JP2009155691A - Direct-fire type roller hearth continuous heat-treatment furnace - Google Patents

Direct-fire type roller hearth continuous heat-treatment furnace Download PDF

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JP2009155691A
JP2009155691A JP2007335165A JP2007335165A JP2009155691A JP 2009155691 A JP2009155691 A JP 2009155691A JP 2007335165 A JP2007335165 A JP 2007335165A JP 2007335165 A JP2007335165 A JP 2007335165A JP 2009155691 A JP2009155691 A JP 2009155691A
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combustion control
heat treatment
burner
temperature
furnace
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JP4987689B2 (en
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Toshiaki Saito
俊明 齋藤
Daisuke Watanabe
大介 渡辺
Motohiro Osada
元宏 長田
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Nippon Steel Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a direct-fire type roller hearth continuous heat-treatment furnace which can provide a desirable material in an adequate treatment period of time, through uniformly heating the article to be heat-treated by improving the uniformity of a temperature distribution in the furnace. <P>SOLUTION: The direct-fire type roller hearth continuous heat-treatment furnace 1 which has spaces inside the furnace partitioned into a plurality of combustion control zones in a transporting direction of the article to be heat-treated and has a thinning-out combustion function as a combustion control function has: burners 4 with relatively low discharging flow rates arranged in combustion control zones in a lower side of a transport roll R among combustion control zones in a prior stage, which heat the article to be heat-treated S almost to a treatment temperature, and combustion control zones in a posterior stage, which keep the temperature of the article to be heat-treated approximately at the treatment temperature; and burners with relatively high discharging flow rates arranged in combustion control zones in the upper side of the transport roll R among the combustion control zones in the posterior stage, which keep the temperature of the article to be heat-treated approximately at the treatment temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、金属の熱処理炉に関するものであって、特に、直火型ローラーハース式連続熱処理炉のバーナ構成に関するものである。   The present invention relates to a metal heat treatment furnace, and more particularly to a burner configuration of a direct-fired roller hearth type continuous heat treatment furnace.

金属材料製造においては所望の材質特性を得るために材料に熱処理を施している。さまざまな条件下での熱処理により強度や靭性などの特性値を所望の値に制御している。熱処理における材料の加熱には燃焼加熱方式や誘導加熱方式が用いられるが、コスト面での優位性から燃焼加熱方式による熱処理炉が広く普及している。鉄鋼業のような大量生産プロセスにおいては燃焼加熱方式の連続熱処理炉が主流で、特に、厚鋼板や鋼管の熱処理には炉長が数十ｍ規模のローラーハース式の連続熱処理炉がよく用いられる。   In manufacturing a metal material, the material is subjected to heat treatment in order to obtain desired material characteristics. Characteristic values such as strength and toughness are controlled to desired values by heat treatment under various conditions. Although a combustion heating method or an induction heating method is used for heating the material in the heat treatment, a heat treatment furnace using a combustion heating method is widely spread because of cost advantage. In mass production processes such as the steel industry, the combustion heat type continuous heat treatment furnace is the mainstream, and in particular, a roller hearth type continuous heat treatment furnace with a furnace length of several tens of meters is often used for heat treatment of thick steel plates and steel pipes. .

燃焼加熱方式にも直接加熱となる直火式と間接加熱となるラジアントチューブ式とがあり、これらは主に雰囲気制御の必要性から使い分けられている。高温処理となり被熱処理材の酸化が顕著になる焼ならし処理炉では、炉内雰囲気を燃焼ガスから遮断するためにラジアントチューブ式が用いられる。一方、雰囲気制御の必要がない焼戻し処理では加熱効率が高い直火式を用いる場合が多い。直火式とラジアントチューブ式の差異は雰囲気制御性や加熱効率のほか、炉内温度分布の均一性に違いがある。一般的に直接加熱である直火式はラジアントチューブ式よりも炉内温度偏差が生じやすい。   Combustion heating methods include a direct fire type for direct heating and a radiant tube type for indirect heating, and these are selectively used mainly for the necessity of atmospheric control. In a normalizing furnace where high-temperature processing is performed and oxidation of the material to be heat-treated becomes remarkable, a radiant tube type is used to block the furnace atmosphere from the combustion gas. On the other hand, in a tempering process that does not require atmosphere control, a direct flame type with high heating efficiency is often used. The difference between the direct fire type and the radiant tube type is that there is a difference in the uniformity of the furnace temperature distribution as well as the atmospheric controllability and heating efficiency. In general, the direct-fire type, which is direct heating, is more likely to cause a furnace temperature deviation than the radiant tube type.

熱処理条件は材料に求められる特性によって変わり、加熱温度やその後の冷却速度が制御される。このような熱処理においては被熱処理材内に温度偏差が生じると所望の特性が得られないことがあるため、均一加熱が重要である。例えば、焼戻し処理においては、目標の処理温度に対してプラスマイナス１０℃程度の範囲で処理することが必要であり、所望の特性が得られることを保証するために、通常は目標処理温度±１０℃の状態を数十分程度保定したのちに処理を完了する。均一加熱能力が不十分な熱処理炉では、被熱処理材の温度均一性を改善するために処理時間を長大にするなどの対策が必要となる。さらに均一性が悪い場合には被熱処理材の一部の部位に所望の材料特性が得られないこともある。   The heat treatment conditions vary depending on the characteristics required for the material, and the heating temperature and the subsequent cooling rate are controlled. In such heat treatment, uniform heating is important because desired characteristics may not be obtained if a temperature deviation occurs in the material to be heat treated. For example, in the tempering process, it is necessary to perform processing within a range of about plus or minus 10 ° C. with respect to the target processing temperature, and in order to ensure that desired characteristics can be obtained, the target processing temperature is usually ± 10. The process is completed after maintaining the temperature at several degrees for several tens of minutes. In heat treatment furnaces with insufficient uniform heating capability, measures such as increasing the treatment time are required to improve the temperature uniformity of the material to be heat treated. Further, when the uniformity is poor, desired material characteristics may not be obtained at some parts of the heat-treated material.

炉内の温度均一性を高めるための一般的な技術としては、炉内ガスを強攪拌するような高速吐出噴流バーナの適用や攪拌用のファンを設置する技術が知られている。また、熱処理炉で多く見られるパルス的な間引き燃焼が発生する状況に対しては、特許文献１にあるように、炉内温度センサーに基づき点火時間を調整しつつ燃焼させるバーナを周期的に順次変更する技術や特許文献２にあるように、燃焼制御帯ごとにバーナのデューティ比を一定の割合で増減させた燃焼パターンをあらかじめ複数設定しておき、炉内温度偏差をセンサーで検出しつつ、所定の温度偏差を超えたときには異なる燃焼パターンに順次切り替える技術が知られている。   As a general technique for increasing the temperature uniformity in the furnace, a technique of applying a high-speed discharge jet burner that strongly stirs the gas in the furnace and installing a stirring fan is known. In addition, for the situation where pulse-like thinning combustion often seen in heat treatment furnaces occurs, as disclosed in Patent Document 1, the burners that are burned while adjusting the ignition time based on the furnace temperature sensor are sequentially and sequentially. As described in the technology to be changed and Patent Document 2, a plurality of combustion patterns in which the duty ratio of the burner is increased or decreased at a constant rate for each combustion control zone are set in advance, and the temperature deviation in the furnace is detected by a sensor. A technique for sequentially switching to different combustion patterns when a predetermined temperature deviation is exceeded is known.

