JP3537215B2 - Heating furnace temperature controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature controller for a multi-zone continuous heating furnace for continuously heating a slab by a heating furnace having a plurality of heating zones.

[0002]

2. Description of the Related Art A heating furnace usually has a length of 30 to 60 m, and its length direction is divided into a plurality of heating zones. Each heating zone is provided with a burner for supplying fuel and air, and the temperature of the heating zone can be controlled almost independently of the other heating zones by adjusting the fuel flow rate. The purpose of heating furnace temperature control is as follows. Heating the slab extraction temperature to the target extraction temperature. To raise the temperature of the slab according to the target temperature rising pattern. Minimize fuel flow.

[0003] By heating the above slab to the target extraction temperature according to the target heating pattern, a high quality rolled product and stabilization of rolling are realized. Further, by minimizing the fuel required for heating, it contributes to energy saving and realizes economical operation. In the past, emphasis was placed on and, but in recent years the demands on the uniformity of product quality, especially mechanical properties (tensile strength, stretchability, etc.) within and between slabs have become strict, and the target temperature rise pattern for each slab has It has been required to heat the slab.

In order to satisfy these requirements, various methods and apparatuses have been conventionally proposed. As a typical example, a method disclosed in Japanese Patent Publication No. 58-25730 discloses a method of multiplying a square of a deviation between a target furnace temperature pattern corresponding to a slab hearth position and a slab temperature corresponding to a hearth position by a weighting coefficient. The temperature of each heating zone is set and controlled in accordance with the value obtained. That is, the slab temperature θ _i after a certain time R ₁ is predicted by a nonlinear partial differential equation representing the temperature distribution inside the slab and the boundary condition formula, and the target temperature θ obtained from the slab prediction hearth position after the certain time R ₁ Calculate and set the furnace temperature that minimizes the evaluation function represented by the following equation in which the deviation from _pi is weighted.

[0005]

(Equation 1) However, J _I : evaluation value W _i : weight of i slab M _I : number of slabs existing in the heating zone to be controlled.

Further, the method disclosed in Japanese Patent Application Laid-Open No. 2-156017 is necessary for setting the temperature of a slab at each position in a furnace to a value on a target temperature rising curve for a predetermined time in the future. The maximum value or weighted average value of the fuel flow rate for each material is used as the fuel flow rate set value for the heating zone. That is, the future i slab average temperature θ for the predetermined time N _3
i (t + N ₃₎ the target temperature θ _pi (t + N ₃₎ in the j-th band fuel flow rate setting value F _si for i slabs required to be substantially _{matched, j}
(t) is obtained by minimizing the evaluation function represented by the following equation.

[0007]

(Equation 2) Where F _j (t + k) is the j-th band fuel flow set value at time (t + k) F _{si, j} (t + k) is the j-th band required fuel flow of the ith slab at time (t + k) λ: weighting factors N ₁ , N ₂ , N ₃ : positive integers (N ₁ ≦ N ₂ ≦ N ₃ ) y _pi (t + k): target trajectory of i slab temperature, N ₃ hours from current slab temperature The linear interpolation is performed up to the slab target temperature θ _pi after the lapse.

As the j-th band fuel flow rate set value F _j (t), the maximum value or weighted average of the required fuel flow rates of all the evaluation target slabs existing in the j-th band is obtained and used.

[0009]

[Problems to be solved by the invention] Japanese Patent Publication No. 58-2573
The method disclosed in No. 0 publication, when restrictions on the furnace temperature change outputting a furnace temperature setting value to be excessive furnace temperature changes the evaluation value J _I (1) below because they are not considered an attempt to minimize There is. If the change in the furnace temperature is too large, the change in the fuel flow rate becomes excessive, so that the purpose of minimizing the fuel flow rate cannot be achieved.

