JPS63140036A - Method for identifying overall heat absorptivity of continuous heating furnace - Google Patents

Abstract

PURPOSE:To efficiently identify overall heat absorptivity and to improve working efficiency by measuring the surface temps. of ingots and furnace temps. in the respective zones of a heating furnace and providing means for computing the overall heat absorptivity from the measured values and the data stored in a memory. CONSTITUTION:Furnace temp. sensors 11 and radiation thermometers 12 for measuring the surface temps. of the ingots (materials to be heated) residing in the continuous heating furnace 10 are provided to the plural heating zones of said furnace. The data on the sizes, material quality, etc., of the ingots are inputted via an input device 13 to the memory 14 and the measured values of the sensors 11 are inputted to the memory 14. The in-furnace positions of the ingots residing in the furnace are computed by a position computer 15 and the temps. of the ingots are estimated by a temp. computer 17 from the data stored in the memory, the measured furnace temp. values and the computed temp. values of the ingots stored in the memory. The overall heat absorptivity of the continuous heating furnace is identified by an overall heat absorptivity computer 16 by using the computed material temps. and the measured surface temps. of the ingots. This method is applicable to each one of the materials to be heated.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to a continuous billet heating furnace that heats a material to be heated such as a slab or billet (hereinafter simply referred to as "r billet"). , when the steel billet is heated in the heating furnace and moves from the insertion port to the extraction port,
An overall heat absorption rate identification device for continuous heating furnaces that can calculate and identify the overall heat absorption rate from the surface temperature of the steel billet measured by radiation thermometers installed in each zone such as the heating zone and soaking zone. Regarding.

(Prior art) In a continuous heating furnace that has multiple zones such as a residual zone, a heating zone, and a soaking zone, each zone has different characteristics such as the furnace structure, furnace temperature setting, fuel combustion efficiency, and the presence of steel billets. Since the furnace time and other factors differ, the amount by which the steel billet is heated during the period when the billet is in the furnace in each zone differs greatly.

The steel slab is heated by the amount of radiant heat q transferred from the combustion gas.

The amount of radiant heat transfer q is calculated from Stefan-Boltzmann's law (θ +273) l (1) where γ is the Stefan-Boltzmann constant (Kcal/m3
hr'K), Φ. . is the overall heat absorption rate of the continuous heating furnace, θ +273 is the absolute temperature of the furnace temperature (χ), and θ +273 is the absolute temperature of the surface of the steel piece (°K).

When extracting steel slabs, in order to bake the steel slabs to the extraction target temperature, the temperature of the steel slabs must be raised accurately in each zone by appropriate radiation heat transfer ff1q during the period in which the steel slabs are in the furnace. There is a need.

The amount of radiation heat transfer q is the overall heat absorption rate Φ of the continuous heating furnace, as shown in equation (1) above. . This includes the overall heat absorption rate Φ of this continuous heating furnace. . is a constant that indicates the rate of heat transfer from combustion gas to the surface of the steel piece, and varies depending on the size and structure of the furnace. In order to accurately bake the steel billet to the extraction target temperature when extracting the steel billet, the required radiation heat transfer ff1
It is necessary to accurately calculate the furnace temperature θ from Q using equation (1) and control the heating furnace using the furnace temperature determined.

In this case, the overall heat absorption rate of the continuous heating furnace. . If the accuracy of is insufficient, it is not possible to accurately calculate the furnace temperature θ.

Conventionally, a sample of a single steel billet was taken, and thermocouples were used to accurately measure the surface temperature, internal temperature, and combustion gas temperature near the surface of the billet, and the continuous heating furnace was based on the measured temperature history. The overall heat absorption rate Φ. 6 was calculated, and the overall heat absorption rate Φ of the continuous heating furnace was derived using that sample for the actual heated steel billet. . was applied.

Figure 2 is an explanatory diagram showing the temperature measurement points in the conventional means of measuring the temperature of a steel billet using a thermal lightning pair. Thermocouples were embedded and further thermocouples were installed near the surface to precisely measure the temperature history of the steel piece from the time it was inserted into the heating furnace until it was extracted.

Overall heat absorption rate Φ of continuous heating furnace using measured temperature history. . One method for finding the value of is briefly shown below.