特開平７−２６９８５２号公報JP-A-7-269852 特開平８−７５１５１号公報JP-A-8-75151

しかし上述の従来技術では十分な均一性が得られない場合がある。
高速噴流バーナによる炉内ガスを強攪拌する技術では、バーナ容量と炉幅の関係や隣接するバーナのピッチなどが攪拌力に大きく影響するものの、このような仕様は熱処理条件や熱処理炉の処理能力から定まるものであり、攪拌力に関わるこれらの要素が常に良好に整合するわけではないため、炉内温度分布の均一化がうまく達成できないことがある。ファンなどの駆動装置によるガス攪拌を行う場合では、駆動設備を収容するスペースのために炉が大規模になる問題や、ファンや軸などの駆動装置関連の保守費用が高いなどの経済的な問題が生じる。 However, there are cases where sufficient uniformity cannot be obtained with the above-described conventional technology.
In the technology that stirs the gas in the furnace with a high-speed jet burner, the relationship between the burner capacity and the furnace width and the pitch of the adjacent burner greatly affect the stirring power. Since these factors related to the stirring force do not always match well, it may not be possible to achieve a uniform furnace temperature distribution. When performing gas agitation with a drive unit such as a fan, there are problems such as a problem that the furnace becomes large due to the space for housing the drive facility, and economic problems such as high maintenance costs related to the drive unit such as the fan and shaft Occurs.

また、点火バーナを周期的に順次切り替える技術では、燃焼制御帯のターンダウンが起きても１本あたりのターンダウンが小さく取れるため低燃焼負荷時の炉内温度均一性が維持しやすいものの、バーナ１本ごとの燃料配管と燃焼空気配管の双方に遮断弁を備える必要があり、一般に１００本以上のバーナを配するローラハース式連続熱処理炉では設備費が増大する問題がある。さらに、デューティ比をあらかじめ複数用意して炉内温度偏差により燃焼制御を切り替える手法では、どのようなパターンをあらかじめ用意できるかが重要となるが、デューティ比に限らずあらかじめ燃焼パターンを設定しておくような手法では、多種多様な熱処理条件に対応可能な設定をあらかじめ与えることが難しいために炉内温度分布の均一化がうまく達成できないことがある。   In addition, with the technology of periodically switching the ignition burner, even if the combustion control zone turndown occurs, the turndown per one can be made small, so it is easy to maintain the furnace temperature uniformity at low combustion load. It is necessary to provide a shut-off valve in each fuel pipe and combustion air pipe, and there is a problem that the equipment cost increases in a roller hearth type continuous heat treatment furnace in which 100 or more burners are generally provided. Furthermore, in the method of preparing a plurality of duty ratios in advance and switching the combustion control based on the furnace temperature deviation, it is important what pattern can be prepared in advance. However, not only the duty ratio but also a combustion pattern is set in advance. In such a method, since it is difficult to provide in advance a setting that can cope with various heat treatment conditions, it may be difficult to achieve uniform temperature distribution in the furnace.

本発明は、直火型ローラーハース式連続熱処理炉において、上述のような問題点を解消して炉内温度分布の均一性を向上させることにより、被熱処理材を適正な処理時間で所望の材質を得る簡便な手段を提供することを目的とするものである。   The present invention eliminates the above-mentioned problems and improves the uniformity of the temperature distribution in the furnace in a direct-fired roller hearth type continuous heat treatment furnace. It is an object to provide a simple means for obtaining the above.

第一の発明は、燃焼制御機能として間引き燃焼機能を有する直火型のローラーハース式連続熱処理炉であって、炉内空間が被熱処理材の搬送方向に複数の燃焼制御帯に分割された熱処理炉において、被熱処理材を処理温度近くまで加熱する前段の燃焼制御帯のうち搬送ロールの上側と下側の両方の燃焼制御帯および被熱処理材温度を略処理温度に保定する後段の燃焼制御帯のうち搬送ロールの下側の燃焼制御帯には、吐出流速が相対的に低速なバーナを配し、前記後段の燃焼制御帯のうち搬送ロールの上側の燃焼制御帯には、吐出流速が相対的に高速なバーナを配したことを特徴とする直火型ローラーハース式連続熱処理炉である。   A first invention is a direct-fire type roller hearth type continuous heat treatment furnace having a thinning combustion function as a combustion control function, wherein the furnace space is divided into a plurality of combustion control zones in the conveying direction of the material to be heat treated In the furnace, out of the preceding combustion control zone that heats the heat-treated material to near the processing temperature, both the upper and lower combustion control zones of the transport roll and the subsequent combustion control zone that keeps the temperature of the heat-treated material at the processing temperature. A burner having a relatively low discharge flow rate is disposed in the combustion control zone below the transport roll, and the discharge flow rate is relatively in the combustion control zone above the transport roll in the combustion control zone in the latter stage. It is a direct-fired type roller hearth type continuous heat treatment furnace characterized by a high-speed burner.

第二の発明は、燃焼制御機能として間引き燃焼機能を有する直火型のローラーハース式連続熱処理炉であって、炉内空間が被熱処理材の搬送方向に複数の燃焼制御帯に分割された熱処理炉において、被熱処理材を処理温度近くまで加熱する前段の燃焼制御帯のうち搬送ロールの上側と下側の両方の燃焼制御帯には、吐出流速が相対的に低速なバーナを配し、被熱処理材温度を略処理温度に保定する後段の燃焼制御帯のうち搬送ロールの上側と下側の両方の燃焼制御帯には、吐出流速が相対的に高速なバーナを配したことを特徴とする直火型ローラーハース式連続熱処理炉である。   The second invention is a direct-fire type roller hearth type continuous heat treatment furnace having a thinning combustion function as a combustion control function, wherein the furnace space is divided into a plurality of combustion control zones in the conveying direction of the material to be heat treated In the furnace, both the upper and lower combustion control zones of the previous stage of the combustion control zone that heats the heat-treated material to near the processing temperature are provided with burners having a relatively low discharge flow rate. A burner having a relatively high discharge flow rate is disposed in both the upper and lower combustion control zones of the transport roll in the subsequent combustion control zone that keeps the heat treatment material temperature substantially at the processing temperature. It is a direct fire type roller hearth type continuous heat treatment furnace.

第三の発明は、燃焼制御機能として間引き燃焼機能を有する直火型のローラーハース式連続熱処理炉であって、炉内空間が被熱処理材の搬送方向に複数の燃焼制御帯に分割された熱処理炉において、搬送ロールの下側の燃焼制御帯には吐出流速が相対的に低速なバーナを配し、搬送ロールの上側の燃焼制御帯には吐出流速が相対的に高速なバーナを配したことを特徴とする直火型ローラーハース式連続熱処理炉である。   A third invention is a direct-fire type roller hearth type continuous heat treatment furnace having a thinning combustion function as a combustion control function, wherein the furnace space is divided into a plurality of combustion control zones in the conveying direction of the material to be heat treated In the furnace, a burner with a relatively low discharge flow rate was placed in the combustion control zone below the transfer roll, and a burner with a relatively high discharge flow rate was placed in the combustion control zone above the transfer roll It is a direct fire type roller hearth type continuous heat treatment furnace characterized by

