JPS6257693B2 - - Google Patents
Info
- Publication number
- JPS6257693B2 JPS6257693B2 JP23287483A JP23287483A JPS6257693B2 JP S6257693 B2 JPS6257693 B2 JP S6257693B2 JP 23287483 A JP23287483 A JP 23287483A JP 23287483 A JP23287483 A JP 23287483A JP S6257693 B2 JPS6257693 B2 JP S6257693B2
- Authority
- JP
- Japan
- Prior art keywords
- preheating
- gas
- steel strip
- zone
- 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.)
- Expired
Links
- 239000007789 gas Substances 0.000 claims description 88
- 229910000831 Steel Inorganic materials 0.000 claims description 65
- 239000010959 steel Substances 0.000 claims description 65
- 238000010438 heat treatment Methods 0.000 claims description 38
- 238000002485 combustion reaction Methods 0.000 claims description 20
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 16
- 229910052760 oxygen Inorganic materials 0.000 claims description 16
- 239000001301 oxygen Substances 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 7
- 230000003647 oxidation Effects 0.000 claims description 6
- 238000007254 oxidation reaction Methods 0.000 claims description 6
- 239000000446 fuel Substances 0.000 description 9
- 239000000567 combustion gas Substances 0.000 description 4
- 238000000137 annealing Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000010731 rolling oil Substances 0.000 description 1
Classifications
-
- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/54—Furnaces for treating strips or wire
- C21D9/56—Continuous furnaces for strip or wire
- C21D9/561—Continuous furnaces for strip or wire with a controlled atmosphere or vacuum
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
Description
【発明の詳細な説明】
この発明は、加熱炉の直火加熱帯で鋼ストリツ
プを予熱したあとの燃焼排ガスによる鋼ストリツ
プの予熱方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preheating a steel strip using flue gas after the steel strip has been preheated in an open heating zone of a heating furnace.
鋼ストリツプを直火式加熱炉で加熱する場合、
鋼ストリツプの過度な酸化を防ぐために、燃料を
空燃比１未満で燃焼させた燃焼ガスが使用されて
いる。燃焼ガスは燃料の未燃分を含有しているの
で、この未燃分による潜熱および鋼ストリツプ加
熱後の燃焼排ガスを有する熱（顕熱）を利用し
て、鋼ストリツプを予熱することが行なわれてい
る。第１図は、このような予熱を行なえるように
した横型直火炉を示したもので、連続亜鉛メツキ
ライン等の焼鈍炉として多用されている。 When heating steel strip in a direct-fired furnace,
To prevent excessive oxidation of the steel strip, combustion gases are used in which the fuel is combusted at an air/fuel ratio of less than 1. Since the combustion gas contains unburned fuel, the steel strip is preheated by using the latent heat of this unburned content and the heat (sensible heat) of the combustion exhaust gas after heating the steel strip. ing. FIG. 1 shows a horizontal direct-fired furnace capable of performing such preheating, which is often used as an annealing furnace for continuous galvanizing lines and the like.
