JP2012140662A - Furnace temperature setting method for continuous heating furnace, furnace temperature control system, continuous heating furnace, and method for producing metal material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a furnace temperature setting method for a continuous heating furnace, capable of effectively reducing fuel consumption, a furnace temperature control system, a continuous heating furnace, and a method for producing a metal material.SOLUTION: The furnace temperature setting method for a continuous heating furnace includes renewing a set temperature of at least one combustion zone for each predetermined control cycle. An influence coefficient for evaluating an influence of a furnace temperature change of each combustion zone on the overall fuel usage of the heating furnace is calculated by a heat balance equation, an evaluation function with a furnace temperature change quantity of each combustion zone as a variable is constituted by use of the influence coefficient, a restriction condition on furnace temperature change quantity is determined, a furnace temperature change quantity of each combustion zone which optimizes the evaluation function under the restriction condition is determined, and the set temperature of each combustion zone is renewed based on the determined furnace temperature change quantity. The furnace temperature control system sets a furnace temperature by the furnace temperature setting method, the continuous heating furnace is provided with the furnace temperature control system, and the method for producing a metal material includes the step of heating the metal material by the continuous heating furnace.

Description

  The present invention relates to a furnace temperature setting method and furnace temperature control system for a continuous heating furnace, a continuous heating furnace, and a method for producing a metal material.

  The steel material is manufactured from iron ore by refining and casting, and then hot-rolled to make it thin or to form a hollow tube or the like. The steel material is brought to a set target extraction temperature by heating in a heating furnace (hereinafter sometimes referred to as “furnace”) before the hot rolling. The target extraction temperature is determined by the properties required for a product manufactured from the steel material because the properties of the steel differ depending on the difference in steel material temperature during hot rolling. Moreover, a target extraction soaking degree may be set. The target extraction soaking degree is set to prevent the steel material from being deformed after hot rolling because the properties of the steel differ depending on the portion of the steel material when a temperature difference occurs in the same steel material.

  In general, when heating a slab in a continuous heating furnace for hot rolling, the slab temperature seems to rise to the target extraction temperature set for each slab when extracting the slab from the furnace. Set the furnace temperature of each combustion zone in the operation.

  In setting the furnace temperature of each combustion zone, not only satisfying the target extraction temperature above, but also reducing the temperature difference between the slab surface and the inside of the slab (ensuring soaking), shortening the heating time, fuel consumption In many cases, consideration is given to the reduction of the above. As a technique related to a furnace temperature setting method for reducing the amount of fuel used, for example, Patent Document 1 discloses a temperature control method for determining an in-furnace temperature change amount that optimizes an evaluation function. As a quadratic function of the set furnace temperature and the set furnace temperature change amount of each combustion zone having a difference term between the extraction temperature and the predicted extraction temperature and a fuel consumption term, It is described that operation is performed with a focus on reducing fuel consumption by selecting a weighting factor.

  Further, in Patent Document 2, when a target temperature increase curve for each group of slabs is determined and the set furnace temperature is determined so as to satisfy the curve, the material at the time of starting maturation in order to ensure the soaking degree A technique is disclosed in which when there is a material whose predicted temperature value exceeds the value of the target temperature rise curve, dead heat is prevented by correcting the temperature rise rate in the combustion zone where the ripe heat starts.

Japanese Patent No. 2581832 Japanese Patent No. 2635240

  However, in the method described in Patent Document 1, the relationship between the furnace temperature and the fuel flow rate that should change according to the slab status of each combustion zone is not quantitatively evaluated. For this reason, it has been difficult to optimize fuel consumption.

  Further, in the method described in Patent Document 2, there is a weak basis that it is appropriate to correct the temperature of the ripening start zone as described above when considering the fuel consumption. That is, the achievement of energy saving is only qualitative, and it is difficult to say that fuel consumption is effectively reduced.

  Therefore, in view of the above circumstances, the present invention provides a furnace temperature setting method and furnace temperature control system for a continuous heating furnace, a continuous heating furnace, and production of a metal material that can effectively reduce fuel consumption. It is an object to provide a method.

  A first aspect of the present invention is a furnace temperature setting method for a continuous heating furnace in which a set temperature of at least one combustion zone is updated every predetermined control cycle, and the heat in each combustion zone in which the set temperature is updated is updated. An influence coefficient calculation step for calculating the influence coefficient for evaluating the influence of the furnace temperature change in each combustion zone on the fuel consumption of the whole continuous heating furnace using the heat balance equation indicating the input and output, and the influence coefficient And an evaluation function constituting step that constitutes an evaluation function with the furnace temperature change amount of each combustion zone as a variable, a constraint condition determining step that determines a constraint condition imposed on the furnace temperature change amount of each combustion zone, and a constraint condition The furnace temperature change amount of each combustion zone that optimizes the evaluation function is calculated and set as a set furnace temperature change amount, and a set furnace temperature change amount determining step, and according to the set furnace temperature change amount, A set temperature update process for updating the set temperature. To a furnace temperature setting method of a continuous heating furnace.

  Here, in the present invention, the “heat balance equation” means an equation describing the relationship between the amount of heat flowing into each combustion zone and the amount of heat flowing out from each combustion zone based on heat transfer engineering. Further, “heat” is not only an aspect of entering and exiting each combustion zone as thermal energy, but also an aspect of entering into each combustion zone as energy other than thermal energy and being converted into thermal energy in each combustion zone The concept also includes For example, although it is chemical energy when it flows into each combustion zone, the chemical energy of the fuel that is converted into thermal energy by a combustion reaction in each combustion zone is also included in the “heat” here.

  In the first aspect of the present invention, it is preferable that the evaluation function is a function representing a predicted amount of fuel consumption associated with a change in furnace temperature in the combustion zone.

  Here, in the present invention, the evaluation function is “a function representing the predicted amount of fuel consumption accompanying the change in the furnace temperature in the combustion zone”. The evaluation function is the fuel consumption accompanying the change in the furnace temperature in the combustion zone. It means that it consists of a term representing the predicted value of and a constant term. The constant term included in the evaluation function may be zero.

  In the first aspect of the present invention, the evaluation function configured in the evaluation function configuration step is linear, all the constraint conditions determined in the constraint condition determination step are linear, and in the set furnace temperature change amount determination step, It is preferable to calculate the amount of change in the furnace temperature of each combustion zone that optimizes the evaluation function by linear programming.