第四の発明は、燃焼制御機能として間引き燃焼機能を有する直火型のローラーハース式連続熱処理炉であって、炉内空間が被熱処理材の搬送方向に複数の燃焼制御帯に分割された熱処理炉において、被熱処理材を処理温度近くまで加熱する前段の燃焼制御帯のうち搬送ロールの下側の燃焼制御帯には、吐出流速が相対的に低速なバーナを配し、被熱処理材温度を略処理温度に保定する後段の燃焼制御帯のうち搬送ロールの上側と下側の両方の燃焼制御帯および前記前段の燃焼制御帯のうち搬送ロールの上側の燃焼制御帯には、吐出流速が相対的に高速なバーナを配したことを特徴とする直火型ローラーハース式連続熱処理炉である。   A fourth invention is a direct-fired roller hearth type continuous heat treatment furnace having a thinning-out combustion function as a combustion control function, wherein the furnace space is divided into a plurality of combustion control zones in the conveying direction of the material to be heat treated In the furnace, a burner with a relatively low discharge flow rate is placed in the combustion control zone below the transport roll in the previous stage combustion control zone that heats the heat-treated material to near the processing temperature, and the temperature of the heat treatment material is The discharge flow rate is relative to the combustion control zone on both the upper and lower sides of the transport roll in the subsequent combustion control zone that is held at substantially the processing temperature, and the combustion control zone on the upper side of the transport roll in the previous combustion control zone. It is a direct-fired type roller hearth type continuous heat treatment furnace characterized by a high-speed burner.

第五の発明は、前記吐出流速が相対的に高速なバーナの吐出口径を、前記吐出流速が相対的に低速なバーナの吐出口径よりも小さくすることを特徴とする上記直火型ローラーハース式連続熱処理炉である。
第六の発明は、前記被熱処理材が鋼材であることを特徴とする上記の直火型ローラーハース式連続熱処理炉である。
第七の発明は、前記鋼材が厚鋼板であることを特徴とする上記の直火型ローラーハース式連続熱処理炉である。
第八の発明は、前記鋼材が鋼管であることを特徴とする上記の直火型ローラーハース式連続熱処理炉である。 The fifth aspect of the present invention is the direct fire type roller hearth type, wherein the discharge port diameter of the burner having a relatively high discharge flow rate is made smaller than the discharge port diameter of the burner having a relatively low discharge flow rate. It is a continuous heat treatment furnace.
6th invention is said direct-fired type | mold roller hearth type | mold continuous heat processing furnace characterized by the above-mentioned to-be-heated material being steel materials.
A seventh invention is the above-mentioned direct-fired roller hearth type continuous heat treatment furnace, wherein the steel material is a thick steel plate.
An eighth invention is the above-described direct-fired roller hearth type continuous heat treatment furnace, wherein the steel material is a steel pipe.

本発明により、炉内温度分布の均一化が図られ、被熱処理材が均一に加熱されることから、長大な処理時間を要することなく、被熱処理材の全部位に渡って所望の材質を確保することが可能となる。   According to the present invention, the temperature distribution in the furnace is made uniform, and the heat-treated material is heated uniformly, so that a desired material can be secured over all parts of the heat-treated material without requiring a long processing time. It becomes possible to do.

本発明の実施の形態を図１〜図５を用いて説明する。   An embodiment of the present invention will be described with reference to FIGS.

図１に、本発明によるローラーハース式連続熱処理炉のうち、被熱処理材が厚鋼板である場合の一例を示す。該熱処理炉１は、被熱処理材である厚鋼板Ｓの搬送方向に、搬送ロールＲを間に挟んで複数の上部燃焼制御帯２１、２２、２３、２４および下部燃焼制御帯３１、３２、３３、３４に分割されている。厚鋼板Ｓは搬送ロールＲによって炉内への装入、炉内での移動、炉外への抽出がなされる。   FIG. 1 shows an example of a case where a material to be heat treated is a thick steel plate in a roller hearth type continuous heat treatment furnace according to the present invention. The heat treatment furnace 1 includes a plurality of upper combustion control zones 21, 22, 23, 24 and lower combustion control zones 31, 32, 33 with a conveyance roll R interposed therebetween in the conveyance direction of the thick steel plate S that is a material to be heat treated. , 34. The thick steel plate S is loaded into the furnace, moved inside the furnace, and extracted outside the furnace by the transport roll R.

各燃焼制御帯にはその側壁に直火式のバーナ４が複数配置されている。装入側の燃焼制御帯（例えば燃焼制御帯２１、２２、３１、３２）は被熱処理材を常温から略熱処理温度に加熱する機能を持ち、抽出側の燃焼制御帯（例えば燃焼制御帯２３、２４、３３、３４）は被熱処理材を略熱処理温度に保定する機能を持つ。バーナの容量は熱処理能力とともにこのような燃焼制御帯ごとの機能を考慮して決定される。燃焼ガスは炉内に複数設置された排気口から排出され、煙道６を通り、煙突７より大気に排出される。   Each combustion control zone is provided with a plurality of direct-fire burners 4 on its side walls. The combustion control zone on the charging side (for example, the combustion control zone 21, 22, 31, 32) has a function of heating the material to be heat treated from room temperature to a substantially heat treatment temperature, and the combustion control zone on the extraction side (for example, the combustion control zone 23, 24, 33, and 34) have a function of keeping the material to be heat treated at a substantially heat treatment temperature. The capacity of the burner is determined in consideration of the function for each combustion control zone as well as the heat treatment capacity. The combustion gas is discharged from a plurality of exhaust ports installed in the furnace, passes through the flue 6 and is discharged from the chimney 7 to the atmosphere.

熱処理に先立ち、各燃焼制御帯は制御炉温計５の指示値に基づいて目標とする熱処理温度または目標とする加熱曲線に応じた炉温に設定される。設定が完了した後に、被熱処理材を順次炉内へと装入し、常温から略熱処理温度近傍まで加熱する。その際、必要に応じて設定炉温を変更してもよい。   Prior to heat treatment, each combustion control zone is set to a target heat treatment temperature or a furnace temperature corresponding to a target heating curve based on the indicated value of the control furnace thermometer 5. After the setting is completed, the materials to be heat treated are sequentially charged into the furnace and heated from room temperature to near the heat treatment temperature. At that time, the set furnace temperature may be changed as necessary.

被熱処理材は、熱処理温度近傍まで加熱された後に目標熱処理温度に一定時間保定され炉外に抽出される。その間、被熱処理材は搬送ロールＲにより順次抽出側に移動させられる。また、処理時間の管理は、材料温度の測定値または伝熱モデルによる温度計算値またはあらかじめ材料条件（熱処理温度や材料寸法）ごとに定められた操業標準によってなされる。   The material to be heat treated is heated to near the heat treatment temperature, then held at the target heat treatment temperature for a certain time, and extracted outside the furnace. Meanwhile, the heat-treated material is sequentially moved to the extraction side by the transport roll R. Further, the management of the processing time is performed based on a measured value of the material temperature, a temperature calculation value based on a heat transfer model, or an operation standard determined in advance for each material condition (heat treatment temperature and material dimensions).

