JPS584412A - Controlling method of continuous heating furnace - Google Patents

Abstract

PURPOSE:To know accurately the level required for a burning zone, by always noticing the steel stock groups at a place near the entrance of the burning zone and at a position where the effect of a heating furnace is largest. CONSTITUTION:The steel stock load value is obtained from the shifting speed of the steel stock within the furnace which is obtained from the past achievement of extraction and the estimated extraction of the future. The heat career value is obtained as the representative value of the mean temperature of the steel stock at the entrance 2 of a burning zone. The target value of the output side is obtained as the representative value of the mean temperature of the steel stock at the exit 3 of the burning zone. Based on these values, a required furnace temperature is calculated as the function value for a major unit steel stock group 10. For a minor unit steel stock group 10, a required furnace temperature is calculated as the representative value of the required furnace temperature when each steel stock stays. The weighted average value is set and controlled as a furnace temperature of the burning zone for the required furnace temperatures of both the major and minor unit steel stock groups 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling a continuous heating furnace, and particularly to a method for controlling a continuous heating furnace that can control the heating of a steel material to be heated to a temperature most suitable for hot rolling.

In general, the most important points in controlling the furnace temperature of each combustion zone in the operation of a multi-zone continuous heating furnace are the dimensions of the steel in the furnace,
The weight and moving speed (extraction pitch) are not constant, and the
It is unsteady in that the charged silver degree and target heating temperature are not always the same. Therefore, in order to perform operations that satisfy optimal heating conditions in terms of energy conservation and steel quality, it is necessary to quantify this unsteadiness and constantly recognize or predict its fluctuations. It is preferable to use a method that controls the furnace temperature or fuel input amount for each combustion zone.

In contrast, the conventional and general method is to define a heat transfer calculation model formula based on heat transfer calculations of steel materials in the furnace, calculate the current temperature of each steel material in the furnace, and calculate the current temperature of each steel material in the furnace. The target extraction temperature and minimum heat unit O heat pattern for each steel material are determined from the furnace time of each residue, and the furnace temperature or fuel input amount for each combustion zone is determined accordingly. be.

However, due to the above-mentioned unsteadiness, such a method does not accurately capture fluctuations in the combustion zone 0 heating load, that is, fluctuations in the amount of heat supplied to heat the steel material as desired; It has been pointed out that the heat transfer coefficient accuracy and reliability of the equation are not sufficient, so it cannot be said that this is a control method suitable for unsteady conditions. Moreover, considering that the dimensions, charging temperature, target extraction temperature, furnace time, etc. of steel materials differ for each steel material, it is normal to
In a continuous heating furnace Kj+-, which has only ~4 combustion zones, each steel sheet is processed according to the planned schedule.
It is impossible to extract at the target temperature deep inside.

To achieve this, the extraction schedule for steel material can be reduced to a sufficiently low pitch that it can follow the controllability of the furnace, or the furnace can be modified to subdivide the combustion zone along the length of the furnace, resulting in a fine-grained extraction schedule. Possible options include conducting narrower operations.

However, in the former case, high productivity, which is the greatest characteristic of a continuous heating furnace, is lost, and synchronization with the rolling function cannot be achieved, making it unsuitable. In addition, even in the latter case, it is difficult to implement because the equipment becomes large-scale and the reactor operation becomes complicated and difficult.

In this way, many proposals have been made for control methods for continuous heating furnaces, but the technology has not yet been completely established, and it is difficult to achieve a certain degree of variation in the extraction results of steel materials. As a result, improvements in quality, yield, and energy savings could not be expected. Therefore, conventionally, the problem has been how to reduce variations in steel material extraction temperature while maintaining energy savings and high productivity. This point is deeply related to which steel material to focus on among the steel materials located in each combustion zone, but the control methods for continuous heating furnaces that have been proposed in recent years have not been sufficiently evaluated and studied. If you don't have it, you'll be disappointed.

The present invention focuses on the above-mentioned problems, and from the viewpoint of the unsteady nature of continuous heating furnaces, it clarifies the target steel material(s) in the combustion zone to be controlled, quantifies the unsteady nature, and The purpose of the present invention is to provide a continuous heating furnace control method that controls the furnace temperature in the combustion zone and allows operation to satisfy optimal heating conditions. do.

