KR960006030B1 - Temperature fixing method of heating furnace atmosphere - Google Patents

Temperature fixing method of heating furnace atmosphere Download PDF

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KR960006030B1
KR960006030B1 KR1019930023749A KR930023749A KR960006030B1 KR 960006030 B1 KR960006030 B1 KR 960006030B1 KR 1019930023749 A KR1019930023749 A KR 1019930023749A KR 930023749 A KR930023749 A KR 930023749A KR 960006030 B1 KR960006030 B1 KR 960006030B1
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South Korea
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temperature
steel
furnace
atmosphere
extraction
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KR1019930023749A
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Korean (ko)
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KR950014336A (en
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홍성철
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포항종합제철주식회사
조말수
재단법인산업과학기술연구소
백덕현
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D11/00—Process control or regulation for heat treatments
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0003—Monitoring the temperature or a characteristic of the charge and using it as a controlling value

Abstract

This method provides (a) precise prediction of discharge temperature of steel and the degree of heating uniformity, by improvement of setting method of atmosphere temperature and calculating method of temperature of steel in the heating furnace for hot rolling, and (b) control of a rapid period by reduction of calculation time. When the number of zones in the heating furnace is n, the atmosphere temperature of each zone from the inlet of furnace to zone K is calculated by Tm. Here, Tm is the estimated discharge temperature by Rounge-Kutta method. And the atmosphere temperature of each zone from inlet to zone n-K is calculated by Tm and Sm. Here, the estimated discharge temperature, Tm is the average temperature of each mesh, and the estimated degree of heating uniformity, Sm, is the difference between the maximum and the minimum mesh temperature.

Description

강재온도제어를 위한 가열로내 분위기 온도설정방법Ambient temperature setting method in furnace for steel temperature control

제1도는 통상의 가열로를 나타내는 개략도.1 is a schematic view showing a conventional heating furnace.

제2도는 종래의 방법에 따라 강재온도제어를 한 경우 가열시간에 따른 가열로분위기온도, 강재온도 및 균열도 변화를 나타내는 그래프.2 is a graph showing changes in furnace atmosphere temperature, steel temperature and cracking degree according to heating time when steel temperature control is performed according to a conventional method.

제3도는 본 발명에 따른 강재온도 제어를 한 경우 가열시간에 따른 가열로 분위기온도, 강재온도 및 균열도 변화를 나타내는 그래프.3 is a graph showing changes in the furnace atmosphere temperature, the steel temperature and the cracking degree according to the heating time when the steel temperature control according to the present invention.

본 발명은 열간압연 공정에 있어서 강재온도제어를 위해 가열로내 분위기 온도를 설정하는 방법에 관한 것이다.The present invention relates to a method for setting an ambient temperature in a furnace for controlling steel temperature in a hot rolling process.

열간압연 공정에서는 강재를 압연하는데 용이하게 하기 위해 압연기의 용량, 제품품질 문제를 고려하여 압연하기전 강재를 적절한 온도로 가열해주는 역할을 하는 가열로가 있다. 대부분의 가열로는 예열대, 가열대, 균열대로 구분되어 있어 각대의 분위기 온도를 설정하여 강재를 가열한다. 강재온도 제어는 가열로내 상황, 즉 가열로 분위기 온도, 강재의 위치, 그리로 강재의 추출시간등을 고려하여 컴퓨터에서 주기적으로 현재의 강재온도, 추출시 예상강재온도등을 계산한후 이 계산된 값들을 고려하여 가열로 분위기 온도를 설정하여 가열로에 보내는 형식으로 이루어진다.In the hot rolling process, there is a heating furnace that serves to heat the steel to an appropriate temperature before rolling in consideration of the capacity and product quality problems of the rolling mill to facilitate the rolling of the steel. Most heating furnaces are divided into preheating zone, heating zone, and cracking zone to set the temperature of each zone to heat steel materials. The steel temperature control calculates the current steel temperature and the expected steel temperature during extraction periodically by computer, taking into account the conditions in the furnace, that is, the furnace atmosphere temperature, the steel position, and the extraction time of the steel. It takes the form of taking into account the set values and setting the furnace atmosphere temperature and sending it to the furnace.

종래의 강재 온도제어방법으로는 다음과 같은 것들이 있다.Conventional steel temperature control methods include the following.