各燃焼制御帯では制御炉温計５の指示値に基づいて各燃焼制御帯ごとにバーナ４を制御する。燃焼負荷が高い状態（たとえば、被熱処理材が装入された直後や処理温度が高い場合）では全バーナが燃焼する。燃焼負荷が低い状態（例えば、被熱処理材が目標熱処理温度に近づいた状態や処理温度が低い場合）では、その燃焼負荷度合いにより、燃料流量を減じるターンダウン燃焼状態や一部のバーナを消火する間引き燃焼状態に制御される。このとき燃焼空気流量も対応させて減じてもよいし、燃焼空気流量は略一定量に保持してもよい。前者の方法は効率面で利点があり、後者の方法は炉内温度分布形状の変化が小さいという品質面での利点がある。   In each combustion control zone, the burner 4 is controlled for each combustion control zone based on the indicated value of the control furnace thermometer 5. In a state where the combustion load is high (for example, immediately after the material to be heat-treated is charged or when the processing temperature is high), all the burners are burned. When the combustion load is low (for example, when the heat-treated material is close to the target heat treatment temperature or when the treatment temperature is low), the turndown combustion state in which the fuel flow rate is reduced or some burners are extinguished depending on the degree of the combustion load. It is controlled to the thinning combustion state. At this time, the combustion air flow rate may be reduced correspondingly, or the combustion air flow rate may be maintained at a substantially constant amount. The former method has an advantage in terms of efficiency, and the latter method has an advantage in terms of quality that a change in the temperature distribution shape in the furnace is small.

さらに負荷が低下した場合は、一部のバーナを消火して間引き燃焼状態にする。このとき、消火されたバーナからは燃焼空気だけが供給される。加熱効率面では燃焼空気も合わせて遮断することが望ましいが、一般に間引き燃焼状態に制御される燃焼制御帯の燃料消費量は少なく、燃焼空気を遮断することによる省エネルギー効果が設備上の短所に比べて小さいことから、このような構成になることが多い。   If the load further decreases, some of the burners are extinguished to a thinning combustion state. At this time, only the combustion air is supplied from the burned-out burner. In terms of heating efficiency, it is desirable to shut off the combustion air as well, but generally the fuel consumption of the combustion control zone controlled to the thinned-out combustion state is small, and the energy saving effect by shutting off the combustion air is less than the disadvantages of the equipment This is often the case because it is small.

設備上の短所とは、大規模な連続熱処理炉ではバーナが１００本以上配置されることが一般的で、これらすべてに遮断弁を設けることは設備費の増大を招くことと設備の保守管理の煩雑さを招くことである。さらに、燃焼空気を完全に遮断すると熱影響によりバーナ部品の損傷の恐れがあるため、これを回避するためにさらに複雑な機構を具備する必要があることも設備費の増大と設備保守管理の煩雑さを増大させる。   Disadvantages on equipment are that, generally, a large-scale continuous heat treatment furnace has 100 or more burners, and providing all of them with a shut-off valve causes an increase in equipment costs and maintenance of equipment. It causes inconvenience. In addition, if the combustion air is completely shut off, the burner parts may be damaged due to thermal effects. To avoid this, it is necessary to provide a more complicated mechanism. Increase

本発明の実施の形態では、搬送ロールを間に挟んでその上側の帯域を上部燃焼制御帯、下側の帯域を下部燃焼制御帯と区分し、それぞれの帯域において次のようにバーナを配置している。   In the embodiment of the present invention, the upper zone is divided into the upper combustion control zone and the lower zone is divided into the lower combustion control zone with the transport roll in between, and a burner is arranged in each zone as follows. ing.

本発明の第一の形態では、被熱処理材を常温から略目標熱処理温度に加熱する燃焼制御帯のうちの上部と下部の両方の燃焼制御帯と、略目標熱処理温度に保定する燃焼制御帯のうちの下部燃焼制御帯には、図２（ａ）に示すような吐出流速が相対的に低速なバーナを配し、略目標熱処理温度に保定する燃焼制御帯のうちの上部燃焼制御帯には、図２（ｂ）に示すような吐出流速が相対的に高速なバーナを配している。   In the first embodiment of the present invention, both the upper and lower combustion control zones of the combustion control zone that heats the material to be heat treated from room temperature to the substantially target heat treatment temperature, and the combustion control zone that is held at the substantially target heat treatment temperature. The lower combustion control zone is provided with a burner having a relatively low discharge flow rate as shown in FIG. 2 (a), and the upper combustion control zone of the combustion control zone that is maintained at a substantially target heat treatment temperature is provided in the lower combustion control zone. A burner having a relatively high discharge flow rate as shown in FIG.

本発明の第二の形態では、被熱処理材を常温から略目標熱処理温度に加熱する燃焼制御帯には、図２（ａ）に示すような吐出流速が相対的に低速なバーナを配し、略目標熱処理温度に保定する燃焼制御帯には、図２（ｂ）に示すような吐出流速が相対的に高速なバーナを配している。   In the second embodiment of the present invention, a burner having a relatively low discharge flow rate as shown in FIG. 2 (a) is disposed in the combustion control zone for heating the heat-treated material from room temperature to a substantially target heat treatment temperature, A burner having a relatively high discharge flow rate as shown in FIG. 2B is disposed in the combustion control zone that is maintained at a substantially target heat treatment temperature.

本発明の第三の形態では、下部燃焼制御帯には図２（ａ）に示すような吐出流速が相対的に低速なバーナを配し、上部燃焼制御帯には図２（ｂ）に示すような吐出流速が相対的に高速なバーナを配している。   In the third embodiment of the present invention, the lower combustion control zone is provided with a burner having a relatively low discharge flow rate as shown in FIG. 2A, and the upper combustion control zone is shown in FIG. 2B. A burner having a relatively high discharge flow rate is arranged.

本発明の第四の形態では、被熱処理材を常温から略目標熱処理温度に加熱する燃焼制御帯のうち下部燃焼制御帯には、図２（ａ）に示すような吐出流速が相対的に低速なバーナを配し、略目標熱処理温度に保定する燃焼制御帯のうち上部燃焼制御帯と、略目標熱処理温度に保定する燃焼制御帯のうちの上部と下部の両方の燃焼制御帯には、図２（ｂ）に示すような吐出流速が相対的に高速なバーナを配している。   In the fourth embodiment of the present invention, the discharge flow rate as shown in FIG. 2 (a) is relatively low in the lower combustion control zone among the combustion control zones in which the heat-treated material is heated from room temperature to a substantially target heat treatment temperature. The upper combustion control zone of the combustion control zone maintained at the substantially target heat treatment temperature and the upper and lower combustion control zones of the combustion control zone held at the substantially target heat treatment temperature are shown in FIG. A burner having a relatively high discharge flow rate as shown in FIG.

本発明は上述のように、燃焼制御帯の機能および上下帯の別に好適な吐出速度を持つバーナを配することで炉内温度分布を良好にすることが特徴である。以下にそれぞれの燃焼制御帯での吐出流速の違いによる作用を説明する。   As described above, the present invention is characterized in that the furnace temperature distribution is improved by providing a burner having a discharge rate suitable for the function of the combustion control zone and the upper and lower zones. Below, the effect | action by the difference in the discharge flow velocity in each combustion control zone is demonstrated.

高速で吐出するバーナは低速で吐出するバーナに比べて最高温度点がバーナから遠い位置になる。また、連続熱処理炉では両側壁にそれぞれバーナを配するので、特段の配慮をせずにバーナを配置すると、図３に示すような炉幅中央部の温度が高い温度分布形状となる。そのため、炉幅中央部に配置された被熱処理材または被熱処理材の幅中央部位の温度が、炉幅端部に配置された熱処理材または被熱処理材の幅端部位の温度よりも高くなり、被熱処理材に温度偏差が生じる。   A burner that discharges at a high speed has a maximum temperature point farther from the burner than a burner that discharges at a low speed. Further, since the burners are arranged on both side walls in the continuous heat treatment furnace, if the burners are arranged without special consideration, a temperature distribution shape with a high temperature at the center of the furnace width as shown in FIG. 3 is obtained. Therefore, the temperature of the heat-treated material disposed in the furnace width center portion or the width center portion of the heat-treated material becomes higher than the temperature of the heat treatment material disposed in the furnace width end portion or the width end portion of the heat-treated material, A temperature deviation occurs in the material to be heat treated.