Further, the method disclosed in Japanese Patent Application Laid-Open No. 2-156017 corrects the target trajectory of the slab until after a certain time for the purpose of suppressing an excessive change in fuel flow rate. Different heatings may be provided. Therefore, the product cannot be heated to the desired quality because the product cannot be heated according to the target heating pattern. Also, for each slab, the fuel flow rate set value is obtained by weighted averaging, etc., despite calculating the optimal manipulated variable to raise the temperature along the target trajectory without changing the fuel flow rate much. Therefore, there is no guarantee that the set value is optimal.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and at least one or more slab temperatures from a present time to a certain time later are raised in accordance with a target temperature rising pattern, It is an object of the present invention to obtain a heating furnace temperature control device capable of improving the basic unit.

[0012]

According to a first aspect of the present invention, there is provided a temperature control apparatus for a heating furnace, wherein a furnace temperature set value calculating device for calculating a furnace temperature set value for controlling a temperature of a plurality of heating zones is provided for each time. A slab actual temperature calculating means which starts at intervals, calculates an actual temperature for each slab based on the current furnace temperature and slab information, and a future temperature for each slab when the current furnace temperature is maintained (hereinafter, slab temperature future value) Slab temperature future value calculating means for calculating slab temperature, and a target heating pattern determined in advance for each slab.
Temperature future target value calculating means for calculating the slab future target temperature in the heating furnace based on the temperature, and when the furnace temperature set value of each heating zone is changed by a unit amount based on the actual slab temperature and the current furnace temperature. Coefficient calculation means for calculating an influence coefficient representing the difference between the future temperature of the slab and the future temperature of the slab when the furnace temperature set value is held; a slab temperature future value from the present time to a predetermined time future; Based on the target value and the influence coefficient, the weighted sum of squares of the difference between the target temperature of at least one slab and the future temperature of the slab at every control time from the present to the predetermined time and the future from the present to the predetermined time And a furnace temperature set value calculating means for calculating a furnace temperature set value that minimizes the sum of the weighted square sums of the furnace temperature change amounts at all control times.

According to a second aspect of the present invention, there is provided a heating furnace temperature control device, wherein
The target temperature of at least one slab and the future temperature of the slab at every control time from the current time to the future time, based on the future slab temperature value, the future slab temperature target value and the influence coefficient from the present time to the future time. The sum of the weighted sum of squares of the difference from the sum and the weighted sum of the squares of the furnace temperature change amounts for all control times from the present to the predetermined time in the future is calculated as the furnace temperature change amount per control time, Furnace temperature set value calculation means for calculating a furnace temperature set value to be minimized under temperature and slab temperature upper / lower limit constraints is provided.

According to a third aspect of the present invention, in the heating furnace temperature control device, the furnace temperature set value calculating device further includes a furnace temperature set value calculated by the furnace temperature set value calculating device and a slab actual temperature calculated by the slab actual temperature calculating device. Based on the actual slab temperature, a slab temperature predicted value calculating means for calculating the slab future temperature, a determining means for determining whether or not the slab future temperature satisfies the slab heating constraint, and when the slab heating constraint is not satisfied And weight change means for changing the weight used by the furnace temperature set value calculation means for calculation.

[0015]

The operation of the apparatus for calculating a furnace temperature set value according to the first aspect will be described after the principle thereof has been described. FIG. 4 is an explanatory diagram for explaining a heating state of the slab. FIG. 1 shows a case where one heating zone 1 has three representative slabs S ₁ , S ₂ , and S ₃ , each of which has a target heating curve shown by a solid line, a broken line, and a dashed line. The predicted slab temperature when the temperature is maintained is indicated by a thick line. Here, the problem of the heating furnace temperature control is to calculate the furnace temperature for heating the material so that the slabs in the same zone are closest to the target heating curve from the current time to a preset future time. It can be formulated as follows. That is, the slab S _i
The temperature theta _i, furnace temperature set value change amount [Delta] T u from the current time to the N _u sampling _{times, k (k = 1,2, ...} , N u), the i slabs from the current time to the N _p sampling When the predicted temperature value is θ _{i, j} (i = 1,2,..., N, j = 1,2,..., N _p ) and the target temperature of i slab is θ _{R, i, j} , The furnace temperature set value change amount ΔT _{u, k} (k = 1,
2,…, N _u ).

