JP6237492B2 - Heating furnace heating control device, combustion control method, rolled material manufacturing method - Google Patents

Description

  The present invention relates to a technique for controlling the heating temperature of a continuous heating furnace that continuously heats a steel material to be heated and a method for manufacturing a rolled material using the technique.

  In the conventional continuous heating furnace combustion control method, the extraction pitch of steel from the heating furnace is predicted, the furnace temperature required to bake to the target temperature at the time of extraction is calculated, and the calculated furnace temperature is set. The fuel flow rate is controlled (Patent Document 1). In other words, with regard to the steel material temperature, focusing on the target extraction temperature at the time of extraction, the furnace temperature setting in each heating zone required to bake the target steel material from the steel material temperature at the time of charging (current) to the target extraction temperature The value is calculated based on a furnace temperature setting model such as a one-dimensional or two-dimensional heat transfer model. And heating control of a heating furnace is performed so that the temperature of steel materials reaches predetermined temperature by the time of extraction.

JP 7-258752 A

In the control method described in Patent Document 1, it is necessary to predict the extraction pitch of the steel material, predict the in-furnace time in the entire heating furnace of each steel material from the predicted extraction pitch, and heat the steel material based on the furnace temperature setting model A proper furnace temperature is set, and combustion control is performed so that the set furnace temperature is obtained.
However, the in-furnace time during which the steel material stays in the heating furnace is usually a long time exceeding 3 hours. For this reason, the estimated time when the steel material charged in the heating furnace is predicted to be extracted tends to have a large error. And the larger the error, the more inappropriate the furnace temperature set when charging the steel material, and the greater the variation in the steel material temperature during actual heating furnace extraction with respect to the target extraction temperature.
The present invention has been made paying attention to the above points, and it is possible to set a more appropriate furnace temperature on the charging side, thereby reducing the variation in the steel material temperature at the time of extraction from the heating furnace. And

  In order to solve the above problems, a heating control apparatus for a heating furnace according to one aspect of the present invention is a heating control apparatus for a heating furnace that continuously heats a steel material to be heated while conveying the steel material to be heated. It is divided into two or more zones from the entry side to the extraction side, and the combustion control is performed individually in the divided zones, and the steel material temperature at the target zone entry side at least for the charge side zone , The estimated temperature calculation unit for estimating the temperature of the steel material required on the next zone entry side of the target zone, and the stay time for estimating the stay time of the target zone of the steel material to be heated The furnace temperature in the target zone is set from the estimation part, the steel material temperature acquired by the entry side temperature acquisition part, the steel material temperature estimated by the estimation temperature calculation part, and the stay time estimated by the stay time estimation part. A furnace temperature setting unit, And wherein the door.

  Moreover, the combustion control method for a heating furnace according to one aspect of the present invention is a combustion control method for a heating furnace that continuously heats a steel material to be heated while conveying the steel material to be heated from the charging side to the extraction side. It is divided into two or more zones, and combustion control is individually performed in the divided zones. At least the charging side zone, the steel material temperature at the target zone entry side, the target zone temperature Set the furnace temperature in the target zone based on the required steel temperature at the next zone entry side and the residence time of the target steel zone to be heated, and set the furnace temperature in the target zone Thus, the fuel flow rate and the air flow rate are controlled.

  At this time, all zones are targeted, and for each zone, the steel material temperature at the target zone entry side, the steel material temperature required at the next zone entry side of the target zone, the zone targeted for the steel material to be heated Set the furnace temperature in the target zone based on the staying time, and control the fuel flow rate and the air flow rate so that the furnace temperature in the target zone becomes the set furnace temperature. The target extraction temperature in the heating furnace may be set as the steel material temperature required on the zone entry side next to the zone.

  The rolled material manufacturing method according to an aspect of the present invention is a rolled material manufacturing method in which a rolled material is manufactured by hot rolling a steel material extracted from a heating furnace that is continuously heated while conveying the heated steel material. Then, controlling the combustion of the heating furnace by the combustion control method of the heating furnace according to the above aspect, calculating the target extraction temperature in the heating furnace from the target temperature of the rolled material after the hot rolling, and calculating the calculated target Based on the extraction temperature, the steel material temperature required on the zone entry side next to the target zone is estimated.

