplied to the heating furnace or the furnace temperature to be set in the heating furnace is used as the manipulated variable. When the furnace temperature is used as the operation amount in the upper control unit, a lower control unit called an instrumentation controller is installed between the upper control unit and the heating furnace, and the lower control unit is installed. As a result, the furnace temperature, which should be called the upper manipulated variable, is converted into the fuel flow rate, which is also called the lower manipulated variable.

Generally, in a heating furnace, in order to realize a predetermined annealing cycle of a steel sheet, facilitate control, save fuel consumption, etc., the heating furnace is divided into a plurality of parts along the conveying path of the steel sheet and arranged in series. Alternatively, a method of dividing the inside of the heating furnace into a plurality of zones (“heating zones”) arranged in cascade is adopted. The heating zone is functionally similar to the heating furnace in that the fuel flow rate and temperature can be controlled almost independently of other heating zones. Therefore, hereinafter, the heating furnace is collectively referred to as the heating furnace.

FIG. 4 exemplifies a conventional typical system configuration in which two heating furnaces A and B are arranged in a row along the sheet conveying path. The optimum plate temperature control unit CA measures actual values Fa and T called “actual values” with respect to the furnace temperature and the plate temperature.
a is received from each of the heating furnace A and the plate thermometer TA, and the target plate temperature Tao, the plate width, the plate thickness associated with the set change, etc.
It receives parameters such as the strip running speed as the production information IA, calculates the fuel flow rate Qa according to a predetermined algorithm, and outputs it to the heating furnace A as a “set value”. Similarly, the optimum plate temperature control unit CB also receives the actual values of the furnace temperature Fb and the plate temperature Tb from each of the heating furnace B and the plate thermometer TB, receives the production information IB, and determines the fuel flow rate Qb according to a predetermined algorithm. Calculate and output to heating furnace B as a set value.

The optimum plate temperature control units CA and CB take in the "plate temperature model" for predicting the outlet plate temperature from the production information and the operation results, and the actual values of the plate temperature and the furnace temperature, and obtain the actual values of the plate temperature. It is configured to perform closed-loop control so as to approach the target plate temperature trajectory calculated using the plate temperature model. For the details of the optimum plate temperature control using this plate temperature model, Japanese Patent Application No. 60-28408 entitled "Method and apparatus for controlling plate temperature in continuous annealing furnace" related to the applicant's prior application, if necessary. (Japanese Patent Application Laid-Open No. 61-190026) and "Measurement and Control" Vol. 25, No. 11 (November 1986)
"Continuous annealing treatment equipment (C.A.P.L.)"
See Yoshiya's paper entitled "Optimal Plate Temperature Control Method for Heating Furnace".

[0008]

In the conventional heating furnace plate temperature control device shown in FIG. 4, two thermometers for measuring the furnace temperatures of two heating furnaces and the outlets of the heating furnaces are provided. Two thermometers are used to measure the plate temperature. As the two furnace thermometers, thermocouples and other highly accurate and reliable ones can be used, but as the plate thermometer, the non-contact type radiation thermometer is used because the steel plate to be measured is transported while corrugating. I have no choice but to rely on. Since such a radiation thermometer is still not sufficient in terms of reliability depending on the surrounding environmental conditions, it may not be possible to measure the plate temperature with high accuracy in a furnace with poor environmental conditions, which may lead to abnormal control. There is a problem with.

Further, in the conventional control configuration shown in FIG. 4, an optimum plate temperature control section is required for each heating furnace. These two optimum plate temperature control units are actually realized by a common control program executed on a computer in a time-shelling manner. However, such a computer normally controls the transfer mechanism and the automatic welding mechanism. In many cases, a wide variety of processes in the continuous annealing system including the control of, the system system screen display, etc. are simultaneously executed. Therefore, as the computer load including the two optimum plate temperature controls increases, an expensive computer having a higher processing capacity and a large number of computers are required, and the founding cost and running cost of the entire continuous annealing system increase. There is also a problem.