[0016]

[Equation 3] Where a _{ij is the} weight applied to the temperature deviation at the j-th step of the i-slab λ is the weight applied to the furnace temperature setting change amount. FIG. 5 is an explanatory diagram of the future slab temperature predicted value calculation. In the figure, θ _ij represents a predicted slab temperature (° C.) after j steps. From the figure, the predicted slab temperature value θ _{i, j} after j steps is expressed by the following equation.

[0017]

(Equation 4) Here, θ _{p, i, j} : a predicted value g _{i, j, k} of the i-slab temperature j steps after the current time when the furnace temperature set value is held, and an influence coefficient. Predicted slab temperature change (jC) after j steps from the current time of i-slab due to the change of the furnace temperature set value by (k-1) steps from the current time. By definition, g _ijk = 0 (k> j). ΔT _{u, k} : A furnace temperature set value change amount (° C.) after (k−1) steps (k = 1, 2,..., _Nu ).

In the above equation (4), the influence coefficient g _ijk can be obtained by using a heating furnace simulator simulating the dynamic characteristics of the furnace and the furnace temperature control device. As an example of the heating furnace simulator, a calculation formula and a method of obtaining the influence coefficient will be described below. The transfer function from the furnace temperature set value change to the furnace temperature change is expressed by the total dynamic characteristic of the furnace temperature control device and the dynamic characteristics of the heating furnace. The transfer function is controlled to have a certain value. An example of a response from a change in the furnace temperature set value to a change in the furnace temperature in this case is given by the following equation.

[0019]

(Equation 5) Here, T: furnace temperature _Tc : furnace temperature set value _Tf : furnace temperature change time constant t: time. The actual slab temperature value at the previous calculation time is θ
When (x, t) (x is a distance taken in the slab thickness direction), the slab temperature for a certain period of time is calculated using this as an initial value by a known heat conduction equation shown in the following equation.

[0020]

(Equation 6) The boundary condition is expressed by the following equation.

[0021]

(Equation 7) Where σ: Stefan-Boltzmann constant φ _CG : Overall heat absorption rate T: Furnace temperature h: Slab thickness.

Using the above equations (5) to (8), when the heating zone furnace temperature set value is held and when the unit amount is changed in each step from the present to the _Nu step, a certain time from the present to the future is used. The slab temperature at each control timing up to is calculated. The difference between the slab temperature when the furnace temperature set value is changed by a unit amount and the slab temperature when the furnace temperature set value is held is the influence coefficient.

G _ijk = (θ _{i, j, k} −θ _{p, i, j} ) / ΔT _c (9) where θ _{i, j, k} : furnace temperature setting of the slab existing heating zone at the kth step from now Predicted i-slab temperature θ _{p, i, j at the} j-th step from the present when the value is changed by a unit amount: Predicted i-slab temperature ΔT _{c at the} j-th step from the present when holding the furnace temperature set value This is the set value change amount.

When there is no restriction on the change of the furnace temperature, an optimum furnace temperature correction amount that minimizes the evaluation function J can be _obtained by partially differentiating the evaluation function J with the furnace temperature set value correction amount ΔT _{u, k.} . Substituting equation (4) into equation (3), partially differentiating the evaluation function J with the furnace temperature set value correction amount ΔT _{u, k} , and letting the furnace temperature set value change amount that makes it zero be ΔT _{c, k} The following equation is obtained.

[0025]

(Equation 8) When the above equation (10) is represented by a matrix, the following equation is obtained. H · u = b (11) where

[0026]

(Equation 9) However, the elements of the matrix are as follows.

[0027]

(Equation 10) If the weight λ is selected so that the matrix H becomes regular, the furnace temperature set value change vector u can be obtained by the following equation. u = H ⁻¹ · b (18) The furnace temperature set value T _{c, k} (k = 1,2,..., _Nu ) is given by the following equation (4) if the previous furnace temperature set value is T _{c, 0} . By definition,

[0028]

(Equation 11) The furnace temperature target value actually used for control is T _{c, 1} , and the other (T _{c, k} : k = 2,3, ..., N _u ) can be used for operator guidance and the like.