According to the present invention, it is possible to make the heating amount of the steel material on the charging side in the heating furnace appropriate, so that it is possible to reduce the variation in the steel material temperature at the time of extraction of the heating furnace. As a result, there are effects of improving the fuel consumption rate of the heating furnace by preventing overheating and shortening the extraction stop time due to insufficient heating of the steel material to be heated.
Moreover, according to this invention, it becomes connected with the improvement of the quality accuracy of the rolling material after the hot rolling by the next process because the dispersion | variation in the steel material temperature at the time of heating furnace extraction becomes small.
The present invention is particularly effective for a steel material having a narrow target extraction temperature range, for example, a technique suitable for a steel material that needs to be controlled to have a narrow target extraction temperature range.

It is a conceptual diagram explaining the rolling material manufacturing equipment which concerns on embodiment based on this invention. It is a figure which shows the structure of the combustion control part which concerns on embodiment based on this invention.

Next, embodiments of the present invention will be described with reference to the drawings.
(Constitution)
As shown in FIG. 1, the rolled material manufacturing facility of the present embodiment includes a continuous heating furnace 1 and a hot rolling facility 2.
The heating furnace 1 is usually divided into three or four zones. In this embodiment, as shown in FIG. 1, the case where it divides into three zones, the pretropical 1A, the heating zone 1B, and the soaking zone 1C is illustrated. In the present embodiment, as an example of zoning for setting the furnace temperature, in the present embodiment, the zone is divided into two zones, a pretropical zone 1A, and a heating zone 1B and a soaking zone 1C.

And the steel material 3 (slab) produced by casting with a continuous casting machine (not shown) is continuously charged into the heating furnace 1, and the steel material 3 has a pretropical 1A, a heating zone 1B, and a soaking zone 1C. While passing, it is heated for about 3 to 4 hours. Further, the heated steel material is sequentially extracted from the heating furnace 1 and subjected to rolling by a hot rolling facility (not shown) to become a target rolled material.
In the heating furnace 1, combustion control is performed for each zone so that the set furnace temperature is set. That is, the combustion controller 6 constituting the heating controller acquires the measured values of the ambient thermometers 4a, 4b, and 4c including thermocouples installed on the furnace wall, and each band obtained from the measured furnace temperature measured values. The fuel flow rate and the air flow rate provided in each zone are adjusted so that the ambient temperature becomes the set furnace temperature set value. In FIG. 1, the code | symbol 5 has shown the burner which heats each belt | band | zone.

As shown in FIG. 2, the combustion controller 6 includes a charging temperature calculation unit 6A, a target extraction temperature calculation unit 6B, a steel material temperature calculation unit 6C, an extraction pitch prediction unit 6D, a heating zone entry side steel material temperature acquisition unit 6E, A tropical in-furnace time calculation unit 6F, a next stage in-furnace time calculation unit 6G, a heating zone entry side target temperature estimation unit 6H, a pre-tropical temperature setting unit 6I, a next stage zone temperature setting unit 6J, and a fuel flow rate setting unit 6K are provided. .
The charging temperature calculation unit 6A calculates the charging temperature of the steel material 3 from the time required to move from the continuous casting machine to the heating furnace 1 based on the steel material temperature measured on the exit side of the continuous casting machine (not shown). . The charging temperature calculation unit 6A may be obtained by directly measuring the temperature of the steel material 3 on the heating furnace 1 entry side.

  The target extraction temperature calculation unit 6B calculates a target temperature at the time of heating furnace extraction. The target extraction temperature calculation unit 6B calculates the target temperature at the time of extraction in the heating furnace using, for example, the material temperature drop model in the rolling line from the delivery-side target temperature and product dimensions of the hot rolling mill. That is, the target extraction temperature calculation unit 6B determines a steel target temperature (target extraction temperature) at the time of extraction in consideration of a temperature drop in the rolling mill. In addition, when the heating temperature is regulated for the purpose of controlling the dissolution / precipitation behavior of precipitates in steel in the steel heating stage before hot rolling, the target temperature at the time of extraction in the furnace is set according to the conditions. Can be calculated.