(a) 각대에 있는 강재의 추출목표온도와 목표 균열도(고르게 가열된 정도), 각대의 분위기 온도와 대간 온도차의 조업상 실현가능 범위, 그리고 에너지 최소화를 고려하여 각 대의 분위기 온도를 설정하기 위해 선형계획법을 이용하는 강재온도 제어방법이 있는데, 강재의 추출온도와 균열도를 차분법에 의해 열전도방정식을 풀어 구하는 경우와 희귀분석을 통해 만들어진 식에 의해 구하는 경우가 있다. 차분법을 이용하면 분위기 온도 설정을 위한 계산량이 많아 계산설정하는데 많은 시간이 필요하며 빠른 주기의 제어와 보다 많은 강재에 대한 제어에 어려움이 있고, 회귀분석식을 이용하면 강재의 추출온도와 균열도가 부정확하게 예측되는 문제점이 있다.(a) To set the atmospheric temperature of each unit in consideration of the extraction target temperature and the target cracking degree (evenly heated) of the steel in each zone, the operational feasibility range of each ambient temperature and the inter-temperature difference, and the minimization of energy; There is a steel temperature control method using the linear programming method. The extraction temperature and the cracking degree of the steel are obtained by solving the thermal conductivity equation by the difference method and by the equations generated through the rare analysis. The differential method requires a lot of calculation time for setting the atmosphere temperature, so it takes a lot of time to set up the calculation, and it is difficult to control the fast cycle and control more steels. There is a problem that is incorrectly predicted.

그리고 (b) 강재가 가열로에 장입해서 추출될 때까지 가열로 분위기 온도를 일정한 형태를 따르도록 하는 강재온도 제어방식이 있는데 이 방식은 가열로와 강재의 특성과 강재가 가열로에 머무르는 시간등이 고려된 가열로 분위기 온도 형태가 있어야 하는 단점이 있다.And (b) there is a steel temperature control method in which the atmosphere temperature of the furnace follows a certain shape until the steel is charged into the furnace and extracted, which is characterized by the characteristics of the furnace and the steel and the time the steel stays in the furnace. This contemplated heating has the disadvantage of having an ambient temperature form.

이와같은 종래의 강재온도 제어는 보다 정확한 강재 온도제어를 위해, 빠르게 강재온도를 예측할 수 있는 계산기능이 좋은 계산기가 필요하며 계산기 구입 비용이 많이 드는 문제가 있고 계산시간 단축을 위해 부정확한 강재 온도제어가 되는 문제점이 있다.Such conventional steel temperature control requires a calculator with good calculation function that can predict the steel temperature quickly for more accurate steel temperature control, has a problem of expensive calculator purchase, and inaccurate steel temperature control to shorten the calculation time. There is a problem.

본 발명자는 상기한 종래 방법들의 제반문제점을 해소하기 위하여 연구와 실험을 행하고, 그 결과에 근거하여 본 발명을 제안하게 된 것으로써, 본 발명은 분위기 온도 설정 방법과 강재 온도 계산방법을 개선함으로써, 개산시간을 단축하여 빠른 주기의 제어와 보다 정확한 강재추출온도 및 균열도 예측에 의해 강재의 추출 목표 온도와 균열도를 얻을 수 있는 가열로내 분위기 온도 설정방법을 제공하고자 하는데 그 목적이 있다.MEANS TO SOLVE THE PROBLEM The present inventor conducted research and experiment in order to solve the said trouble of the said conventional methods, and based on the result, this invention proposes this invention, The present invention improves the atmospheric temperature setting method and the steel material temperature calculation method, The purpose of the present invention is to provide a method for setting the atmosphere temperature in a furnace to obtain the extraction temperature and the cracking degree of steel by controlling the period of time and predicting the steel extraction temperature and the crack degree more precisely.