Therefore, in the furnace temperature set value calculating device according to the first aspect, the slab actual temperature calculating means includes information on the current furnace temperature and the slab, for example, the in-furnace position of the slab, the thickness, and the like.
Based on the width, length, material, charging temperature, actual temperature at the previous calculation time, etc., the actual temperature of each slab is calculated using equations (6) to (8), and the slab temperature future value calculating means is also the same.
The future temperature of each slab is calculated using the equations (6) to (8).
The slab temperature future target value calculating means calculates a future target temperature for each slab in the heating furnace based on the slab information. The influence coefficient calculating means uses the equations (5) to (8) based on the actual temperature of the slab and the current furnace temperature, and uses equations (5) to (8) to hold the furnace temperature set value for each heating zone and from the present to the _Nu step future. If the heating zone furnace temperature set value is changed by a unit amount in the step, the slab temperature for each control timing from the present to the future for a certain period of time is calculated, and the furnace temperature set value is further converted to the unit using the equation (9). The influence coefficient is calculated based on the difference between the slab temperature when the amount is changed and the slab temperature when the furnace temperature set value is held. Then, based on the slab temperature future value from the present to the predetermined time in the future, the slab temperature future target value and the influence coefficient, the furnace temperature set value calculating means uses the formulas (18) and (19) to calculate from the present to the predetermined time in the future. Minimize the sum of the weighted sum of the squared weights of the future temperature deviations of all the slabs at all control times and the weighted sum of the squares of the furnace temperatures at all the control times from the present time to the future for a predetermined time. Calculate the furnace temperature setting. Further, in the furnace temperature control device, for example, the fuel supply amount is controlled so that the furnace temperature set value matches the detected temperature.

Next, the operation of the temperature control device according to the second aspect will be described after the principle thereof has been described. When there are upper and lower limits of the furnace temperature set value and upper and lower limits of the change amount of the furnace temperature set value, the furnace temperature set value change amount and the furnace temperature set value become excessive because the above calculation cannot consider the constraint conditions. There is fear. In addition, since the upper and lower limits of the slab temperature cannot be considered, there is no guarantee that heating of a slab with strict heating restrictions can be controlled in accordance with a target heating pattern. To solve this problem, it is necessary to find an optimal solution with constraints. Therefore, the following expression is expanded. First, in equation (3)
(4) By substituting the equation and transforming it, the following equation is obtained.

[0031]

(Equation 12) Furnace on temperature set point, lower limit _{T u, min ≦ T u,} k ≦ T u, is represented by _max. Here, the subscripts min and max represent the upper and lower limits, respectively. On the other hand, the furnace temperature set value after k steps, _{Tu, k}
Becomes as follows.

[0032]

(Equation 13) As a result, the upper and lower limit of the furnace temperature set value is N _u as follows:
It is expressed by constraint equations.

[0033]

[Equation 14] Furnace on temperature set value and lower limit constraint is represented by N _u number of constraints as follows. ΔT _{u, min} ≦ ΔT _{u, k} ≦ ΔT _{u, max} (k = 1, 2,..., _Nu ) (23) where the subscripts min and max represent the upper and lower limits of the furnace temperature set value change amount. Assuming that the upper and lower limits of the target heating pattern (target temperature) are Δθ _min and Δθ _max , the upper and lower limits of the slab temperature are expressed by the following equations. θ _{min, i, j} ≦ θ _{i, j} ≦ θ _{max, i, j} (24) (i is a set of slab numbers having strict constraints, j = 1,2,
…, N _p ) where θ _{min, i, j} = θ _{R, i, j} −Δθ _min … (25) θ _{max, i, j} = θ _{R, i, j} + Δθ _max … (26) (i is a severe constraint A set of slab numbers with conditions, j = 1,2,
…, N _p ) where θ _{i, j} : _{j of} the ith slab (slab with strict restrictions)
The predicted temperature at the step future time, defined by equation (4) θ _{R, i, j} : the current j when the temperature of the heating zone where the ith slab (slab with strict restrictions) exists is held This is the predicted temperature of the i-th slab at the time of the step future. Substituting equations (4), (25), and (26) into equation (24) and rearranging, the slab temperature constraint is given by (the number of slabs of slabs × N _p ) as shown in the following equation. Can be

[0034]

(Equation 15) (I is a set of slab numbers with strict constraints, j = 1,2,
…, N _p ) Therefore, under the constraints of equations (22), (23) and (27), 2
The optimal furnace temperature set value change amount that minimizes the evaluation function of equation (20) can be obtained using the following programming method. The furnace temperature set value calculating means according to claim 2 is based on this principle, and inputs a slab temperature future value, a slab temperature future target value, and an influence coefficient from the present to a predetermined time in the future, and (22), ( 23) and (2
Under the constraint conditions of equation (7), the optimum furnace temperature set value change amount that minimizes the evaluation function of equation (20) is obtained, and the furnace temperature set value is calculated using equation (19).