[0010]

The heating furnace plate temperature control method of the present invention for solving the above problems is a process for measuring the furnace temperature of each heating furnace and the plate temperature carried out from the final stage heating furnace. When,
Process to calculate the representative furnace temperature based on the measured furnace temperature of each heating furnace, and calculate the representative operation amount based on the calculated representative furnace temperature, production information including the target value of the plate temperature, and the measured value of the plate temperature The process includes a process and a process of calculating an individual operation amount for each heating furnace based on the representative operation amount.

According to the heating furnace plate temperature control method of the present invention, the plate thermometer, which is problematic in terms of reliability and price, is omitted in the heating furnace in the preceding stage. At the same time, a plurality of units, for example, two units arranged in series by an apparently single “representative furnace” having a single actual value called “representative furnace temperature” and a single operation amount called “representative operation amount” By simulating the heating furnace of the stand, the existing optimum plate temperature control processing is unified without any change. In order to achieve this, the process of calculating a single representative furnace temperature from the actual value of the furnace temperature that actually exists for each heating furnace, and conversely Processing for calculating the required individual operation amount is added for each. Each calculation process is very simple in many cases because the calculation formula does not include a variable of time as exemplified in the following examples. As the optimum plate temperature control processing, existing ones disclosed in the above patent documents and academic papers,
Improved versions of these can be used. With such a configuration, it is possible to simultaneously control a plurality of furnaces including a furnace that cannot measure the plate temperature with high accuracy, and further, the computer load can be significantly reduced by unifying the optimum plate temperature control processing.

[0012]

FIG. 1 shows the structure of a heating furnace plate temperature control apparatus to which a heating furnace plate temperature control method according to an embodiment of the present invention is applied, in which a steel plate to be controlled and two units arranged in series for heating the steel plate are controlled. It is a functional block diagram shown with the heating furnace of FIG. A heating furnace A at the front stage and a heating furnace B at the rear stage are arranged in series along a conveyance path of a steel sheet conveyed at an appropriate plate passing speed by an appropriate conveyance mechanism (not shown). The representative furnace temperature calculation unit CF calculates the representative furnace temperature F based on the furnace temperatures Fa and Fb measured in the heating furnaces A and B.
Is calculated and output to the optimum plate temperature control unit C. The optimum plate temperature control unit C, based on the representative furnace temperature F and the actual plate temperature value T at the outlet of the subsequent heating furnace B output from the plate thermometer TB, and the production information I including the target plate temperature To, Representative fuel flow rate Q to be set in order to bring the actual plate temperature value T close to the target plate temperature To
Is calculated and output to the individual flow rate calculation unit CQ. The individual flow rate calculation unit CQ calculates the fuel flow rates Qa and Qb set for the heating furnaces A and B based on the representative furnace temperature F output from the optimum plate temperature control unit C and the production information, and the respective heating furnaces. Output to.

In this way, in practice, two heating furnaces A and B are used.
However, the actual value of the furnace temperature input to the single optimum plate temperature control unit C is the single representative furnace temperature F, and the actual value of the plate temperature is the latter heating furnace B. Is the actual value T from the plate temperature gauge TB installed at the outlet of the, and the operation amount output as a set value from the optimum plate temperature control unit C is only a single representative fuel flow rate Q. Therefore, when viewed from the optimum plate temperature control unit C, the situation is similar to the case where there is an apparently single heating furnace R surrounded by a dotted line in FIG. In this specification, such an apparently unified heating furnace is referred to as a “representative furnace”. As a result, the function of the unified optimum plate temperature control unit C becomes exactly the same as the optimum plate temperature follow-up control units CA and CB required for each heating furnace shown in FIG. 4, and the existing function ( Actually, the existing optimum plate temperature control units CA and CB shown in FIG. 4 can be used as they are without changing the control program executed by the computer.

As described above, in order to enable the unification of the controlled objects by the representative furnace, the actual representative values Fa and Fb of the furnace temperature existing for each heating furnace are actually used to represent the single representative furnace temperature F. The representative furnace temperature calculation unit CF for creating the fuel flow rate and, conversely, the individual representative fuel flow rate Q for individually creating two fuel flow rates Qa and Qb required for each heating furnace. A flow rate calculation unit CQ is provided. With such a configuration, it is possible to omit one plate thermometer having a problem in terms of reliability and cost without making any complicated changes to the existing optimum plate temperature control unit. Further, by unifying the optimum plate temperature control unit realized as a computer program, the load on the computer can be significantly reduced.