  Here, “all constraints are linear” means that all constraints are described by equations and / or inequalities of linear functions.

  According to a second aspect of the present invention, the furnace temperature of the continuous heating furnace is characterized in that the furnace temperature of the combustion zone is set by the furnace temperature setting method for the continuous heating furnace according to the first aspect of the present invention. Control system.

  According to a third aspect of the present invention, there is provided a continuous heating furnace including the furnace temperature control system for the continuous heating furnace according to the second aspect of the present invention.

  According to a fourth aspect of the present invention, there is provided a method for producing a metal material, comprising the step of heating the metal material using the continuous heating furnace according to the third aspect of the present invention.

  According to the furnace temperature setting method for a continuous heating furnace according to the first aspect of the present invention, since the heat input and output in each combustion zone is quantitatively considered using the heat balance equation, the fuel consumption is reduced. The furnace temperature can be set in the continuous heating furnace while effectively reducing the temperature.

  In the first aspect of the present invention, the evaluation function configured in the evaluation function configuration step is a function that represents a predicted amount of fuel consumption accompanying a furnace temperature change in the combustion zone, so that the fuel consumption is quantitatively determined. Since it can optimize after evaluating, the furnace temperature setting in a continuous heating furnace can be performed, reducing fuel consumption more effectively.

  In the first aspect of the present invention, the evaluation function configured in the evaluation function configuration step is linear, the constraint condition determined in the constraint condition determination step is linear, and in the set furnace temperature change amount determination step, the evaluation function By calculating the furnace temperature change of each combustion zone using the linear programming method, it is possible to easily optimize the evaluation function using a computer, thus saving computer resources and thus reducing costs. Become.

  According to the furnace temperature control system for the continuous heating furnace according to the second aspect of the present invention, the furnace temperature setting method for the continuous heating furnace is the furnace temperature setting method for the continuous heating furnace according to the first aspect of the present invention. Is done by. As described above, the furnace temperature setting method for the continuous heating furnace according to the first aspect of the present invention can effectively reduce fuel consumption. Therefore, according to the 2nd aspect of this invention, the furnace temperature control system of a continuous heating furnace which can reduce fuel consumption effectively can be provided.

  The continuous heating furnace which concerns on the 3rd aspect of this invention is equipped with the furnace temperature control system of the continuous heating furnace which concerns on the 2nd aspect of this invention. As described above, according to the furnace temperature control system of the continuous heating furnace according to the second aspect of the present invention, the furnace temperature can be set while effectively reducing the fuel consumption. Therefore, according to the 3rd aspect of this invention, the continuous heating furnace which can reduce fuel consumption effectively can be provided.

  According to the method for producing a metal material according to the fourth aspect of the present invention, the metal material is heated using the continuous heating furnace according to the third aspect of the present invention. As described above, the continuous heating furnace according to the third aspect of the present invention can effectively reduce fuel consumption. Therefore, according to the 4th aspect of this invention, the manufacturing method of a metal material which can reduce fuel cost effectively can be provided.

It is a flowchart explaining the furnace temperature setting method of the continuous heating furnace of this invention. It is a schematic diagram of a continuous heating furnace. It is a figure explaining the heat input / output of each combustion zone. It is a figure explaining the furnace temperature control system of the continuous heating furnace of this invention. It is a figure explaining the continuous heating furnace of this invention. It is a flowchart explaining the manufacturing method of the metal material of this invention. It is a figure which shows transition of the prediction furnace temperature in the example of an invention. It is a figure which shows transition of the predicted fuel consumption in the example of an invention. It is a figure which shows transition of the prediction furnace temperature in a comparative example (conventional method). It is a figure which shows transition of the predicted fuel consumption in a comparative example (conventional method).

  The above-mentioned operation and gain of the present invention will be clarified from embodiments for carrying out the invention described below. Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the form shown below is an illustration of this invention and this invention is not limited to these forms.

<1. How to set the furnace temperature of a continuous heating furnace>
The furnace temperature setting method of the continuous heating furnace of the present invention will be described. FIG. 1 is a flowchart for explaining a furnace temperature setting method S10 (hereinafter sometimes referred to as “furnace temperature setting method S10” or simply “S10”) for a continuous heating furnace. FIG. 2 is a schematic diagram showing the continuous heating furnace 10 to which S10 is applied. FIG. 3 is a view for explaining heat input and output for one combustion zone of the continuous heating furnace 10.
Hereinafter, the furnace temperature setting method of the continuous heating furnace of the present invention will be described with reference to FIGS.

As shown in FIG. 2, in the continuous heating furnace 10, the inside and outside of the furnace are separated by the furnace wall 1. The space in the furnace is further divided into a pre-tropical zone 2, a first heating zone 3, a second heating zone 4, and a soaking zone 5 by the furnace wall 1, and these four combustion zones are arranged in this order from the left side of the page. Lined up to the right. The above four combustion zones are provided with skids 6, and the slabs 9, 9,... Inserted from the slab inlet 7 move in the respective combustion zones on the skid 6 in order from the pre-tropical zone 2, and are desired. Is finally taken out from the slab extraction port 8.
In the furnace temperature setting method of the present invention, in a continuous heating furnace having a plurality of combustion zones as shown in FIG. 2, extraction is performed after heating a plurality of slabs in each combustion zone to a target extraction temperature set for each slab. In doing so, the furnace temperature setting model is activated for each specific control period, and the set temperature of each combustion zone is updated.

  As shown in FIG. 1, the furnace temperature setting method S10 for the continuous heating furnace includes an influence coefficient calculation step S11, an evaluation function configuration step S12, a constraint condition determination step S13, a set furnace temperature change amount determination step S14, And a set temperature update step S15.

The influence coefficient calculation step S11 (hereinafter, sometimes simply referred to as “S11”) uses a heat balance equation indicating heat input and output in each combustion zone, and changes in the furnace temperature in each combustion zone are the same for the entire continuous heating furnace. This is a step of calculating an influence coefficient for evaluating the influence on the fuel consumption. Details will be described below. In the following, when “X = (x ¹ ,... X ^N )” is expressed for a certain vector X, it means that X is an Nth-order horizontal vector, and “Y = (y ¹ ,... Y ^N ) ^T ”means that Y is an Nth-order vertical vector. A superscript T on the right side of the vector Y is a symbol representing transposition. In addition, unless otherwise specified, a simple expression “vector” means a vertical vector.