Next, the operation of the temperature control device according to the third aspect will be described after the principle thereof has been described. Although the weight a _ij is required in the above-described furnace temperature set value calculation formula, since the count can be innumerable depending on the operating conditions and the arrangement of the slabs in the heating furnace, the weight set as the initial value is appropriate. There is no guarantee. To solve this,
With the furnace temperature setting value of the operation result performs prediction calculation of the slab temperature from present time until after a certain time, the heating zone outlet temperature of the slab to be extracted or to move the heating zone within from current until after N _p Step Alternatively, it is determined whether or not the extraction temperature is equal to or higher than the target value, and if there is a slab equal to or lower than the target value, the weight is changed and the furnace temperature set value is calculated again. The initial value of the weight can make each heating zone outlet temperature close to the target temperature by increasing the weight for the slab on the heating zone outlet side. The weight of until after N _p step by decreasing according to the number of steps is increased, it is possible to reduce the prediction error is estimated time from the present time increases with longer. That is, an example of the initial value of the weight is represented by the following equation.

A _1,1 = a ₀ (28) a _{i, 1} = (k ₁ ) ⁱ a _i-1,1 (i = 2,3,..., N) (29) a _{i, j} = (K ₂ ) ^j _{ai, j-1} (i = 1,2,3,…, n / j = 2,3,…, N _p )… (30) where a ₀ , k ₁ , k ₂ : constants n: number of slabs in the target heating zone N _p : number of predicted steps.

[0037] Therefore, the slab temperature future predicted value calculating means according to claim 3 of the slab to be present in the heating zone of interest, the slabs extracted either moves the heating zone from the present time until after N _p Step pressurized The tropical exit temperature or the extraction temperature is predicted and calculated, and the determination means determines whether the temperature is equal to or lower than the target temperature. If the heating zone outlet temperature or the extraction temperature of all the determination target slabs is equal to or higher than the target value, the furnace temperature set value calculating means outputs the calculated furnace temperature set value as it is. If there is a slab that is equal to or less than the target value, the weight _{ai, j} for the slab is set at a predetermined rate until the heating zone outlet temperature or the extraction temperature of all the slabs to be determined is equal to or greater than the target value. The calculation of the furnace temperature set value is increased and the calculation is repeated. The weight changing means outputs the _{ai, j} and gives it to the furnace temperature set value calculating means, and also calculates the weight λ.

[0038]

(Equation 16) Is changed to be constant, the response of the slab temperature control can be kept constant.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. FIG. 1 is a block diagram showing a configuration of an embodiment corresponding to claim 1. In FIG.
Has a plurality of heating zones arranged continuously. Furnace temperature detectors 2a, 2b, 2c are provided in these heating zones.
A burner (not shown) for supplying fuel and air is provided, and the furnace temperature controller 3 controls the flow rate control valve 2A for the burner.
It is designed to operate 2B and 2C. In this case, the furnace temperature control device 3 includes the respective temperature detection values of the furnace temperature detectors 2a, 2b, and 2c,
The furnace temperature set value calculated by the furnace temperature set value calculation device 4 is input, and the furnace temperature control device 3 operates the flow control valves 2A, 2B, 2C so that the difference becomes zero.