The representative furnace temperature calculation unit CF of FIG. 1 calculates the representative furnace temperature F by weighting the furnace temperature Fa and the furnace temperature Fb output from each heating furnace, as shown in FIG. 2, for example. It is composed. However, the weighting coefficient k is a constant of 0 or more and 1 or less. This weighting coefficient k is set in consideration of empirical values based on the furnace temperature target value of each heating furnace, the calorific value, the heat capacity, the thermal time constant, etc., and can be easily changed according to the results of subsequent operations. It has become.

For example, as shown in FIG. 3, the individual flow rate calculation unit CQ of FIG. 1 has no relation to the representative fuel flow rate Q calculated by the optimum plate temperature control unit C, and only the production information I indicates the fuel of the heating furnace B. The flow rate Qb calculation unit calculates the flow rate Qb, and the flow rate Qa calculation unit calculates the fuel flow rate Qa by subtracting the fuel flow rate Qb calculated here from the representative fuel flow rate Q. The flow rate Qb calculation unit refers to a conversion table created on the basis of various parameters included in the production information I, for example, a target plate temperature, a plate width, a plate thickness, a plate passing speed, etc. The fuel flow rate Qb to be set in the furnace B is calculated and output.

In FIGS. 2 and 3, the functions of the representative furnace temperature calculation unit CF and the individual flow rate calculation unit CQ are illustrated by a hardware configuration for convenience of explanation, but the function of each calculation unit is the optimum optimum plate temperature. The control unit C may be realized by software running on a computer, and the increase amount of the computer load in this case is negligible considering the simplicity of the content of the calculation algorithm.

As described above, the individual fuel calculating section CQ illustrated in FIG.
In the above, the configuration is shown in which the fuel flow rate Qb set in the heating furnace B in the subsequent stage is calculated from only the production information regardless of the representative fuel flow rate Q, and the remaining portion is assigned to the heating furnace A in the preceding stage. However, conversely, the fuel flow rate Qa set in the heating furnace A in the former stage may be calculated from only the production information regardless of the representative fuel flow rate Q, and the remaining portion may be allocated to the heating furnace B in the latter stage. it can.

Alternatively, a distribution ratio may be set for each heating furnace to calculate the fuel flow rate Qa, Qb of each heating furnace. Furthermore, the actual values Fa and Fb of the furnace temperature A and the furnace temperature B are input to the individual flow rate calculation unit CQ, and the fuel flow rates Qa and Qb to be distributed to each heating furnace are calculated based on these actual values and production information. It can also be configured.

Further, the present invention has been described by taking as an example the case of controlling two heating furnaces arranged in series along the conveyance path of the steel sheet. However, in general, the present invention can be applied to the case of controlling three, four, ... Heating furnaces that are connected in series along the steel sheet transport path. In this case, a plate thermometer is installed only at the exit of the heating furnace at the final stage, and 3 units, 4 units ...
The heating furnace is simulated as a representative furnace.

[0021]

As described in detail above, the heating furnace plate temperature control method and apparatus of the present invention comprises the concepts of representative furnace temperature and representative manipulated variable, and representative furnace temperature calculating means and individual flow rate calculating means. This makes it possible to control multiple furnaces at the same time, including multiple furnaces that appear to be simulated by a single representative furnace. A great reduction in the computer load due to the unification of processing is achieved. In addition, the introduction of this representative furnace has an advantage that the existing optimum plate temperature control process can be used as it is.

Further, since the representative furnace temperature calculation process and the individual flow rate calculation process have an upper and lower hierarchical structure with respect to the optimum plate temperature control process, respective functions can be independently developed or improved. Therefore, there is an advantage that the labor required for developing and improving the control program for realizing each function is significantly reduced and the time required for the development is also significantly reduced.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing a configuration of a heating furnace plate temperature control apparatus to which a heating furnace plate temperature control method according to an embodiment of the present invention is applied, together with a steel plate to be controlled and two heating furnaces arranged in cascade. .