The extraction pitch prediction unit 6D predicts the steel material extraction pitch from the heating furnace 1 from the rolling schedule and the target rolling amount. From this predicted extraction pitch, the conveyance speed at which the steel material 3 passes through the furnace is predicted.
The steel material temperature calculation unit 6C calculates the temperature of the steel material 3 in the furnace at a predetermined sampling period based on the furnace temperature results of the bands 1A, 1B, and 1C in the heating furnace 1.
The heating zone entry side steel material temperature acquisition unit 6E acquires the temperature of the steel material 3 entering the heating zone 1B. The heating zone entry side steel material temperature acquisition part 6E calculates the temperature of the steel material 3 which transfers from the pretropical 1A to the heating zone 1B based on the measured value of the atmospheric thermometer 4a installed in the exit side vicinity of the pretropical 1A, for example. Alternatively, the temperature of the steel material 3 entering the heating zone 1B is acquired from the calculated value of the steel material temperature calculation unit 6C.

  The pre-tropical in-reactor time calculation unit 6F calculates the remaining in-reactor time existing in the pre-tropical 1A of the preceding steel material 3 charged in the pre-tropical 1A from the extracted pitch obtained by the extracted pitch prediction unit 6D. Then, from the calculated in-furnace time, the in-furnace time of the pre-tropical zone 1A of the steel material 3 to be charged into the heating furnace 1 is determined. Specifically, the total value of the rolling times of the preceding all steel materials 3 existing in the pre-tropical zone 1A is set as the predicted in-furnace time of the pre-tropical zone 1A of the steel material 3 to be charged into the heating furnace 1 from now on.

  The next stage in-furnace time calculation unit 6G remains from the extraction pitch obtained by the extraction pitch prediction unit 6D until it is extracted from the heating furnace 1 of the preceding steel material 3 charged in the heating zone 1B and the soaking zone 1C. Each in-furnace time is calculated, and from the calculated in-furnace time, the in-furnace time until the steel material 3 charged in the heating zone 1B is extracted is obtained. Specifically, the total value of the rolling times of the preceding all steel materials 3 existing in the heating zone 1B and the soaking zone 1C is set as the in-furnace time until the furnace extraction of the steel materials 3 charged in the heating zone 1B. .

  The heating zone entry side target temperature estimation unit 6H calculates the target temperature on the entry side of the heating zone 1B of the steel material 3 charged in the heating furnace 1. The heating zone entry side target temperature estimation unit 6H acquires the steel material target temperature (target extraction temperature) at the time of extraction from the target extraction temperature calculation unit 6B, and each steel material in the furnace from the extraction pitch obtained by the extraction pitch prediction unit 6D. The remaining in-furnace time in the heating zone 1B and the soaking zone 1C is calculated, and the in-furnace in the heating zone 1B and soaking zone 1C of the steel 3 to be charged into the heating furnace 1 is calculated from the calculated in-shutdown time. Predict time (time to extraction). And the heating zone entrance side target temperature estimation part 6H sets the steel material target temperature at the time of extraction, the predicted heating time in the heating zone 1B and the soaking zone 1C, the furnace temperature setting value of the present heating zone 1B and soaking zone 1C. It is used as a parameter, and based on a one-dimensional or two-dimensional heat transfer equation (heat transfer model), a target temperature on the heating zone 1B inlet side where the steel material temperature during extraction becomes the target extraction temperature is estimated.

  The pre-tropical temperature setting unit 6I calculates the furnace temperature setting value of the pre-tropical 1A. The pre-tropical temperature setting unit 6I assumes that the steel material 3 to be charged into the heating furnace 1 is present in the pre-tropical zone 1A only for the in-furnace time obtained by the pre-tropical in-reactor time calculation unit 6F. The temperature of the pre-tropical zone 1A required for setting the target temperature on the heating zone 1B inlet side determined by the heating zone inlet side target temperature estimation unit 6H from the steel material temperature calculated by the inlet temperature calculator 6A is one-dimensional or 2 Calculated based on the dimensional heat transfer equation (heat transfer model).