On the other hand, the furnace temperature set value calculating device 4 includes a slab actual temperature calculating means 5 for calculating the actual temperature θ for each slab based on the furnace temperature T detected by the furnace temperature detector and the slab information, A slab temperature future target value calculating means 6 for calculating a slab future target temperature θ _R in the heating furnace, and a future temperature θ _ij for each slab when the current furnace temperature is held based on the actual temperature θ for each slab. A slab temperature future value calculating means 7 to perform, an influence coefficient calculating means 8 for calculating an influence coefficient g _ijk based on the current furnace temperature T and the actual temperature θ for each slab,
Furnace temperature set value calculating means 9 for calculating a furnace temperature set value _Tc based on the calculated slab future target temperature θ _R , future temperature θ _{ij for} each slab, and influence coefficient g _ijk .

The operation of this embodiment will be described below. The actual slab temperature calculating means 5 is based on the current furnace temperature T and the slab information (the slab furnace position, thickness, width, length, material, charging temperature, actual temperature at the previous calculation time, etc.)
Calculate the actual temperature θ for each slab using equation (8). The slab temperature future target value calculating means 6 calculates a slab future temperature in the heating furnace based on the slab information and the elapsed time. The slab temperature future value calculating means 7 calculates the future temperature θi _{, j} for each slab when the current furnace temperature is maintained, using the equations (6) to (8). The influence coefficient calculation means 8 calculates the influence coefficient g between the furnace temperature change amount and the slab temperature change amount when the furnace temperature set value of each heating zone is changed by a unit amount based on the actual temperature θ and the current furnace temperature T for each slab.
Calculate _ijk . That is, using the equations (5) to (8), the furnace temperature set value of each heating zone is held, and the furnace temperature set value of each heating zone at each step from the present to the _Nu The slab temperature at each control timing from the present time to the future for a predetermined time when the slab temperature is changed is calculated. Further, using the equation (9), the influence coefficient g _ijk is calculated based on the difference between the slab temperature when the furnace temperature set value is changed by a unit amount and the slab temperature when the furnace temperature set value is held. The furnace temperature set value calculation means 9 calculates a future slab temperature value θ _ij , a future slab temperature target value θ _R, and an influence coefficient g _ijk from the present time to a predetermined time in the future.
, And weighted sum of squares of all future temperature deviations for all control times from the current time to the predetermined time and the future using the formulas (18) and (19). A furnace temperature set value _Tc for minimizing the sum of the weighted square sum of the furnace temperature change amount for each furnace temperature is calculated and added to the furnace temperature control device 3. Therefore, the furnace temperature control device 3 calculates a fuel flow manipulated variable corresponding to the furnace temperature set value _Tc, and determines the required fuel flow rate in the heating furnace main body 1.
To control the furnace temperature to a furnace temperature set value. Thus, according to this embodiment, the slab can be accurately heated to the target extraction temperature in accordance with the heating pattern.
Further, since a change in the furnace temperature set value can be suppressed, the fuel consumption rate can be improved, and energy saving operation can be achieved.

FIG. 2 is a block diagram showing the configuration of an embodiment according to the second aspect. In the figure, components denoted by the same reference numerals as those in FIG. 1 indicate the same components. Then, the furnace temperature set value calculating means 9 in FIG. 1 is removed, and a furnace temperature set value calculating means 10 is provided instead. Hereinafter, the operation of this embodiment will be described. However, since the elements other than the furnace temperature set value calculating means 10 are completely the same as those described with reference to FIG. explain. The furnace temperature set value calculating means 10 inputs the slab temperature future value θ _ij , the slab temperature future target value θ _R and the influence coefficient g _ijk from the present to the future for a predetermined time, and obtains the equations (22), (23) and (27). Based on the constraint conditions of the equation, the amount of change in the furnace temperature set value that minimizes the equation (20) is obtained using the quadratic programming, and the furnace temperature set value _Tc is calculated using the equation (19). . According to this embodiment, when there are upper and lower limits of the furnace temperature, and when there is an upper and lower limit of the change amount of the furnace temperature, the furnace temperature set value in consideration of the constraint condition can be calculated. The slab can be heated easily and in accordance with the target heating pattern. In addition, since the upper and lower limits of the slab temperature can be considered, it is possible to control the heating of the slab having the strict heating constraints so as to fall within the upper and lower limits of the target heating pattern. Therefore, the heating of the high value-added material becomes easy, and the production of a product having new mechanical properties becomes possible.

