JPH09256072A - Operation of continuous annealing furnace - Google Patents
Operation of continuous annealing furnaceInfo
- Publication number
- JPH09256072A JPH09256072A JP6426596A JP6426596A JPH09256072A JP H09256072 A JPH09256072 A JP H09256072A JP 6426596 A JP6426596 A JP 6426596A JP 6426596 A JP6426596 A JP 6426596A JP H09256072 A JPH09256072 A JP H09256072A
- Authority
- JP
- Japan
- Prior art keywords
- combustion
- furnace
- air
- temp
- temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、直火型連続焼鈍炉
の操業方法に関し、とくに焼鈍サイクルの変更時におけ
る焼鈍炉の操業方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating a direct-fired continuous annealing furnace, and more particularly to a method for operating an annealing furnace when changing an annealing cycle.
【0002】[0002]
【従来の技術】一般に、焼鈍炉では、焼鈍する材質によ
り焼鈍温度が決定され、焼鈍する材料が変われば、焼鈍
炉の炉温を変更しなければならない。従来、焼鈍炉にお
ける高温焼鈍サイクルから低温焼鈍サイクルへの変更に
際しては、燃焼用ガスを最少限まで減少させ、自然放冷
により炉温の低下を待つ方法が一般的に利用されてい
た。したがって、保温性能の高い焼鈍炉では、高温焼鈍
サイクルから低温焼鈍サイクルへの変更は、長時間を要
し、生産効率を低下させるという問題があった。2. Description of the Related Art Generally, in an annealing furnace, the annealing temperature is determined by the material to be annealed, and if the material to be annealed changes, the furnace temperature of the annealing furnace must be changed. Conventionally, when changing from a high temperature annealing cycle to a low temperature annealing cycle in an annealing furnace, a method of reducing the combustion gas to the minimum and waiting for the temperature of the furnace to decrease by natural cooling has been generally used. Therefore, in the annealing furnace having a high heat retention performance, there is a problem that the change from the high temperature annealing cycle to the low temperature annealing cycle requires a long time and the production efficiency is reduced.
【0003】また、加熱炉、焼鈍炉では、燃料ガスの供
給を停止し、燃焼用空気のみをバーナから炉内に噴出さ
せて、炉を完全に冷却する場合もある。しかし、加熱
炉、焼鈍炉では、排ガス煙道にレキュペレータを設置
し、このレキュペレータを通して排ガス顕熱で燃焼用空
気を予熱し、燃焼効率を高め、炉の熱効率を高めてい
る。そのため、燃焼空気は、炉冷却時も炉操業時と同様
にレキュペレータを通り熱交換されたのちバーナから炉
内へ流れる。したがって、燃焼用空気の温度は高くな
り、冷却効果が減少するという問題があった。Further, in the heating furnace and the annealing furnace, the supply of fuel gas may be stopped and only the combustion air may be jetted from the burner into the furnace to completely cool the furnace. However, in the heating furnace and the annealing furnace, a recuperator is installed in the exhaust gas flue, and the combustion air is preheated by the sensible heat of the exhaust gas through the recuperator to improve the combustion efficiency and the thermal efficiency of the furnace. Therefore, the combustion air flows into the furnace from the burner after being heat-exchanged through the recuperator during furnace cooling as well as during furnace operation. Therefore, there is a problem that the temperature of the combustion air becomes high and the cooling effect is reduced.
【0004】[0004]
【発明が解決しようとする課題】本発明は、上記した問
題点を解決し、直火型連続焼鈍炉における高温焼鈍サイ
クルから低温焼鈍サイクルへの変更を効率よく短時間に
完了できる連続焼鈍炉の操業方法を提供することを目的
とする。SUMMARY OF THE INVENTION The present invention solves the above problems and provides a continuous annealing furnace capable of efficiently and quickly completing the change from the high temperature annealing cycle to the low temperature annealing cycle in a direct-fired continuous annealing furnace. The purpose is to provide a method of operation.
