JPH076001B2 - Furnace temperature setting device for continuous heating furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a furnace temperature setting device for a continuous heating furnace that heats a heated material piece (hereinafter referred to as a steel piece) such as a slab or a billet. More specifically, the present invention relates to a furnace temperature setting device for a continuous heating furnace that individually sets the furnace temperature of each control zone in order to individually control each furnace temperature of a plurality of control zones through which a billet continuously passes.

(Prior Art) As a typical conventional continuous heating furnace, there is a multi-zone continuous heating furnace having three control zones of a pre-tropical zone, a heating zone and a soaking zone.

This multi-zone continuous heating furnace is provided with a burner that burns the injected fuel, a furnace temperature sensor that detects the furnace temperature, a furnace temperature detection value by this furnace temperature sensor, and a furnace temperature setter for each control zone. And a control device for controlling the deviation of the set value of the furnace temperature to approach zero, and the temperature is independently controlled in each control zone.

The billet is heated while moving sequentially through the pre-tropical zone, the heating zone and the soaking zone, and is baked at the extraction port so as to reach the extraction target temperature. Generally, a plurality of steel pieces are present in these control zones, and the size and material of the steel pieces, the extraction target temperature, the surface temperature limit value, etc. are not necessarily the same. When the size, material, extraction target temperature, surface temperature limit value, etc. of the billet are different, the furnace temperature must be reset every time the billet is extracted, and if the setting is not appropriate,
The steel slab in the furnace may not be baked to the extraction target temperature, or conversely may be overbaked during extraction.

In addition, the size, material, and
Considering the extraction target temperature and surface temperature limit value, etc., calculate an appropriate furnace temperature set value and set the furnace temperature in the heating furnace even if it is set in the furnace temperature control device. There is a considerable time delay before the value is controlled. Therefore, it is difficult to perform fine control by paying attention to individual steel pieces.

In order to solve such a problem, taking into account the characteristics of the heating furnace, pay attention to the steel piece with the least burnt out of the multiple steel pieces mixed in the heating furnace, and extract the steel piece. It is conceivable to set the furnace temperature of the heating furnace so that the extraction target temperature can be reached at such a time. However, in this furnace temperature setting method, if even one slab with insufficient burning exists in the same control zone of the heating furnace, the furnace temperature will be set higher by paying attention to the slab. Therefore, it exists in the same control zone,
Many of the preceding and subsequent slabs of underburned slabs are burned considerably higher than the extraction target temperature of each slab.

In addition, as another furnace temperature setting method, the extraction temperature of each steel strip in the time from the current time to the time when the steel strips mixed in the same control zone of the heating furnace are extracted while considering the characteristics of the heating furnace. To extract the temperature difference between the extraction temperature estimated value and the extraction target temperature, or minimize the squared sum of the temperature differences until the billets mixed in the same control zone are extracted from the current time. A method of calculating the furnace temperature set value at the time of is considered. In this furnace temperature setting method, since the furnace temperature set value is calculated by paying attention to all the steel pieces mixed in the same control zone of the heating furnace, the calculated furnace temperature set value is the average furnace temperature set value. Becomes For this reason, the extraction temperature of the billet that is the least burnt among the billets mixed in the same control zone of the heating furnace may be considerably lower than the extraction target temperature. At this time, if the extraction temperature of the steel slab becomes lower than the allowable rolling extraction temperature in the next process, for example, delay the extraction until the steel slab is heated to the allowable extraction temperature allowing rolling, that is, the heating furnace. I have to wait. If this waiting for the heating furnace occurs, the rolling production schedule will be significantly changed.

(Problems to be Solved by the Invention) The present invention has been made in order to solve the above-mentioned problems in the prior art. Even when steel pieces with different burnt states are mixed in the control zone, they are overburned or insufficiently burned. It is an object of the present invention to provide a furnace temperature setting device for a continuous heating furnace that enables highly accurate temperature control without any problems.