In order to achieve the above object, the method for controlling a continuous heating furnace according to the present invention is aimed at controlling a large unit group of steel materials located near the inlet of each combustion zone, and a group of steel materials located ahead of the steel materials in the direction of progress of each combustion zone. Focusing on the small group of steel materials in the position of the highest thermal influence in the combustion zone, the steel material movement speed in the furnace is determined from the past extraction results and future extraction plans for the large group of steel materials. Thermal history value obtained as the representative value of the steel material average temperature at the time of entering the combustion zone, and the exit side interpolation value obtained as the representative value of the steel material target temperature at the exit of the combustion zone. , calculate the required furnace temperature obtained as a function value of these, and calculate the elapsed suitable time and actual furnace temperature for the small unit copper material group, and the preliminary lit residual residence time up to the exit of the combustion zone. , from the target heating Ii degree at the exit, calculate the required furnace temperature as a representative value of the required furnace temperature during remaining residence for each steel material, and calculate the F+]1g! of these large unit and small unit steel material groups. The weighted average value of the furnace temperature is set and controlled as the furnace temperature of the combustion zone. Accurately grasp the required heating level for the ej scissors combustion zone and jointly control the furnace temperature required by both steel groups, thereby reducing the variation in target, achieving high quality, and energy saving. I did it like that.

Embodiments of the present invention will be described in detail below using a six-zone continuous heating furnace as an example.

As shown in FIG. 1, the six-zone heating furnace l has upper and lower preheating zones 4.5
It is equipped with 6.7 upper and lower heating zones and 8.9 upper and lower soaking zones. The Ryowari 10a, which is the object to be heated, is charged sequentially from the charging port 2, moves toward the extraction port 3 while being heated, and is heated at the extraction port 3 to a degree a that is optimal for later hot compaction. It is something that is taken out. During combustion, it is necessary to control the heating conditions for the steel material 10 in each combustion zone 4 to 9 in order to match the final outlet target value at the extraction port 3.

Now, considering the upper heating zone 6 as the combustion zone to be controlled,
The following is a second example of a method for controlling the furnace temperature in the ζ0 combustion zone.
-Explanation based on.

When controlling the furnace temperature of this upper heating zone (hereinafter referred to as combustion zone 5) 6, there are certain considerations that must be taken into account, such as the heating conditions for the steel materials 10 currently in the furnace and the steel materials that will be introduced in the future. These are the necessary heating conditions for lO. This is because unless the current required heating level and future required heating level in the combustion zone 6 are properly understood, it is not possible to control the heating conditions to the optimum.

Then, we reach Jin's combustion zone 6! ! - IIcM that controls the furnace temperature by capturing the required heating level! A, the flame position or furnace temperature detection end 1 formed by the burner 11 of the combustion zone 6
A relatively small group of steel materials 14 corresponding to the position 2, and a large group of steel materials 1 located near the entrance of the combustion zone 6.
We will focus on 3.

That is, as mentioned above, considering the unsteadiness of the continuous heating furnace 1 and the fact that there are only 3 to 4 combustion control zones in the furnace length direction, when trying to control the furnace temperature in a certain combustion zone, it is difficult to control the The steel material to be heated can be considered to be one of the steel materials located within the zone that is subjected to the most severe heating conditions, or it can be considered as a group of steel materials that have been collected to a certain number.

9. Control] The factor that changes the future heating conditions of the burning zone lies in the steel material located near the entrance of the burning zone. For this reason, in this example, as shown in FIG. 2, among the steel materials 10 located in the combustion zone 6, a relatively large group of steel materials 13 (this Considering the position of the furnace temperature detection end 12 or the welfare burner IIC), a relatively small unit steel group 14 (referred to as a steel group) located at a position where the furnace operation influence, that is, the degree of thermal influence is the largest, is determined.
This will be referred to as the B steel material group). This can be done in large units for steel A in order to reflect fluctuations in the required heating level on the furnace temperature in the combustion zone, while for steel K it is necessary to do it in small units for steel B in order to perform a final check on the degree of baking. It is from. In particular, in this example, the number of human steel materials was 3.
Although the steel group B is made into one sheet, the size of both steel groups,
The position in the furnace may be different for each combustion zone, and it is desirable to determine the optimum position after thorough experimental verification in an actual furnace.

