JPS5845324A - Furnace temperature setting method of continuous heating furnace - Google Patents

Abstract

PURPOSE:To heat a material to an optimum temperature by the minimum energy consumption, by calculating a future furnace temperature in a period of time when a material to be heated exists in an extracting port of the furnace in the future, and changing the future furnace temperature to a designated furnace temperature so that a target extracted temperature can be obtained at a scheduled time. CONSTITUTION:In a continuous heating furnace of a slab, etc., a future furnace temperature in a period of time when a material to be heated Si exists in an extracting port of the furnace in the future is calculated in accordance with a future furnace temperature against materials S1-Si-1 nearer to the extraction side than the material Si, a present temperature and a target extracted temperature and a target extracted temperature of the material Si, and a scheduled extracted time of the materials S1-Si. In case when this future furnace temperature has exceeded a designated temperature, the temperature of the material Si is calculated in accordance with a time so that the target extracted temperature can be obtained at the scheduled extracted time of the material Si. At the point of time when this temperature coincides with the temperature of the material Si heated in accordance with the future furnace temperature against the materials S1-Si-1, the future temperature decided for the materials S1-Si-1, the future temperature decided for the materials S1-Si-1 is changed to a designated furnace temperature. In this way, the material can be heated to a temperature which is suitable for the following process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a furnace temperature setting method for a continuous heating furnace for heating slabs and the like.

Continuous heating furnaces (hereinafter simply referred to as heating furnaces) must be operated in such a way as to heat the material to be heated to a temperature suitable for subsequent processes while keeping energy consumption to a minimum, and to ensure the target production volume.

The biggest problem in operating this heating furnace is how to set the furnace temperature when the load inside the furnace fluctuates, that is, when materials to be heated of different sizes are mixed in the same furnace. It's up to you.

To explain this using FIG. 1, inside the heating furnace 1 equipped with the burner 2, there are slabs 8□, 81, .

lit..., 8m are arranged, slabs S1 to 1ii
- If the dimensions, for example, thicknesses of slabs B1 to In are different from each other, the slab 8 is thinner. On the left, where the furnace temperature is set for ~81-1, the thick slabs s1 to 8n lack sintered sand, which causes a big problem in the subsequent process. On the other hand, thick slab 1
If the furnace temperature is set for 1i to In, the slabs 81 to s1-□, which are closer to the extraction port than the slab S1, will be overcooked, which will not only increase the p1 scale but also waste energy.

As is well known, it is impossible to set the temperature for each slab individually because it takes a considerable amount of time for the actual humidity of the heating furnace to reach the set value.

Therefore, a method can be considered in which the time interval for extracting slabs, that is, the extraction pitch, is changed and the slab is extracted when the slab reaches a predetermined degree, but this extraction pitch is unnecessarily changed in relation to the subsequent process. In many cases, this is not possible.

Therefore, conventionally, the slab S was
I hope that the slabs S1 to 51-8 on the extraction port side will not be overcooked, or that even if some of these slabs are overcooked, the number of them will be as small as possible. The operator had set the furnace temperature of the heating furnace so that at least the slag S1 reached the target extraction humidity.

In this way, when the operator sets the furnace temperature, he must be familiar with the 5 dimension information, current single information, target extraction temperature information, extraction pitch information, etc. for all slabs in the furnace. However, there were naturally limits to the operator's intuition, and it was impossible to precisely set the furnace temperature.

The present invention was made in consideration of the Queen's needs, and it heats the material to be heated to 11 f suitable for the subsequent process while minimizing energy consumption and achieves the target production f without relying on the intuition of the operator. The purpose is to provide a method for setting the furnace temperature that can be maintained.

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

In general, heating furnaces have a large heat capacity and a large time constant, so controlling the furnace temperature by feedback control has little effect. Therefore, feedforward control that sets the furnace temperature by predicting the furnace condition at a future time from the furnace condition at the current time is effective. Heating material 8□t
In a heating furnace in which fins are present, the furnace temperature is set by following the step -b.

(For the material to be heated S1, the future furnace temperature determined for the materials to be heated 81 to 8i-1 in the furnace on the extraction port side, the current degree of insanity of the material to be heated S1, and this material to be heated. A step of calculating the future furnace temperature for the period in which the heated material 81 will be in the extraction port in the future based on the target extraction temperature of S1 and the scheduled extraction time of the heated materials 81 to 1i1 (D).

(b) If the future furnace temperature calculated in step -) exceeds the specified furnace temperature, the target extraction temperature is obtained at the scheduled extraction time of the material to be heated S1, assuming that the continuous heating furnace is maintained at the specified furnace temperature. The temperature of the material to be heated 81 is calculated in correspondence with time from this scheduled extraction time to the current time, and this temperature is the future furnace temperature determined for the materials to be heated 8□ to 81-凰. The heated material is heated based on! 11, and at time 9, heated material 8□~B1
A step of changing the future furnace temperature determined for -1 to the specified furnace temperature.

