JPS6036452B2 - Control method for continuous heating furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of controlling a lotus style heating furnace used for heating slabs and the like.

Generally, in heating control of a continuous heating furnace, it is necessary to uniformly heat the slab to a temperature suitable for rolling and at the same time to bake the slab according to the pitch required by the rolling line after the heating furnace.

Conventionally, this type of control has been carried out by controlling the temperature of the atmosphere inside the furnace, but it is extremely difficult to control a large number of slabs with different loads (plate thickness, etc.), and the temperature setting value for each control zone is extremely difficult. is determined uniformly, ignoring the load.

The present invention has been made with the aim of solving the above-mentioned problems, and is a heating control method that can accurately heat a large number of slabs with different loads to a target extraction temperature in a time required by a rolling line. The purpose is to provide the following. The temperature distribution in the continuous heating furnace is expressed as a function of the immersed fuel flow rate in each control zone and the temperature of each slab as shown in the following equation.

Tgi=fi(△t,G,,G2,...GmTg,o
, Tg20,.・・Tgn〇, TS,, TS2, . ．．
．． TSm) ...[11 However, (i=1-n
) TB: Gas temperature at T: Gas temperature before time Δt Ts: Slab temperature G: Fuel flow rate n: Number of control zones m: Number of slabs in the furnace Also, the temperature of each slab is the gas temperature determined by formula 01 T
It is expressed as a function of gi as shown in the following equation.

TSj=gi(△t, Tg,, Tg2,..., T6n,
TSjo) ... [21 However,
(j=1...m)Ts.

: Slab temperature before time Δt The present invention is based on the above {11 formula and '2
Using one formula repeatedly, each slab temperature Ts after an arbitrary time is determined.
j* is predicted, and the fuel flow rate in each control zone is determined so as to minimize the sum of deviations from the target temperature rise curve of each slab shown in FIG.

Hereinafter, a control method in an embodiment of the present invention will be explained with reference to the drawings.

In FIG. 2, 1 is a heating furnace, 2 is a combustion burner, 3 is a fuel flow meter, 4 is a fuel control valve, and 5 is a calculation device.

The flow rate setting is made in the arithmetic unit 5 at certain time intervals Δt.

First, based on the average value of the actual flow rate indicated by the flowmeter 3 during the above time interval Δt and the gas temperature and slab temperature at the previous calculation, the gas temperature distribution and slab temperature distribution up to this time are calculated as follows. Time interval △tl (△tl=△t/N
NZI) Equation '1} and Equation (2) are used alternately and repeatedly in increments to determine the gas temperature distribution and each slab temperature at the current time. Next, assuming the input fuel flow rate with the gas temperature distribution and each slab temperature calculated at the current time as initial values, the gas temperature distribution and each slab temperature Tsj after △t2 in the future (△t2=N2△[N221) is predicted and calculated using the method described above.

Next, the slab position x △t* after △t2 is predicted from the slab position Xo at the current time and the slab transport information, and △t
2, each slab target temperature Tsj* is determined. The deviation index Jn is determined from the predicted temperature Tsj and the target temperature Tsj* as follows.

Jn=JinQj(TSi*-TSj)2 --Gluej:
1 However, Qj: Weighting coefficient for each slab The calculation device 5 sets the flow rate of each control band so as to minimize the value of Jn.

A known optimization method (
For example, the steepest descent method may be used. When the calculation unit 5 completes the above calculation, the calculation unit 5 instructs the set value to the fuel control valve 4 to adjust the fuel flow rate of the burner 2. As described above, according to the present invention, it is possible to provide a method for controlling a continuous heating furnace that can accurately control the extraction temperature for a large number of slabs with different loads.

[Brief explanation of drawings]

FIG. 1 is a curve diagram showing target temperature increase characteristics of a slab, and FIG. 2 is a schematic diagram showing an apparatus to which a continuous heating furnace control method according to an embodiment of the present invention is applied. In the figure, 1 is a heating furnace, 2 is a burner, 3 is a flow meter, 4 is a control valve, and 5 is a computing unit. Figure 1 Figure 2

Claims (1)

[Claims] 1 Assuming the fuel flow rate in each control zone of the continuous heating furnace, predict the temperature of each slab in the furnace after an arbitrary time, find the deviation between this predicted temperature and the target temperature rise curve of each slab, and calculate the A method for controlling a continuous heating furnace, characterized in that the fuel flow rate in each of the control zones is determined so that the sum of the squares of the deviations multiplied by coefficients is minimized.