  In the furnace temperature setting model, the set furnace temperature vector for each combustion zone

To decide. Equation (1) represents a z _{N -th} order vertical vector. Each component represents the in-furnace gas temperature of each combustion zone, and its unit is [° C.]. The superscript z of each component represents a combustion zone. z _N represents the total number of the combustion zone to try to furnace temperature setting. For example, z _N = 3 when setting the first heating zone, the second heating zone, and the soaking zone furnace temperature. The superscript z is assigned in order from the combustion zone closer to the charging furnace inlet.

  Formulate the heat balance equation for each combustion zone. In each combustion zone, it is considered that heat is input and output as shown in FIG. 3. Therefore, considering the heat balance in each combustion zone and the time differentiation of the gas temperature in the furnace, the heat balance equation for the combustion zone z is It is expressed as

In the formula (2), c _gas is the furnace specific gas heat [kcal / Nm ³ · ° C.]. V _f ^z is the furnace volume [m ³ ] of the combustion zone z. Hl is the combustion calorific value [kcal / Nm ³ ] of the fuel. v ^z _fuel (T ^z _f ) is the fuel inflow amount [Nm ³ / hr] in the combustion zone z. q _air (T ^z _f ) is the amount of heat [kcal / Nm ³ ] of the combustion air per fuel unit. q _gas (T ^z _f ) is the amount of heat [kcal / Nm ³ ] of the gas in the furnace in the combustion zone z that is discharged from the combustion zone z to the outside of the furnace per fuel unit. Q ^z _next is an amount of heat (adjacent radiant heat) [kcal / hr] flowing out from the combustion zone z to the adjacent combustion zone. Note that in the Q ^z _next, when the superscript z is 1, a combustion zone z-1 is not considered, when z is z _N, the combustion zone z + 1 is not considered . Q ^z _slab is the amount of heat (slab sensible heat) [kcal / hr] used for heating the slab existing in the combustion zone z. Slab temperature vector

Is a vertical vector whose component is the temperature [° C.] of each slab present in the combustion zone z, and N _z is the total number of slabs present in the combustion zone z. Q ^z _body is the amount of heat (furnace body heat dissipation) [kcal / hr] dissipated to the environment from the combustion zone z portion of the heating furnace body. Q ^z _skid is the amount of heat (skid loss heat) [kcal / hr] absorbed by the cooling water flowing in the skid existing in the combustion zone z. Q ^z _open is the amount of heat (opening radiant heat) [kcal / hr] radiated to the environment from the heating furnace opening of the combustion zone z.

Hlv ^z _fuel (T ^z _f ) is a calorific value (fuel combustion heat) [kcal / hr] due to fuel combustion. q ^z _air (T ^z _f ) v ^z _fuel (T ^z _f ) is the amount of heat (preliminary sensible heat) [kcal / hr] that the preheated combustion air brings into the combustion zone z. q ^z _gas (T ^z _f ) v ^z _fuel (T ^z _f ) is the amount of heat (exhaust gas sensible heat) [kcal / hr] that the in-furnace gas discharged from the combustion zone z takes away from the combustion zone z.

In addition, since there is no means for measuring the temperature of each slab in formula (3) in the heating furnace, the temperature measured before charging the heating furnace is set as an initial value, and the temperature is determined by accumulating the slab sensible heat Q _{slab at} each time. Use the calculated value considered to have risen.

When equation (2) is solved for v ^z _fuel , a fuel flow rate calculation equation (4) for each time with the furnace temperature as an input is obtained.

Using the fuel flow rate calculation formula of Formula (4), with the furnace temperature at the furnace temperature setting model start time t ₀ as the initial value, the entire heating furnace when operating with the set furnace temperature vector for the time t ₁ The predicted fuel usage U ⁰ _fuel at is calculated by the following equation (5). t ₁ is preferably 3 minutes or more and 60 minutes or less, for example, 30 minutes. By setting t ₁ to 3 minutes or more, it becomes easy to ensure the difference between the predicted fuel usage and the U ⁰ _fuel when the furnace temperature is changed in one heating furnace. Further, by the t ₁ and 60 minutes or less, since the amount of calculation is reduced, it becomes easier to reduce the cost by saving computer resources. In addition, in the calculation of the influence coefficient by the equation (7) described later, it becomes easy to obtain a better approximate value of the partial differential coefficient on the left side.

Furthermore, the predicted fuel usage when the furnace temperature is changed from T ^zi _f by δT ^zi _{f in} a certain combustion zone z _{i and the} operation is performed only for time t ₁ can be calculated by the following equation.

The calculation of Equation (6) is performed for all combustion zones for which influence coefficients are to be calculated, that is, z _N combustion zones for which the furnace temperature is set. In the calculation of the above formula (6), δT ^zi _f is preferably 5 ° C. or more and 50 ° C. or less, and can be set to 20 ° C., for example. By setting δT ^zi _f to 5 ° C. or more, it becomes easy to ensure the difference between U ^zi _fuel and U ⁰ _fuel . Further, by setting δT ^zi _f to 50 ° C. or less, it becomes easy to obtain a better approximate value of the partial differential coefficient on the left side in the calculation of equation (7) described later.

The influence coefficient for evaluating the influence of the change in the furnace temperature of the combustion zone z _{i on} the fuel consumption amount U _fuel of the entire heating furnace is expressed by the partial differential coefficient ∂ U _fuel / ∂ T ^zi _f , and the furnace is expressed by the equation (6). The difference between the predicted fuel usage when the temperature is changed and the predicted fuel usage when there is no furnace temperature change in Equation (5) can be approximated by a value divided by the furnace temperature change amount δT ^zi _f . Therefore, it calculates with the following formula | equation (7).

  By calculating the equation (7) for each combustion zone, an influence coefficient vector having an influence coefficient for each combustion zone as a component.

Ask for. Thus, the influence coefficient calculation step S11 is completed.