이하, 본 발명에 대하여 상세히 설명한다.EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

본 발명은 열간압연 공정에서 강재온도를 제어하기 위하여 n개의 대(Zone)로 이루어진 가열로내 분위기 온도를 설정하는 방법에 있어서, 가열로 입구로부터 K개의 강재의 예상추출온도만을 고려하여 각대의 분위기 온도를 설정하고, n-K개의 대는 강재의 예상추출온도와 예상 균열도를 고려하여 각대의 분위기 온도를 설정하는 강재 온도제어를 위한 가열로 내 분위기 온도 설정방법에 관한 것이다.The present invention is a method of setting the atmosphere temperature in the furnace consisting of n zones in order to control the steel temperature in the hot rolling process, each atmosphere considering only the expected extraction temperature of the K steel from the inlet of the furnace The temperature is set, and nK units are related to a method of setting an ambient temperature in a furnace for controlling steel temperature, which sets an ambient temperature in consideration of an expected extraction temperature and an expected cracking degree of steel.

이하, 본 발명에 대하여 보다 상세히 설명한다.Hereinafter, the present invention will be described in more detail.

본 발명에 따라 가열로내 분위기 온도를 설정하기 위해서는, 제1도에 나타난 바와같이, n개의 대(Zone)로 이루어진 가열로중 가열로의 능력을 고려하여 강재의 예상추출온도만을 고려할 때 즉, K개의 대와 강재의 예상추출온도와 예상추출온도와 예상 균열온도를 고려할 때 즉, n-K개의 대를 선정하여야 한다.In order to set the atmosphere temperature in the furnace according to the present invention, as shown in FIG. 1, when considering only the expected extraction temperature of the steel in consideration of the capacity of the furnace in the furnace consisting of n zones, that is, Considering the expected extraction temperature, the expected extraction temperature, and the expected cracking temperature of K bands and steel, that is, nK bands should be selected.

이때, 로온을 설정하므로서, 충분히 추출목표 균열도를 얻을 수 있는 최단 재로시간(강재가 가열로내에 머무는 시간)을 갖는 가열로내의 위치에 있는 대(Zone)를 K+1 대로 선정하는 것이 바람직하다.At this time, it is preferable to select the zone at the position in the furnace having the shortest ashing time (the time that the steel stays in the furnace) that the extraction target cracking degree can be sufficiently obtained by setting the furnace temperature as K + 1. .

다음에, 가열로 입구로부터 K개의 대에 있는 강재의 예상추출온도 (Tm)와 n-K개의 대에 있는 강재의 예상추출온도(Tm) 및 예상균열도(Sm)을 구한다.Next, the expected extraction temperature (Tm) of the steels in the K bands, the expected extraction temperature (Tm) and the expected crack degree (Sm) of the steels in the n-K bands are obtained from the furnace inlet.

상기한 K개의 대에 있는 강재의 예상추출온도(Tm)는 하기 식(1)의 열전달방정식을 Rounge-Kutta법에 의해 풀어 구한다.The expected extraction temperature (Tm) of the steel in the K bands described above is obtained by solving the heat transfer equation of Equation (1) by the Rounge-Kutta method.

(여기서, T는 강재의 온도, t는 시간,cg는 총괄 열흡수율, ρ는 강재의 밀도, Cp는 강재의 비열, A는 강재의 표면적, V는 강재의 체적임)Where T is the temperature of the steel, t is the time, cg is the overall heat absorption rate, ρ is the density of the steel, Cp is the specific heat of the steel, A is the surface area of the steel, V is the volume of the steel)

상기한 n-K개의 대에 있는 강재의 예상추출온도(Tm) 및 예상균열도(Sm)는 다음과 같이 구한다. 즉, 하기 식(2)의 열전도방정식을 차분식화한 하기 식(3)에 의해 메쉬(mesh)들의 온도를 구한 다음, 이 메쉬들의 평균온도값을 강재의 예상추출온도(Tm)로, 그리고 메쉬의 최대 온도값과 최소온도값의 차를 강재의 예상 균열도(Sm)로 하여 구한다.The expected extraction temperature (Tm) and the expected cracking degree (Sm) of the steel in the n-K bands described above are obtained as follows. In other words, the temperature of the meshes is obtained by the following equation (3) which differentially formulates the thermal conductivity equation of the following equation (2), and then the average temperature of these meshes is the estimated extraction temperature (Tm) of the steel, and the mesh The difference between the maximum temperature value and the minimum temperature value is calculated as the expected cracking degree (Sm) of steel.

(여기서 T는 강재온도, x,y는 강재의 폭과 두께방향의 길이를 나타냄)Where T is the steel temperature and x and y are the width and length of the steel.