First, step i will be explained using FIGS. 1, 2, and 3.

FIG. 2 is a diagram showing the situation in which the slabs S and ~Sn shown in FIG. For the purpose of explanation, 〇 is the current time.Similarly, time jltt is the future time when the slab li reaches the extraction port, and time t
Slab 81 is extracted by 1+1. Also, the interval Δt1 between each time is the extraction pitch), and the extraction pitch t1 is
The time required for post-process rolling, furnace capacity, etc. are determined by the product production volume, etc.

As shown in FIG. 2, the slab S will be at the extraction port from the current time t1 to the future time jlltst, and similarly, the slab li will be at the extraction port from the future time jltt to the future time stt+tt. In this case, by constantly detecting the furnace temperature and measuring the time in the furnace of each slab, the current temperature of all the slabs can be calculated, and then the period during which the slab S1 is in the furnace at the extraction port, that is, tl-1.
This slab 8. It is possible to determine the future furnace temperature that will allow the product to be baked to the target extraction temperature.

If the furnace temperature for 411 hours is determined in this way,
The future temperature of the slab S, ~an (D) at a future time Nts when the slab 81 reaches the extraction port can be calculated,
After that, the period during which the slab 89 is in the furnace at the extraction port, that is, t,
-tl-411 hours this slab 8. It is possible to determine a future furnace temperature that will raise the firing temperature to the target extraction temperature.

Similarly, the future temperature of the slab S1 at a future time *4t1 when the slab Ili reaches the extraction port can be calculated,
The period during which this slab crack is present at the extraction port, that is, ti+
It is possible to calculate the future furnace temperature at which the temperature will reach the target extraction temperature in 1 tim411 hours.

That is, the future furnace temperature determined for the materials to be heated s1 to l1-x located in the furnace closer to the extraction port than the material to be heated B1, the current temperature of the material to be heated 81, and the material to be heated 81
Based on the scheduled extraction time of ~81, the material to be heated 81
It is possible to calculate the future temperature of the furnace during the period when it is in the furnace at the extraction port.

In addition, if the slab 81~5nOIL is currently heated or if it will overflow in the future.
, and the humidity during the period when the furnace is in the extraction port can be calculated using a well-known slab heat transfer model formula. Hereinafter, a method for calculating the furnace m during the period when the slab 8i is in the extraction port will be described using the slab heat transfer model equation.

First, the following equation is used as a model equation regarding slab heat transfer.

ql cy= a-s ((#g-Nk?@)'-(#
v+1? @)') ” (1) #m (jt) work θ-11・jt ・・・・・・・・・・・・・・・ (2) However, the amount of heat absorbed by q varnish slab #g: Furnace Temperature # - Two Slab Current Concentration # Nysteran Amboltzmann Constant: Heat absorption coefficient related to furnace temperature and slab #1()t): is a constant related to the slab temperature after time and the properties and dimensions of the slab.

The above equation (1) is an equation for unsealing heat transfer that expresses the relationship between the furnace temperature θg and the current temperature of the slab -1, and the equation (-) is an equation for calculating the temperature of the slab.

As is clear from equations (1) and (il), by substituting the degree of each slab at the time of charging the slab into the furnace, the detected furnace temperature, and the time in the furnace, all the slabs in the furnace can be
It is possible to know the current temperature of IXL O. Furthermore, if the current temperature of the streak 1-Q, the target extraction humidity, and the extraction pitch are given, the future furnace temperature -ge that will achieve the target extraction temperature can be determined.

Next, 1 slab 9. Regarding, the current humidity, the future furnace temperature determined for Slab Town, and the target extraction of Slab Town 11
By substituting the temperature and extraction pitch into the above equations (1) and (2), the future furnace temperature θg,s that achieves the target extraction temperature of this slab is determined.

Hereinafter, in the same manner, the furnace temperature in the future period (Δtj) when the arbitrary slab 8j in the furnace is in the extraction port trap furnace is determined for the slab 81xsj-1 in the furnace on the extraction port side from the slab aj. The future furnace temperature can be determined from the future furnace temperature, the slag sjo @ lagoon temperature, the target extraction temperature, and each scheduled extraction time of slabs 8 to 811. FIG. 3 shows the future furnace temperature calculated in this manner as a function of time.

Next, Step 3) will be explained using FIG. 3 and Stripe 4.

Future furnace temperature #g, determined by step (&).

