JPH0232329B2 - KANETSUROSEIGYOHOHO - Google Patents

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 only one billet conveying device for the entire furnace, and 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 can be cast without being completely cooled.
Rolling began to be performed by charging directly into rolling equipment.

In this case, problems arise such as mismatch between continuous casting speed and rolling speed and securing the optimum steel material temperature for rolling. To solve this problem, there is a method in which combustion is controlled by installing a heating furnace between the continuous casting equipment and the rolling equipment, which can transport billets independently for each combustion zone.

This type of heating furnace accepts steel billets from slow continuous casting into the first zone on the charging side, one for each charge, and when charging is finished, transfers the billets between each combustion zone for each charge. Perform combustion heating while heating.

Conventional combustion control for continuous heating furnaces is based on the assumption that the billet moves continuously, so it is necessary to use a temperature increase pattern calculated in advance using separate calculations based on the average billet movement speed and extraction target temperature. It was possible to control combustion based on time. However, in a furnace that moves discontinuously in charge units, such as the one targeted by the present invention, the conventional assumption of continuous movement no longer holds true, and it is necessary to calculate the temperature increase pattern while recognizing the operating state in real time.

An object of the present invention is to provide a combustion control method for a continuous heating furnace in which steel can be transported independently for each combustion zone, which can calculate a temperature increase pattern in real time and thereby contribute to energy saving. It is in.

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 the above problems, the present invention sets a representative steel billet in the charge, calculates the temperature increase pattern only for the representative billet, and then calculates the temperature increase pattern of the other steel billets in the charge. We have discovered a combustion control method for a heating furnace that can contribute to energy savings by determining it from temperature patterns, and have now completed the present invention.

That is, the present invention is a continuous heating furnace that heats a plurality of units of steel slabs (hereinafter referred to as charges) while moving them, and that is capable of conveying steel slabs independently for each combustion zone. In the method of controlling the combustion of The combustion control method for a heating furnace is characterized in that the combustion in the heating furnace is controlled by determining the current temperature ratio and the scheduled time ratio until extraction from the heating furnace.

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

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

θ _EX indicates the extraction target temperature, θ ₀ is the current temperature of the representative billet, θ ₁ is the current temperature of the non-representative billet, t ₀ is the scheduled time until extraction of the representative billet, t ₁ is the non-representative billet. Indicates the estimated time until extraction of the steel billet.

First, the temperature is normalized by the extraction target temperature, and a=θ ₀ /θ _EX ...(1) b=θ ₁ /θ _EX ...(2).

Next, the current temperature ratio and scheduled time ratio until extraction of the representative steel piece and the non-representative steel piece are defined, and ξ=b/a...(3) = _t1 / _t0 ...(4).

Representative billet temperature rise pattern 3 normalized to Figure 2.
A non-representative steel billet temperature increase pattern 4 is shown.

Figure 3 shows the conversion coefficient from the typical steel billet temperature increase pattern to the non-representative steel billet temperature increase pattern, and is expressed as c(τ) = (1-ξ)τ/+ξ...(5).

here τ＝t……(6) It is.

From the above, if the normalized temperature increase pattern of the representative steel piece is θ ₀ (t) / θ ₀ = f ₀ (t) ...(7), then the normalized temperature increase pattern of the non-representative steel piece is θ ₁ (τ) /θ ₁ =f ₁ (τ) =c(τ)f ₀ (t) =c(τ)f ₀ (τ/) ...(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, both differences are small, and a sufficient approximation can be obtained.

The number of billets from continuous casting equipment is usually around ten per charge. First, the temperature increase pattern of the central steel billet in the charge is calculated, and then the temperature increase pattern of the other steel billets in the charge is determined from equation (8).

According to the present invention, by determining the temperature increase pattern for only one representative steel billet within one charge, it is possible to determine a sufficiently accurate temperature increase pattern for all the steel billets within the charge, resulting in excessive computer load. Therefore, it has become possible to calculate the temperature rise pattern of all steel slabs in real time using a control computer, etc., which was previously impossible. Furthermore, this makes it 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 drawings]

The drawings show an example of the present invention. Figure 1 is a temperature increase pattern diagram of a representative steel billet and a non-representative steel billet, and Figure 2 is a diagram of the temperature increase normalized by the extraction temperature of a representative steel billet and a non-representative steel billet. The pattern diagram and FIG. 3 are conversion coefficient diagrams from representative steel pieces to non-representative steel pieces. 1...Representative steel billet temperature increase pattern, 2...Non-representative steel billet temperature increase pattern, 3...Representative steel billet normalized temperature increase pattern, 4...Non-representative steel billet normalized temperature increase pattern.

Claims (1)

[Claims] 1 Controlling the combustion of a continuous heating furnace, which is a heating furnace that heats a plurality of units of steel slabs (hereinafter referred to as charges) while moving them, and is capable of conveying steel slabs independently for each combustion zone. In the method of A combustion control method for a heating furnace, characterized in that the combustion in the heating furnace is controlled by determining from the scheduled time ratio until extraction from the heating furnace.