(여기서, Ti는 강재의 i번 매쉬(Mesh)의 온도, △t는 시간증분, Ki는 i번 메쉬의 열전도도, △X, △Y는 메쉬의 폭과 두께방향길이, ρi, Cpi는 i번의 메쉬의 밀도와 비열, fi는 i번 메쉬의 경계조건이 고려된 함수임) 상기 식(3)에서 △t는 하기 식(4)와 같이 선정되는데, 그 이유는 차분법에 의해 가능한한 빠르게 강재 온도를 계산하기 위함이다.Where Ti is the temperature of mesh i of the steel, Δt is the time increment, Ki is the thermal conductivity of mesh i, ΔX and ΔY are the width and thickness of the mesh, ρi, Cpi is i The density and specific heat of the burned mesh, fi is a function considering the boundary condition of the mesh i.) In the formula (3), Δt is selected as shown in the following formula (4), because the difference method To calculate the steel temperature.

가열로 입구로부터 K개의 대의 경우에는 상기 식(1)에서 구한 강재의 예상추출온도값(Tm)을 하기 식(5)에 대입하여 각대의 분위기 온도를 설정한다.In the case of K units from the inlet of the furnace, the atmosphere extraction temperature is set by substituting the estimated extraction temperature value Tm of the steel obtained in the above formula (1) into the following formula (5).

n-K개의 대의 경우에는 상기 식(3)에 의해 구한 강재의 예상추출온도값(Tm) 및 강재의 예상균열도값(Sm)을 하기 식(6)에 대입하여 각대의 분위기 온도를 설정한다.In the case of n-K units, the ambient temperature is set by substituting the estimated extraction temperature value Tm of the steel obtained by the above equation (3) and the estimated cracking degree value Sm of the steel into the following equation (6).

(상기 식(5) 및 (6)에서, n, k는 가열로의 대를 표시하는 수(In the above formulas (5) and (6), n and k are numbers representing the band of the heating furnace.

Tg(n), Tgo(n)는 n대의 설정분위기 온도, 현재 분위기 온도Tg (n) and Tgo (n) are the n set atmosphere temperatures and the current atmosphere temperature.

Tm(n), Tt(n)는 n대에 있는 강재의 예상추출온도, 목표추출온도Tm (n) and Tt (n) are the expected extraction temperature and target extraction temperature of steel in n units.

Sm(n), St(n)는 n대에 있는 강재의 예상추출균열도, 목표추출 균열도Sm (n) and St (n) are the expected extraction crack and target extraction crack of steel in n

a(n), b(n)는 계수)a (n), b (n) are coefficients)

상기 식(5) 및 (6)에 있어서, 계수 a 및 b는 열손실이 적은 대순으로 큰 값을 주는 것이 바람직하다.In the above formulas (5) and (6), the coefficients a and b are preferably given large values in order of low heat loss.

상기와 같이, 가열로 입구로부터 K개의 대의 경우에는 강재의 예상추출온도만을 고려하고, n-k개의 대의 경우에는 강재의 예상추출온도 및 예상 균열도를 고려하여 노내분위기 온도를 설정하므로써, 계산시간을 단축시킬 수 있게 된다.As described above, the calculation time is shortened by setting only the expected extraction temperature of the steel in the case of K units from the inlet of the furnace, and setting the atmosphere temperature in the case of nk units in consideration of the expected extraction temperature and the expected cracking degree of the steel. You can do it.

이하, 실시예를 통하여 본 발명을 보다 구체적으로 설명한다.Hereinafter, the present invention will be described in more detail with reference to Examples.