  The next zone temperature setting unit 6J obtains the furnace temperature set values for the heating zone 1B and the soaking zone 1C. The next zone temperature setting unit 6J assumes that the steel material 3 transitioning to the heating zone 1B exists in the heating zone 1B and the soaking zone 1C for the duration of the in-furnace time obtained by the next zone in-furnace time calculating unit 6G. The steel material 3 to be transferred is a one-dimensional or two-dimensional heat transfer equation (heat transfer model) for each temperature in the heating zone 1B and the soaking zone 1C necessary to obtain the target extraction temperature at the time of extraction from the current steel material temperature. ).

The fuel flow rate setting unit 6K includes the furnace temperature setting values of the zones 1A, 1B, and 1C obtained by the pre-tropical temperature setting unit 6I and the next zone temperature setting unit 6J, and the ambient temperatures of the zones 1A, 1B, and 1C. From the furnace efficiency, the fuel flow rate and the air flow rate for setting the temperatures of the bands 1A, 1B, and 1C to the furnace temperature set values are calculated. In practice, the fuel flow rate is often set to an operation amount for cascade control of the furnace temperature.
The furnace efficiency is the amount of heat increase (° C.) of the steel material 3 when the gas 1Nm ³ is charged, and is obtained in advance by experiments or the like for each of the bands 1A, 1B, 1C. Although there are many factors affecting the furnace efficiency, for example, a graph of the amount of gas input on the horizontal axis and a graph of the heating amount of the steel strip on the vertical axis is obtained in advance for each of the bands 1A, 1B, 1C as a linear linear approximation formula, for example. The slope of the first order approximate expression is used as an index of the furnace efficiency.

The combustion operation units 7a, 7b, and 7c of the bands 1A, 1B, and 1C are operated so that the fuel flow rate and the air flow rate calculated by the fuel flow rate setting unit 6K are obtained.
Here, the charging temperature calculation unit 6A and the heating zone entry side steel material temperature acquisition unit 6E constitute an entry side temperature acquisition unit. The heating zone entry side steel material temperature acquisition unit 6E constitutes an estimated temperature calculation unit. The pre-tropical in-reactor time calculation unit 6F and the next-stage in-reactor time calculation unit 6G constitute a stay time estimation unit. The pre-tropical temperature setting unit 6I and the next stage zone temperature setting unit 6J constitute a furnace temperature setting unit.

(Heating and rolling treatment of steel 3)
The steel material 3 is continuously charged into the heating furnace 1 and heated to the target extraction temperature while passing through the pre-tropical zone 1A, the heating zone 1B, and the soaking zone 1C in the heating furnace 1. Furthermore, the steel 3 which are successively extracted from the heating furnace 1, the hot rolling set Bei Therefore being rolled, the rolled material of interest.
In the present embodiment, combustion control when the steel material 3 is heated in the heating furnace 1 is performed as follows.

  That is, for the steel material 3 charged into the heating furnace 1 (charged into the pre-tropical zone 1A), the target temperature at the inlet side of the heating zone 1B is calculated by calculating backward from the target extraction temperature when extracting from the heating furnace 1. Moreover, about the steel material 3 charged into the heating furnace 1, the in-furnace time in the pretropical 1A is estimated. And the present steel material temperature at the time of heating furnace charging, the target temperature in the heating zone 1B entrance side, the estimated in-furnace time in the pretropical 1A are used as parameters, and the heating furnace 1 is set based on a known heat transfer model. The furnace temperature set value for the pre-tropical zone 1A necessary for setting the temperature of the steel material 3 to be charged at the outlet side of the pre-tropical zone 1A as the target temperature at the inlet side of the heating zone 1B is obtained and set to the furnace temperature set value. Then, the fuel flow rate required in the pre-tropical zone 1A is determined, and the combustion control (heating control) in the pre-tropical zone 1A is performed so as to achieve the determined fuel flow rate.