  In the evaluation function configuration step S12 (hereinafter, simply referred to as “S12”), the amount of change in the furnace temperature of each combustion zone from the set furnace temperature vector of Equation (1) is calculated using the influence coefficient obtained in S11. Furnace temperature change vector for components

Is a step of constructing an evaluation function J with 変 数 as a variable. The evaluation function J is a predicted fuel consumption amount U _fuel , and is constituted by the product sum of the influence coefficient of each combustion zone and the furnace temperature change amount, using the influence coefficient obtained in S11 as a weighting coefficient. That is, using the inner product of the influence coefficient vector ∂ U _fuel / ∂T _f of Equation (8) and the furnace temperature change vector ΔT _{f of} Equation (9), the following equation is used.

The evaluation function J in the equation (10) is a function of the furnace temperature change amount vector ΔT _f and directly evaluates the predicted amount U _fuel of the combustion consumption. Therefore, by optimizing the evaluation function J of the equation (10) with respect to the furnace temperature change vector ΔT _f in the set furnace temperature change amount determination step S14 described later, the furnace temperature setting method S10 that can effectively reduce the fuel consumption. It becomes possible. Further, by configuring the evaluation function J as a linear function as shown in Expression (10), the set furnace temperature change amount can be determined by linear programming as described later.

The constraint condition determination step S13 (hereinafter sometimes simply referred to as “S13”) is a step of determining a constraint condition imposed on the furnace temperature change amount of each combustion zone. The constraint condition is determined so as to form a feasible region with respect to the furnace temperature change vector ΔT _f of Equation (9). In S13, the constraint condition is defined as a line form represented by the general formula (11).

a _i is a constant vector and b _i is a constant. For example, the upper limit constraint on the furnace temperature is expressed by equation (12), and the lower limit constraint is expressed by equation (13). Moreover, the upper limit constraint of the set furnace temperature difference from the adjacent zone is expressed by Equation (14), and the lower limit constraint is expressed by Equation (15).

T ^z _{f, MAX} is the set furnace temperature upper limit of the combustion zone z. T ^z _{f, min} is a set furnace temperature lower limit of the combustion zone z. T ^z _{fnext, MAX} is the upper limit of the set furnace temperature difference from the adjacent combustion zone. T ^z _{fnext, min} is the lower limit of the set furnace temperature difference from the adjacent combustion zone. Expressions (12) to (15) are all linear.

The constraint condition also incorporates a condition (target extraction temperature condition) that the temperature at the time of extraction of each slab is equal to or higher than the target extraction temperature of each slab. Generally, since the furnace temperature change amount in each combustion zone and the temperature at the time of slab extraction are in a non-linear relationship, the condition cannot be expressed strictly in a linear form. However, in a certain slab slab _i , the predicted extraction temperature when operating until extraction with the furnace temperature of each combustion zone set to the set furnace temperature vector T _f of equation (1) is T ⁰ _{slab i, out} , in a certain combustion zone z If the predicted extraction temperature when the furnace temperature is changed from T ^z _f by δT ^z _f and the operation until the extraction is performed similarly is T ^z _{slabi, out} , the change rate of the extraction temperature with respect to the furnace temperature change in the combustion zone z, That is, the partial differential coefficient ∂T ^z _{slabi, out} / ∂T ^z _f can be approximated by the following equation.

By calculating the equation (16) for z _N combustion zones for setting the furnace temperature, the slab extraction temperature change coefficient vector ∂T ^z _{slab, out} / ∂T _f expressed by the equation (17) is obtained. Here, it is not necessary to make the value of δT ^z _f coincide with δT ^zi _f in the equation (6). δT ^z _f is preferably 5 ° C. or more and 50 ° C. or less, and can be, for example, 10 ° C. By setting δT ^z _f to 5 ° C. or more, it becomes easy to ensure the difference between T ^z _{slabi, out} and T ⁰ _{slabi, out} . Further, by setting δT ^z _f to 50 ° C. or less, it becomes easy to obtain a better approximate value of the partial differential coefficient on the left side in Equation (16).

By using the slab extraction temperature change coefficient vector of Expression (17), the predicted extraction temperature of the slab can be approximated in a linear form, and the conditional expression of the target extraction temperature condition can be expressed in the following linear form (18).

Determine the formula (12) to (15) and equation (18) as a constraint condition of furnace temperature variation vector [Delta] T _f, S13 is completed. Expressions (12) to (15) and Expression (18) are all linear, and the evaluation function J configured in S12 is also linear. Therefore, in the set furnace temperature change amount determination step S14, which is the next step, the evaluation function J can be optimized by the linear programming method under the constraint conditions determined in S13.

In the set furnace temperature change amount determination step S14 (hereinafter, also simply referred to as “S14”), the furnace temperature of each combustion zone that optimizes the evaluation function J configured in S12 under the constraint conditions determined in S13. This is a step of calculating the change amount and setting it as the set furnace temperature change amount. Specifically, a furnace temperature change vector ΔT _f from the set furnace temperature vector T _f that minimizes the evaluation function J while satisfying the above-mentioned constraint conditions is obtained, and this ΔT _f is set as the set furnace temperature change amount. Let it be a vector ΔT _{f, opt} .

As described above, since the equations (12) to (15) and (18) constituting the constraint conditions are all linear, and the evaluation function J configured in S12 is also linear, the optimization in S14 is linear programming. Can be done by. Therefore, it is possible to derive easily set oven temperature change amount vector [Delta] T _f. Therefore, since the amount of calculation can be reduced, it is possible to save computer resources and reduce operating costs. In the optimization, a known solution algorithm for a linear programming problem such as a simplex method or a car marker method (inner point method) can be used without particular limitation.

The set temperature update step S15 (hereinafter sometimes simply referred to as “S15”) is a step of updating the set temperature of each combustion zone in accordance with the set furnace temperature change amount derived in S14. That is, a new set furnace temperature vector T _{f, new} is calculated from the set furnace temperature vector T _f and the set furnace temperature change amount vector ΔT _{f, opt} by the following equation.

By applying the set furnace temperature value that the new set furnace temperature vector _{Tf, new} calculated by Equation (19) has as the component to each corresponding combustion zone, S15 ends.

