JPS62263516A - Temperature control method and instrument for heating furnace - Google Patents

Abstract

PURPOSE:To control a furnace temperature with an optimum response even when the heat load of a heating furnace is drastically changed by changing the control gain of a PID controller based upon a heat load changing quantity. CONSTITUTION:After the change of a control gain Y accompanying the change of the heating conditions of a heated material 10 inserted into a heating furnace 12 is processed by an optimum gain arithmetic unit 30, a change command S is generated. A reading command R is inputted through a line 46 to a PID controller 18 based upon the change command S. Based upon the reading command R inputted, the PID controller 18 reads the new control constant of control gains KP, KI and KD corresponding to respective control actions of P (proportion), I (integrating) and D (differential) through lines 48, 50 and 52, and by executing the re-setting, the constant is changed automatically. Even when the heat load in the furnace s changed, the control gain of the PID controller can be changed corresponding to the change, and therefore, the response of a furnace temperature control will not be reduced.

Description

[Detailed description of the invention]

(Industrial Field of Application 1) The present invention relates to a heating furnace temperature i11 control method and equipment, and particularly relates to a furnace (heating furnace, heat treatment furnace, etc.) that heats steel materials, slabs, billets, fine pipes, steel plates, etc. ) (I) I D
The present invention relates to an improvement in a heating furnace temperature control method and device controlled using a controller. [Prior Art] Generally, in a furnace for heating steel materials, the exhaustion inside the furnace is normally controlled by feedback control 21 using a PID controller.
) is restricted by 11. In addition, this PID
``I 'fR meter, P (proportional) I (fa > D <
All 1. The general term is used not only to refer to all the controllers that have been used, but also to include controllers that have only one (or two) function, such as P, PI, PD, etc. Figure 3 shows an example of temperature control for a heating furnace described in the ``Automatic Control Handbook Equipment Application Edition'' published by Japan. Similarly, an example of the configuration of this control device is shown in Figure 4. , when the raw material 10 is heated in the heating furnace 12 to become η crystal 1/I, the temperature T in the furnace is actually measured by the temperature measuring device 16.The actual temperature T is determined as shown in FIG. ) The deviation from the temperature 112T is calculated using the following equation (1), and the temperature deviation ΔT is obtained. ΔT −T −T ・・・・・・・・・(1
) The obtained temperature deviation ΔT is input to the PID controller 18, and the prow4 node 18 performs the following formula (2) using the input temperature difference ΔT, and outputs a control signal ε. . ε(t)−KP・ΔT+K r・fΔT・(1[+KO
・(dΔT/dt) (2) where Kp is a proportional gain, Kl is an integral gain, Ko is a differential gain, and t is time. The output control signal ε is input to the combustion control device 20,
The combustion control device 20 includes a fuel control valve 22 and an intake air amount control valve 2.
4 to burn air, gas, oil, etc., until the rW ffl G difference ΔT becomes zero. (burner 26) to raise or lower the furnace temperature T. Note that the temperature measuring device 1 for measuring the temperature T in the furnace is
6, a thermal lightning pair can be used, for example. Also, the third
In the figure, 28 is a blower motor that sends air into the heating furnace 12.

[Problems to be solved by the invention]