FIG. 3 is a block diagram showing the structure of the third embodiment. In the figure, components denoted by the same reference numerals as those in FIG. 1 indicate the same components. Then, the components shown in FIG. 1, based on the furnace temperature setting value calculating means 9 in the obtained furnace temperature setting value T _c, the slab actual temperature calculating means 5 in the obtained slab actual temperature theta, future temperature theta _ij Slab temperature future predicted value calculating means 20 for calculating the slab heating constraint, and determining means 21 for determining whether the calculated slab future temperature θ _ij satisfies the slab heating constraint. And a weight changing means 22 for adding the changed weight λ to the furnace temperature set value calculating means 9 is added. Hereinafter, the operation of this embodiment will be described with respect to elements newly added to the configuration of FIG. The calculating means 20 inputs the furnace temperature set value _Tc calculated by the furnace temperature set value calculating means 9 and the actual slab temperature θ calculated by the actual slab temperature calculating means 5, and calculates the future slab temperature θ _ij . The determining means 21 determines whether or not the future slab temperature θ _ij satisfies the slab heating constraint. Weight changing means 22
Changes the weight when the slab heating constraint is not satisfied, and gives the changed weight to the furnace temperature set value calculating means 9. According to this embodiment, the heating zone outlet temperature or extraction temperature of all the slabs to be moved or extracted from the present time to a certain time in the future can be set to the target temperature or higher, so the slab temperature with extremely high accuracy Control becomes possible.

The calculating means 20 and the judging means 21 shown in FIG.
Also, the weight changing means 22 can be added to the furnace temperature set value calculating device 4 shown in FIG. 2, and also in this case, the slab temperature can be controlled with high accuracy as described above. Incidentally, the prediction period N _p, the slab in the heating furnace is also intended to move from the heating zone in the following heating zone. Therefore, the evaluation function of equation (3) cannot optimize the entire heating furnace. In order to solve this problem, consider setting an evaluation function considering a plurality of heating zones, and finding a furnace temperature set value that minimizes the evaluation function.

Now, the temperature of the slab S _i is θ _i , and the change amount of the furnace temperature in the k heating zone from the current time to the number of _Nu samplings is ΔT _{k, L} (L = 1, 2, 3,..., _Nu ). , The temperature predicted value of the i slab from the current time to N _p sampling is θ _{i, j} (i = 1,2,
…, N / j = 1,2,…, N _u ), and the target temperature of the i slab is θ _{R, i, j}
Then, the following evaluation function is set.

[0046]

[Equation 17] Here, λ: weight applied to the furnace temperature change amount m: number of heating zones By performing the same study as in equation (3), the furnace temperature change amount ΔT _{k, L} (k = 1,2,..., M / L = 1,2 in the k heating zone to minimize equation (31) , ..., _Nu / m = number of heating zones). The result is the same as the description after the expression (3), and the description is omitted. Thus, the same control as in the above-described embodiments can be performed on a slab that moves from a heating zone to the next heating zone.

[0047]

As is apparent from the above description, according to the present invention, the temperature of the slab can be controlled very accurately in accordance with the target heating pattern, and the unit fuel consumption can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a third embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a heated state of a slab for explaining the principle of the present invention.

FIG. 5 is an explanatory diagram of a future temperature predicted value calculation of a slab in order to explain the principle of the present invention.

[Explanation of symbols]

1. Heating furnace body 2a, 2b, 2c Furnace temperature detector 2A, 2B, 2C Flow control valve 3 Furnace temperature control device 4 Furnace temperature set value calculator 5 Slab actual temperature calculation means 6 Slab temperature future target value calculation means 7 Future slab temperature calculation means 8 Influence coefficient calculation means 9,10 Furnace temperature set value calculation means 20 Slab temperature future prediction value calculation means 21 Judgment means 22 Weight changing means