  In addition, when the deviation between the furnace temperature set value for each steel material 3 previously charged in the pre-tropical zone 1A and the furnace temperature set value of the steel material 3 to be charged in the pre-tropical zone 1A is a predetermined value or more, for example, The largest furnace temperature setting value is adopted so that there is no insufficient heating of the steel material to be heated. It is good also considering the average value of the furnace temperature setting value of all the steel materials 3 which exist in the pretropical 1A as the furnace temperature setting value of the present pretropical 1A. Usually, since the target extraction temperature of the steel material 3 continuously charged in the heating furnace 1 is the same value or an approximate value, the latest furnace temperature setting value (the furnace temperature setting value of the steel material 3 to be charged from now on) is set. Alternatively, it may be set as the furnace temperature setting value of the current pre-tropical zone 1A. The same applies to the heating zone 1B and soaking zone 1C described later.

  Moreover, the in-furnace time in the heating zone 1B and the soaking zone 1C is predicted about the steel material 3 which is heated in the pre-tropical zone 1A and subsequently moves to the heating zone 1B. And the present steel material temperature at the time of the transition to the heating zone 1B, the target temperature at the time of extraction from the heating furnace (the target extraction temperature may be calculated again at the time of the transition to the heating zone 1B), the heating zone 1B and the soaking zone 1C The heating zone 1B and the soaking zone required to make the current temperature of the steel material 3 moving to the heating zone 1B the target temperature at the time of extraction based on a known heat transfer model, with the predicted in-furnace time as a parameter Each furnace temperature set value of 1C is obtained, and necessary fuel flow rates are determined in the heating zone 1B and the soaking zone 1C so as to be the furnace temperature set value, and the heating zone is set so as to obtain the determined fuel flow rate. Combustion control (heating control) is performed in 1B and soaking zone 1C.

  Here, for the steel material 3 charged into the heating furnace 1 as in the prior art, when the furnace temperature set temperature in each zone 1A, 1B, 1C is set directly from the target extraction temperature at the time of extraction based on the heat transfer model, From the accumulation of errors in the in-furnace time of the entire heating furnace of the preceding steel material 3 that has been heated in advance, the prediction accuracy of the in-furnace time in the pre-tropical zone 1A farthest from the extraction position is poor. The accuracy of the furnace temperature setting value at 1A was poor. For example, if 30 steel materials 3 can be charged in the heating furnace 1, the in-furnace time of the steel materials 3 to be charged from now is obtained from the sum of the predicted rolling times of all 30 preceding steel materials 3. Because.

On the other hand, in the present embodiment, the in-furnace time in the pretropical zone 1A of the steel material 3 to be charged from only the preceding steel material 3 (for example, 12 steel materials 3) existing in the pretropical zone 1A in the heating furnace 1 is used. Therefore, the accuracy of heating control in the pre-tropical 1A is improved.
Furthermore, the heating zone 1B and the soaking zone 1C only from the preceding steel material 3 (for example, 18 steel materials 3) existing in the heating zone 1B and the soaking zone 1C in the heating furnace 1 again on the entrance side of the heating zone 1B. Therefore, the accuracy of heating control in the heating zone 1B and the soaking zone 1C is also improved.

As a result, in the present embodiment, it is possible to reduce the variation in the steel material temperature at the time of extraction in the heating furnace. As a result, it is effective in improving the fuel consumption rate of the heating furnace 1 by preventing overheating and shortening the extraction stop time due to insufficient heating of the steel material to be heated.
Moreover, since the dispersion | variation in the steel material temperature at the time of a heating furnace extraction becomes small, it leads to the improvement of the quality precision of the rolling material after the hot rolling in the next process.
The method of the present embodiment is a technique that is particularly suitable for the manufacture of steel materials that require a narrow control of the extraction temperature range.
Although it may be possible to improve the accuracy by repeatedly calculating at a predetermined sampling period so that the target extraction temperature is obtained using the heat transfer model, there is a problem that the calculation load increases.