However, the conventional heating furnace 12 as shown in FIG.
In the temperature control technology, each control gain KP1Kr, Ko in the above equation (2) is assumed to be constant, so even if the characteristics of the combustion control 211 device 20 are always constant, the heating furnace 12 temperature This has the problem that the characteristics change depending on the load condition, resulting in a change in responsiveness, which is not desirable in terms of temperature control. In particular, in order to change the temperature target 1st shift (Py,
If the temperature]-) is significantly changed, problems such as overshoot, hunting, or response delay may occur. By the way, as a technology related to the present invention, there is a method for controlling a continuous heating furnace disclosed in, for example, Japanese Patent Laid-Open No. 57-82426. This control method uses the predicted temperature of each slab in the furnace and the target temperature in order to optimize the heating of slabs, etc. ? Find the deviation from the temperature curve, take the sum of the squares of each deviation found,
This method determines the fuel flow rate of each control zone so as to minimize it. However, even in this method,
Similar to the control technology shown in FIG. 4, this system suffers from the problem of not being able to adequately cope with rapid load fluctuations.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned conventional problems, and provides a heating furnace that can control the furnace temperature with constant or optimal responsiveness even if the heat load of the heating furnace changes rapidly. The purpose of the present invention is to provide a temperature control method and a method for controlling the temperature. [Means for Solving the Problems] The present invention provides a temperature control method for a heating furnace in which the temperature of the heating furnace is controlled using a PID controller. The above objective is achieved by understanding and changing the control gain of the PID controller based on the understood thermal load fluctuation amount. The present invention also provides a temperature control device for a heating furnace that controls the temperature of the heating furnace using a P10 controller. means for detecting a heat load state, a calculation means for calculating a heat load variation of the heating furnace based on the detected heat Ω waiting state, and a predetermined response performance based on the ejected heat Q load variation skewer. 1+7 is added to the control gain of the PID controller 1), and the calculated control gain is added to the PI
The above object is also achieved by comprising means for changing the control gain of the D controller. [Function] In the present invention, when heating a material to be heated, such as a steel material, by controlling the temperature of the BN heating furnace with a PID controller, the thermal angle change of the heating furnace is adjusted, for example, to the dimension of the heated material tlA. \5 Set J2 (or meter) to the heat load state such as the shape and number of furnaces, understand the heat load fluctuation A of the furnace, and add 1;t to the understood heat load change, Each control gain Kp of the PID adjustment ni1++1 is set so that the heating furnace is in an optimal combustion state,
By changing + and Ko, the predetermined response to heat load fluctuation is 1! I try to do that. Therefore, according to the present invention,
Even if a sudden change in the heat Ω cylindrical rS occurs in the furnace, the temperature of the heating furnace can be controlled by following it with high accuracy. Next, 6 system t2D Kane K p , K r , K
o (7) The method of determination will be explained in detail using a steel pipe as an example. First, in the equation (2) above, which calculates the black control signal ε from the temperature deviation Δc in the equation (1) above, the optimal control [1 gain Kp, + , Ko is shown as follows. KP-P (T, K, t, L, H, N>
...〈3) K+-1(T, K, t
SL, 1, N)...
(/I) K-o = D (T, K, t
, L, HlN)... (5) However, T is the temperature target (
(^, 1 is the outer diameter, t is the wall thickness, shi is the length, H is the furnace time, and N is the number of furnaces, and these represent the standard cover. Suitable DD control keys K p , K + , K o in the pre-Q state are expressed by the following equations (6) to (8). Kp-P (T, ni, t, L, H, N>...(6)
K τ = [(T, K, t, 1. t(, N)... (7) Ko-D (T, to,
t, L, H, N>-(8) where K is the outer diameter, [ is the wall thickness, L is the quality, H is the time in the furnace, and N is the number of pieces in the furnace. Here, when changing from a standard state (for example, KP) to a certain state (for example, KP), the difference in each (jn) is expressed by the following equations (9) to (17). teeth,
Express it by adding a △ to the symbol (for example, ΔKp). △KP=KP-Kp ・・・・・・(9)Δ
ni + - ni + - ni + ・・・・・・ (1
0)ΔKo−Ko Ko・−・
(11)ΔT-T-T...
... (12) Δ = = −K
...... To (13) 1 = 1 -1
・・・・・・ (14)△L=
L-L...
(15)Δl-1-H-1-1... (1G)
ΔN-N N...