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI G05D 23/19 G05D 23/19 G J (72) Inventor Masanori Ebihara 1-1-28 Kitahonmachidori, Chuo-ku, Kobe-shi, Hyogo Prefecture Kawasaki Steel Corporation (72) Inventor Yoshiro Seki 1 Toshiba-cho, Fuchu-shi, Tokyo Toshiba Corporation Fuchu Factory (72) Inventor 1-Henshi Toshiba-cho, Fuchu-shi, Tokyo Toshiba Fuchu Factory (72) Inventor Hiroyuki Shinonaga 1-1-1, Shibaura, Minato-ku, Tokyo Inside the head office of Toshiba Corporation (72) Inventor Yoshinobu Okiya 1 Toshiba-cho, Fuchu-shi, Tokyo Fuchu, Tokyo In the factory (56) References JP-A-5-209235 (JP, A) JP-A-4-17621 (JP, A) JP-B-6-6735 (JP, B2) JP-B-58-25730 (JP, B1) (58) Field surveyed (Int.Cl. ⁷⁾ , DB name) C21D 11/00 C21D 9/00 C21D 1/52

Claims (3)

(57) [Claims] 1. A furnace temperature set value calculating device for calculating a furnace temperature set value of each heating zone when continuously heating a slab in a furnace having a plurality of heating zones, and a calculated furnace temperature set value. And a furnace temperature controller for controlling the temperature of each heating zone according to the following. The furnace temperature set value operation device is started at each time interval, and the current furnace temperature and slab information A slab actual temperature calculating means for calculating an actual temperature for each slab, a slab temperature future value calculating means for calculating a future temperature for each slab when the current furnace temperature is maintained, and a predetermined target for each slab. A slab temperature future target value calculating means for calculating a slab future target temperature in the heating furnace based on the heating pattern; and a unit amount change of the furnace temperature set value of each heating zone based on the actual slab temperature and the current furnace temperature. If the slab is not An influence coefficient calculating means for calculating an influence coefficient representing a difference between the temperature and the future temperature of the slab when the furnace temperature set value is held; a slab temperature future value, a slab temperature future target value and an effect from a current time to a predetermined time in the future; Based on the coefficient, a weighted sum of squares of the difference between the target temperature of at least one slab and the future temperature of the slab at every control time from the present to the predetermined time future and all the control from the present to the predetermined time future A furnace temperature set value calculating means for calculating a furnace temperature set value for minimizing a sum of a weighted squared sum of a furnace temperature change amount for each time and a furnace temperature set value calculating means. 2. A furnace temperature set value calculating device for calculating a furnace temperature set value of each heating zone when continuously heating a slab in a furnace having a plurality of heating zones, and a calculated furnace temperature set value. And a furnace temperature controller for controlling the temperature of each heating zone according to the following. The furnace temperature set value operation device is started at each time interval, and the current furnace temperature and slab information A slab actual temperature calculating means for calculating an actual temperature for each slab, a slab temperature future value calculating means for calculating a future temperature for each slab when the current furnace temperature is maintained, and a predetermined target for each slab. A slab temperature future target value calculating means for calculating a slab future target temperature in the heating furnace based on the heating pattern; and a unit amount change of the furnace temperature set value of each heating zone based on the actual slab temperature and the current furnace temperature. If the slab is not An influence coefficient calculating means for calculating an influence coefficient representing a difference between the temperature and the future temperature of the slab when the furnace temperature set value is held; a slab temperature future value, a slab temperature future target value and an effect from a current time to a predetermined time in the future; Based on the coefficient, a weighted sum of squares of the difference between the target temperature of at least one slab and the future temperature of the slab at every control time from the present to the predetermined time future and all the control from the present to the predetermined time future Furnace temperature setting that minimizes the sum of the furnace temperature change amount at each time and the weighted sum of squares, based on the furnace temperature change amount per control time, maximum and minimum furnace temperatures, and slab temperature upper and lower limits And a furnace temperature set value calculating means for calculating a value. 3. A slab temperature future predicted value calculation for calculating a slab future temperature based on the furnace temperature set value obtained by the furnace temperature set value calculation means and the slab actual temperature obtained by the slab actual temperature calculation means. Means, determining means for determining whether or not the slab future temperature satisfies the slab heating constraint, and weight change for changing the weight used by the furnace temperature set value calculating means for the calculation when the slab heating constraint is not satisfied. 3. The temperature control device for a heating furnace according to claim 1, further comprising: means.