[Structure of Invention]

(Means for Solving the Problem) A furnace temperature setting device for a continuous heating furnace according to the present invention is provided with material data specific to a material to be heated, process data specific to a process, and a material to be heated obtained as a result of past calculation. A memory for storing the estimated temperature data, and a first calculating means for calculating the extraction scheduled pitch until the material piece to be heated in the furnace is extracted from the continuous heating furnace based on the process data stored in the memory. Second operation means for calculating the future position of the material to be heated in the furnace at the scheduled extraction time calculated from the expected extraction pitch calculated by the first calculation means, and the furnace temperature detection value of each control zone Third computing means for estimating the current temperature of the heated material piece based on the estimated temperature data stored in the memory and sequentially updating the estimated temperature data of the memory, and the heated material piece at each position in the furnace. Eye Each position in the furnace of the heated material piece is stored based on the future position of the heated material piece calculated by the second calculation means and the material data and the process data stored in the memory by storing the standard temperature as a target temperature curve. Target temperature curve indexing means for indexing the target temperature and the optimum piece of material to be heated for calculating the furnace temperature setting value are deduced, and the calculation method of the optimum furnace temperature setting value and the optimum furnace temperature setting value are calculated. A knowledge storage unit that stores a rule for determining an optimum weighting coefficient to be used at some time, material data stored in the memory, a scheduled extraction pitch of the heated material piece calculated by the first calculation means, The furnace position of the piece of material to be heated calculated by the second calculating means, the current temperature of the piece of material to be heated calculated by the third calculating means, and the furnace of the piece of material to be heated indexed by the target temperature curve indexing means Based on the target temperature at each position and the rule stored in the knowledge storage unit, the most suitable material piece to be heated for calculating the set value in the furnace is deduced, and the optimum method for calculating the set value of the furnace temperature is calculated. And an optimum weighting coefficient used to calculate the optimum furnace temperature set value, an inference unit, each data used for inference by this inference unit, and the optimum furnace temperature setting inferred by the inference unit Based on the value calculation method and the optimum weighting coefficient, the furnace temperature set value is calculated so that each material temperature is secured at the extraction target temperature when the material piece to be heated is extracted from the continuous heating furnace. (Operation) A steel slab S existing in one control zone of the heating furnace is present at a position X ₀ at time t ₀ , as shown in FIG. 2, It is assumed that the reactor was located at position X ₁ at time t ₁ . The steel piece S has a target value of the material average temperature at each position in the direction toward the extraction port, and a series of these target values is a target temperature curve A.
Here, assuming that the target temperature at the position X ₀ is T ₀ and the target temperature at the position X ₁ is T ₁ , the time Δt (= t ₁ −t ₀ ) for the billet S to move from the position X ₀ to the position X ₁ Inside, it is necessary to heat from the current temperature θ ₀ to the target temperature T ₁ . This temperature difference Δθ (=
The furnace temperature θ _g required to heat only T ₁ −θ ₀ ) can be calculated by the following equation by using the surface temperature of the material.

Where c: specific heat (Kcal / kg ° C) ρ: density (kg / m ³ ) b: width of billet (m) σ: Stefan Boltzmann constant Φ _CGu ： upper overall heat absorption Φ _CG1 : lower overall heat absorption Δθ: Temperature deviation (= T ₁ −θ ₀ ) (° C) _Δt : Time interval (= t ₁ −t ₀ ) (hr) θ _g : Furnace temperature (° C) θ _u : Upper surface temperature of steel slab (° C) ) Θ ₁ : The lower surface temperature (° C) of the steel slab.

On the other hand, one of the control zone of the furnace, as shown in FIG. 3, n pieces of steel slab _{S 1, S 2, S 3} , ..., S n-1, S n are each spout (drawing , The right side) and the positions (on the left side) X ₁ , X
₂ , X ₃ , ..., X _n-1 , X _n , and the scheduled extraction times of these steel pieces are t ₁ , t ₂ , t ₃ , ..., t _n-1 , t _n , respectively. The current temperatures of the steel billets are θ ₁ , θ ₂ , θ ₃ , ..., θ _n-1 ,
If θ _n and the target temperature curves of these steel pieces are A, by using the above equation (1), the furnace temperatures θ _g1 , θ _g2 , and θ _g3 required for heating to the extraction target temperatures, respectively, can be obtained. ，
, Θ _gn−1 , θ _gn can be calculated.