【0005】[0005]
【課題を解決する手段】本発明者らは、直火型焼鈍炉に
おける効率的な炉の操業方法について鋭意検討した結
果、燃焼用空気の温度と流量を変更することで達成でき
る見通しを得て本発明を構成した。すなわち、本発明
は、直火型連続焼鈍炉において、高温焼鈍サイクルから
低温焼鈍サイクルへの変更に際し、燃焼継続が可能な最
低量の燃焼ガスを、低温の燃焼用空気とともに、燃焼バ
ーナに供給して、炉温を急速に低温焼鈍サイクルの設定
温度とすることを特徴とする連続焼鈍炉の操業方法であ
る。また、本発明は、前記燃焼用空気が 250℃以下の温
度の空気で、その供給量を空気比で 8.0以上とすること
を特徴とする連続焼鈍炉の操業方法である。Means for Solving the Problems As a result of earnest studies on an efficient furnace operating method in a direct-fired annealing furnace, the present inventors have obtained the prospect that it can be achieved by changing the temperature and flow rate of combustion air. The invention has been constructed. That is, the present invention, in the direct-fired continuous annealing furnace, when changing from the high temperature annealing cycle to the low temperature annealing cycle, the minimum amount of combustion gas that can continue combustion is supplied to the combustion burner together with the low temperature combustion air. The operating method of the continuous annealing furnace is characterized in that the furnace temperature is rapidly set to the set temperature of the low temperature annealing cycle. Further, the present invention is the method for operating a continuous annealing furnace, wherein the combustion air is air having a temperature of 250 ° C. or less, and the supply amount thereof is 8.0 or more in air ratio.
【0006】[0006]
【発明の実施の形態】本発明は、直火型加熱方式の連続
焼鈍炉に好適に適用できる。直火型加熱方式では、燃料
ガスと燃焼用空気をバーナに供給し、燃焼させ火炎から
の放射や、燃焼ガスによる対流によって伝熱を行うもの
である。本発明の方法を実施できる連続焼鈍炉の燃焼ガ
ス・空気の配管系統の概念図を図2に示す。BEST MODE FOR CARRYING OUT THE INVENTION The present invention can be suitably applied to a direct-fired heating type continuous annealing furnace. In the direct-fire heating system, fuel gas and combustion air are supplied to a burner and burned, and heat is transferred by radiation from a flame and convection by the combustion gas. FIG. 2 shows a conceptual diagram of a combustion gas / air piping system of a continuous annealing furnace capable of carrying out the method of the present invention.
【0007】鋼帯9は、連続焼鈍炉6で焼鈍されたの
ち、冷却帯7で冷却される。連続焼鈍炉6の排ガス10
は、排ガス用ファン1により煙道を通り炉外に排出され
る。煙道内には、ボイラ3、レキュペレータ2が設けら
れ、排ガスの顕熱が回収されている。炉が定常運転を行
っている時には、燃焼用空気14は、燃焼空気用ファン
5から送りだされ配管11を通ってレキュペレータ2に
入る。このとき、切換弁4は閉、切換弁4a、4bは開
とする。レキュペレータ2において、燃焼用空気14
は、排ガス10の顕熱と熱交換され高温空気となって、
配管11を通り流量制御弁15bで流量制御されバーナ
12に供給される。燃料ガス13は、別の配管を通り流
量制御弁15aで流量制限されてバーナ12に供給さ
れ、燃料空気と混合され燃焼する。The steel strip 9 is annealed in the continuous annealing furnace 6 and then cooled in the cooling zone 7. Exhaust gas 10 of continuous annealing furnace 6
Is discharged to the outside of the furnace through the flue by the exhaust gas fan 1. A boiler 3 and a recuperator 2 are provided inside the flue to collect the sensible heat of the exhaust gas. When the furnace is in steady operation, the combustion air 14 is sent from the combustion air fan 5 and enters the recuperator 2 through the pipe 11. At this time, the switching valve 4 is closed and the switching valves 4a and 4b are opened. In the recuperator 2, the combustion air 14
Is heat-exchanged with the sensible heat of the exhaust gas 10 to become high-temperature air,
The flow rate is controlled by the flow rate control valve 15b through the pipe 11 and is supplied to the burner 12. The flow rate of the fuel gas 13 is supplied to the burner 12 after the flow rate of the fuel gas 13 is limited by the flow rate control valve 15a, and the fuel gas 13 is mixed with fuel air and burned.