第１図において１は加熱炉の直火加熱帯で、直
火加熱帯１のバーナ２に供給される燃料は、空燃
比0.7〜0.8で燃焼されており、燃焼ガス中には10
〜15％未燃分（H2，CO）が含有されている。直
火加熱帯１で鋼ストリツプ３を加熱した後の高温
の燃焼排ガスは、直火加熱帯１手前のアフターバ
ーニング帯４へ入り、アフターバーニング帯４へ
供給された空気によつて未燃分が燃焼される。未
燃分が燃焼された燃焼排ガスは、予熱ガスとして
アフターバーニング帯４手前の予熱帯５に入り、
そこで鋼ストリツプ３の予熱を行なう。このよう
な予熱帯５における予熱および直火加熱帯１にお
ける加熱によつて、鋼ストリツプ３は700℃程度
まで加熱され、次いで還元帯６に入つて、そこで
高温の還元性ガス（N2と５〜10％のH2とからな
る混合ガス）によつて、表面の還元と燃鈍とが行
なわれる。一方予熱帯５において、鋼ストリツプ
３を予熱した後の予熱排ガスは、予熱帯５からレ
キユペレータ７に入り、そこで直火加熱帯１のバ
ーナ２へ供給する空気を加熱したのち、排ガスと
して炉圧制御ダンパ８を経て大気中に放出され
る。 In Fig. 1, reference numeral 1 indicates a direct-fired heating zone of the heating furnace, and the fuel supplied to the burner 2 of the direct-fired heating zone 1 is burned at an air-fuel ratio of 0.7 to 0.8, and the combustion gas contains 10
Contains ~15% unburned matter (H 2 , CO). The high-temperature combustion exhaust gas after heating the steel strip 3 in the direct-fired heating zone 1 enters the afterburning zone 4 before the direct-fired heating zone 1, and the unburned gas is removed by the air supplied to the afterburning zone 4. be burned. The combustion exhaust gas in which unburned components have been burned enters the preheating zone 5 before the afterburning zone 4 as a preheating gas.
The steel strip 3 is then preheated. By such preheating in the preheating zone 5 and heating in the direct flame heating zone 1, the steel strip 3 is heated to about 700°C, and then enters the reduction zone 6, where it is exposed to hot reducing gases (N 2 and 5 Reduction and annealing of the surface is carried out with a gas mixture consisting of ~10% H 2 ). On the other hand, in the preheating zone 5, the preheated exhaust gas after preheating the steel strip 3 enters the requilifier 7 from the preheating zone 5, where it heats the air supplied to the burner 2 of the direct-fired heating zone 1, and then controls the furnace pressure as exhaust gas. It passes through the damper 8 and is released into the atmosphere.
ところで、直火加熱帯１から排出された燃焼排
ガス中の未燃分を燃焼するために、アフターバー
ニング帯４で必要とする空気量の設定は、直火加
熱帯１のバーナ２への燃料供給量および空気供給
量とから、燃焼排ガス中の未燃分を算出すること
によつて行なわれている。しかしながら、燃料の
成分は、一般に時間的に変動するものであり、上
述のような空気量の設定では、アフターバーニン
グ帯４で必要とする空気量を適切に設定すること
が難しい。そのために、アフターバーニング帯４
から予熱帯５へ入る予熱ガスは、多量の酸素また
は未燃分を含む場合がある。予熱ガス中に多量の
酸素が含まれていると、予熱帯５における過度の
予熱によつて鋼ストリツプ３の表面が著しく酸化
する。一般に、予熱帯における鋼ストリツプ３の
予熱温度は、鋼ストリツプ３の表面の著しい酸化
を防ぐために、予熱ガス中の酸素が１〜３％の場
合で約270℃、酸素がほぼ０近くの場合で約400℃
となすことが必要である。従つて、鋼ストリツプ
３の表面温度（予熱温度）を測定しながら表面温
度を過度に高くならないように鋼ストリツプ３を
予熱すれば、鋼ストリツプ３の過酸化を防ぐこと
が可能となる。しかしながら、このような温度域
の鋼ストリツプは、表面の輻射率が一定でなく、
輻射温度計によつても、その表面温度を精度良く
測定できないため、表面温度の測定によつて鋼ス
トリツプ３の過酸化を防いで予熱することは、従
来不可能であつた。 By the way, the setting of the amount of air required in the afterburning zone 4 in order to burn the unburned content in the combustion exhaust gas discharged from the direct flame heating zone 1 depends on the fuel supply to the burner 2 of the direct flame heating zone 1. This is done by calculating the unburned content in the combustion exhaust gas from the amount of air supplied and the amount of air supplied. However, the components of fuel generally change over time, and it is difficult to appropriately set the amount of air required in the afterburning zone 4 by setting the amount of air as described above. For that purpose, afterburning zone 4
The preheating gas entering the preheating zone 5 may contain a large amount of oxygen or unburned matter. If the preheating gas contains a large amount of oxygen, the surface of the steel strip 3 will be significantly oxidized due to excessive preheating in the preheating zone 5. Generally, the preheating temperature of the steel strip 3 in the preheating zone is approximately 270°C when the oxygen content in the preheating gas is 1 to 3%, and approximately 270°C when the oxygen content is close to 0, in order to prevent significant oxidation of the surface of the steel strip 3. Approximately 400℃
It is necessary to do so. Therefore, overoxidation of the steel strip 3 can be prevented by measuring the surface temperature (preheating temperature) of the steel strip 3 and preheating the steel strip 3 so that the surface temperature does not become excessively high. However, the surface emissivity of steel strips in this temperature range is not constant;
Conventionally, it has been impossible to prevent overoxidation and preheat the steel strip 3 by measuring the surface temperature, since the surface temperature cannot be measured with high accuracy even with a radiation thermometer.