このような温度偏差を避けるためには、より炉幅端部側の温度が高まりやすいバーナを配する必要があり、そのためには吐出流速が低速なバーナを配することが好適である。すなわち、間引き燃焼状態に制御されていなければ、吐出流速が低速なバーナを配した方が、吐出流速が高速で吐出するバーナを配した場合よりも、均一な温度分布を得ることができる。   In order to avoid such a temperature deviation, it is necessary to arrange a burner whose temperature at the furnace width end side is likely to increase. For that purpose, it is preferable to arrange a burner having a low discharge flow rate. In other words, if the burn-out combustion state is not controlled, a more uniform temperature distribution can be obtained by arranging a burner having a low discharge flow rate than by arranging a burner that discharges at a high discharge flow rate.

しかし、本発明に用いられる形態の熱処理炉では温度調節を行うためにバーナが間引き燃焼状態に制御されることが多い。バーナが間引き燃焼状態に制御される場合では、点火しているバーナと燃焼空気だけが供給されるバーナとが混在する。燃焼空気だけが供給されるバーナの近傍は周囲と比べて著しく温度が低くなるため、これに起因して被熱処理材に温度偏差が生じる。このような温度偏差を低減するためには高温部と低温部の混合を促進する必要があり、そのためには炉内ガスの攪拌力が高い吐出流速が高速なバーナを配することが好適である。   However, in the heat treatment furnace of the form used in the present invention, the burner is often controlled to a thinning combustion state in order to adjust the temperature. In the case where the burner is controlled to the thinned-out combustion state, an ignited burner and a burner to which only combustion air is supplied are mixed. In the vicinity of the burner to which only the combustion air is supplied, the temperature is remarkably lower than the surroundings, and this causes a temperature deviation in the heat-treated material. In order to reduce such temperature deviation, it is necessary to promote mixing of the high-temperature part and the low-temperature part. For this purpose, it is preferable to arrange a burner having a high stirring speed of the gas in the furnace and a high discharge flow rate. .

一方、各燃焼制御帯の動作状態を考えると以下のようである。被熱処理材を常温から略目標熱処理温度に加熱することが主な機能となる前段の燃焼制御帯では高い燃焼負荷で動作することが多いため間引き燃焼状態に制御されにくい。したがって、吐出流速が低速なバーナを配して炉幅方向温度分布を均一にすることができる。反対に略目標熱処理温度に保定することが主な機能となる後段の燃焼制御帯では頻繁に間引き状態になるため吐出流速が高速なバーナを配して炉幅方向温度分布を均一にすることができる。   On the other hand, the operation state of each combustion control zone is considered as follows. In the preceding stage combustion control zone where the main function is to heat the material to be heat-treated from room temperature to a substantially target heat treatment temperature, it is often operated at a high combustion load, so that it is difficult to control the thinned-out combustion state. Therefore, it is possible to make the temperature distribution in the furnace width direction uniform by arranging a burner having a low discharge flow rate. On the other hand, in the combustion control zone at the later stage where the main function is to maintain the temperature approximately at the target heat treatment temperature, the burnout is frequently thinned out, so a burner with a high discharge flow rate is arranged to make the temperature distribution in the furnace width direction uniform. it can.

また、被熱処理材を常温から略目標熱処理温度に加熱することが主な機能となる燃焼制御帯において、被熱処理材の昇温に高い均一性が求められる場合には、被熱処理材の昇温状況に応じて目標熱処理温度に向かって徐々に設定炉温を高める操業が必要となる。その場合には、バーナは低い燃焼負荷で動作することが多いため間引き燃焼状態に制御されやすい。したがって、そのような操業が大半を占める熱処理炉においては、被熱処理材を常温から略目標熱処理温度に加熱することが主な機能となる燃焼制御帯に吐出流速が高速なバーナを配して炉幅方向温度分布を均一にすることができる。   Also, in the combustion control zone where the main function is to heat the heat-treated material from room temperature to approximately the target heat-treatment temperature, if high uniformity is required for the temperature rise of the heat-treated material, Depending on the situation, it is necessary to gradually increase the set furnace temperature toward the target heat treatment temperature. In that case, since the burner often operates at a low combustion load, it is easily controlled to the thinned-out combustion state. Therefore, in a heat treatment furnace where the majority of such operations are performed, a furnace with a high discharge flow rate burner disposed in a combustion control zone whose main function is to heat the material to be heat treated from room temperature to a substantially target heat treatment temperature. The temperature distribution in the width direction can be made uniform.

ここで、搬送ロールの下側に位置する下部燃焼制御帯について詳細に考察してみると、下部燃焼制御帯では被熱処理材のほかに搬送ロールの温度を維持するための熱量を供給する必要があるため、上部燃焼制御帯に比べて燃焼負荷が高くなるのが普通である。そのため上部燃焼制御帯に比べて下部燃焼制御帯は間引き燃焼状態になりにくい。したがって、そのような場合には下部燃焼制御帯では吐出流速が低速なバーナを配することによって、炉幅方向温度分布を均一にすることができる。   Here, when considering in detail the lower combustion control zone located on the lower side of the transport roll, it is necessary to supply the heat amount for maintaining the temperature of the transport roll in addition to the heat-treated material in the lower combustion control zone. Therefore, the combustion load is usually higher than that in the upper combustion control zone. Therefore, the lower combustion control zone is less likely to be in the thinned-out combustion state than the upper combustion control zone. Therefore, in such a case, the temperature distribution in the furnace width direction can be made uniform by arranging a burner having a low discharge flow rate in the lower combustion control zone.

連続熱処理炉を、図４（ａ）のように、区切った場合、それぞれの帯域に配置するバーナの種類を、上述の作用による炉幅方向温度分布の均一化実現手段を熱処理条件の観点から整理すると、図４（ｂ）のようになる。すなわち、略熱処理目標温度に設定された炉内に被熱処理材を装入する熱処理条件では第一の形態が好適である。ただし、熱処理温度が低く下部燃焼制御帯においても保定時に間引き燃焼状態になりやすい熱処理条件では第二の形態が好適である。また、被熱処理材の昇温に高い均一性が求められる熱処理条件では第三の形態が好適であり、さらに熱処理温度が低い場合には第四の形態が好適となる。したがって、設計者は主たる熱処理条件を勘案して好適な形態を適宜選択することができる。   When the continuous heat treatment furnace is divided as shown in FIG. 4A, the types of burners to be arranged in the respective zones are arranged from the viewpoint of heat treatment conditions by means for realizing the uniform temperature distribution in the furnace width direction by the above-described action. Then, it becomes like FIG.4 (b). That is, the first mode is suitable for the heat treatment conditions in which the material to be heat treated is charged into a furnace set to a substantially heat treatment target temperature. However, the second mode is suitable under the heat treatment conditions where the heat treatment temperature is low and the thin combustion state is likely to occur during holding even in the lower combustion control zone. In addition, the third mode is suitable for heat treatment conditions that require high uniformity in raising the temperature of the material to be heat treated, and the fourth mode is preferred when the heat treatment temperature is low. Therefore, the designer can appropriately select a suitable form in consideration of the main heat treatment conditions.