【0008】連続焼鈍炉6が高温焼鈍サイクルでの定常
運転から低温焼鈍サイクルへ変更する場合には、炉を高
温から低温に冷却する必要がある。炉温を変更する際に
は、まずバーナへの燃料供給量を流量制御弁15aで制
限し、燃焼を継続できる最低量とする。燃焼を継続しな
いと、再び燃焼を開始したときに炉温のハンチングが大
きくなりすぎ炉温の安定するまで長時間を要するため、
最低量の燃料供給で燃焼を継続することが望ましい。When the continuous annealing furnace 6 is changed from the steady operation in the high temperature annealing cycle to the low temperature annealing cycle, it is necessary to cool the furnace from the high temperature to the low temperature. When changing the furnace temperature, first, the fuel supply amount to the burner is limited by the flow rate control valve 15a to the minimum amount that allows combustion to continue. If combustion is not continued, hunting of the furnace temperature will become too large when combustion is restarted, and it will take a long time for the furnace temperature to stabilize.
It is desirable to continue combustion with a minimum amount of fuel supply.
【0009】また、炉温を変更する際には、切換弁4
a、4bを閉鎖し、切換弁4を開ける。燃焼空気用ファ
ン5から送り出された燃焼用空気は、レキュペレータ2
での熱交換を行わず、配管11を通りバーナ12に供給
される。レキュペレータ2での熱交換が行われないた
め、供給される空気は低温である。空気温度はできるだ
け低い方が望ましいが、250℃以下であれば好適であ
る。供給量は冷却開始当初は、流量制御弁15bを最大
に開放し、バーナに供給する。なお、その後の燃焼用空
気の供給量は、炉温と設定温度との差を検知しながら制
御することが望ましい。また、空気比として、8.0〜
20.0とすることが望ましく、8.0未満では、空気
量が少なすぎ、炉温の急速な低下が望めない。一方、2
0.0を超えると、供給空気の風圧により燃焼バーナが
失火するため、上限とした。When changing the furnace temperature, the switching valve 4
A and 4b are closed and the switching valve 4 is opened. The combustion air sent from the combustion air fan 5 is supplied to the recuperator 2
It is supplied to the burner 12 through the pipe 11 without performing heat exchange in. Since heat exchange is not performed in the recuperator 2, the supplied air has a low temperature. The air temperature is preferably as low as possible, but is preferably 250 ° C. or lower. At the beginning of cooling, the amount of supply is such that the flow control valve 15b is opened to the maximum and supplied to the burner. In addition, it is desirable to control the subsequent supply amount of the combustion air while detecting the difference between the furnace temperature and the set temperature. In addition, the air ratio is 8.0 to
It is desirable to set it to 20.0, and if it is less than 8.0, the amount of air is too small and a rapid decrease in the furnace temperature cannot be expected. Meanwhile, 2
If it exceeds 0.0, the combustion burner will misfire due to the wind pressure of the supply air, so the upper limit was made.