The ninth group of steel materials selected in this way has different required conditions, and therefore requires different set furnace temperatures. Soζ
First, focusing on steel group A, setting conditions for this steel group are determined. Since the setting conditions are unsteady and vary depending on the size of the steel group introduced into the combustion zone 6, extraction pitch, target temperature, etc., as a means to quantify this, "steel material load value", This is a tree that separates the factors into ``voice history value'' and ``output target value.''

First, the copper material load value MA of the steel material group relates to the dimensions, weight, and moving speed of the steel material, and can be expressed by the following equation.

MA=υ,XΣWmu/ΣpL, ,,,,,,,,,
, , , , , , , , , , , , (1) L
L Here, M^ is the steel load value (tm/H,) of the human steel group, ν
t is the moving speed (II /
Hr), WittA steel material A f) unit weight (
t@, Pb is the convergence (-) of the steel materials in the A steel material group (if there is a clearance between the steel materials, this is included).

The unit weight W↓ and width PLK of this A11lj material group can be easily known from tracking information.

In ζro, the moving speed 9t is the average speed at the current time 1, which was calculated by considering a time interval of 4t around the current time and including the steel material extraction results up until a little earlier than the present time and the future steel material extraction predictions. Calculated from the moving distance of A steel group. That is, it is obtained from the following formula.

C = X/ Δ・之 (Ga'/Hr) ・
・・・・・・・・・・・・・・・・・・・・・ (2
) where ζ, X is the distance (m) that the KA steel group moves within Δχ
, Δl is a time interval centered on the current time l.

In equation (2) above, in order to calculate Actual results and predictions are necessary. Regarding prediction, rolling capability and heating furnace 10
Depending on the size of the capacity, if the former exceeds the latter, the steel will be extracted at a predetermined extraction pitch depending on the type of steel in the heating furnace. Time prediction becomes possible. On the other hand, if the latter exceeds the former, the required rolling time is determined by the type of steel material, dimensions, rolling size, pressure schedule, etc., and it is possible to predict the extraction time in the same way. .

Note that for a pause that is known in advance, the required time may be added and modified.

In addition, the time interval No. 1 is determined in consideration of the extraction pitch, and is determined experimentally as a value that accurately expresses the change in the steel load value MAO and allows for a thorough discussion of its absolute value. It has been found that it is generally best to set the pitch to about I times the average extraction pitch.

Such steel material negative value M^ has a real-time and dynamic meaning, including not only the current and past movement results but also future movement predictions.

Next, the thermal history value HIA of the steel material group is determined. When the steel group has reached the inlet position of the combustion zone 6,
The movement history of these steel materials group A from the time they were transferred to the heating furnace 1 to the present can be known from the tracking information of the steel materials in the furnace. In addition, as a result of Jin-no-ma, the furnace atmosphere i1
Since the temperature and the charging temperature of the steel material group A are known, the heat transfer coefficient determined theoretically or experimentally in advance is used to calculate the heat transfer of the steel material in the heating furnace using the known heat transfer calculation method for the steel material in the heating furnace. For each steel material in the group, the average temperature (0 zone) ↓ of the steel material ↓ at the entrance of the gentle combustion zone 6 is calculated. For each group of human steel materials,
This steel material average temperature (θI)A is determined and its representative value is taken as the thermal history 11 [[HIM]. This representative value may normally be an average value, or a minimum value may be adopted depending on the situation, such as when there is a possibility of insufficient heating.

Furthermore, the output side target value HO^ of the A steel material group is determined in a gray manner. As mentioned above, it is possible to predict the extraction time from the extraction pitch of steel materials in the furnace, and the residence time at the extraction port 31 from the exit position of the combustion zone 6 for each steel material group for each steel material group. can be predicted.

Therefore, using the predicted value of this residence time, the target extraction temperature determined for each steel material, and the predicted value of the furnace atmosphere temperature O when passing from the outlet of the roaring combustion zone 6 to the extraction port 3, Using the heat transfer coefficient determined theoretically or experimentally, and using the known heat transfer calculation method for steel materials in the heating furnace, the average for each steel material for steel material group A at the exit of the roaring shell combustion zone 6 is calculated. The target temperature value (#,) can be calculated.

The outlet target value HOA is determined from the good steel average target temperature (-・) A obtained for each steel material in the A steel group.
#e) Determine using the representative value of i.