ここで用いる吐出流速が相対的に低速なバーナと高速なバーナとは、例えば図２に示すような吐出口径が異なるバーナによって実現することができる。このようなバーナを配することで上述の炉幅方向温度分布の均一化を図る直火型ローラーハース式連続熱処理炉が本発明の第五の形態である。   The burner having a relatively low discharge flow rate and the high-speed burner used here can be realized by, for example, burners having different discharge port diameters as shown in FIG. The direct-fired roller hearth type continuous heat treatment furnace which makes the above-mentioned furnace width direction temperature distribution uniform by arranging such a burner is the fifth embodiment of the present invention.

図２に示すものは熱処理炉で広く用いられる高速燃焼型のバーナである。バーナ８には燃料口９から供給された燃料と燃焼空気口１０から供給された燃焼空気とが燃焼室１１で急激に混合して火炎が形成される。この燃焼室１１の開口部の面積を調整することにより吐出流速を変化させることができる。吐出流速が相対的に低速なバーナの吐出口径ＤLは、吐出流速が相対的に高速なバーナの吐出口径ＤHよりも大きい。すなわち、ＤH／ＤL＜１である。 FIG. 2 shows a high-speed combustion type burner widely used in a heat treatment furnace. In the burner 8, the fuel supplied from the fuel port 9 and the combustion air supplied from the combustion air port 10 are rapidly mixed in the combustion chamber 11 to form a flame. The discharge flow rate can be changed by adjusting the area of the opening of the combustion chamber 11. The discharge port diameter D L of the burner having a relatively low discharge flow rate is larger than the discharge port diameter D H of the burner having a relatively high discharge flow rate. That is, D H / D L <1.

この吐出口径比ＤH／ＤLが１に近い値であれば、全てのバーナの吐出流速が略同一ということになり、上述の作用によって炉幅方向温度分布を均一にできない燃焼制御帯が生じる。 If this discharge port diameter ratio D H / D L is a value close to 1, the discharge flow rates of all the burners are substantially the same, and a combustion control zone in which the temperature distribution in the furnace width direction cannot be made uniform is generated by the above-described action. .

発明者らは、吐出口径比と炉内幅方向温度分布との関係を種々調査をした結果、間引き燃焼状態が頻繁に発生する燃焼制御帯の炉幅方向温度分布に関して図５に示すような結果を得た。すなわち全ての燃焼制御帯で炉幅方向温度分布を均一にする効果を得るためには、（ＤH／ＤL）2≦０．７の範囲とすることが望ましいことを見出した。また、より好ましくは（ＤH／ＤL）2≦０．５であることを見出した。この範囲では吐出流速が相対的に低速なバーナの吐出流速は、吐出流速が相対的に高速なバーナの吐出流速に比べて半分以下となり、炉内ガス流れおよび温度分布形成にとって有意な違いとなっている。 As a result of various investigations on the relationship between the discharge port diameter ratio and the temperature distribution in the furnace width direction, the inventors have obtained the results shown in FIG. 5 regarding the temperature distribution in the furnace width direction of the combustion control zone in which the thinned combustion state frequently occurs. Got. That is, it has been found that in order to obtain the effect of uniforming the temperature distribution in the furnace width direction in all combustion control zones, it is desirable to set the range of (D H / D L ) 2 ≦ 0.7. It was also found that (D H / D L ) 2 ≦ 0.5 is more preferable. In this range, the discharge flow rate of the burner with a relatively low discharge flow rate is less than half the discharge flow rate of the burner with a relatively high discharge flow rate, which is a significant difference for the furnace gas flow and temperature distribution formation. ing.

このほかにもバーナの燃焼容量を変えることで吐出流速を変更することができるが、バーナの燃焼容量は熱処理能力や熱処理条件から決定されるべきものであり、望ましくない。   In addition to this, the discharge flow rate can be changed by changing the combustion capacity of the burner, but the combustion capacity of the burner should be determined from the heat treatment capacity and heat treatment conditions, and is not desirable.

以上が燃焼制御帯ごとに好適なバーナを配することによる炉内温度分布均一化の作用の説明である。従来技術では燃焼制御帯の機能および作動状態の特性に応じて好適なバーナを効果的に配する技術はなかったが、発明者は熱処理炉内の温度分布を詳細に調査した結果、上述したような作用を見出し本発明に至った。   The above is description of the effect | action of uniform temperature distribution in a furnace by arrange | positioning a suitable burner for every combustion control zone. In the prior art, there was no technique for effectively arranging a suitable burner according to the function of the combustion control zone and the characteristics of the operating state. However, as a result of detailed investigation of the temperature distribution in the heat treatment furnace, the inventor as described above. As a result, the present invention has been found.

なお、図１、４では燃焼制御帯が上下各４帯の場合を示しているが、本発明はこれに限られるものではない。また、図１では排ガス煙道が上部燃焼制御帯ごとに１本設置されているが、本発明はこれに限られるものではなく、複数の上部燃焼制御帯に対して１本の煙道を設定してもよく、また、煙道を下部燃焼制御帯に設置してもよい。また、図１では排ガス煙道を集合させてから煙突より排気している場合を示しているが、本発明はこれに限られるものではなく、個別の煙道ごとに直接煙突を設けてもよいし、一部の煙道だけを集合させてから煙突を設けてもよい。   Although FIGS. 1 and 4 show the case where the combustion control zones are four zones on the upper and lower sides, the present invention is not limited to this. Further, in FIG. 1, one exhaust flue is installed for each upper combustion control zone, but the present invention is not limited to this, and one flue is set for a plurality of upper combustion control zones. Alternatively, the flue may be installed in the lower combustion control zone. Further, FIG. 1 shows a case where exhaust gas flues are gathered and then exhausted from the chimney. However, the present invention is not limited to this, and a direct chimney may be provided for each individual flue. However, the chimney may be provided after only a part of the flue is gathered.

以上、被熱処理材が厚鋼板の場合を例に説明したが、本発明はこれに限られるものではなく、鋼管など異種形状の鋼材でもよく、また、他の金属であってもよい。   As described above, the case where the heat-treated material is a thick steel plate has been described as an example. However, the present invention is not limited to this, and may be a steel material having a different shape such as a steel pipe, or may be another metal.

上記に説明した本発明によれば、直火型ローラーハース式連続熱処理炉の炉内温度分布の均一性を向上させることができるため、被熱処理材の加熱温度を均一にでき、被熱処理材を適正な処理時間で所望の材質を得ることができるとともに、処理時間適正な処理時間で処理が完了することから省エネルギーも同時に達成できる。   According to the present invention described above, since the uniformity of the temperature distribution in the direct-fired roller hearth type continuous heat treatment furnace can be improved, the heating temperature of the heat treated material can be made uniform, A desired material can be obtained in an appropriate processing time, and energy saving can be achieved at the same time because the processing is completed in an appropriate processing time.

［実施例１］
以下に、厚鋼板の焼戻し処理を対象とした本発明の実施例と従来技術による例を説明し、本発明の効果を説明する。 [Example 1]
Below, the Example of this invention and the example by a prior art which made object the tempering process of a thick steel plate are demonstrated, and the effect of this invention is demonstrated.