この発明は、上述の現状に鑑み、予熱ガスによ
る鋼ストリツプの過度の予熱を防いで、鋼ストリ
ツプの酸化を防止した、鋼ストリツプの予熱方法
を提供するもので、加熱炉の直火加熱帯で鋼スト
リツプを加熱した後の高温の燃焼排ガスに空気を
導き、前記空気によつて前記燃焼排ガス中の未燃
分を燃焼させ、前記燃焼排ガスによつて前記鋼ス
トリツプを予熱するための予熱ガスを調製し、前
記予熱ガスを前記加熱炉の予熱帯に導いて鋼スト
リツプを予熱する鋼ストリツプの予熱方法におい
て、前記予熱ガスを調製するためのアフターバー
ニング室を前記加熱炉とは別に独立して設け、前
記予熱ガス中の酸素濃度が一定の小さい値となる
ように、前記アフターバーニング室へ空気を供給
して前記燃焼排ガス中の未燃分を完全燃焼させ、
かつ、前記アフターバーニング室から前記予熱帯
へ導かれる前記予熱ガスの量を調節することによ
つて、前記予熱帯において前記予熱ガスにより予
熱される鋼ストリツプの予熱温度を制御し、前記
予熱ガス中の酸素による前記鋼ストリツプの過度
の酸化を防止したことに特徴を有する。 In view of the above-mentioned current situation, the present invention provides a method for preheating a steel strip that prevents excessive preheating of the steel strip by preheating gas and prevents oxidation of the steel strip. Air is introduced into the high temperature combustion exhaust gas after heating the steel strip, the unburned content in the combustion exhaust gas is combusted by the air, and the steel strip is preheated by the combustion exhaust gas. In the method for preheating a steel strip, the preheating gas is introduced into a preheating zone of the heating furnace to preheat the steel strip, and an afterburning chamber for preparing the preheating gas is provided independently from the heating furnace. , supplying air to the afterburning chamber to completely burn the unburned content in the combustion exhaust gas so that the oxygen concentration in the preheated gas is a constant small value;
and controlling the preheating temperature of the steel strip preheated by the preheating gas in the preheating zone by adjusting the amount of the preheating gas led from the afterburning chamber to the preheating zone; The steel strip is characterized in that excessive oxidation of the steel strip by oxygen is prevented.
以下、この発明の方法を図面に基づき詳述す
る。第２図は、この発明に用いられる縦型の直火
加熱炉を示す部分断面図である。第２図において
１０はアフターバーニング室で、この発明では、
加熱炉本体１１とは別に独立して設けられた、ア
フターバーニング室１０において、直火加熱帯１
２から排出された燃焼排ガス中の未燃分を完全燃
焼させて予熱ガスとすると共に、アフターバーニ
ング室１０から予熱帯１３へ導かれる予熱ガスの
量を制御して、予熱帯１３における鋼ストリツプ
１４の過度の予熱を防止するようにした。 Hereinafter, the method of the present invention will be explained in detail based on the drawings. FIG. 2 is a partial sectional view showing a vertical direct-fired heating furnace used in the present invention. In FIG. 2, 10 is an afterburning chamber, and in this invention,
In the afterburning chamber 10, which is provided independently from the heating furnace main body 11, a direct heating zone 1 is provided.