First, the surface and internal temperatures of the steel billet are estimated by assuming several values of the overall heat absorption rate ΦcG of the continuous heating furnace.

This is divided into three parts based on the well-known one-dimensional heat conduction difference equation.

Heat content after a fixed time interval Δ from time t inside the piece of steel〉 Heat content on the upper surface of the piece of steel〉 (Heat content on the lower surface of the piece of steel〉 (i - n)・・・・・・
...(4) Here, H4 is the heat content at the first point from the top surface of the steel slab (Kcal/kg), φ1 is the conversion temperature at the i-th point from the top surface of the steel slab, K is the steel slab Thermal conductivity (Kcal/mhr'c), ρ
is the density of the steel slab (kg/m''), Δt is the fixed time interval (hr), and ΔX is the dividing pressure #i (m) in the thickness direction of the steel slab.

The temperature of the steel billet can be easily estimated by calculating the heat content at regular time intervals (Δt) and converting the obtained heat content into temperature.

The overall heat absorption rate Φ of the continuous heating furnace in which the history of the estimated temperature value of the steel slab obtained and the history of the measured temperature value of the steel slab measured using the heat conduction described above are in good agreement. . Select a value. If a value of the overall heat absorption rate ΦCG of the continuous heating furnace that matches well cannot be found, the overall heat absorption rate Φ of the continuous heating furnace. . Change the value of to a new value and estimate the temperature of the billet again. By repeating these procedures, the overall heat absorption rate of the continuous heating furnace Φ
. We are finding the value of 6.

(Problems to be Solved by the Invention) In the conventional continuous heating furnace overall heat absorption coefficient ΦCG identification method, heat conduction is measured on the surface, inside, and near the surface of the steel billet, as shown in Figure 2. It must be installed accurately in the position and requires skilled technique.

Furthermore, since the sample steel billet with the thermal lightning pair installed cannot be rolled into a product by a rolling mill, it is necessary to remove it from the rolling line once the heating furnace is extracted.

Moreover, the overall heat absorption rate Φ of the continuous heating furnace obtained in this way. Since a value of 0 is accompanied by an error, it is necessary to measure the temperature history using samples with similar thermocouples installed on several pieces of steel, making temperature measurement tasks such as installing thermocouples difficult. be.

Here, the present invention relates to the overall heat absorption rate Φ. . When the furnace is in normal operation, it is possible to identify the , by using the surface temperature of the steel billet measured by a radiation thermometer in each zone of the heating furnace and the furnace temperature measured by a furnace thermometer in each zone of the heating furnace, the total heat absorption of a continuous heating furnace can be efficiently calculated. Rate Φ. .

The purpose is to provide an overall heat absorption rate identification device for continuous heating furnaces that identifies the value of .

[Structure of the invention]

(Means for Solving the Problems) The present invention has a plurality of zones corresponding to the heating process of the material to be heated, and each zone has a furnace temperature sensor for measuring the furnace temperature and a surface of the material to be heated. A continuous billet heating furnace equipped with a radiation thermometer to measure temperature has a data input device for inputting data such as the dimensions and material of the material to be heated, and the data entered by the data input device and the material to be heated are A memory is provided to store the temperature calculation value of the temperature and the furnace temperature measurement value measured by the furnace temperature sensor, and the position of the material to be heated in the heating furnace can be determined based on the extracted signal from the heating furnace. It is equipped with a position calculator that calculates the dimensions and material of the material to be heated stored in the memory, the furnace temperature measurements previously measured by the furnace temperature sensor and stored in this memory, and the past calculations. It has a temperature calculator that estimates the temperature of the heated material from the temperature calculation value of the heated material stored in this memory, and the material temperature of the heated material calculated by the temperature calculator and the radiation temperature. An overall heat absorption rate identification device for a continuous heating furnace, which is equipped with a continuous heating furnace overall heat absorption rate calculator that calculates the overall heat absorption rate of the continuous heating furnace from the surface temperature measurement value of the IJLI thermal material measured by the IJLI thermal material. It is.

(Function) The present invention is based on Stefan Boltzmann's law and the interior of the heated material after a certain time interval in each zone in which the heated material is heated in a continuous heating furnace.

