JPS5814856B2 - Heating furnace control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling an industrial multi-zone heating furnace.

General ζHot rolling line with industrial multi-zone heating furnace O
Here, the furnace extraction rate of the steel billet is not constant.

In other words, statistically speaking, the extraction rate of steel slabs is constant, but when observed microscopically, the extraction rates of individual steel slabs during heating furnace operation are all different, and the extraction rate during heating furnace operation is different. There are line troubles, setup changes such as roll changes, and other machine stoppages, which are also factors that disturb the extraction speed of steel pieces.

Furthermore, in the case of manual furnace operation, it is difficult to make appropriate changes to the furnace vortex in response to changes in furnace operating conditions. As a result, the core steel pieces are made to rise more than necessary.

On the other hand, if the extraction speed is faster than the standard extraction speed, the steel billet will be burned, and for example, in the case of a round steel billet in a pipe manufacturing line, the uniformity of heat will deteriorate, resulting in twisting or uneven thickness during drilling. There was a problem in that this caused a negative impact on the quality of the product.

The present invention aims to provide a method for controlling the temperature of a heating furnace in order to avoid the various adverse phenomena caused by disturbances in the extraction rate of steel billets as described above (and to reduce the fuel consumption rate). Hereinafter, the method of the present invention will be explained in detail.

First, in consideration of the heating furnace specifications, the temperature increase pattern of the target material is determined in advance by the flowchart shown in FIG. Flowchart 1-6 for determining the furnace vortex TV to follow.

Note that this temperature increase heat pattern applies to the steel type of the general steel billet.
It is determined empirically for each dimension.

In other words, the basic principle of the control method of the present invention is to use the predetermined vortex heating heat pattern of the target material as a reference 6 and to adjust the furnace plate to follow the heating heat pattern even if the extraction rate ζ varies. is to set.

In other words, the furnace humidity should be adjusted according to the vortex heat pattern of the target material. ■
The aim is to reduce the unit fuel consumption by increasing the amount of fuel.

(Here, the target material's heating pattern is the target vorticity θi (i is the number of each band) of the steel slab on each band exit side of the heating furnace.
Figure 1 shows, as an example, the heating pattern of a round steel piece in a three-zone heating furnace.

In addition, in FIG. 1, the temperature increase state between each zone is shown by a straight line for the sake of simplicity.

Next, the furnace temperature Tvi is determined for each zone so that the material temperature follows the temperature increase heat pattern ζ of the target material described above.

That is, as shown in the flowchart in Fig. 2, when an arbitrary extraction speed ■ is given to the material, the residence time ΔL1 in the first zone is Δti2Li/V ・・・・・・・・・■Tax, L12 The length of each zone (thus calculated, and assuming that the material temperature at the time of loading has reached the target material temperature in the (i-1')th zone, the material fullness is θl−1, and if the temperature Tvi in the first zone is given as the material ζ,
The material temperature θ'l after ΔL time in equation (2) is calculated by the temperature calculation method shown in equation (2).

(2) Overall heat transfer coefficient ρ determined by the heating furnace model, etc. (2) Material density C (2) Material specific heat h: Material dimension △ [: Time interval Here, material vorticity θ'i calculated from equation (2) Q When is equal to the target material temperature θ■ in the first zone, this is the furnace mixture Tvi for the desired extraction rate ■.

If the calculated material mixture θ'1 is not equal to the target material vorticity θ1, the same material temperature calculation as above is performed after correcting the furnace temperature Tvi, and the calculated material temperature θ'1 after △L time is the target. {
Repeat until the vorticity becomes equal to O's vorticity θ1.

In other words, by performing the above-mentioned operations, the furnace vortex TV corresponding to a certain extraction rate ■ζ is uniquely determined.

From the above method Q, the extraction rate ■ is varied from 0 to infinity and the furnace temperature Tvi is calculated for each zone. A relationship diagram with M T v (hereinafter referred to as 'FTv-'V diagram) is obtained, and this Tv-V diagram is created for all bands and also for all steel types and dimensions.

FIG. 3 shows a Tv line diagram in an embodiment similar to that in FIG. 1.

From the above-mentioned dimension ζ, all steel types, T v with dimension ζ
- After obtaining the V diagram, set and output the furnace vortex Tvi based on the flowchart shown in Figure 4. For example, in the case of a rotary hearth furnace, by detecting the momentary rotation angle C and its time L. The hearth moving speed is equal to the material extraction speed Vζ, where K: constant Q.