The unburned content in the combustion exhaust gas discharged from the combustion exhaust gas 2 is completely combusted to become preheated gas, and the amount of preheated gas led from the afterburning chamber 10 to the preheating zone 13 is controlled to control the steel strip 14 in the preheating zone 13. This prevents excessive preheating.
図示されるように、直火加熱帯１２から排出さ
れた燃焼排ガスは、アフターバーニング室１０へ
導かれ、アフターバーニング室１０へ供給された
空気によつて含有している未燃分が燃焼される。
ここで、アフターバーニング室１０へ供給する空
気量は、未燃分が燃焼されたあとの燃焼排ガス
（予熱ガス）の酸素濃度が一定の小さな値、例え
ば1.0〜1.5％程度となるように設定する。そのた
めに、予熱ガスの酸素濃度を測定し、その測定値
に基いて空気量を設定する。アフターバーニング
室１０において未燃分が燃焼された燃焼排ガス
は、予熱ガスとしてその一部又は全部が予熱帯１
３の鋼ストリツプ出口側から予熱帯１３へ導か
れ、予熱帯１３内を通る鋼ストリツプ１４を所定
温度まで予熱する。この鋼ストリツプ１４の予熱
温度制御については後述する。予熱ガスの残り
は、アフターバーニング室１０から予熱帯バイパ
スダンパ１５を経てレキユペレータ１６へ導かれ
る。鋼ストリツプ１４を予熱したあとの予熱排ガ
スは、予熱帯１３の鋼ストリツプ入口側から排出
されて、予熱帯排気ダンパ１７を経てレキユペレ
ータ１６へ導かれ、そこで直火加熱帯１２のバー
ナ１８とアフターバーニング室１０とへ供給する
空気を加熱したのち、炉圧制御ダンパ１９を経て
大気中へ放出される。なお２０は排気フアンであ
る。 As shown in the figure, the combustion exhaust gas discharged from the open heating zone 12 is guided to the afterburning chamber 10, and the unburned content contained therein is burned by the air supplied to the afterburning chamber 10. .
Here, the amount of air supplied to the afterburning chamber 10 is set so that the oxygen concentration of the combustion exhaust gas (preheated gas) after the unburned components are combusted is a constant small value, for example, about 1.0 to 1.5%. . For this purpose, the oxygen concentration of the preheating gas is measured, and the amount of air is set based on the measured value. The combustion exhaust gas, in which unburned components are burned in the afterburning chamber 10, is partially or completely transferred to the preheating zone 1 as a preheating gas.
The steel strip 14 is led from the exit side of the steel strip 3 to the preheating zone 13, and the steel strip 14 passing through the preheating zone 13 is preheated to a predetermined temperature. Control of the preheating temperature of the steel strip 14 will be described later. The remainder of the preheating gas is guided from the afterburning chamber 10 to the recuperator 16 via the preheating zone bypass damper 15. The preheated exhaust gas after preheating the steel strip 14 is discharged from the steel strip inlet side of the preheating zone 13 and guided to the recuperator 16 via the preheating zone exhaust damper 17, where it is connected to the burner 18 of the direct heating zone 12 and afterburning. After the air supplied to the chamber 10 is heated, it is discharged into the atmosphere through the furnace pressure control damper 19. Note that 20 is an exhaust fan.