【0010】これにより、低温の空気が多量にバーナか
ら炉内に供給され、炉温の降下速度は増大する。高温の
空気を供給する場合に比べると、炉温の降下速度は著し
く大きい。低温の燃焼用空気の供給量は、バーナにより
異なるが、直火型バーナの場合600m3 /hr以上が
望ましい。本発明で、燃焼空気における低温とは、25
0℃以下が望ましい。燃焼空気の温度が250℃を超え
ると燃焼空気による冷却効果が小さい。As a result, a large amount of low-temperature air is supplied from the burner into the furnace, and the rate of decrease in furnace temperature increases. Compared with the case of supplying high-temperature air, the rate of decrease in furnace temperature is extremely high. The supply amount of low-temperature combustion air varies depending on the burner, but in the case of a direct-fired burner, it is preferably 600 m 3 / hr or more. In the present invention, the low temperature in the combustion air is 25
0 ° C or lower is desirable. When the temperature of the combustion air exceeds 250 ° C, the cooling effect of the combustion air is small.
【0011】連続焼鈍炉において、燃焼ガス量を燃焼が
継続できる最低値にし、さらに、バーナから供給する燃
焼用空気の温度と流量を変えて炉温を降下させた。炉内
各ゾーンにおける炉温の降下速度の測定結果を図1に示
す。図1から、燃焼用空気の温度を低く、かつ供給量を
増やすことにより、降下速度は大きくなる。In the continuous annealing furnace, the amount of combustion gas was set to the minimum value at which combustion could be continued, and the temperature of the combustion air supplied from the burner and the flow rate were changed to lower the furnace temperature. The measurement results of the rate of decrease of the furnace temperature in each zone in the furnace are shown in FIG. From FIG. 1, the lowering speed is increased by lowering the temperature of the combustion air and increasing the supply amount.
【0012】[0012]
【実施例】直火型燃焼バーナを備えた10ゾーンの加熱
帯を有する直火型連続焼鈍炉で、1110℃の高温焼鈍
サイクルから850℃の低温焼鈍サイクルへの変更を行
った。本発明例として、燃焼ガス量を、バーナのミニマ
ム燃焼状態である15m3 /hrとし、燃焼用空気を、
レキュペレータによる熱交換を行わず、バーナに供給し
た。そのときの燃焼用空気の温度は、210℃であっ
た。その際、燃焼用空気の供給量は、空気比9.3(6
00m3 /hr)とした。EXAMPLE A direct-fired continuous annealing furnace having a heating zone of 10 zones equipped with a direct-burning burner was changed from a high temperature annealing cycle of 1110 ° C. to a low temperature annealing cycle of 850 ° C. As an example of the present invention, the combustion gas amount is set to 15 m 3 / hr, which is the minimum combustion state of the burner, and the combustion air is
The heat was not exchanged by the recuperator and was supplied to the burner. The temperature of the combustion air at that time was 210 ° C. At that time, the supply amount of the combustion air is 9.3 (6
00 m 3 / hr).
【0013】従来例として、燃焼ガス量を、バーナのミ
ニマム燃焼状態である15m3 /hrとし、燃焼用空気
はレキュペレータによる熱交換を行い、その供給量は、
ミニマム燃焼状態に対応して空気比4.7(300m3
/hr)とした。燃焼用空気の温度は380℃であっ
た。これら本発明例および従来例の炉温の変化曲線を図
3に示す。As a conventional example, the amount of combustion gas is set to 15 m 3 / hr which is the minimum combustion state of the burner, the combustion air is heat-exchanged by a recuperator, and its supply amount is
An air ratio of 4.7 (300 m 3) corresponding to the minimum combustion condition
/ Hr). The temperature of the combustion air was 380 ° C. FIG. 3 shows the change curves of the furnace temperatures of the present invention example and the conventional example.
【0014】図3から、本発明例では、冷却開始から低
温焼鈍サイクルの設定温度に到達するまでの時間が約8
0minであり、従来例にくらべ約1/2に短縮された
ことがわかる。From FIG. 3, in the example of the present invention, the time from the start of cooling to the set temperature of the low temperature annealing cycle is about 8
It is 0 min, and it can be seen that the time is shortened to about 1/2 of the conventional example.