Applying the one-dimensional heat conduction difference equation for the upper and lower surfaces, from the measured values of the furnace temperature and the radiant temperature of the heated material, the radiant temperature of the heated material after a certain period of time estimated at the previous temperature measurement is calculated as follows:
If the difference between the measured value of the radiation temperature of the material to be heated after a certain period of time is larger than the allowable error, the overall absorption rate of the continuous heating furnace estimated by converting the difference between the two into a coefficient is corrected, and the actual value is adjusted. It is a means of matching.

(Embodiment) FIG. 1 is a block diagram showing a circuit configuration in an embodiment of the present invention.

This embodiment has a plurality of zones corresponding to the heating process of the material to be heated (for example, a steel billet), and each zone has a furnace temperature sensor 11 for measuring the furnace temperature, and a furnace temperature sensor 11 for measuring the furnace temperature in each zone. In a continuous heating furnace 10 equipped with a radiation thermometer 12 that measures the surface temperature of a steel billet, data about the steel billet (dimensions,
It has a data input device 13 for inputting information such as material, etc.

In addition, a memory 14 is provided to store and hold the data inputted through the data input device 13, the billet temperature calculated by the billet temperature calculator 17 described later, and the furnace temperature measurement value measured by the furnace temperature sensor 11. establish.

From the dimensions of the steel billet stored in the memory 14, the position of the steel billet in the furnace is calculated every time the steel billet moves toward the extraction port due to extraction in the heating furnace, and the steel billet is placed at the next radiation thermometer measurement position. The heated material (one piece) position calculation means 15 is provided to determine that the heated material (one piece) has reached the position.

The dimensions and material of the steel slab stored in the memory 14, the furnace temperature measured by the furnace temperature sensor 11 and stored in the memory 14, and the values calculated in the past and stored in the memory 14. A temperature calculator 17 is provided which estimates the temperature of the steel piece at the time when the surface temperature of the steel piece is measured by the radiation thermometer from the estimated temperature value of the steel piece using equations (1) to (4).

Furthermore, the estimated value of the surface temperature of the steel piece estimated by the temperature calculator 17 and the measured value of the surface temperature of the steel piece measured by the radiation thermometer 12 are compared, and if the difference is larger than the tolerance ε, the value of the surface temperature of the steel piece is compared. The overall absorption rate Φ of the continuous heating furnace is determined by multiplying the difference by a certain constant. Correct the value of 0 to obtain the correct overall absorption rate Φ of the continuous heating furnace. . It is equipped with a continuous heating furnace overall absorption rate ΦcG calculator 16 that calculates the value of ΦcG.

Next, the procedure for identifying the overall heat absorption rate in the continuous heating furnace according to the present invention will be described.

FIG. 3 is an explanatory diagram showing a state in which the steel billet S existing in the first zone of the heating furnace moves from the direction of the insertion port toward the extraction port and reaches the (i+1)th zone.

The steel piece S is at time t. Radiation thermometer 11 installed in the first zone at
・The furnace is located directly below Hl, and the surface temperature θ (1) of the steel slab S is measured by the radiation thermometer 12 ・Hl.
SO can be measured.

Each time the heating furnace extracts, the steel slab S moves toward the extraction port, and at time t after n times of movement, it reaches the position directly below the radiation thermometer H1+1 in the (i+1)th zone, and the radiation is measured. Ru. Third
G, G, +1 in the figure represent the furnace temperature sensors 11 installed in the first zone and the (i+1)th zone, and G, G11
1, it is possible to measure the furnace temperature of the zone where the steel slab S is in the furnace.

FIG. 4 shows time t. The steel piece S that changes between and time tn
It is a temperature change diagram of the surface temperature of.

In FIG. 4, Δt, (j-0 to n-1) is time t,
to time tj+1 (extraction pitch).

Time t. The temperature change during the period from time tn to time tn is given by the above (1
) to (4), the overall absorption rate Φ of an appropriate continuous heating furnace is determined using the furnace temperature measurement values measured by the furnace temperature sensors G1 and G111. . It can be estimated by assuming that

Here, if the overall absorption rate Φ of the continuous heating furnace. The value of 6 is the overall absorption rate Φ of the actual continuous heating furnace. . If the temperature change of the steel slab S is estimated using equations (1) to (4) described above, assuming that the temperature is larger than the value of The estimated surface temperature value θ (t )' of the steel piece S at is larger than the constant value 8 of the radiation thermometer β measured in the n (i+1)th zone (1).

n Also, the overall absorption rate Φ of the continuous heating furnace. . Assuming that the value of is the same as the actual value, the steel billet S
When estimating the temperature change, the estimated surface temperature of the steel slab S changes as shown by curve A, and the estimated surface temperature of the steel slab S at time t becomes (i-th).