When #g・3・°・・0g・1−1 is relatively low, as shown in Fig. 3, for the thick slab S1,
Unless the furnace temperature during the period when the slab S1 is in the extraction port is set to a very high value θg,1, the target extraction temperature may not be achieved. Normally, in a heating furnace, the maximum furnace temperature θgem&X is allowed for operation, #g, i>'gern&
It is clear that in the case of x, the furnace temperature cannot be increased by θg,it, and therefore the slab S1 will be under-fired.

In this way, if it is predicted that there will be a shortage of firing, the maximum furnace temperature θg, which is allowable for operation, will be set as early as 14t1.
Change the maximum storage temperature to n+ax or the maximum storage temperature determined by the slab type, size and pressure (hereinafter referred to as designated temperature), and assume that some slabs in the furnace near the extraction port, such as slab S1, were slightly overcooked. However, it is necessary to minimize the number of overcooked slabs and to obtain the target extraction temperature for the slabs 81. In this way, the timing for changing the future furnace temperature to the designated furnace temperature is determined by the process of step b.

Curve (solid line) A shown in FIG. 4 indicates the extraction time 'JJ tl+1 from the current time t1 of the slag S1, which is predicted to be under-burned.
Curve (dotted line) B shows the predicted temperature trajectory until the target extraction temperature θs + i r any at the scheduled extraction time ti+ 1 of the slab S1, assuming that the furnace temperature is maintained at the specified temperature.
The temperature of the slab 81 is calculated as a function of time from the scheduled extraction time t1+1 to the current time t1 in order to obtain the temperature of the slab 81.

Normally, the temperature of the slab S1 is the temperature J18 as shown in curve A.
1' and rises, but the song %lB is a trajectory that starts from the target extraction humidity and releases heat from future time 1° to current time 1°. in this way,
The temperature of the slab, which decreases while emitting heat, can be easily calculated by changing the right side of the above equation (Z) from addition to subtraction. That is, the following equation may be used instead of equation (2).

14″′・θS(Δt)=θB−1・Δt ・・・・・・・・・(
3) Thus, as is clear from FIG.
In order to explain the target extraction 6 and 11 degrees, curve A and song i
Time tA when aB intersects with aB! In step 1, L (determined) will be sufficient to change the future furnace temperature to the specified furnace temperature.

That is, as shown in FIG. 5, from the current time Ntt to the future time tii+1, the determined furnace temperature is set sequentially starting from the slab closest to the extraction port, and from time tie to the time mti+□ when slab B1 is extracted, the furnace temperature is set as described above. If you set the specified furnace temperature,
The number of overcooked slabs can be suppressed to a minimum, and the slabs 81 can be baked to the target extraction temperature.

As described above, by carrying out the process of step &lb, it is possible to accurately determine the future furnace temperature at which all the slabs in the furnace will be baked to the target extraction temperature.

Next, FIG. 6 is a block diagram showing the configuration of a temperature setting device that implements the temperature setting method according to the present invention, and 11 in the figure is an extraction pitch calculation that calculates the scheduled extraction time of all slabs in the furnace according to the subsequent process. The device, Ebisu, is a slab temperature control device that calculates the current temperature of all slabs from the time when the material to be heated is charged into the heating furnace. The future furnace temperature calculation device 14 that calculates the furnace temperature executes the process of step b above, and when the future furnace temperature calculated by the future furnace temperature calculation device 13 cannot be realized, the furnace temperature determined in advance (designated A furnace temperature change timing calculation device 16 determines the timing for changing the future furnace temperature to a specified furnace temperature based on data in a furnace temperature table 15 that stores the furnace temperature (furnace temperature); A storage device 17 stores the temperature and time determined by the furnace temperature change tie calculation device 14, and 17 represents an output device that sets the furnace temperature in the heating furnace 18 based on the values stored in the storage device 16.

In FIG. 6, on the left, an extraction signal for extracting the material to be heated or a signal generated at fixed time intervals is applied as a starting signal G to the extraction pitch calculation device 11 and the slab temperature performance device 12. The extraction pitch of all the slabs is calculated according to the type of furnace and the missing time, while the slab temperature performance device 12 calculates the current temperature of all the slabs based on the detected furnace temperature and the furnace time of the valley slab.

By the way, the future 5P temperature calculation device 13 is the extraction pitch calculation device 1.
1 and No. i6 of the slab humidity calculation device 12, and
Based on the target extraction temperature of each slab, first determine the future furnace temperature for the period that the slab will be in the furnace at the extraction port, and then determine the future furnace temperature for the period that the subsequent slab will be in the furnace at the extraction port in the future. The future furnace temperature will be determined sequentially. In this case, the future furnace temperature during the period when the slab 81 is in the extraction port is determined by the current temperature of the slag 81, the target extraction temperature of the slab 81, and the scheduled extraction time of the slab S1. The future furnace temperature during the furnace period is determined for the slab 81 based on the future furnace temperature, the current temperature of slab 8%, the target extraction temperature of slab S-, and the scheduled extraction time of slab J* 8g. Thereafter, the future furnace temperatures of all slabs are determined in the same manner.