FIG. 2 is a functional block diagram showing an example of a configuration of a representative furnace temperature calculation unit CF of FIG.

3 is a functional block diagram showing an example of a configuration of an individual flow rate calculation unit CQ of FIG.

FIG. 4 is a functional block diagram showing a configuration of a conventional heating furnace plate temperature control device together with a steel plate to be controlled and two heating furnaces arranged in cascade.

[Explanation of symbols]

A, B Two heating furnaces arranged in series TB Plate thermometer C Optimal plate temperature control unit (means) CF Representative furnace temperature calculation unit (means) CQ Individual flow rate calculation unit (an example of individual manipulated variable calculation means) R Representative Reactor F Representative furnace temperature Fa, Fb Actual value of furnace temperature of heating furnaces A and B Q Representative fuel flow rate (an example of typical operation amount) Qa, Qb Fuel flow rate set in heating furnaces A and B

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shozo Kato 2-3-6 Otemachi, Chiyoda-ku, Tokyo Within Nippon Steel Corporation (72) Innovator Naoji Yoshiya 2--6, Otemachi, Chiyoda-ku, Tokyo No. 3 In Nippon Steel Co., Ltd. (72) Inventor Masashi Kaji 3-2-1 Hanzen Minamishinmachi, Amagasaki City, Hyogo Prefecture Daido Steel Plate Co., Ltd. No. 1 Daido Steel Sheet Co., Ltd.

Claims (6)

[Claims] 1. A temperature of a plate-shaped body heated by each heating furnace is controlled by controlling a plurality of heating furnaces (including heating zones) arranged in series along a conveyance path of the plate-shaped body. And a process for measuring the temperature of the plate-like body carried out from the heating furnace of each heating furnace and the heating furnace at the final stage (referred to as “plate temperature”), and each of the measured temperatures. Optimal to calculate the representative furnace temperature based on the furnace temperature of the heating furnace, and to calculate the representative operation amount based on the calculated representative furnace temperature, production information including the target value of the plate temperature, and the measured value of the plate temperature. A heating furnace plate temperature control method for a plate-shaped body, comprising: a plate temperature control process; and a process of calculating an individual operation amount for each heating furnace based on the calculated representative operation amount. 2. A temperature of a plate-shaped body heated by each heating furnace is controlled by controlling a plurality of heating furnaces (including heating zones) arranged in series along a conveyance path of the plate-shaped body. And a measuring unit for measuring the temperature of each of the heating furnaces and the temperature of the plate-shaped body carried out from the heating furnace at the final stage (referred to as “plate temperature”); Representative furnace temperature calculation means for calculating the representative furnace temperature based on the furnace temperature of each heating furnace, representative operation based on the calculated representative furnace temperature, production information including the target value of the plate temperature, and the measured value of the plate temperature A heating furnace plate temperature for a plate-shaped body, comprising: an optimum plate temperature control means for calculating the amount; and an individual operation amount calculating means for calculating an individual operation amount for each heating furnace based on the representative operation amount. Control device. 3. The plate-shaped body according to claim 2, wherein the representative furnace temperature calculating means calculates the representative furnace temperature by performing a weighted average of the measured furnace temperatures of the heating furnaces. Heating furnace plate temperature control device. 4. The heating furnace plate of a plate-like body according to claim 2 or 3, wherein the representative manipulated variable calculated by the optimum plate temperature control means is a sum of fuel flow rates to be supplied to each heating furnace. Temperature control device. 5. The set operation amount calculating means according to claim 4, wherein the set operation amount calculation means calculates an individual fuel flow rate for a part of the heating furnaces based on the production information, and the set individual fuel flow rate is set as the A heating furnace plate temperature control device for a plate-shaped body, wherein the individual fuel flow rate for the remaining one of the heating furnaces is calculated by subtracting from the sum of the fuel flow rates calculated by the optimum plate temperature control means. 6. The heating furnace plate temperature control device for a plate-shaped body according to claim 5, wherein a part of the heating furnace includes a final stage heating furnace.