These furnace temperatures θ _g1 , θ _g2 , θ _g3 , ..., θ _gn-1 , θ
_As shown in FIG. 3, _gn is highest near the extraction port and may decrease in order from the extraction port, or as shown in FIG. 4, it may fluctuate slightly in a narrow temperature range. Alternatively, as shown in FIG. 5, the steel piece S gradually decreases with increasing distance from the extraction port.
Only the furnace temperature θ _{gn of n} may _jump out and become high.

The present invention compares the target temperature of the steel slab and the current temperature, and selects the calculation method of the furnace temperature set value θ _g , _{set from} the following three, for example.

(1) The furnace temperatures θ _g1 , θ _g2 , θ _g3 , ..., θ _gn−1 , θ _gn are
As shown in FIG. 3, when it is predicted that the one close to the extraction port is the highest, and that it becomes lower as the distance from the extraction port increases, pay attention to the steel piece S ₁ on the extraction port side and pay attention to the steel piece S ₁ The furnace temperature θ _g1 obtained from the above is used as the furnace temperature set value θ _g , _set .

(2) The furnace temperatures θ _g1 , θ _g2 , θ _g3 , ..., θ _gn−1 , θ _gn are
As shown in FIG. 4, when there are slight variations in a narrow temperature range, all the steel pieces S ₁ , S ₂ , S ₃ , ..., S _n-1 , S
_Paying attention to _n , the furnace temperatures θ _g1 , θ _g2 , θ _g3 , ..., θ _gn−1 ,
θ _gn is weighted and averaged to obtain an average furnace temperature _g , and this average furnace temperature _g is set as a furnace temperature set value θ _g , _set . There are the following methods as an example of the weighted averaging method, and one of them is selected.

(A) All n pieces of steel are given the same weight.

(B) A greater weight is given to the steel piece on the extraction port side.

(C) Out of the n pieces of steel, more weight is given to a steel piece that is insufficiently burnt (having a material temperature lower than the target temperature curve).

(3) The furnace temperatures θ _g1 , θ _g2 , θ _g3 , ..., θ _gn−1 , θ _gn are
As shown in FIG. 5, although the temperature _gradually decreases as the distance from the extraction port increases, when only the furnace temperature θ _gn of the steel piece S _{n jumps} out and becomes higher, the steel piece S _n with the most insufficient burning is found. Focusing attention, the furnace temperature θ _gn is set as the furnace temperature set value θ _g , _set .

For this purpose, first, the material data and process data input via the input means are stored in the memory, while the second
The calculation means calculates the future position of the control band at each extraction time of the steel slabs S ₁ , S ₂ , S ₃ , ..., S _n−1 , S _n .
Then, the steel pieces S ₁ , S ₂ , S ₃ , ..., S are calculated by the third calculating means.
_n-1, to estimate the current temperature of each of the S _n to be stored in the memory.

Next, the target temperature curve indexing means uses the billets S ₁ , S ₂ , S ₃ , ..., S
The target temperature of the billet is indexed based on the future positions of _n-1 and _Sn , and the material data and the process data.

On the other hand, a rule for inferring the most suitable billet for calculating the furnace temperature set value and determining the optimum furnace temperature set value calculation method and the optimum weighting coefficient used when calculating the optimum furnace temperature set value is established. It is stored in the knowledge storage unit in advance.

Therefore, the material data stored in the memory, the expected extraction pitch of the billet calculated by the first calculation means, the second
The in-furnace position of the billet calculated by the calculating means, the present temperature of the billet calculated by the third calculating means, and the target temperature at each position in the furnace of the billet indexed by the target temperature curve indexing means, Also, based on the rules stored in the knowledge storage unit, the most suitable billet for calculating the furnace temperature set value is inferred, and the optimum furnace temperature set value calculation method and the optimum furnace temperature set value are calculated. The optimum weighting factor used in the calculation is inferred. Based on each data used for this inference and the optimum furnace temperature setpoint calculation method and the optimum weighting coefficient obtained by the inference, the individual material temperature is determined when the billet is extracted from the continuous heating furnace. The furnace temperature set value of each control zone is calculated so as to ensure the extraction target temperature.