  With the completion of S11 to S15, all the steps of the furnace temperature setting method S10 for the continuous heating furnace are completed. After the end of S15, S10 is executed every specific cycle (control cycle), and the set furnace temperature is repeatedly updated. The control period is preferably 3 minutes or more and 60 minutes or less, for example, 3 minutes. By setting the control period to 3 minutes or more, the amount of calculation is reduced, so it is easy to save computer resources and reduce costs. Further, by setting the control period to 60 minutes or less, finer furnace temperature control becomes possible, and it becomes easier to suppress the situation where the slab extraction temperature is lower than the target extraction temperature. In addition, since it becomes possible to flexibly cope with operating conditions that change from moment to moment, fuel consumption can be more effectively reduced.

  In the above description regarding the present invention, the influence coefficient calculation step S11, the evaluation function configuration step S12, the constraint condition determination step S13, the set furnace temperature change amount determination step S14, and the set temperature update step S15 are performed in this order. Although the furnace temperature setting method S10 of the continuous heating furnace has been exemplified, the present invention is not limited to this form. For example, the constraint condition determining step S13 may be performed prior to the influence coefficient calculating step 11.

  In the above description regarding the present invention, the furnace temperature setting method S10 of the continuous heating furnace in which the optimization of the evaluation function J is minimized has been exemplified, but the present invention is not limited to this form. For example, the evaluation function can be maximized by inverting the sign of the evaluation function.

  In the above description regarding the present invention, in the constraint condition determination step S13, the constraint conditions are the set furnace temperature upper and lower limits of each combustion zone, the set furnace temperature difference upper and lower limits of adjacent combustion zones of each combustion zone, and the target extraction temperature condition. Although the furnace temperature setting method S10 of the continuous heating furnace of a certain form was illustrated, this invention is not limited to the said form. For example, the lower limit of the set furnace temperature and the upper and lower limits of the set furnace temperature difference with the adjacent combustion zone may be in a form in which at least a part of these is not a constraint. Moreover, the form which also determines constraint conditions other than the above may be sufficient. As a constraint condition other than the above, for example, a condition that the target extraction soaking degree is satisfied can be exemplified.

In the above description regarding the present invention, the furnace temperature setting method S10 of the continuous heating furnace in which all the constraint conditions are in the linear form is exemplified, but the present invention is not limited to this form. It is also possible to adopt a form in which at least a part of the constraint condition is determined as a nonlinear expression. For example, it is possible to adopt a form in which the target extraction temperature condition is represented by a nonlinear expression without adopting the linear approximation formula (18) in the target extraction temperature condition. According to the form in which the linear approximation is not adopted in the target extraction temperature condition, it is not necessary to perform the calculation of Expression (16) several times for the slab in order to obtain the slab extraction temperature change coefficient vector ∂T ^z _{slab, out} / ∂T _f. . However, in general, the evaluation function J cannot be optimized by linear programming, which generally increases the amount of calculation. Therefore, strictly speaking, it is preferable to adopt a linear approximation to determine all the constraint conditions in a linear format even if there are constraint conditions represented by a non-linear expression.

  In the above description regarding the present invention, the furnace temperature setting method S10 of the continuous heating furnace in the form using the heat balance equation represented by the equation (2) is exemplified, but the present invention is not limited to this form. It is also possible to adopt a form using a heat balance equation including a term other than the term of equation (2). Examples of the term other than the term possessed by the formula (2) include a term for evaluating the heat in and out due to the movement of the in-furnace gas between the adjacent combustion zones. By further including such a term in the heat balance equation, the heat balance can be evaluated with higher accuracy, so that the fuel consumption can be predicted with higher accuracy. Therefore, it becomes easy to set it as the furnace temperature setting method of a continuous heating furnace which can reduce fuel consumption more effectively.

Further, in the above description regarding the present invention, the furnace temperature setting method of the continuous heating furnace in which the set furnace temperature is constantly updated for z _N combustion zones in all control cycles has been described. It is not limited to. It is also possible to adopt a form in which the combustion zone or the set of combustion zones in which the set furnace temperature is updated differs depending on the control cycle. For example, in a continuous heating furnace having four combustion zones, the set furnace temperature is updated for all four combustion zones in a certain control cycle, and the two combustions on the side closer to the slab extraction port in the next control cycle. It is also possible to update the set furnace temperature only for the belt. According to such a form, it is possible to reduce the amount of calculation. However, in order to satisfactorily exert the fuel consumption reduction effect of the present invention, the set furnace temperature is always updated for all combustion zones or all combustion zones other than the pre-tropical zone in all control cycles. It is preferable to do.

<2. Continuous heating furnace temperature control system>
FIG. 4 is a diagram illustrating a furnace temperature control system 20 (hereinafter, simply referred to as “furnace temperature control system 20”) of the continuous heating furnace of the present invention. The furnace temperature control system 20 is a system that sets and controls the furnace temperatures of the four combustion zones of the continuous heating furnace 10 (see FIG. 2) by the furnace temperature setting method S10. As shown in FIG. 4, the furnace temperature control system 20 includes a control unit 11, a storage unit 12, an input unit 13, an output unit 14, a furnace temperature measurement unit 15, and a pre-charging slab temperature measurement unit 16. The furnace temperature adjusting means 17 is connected. In FIG. 4, arrows indicate the direction in which information flows. Hereinafter, each component will be described in order.

  The control means 11 is a component that controls the entire furnace temperature control system 20. In the furnace temperature control system 20, regardless of input or output, all existing information is managed by the control means 11, processed, and transmitted to other components. As the control means 11, an electronic computer or other known control device can be used without particular limitation.

The storage unit 12 is a component that receives and stores all information in the furnace temperature control system 20 from the control unit 11 and outputs the information to the control unit 11 when requested by the control unit 11. The storage unit 12 stores an algorithm A1 (hereinafter referred to as “algorithm A1”) for executing the above-described furnace temperature setting method S10, and stores information necessary for executing S10. Information necessary for executing S10 includes all the parameters required for the calculation of the above-described set furnace temperature vector T _f , slab temperature vector T ^z _{slab and} other fuel flow rate calculation formula (4), and the influence coefficient vector ∂U. _fuel / ∂T _f , furnace temperature change vector ΔT _f , evaluation function J, slab extraction temperature change coefficient vector ∂T ^z _{slab, out} / ∂T _f , and constraint equation are included. As the storage means 12, a known storage device such as a magnetic storage device or a volatile memory (RAM) can be used without particular limitation.