予熱帯１３において所定温度まで予熱された鋼
ストリツプ１４は、直火加熱帯１２へ入り、そこ
でバーナ１８から噴射される空燃比0.8〜0.95で
燃焼された燃焼ガスによつて、600〜750℃まで加
熱される。この加熱によつて、鋼ストリツプ１４
は、表面に付着した圧延油等の除去と表面の部分
還元が同時に行なわれる。直火加熱帯１２から排
出された燃焼排ガスは、５〜８％の未燃分を含ん
でおり、上述したようにアフターバーニング室１
０へ導かれて未燃分の燃焼が行なわれる。直火加
熱帯１２を出た鋼ストリツプ１４は、次いで還元
帯２１へ入り、そこで温度700〜900℃の高温の還
元性ガス（N2と５〜10％のH2ガスとからなる混
合ガス）によつて、表面の完全な還元と焼鈍とが
行なわれる。 The steel strip 14, which has been preheated to a predetermined temperature in the preheating zone 13, enters the direct heating zone 12, where it is heated to a temperature of 600 to 750°C by the combustion gas injected from the burner 18 and combusted at an air-fuel ratio of 0.8 to 0.95. heated. This heating causes the steel strip 14 to
In this method, removal of rolling oil etc. adhering to the surface and partial reduction of the surface are performed at the same time. The combustion exhaust gas discharged from the direct fire heating zone 12 contains 5 to 8% unburned matter, and as described above, the afterburning chamber 1
0, and the unburned matter is burned. The steel strip 14 leaving the open heating zone 12 then enters the reduction zone 21 where it is exposed to a hot reducing gas (mixture of N 2 and 5 to 10% H 2 gas) at a temperature of 700-900°C. This results in complete reduction and annealing of the surface.
次に、予熱帯１３において予熱される鋼ストリ
ツプ１４の予熱温度制御について述べる。前述し
たように、鋼ストリツプ１４の温度は、輻射温度
計など現在の技術での非接触型温度計によつて測
定することが困難である。そこで、この発明で
は、以下のようにして鋼ストリツプ１４の予熱温
度制御を行なう。 Next, the preheating temperature control of the steel strip 14 preheated in the preheating zone 13 will be described. As previously mentioned, the temperature of the steel strip 14 is difficult to measure with current technology non-contact thermometers, such as radiant thermometers. Therefore, in the present invention, the preheating temperature of the steel strip 14 is controlled as follows.
すなわち、温度計T1を予熱帯１３入口手前の
ガス通路に、温度計T2を予熱帯排気ダンパ１７
手前のガス通路に、温度計T3を予熱帯バイパス
ダンパ１５の先のガス通路に、温度計T4をレキ
ユペレータ１６手前のガス通路に設け、それぞれ
の通路を通る予熱ガスの温度を測定する。今、温
度計T1，T2，T3およびT4によつて測定された予
熱ガスの温度を、それぞれt1，t2，t3およびt4
（℃）とし、温度t1，t2，t3およびt4における予熱
ガスの平均比熱をC1，C2，C3およびC4（kcal／
Ｎm3．℃）とし、予熱帯１３を通過する予熱ガス
量（以下通過ガス量と称す）をVr、予熱帯１３
のバイパスを通過する予熱ガス量（以下バイパス
量と称す）Vb、レキユペレータ１６へ入る予熱
ガス量（以下全予熱ガス量と称す）をVt（Ｎ
m3／ｈ）とする。予熱帯１３から放散によつて失
なわれる熱量は、予熱帯１３を通る予熱ガスが有
する熱量の1.5〜２％程度と少ないから、予熱ガ
スについて、実用上充分な精度で、次の熱収支お
よびガス収支の式が成立する。 That is, the thermometer T 1 is placed in the gas passage before the inlet of the preheating area 13, and the thermometer T 2 is placed in the gas passage before the preheating area exhaust damper 17.
A thermometer T 3 is installed in the gas passage in front of the preheating zone bypass damper 15, and a thermometer T 4 is installed in the gas passage in front of the recuperator 16 to measure the temperature of the preheated gas passing through each passage. Now let the temperature of the preheated gas measured by thermometers T 1 , T 2 , T 3 and T 4 be t 1 , t 2 , t 3 and t 4 respectively.