As described above, the operating know-how of the heating furnace operator is stored as a knowledge base, and this is used to infer the most suitable slab for calculating the furnace temperature set value from the baked state of the slab in the furnace. , Even if steel pieces with different baked states are mixed in the heating furnace,
The optimum furnace temperature set value can be obtained at all times, whereby high-precision temperature control without overburning or underburning can be achieved.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of the present invention together with a control system of a continuous heating furnace. In the figure,
The continuous heating furnace 2 provided with burners in the heating zone and each control zone of the soaking zone is provided with a billet extraction means 3 for extracting a billet from the extraction port according to the rolling schedule. Further, the continuous heating furnace 2 includes a furnace temperature sensor 5 for detecting the furnace temperature and a furnace temperature control means 4 for controlling the furnace temperature by adjusting the fuel injection amount of the burner for each control zone. Further, the output signal of the furnace temperature sensor 5 and the billet extraction signal of the continuous heating furnace 2 are input to calculate the furnace temperature set value, and the billet extraction command is sent to the billet extraction means 3 to the furnace temperature control means 4. A furnace temperature setting device 10 for providing a furnace temperature setting signal is provided.

Here, the furnace temperature setting device 10 is intended to control the soaking zone having a billet extraction port, the billet size, the material, the billet specific material data such as the surface temperature limit value, and the heating step. An input unit 11 for inputting process-specific process data such as type, extraction target temperature, required time, etc., and a memory 12 for storing the input data from the input unit 11 and for storing the current temperature data for estimating the current temperature. The extraction pitch calculating means 13 for calculating the extraction scheduled pitch until the steel piece is extracted from the soaking zone of the continuous heating furnace 2, and the inside of the steel piece furnace at the extraction scheduled time obtained from the extraction scheduled pitch calculated here Position calculating means 14 for calculating the future position in the, the temperature calculating means 15 for sequentially updating the estimated temperature data from the memory 12 by calculating the current temperature of the billet, the target temperature curve corresponding to the material of the billet, etc. In the control band using Target temperature curve indexing means 16 for indexing the target temperature of the billet, optimum furnace temperature calculation method determining means 17 for determining the calculation method of the optimum furnace temperature set value according to the distribution state of the target temperature of the billet, and here The optimum furnace temperature set value calculation means 21 for calculating the optimum furnace temperature set value in the control zone in accordance with the optimum furnace temperature calculation method determined in.

In this embodiment, the optimum furnace temperature calculation method determining means 17 comprises a data editing section 18, a knowledge storage section 19, and an inference section 20. In the data editing unit 18, the position data of the billet in the heating furnace calculated by the position calculation unit 14 and the memory are stored.
Current temperature, size, material, surface temperature limit value, etc. of the billet stored in memory 12, target temperature data in the heating furnace of the billet indexed by the target temperature curve indexing means 16, and extraction pitch calculation The extracted pitch data and the like calculated by the means 13 are concentrated and sent to the inference unit 20 and also sent to the optimum furnace temperature set value calculation means 21. The inference unit 20 infers, based on these edited data and rules stored in advance in the knowledge storage unit 19, which of the optimum steel bills should be noted for calculating the furnace temperature set value. Determining the optimum furnace temperature set value and the optimum weighting coefficient used when calculating the optimum furnace temperature set value.

As an example, the rule group stored in the knowledge storage unit 19 is a first rule for inferring which is an optimum steel piece to be noted for calculating the furnace temperature set value. And a second rule for deciding an optimum furnace temperature set value calculation method and a third rule for deciding an optimum weighting coefficient used when calculating the optimum furnace temperature set value.

A specific example of each rule constituting the rule group will be described. Note that ∧ is a logical expression symbol indicating an AND (logical product) condition.