  The input means 13 is a component for the operator and / or the host computer to input necessary information other than the current furnace temperature and pre-charging slab temperature in the furnace temperature control system 20. Information input from the input means 13 is transmitted to the control device 11 and stored in the storage means 12. As the input means 13, a known input device such as a keyboard or a known communication device such as a serial port can be used without particular limitation.

  In the furnace temperature control system 20, the output unit 14 is a component for receiving information to be known by the operator and / or the host computer from the control unit 11 and displaying the information to the operator or the host computer. The output means 14 displays or outputs the set furnace temperature, current furnace temperature, slab temperature, slab heating status, fuel flow rate, air flow rate and other necessary information. For the output means 14, a known display device such as a display or a known communication device such as a serial port can be used without particular limitation.

  The furnace temperature measuring means 15 is a component that measures the furnace temperature of each combustion zone. As shown in FIG. 4, the furnace temperature measuring means 15 has furnace temperature sensors 15a, 15b, 15c, and 15d (hereinafter, sometimes referred to as “furnace temperature sensors 15a to 15d”), and these four furnace temperatures. One sensor is installed in each combustion zone. The furnace temperature information acquired by the furnace temperature measuring unit 15 is transmitted to the control unit 11 and stored in the storage unit 12. As the furnace temperature sensors 15a to 15d, a known temperature sensor suitable for measurement in a high temperature region such as a thermocouple or a radiation thermometer can be used without particular limitation.

  The pre-charging slab temperature measuring means 16 is a component that measures the temperature of each slab before charging into the continuous heating furnace 10. The temperature information of the slab before charging acquired by the slab temperature measuring means 16 before charging is transmitted to the control means 11 and stored in the storage means 12. A known temperature sensor such as a thermocouple or a radiation thermometer can be used as the pre-loading slab temperature measuring means 16 without any particular limitation.

  The furnace temperature adjusting means 17 is connected to burners 21a, 21b, 21c, and 21d (hereinafter, sometimes referred to as “burners 21a to 21d”) that are burners in each combustion zone. The furnace temperature adjusting means 17 is a component that adjusts each combustion amount of the burners 21 a to 21 d in accordance with the set furnace temperature determined by the control device 11. The furnace temperature adjusting means 17 acquires the set furnace temperature of each combustion zone and the current actual furnace temperature from the control device 11, and adjusts each combustion amount of the burners 21a to 21d so that the actual furnace temperature becomes the set furnace temperature. To do. The amount of burner combustion is adjusted by adjusting the flow rates of fuel and combustion air supplied to each burner. As the furnace temperature adjusting means 17, a known furnace temperature adjusting means having the above function can be used without any particular limitation.

  Hereinafter, the operation of the furnace temperature control system 20 will be described.

(A. Information input)
The operator and / or the host computer inputs the target extraction temperature of the slab and other information necessary for setting the furnace temperature by the furnace temperature setting method S10 through the input means 13. The control unit 11 acquires the input information and stores it in the storage unit 12.

(B. Operation: Slab heating)
The operator and / or the host computer instructs the control device 11 to start updating the set furnace temperature through the input means 13. The control device 11 acquires the temperature information before charging each slab by the slab temperature measuring means 16 before charging and stores it in the storage means 12. The control device 11 reads and executes the algorithm A1 from the storage means 12, and repeats the update of the set furnace temperature by the furnace temperature setting method S10 every control cycle of 3 minutes.

  Each time the set furnace temperature is updated, the control device 11 transmits to the furnace temperature adjusting means 17 the new set furnace temperature and the current furnace temperature of each combustion zone. The furnace temperature adjusting means 17 updates the furnace temperature by adjusting the burner combustion in each combustion zone while constantly receiving and monitoring the actual furnace temperature information from the control device 11 based on the newly set furnace temperature. Change to the set furnace temperature. When the furnace temperature reaches the updated set furnace temperature, the furnace temperature adjusting means 17 maintains the set furnace temperature until the next updated set furnace temperature is transmitted from the control device 11.

  In the above description regarding the present invention, the furnace temperature control system 20 in the form of controlling the furnace temperatures of the four combustion zones has been exemplified, but the present invention is not limited to this form. In accordance with the form of the continuous heating furnace to be controlled, it is possible to control the furnace temperature of less than four, or five or more combustion zones.

<3. Continuous heating furnace>
FIG. 5 is a diagram illustrating the continuous heating furnace 30 of the present invention. The continuous heating furnace 30 is a continuous heating furnace including the furnace temperature control system 20 described above. As shown in FIG. 5, the continuous heating furnace 30 has a pre-tropical zone 2, a first heating zone 3, a second heating zone 4, and a soaking zone 5 separated from the outside of the furnace by the furnace wall 1. And a skid 6, a slab loading port 7, and a slab extraction port 8. The pre-tropical zone 2, the first heating zone 3, the second heating zone 4, and the soaking zone 5 are arranged in this order from the slab loading inlet 7 side to the slab extraction port 8 side. The skid 6 exists in each combustion zone from the slab loading inlet 7 to the slab extraction opening 8, and the slabs 9, 9,... Move on the skid 6 from the slab loading inlet 7 to the slab extraction opening 8. A cooling water passage (not shown) is provided in a portion of the skid 6 inside the combustion zone, and the cooling water is circulated by a pump (not shown). Each combustion zone is provided with one burner 21a, 21b, 21c, 21d, and one furnace temperature sensor 15a-15d. Further, a slab temperature measuring means 16 before charging is disposed immediately before the slab inlet 7. Each of the burners 21a to 21d is connected to the furnace temperature adjusting means 17 (see FIG. 4) of the furnace temperature control system 20, and the supply flow rate of fuel and combustion air to each burner is adjusted by the furnace temperature adjusting means 17. The In FIG. 5, the furnace temperature sensors 15 a to 15 d and the pre-charging slab temperature measuring means 16 are a part of the furnace temperature control system 20.

  As the burners 21a to 21d, known burners such as a continuous heating burner and a regenerative switching burner can be used without particular limitation. However, it is preferable to use a heat storage type switching burner from the viewpoint of being able to respond flexibly to changes in the set temperature.