(℃), and the average specific heat of the preheated gas at temperatures t 1 , t 2 , t 3 and t 4 is C 1 , C 2 , C 3 and C 4 (kcal/
Nm3 . ℃), and the amount of preheated gas passing through the preheating zone 13 (hereinafter referred to as passing gas amount) is Vr, and the amount of preheating gas passing through the preheating zone 13 is Vr.
The amount of preheated gas passing through the bypass (hereinafter referred to as the bypass amount) is Vb, and the amount of preheated gas entering the recuperator 16 (hereinafter referred to as the total amount of preheated gas) is Vt (N
m 3 /h). Since the amount of heat lost by radiation from the preheating zone 13 is as small as about 1.5 to 2% of the amount of heat possessed by the preheating gas passing through the preheating zone 13, the following heat balance and The gas balance equation is established.
ガス収支：Vr＋Vb＝Vt ……
熱収支：VrC2t2＋VbC3t3＝VtC4t4 ……
この，式のうち、全予熱ガス量Vtは、直
火加熱帯１２のバーナ１８への燃料供給量とアフ
ターバーニング室１０での未燃分燃焼後の予熱ガ
ス中の酸素濃度とから算出することができる。従
つて、，式より、通過ガス量Vrとバイパス
ガス量Vbとが求まる。 Gas balance: Vr + Vb = Vt ... Heat balance: VrC 2 t 2 + VbC 3 t 3 = VtC 4 t 4 ... In this equation, the total preheating gas amount Vt is the fuel to the burner 18 of the direct heating zone 12 It can be calculated from the supply amount and the oxygen concentration in the preheated gas after combustion of unburned components in the afterburning chamber 10. Therefore, the amount of passing gas Vr and the amount of bypass gas Vb can be determined from the formula.
次に、鋼ストリツプ１４の予熱帯入口温度をτ
１、予熱帯出口温度をτ２（℃）とし、鋼ストリ
ツプ１４の単位時間当りの予熱帯通過量をＷ
（Kg／ｈ）、鋼ストリツプ１４の比熱をＣ（kacl／
Kg・℃）とすると、予熱帯１３において鋼ストリ
ツプ１４が得た熱量と予熱ガスが失なつた熱量と
は等しいことから、次の熱収支の式が成立する。 Next, the temperature at the inlet of the preheating zone of the steel strip 14 is set to τ
1. The temperature at the outlet of the preheating zone is τ 2 (°C), and the amount of steel strip 14 passing through the preheating zone per unit time is W.
(Kg/h), and the specific heat of the steel strip 14 is C (kacl/h).
Kg·°C), the amount of heat gained by the steel strip 14 in the preheating zone 13 is equal to the amount of heat lost by the preheating gas, so the following heat balance equation holds true.
WC（τ２−τ１）＝Vr（C1t1−C2t2） ……
この式のうち、Vrは前記，式より求ま
り、Ｗ，Ｃ，τ１，C1，C2，t1およびt2は既知な
ので、未知数τ２が求まる。すなわち、ある通過
ガス量Vrのときに、予熱帯１３に入る予熱ガス
の温度t1、予熱帯１３から出る予熱ガスの温度は
t2、予熱帯１３のバイパス予熱ガスの温度t3、レ
キユペレータ１６に入る予熱ガスの温度t4とアフ
ターバーニング室１０から出る予熱ガス中の酸素
濃度とを測定することによつて、前記ガス収支の
式、熱収支の式およびから、鋼ストリツプ
１４の予熱温度τ２が求まる。なお、このように
して求められた鋼ストリツプ１４の予熱温度τ２
は、予熱ガスの熱容量が鋼ストリツプ１４の熱容
量の約半分程度であり、予熱ガスの温度変化は鋼
ストリツプ１４の温度変化より約２倍大きくなる
ので、鋼ストリツプ１４の予熱温度を直接測定し
たものより精度がよい。 WC (τ 2 - τ 1 ) = Vr (C 1 t 1 - C 2 t 2 )... In this equation, Vr is found from the above equation, and W, C, τ 1 , C 1 , C 2 , t Since 1 and t 2 are known, the unknown τ 2 can be found. That is, at a certain passing gas amount Vr, the temperature t 1 of the preheated gas entering the preheating zone 13 and the temperature of the preheating gas leaving the preheating zone 13 are
t 2 , the temperature t 3 of the bypass preheating gas in the preheating zone 13 , the temperature t 4 of the preheating gas entering the recuperator 16 , and the oxygen concentration in the preheating gas exiting from the afterburning chamber 10 . The preheating temperature τ 2 of the steel strip 14 is determined from the equation , the heat balance equation, and the equation. Note that the preheating temperature τ 2 of the steel strip 14 determined in this way
is a direct measurement of the preheating temperature of the steel strip 14, since the heat capacity of the preheating gas is about half that of the steel strip 14, and the temperature change of the preheating gas is about twice as large as the temperature change of the steel strip 14. More accurate.