Here, the above embodiment exemplifies a case where the furnace temperature set values for the zones 1A, 1B, and 1C are calculated assuming two zones of the pre-tropical zone 1A, the heating zone 1B, and the soaking zone 1C. ing. The present invention is not limited to this. For example, the heating zone 1B is further divided into two zones (first heating zone and second heating zone), the target temperature on the second heating zone entry side is obtained, and from the target temperature on the second heating zone entry side, You may make it calculate the furnace temperature installation value of a 1st heating zone based on this invention. That is, the present invention may be applied by dividing the inside of the heating furnace 1 into three zones for determining the furnace temperature set value.
Moreover, in this embodiment, the furnace temperature setting value in the heating zone 1B and the soaking zone 1C is calculated from the actual steel material temperature on the heating zone 1B entrance side. Instead of this, the furnace temperature set values in the heating zone 1B and the soaking zone 1C may be obtained from the steel material temperature and the target extraction temperature at the time of charging in the heating furnace as in the past.

DESCRIPTION OF SYMBOLS 1 Heating furnace 1A Pre-tropical 1B Heating zone 1C Soaking zone 3 Steel materials 4a, 4b, 4c Atmosphere thermometer 5 Burner 6 Combustion controller 6A Charge temperature calculation part 6B Target extraction temperature calculation part 6C Steel material temperature calculation part 6D Extraction pitch prediction part 6E Heating zone entry side steel temperature acquisition unit 6F Pre-tropical in-reactor time calculation unit 6G Next stage in-reactor time calculation unit 6H Heating zone entry side target temperature estimation unit 6I Pre-tropical temperature setting unit 6J Next stage zone temperature setting unit 6K Fuel flow rate Setting section

Claims (4)

A heating control device for a heating furnace that continuously heats a steel material to be heated,
The heating furnace is divided into two or more zones from the charging side toward the extraction side, and combustion control is individually performed in the divided zones.
For at least the charging zone,
An entry-side temperature acquisition unit for acquiring the steel material temperature at the target zone entry side;
An estimated temperature calculation unit that calculates a target extraction temperature when moving to a target zone and estimates a steel material temperature required on the next zone entry side of the target zone based on the target extraction temperature ;
A residence time estimation unit for estimating the residence time of the zone to be heated by the steel material;
The furnace temperature setting unit for setting the furnace temperature in the target zone from the steel material temperature acquired by the entry side temperature acquisition unit, the steel material temperature estimated by the estimated temperature calculation unit, and the stay time estimated by the stay time estimation unit When,
A heating control device for a heating furnace, comprising: It is a combustion control method of a heating furnace that continuously heats steel material to be heated,
The heating furnace is divided into two or more zones from the charging side toward the extraction side, and combustion control is individually performed in the divided zones.
Next to the target zone calculated based on the target extraction temperature by calculating the target extraction temperature when moving to the target zone, at least for the charging side zone The furnace temperature in the target zone is set based on the steel material temperature required on the zone entry side and the staying time of the target zone of the steel to be heated, and the furnace temperature in the target zone is set above. A combustion control method for a heating furnace, wherein the fuel flow rate and the air flow rate are controlled so that For all zones, for each zone, the steel material temperature at the target zone entry side, the steel material temperature required at the zone entry side next to the target zone, the residence time of the target steel material to be heated Based on the above, the furnace temperature in the target zone is set, and the fuel flow rate and the air flow rate are controlled so that the furnace temperature in the target zone is set,
In the last zone, the target extraction temperature in the said heating furnace is again calculated | required and set as a steel material temperature required in the zone entrance side next to the zone of interest, The heating furnace of Claim 2 characterized by the above-mentioned. Combustion control method. A rolled material manufacturing method for manufacturing a rolled material by hot rolling a steel material extracted from a heating furnace that continuously heats the steel material to be heated,
The combustion control method according to claim 2 or 3 is used to control combustion of the heating furnace,
The target extraction temperature in the heating furnace is calculated from the target temperature of the rolled material after the hot rolling, and the necessary steel material temperature is estimated on the next zone entry side of the target zone based on the calculated target extraction temperature. A rolled material manufacturing method characterized by comprising:

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