JP2006274421A - Combustion control method of continuous heating furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the combustion control method of a continuous heating furnace adaptable to the change of an operational mode of a hot rolling equipment. <P>SOLUTION: In the combustion control method of the continuous heating furnace, firstly, the temperature rise of a work to be rolled in a soaking zone is determined in accordance with the operational mode of hot rolling equipment. Secondly, the furnace temperature in the soaking zone is determined by the determined temperature rise of the work in the soaking zone and the in-furnace time of the work. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a combustion in a continuous heating furnace in which the material to be rolled in the furnace is sequentially conveyed from the charging side to the extraction side, heated in a heating zone by a heating amount, and then in a soaking zone, soaking by a heating amount. It relates to a control method.

  In order to continuously supply a heated material to be rolled to a rolling mill of a hot rolling facility, a continuous heating furnace having a heating zone and a soaking zone is generally used. In such a continuous heating furnace, fuel is burned while controlling the amount of combustion, and the materials to be sequentially conveyed are heated in the heating zone by the temperature rise amount, and then in the soaking zone, the temperature rises by the temperature rise amount. Combustion control is performed in a continuous heating furnace that raises the temperature of the rolled material from the charging temperature to the extraction target temperature.

  In recent years, a continuous heating furnace equipped with a walking beam apparatus has been installed in a hot rolling line as a furnace capable of producing a hot-rolled steel sheet having high heating capacity and excellent surface quality (Patent Document 1). As shown in FIG. 5, the continuous heating furnace described in Patent Document 1 includes a driving mechanism in which the walking beam device is divided into at least two parts in the conveying direction of the steel piece S and can be driven independently. The furnace body 1 includes a transfer device 3 for transferring the steel piece S between the walking beams 2. In FIG. 5, reference numeral 4 denotes a temperature calculation device for calculating the furnace temperature of each zone from the fuel flow rate. Further, 5 is an interval calculation device that determines the interval of the steel slabs S on each walking beam 2 from information such as the charging pitch, the extraction pitch, the temperature of the steel slab S and the furnace temperature, and 6 is the amount of movement of each walking beam 2. 7 is a tracking device for determining the position of the steel piece S on the basis of the moving amount of each walking beam 2, and 9 is a transfer position control device for controlling the position of the transfer device 3. .

In this continuous heating furnace, a charging detector 11 for measuring the charging pitch of the steel slab S into the furnace and a thermometer 13 for detecting the temperature of the charging slab are installed in the vicinity of the charging door 3A. An extraction detector 12 for measuring the extraction pitch is provided in the vicinity of the extraction door 3B.
In the continuous heating furnace for heating the steel slab, the steel slab S is formed between the strips for the purpose of improving the heating accuracy of the steel slab S and reducing the heat loss with respect to the charging of the hot slab. Is made variable by the billet temperature, the combustion amount of fuel, the extraction pitch, and the charging pitch, so that the billet conveyance speed on the walking beam 2 is controlled.

Recently, there is an increasing demand for improving the rolling efficiency of a hot rolling facility equipped with a continuous heating furnace, and it is necessary to operate the furnace in response to the change in the operation mode of such a hot rolling facility. .
Here, in a continuous heating furnace installed in a hot rolling facility, the furnace temperature of each belt is usually determined by calculation using a computer, and the determined furnace temperature is stored as a set value in the computer, and the continuous heating furnace The combustion control is executed.
JP-A 61-279615

However, the conventional combustion control of continuous heating furnaces reduces the fuel consumption rate, which accounts for a large proportion of the running cost, so consider the temperature rise of the rolled material in the soaking zone on the side where the rolled material is extracted. However, it was possible to operate the furnace only with the latter high-load heat pattern.
For this reason, for example, even if it is desired to prioritize the rolling efficiency over the basic unit of fuel, in the continuous heating furnace installed in the hot rolling facility, such an operation setting is not made, and the operation mode of the hot rolling facility is not Since it was able to cope with the change, the combustion control usage rate of the continuous heating furnace using a computer was low.

  It is an object of the present invention to provide a combustion control method for a continuous heating furnace that can solve the problems of the prior art and can cope with changes in the operation mode of hot rolling equipment.

The present inventor has intensively studied the reason why the combustion control usage rate of the continuous heating furnace using a computer is low, and as a result, the temperature drop of the skid mark part with respect to the steady part has an adverse effect on the plate passing property. Thus, the present inventors have found that the rolling efficiency may be hindered.
The present invention is as follows.
1. In the combustion control method of a continuous heating furnace in which the material to be rolled in the furnace is sequentially conveyed from the charging side to the extraction side, heated by the heating temperature in the heating zone, and then heated by the temperature increase in the soaking zone. First, the temperature increase amount of the material to be rolled in the soaking zone is determined in accordance with the operation mode of the hot rolling facility, and then the furnace temperature in the soaking zone is set to the determined temperature rise of the material to be rolled in the soaking zone. A combustion control method for a continuous heating furnace, characterized in that it is determined from the amount of heat and the in-furnace time of the material to be rolled.
2. The temperature increase amount of the material to be rolled in the soaking zone is determined in consideration of a relationship with an influence factor that enables the material to be rolled to be stably rolled, which is obtained by analyzing in advance. The combustion control method of the continuous heating furnace as described in 1.
3. The influential factor that enables stable rolling of the material to be rolled is defined as a temperature drop amount of the skid mark portion with respect to the steady portion when the temperature of the material to be rolled reaches the extraction target temperature. Item 3. A combustion control method for a continuous heating furnace according to Item 2.