Typical value of ren The average value is usually sufficient, but depending on the situation, the maximum value may be taken. The reason for setting it to the maximum value is to prevent insufficient heating from occurring in the combustion zone 6.

Steel load value M and thermal history value H obtained in this way
The three factors consisting of I^ and outlet target value HO^ quantitatively represent the heating load of the combustion zone 6, that is, the furnace temperature level required by the steel material group, and the fluctuations in the heating load are caused by these factors. It appears as fluctuations in three factors. Therefore, the required furnace temperature θ^ of steel material group A, which is the setting condition for the combustion temperature 6, is expressed as a function value of the above 3111 factors as shown in the following equation.

θA wealth (Mmu, HI^, HOA) ・・・・・・・・・
(3) Here, the functional form F depends on the heat transfer characteristics of the six-scissor combustion zone 6, and given that the operation of the furnace is unsteady, it cannot be determined theoretically. Since rounding is difficult, it is desirable to have a nine-function form that has been thoroughly verified experimentally based on this rounding. Normally, this functional form can be expressed as a linear combination.

In addition, to calculate the extraction pitch prediction of in-furnace steel material and the predicted value of residence time in each zone, which are necessary to obtain the above values, it is effective to calculate the predicted rolling time value of each steel material using a pass schedule model of the compaction machine, etc. You can easily and accurately determine the rounding value.

On the other hand, the setting conditions for the B steel material group placed in the furnace at the position most exposed to thermal influence within the combustion zone 6 are determined as follows. That is, for this B steel material group, using the above-mentioned well-known heat transfer calculation method, we can calculate that the average temperature f('t) in the combustion zone 60 population and the target average temperature f at the exit of the same combustion zone are:
(#.) Le and seeking jin and is possible. In addition, using these values, the predicted residence time in the combustion zone 6, and the good heat transfer coefficient obtained theoretically or empirically in advance for the combustion zone 6, the above-mentioned known heat transfer calculation is performed. According to the law, it is possible to calculate in advance the target furnace temperature ($r) A that should be given to the steel group B when passing through the combustion zone 60.

Therefore, since the steel group B that is currently being targeted is close to the exit of the combustion zone 6, the furnace temperature and elapsed time from the entrance of the combustion zone 60 to the current position are known as actual values. Once the actual furnace temperature and actual elapsed time of the furnace and the predicted O residual residence time from the current position to the exit of the combustion zone 60 are known, it is possible to calculate The required furnace temperature (θflI)b required for the residence time of the residue to be heated at the target temperature tt is determined. In this case, the predicted residence time depends on the rolling mill bus schedule as described above.
It can be easily determined from Therefore, the setting conditions for each steel group B are the actual furnace temperature up to the current position, the actual elapsed time, the preliminary III remaining haw time, and the target furnace temperature at the time of passing through the combustion zone (#: ) The required reactor calculated based on A is given as ll1(ne#rm)↓. However, the required furnace temperature* Temperature←Sl)A is @standard furnace temperature (θ
1) It is desirable to use ↓ as the lower limit.

The required furnace temperature ('y+a)io representative value of each B steel material group calculated in this way is taken as the required furnace temperature θl of the B steel material group, and the representative value may normally be an average value, but depending on the situation, the maximum value. In addition, in the embodiment, rounding is uniquely determined for one piece of steel material.

Next, when the required furnace temperature θ^ for the steel material group B and the required furnace temperature θ^ for the B steel material group are determined as described above in 1, the set furnace temperature θ of the combustion zone 6 to be controlled is determined. , is determined by the weighted average of both. That is, it is determined by formula 7, where g and h are weighting coefficients.

The weighting coefficients a and j in the above equation (4) are arbitrarily determined depending on the actual furnace situation and the furnace operation target. That is, for materials with very strict heating temperature requirements, θ, and em (DI & large value (&a ≧810 and @ g −1, h −0.

θ = 0 and g m Q , -1), and if a little early ripening is allowed for the regeneration heating temperature j[g)! It is sufficient to adopt weighting coefficients which are determined experimentally.

Specifically, in the thick plate heating furnace, in the heating zone, Hiro, lθmu θml≦1lQcO and 龜−1, Haruka=1, lθmu−θ
■, 1 > g o c and its own maximum value were selected and set, and in the soaking zone, θ um and θ, 0 maximum value were selected and set.