On the other hand, the furnace temperature change timing calculation device 14 calculates the temperature when the furnace temperature calculated by the furnace temperature calculation device B cannot be achieved in the future (including cases where the maximum temperature is limited depending on the type of slab even if the heating furnace itself has the capability). ), 11 Assuming that the heating furnace is maintained at a specified furnace temperature, the temperature of the slab 81 is adjusted according to time from this scheduled extraction time to the current time so that the target extraction temperature is obtained at the scheduled extraction time of the slab 81. This temperature is the slag S, ~8i-
A time signal of a time interval 4 r tin corresponding to the temperature of the slab S1 to be heated based on the nine future furnace temperatures determined for 1 and the designated furnace temperature signal of the furnace temperature table 15 is added to the storage device 16 .

The storage device 16 stores the future furnace temperature of the future furnace temperature calculation device U and the specified furnace temperature of the furnace temperature change timing calculation device 14, and the output device 17 stores the future furnace temperature of the future furnace temperature calculation device U and the designated furnace temperature of the furnace temperature change timing calculation device 14, and the output device 17 stores the future furnace temperature of the future furnace temperature calculation device U and the specified furnace temperature of the furnace temperature change timing calculation device 14.
The heating furnace 18
Set the furnace temperature to .

Thus, by the furnace temperature setting device shown in FIG.

The processes of steps a and b of the present invention can be performed.

As is clear from the above explanation, according to the method for setting the furnace temperature of a continuous heating furnace of the present invention, the furnace temperature is set to 8 to ensure the minimum target extraction temperature required in the subsequent process for each slab in the furnace. It is possible to make precise settings, ensure the stability of the entire twin operation including post-processing, and keep energy consumption to a minimum.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the arrangement of the material to be heated in a continuous heating furnace to which the furnace temperature setting method of the present invention is applied, and FIG. 2 is an explanatory diagram showing changes in the arrangement of the material to be heated. Figures 3, 4, and 5 are diagrams showing the relationship between time and '4 current to explain the furnace temperature setting method of the present invention, and Figure 6 is a diagram showing the relationship between the furnace temperature setting method of the present invention. It is a block diagram showing the composition of the furnace temperature setting device implemented. l... Continuous heating furnace, 2... Burner, 131~an/
・Material to be heated, 11-・Extraction pitch calculation device, 12・
...Slag temperature calculation device, 13... Future furnace temperature calculation device, 14... Furnace temperature change timing calculation device, b... Furnace temperature table, 16... Storage device, 17... Output device, 18.--Continuous heating furnace. Applicant's agent Kiyoshi Inomata Figure 2

Claims (1)

[Claims] 1. Material to be heated 81°81 from the extraction port to the charging port
．． ..., 81. ..., In the furnace temperature setting method for a continuous heating furnace in which In is located, the future furnace temperature determined for the heated materials 111 to 111-□ located in the furnace on the sea extraction port side , the current temperature of the heated material s1, the target extraction temperature of this heated material 81, and the heated material 8□~
81. A furnace S setting method for a continuous heating furnace, characterized in that the furnace temperature during the period when the material to be heated 81 is in the extraction port is calculated based on the scheduled extraction time of 81. 2. Material to be heated 8□ from the extraction port to the charging port. 81,...g jli* In the continuous heating furnace 0FiJA setting method where Bn is in the furnace, the material to be heated B1 is also determined for the materials to be heated 81 to J'1-IK which are in the furnace on the extraction port side. Future furnace temperature, current temperature of heated material 8i,
The target extraction humidity of the heated material 81 and the heated material 8□
~ StO extraction scheduled time, calculate the furnace temperature during the period when the material to be heated S1 is in the extraction port, and if this future furnace temperature exceeds the estimated furnace temperature, the continuous heating furnace is set to the designated furnace temperature. The temperature of the material to be heated 81 is calculated in correspondence with time from the scheduled extraction time of kernels to the current time so that the target extraction If is obtained at the scheduled extraction time of the material to be heated 11o. , when the temperature of the heated material 81 to 51 matches the temperature of the heated material 81 to be heated based on the future furnace temperature determined for the heated material 81 to 81-1.
A furnace temperature setting method for a continuous heating furnace characterized by changing a future furnace temperature determined for −0 to a specified furnace temperature.