...〈17) Here, (6) to (8) shown earlier
The functions of P, I, and D in the equation are set to the respective variables T, t,
If it is a function that can be divided into all 1 with respect to L, t1, and N, the following equations (18) to (20) hold true. ΔKp=(c)P/cjT>・Δt+(,3P/aK)・Δto+<aP/2)t>・Heshi+(aP/c
l) L> ・△l− +(2>P/a+−1>・Δt1+<aP/
, E) N)・ΔN ...(18) Δ+=(at/c
)T)・8T-! −(c) I/aK>・Δ+ (a +, /at) −Δt+(al/
aL) ・H + (al/c)H) ・ΔH + (c> I/c5N) ・ΔN ・・・
(19〉ΔK o = ('a D 7 ; 3 T
＞ ・ Δt+(2>D/8K) ・ Δt+(aD,/at) ・ Δt +(c>D/c)L) ・ Δ1− +(aD/aH') ・ Δt1+( aD/aN
> ・ΔN... (20) Here, the above (3)
~ When formula (11) is displayed in a matrix, the following formula (21) ~
<23). In this case, n suitable control gains KP, K
Let Y be the matrix representation representing l and KO, let Y be the matrix representation representing the standard values of these control gains, and let △Y be the matrix representing the awn of quasi 1 "J" for the optimal balance of these control gains. □Similarly, each characteristic 1i0, that is, temperature target 1 shift T, outer diameter/K1 wall thickness t1 length L1 furnace time 1'', number of furnaces N
The following equations (24) to (26) are given where the matrix representing the heat load state with respect to Furthermore, (18) to (20
) to obtain the Shōei coefficient matrix from the following formula (27
)become that way. (27) The above matrix is expressed as follows from equations (6) to (20) above. V-V-ΔY ・・・・・・・・・(28)ΔX
-X-X ・・・・・・・・・ (29
)ΔY−＾ ・Δ× ・・・・・・・・・
(30) From these equations (28) to (3o), the optimal control gain Y and shadow first coefficient matrix A in the standard heat load state x are 1! ? , the heat load state changes from the standard state × to Δ×
Even if the JQ condition changes and becomes a state of ×, the control 1 gain ΔY to be corrected can be calculated by 1rI using the equation (30), and the optimal 11) control gain Y when changed from the standard state can be obtained using the equation (28). is understood. Note that the optimal control gain Y and the influence coefficient matrix ^ in the standard state can be determined by calculation or experiment.
A temperature control device in which the 13II 7j method is implemented will be described in detail. As shown in FIG. 1, this embodiment is applied to the conventional temperature control device shown in FIG.
By adding an optimum gain control device 30 to the T'J moderator 18, the P I D ;TJ moderator 18 can be adjusted according to the heat load of the heating furnace 12 as shown in FIG. Each control gain Kp is changed to + and +. As shown in FIG. 2, the optimum gain calculation device ff130 performs the above-mentioned (3) to (5) in the standard heat load state.
Similarly, the constant setter 32 for setting the control gain Y shown in equations and equations (22) as a constant, as in (25) above.
e of the equation:, a constant vl setter 34 for setting the quasi-heat load state x, a constant setter 36 for setting the influence coefficient matrix A shown in the equation (27) above, 24
), the actual heat load state of the heating furnace 12×
the thermal load state setting ``a38'' for setting the thermal load condition; Constant setter 3
The influence coefficient matrix A set in 6 and the above-mentioned '
3 From the difference Δ× of thermal Ω open state calculated with R40, the above (
30) A matrix operator 42 for calculating the control gain ΔY to be corrected using the formula, and the constant setter 32
The difference between the control gain Y in the standard heat load state set in 1 and the control gain ΔY to be adjusted calculated by the matrix calculator 42 is calculated using the above-mentioned formula 28, and the optimum value of 19 changes from the standard state is calculated. and a subtracter 44 for subtracting the control gain Y by 1q. Note that the PID controller 18 and the optimum gain calculation device 30
Between the reading command R1 and the control gain Kp,
Lines 46 to 52 for setting constants of Kl and Ko
is installed. The effects of the embodiment will be explained below. Before controlling the temperature of the heating furnace 12 shown in FIG. 3 with the control device shown in FIG. 1, first, each constant setting device 32 to 3G shown in FIG. The value of the influence coefficient matrix A shown in the control equation shown in equation (22) is set. When controlling the furnace temperature of the heating furnace 12 shown in FIG. 3, the Ryomaro measuring device 16 (as shown in FIG. 1)
In addition to the signal of the furnace temperature T from
N is set and inputted to the heat load state setter 38 of the optimum gain calculation device 30 as the heat load state x. The input heat load state x and the value of the standard heat load state X set in the constant setting device 34 are input to the i-device 40. In this case, the heat load state is set in the heat load state setting device 38, but this value is an actual value (for example, in the example, the actual value of the furnace temperature, outer diameter, wall thickness, and length of the steel pipe) and the number of reactors in the furnace) may be input to the heat load state setting device 38 as an external signal. In the subtracter 40, the deviation of the heat load state from the standard state is calculated by Hasuda based on the above-mentioned equation (29) to be Δ×, and is inputted to the matrix calculator 42. At this time, the influence coefficient matrix A is simultaneously inputted from the constant setter 36 to the matrix operator 42, the calculation of the above-mentioned equation (30) is performed, and the control gain Δ to be made is