  According to the present invention, in response to a change in the operation mode of the hot rolling facility, the latter-stage high-load heat pattern in which the temperature rise of the material to be rolled is increased in the soaking zone with priority on the fuel intensity. It is possible to heat the material to be rolled at the same time, or in response to changes in the operation mode of the hot rolling equipment, the temperature rise of the material to be rolled in the soaking zone with priority on rolling efficiency is reduced. It is also possible to heat the material to be rolled with a subsequent low load type heat pattern.

  According to the combustion control method for a continuous heating furnace according to the present invention, the combustion control usage rate of the continuous heating furnace using a computer can be increased.

Hereinafter, the case where this invention is applied to the continuous heating furnace which heats the steel piece S is demonstrated.
In FIG. 1, the structure of the continuous heating furnace which has the heating zone and soaking zone to which this invention is applied was shown typically. In FIG. 1, θ _1,1 indicates the furnace temperature in the first heating zone, θ _1,2 indicates the furnace temperature in the second heating zone, and θ ₂ indicates the soaking zone furnace temperature. The furnace temperatures θ _1,1 , θ ₁ , ₂ , and θ ₂ are determined by calculation using a furnace operating computer (not shown).

The continuous heating furnace for heating the steel slab S has a first heating zone and a second heating zone as heating zones in order to continuously supply the steel slab heated to a predetermined temperature to the hot rolling mill. Moreover, the furnace body 1 is provided with a walking beam device, and the steel beam S in the furnace charged in the heating zone from the charging door 3A is sequentially conveyed from the charging side to the extraction side by the walking beam 2 of each band. It is configured.
At that time, a computer for operating the furnace (not shown) heats the steel slabs S that are sequentially transported by the heating amount in the heating zone, and then heats the steel slab S by the temperature increase in the soaking zone. Combustion control of a continuous heating furnace that increases the temperature T _in to the extraction target temperature T _out is performed.

Hereinafter, a method for determining the furnace temperatures θ _1,1 , θ ₁ , ₂ , and θ ₂ will be described in order (see FIG. 3).
Here, the temperature rise amount of up are extracted from contains steel slab S to the soaking zone (i.e., that temperature Yutakaryou billet S in soaking zone) a When [Delta] T _2, the steel strip in soaking zone S Is a model of a two-dimensional heat transfer difference using the ADI method, based on the relationship (S11) between the temperature rise amount ΔT ₂ and the in-furnace time (time from charging the steel slab S to the heating furnace until extraction) The soaking zone furnace temperature θ ₂ can be determined (S12).

The remaining furnace temperatures θ _1,1 of the first heating zone and furnace temperatures θ _1,2 of the second heating zone are determined as follows (S13 to S16).
Assuming that the temperature rise amount of the steel slab S in the first and second heating zones is ΔT _1,1 and ΔT _1,2 , respectively, the amount of temperature rise of the steel slab S during the in-furnace time is T _out −T _Since it is equal to in, the total temperature rise amount (ΔT _1,1 + ΔT _1,2 ) of the steel slab S in the first and second heating zones is obtained from the equation (1).

ΔT _1,1 + ΔT _1,2 + ΔT ₂ = T _out −T _in (1)
And the temperature increase amount ΔT _1,1 , ΔT ₁ , ₂ of the steel slab S in the first and second heating zones is the ratio of the temperature increase between the first heating zone and the second heating zone from the heating capacity of each zone. Since ΔT _1,2 / ΔT _1,1 (= k: constant value) is determined, it can be calculated.
If the heating rate ΔT _1,1 of the steel slab S in the first heating zone is obtained, the two-dimensional transmission using the ADI method is performed based on the first heating zone heating rate and the first heating zone furnace time. The furnace temperature θ _1,1 of the first heating zone can be determined by the model of the thermal difference. Similarly, if the temperature increase ΔT _{1, 2} of the steel slab S in the second heating zone is obtained, the ADI method is used based on the second heating zone temperature increase and the second heating zone in-furnace time. The furnace temperature θ ₁ , ₂ of the second heating zone can be determined using a two-dimensional heat transfer difference model.

However, the temperature rise ΔT _{2 of the} material to be rolled in the soaking zone is determined in consideration of the relationship with the influence factor that enables the steel slab S obtained by analysis in advance to be stably rolled. For example, as shown in FIG. 2, when the temperature of the steel slab S reaches the extraction target temperature, the temperature drop amount of the skid mark portion relative to the steady portion and the temperature rise amount ΔT _{2 of the} material to be rolled in the soaking zone In consideration of the relationship, the temperature rise ΔT _{2 of the} material to be rolled in the soaking zone is determined.