図１に示すローラーハース式の連続熱処理炉に被熱処理材となる厚鋼板を順次装入して焼戻し処理をした。連続熱処理炉は炉長５０ｍで炉幅が５ｍで高さが２ｍである。連続熱処理炉は装入側から上下各４つの燃焼制御帯に分割されており、装入側の上下各２つの燃焼制御帯には２３０ｋＷの燃焼バーナを、抽出側の上下各２つの燃焼制御帯には１１５ｋＷの燃焼バーナをそれぞれ配した。燃料にはコークス炉ガスを用いた。燃焼空気はブロアより常温で各バーナに供給した。被熱処理材は長さ１０ｍ、幅３．５ｍ、厚み５０ｍｍの普通鋼厚鋼板である。   Thick steel plates to be heat treated were sequentially charged into the roller hearth type continuous heat treatment furnace shown in FIG. 1 and tempered. The continuous heat treatment furnace has a furnace length of 50 m, a furnace width of 5 m, and a height of 2 m. The continuous heat treatment furnace is divided into four upper and lower combustion control zones from the charging side, with 230 kW combustion burners in the upper and lower two combustion control zones on the charging side, and two upper and lower combustion control zones on the extraction side. Each was equipped with a 115 kW combustion burner. Coke oven gas was used as the fuel. Combustion air was supplied from a blower to each burner at room temperature. The material to be heat-treated is a plain steel thick steel plate having a length of 10 m, a width of 3.5 m, and a thickness of 50 mm.

６００℃での焼戻し処理を実施するために、被熱処理材の装入に先立ってすべての燃焼制御帯の炉温を６００℃に設定した。炉温は各燃焼制御帯の炉幅中央部かつ燃焼制御帯長さの略中央部に設置された制御炉温計で測定した。熱処理は目標値（本実施例では６００℃）±１０℃の状態を２０分間保定して完了するものとした。加熱温度を確認するために、被熱処理材には図６に●印で示す部位Ｔに熱電対を埋設して厚鋼板の均一性を評価した。   In order to carry out the tempering process at 600 ° C., the furnace temperature of all combustion control zones was set to 600 ° C. prior to the charging of the heat-treated material. The furnace temperature was measured with a controlled furnace thermometer installed at the center of the furnace width of each combustion control zone and at the approximate center of the length of the combustion control zone. The heat treatment was completed by maintaining the target value (600 ° C. in this example) ± 10 ° C. for 20 minutes. In order to confirm the heating temperature, a thermocouple was embedded in a portion T indicated by a black circle in FIG. 6 to evaluate the uniformity of the thick steel plate.

本発明の実施例として、図２（ａ）に示す吐出流速が相対的に低速のバーナを燃焼制御帯２１、２２、３１、３２、３３、３４に配し、図２（ｂ）に示す吐出流速が相対的に高速なバーナを燃焼制御帯２３、２４に配した。吐出口径比ＤH／ＤL＝略０．７とし、両バーナの吐出流速比は略２となっている。 As an embodiment of the present invention, a burner having a relatively low discharge flow rate shown in FIG. 2A is arranged in the combustion control zones 21, 22, 31, 32, 33, and 34, and the discharge shown in FIG. A burner having a relatively high flow rate was disposed in the combustion control zones 23 and 24. The discharge port diameter ratio D H / D L = approximately 0.7, and the discharge flow rate ratio of both burners is approximately 2.

従来技術の比較例として、すべての燃焼制御帯に図２（ｂ）に示す吐出流速が相対的に高速なバーナを配した。従来技術の比較例として吐出流速が相対的に高速なバーナを配した理由は次の理由による。すなわち、熱処理においては被熱処理材の温度均一性が極めて重要であるが、処理の最終段階では燃焼負荷が著しく低下して間引き燃焼状態に制御されるため、この状態での温度均一性を重要視して、間引き制御状態での均一性が良好な吐出流速が相対的に高速なバーナを炉全体にわたって配した。   As a comparative example of the prior art, burners having a relatively high discharge flow rate shown in FIG. 2B are arranged in all combustion control zones. The reason why a burner having a relatively high discharge flow rate is provided as a comparative example of the prior art is as follows. In other words, in heat treatment, the temperature uniformity of the material to be heat treated is extremely important, but in the final stage of the treatment, the combustion load is remarkably reduced and the thinned-out combustion state is controlled, so the temperature uniformity in this state is regarded as important. Then, a burner having a relatively high discharge flow rate with good uniformity in the thinning-out control state was arranged over the entire furnace.

本発明による実施例および従来技術による比較例における、厚鋼板各部位の温度履歴を図７（ａ）、（ｂ）に示す。本発明による実施例（ａ）では、最初の測定点が５９０℃（目標熱処理温度−１０℃）に到達するまでに７８分を要し、最後の測定点が５９０℃に到達するまでに８８分を要した。その後の２０分の温度保定を経て、１０８分で熱処理が完了する結果となった。一方で、従来技術による比較例（ｂ）では、最初の測定点が５９０℃に到達するまでに７８分を要し、最後の測定点が５９０℃に到達するまでに１２４分を要した。２０分の温度保定時間と合わせて１４４分の処理時間が必要となった。   7A and 7B show the temperature history of each part of the thick steel plate in the example according to the present invention and the comparative example according to the prior art. In Example (a) according to the present invention, it takes 78 minutes for the first measurement point to reach 590 ° C. (target heat treatment temperature—10 ° C.), and 88 minutes for the last measurement point to reach 590 ° C. Cost. After 20 minutes of temperature holding, the heat treatment was completed in 108 minutes. On the other hand, in comparative example (b) according to the prior art, it took 78 minutes for the first measurement point to reach 590 ° C., and 124 minutes for the last measurement point to reach 590 ° C. A processing time of 144 minutes was required together with a temperature holding time of 20 minutes.

いずれの場合においても所望の材質を得ることができたが、本発明の実施例では処理時間で２５％の処理時間短縮が図れている。本発明の実施例では部位の違いによる温度差が小さいために、すべての部位で速やかに加熱が進行したが、従来技術の比較例では加熱速度に大きな差が生じたため狙い熱処理温度に到達するまでに長大な時間を要した。   In any case, a desired material could be obtained, but in the embodiment of the present invention, the processing time was reduced by 25%. In the examples of the present invention, since the temperature difference due to the difference in the parts was small, the heating proceeded quickly in all the parts, but in the comparative example of the prior art, a large difference occurred in the heating rate, so that the target heat treatment temperature was reached. It took a long time.

［実施例２］
吐出流速が相対的に低速なバーナと相対的に高速なバーナによる炉内温度分布の違いを確認するために、前記実施例１のバーナ配置とは別に燃焼制御帯２３、２４にも吐出流速が相対的に低速なバーナを配して、被熱処理材を常温から略目標熱処理温度に加熱することを主たる機能とする燃焼制御帯と略目標熱処理温度に保定することを主たる機能とする燃焼制御帯の別ごとに、および、上部燃焼制御帯と下部燃焼制御帯の別ごとに、それぞれ吐出流速が相対的に低速なバーナと相対的に高速なバーナによる炉内温度分布の違いを調査した。その際の熱処理材条件は実施例１の場合と同じである。 [Example 2]
In order to confirm the difference in temperature distribution in the furnace between the burner having a relatively low discharge flow rate and the burner having a relatively high discharge flow rate, the discharge control flow rate is also applied to the combustion control zones 23 and 24 in addition to the burner arrangement of the first embodiment. Combustion control zone with the main function of heating the material to be heat treated from room temperature to the approximate target heat treatment temperature and the combustion control zone with the main function of maintaining the target heat treatment temperature at a relatively low temperature by arranging a relatively low-speed burner The difference in the furnace temperature distribution between the burner with a relatively low discharge flow rate and the burner with a relatively high speed was investigated for each of the above and for each of the upper combustion control zone and the lower combustion control zone. The heat treatment material conditions at that time are the same as those in Example 1.