【0015】[0015]
【発明の効果】本発明によれば、高温から低温への焼鈍
サイクルの変更が短時間で可能になり、生産効率が向上
するという著しい効果を得ることができる。According to the present invention, the annealing cycle can be changed from a high temperature to a low temperature in a short time, and the remarkable effect of improving the production efficiency can be obtained.
【図1】焼鈍炉の降下速度に及ぼす燃焼用空気流量、燃
焼用空気温度の影響を示すグラフである。FIG. 1 is a graph showing influences of a combustion air flow rate and a combustion air temperature on a descent rate of an annealing furnace.
【図2】本発明の実施に好適な連続焼鈍炉における燃料
ガス・燃料用空気の燃料系統概念図である。FIG. 2 is a fuel system conceptual diagram of fuel gas / fuel air in a continuous annealing furnace suitable for implementing the present invention.
【図3】実施例、従来例における炉温の変化を示すグラ
フである。FIG. 3 is a graph showing changes in furnace temperature in Examples and Conventional Examples.
1 排ガス用ファン 2 レキュペレータ 3 ボイラ 4 切換弁 4a 切換弁 4b 切換弁 5 燃焼空気用ファン 6 連続焼鈍炉 7 冷却帯 9 鋼帯 10 排ガス 11 配管 12 バーナ 13 燃焼ガス 14 燃焼用空気 15a 流量制御弁 15b 流量制御弁 1 exhaust gas fan 2 recuperator 3 boiler 4 switching valve 4a switching valve 4b switching valve 5 combustion air fan 6 continuous annealing furnace 7 cooling zone 9 steel strip 10 exhaust gas 11 piping 12 burner 13 combustion gas 14 combustion air 15a flow control valve 15b Flow control valve
───────────────────────────────────────────────────── フロントページの続き (72)発明者 都築 聡 千葉県千葉市中央区川崎町1番地 川崎製 鉄株式会社千葉製鉄所内 (72)発明者 斉藤 洋 千葉県千葉市中央区川崎町1番地 川崎製 鉄株式会社千葉製鉄所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Tsuzuki 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Chiba Works (72) Inventor Hiroshi Saito 1 Kawasaki-cho, Chuo-ku, Chiba Chiba Chiba Steel Works, Ltd.
Claims (2)
イクルから低温焼鈍サイクルへの変更に際し、燃焼継続
が可能な最低量の燃焼ガスを、低温の燃焼用空気ととも
に、燃焼バーナに供給して、炉温を急速に低温焼鈍サイ
クルの設定温度とすることを特徴とする連続焼鈍炉の操
業方法。1. In a direct-fired continuous annealing furnace, at the time of changing from a high temperature annealing cycle to a low temperature annealing cycle, a minimum amount of combustion gas capable of continuing combustion is supplied to a combustion burner together with low temperature combustion air. A method for operating a continuous annealing furnace, wherein the furnace temperature is rapidly set to a set temperature for a low temperature annealing cycle.
気で、その供給量を空気比で 8.0以上とすることを特徴
とする連続焼鈍炉の操業方法。2. A method for operating a continuous annealing furnace, wherein the combustion air is air having a temperature of 250 ° C. or less, and the supply amount is 8.0 or more in an air ratio.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP6426596A JPH09256072A (en) | 1996-03-21 | 1996-03-21 | Operation of continuous annealing furnace |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP6426596A JPH09256072A (en) | 1996-03-21 | 1996-03-21 | Operation of continuous annealing furnace |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH09256072A true JPH09256072A (en) | 1997-09-30 |
Family
ID=13253210
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP6426596A Pending JPH09256072A (en) | 1996-03-21 | 1996-03-21 | Operation of continuous annealing furnace |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH09256072A (en) |
-
1996
- 1996-03-21 JP JP6426596A patent/JPH09256072A/en active Pending
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