FIG. 2 shows various changes in the temperature rise of the steel slab S in the soaking zone in the continuous heating furnace for heating the steel slab S, and when the temperature of the steel slab S reaches the extraction target temperature _Tout , It is the result obtained by extracting the steel slab S from the heating furnace to the hot rolling line and measuring its temperature.
At that time, when the temperature rise ΔT ₂ of the steel slab S in the soaking zone is reduced and the furnace is operated with the latter-stage low-load heat pattern, the skid mark portion is compared with the case where the latter-stage high-load type heat pattern is used It has been found that the amount of decrease in the temperature of the steel sheet is reduced, the plate-passability in the hot rolling mill is stabilized, and as a result, the rolling efficiency is improved. Further, the temperature decrease amount of the skid mark portion with respect to the steady portion has a good correlation with the temperature increase amount of the steel slab S in the soaking zone.

In order to determine the temperature increase ΔT ₂ of the steel slab S in the soaking zone in correspondence with the operation mode of the hot rolling facility, it is preferable to use a table value (S 10). This is because it is easy to classify and store in the computer according to the size, material, component, etc. of the steel slab S, and to make subsequent changes easily.
As described above, when determining the furnace temperatures θ _1,1 , θ _1,2 , and θ ₂ of each zone, the combustion control method of the continuous heating furnace according to the present invention first operates the hot rolling facility operation mode. The temperature increase amount ΔT ₂ of the steel slab S in the soaking zone is determined in accordance with the above, and then the furnace temperature θ ₂ in the soaking zone is set to the temperature rising amount ΔT ₂ of the steel slab S in the soaking zone and the steel slab Determined from the in-furnace time of S

That is, when the furnace is operated in accordance with the operation mode of the hot rolling facility that prioritizes the fuel intensity as in the conventional combustion control method of the continuous heating furnace, the steel slab S in the soaking zone is used. The temperature increase amount ΔT ₂ is increased to obtain a post-stage high load type heat pattern. On the other hand, when the furnace is operated in accordance with the operation mode of the hot rolling facility with priority on the rolling efficiency, the temperature increase ΔT ₂ of the steel slab S in the soaking zone is reduced, and the latter low load type Use a heat pattern.

FIG. 3 shows a combustion control flowchart of the continuous heating furnace according to the present invention described above. On the other hand, the combustion control flowchart of the continuous heating furnace which heats the steel piece before applying this invention was shown in FIG.
In the combustion control of the continuous heating furnace for heating the steel slab before applying the present invention, first, the temperature rise ΔT ₂ of the steel slab in the soaking zone is determined so that the heat load in the soaking zone is maximized. Later, since the furnace temperature in the soaking zone was determined, the material to be rolled could not be heated with a heat pattern corresponding to the rolling operation mode, and the combustion control usage rate of the continuous heating furnace using a computer was 15%. It was low.

  On the other hand, according to the combustion control of the continuous heating furnace according to the present invention, since the temperature rise amount of the material to be rolled in the soaking zone is determined according to the operation mode of the hot rolling equipment, a computer is used. The combustion control usage rate of the continuous heating furnace has been improved to 35%.

It is a schematic diagram which shows the structure of the continuous heating furnace which heats the steel piece to which this invention is applied. It is a characteristic view which illustrated the influence factor which makes it suitable for the combustion control of the continuous heating furnace concerning this invention, and can roll a suitable steel piece stably. It is a combustion control flowchart of a continuous heating furnace which heats the steel piece concerning this invention. It is a combustion control flowchart of the continuous heating furnace which heats the steel piece before applying this invention. It is a schematic diagram which shows the structure of the conventional continuous heating furnace.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Furnace 2 Walking beam 3 Transfer device 3A Loading door 3B Extraction door 4 Temperature calculation device 5 Space calculation device 6 Movement amount detector 7 Tracking device 9 Furnace temperature 11 of the transfer position control device zone Extraction detector 12 Extraction Detector 13 Thermometer θ _1,1 Furnace temperature θ of the first heating zone _1, 2 Furnace temperature of the second heating zone θ ₂

Claims (3)

In the combustion control method of a continuous heating furnace in which the material to be rolled in the furnace is sequentially conveyed from the charging side to the extraction side, heated by the heating temperature in the heating zone, and then heated by the temperature increase in the soaking zone.
First, the temperature increase amount of the material to be rolled in the soaking zone is determined in accordance with the operation mode of the hot rolling facility, and then the furnace temperature in the soaking zone is set to the determined temperature rise of the material to be rolled in the soaking zone. A combustion control method for a continuous heating furnace, characterized in that it is determined from the amount of heat and the in-furnace time of the material to be rolled.   The temperature rise amount of the material to be rolled in the soaking zone is determined in consideration of a relationship with an influence factor that enables the material to be rolled to be stably rolled, which is obtained by analyzing in advance. The combustion control method of the continuous heating furnace as described in 1. The influential factor that enables stable rolling of the material to be rolled is defined as a temperature drop amount of the skid mark portion with respect to the steady portion when the temperature of the material to be rolled reaches the extraction target temperature. Item 3. A combustion control method for a continuous heating furnace according to Item 2.

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