Y is calculated. The calculated control gain ΔY is calculated by the subtracter 4
4, and at the same time, the constant setter 32 is input to the subtracter 44.
The standard optimal control gain Y is input from . The subtractor 4
4 performs a matrix calculation of the Wl 3B gain Y when changed from the standard state based on the above equation (28). Then, the calculated optimum control gain Y is set and changed as a constant of + and Ko for each control gain Kp of the P, I, and D functions of the PID controller 14 shown in FIG. This constant is changed by the following procedure. That is, after the change in the control gain Y due to the change in the heating conditions of the material to be heated 10 inserted into the heating furnace 12 is processed by the suitable gain calculation device 30, the change command S is issued. Based on the issued change command S, the PI was sent through line 46.
A reading command R is input to the D controller 18. The PID controller 18 reads line 4 based on the input reading command R.
8.50.52 through P (proportional), r (!?X minutes)
, D (differential) control gain Kp corresponding to each control operation
By reading the new control constants of , +, and Ko and resetting them, the constants are automatically changed. In addition, in the above example, a steel pipe was exemplified as the object to be heated, and heating control based on the above-mentioned formulas (3) to (30) was explained, but the object to be heated and the calculation formula are limited to these. It is also possible to control the temperature of other objects to be heated using Haku's calculation formula 2I+. Further, in the embodiment, P of the PJD controller 18, [
, DI functions, all control gains Kp, +, KO are changed to constants, but the present invention is not limited to this, and when controlling only arbitrary control gains of 1 or 2 by changing constants. It is clear that it can also be applied to [Effects of the Invention] As explained above, according to the present invention, even if the heat load in the furnace fluctuates, the control gain of the I-' [+] controller can be changed in response to the fluctuation. Responsiveness of furnace wet control does not decrease. Therefore, even if the characteristics or load conditions of the heating furnace change, a constant or optimal response can always be obtained, making it possible to set the optimal heating conditions for the material to be heated by 1!7. have an effect. 4. Drawing No. 1m ll'i 7'J m nJ] FIG. 1 is a block diagram showing the configuration of a temperature control device in which the temperature control method for a heating furnace according to the present invention is implemented, and FIG. The optimal gain function F [block diagram showing the device in detail,
FIG. 3 is a piping diagram including a partial block diagram showing an example of the configuration of a heating furnace to which the present invention is applied, and FIG. 4 is a block diagram showing an example of a conventional temperature control device for a heating furnace. . 10... Material to be heated, 12... Heating furnace, 16.
...Temperature measuring device, 18...PID controller, 20.
... Combustion control O1l equipment j126... Combustion device, 30...
-Optimum gain calculation device, 32-36...Constant setter, 38...Heat load condition setter, 40.44...Subtractor, 42...Matrix operator, 46-52... ·line.

Claims (2)

[Claims] (1) In a temperature control method for a heating furnace in which the temperature of the heating furnace is controlled using a PID controller, the amount of heat load fluctuation is determined from the heat load state in the heating furnace, and based on the determined amount of heat load fluctuation. . A heating furnace temperature control method, comprising changing the control gain of the PID controller. (2) In a heating furnace temperature control device that controls the temperature of the heating furnace using a PID controller, the thermal load state in the heating furnace is determined from the dimensional information and heating conditions of the material to be heated inserted into the heating furnace. a calculation means for calculating a heat load variation amount of the heating furnace based on the detected heat load state; and a PID adjustment that obtains a predetermined response performance based on the calculated heat load variation amount. A temperature control device for a heating furnace, comprising: arithmetic means for calculating a control gain of the PID controller; and means for changing the control gain of the PID controller to the calculated control gain.