Next, it is determined whether the steel type and size of the materials existing in the first zone are the same steel type and size.

If only the same steel heel and dimensions exist within the first zone, the Tv-V diagram corresponding to the steel type and dimensions within the zone is searched and determined.

After that, the extraction speed V at this time is determined from the corresponding Tv-V diagram.
6, the corresponding furnace vortex Tvi of the first zone is read, and the corresponding furnace vortex T
VI is output as the setting output Tsi.

In addition, if there are materials with different steel types and dimensions in the first zone, the material will match the steel types and dimensions with higher priority, which will be described later, from among all the steel types and dimensions of the materials present in the zone. Search and determine the Tv-V diagram, and from this Tv-V diagram,
The furnace vortex TvI of the belt is read and outputted as the set output Tsi.

By performing the above-mentioned operation for the entire zone, the furnace vortex T in the heating furnace can be controlled optimally.

The priority order of steel types and dimensions is generally determined empirically in each manufacturing process, and the determining conditions include, for example, steel materials such as stainless steel, which are most sensitive to heating conditions. This decision is made to avoid underheating or overheating things.

That is, the control method of the present invention is applied when the heating capacity of the heating furnace exceeds the rolling speed (2).

This is because each heating furnace has its own heating capacity, and the maximum furnace temperature setting value Tsmax of each heating furnace is limited according to the heating capacity, and it is not possible to set a value higher than the setting value Tsmax. It is.

In other words, even if the maximum extraction speed Vmax of a certain heating furnace is exceeded, the furnace temperature Tv can be determined from the Tv line diagram.
Based on the heating capacity of the heating furnace, the maximum furnace temperature setting value Tsm of the heating furnace is determined.
This is because ax is limited, so it is not possible to set and output Tsi and Tvi.

As described above, according to the control method of the present invention, the furnace temperature setting for the extraction rate is optimally controlled in response to the momentary changes in the extraction rate of each zone in the heating furnace. This invention has the effect of not only being able to maintain optimal material saturation even in the face of fluctuations, preventing product defects, but also reducing fuel consumption.

Chinami Q: φ180×4000l, φ with a 3-zone 2 rotary furnace for somless pipe making with a heating capacity of 100 TON/HOUR.
Figure 5 shows the extraction temperature and the hiss I/Durham of the uneven heat of the extraction when carbon steel materials of 170 x 350 M and φ 160 x 3000 l are mixed and heated.

Figure 5A shows the situation when the heating furnace is operated manually, and the opening of the figure shows the situation when the heating furnace is operated according to the method ζ of the present invention.

As is clear from the figure, by using the method of the present invention, the variation in the degree of extraction is reduced by half, which in turn contributes to improving the quality of the product.

In addition, the fuel consumption rate in this example Q is 4 when the reactor is operated manually.
6. 9 X 1 0' Kcal/ton, whereas when the control of the present invention is implemented, it is 44.6 X 1 0' Kcal/ton.
It was cal/ton.

[Brief explanation of the drawing]

FIG. 1 shows a heating pattern for one embodiment of a three-zone heating furnace, FIG. 2 is a flowchart for setting the furnace temperature in the sixth embodiment of the present invention, and FIG. 3 is a similar embodiment to FIG. 1. (
FIG. 4 is a flowchart for implementing the method of the present invention in a rotary hearth furnace Q;
Figure 5 shows a histogram of extraction depth and uneven heat when three types of materials are mixed and heated in a three-zone two-rotary hearth furnace. This is a case of control.

Claims (1)

[Claims] 1 In an industrial multi-zone heating furnace, the temperature increase pattern of the target material is determined in advance, and the content of the material to be heated is constantly calculated using the general temperature calculation method C, and the humidity of the material and the target temperature increase pattern are calculated. In the method of determining and outputting the furnace vortices for each zone so that they are equal, the relationship Tv-'V diagram of the furnace vortex Tv that makes the material temperature follow the above-mentioned target temperature increase pattern is varied depending on the material extraction rate V4. The steel type and dimensions (determined in advance and the actual or predicted extraction rate) are determined using the Tv-V diagram of the high-priority material determined according to the steel type and dimensions in the heating furnace zone. A heating furnace control method characterized by determining and calculating and controlling the furnace temperature.