  In the continuous heating furnace 30, the slab temperature information immediately before being charged is measured by the pre-charging slab temperature measuring means 16. Moreover, the furnace temperature information of each combustion zone is acquired by the furnace temperature sensors 15a to 15d. These pieces of information are processed by the furnace temperature control system 20, and the furnace temperature is set by the furnace temperature control system 20. The set furnace temperature is reflected on the actual furnace temperature by the control of the burners 21 a to 21 d by the furnace temperature control system 20. The furnace temperature control system 20 repeats the update of the set furnace temperature every predetermined control cycle, and each time the set furnace temperature is updated, the updated set furnace temperature is reflected on the actual furnace temperature. Since the setting of the furnace temperature and the adjustment of the furnace temperature by the furnace temperature control system 20 have already been described, the description thereof will be omitted.

  In the above description related to the present invention, the continuous heating furnace 30 having four combustion zones has been illustrated, but the present invention is not limited to this form. It is also possible to have a configuration having less than four, or five or more combustion zones.

  In the above description related to the present invention, the continuous heating furnace 30 in which one burner is provided for each combustion zone has been exemplified, but the present invention is not limited to this form. It is also possible to have a combustion zone having a plurality of burners in one combustion zone. According to such a form, it is preferable because not only the thermal power is increased but also it is easy to reduce the temperature unevenness in the combustion zone. Furthermore, all the burners can be individually controlled by the furnace temperature control system 20. According to such a form, more detailed control is easy about the furnace temperature and temperature distribution of each combustion zone, and it is preferable.

  In the above description related to the present invention, the continuous heating furnace 30 in which one furnace temperature measuring means is provided for each combustion zone is exemplified, but the present invention is not limited to this form. It is also possible to adopt a form having a combustion zone provided with a plurality of furnace temperature measuring means in one combustion zone. According to such a configuration, the temperature can be monitored not only in one place but also in a plurality of places inside the combustion zone, and therefore, detailed control of the furnace temperature and temperature distribution in each combustion zone is facilitated, which is preferable. .

  Moreover, in the said description regarding this invention, although the continuous heating furnace 30 of the form which controls the furnace temperature of all the combustion zones by the furnace temperature control system 20 was illustrated, this invention is not limited to the said form. The continuous heating furnace of the present invention only needs to control at least one combustion zone based on the furnace temperature setting method of the present invention, and has a form having a combustion zone that is not controlled by the furnace temperature control system 20. It is also possible to do. However, from the standpoint of maximizing the effect of reducing fuel consumption, a mode in which all combustion zones are controlled by the furnace temperature control system 20 or all combustion zones except the pre-tropical zone are controlled by the furnace temperature. It is preferable that the furnace temperature is controlled by the system 20.

<4. Manufacturing method of metal material>
The manufacturing method of the metal material of this invention is demonstrated. FIG. 6 is a flowchart for explaining a hot-rolled steel sheet manufacturing method S20 (hereinafter sometimes simply referred to as “S20”). In S20, after heating a slab using the above-mentioned continuous heating furnace 30 (refer FIG. 5), hot rolling is performed and a hot-rolled steel plate is manufactured. As shown in FIG. 6, S20 has slab preparation process S21, slab heating process S22, and hot rolling process S23 in this order. Hereinafter, it demonstrates in order.

  The slab preparation step S21 (hereinafter sometimes simply referred to as “S21”) is a step of preparing a slab to be hot-rolled in S20. S21 has the process of casting a slab, and the process of conveying the cast slab to the continuous heating furnace 10. FIG.

  The slab heating step S22 (hereinafter sometimes simply referred to as “S22”) is a step of heating the slab prepared in S21 to a target extraction temperature or higher by the continuous heating furnace 30. As shown in FIG. 5, the continuous heating furnace 30 has a total of four combustion zones: a pre-tropical zone 2, a first heating zone 3, a second heating zone 4, and a soaking zone 5. In the continuous heating furnace 30, the furnace temperature is controlled by the furnace temperature control system 20 by repeatedly updating the set furnace temperature in a control period of 3 minutes for all four combustion zones. In S22, the slab is charged into the continuous heating furnace 30 from the slab inlet 7, and passes through the pre-tropical zone 2, the first heating zone 3, the second heating zone 4 and the soaking zone 5 in this order, and is above the target extraction temperature. Heat to the temperature of. The heated slab is extracted from the slab extraction port 8.

  The hot rolling step S23 (hereinafter, sometimes simply referred to as “S23”) is a step of forming a hot-rolled steel sheet by performing hot rolling on the slab heated to the target extraction temperature in S22. In the hot rolling in S23, a known rolling device used for manufacturing a hot rolled steel sheet can be used without particular limitation.

  In the said description regarding the manufacturing method of the metallic material of this invention, although the form which manufactures a hot-rolled steel plate was illustrated, this invention is not limited to the said form. After hot rolling, it is possible to produce a cold rolled steel sheet by pickling and cold rolling. Moreover, it is also possible to set it as the form which manufactures a plated steel plate by performing a plating process further to a cold-rolled steel plate. Moreover, it is also possible to adjust the properties such as toughness to a desired range by performing temper rolling after cold rolling. Moreover, it is also possible to set it as the form provided with the surface treatment process which performs surface treatments, such as chemical treatment, to the said hot-rolled steel plate, cold-rolled steel plate, or plated steel plate.

  In the said description regarding the manufacturing method of the metal material of this invention, although the form which manufactures a steel plate was illustrated, this invention is not limited to the said form. The manufacturing method of the metallic material of the present invention only needs to have a step of heating the metallic material using the continuous heating furnace in which the furnace temperature is set by the furnace temperature setting method of the continuous heating furnace of the present invention. . For example, it is possible to adopt a form in which a steel pipe is manufactured.

  Moreover, in the said description regarding the manufacturing method of the metal material of this invention, although the form which processes steel was illustrated, this invention is not limited to the said form. The metal material is not limited to steel, and may be a metal material other than steel, such as a non-ferrous metal or an alloy. Even if it is a form which manufactures metal materials other than steel, a metal material can be manufactured, reducing fuel consumption effectively.

  Hereinafter, based on an Example, this invention is further explained in full detail.

  A simulation experiment was conducted on the furnace temperature setting method of the continuous heating furnace of the present invention. In the simulation experiment, a continuous heating furnace to which the furnace temperature setting method of the present invention is applied is a continuous heating furnace having a pre-tropical zone, a first heating zone, a second heating zone, and a soaking zone in this order from the slab loading side. Among the four combustion zones, the first heating zone, the second heating zone, and the soaking zone furnace temperature were set.