(1) Example of the first rule Example 1: (A steel billet whose material temperature is considerably lower than the target temperature is inserted in the control zone inlet) ∧ (The material temperature of the preceding material is close to the target temperature) ∧ (Same control There is no temperature-limiting material in the strip.) → (Furthermore, the furnace temperature setting device is calculated by paying attention to the charging material.) Example 2: (All steel pieces in the same control zone are near their target temperatures. ∧ (There is no temperature limiting material in the same control zone) → (Focus on the steel piece S ₁ on the extraction port side to calculate the furnace temperature set value) Example 3: (Same control zone The material temperature of the ingots in the furnace is lower than the target temperature of each ingot. ∧ (There is no temperature limiting material in the same control zone) → (All ingots in the same control zone (2) Example of second rule Example 1: (Calculate furnace temperature set value by paying attention to charging material) → (Reactor temperature set value calculation method (3 Selecting) Example 2: (focusing on slab S ₁ of the extraction port side to calculate the furnace temperature set value) → (furnace temperature setpoint calculation methods (1) to select a) Example 3: (same control zone Calculate the furnace temperature set value by paying attention to all the steel bills in the furnace) → (Select the furnace temperature set value calculation method (2)) (3) Example of the third rule Example 1: ( The furnace temperature set value calculation method (2) is selected) ∧ (The material temperature of the steel piece on the extraction port side is lower than the target temperature) → (Select the optimum weighting coefficient calculation method (b)) Example 2 : (Furnace temperature set value calculation method (2) is selected) ∧ (All steel slabs in the same control zone are insufficiently burnt) → (Optimized weight coefficient calculation method (a) Select) Example 3: (Furnace temperature set value calculation method (2) is selected) ∧ (Some slabs in the same control zone are underburned) → (Optimal weighting factor The calculation method (c) is selected) A signal representing the optimum furnace temperature set value calculation method and the optimum weight coefficient calculation method determined using such a rule is output to the optimum furnace temperature set value calculation means 21. .

In the optimum furnace temperature set value calculation means 21, based on the data edited by the data editing section 18, the optimum furnace temperature set value calculation method and the optimum weight coefficient calculation method determined by the inference section 20,
The furnace temperature set value most suitable for the finished state of the steel billet in the heating furnace is calculated. Based on the optimum furnace temperature set value calculated by the optimum furnace temperature set value calculation means 21, the furnace temperature of the continuous heating furnace 24 is controlled by the furnace temperature control means 4.

Next, the operation of the apparatus shown in FIG. 1 will be described.

The continuous heating furnace 2 heats the steel pieces successively inserted from the insertion port in different modes in the pre-tropical zone, the heating zone and the soaking zone, and extracts the heated steel pieces by the billet extracting means 3. Extract sequentially from the mouth. At this time, the furnace temperature in the soaking zone is detected by the furnace temperature sensor 5, and when the furnace temperature setting device 10 calculates and sets the optimum furnace temperature based on the detected value, the furnace temperature control means 4 follows the furnace temperature set value. Independently control furnace temperature.

Here, in order to set the furnace temperature, by inputting the material data such as the dimension of the billet, the material and the surface temperature limit value, the type of the process, the extraction target temperature, the process time such as the required time, by the input means 11, These data are stored in the memory 12. Further, every time a steel slab is extracted from the continuous heating furnace 2, an extraction signal is applied to the extraction pitch calculation means 13 and the temperature calculation means 15. The extraction pitch calculation means 13 calculates the extraction planned pitch until a certain time after, based on this extraction signal and the process data stored in the memory 12. Also, position calculation means
14 calculates the future position of the soaking zone of the steel slab at the scheduled extraction time obtained from this scheduled extraction pitch.

On the other hand, in the temperature calculation means 15, the extraction signal obtained from the continuous heating furnace 2 is received, and the detected value of the furnace temperature from the furnace temperature sensor 5 and the temperature calculation means 15 previously calculated and stored in the memory 12. The average temperature of the steel slab is calculated and estimated from the calculated average temperature of the steel slab, and the stored contents of the memory 12 are updated according to the result. Furthermore, in the target temperature curve indexing means 16, from the position within the soaking zone of the steel piece obtained from the position calculating means 14 and the material data of the steel piece obtained from the memory 12,
Index the target temperature of the billet. The optimum furnace temperature set value calculation method selection means 17 selects the calculation method of the furnace temperature set value for controlling the heating furnace according to what has been described above.

Next, in the optimum furnace temperature set value calculation means 21, the data editing unit 18
From the material data obtained from the data, the current estimated temperature data, the target temperature of the billet, and the position of the billet in the heating furnace,
According to the calculation method inferred in step 20, the furnace temperature set value most suitable for the burned state of the billet present in the control zone is calculated.

The furnace temperature control means 4 controls the furnace temperature of the continuous heating furnace 2 based on the furnace temperature set value calculated in this way.