従つて、この発明では、予熱ガスについての前
記温度t1〜t4を測定し、これと予熱ガスについて
測定された酸素濃度とから鋼ストリツプ１４の予
熱温度τ２を求めながら、予熱帯バイパスダンパ
１５の開度を調整してバイパスガス量Vb、予熱
帯通過ガス量Vrを制御し、鋼ストリツプ１４の
予熱温度τ２を、前記予熱ガス中の酸素によつて
鋼ストリツプ１４が過度に酸化されない適正温度
に制御する。 Therefore, in the present invention, the temperatures t1 to t4 of the preheating gas are measured, and the preheating temperature τ2 of the steel strip 14 is determined from this and the oxygen concentration measured for the preheating gas. 15 to control the amount of bypass gas Vb and the amount of gas passing through the preheating zone Vr, and set the preheating temperature τ2 of the steel strip 14 so that the steel strip 14 is not excessively oxidized by the oxygen in the preheating gas. Control the temperature to an appropriate level.
以上説明したように、この発明によれば、加熱
炉本体とは別に独立してアフターバーニング室を
設け、アフターバーニング室において、予熱ガス
中の酸素濃度が一定の小さな値となるように空気
を供給して、燃焼排ガス中の未燃分を完全燃焼さ
せ、かつ、予熱帯へ導く予熱ガスの量を調節し
て、予熱ガスによる鋼ストリツプの予熱温度を、
予熱ガス中の酸素によつて鋼ストリツプが過度に
酸化されない適正温度に制御しているので、予熱
ガスによつて鋼ストリツプに過度の酸化を生ずる
ことなく、鋼ストリツプを予熱することができ
る。 As explained above, according to the present invention, an afterburning chamber is provided independently from the heating furnace main body, and air is supplied in the afterburning chamber so that the oxygen concentration in the preheating gas becomes a constant small value. Then, the unburned content in the combustion exhaust gas is completely combusted, and the amount of preheating gas guided to the preheating zone is adjusted, so that the temperature at which the steel strip is preheated by the preheating gas is
The steel strip can be preheated without causing excessive oxidation of the steel strip by the preheating gas, since the temperature is controlled to an appropriate temperature so that the steel strip is not excessively oxidized by the oxygen in the preheating gas.
第１図は、従来の直火型加熱炉の部分断面図、
第２図は、この発明に用いられる直火加熱炉の部
分断面図である。図面において、
１０…アフターバーニング室、１１…加熱炉本
体、１２…直火加熱帯、１３…予熱帯、１４…鋼
ストリツプ、１５，１７，１９…ダンパ、１６…
レキユペレータ、１８…バーナ、T1〜T4…温度
計。
Figure 1 is a partial cross-sectional view of a conventional direct-fired heating furnace.
FIG. 2 is a partial sectional view of the direct-fired heating furnace used in the present invention. In the drawings, 10... afterburning chamber, 11... heating furnace main body, 12... direct flame heating zone, 13... preheating zone, 14... steel strip, 15, 17, 19... damper, 16...