(Invention example)
It was assumed that the furnace temperature was unchanged during the control period. Pre-tropical furnace temperature was fixed at the value of actual heating. An influence coefficient vector (equation (8)) is calculated by the heat balance equation expressed by the above equation (2) every three control cycles, and an evaluation function is configured with the influence coefficient vector as a coefficient of equation (10). did. Under the constraint conditions (12) to (15) and (18), the evaluation function should be optimized by linear programming, and each combustion zone (first heating zone, second heating zone, soaking zone) should be set The furnace temperature was calculated. The predicted fuel consumption at this time was also calculated. In calculating the influence coefficient vector, t ₁ was set to 30 minutes in the calculations of equations (5) and (6). Further, in the calculations of Equations (6) and (7), δT ^zi _f was 10 ° C., and in the calculation of Equation (16), δT ^z _f was 10 ° C. In order to optimize the evaluation function, the interior point method was adopted. The slab conditions to be heated were 164 slabs, slab thickness 250 mm to 300 mm, slab width 1100 mm to 2400 mm, slab length 900 mm to 5000 mm, and extraction target temperature 1060 to 1150 ° C.

  The simulation result of the transition of the furnace temperature in the example of the present invention is shown in FIG. Moreover, the transition of the predicted fuel consumption is shown in FIG.

(Comparative example)
This is a conventional method that employs a fixed value (1000, 100, 1) as a subsequent stage load as a coefficient of the evaluation function (Expression (10)). That is, the evaluation function J is

The transition of the furnace temperature and the predicted fuel consumption was calculated in the same manner as in the above-described example except that. In equation (20), ΔT ¹ _f is the amount of change in furnace temperature in the first heating zone, ΔT ² _f is the amount of change in furnace temperature in the second heating zone, and ΔT ³ _f is the amount of change in furnace temperature in the soaking zone. Represents.

  The simulation result of the transition of the furnace temperature in this comparative example is shown in FIG. Moreover, the transition of the predicted fuel consumption is shown in FIG.

(Evaluation results)
Comparing the changes in the fuel consumption of the above-described invention example and the comparative example (FIGS. 8 and 10), the fuel consumption of the comparative example is shown from time 12 to time 15 while it is almost the same until time 12. Compared to the fuel consumption of the example of the invention, the amount is drastically reduced particularly in the first heating zone and is increasing sharply in the second heating zone. After time 16, the fuel consumption of the first heating zone and the second heating zone of the comparative example is generally larger than the fuel consumption of the invention example under the influence of time 12 to time 15. .

As a result, the fuel consumption from time 6 to time 24 was Comparative Example 43062Nm ³ and Invention Example 36132Nm ³ , and the fuel consumption in the Invention Example could be reduced by about 16.1% compared to the Comparative Example.

  From the above experimental results, it was shown that according to the furnace temperature setting method of the continuous heating furnace of the present invention, the furnace temperature setting in the continuous heating furnace can be performed while effectively reducing the fuel consumption. .

  While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. Rather, it can be changed as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification, and a furnace temperature setting method and furnace temperature control system for a continuous heating furnace with such changes, Continuous heating furnaces, as well as methods for producing metallic materials, should also be understood as being within the scope of the present invention.

  The furnace temperature setting method and furnace temperature control system of the continuous heating furnace of the present invention can be suitably used for the furnace temperature setting of the continuous heating furnace, and the continuous heating furnace of the present invention is suitable for heating metal materials. Moreover, the manufacturing method of the metal material of this invention can be used suitably for manufacture of the metal material which requires a heating.

DESCRIPTION OF SYMBOLS 1 Furnace wall 2 Pre-tropical zone 3 1st heating zone 4 2nd heating zone 5 Soaking zone 6 Skid 7 Slab inlet 8 Slab extraction port 9 Slab 10 Continuous heating furnace 11 Control means 12 Storage means 13 Input means 14 Output means 15 Furnace Temperature measuring means 15a, 15b, 15c, 15d Furnace temperature sensor 16 Pre-charging slab temperature measuring means 17 Furnace temperature adjusting means 20 Furnace temperature control system for continuous heating furnace 21a, 21b, 21c, 21d Burner 30 Continuous heating furnace

Claims (6)

A furnace temperature setting method for a continuous heating furnace in which a set temperature of at least one combustion zone is updated every predetermined control cycle,
Using the heat balance equation showing the heat input and output in each combustion zone that updates the set temperature, the influence coefficient that evaluates the effect of the furnace temperature change in each combustion zone on the fuel consumption of the entire continuous heating furnace is calculated. An influence coefficient calculation step,
An evaluation function configuration step that configures an evaluation function with the influence coefficient as a coefficient and the furnace temperature change amount of each combustion zone as a variable;
A constraint condition determining step for determining a constraint condition imposed on the furnace temperature change amount of each combustion zone;
A set furnace temperature change amount determination step that calculates a furnace temperature change amount of each combustion zone that optimizes the evaluation function under the constraint conditions and sets a set furnace temperature change amount;
A set temperature update step of updating the set temperature of each combustion zone according to the set furnace temperature change amount;
A furnace temperature setting method for a continuous heating furnace, comprising:   The furnace temperature setting method for a continuous heating furnace according to claim 1, wherein the evaluation function is a function representing a predicted amount of fuel consumption accompanying a change in furnace temperature of the combustion zone. The evaluation function configured in the evaluation function configuration step is linear,
The constraints determined in the constraint determination step are all linear;
The furnace temperature setting of the continuous heating furnace according to claim 1 or 2, wherein, in the set furnace temperature change amount determination step, calculation of a furnace temperature change amount of the combustion zone that optimizes the evaluation function is performed by a linear programming method. Method.   The furnace temperature control system of a continuous heating furnace characterized by setting the furnace temperature of a combustion zone by the furnace temperature setting method of the continuous heating furnace of any one of Claims 1-3.   A continuous heating furnace comprising the furnace temperature control system for a continuous heating furnace according to claim 4.   A method for producing a metal material, comprising the step of heating the metal material using the continuous heating furnace according to claim 5.