Thus, according to the present embodiment, even if the burning state of the steel pieces mixed in the soaking zone changes, fine-grained control becomes possible, and when each steel piece is extracted, the steel The furnace temperature can be accurately set so as to keep the deviation between the extraction temperature of the piece and the extraction target temperature to a minimum.

In the above example, the furnace temperature setting device for controlling the furnace temperature in the soaking zone was described in particular, but the movement of the steel billet from the preheating zone to the heating zone, the movement of the billet from the heating zone to the soaking zone The present invention can also be applied to the temperature control of the pre-tropical zone or the heating zone by considering the above as extraction of steel slabs from the pre-tropical zone and heating zone, respectively.

〔The invention's effect〕

As is clear from the above description, according to the present invention,
Calculate the furnace temperature set value by accurately determining in a short time the burning state of the steel slab existing in the heating furnace from the material data, process data, and data such as surface temperature estimated value and material temperature estimated value. Infer the optimal billet for attention,
Based on this inference result, it is possible to calculate the optimum furnace temperature setting value, which enables highly accurate temperature control without overburning or underburning even when billets with different burning conditions are mixed in the furnace. Can be achieved. Further, according to the present invention, it is possible to eliminate the variation in the furnace temperature set value by the heating furnace operator and to contribute to the uniformity of the quality of the billet.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 to 5 are diagrams showing the relationship between the position of the steel slab and the temperature in order to explain the principle of the embodiment. 10 …… furnace temperature setting device, 11 …… input means, 12 …… memory,
13 ... Extraction pitch calculation means, 14 ... Position calculation means, 15 ...
… Temperature calculation means, 16 …… Target temperature curve indexing means, 17 ……
Optimal furnace temperature calculation method determining means, 18 ... Data editing section, 19 ...
… Knowledge storage section, 20 …… Inference section, 21 …… Optimum furnace temperature set value calculation means.

Claims (1)

[Claims] 1. A furnace temperature setting device for a continuous heating furnace, which individually sets an optimum furnace temperature of each control zone in order to individually control each furnace temperature of a plurality of control zones through which pieces of material to be heated continuously pass. In, the material data specific to the material to be heated, the process data specific to the process,
And a memory for storing the estimated temperature data of the piece of material to be heated obtained as a result of past calculation, and the piece of material to be heated in the furnace is extracted from the continuous heating furnace based on the process data stored in this memory. And a second calculating means for calculating the future extraction position of the material to be heated in the furnace at the expected extraction time calculated from the expected extraction pitch calculated by the first calculating means. Of the heating means of each control zone and the estimated temperature data stored in the memory, the present temperature of the piece of material to be heated is estimated, and the estimated temperature data in the memory is sequentially updated. The calculation means and the target temperature at each position in the furnace of the heated material piece are stored as a target temperature curve, and the future position of the heated material piece calculated by the second calculating means and the material stored in the memory Based on the data and process data, the target temperature curve indexing means for indexing the target temperature of each piece of the heated material at each position in the furnace, and the most suitable piece of heated material for calculating the furnace temperature set value are deduced and optimized. A knowledge storage unit that stores rules for determining a method for calculating the set value of the furnace temperature and an optimum weighting coefficient used when calculating the optimum set value of the furnace temperature, material data stored in the memory, A scheduled extraction pitch of the heated material piece calculated by the calculating means, second
Inside the furnace of the piece of material to be heated calculated by the calculating means, the current temperature of the piece of material to be heated calculated by the third calculating means, and the inside of the furnace of the piece of heated material indexed by the target temperature curve indexing means Based on the target temperature at each position and the rules stored in the knowledge storage unit, the most suitable material piece to be heated for calculating the furnace temperature set value is deduced, and the optimum furnace temperature set value is calculated. And an optimum weighting coefficient used to calculate the optimum furnace temperature set value, an inference section, each data used for inference by this inference section, and an optimum furnace temperature setting inferred by the inference section Based on the value calculation method and the optimum weighting coefficient, the furnace temperature set value is calculated so that each material temperature is secured at the extraction target temperature when the material piece to be heated is extracted from the continuous heating furnace. And a calculation means That the continuous heating furnace of a furnace temperature setting device.