Furthermore, the overall absorption rate Φ of the continuous heating furnace. . If we assume that the value of is smaller than the actual value and estimate the temperature change of the steel slab S using equations (1) to (4) above, the estimated surface temperature of the steel slab S will change as shown by curve A'. Then, the steel piece S at time t
By comparing the estimated surface temperature at time t calculated using equations (1) to (4) above, the estimated surface temperature of the steel slab S can be calculated using the estimated surface temperature of The overall absorption rate Φ of the continuous heating furnace included in the above equations (1) to (4). . It can be determined whether the value of is accurate.

If the estimated surface temperature of the steel piece S is curve A' or curve A
', and becomes larger than the steel ε at time t, the overall absorption rate Φ of the continuous heating furnace. . The value of CA ΦCG' −ΦCG ”l [θ8(tn)−08
(tn)]...(5) Here, Kl is corrected by a positive constant and is changed again from time 10 to time t. Estimate the change in surface temperature of the steel piece S.

Thus, the overall absorption rate Φ of the continuous heating furnace. 6 value (5
) by performing a convergence calculation, it is possible to approach an accurate value of ΦcG.

Then, the overall absorption rate Φ of the continuous heating furnace is determined when the surface temperature estimate θ (1) calculated using the above-mentioned equations (1) to (4) and the radiation thermometer become smaller than the Mjn error ε. It is determined that 6 has been identified.

In this way, an accurate value of the overall absorption rate of the continuous heating furnace can be easily derived.

〔Effect of the invention〕

Thus, according to the present invention, there is no need to use thermocouples to measure the surface temperature, internal temperature, combustion gas temperature near the surface, etc. of the material to be heated (for example, a steel piece), and the heating furnace can be operated normally. Using the surface temperature of the material to be heated measured by a radiation thermometer in each zone of the heating furnace and the furnace temperature measurement value measured by a furnace temperature sensor in each zone of the heating furnace, Overall absorption rate Φ of heating furnace. .

can be identified, work efficiency is significantly improved, and it can be applied to each heated material, greatly improving quality and reducing costs.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the circuit configuration of an embodiment of the present invention, Fig. 2 is an explanatory diagram of the temperature measurement point using a conventional thermocouple, and Fig. 3 shows that the material to be heated (steel billet) is in the heating furnace. FIG. 4 is a diagram showing temperature change characteristics with respect to time when the heated material moves inside the heating furnace. 10... Continuous billet heating furnace, 11... Furnace temperature sensor,
12... Radiation thermometer, 13... Data input device, 14
...Memory, 15...Position calculator, 16...Overall absorption rate Φ of continuous heating furnace. 6 computing unit, 17...temperature computing unit. Applicant's agent Mr. Sato - Figure 2 Crane Figure 3

Claims (1)

[Claims] 1. Having a plurality of bands corresponding to the heating process of the material to be heated,
Data for inputting data such as the dimensions and material of the material to be heated in a continuous heating furnace that is equipped with a furnace temperature sensor to measure the furnace temperature and a radiation thermometer to measure the surface temperature of the material to be heated in each of these zones. An input device, a memory that stores and stores the data input by the data input device, the temperature calculation value of the material to be heated, and the furnace temperature measurement value measured by the furnace temperature sensor, and a signal extracted from the heating furnace. A position calculator that calculates the position of the material to be heated in the heating furnace, the dimensions and material of the material to be heated that are stored in memory, and the information that has been measured by the furnace temperature sensor in the past and stored in this memory. A temperature calculator that estimates the temperature of the material to be heated from the stored furnace temperature measurement value and the temperature calculation value of the material to be heated that has been calculated in the past and is stored and stored in this memory; a continuous heating furnace overall absorption rate calculator that calculates the overall heat absorption rate of the continuous heating furnace from the material temperature of the heated material and the surface temperature measurement value of the heated material measured by a radiation thermometer; An overall heat absorption rate identification device for a continuous heating furnace, characterized by comprising: