JPS59145736A - Method for controlling heating furnace - Google Patents

Abstract

PURPOSE:To perform combustion control for minimizing fuel consumption by setting a representative billet in a charge, calculating the temp. raising pattern to obtain that of other billets based on this calculation result in a continuous heating furnace. CONSTITUTION:In the fuel control of the continuous heating furnace carrying and treating the billet independently at every combustion zone, the representative billet is set at the every charge to calculate the temp. raising pattern. Based on this calculated result, the temp. raising pattern of other billets is calculated from the present time temp. ratio of the representative billet to the other billets and the expected time ratio necessary for extracting from the heating furnace. By this controlling system, the temp. raising pattern of high precision can be obtained for all billets in the charge, and the contribution to energy saving can be attained.

Description

[Detailed description of the invention] The present invention relates to a combustion control method for a heating furnace.

A conventional continuous billet heating furnace has a single billet conveying device for the entire furnace, and all the billets are conveyed simultaneously from the charging side to the extraction side at the same speed. In recent years, with the spread of continuous casting equipment, continuous casting materials have come to be directly charged into rolling equipment and rolled without being completely cooled.

In this case, it is a problem to ensure the optimum temperature of the steel material for rolling due to the mismatch between the continuous casting speed and the rolling speed. In order to solve this problem, there is a method of controlling combustion by installing heating furnaces that can independently transport billets in each combustion zone at the continuous casting facility, rolling facility, and processing facility.

This type of heating furnace accepts steel billets from slow continuous casting one by one into the first zone on the charging side, and when charging is finished, the billets are transferred between each combustion zone in charge units. Combustion heating is performed while

Conventional combustion control in continuous heating furnaces is based on the assumption that the billets move continuously, so the temperature increase pattern / Using this, we were able to perform real-time combustion control. However, in a furnace that moves discontinuously in units of charges, such as the subject of the invention, the conventional assumption of continuous movement does not hold true, and it becomes necessary to calculate the temperature increase pattern without fully recognizing the operating state in real time.

The purpose of the present invention is to provide a combustion control method for a continuous heating furnace in which steel slabs can be conveyed independently for each combustion zone, which can contribute to energy saving by calculating the heating temperature of butter in real time. It is about providing.

The temperature rise pattern of a steel billet can be found by linearizing the fuel minimization problem for each combustion furnace zone using the extraction temperature as a constraint and using a linear programming method, but this requires a very large amount of calculation in real time. It is difficult to calculate temperature rise patterns for all steel materials using current general control computers. In order to solve all of the above problems, the present invention sets a representative piece of steel in the charge, calculates the temperature increase pattern only for the representative piece, and then calculates the temperature increase pattern of the other hook pieces in the charge. By searching for warm butter, we have discovered a combustion control method for a heating furnace that can contribute to energy savings, and have now completed the present invention.

That is, the present invention is a heating furnace that heats a plurality of reeds and one unit (hereinafter referred to as a charge) of steel pieces while moving them, and is a continuous type furnace that can transport all the steel pieces independently for each combustion zone. In the method of controlling combustion in a heating furnace, a representative piece of steel is set for each charge, and other temperature rising patterns are calculated based on the calculation results of the temperature rise pattern of the representative piece of steel and the other pieces of steel. The combustion control method for a heating furnace is characterized in that the combustion amount of the heating furnace is determined based on the current temperature ratio with respect to a steel billet and the scheduled time ratio at 1 extracted from the heating furnace.

Hereinafter, a method of calculating the temperature increase pattern of other steel slabs (hereinafter referred to as non-representative steel slabs) from the temperature increase pattern of the representative steel slab in the non-invention will be explained.

FIG. 1 shows the temperature increase pattern of representative steel piece 1 and the temperature increase pattern of non-representative steel piece 2.

θEX indicates the extraction target temperature, and θ. is the current temperature of the representative steel billet, θ is the current temperature of the non-representative steel billet, 1o is the scheduled time until extraction of the representative steel billet, and tl is the scheduled time until extraction of the non-representative steel billet.

First, the temperature is normalized by the total extraction target temperature, and a=θ. /
θΣE・・・・・・・・・・・・・・・(υb=θ1
/θΣX・・・・・・・・・・・・C2).

Next, define the current temperature ratio of the representative slab and the non-substituted slab and the scheduled/scheduled time ratio until extraction, ξ= b / a ・・・・・・・・・・・・・・・
・・・・・・(3) ψ=t, /lo ・・・・・・・・・
...(4) 1.

FIG. 2 shows the normalized typical steel billet temperature increase pattern I, turn 3, and non-representative steel billet temperature increase pattern 4.

Figure 3 shows the conversion coefficient to the temperature rise pattern of a representative steel piece and the temperature rise pattern of a non-representative steel piece.
+ ξ ・・・・・・・・・ (5) ψ is n.

Here, T=ψ1 (6).

From the above, the normalized temperature increase turn of the representative steel piece is θ0 (s/θ. = fo(ri)
7), the normalized temperature rise of the non-representative steel piece (the turn is θ
1 (τ)/θ1”fl(s=c(sf.(rini c(r)fo(r/ψ)) It can be determined by (8).

Equation (5) above linearly interpolates the difference between the current temperature difference and the expected time until extraction, and for steel pieces in the same charge, the difference in n is always small, and a sufficient approximation can be obtained.

The number of billets from continuous casting equipment is usually a few pieces per charge. First, calculate the temperature rise/jitter/ of the central piece of steel in the charge, then calculate the temperature rise pattern of the other pieces of steel in the charge (
8) Calculate from formula.

According to the present invention, by determining the temperature increase pattern for only one representative piece of steel within one charge, it is possible to obtain sufficiently accurate temperature rise butter 7 for all the steel pieces in the charge, and the computer load is reduced. It has now become possible to calculate the temperature rise and turn of the entire steel billet in real time using a control computer, etc., which was previously impossible due to the excessive size. Furthermore, it has been possible to provide a combustion control system for a heating furnace that can minimize the amount of fuel used, that is, can contribute to energy savings.

[Brief explanation of the drawing]

The drawings show the implementation of the present invention. Figure 1 is a temperature rise pattern diagram of a representative steel piece and a non-representative steel piece, and Figure 2 is a diagram normalized by the extraction temperature of a representative copper piece and a non-representative steel piece. The temperature increase pattern diagram, Figure 3, is a diagram showing the conversion coefficient from a representative steel piece to a non-representative steel piece. 1... Representative steel billet temperature increase pattern, 2... Non-representative steel billet temperature increase pattern, 3... Representative steel billet normalized temperature increase pattern, 4
Figure 1 Figure 3 Continued from page 1 0 Inventor Yutaka Tokunaga - 5-2-1 Hitachi Daimikacho 5-2-1 Hitachi Ltd. Inumika Factory Inventor Jira Kumayama 5-2-1 Hitachi Daimikacho Name: Hitachi, Ltd., Omika Factory @Applicant: Hitachi, Ltd., 5-1 Marunouchi-chome, Chiyoda-ku, Tokyo

Claims (1)

[Claims] 1. A heating furnace that heats multiple units of steel slabs (hereinafter referred to as charges) while moving them all, and that is a continuous heating furnace that can transport all the steel slabs independently for each combustion zone. In the control method, a representative billet is set for each charge, and other temperature increase patterns are determined based on the temperature rise butter/calculation results of the representative billet and the current temperature of the representative billet and other billets. A combustion control method for a heating furnace, in which combustion in the heating furnace is determined based on a temperature ratio and a scheduled time ratio until extraction from the heating furnace.