FIG. 3 shows a 70-chart for setting the furnace temperature of each combustion zone according to the present embodiment. As shown in this figure, for each combustion zone, the M steel group and the B steel group are searched, and the steel load value M, thermal history value HIA, and output side target value HO are determined for the human steel group. In addition to calculating the required furnace temperature θm, the passing target furnace temperature (#
t) ↓, entrance] Calculate the actual furnace temperature, actual time, and residence time of the remaining waste up to the current position, and calculate the required furnace temperature θ. Next, based on the obtained required furnace temperatures θ and θl, weighting coefficients are set appropriately.
The combustion zone is controlled to the combustion furnace temperature θ.

FIG. 4 shows the results of nine control examples carried out in accordance with such an embodiment. The upper part of this figure shows the results of the control performed by selecting the maximum values of θ and θ in response to severe target heating conditions. was measured. Note that the chain line is the target extraction temperature. The lower part of i9 shows the control results for the overpressure machine, which was carried out with the p1 weight intermittent set to 6 mg and Awl.

As described above, according to this embodiment, by always focusing on the steel groups near the entrance of the combustion zone to be controlled and at the position where the furnace operation shadow is most likely to change, it is possible to control the combustion zone. It is possible to accurately grasp the required level of demand. 9. Understand the fluctuations in the required heating level from the steel material group in advance, and
By checking the firing temperature from a group of copper materials, it becomes possible to perform advanced control by combining the required furnace temperatures of both of them. Furthermore, it is also possible to significantly reduce the variation in the actual value with respect to the target heating temperature of the steel material. especially,
It fully reflects the unsteadiness of continuous heating furnaces and allows nine-way control.The variation in temperature relative to the target temperature is halved, and the fuel consumption rate can be reduced by approximately 3 to 4 times, resulting in a large energy-saving effect. By improving plate thickness accuracy〉Yield〉
However, it is possible to obtain favorable results such as an improvement in O, OS%, quality and yield), and a large improvement effect.

1. This embodiment can be applied to other furnaces with different furnace layers, burner arrangements, and types of copper materials, and is therefore versatile. others,
It goes without saying that the present invention can also be applied to heat treatment furnaces and heat treatment furnaces having multiple combustion zones.

As explained above, according to the present invention, in terms of energy saving,
It is possible to accurately provide the optimum heating conditions in terms of quality, and there is an effect that the steel to be heated can be extracted at the second temperature with little variation.

[Brief explanation of the drawings] Part 1- is a cross-sectional view of the 6-temperature continuous heating furnace, Part 2- is a cross-section of the combustion zone to be controlled, Part 3 is a flowchart showing the control method -1, Part 4 is an example It is a figure which shows the extraction temperature of the steel material extracted by applying. 1. Continuous heating furnace, 10... Steel material, 11... Burner, 1jl-F temperature detection end, 13... A copper material group, 14...
・B steel group. Agent Tatsuyuki Unuma (and 2 others)

Claims (1)

[Claims] (1) For each combustion zone of a multi-zone continuous heating furnace, there is one group of large units of copper material located near the entrance of the combustion zone, and a group of large units of copper material located near the entrance of the combustion zone, and a large group of copper materials located in the forward direction of the steel material progressing direction and at the farthest point of the scissors combustion zone. Focusing on the small unit steel material group at a position with a high degree of thermal influence O, the steel material load value obtained from the steel material movement speed in the furnace obtained from the past extraction results and future extraction predictions for the large unit steel material group, and the steel material load value From the thermal history value obtained as a representative value of the steel material average temperature at the entrance of the combustion zone and the exit side target value obtained as the representative value of the steel material target temperature at the combustion zone exit, the demand furnace is determined as a function value of these values. The temperature is calculated, and the steel material is calculated based on the actual elapsed time and actual furnace temperature for the small unit steel material details, the predicted residual bud retention time up to the exit of the Shoson combustion zone, and the target heating temperature at the combustion exit. Calculate the required furnace temperature as a representative value of the required furnace temperature during retention of each residue, and set the weighted average value of both the required furnace temperatures of the large unit and small unit steel material groups as the furnace temperature of the combustion zone. A continuous heating furnace control method that takes this into account.