Recuperator, 18...Burner, T1 to T4 ...Thermometer.
Claims (1)
た後の高温の燃焼排ガスに空気を導き、前記空気
によつて前記燃焼排ガス中の未燃分を燃焼させ、
前記燃焼排ガスによつて前記鋼ストリツプを予熱
するための予熱ガスを調製し、前記予熱ガスを前
記加熱炉の予熱帯に導いて鋼ストリツプを予熱す
る鋼ストリツプの予熱方法において、 前記予熱ガスを調製するためのアフターバーニ
ング室を前記加熱炉とは別に独立して設け、前記
予熱ガス中の酸素濃度が一定の小さい値となるよ
うに、前記アフターバーニング室へ空気を供給し
て前記燃焼排ガス中の未燃分を完全燃焼させ、か
つ、前記アフターバーニング室から前記予熱帯へ
導かれる前記予熱ガスの量を調節することによつ
て、前記予熱帯において、前記予熱ガスにより予
熱される鋼ストリツプの予熱温度を制御し、前記
予熱ガス中の酸素による前記鋼ストリツプの過度
の酸化を防止したことを特徴とする鋼ストリツプ
の予熱方法。[Scope of Claims] 1. Introducing air into high-temperature combustion exhaust gas after heating a steel strip in a direct heating zone of a heating furnace, and causing unburned content in the combustion exhaust gas to be combusted by the air,
A method for preheating a steel strip, wherein a preheating gas for preheating the steel strip is prepared using the combustion exhaust gas, and the preheating gas is introduced into a preheating zone of the heating furnace to preheat the steel strip, comprising: preparing the preheating gas. An afterburning chamber is provided separately from the heating furnace, and air is supplied to the afterburning chamber so that the oxygen concentration in the preheated gas is kept at a constant small value. Preheating the steel strip to be preheated by the preheating gas in the preheating zone by completely combusting unburned content and adjusting the amount of the preheating gas led from the afterburning chamber to the preheating zone. A method for preheating a steel strip, characterized in that the temperature is controlled to prevent excessive oxidation of the steel strip by oxygen in the preheating gas.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23287483A JPS60125330A (en) | 1983-12-12 | 1983-12-12 | Preheating method of steel strip |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23287483A JPS60125330A (en) | 1983-12-12 | 1983-12-12 | Preheating method of steel strip |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60125330A JPS60125330A (en) | 1985-07-04 |
| JPS6257693B2 true JPS6257693B2 (en) | 1987-12-02 |
Family
ID=16946180
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23287483A Granted JPS60125330A (en) | 1983-12-12 | 1983-12-12 | Preheating method of steel strip |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60125330A (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6345323A (en) * | 1986-08-11 | 1988-02-26 | Mitsubishi Heavy Ind Ltd | Metallic strip heater |
| JPS6345324A (en) * | 1986-08-11 | 1988-02-26 | Mitsubishi Heavy Ind Ltd | Heating of metallic strip |
| JPH086146B2 (en) * | 1989-05-24 | 1996-01-24 | 日本鋼管株式会社 | Rigid open flame heating furnace |
| JP2853493B2 (en) * | 1992-11-25 | 1999-02-03 | 日本鋼管株式会社 | Method and apparatus for heating steel strip in continuous annealing furnace |
| CN102445087B (en) * | 2011-12-01 | 2013-07-03 | 天津钢管集团股份有限公司 | Method for adopting high-temperature smoke discharged from rotary heating furnace as preheating heat source for mandril |
| MX2023003311A (en) * | 2020-09-23 | 2023-04-13 | Fives Stein | Direct flame preheating section for a continuous metal strip processing line. |
| FR3114324B1 (en) * | 2020-09-23 | 2022-12-16 | Fives Stein | DIRECT FLAME PREHEATING SECTION FOR CONTINUOUS METAL STRIP TREATMENT LINE |
-
1983
- 1983-12-12 JP JP23287483A patent/JPS60125330A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60125330A (en) | 1985-07-04 |
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