[실시예]EXAMPLE

가열대와 균열대로 구성된 가열로에 스테인레스강이 장입되어 90초마다 일정한 간격으로 이송되면서 가열되어 추출된다고 하고(가열대 재로시간=3420초, 균열대 재로시간=1800초), 추출목표온도를 1030℃, 목표 균열도를 25℃로 할때, 본 발명방법과 종래의 방법(강재의 온도를 차분법에 의해 구하여 선형계획법에 의해 노온을 설정하는 경우)를 이용하여 강재 온도제어를 행하고, 강재의 추출온도와 강재의 균열도를 조사하고, 그 결과를 종래의 방법의 경우에는 제2도에, 본 발명의 경우에는 제3도에 나타내었다.A stainless steel is charged into a heating furnace composed of a heating zone and a cracking zone, and is heated and extracted while being transferred at regular intervals every 90 seconds (heating zone ashing time = 3420 seconds, cracking furnace ashing time = 1800 seconds), and the extraction target temperature is 1030 ℃, When the target crack is set at 25 ° C, the steel temperature is controlled using the present invention and the conventional method (when the temperature of the steel is determined by the differential method and the furnace is set by the linear programming method), and the extraction temperature of the steel is obtained. The degree of cracking of and steels was investigated and the results are shown in FIG. 2 in the case of the conventional method and in FIG. 3 in the case of the present invention.

이때, 가열로 분위기 온도를 설정하는데 걸리는 계산시간은 본 발명의 경우 35초, 종래방법의 경우 15분이었다.At this time, the calculation time for setting the atmosphere temperature of the heating furnace was 35 seconds in the present invention and 15 minutes in the conventional method.

제2도 및 제3도에 나타난 바와같이, 본 발명의 경우에는 강재온도제어시 추출목표온도와 목표균열도를 얻을 수 있음과 동시에 계산시간이 종래의 방법을 이용할때 보다 18배 이상 단축됨을 알 수 있다.As shown in FIG. 2 and FIG. 3, in the present invention, it is possible to obtain the extraction target temperature and target crack degree during steel temperature control, and at the same time, the calculation time is reduced by 18 times or more than when using the conventional method. Can be.

따라서, 본 발명은 강재온도제어시 강재의 추출목표온도와 목표균열도를 획득함과 동시에 계산시간의 단축으로 빠른주기의 제어가 가능하도록 해준다.Therefore, the present invention enables the fast cycle control by shortening the calculation time while acquiring the extraction target temperature and target crack degree of the steel during steel temperature control.

Claims (1)

열간압연 공정에서 강재온도를 제어하기 위하여 n개의 대(Zone)로 이루어진 가열로내 분위기 온도를 설정하는 방법에 있어서, 가열로 입구로부터 K개의 각대의 분위기 온도는, 하기 식(1)을 Rounge-Kutta법에 의해 풀어 구한 강재의 예상추출온도를 하기 식(5)에 대입하여 구한 온도값으로 설정하고;In the method of setting the atmosphere temperature in the furnace consisting of n zones in order to control the steel temperature in the hot rolling process, the atmosphere temperature of each of the K zones from the inlet of the furnace is represented by the following formula (1). The expected extraction temperature of the steel obtained by the Kutta method is set to a temperature value obtained by substituting the following equation (5); 상기 n-K개의 각대의 분위기 온도는, 하기 식(2)를 차분식화한 하기 식(3)에 의해 메쉬(mesh)들의 온도를 구한 다음, 이 메쉬들의 평균온도 값을 강재의 예상추출온도(Tm)로, 그리고 메쉬의 최대온도값과 최소 온도값의 차를 강재의 예상 균열도(Sm)로 하고 이 예상추출온도(Tm)와 예상균열도(Sm)를 하기 식(6)에 대입하여 구한 온도값으로 설정하고;The ambient temperature of each of the nK angles is obtained by calculating the temperature of the meshes by the following equation (3) by differential equation (2), and then calculating the average temperature of these meshes as the expected extraction temperature (Tm) of the steel. The temperature obtained by substituting the difference between the maximum temperature value and the minimum temperature value of the mesh as the expected cracking degree (Sm) of the steel and substituting the estimated extraction temperature (Tm) and the estimated cracking degree (Sm) in the following equation (6) Set to a value; 상기 식(3)에 있어 △t가, 하기 식(4)Δt in the formula (3) is represented by the following formula (4) 와 같이 선정되고; 그리고, 상기 식 (5) 및 (6)에 있어 계수 a와 b가 열손실이 적은 대 순으로 큰값이 설정되는 것을 특징으로 하는 강재온도 제어를 위한 가열로내 분위기 온도설정방법.Is selected as; And, in Equations (5) and (6), the coefficients a and b are set in the order of the smallest heat loss, and the larger values are set.
KR1019930023749A 1993-11-09 1993-11-09 Temperature fixing method of heating furnace atmosphere KR960006030B1 (en)

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