各燃焼制御帯に吐出流速が相対的に低速なバーナを設置した場合と相対的に高速なバーナを設置した場合の炉内温度分布の比較結果を図８に示す。炉内温度分布均一性を熱処理材が設置されている範囲の炉幅方向の温度偏差で評価すると以下のようになった。   FIG. 8 shows a comparison result of the temperature distribution in the furnace when a burner having a relatively low discharge flow rate is installed in each combustion control zone and when a relatively high speed burner is installed. The temperature distribution uniformity in the furnace was evaluated by the temperature deviation in the furnace width direction in the range where the heat treatment material was installed, and the following was obtained.

被熱処理材を常温から目標熱処理温度に加熱することを主たる機能とする上部燃焼制御帯の結果を図８（ａ）に示す。吐出流速が相対的に低速なバーナの方が均一な温度分布となっている。この燃焼制御帯ではほとんど間引き燃焼状態にはならなかった。   FIG. 8A shows the result of the upper combustion control zone whose main function is to heat the material to be heat-treated from the normal temperature to the target heat treatment temperature. The burner having a relatively low discharge flow rate has a more uniform temperature distribution. In this combustion control zone, there was almost no thinning combustion state.

被熱処理材を常温から略目標熱処理温度に加熱することを主たる機能とする下部燃焼制御帯の結果を図８（ｂ）に示す。吐出流速が相対的に低速なバーナの方が均一な温度分布となっている。この燃焼制御帯ではほとんど間引き燃焼状態にはならなかった。   FIG. 8B shows the result of the lower combustion control zone whose main function is to heat the material to be heat-treated from room temperature to a substantially target heat treatment temperature. The burner having a relatively low discharge flow rate has a more uniform temperature distribution. In this combustion control zone, there was almost no thinning combustion state.

被熱処理材を略目標熱処理温度に保定することを主たる機能とする上部燃焼制御帯の結果を図８（ｃ）に示す。吐出流速が相対的に高速なバーナの方が均一な温度分布となっている。この燃焼制御帯では頻繁に間引き燃焼状態となった。   FIG. 8C shows the result of the upper combustion control zone whose main function is to keep the material to be heat-treated at a substantially target heat treatment temperature. A burner having a relatively high discharge flow rate has a more uniform temperature distribution. In this combustion control zone, a thinning combustion state frequently occurred.

被熱処理材を略目標熱処理温度に保定することを主たる機能とする下部燃焼制御帯の結果を図８（ｄ）に示す。吐出流速が相対的に低速なバーナの方が均一な温度分布となっている。この燃焼制御帯ではほとんど間引き燃焼状態にはならなかった。   FIG. 8D shows the result of the lower combustion control zone whose main function is to keep the material to be heat-treated at substantially the target heat treatment temperature. The burner having a relatively low discharge flow rate has a more uniform temperature distribution. In this combustion control zone, there was almost no thinning combustion state.

これらの結果は前述した本発明の作用によって実施例１の結果が得られていることを示すものであり、燃焼制御帯ごとに好適なバーナを配するという本発明の効果を実証するものである。   These results show that the result of Example 1 is obtained by the operation of the present invention described above, and demonstrate the effect of the present invention that a suitable burner is provided for each combustion control zone. .

本発明の連続熱処理炉の一形態を示す図である。It is a figure which shows one form of the continuous heat processing furnace of this invention. 本発明の連続熱処理炉に配置したバーナを説明する図である。It is a figure explaining the burner arrange | positioned in the continuous heat processing furnace of this invention. 炉幅方向の炉内温度分布の一例を説明する図である。It is a figure explaining an example of the furnace temperature distribution of the furnace width direction. 熱処理条件別の好適なバーナ配置を説明する図である。It is a figure explaining suitable burner arrangement according to heat treatment conditions. 吐出口径の違いによる炉内温度分布の違いを説明する図である。It is a figure explaining the difference in the temperature distribution in a furnace by the difference in a discharge port diameter. 実施例における厚鋼板の温度測定箇所を説明する図である。It is a figure explaining the temperature measurement location of the thick steel plate in an Example. 実施例における厚鋼板の加熱履歴を説明する図であり、（ａ）は本発明による実施例であり、（ｂ）は従来技術による比較例を示す。It is a figure explaining the heating history of the thick steel plate in an Example, (a) is an Example by this invention, (b) shows the comparative example by a prior art. 吐出流速が相対的に低速なバーナと吐出流速が相対的に高速なバーナによる炉幅方向の炉内温度分布の違いを説明する図である。It is a figure explaining the difference in the furnace temperature distribution of the furnace width direction by the burner with a relatively low discharge flow rate, and the burner with a relatively high discharge flow rate.

符号の説明Explanation of symbols

１ 直火型ローラーハース式連続熱処理炉
２１、２２、２３、２４ 上部燃焼制御帯
３１、３２、３３、３４ 下部燃焼制御帯
４ 直火型バーナ
５ 制御炉温計
６ 煙道
７ 煙突
８ バーナ
９ バーナの燃料供給口
１０ バーナの燃焼空気供給口
１１ バーナの燃焼室
ＤH 吐出流速が相対的に高速なバーナの吐出口径
ＤL 吐出流速が相対的に低速なバーナの吐出口径
Ｒ 搬送ロール
Ｓ 厚鋼板
Ｔ 厚鋼板の温度測定点 DESCRIPTION OF SYMBOLS 1 Direct-fire type roller hearth type continuous heat treatment furnace 21, 22, 23, 24 Upper combustion control zone 31, 32, 33, 34 Lower combustion control zone 4 Direct-fire type burner 5 Control furnace thermometer 6 Chimney 7 Chimney 8 Burner 9 Burner fuel supply port 10 Burner combustion air supply port 11 Burner combustion chamber DH Discharge port diameter with relatively high discharge flow rate D L Discharge port diameter with relatively low discharge flow rate R Transport roll S Thickness Steel plate T Temperature measurement point of thick steel plate

Claims (8)

燃焼制御機能として間引き燃焼機能を有する直火型のローラーハース式連続熱処理炉であって、炉内空間が被熱処理材の搬送方向に複数の燃焼制御帯に分割された熱処理炉において、被熱処理材を処理温度近くまで加熱する前段の燃焼制御帯のうち搬送ロールの上側と下側の両方の燃焼制御帯および被熱処理材温度を略処理温度に保定する後段の燃焼制御帯のうち搬送ロールの下側の燃焼制御帯には、吐出流速が相対的に低速なバーナを配し、前記後段の燃焼制御帯のうち搬送ロールの上側の燃焼制御帯には、吐出流速が相対的に高速なバーナを配したことを特徴とする直火型ローラーハース式連続熱処理炉。   A direct-fired roller hearth type continuous heat treatment furnace having a thinning-out combustion function as a combustion control function, wherein the furnace space is divided into a plurality of combustion control zones in the conveyance direction of the material to be heat treated. Of the previous stage combustion control zone that heats the material to near the processing temperature, both the upper and lower side combustion control zones of the transport roll, and the lower stage of the combustion control zone that keeps the temperature of the heat-treated material substantially at the processing temperature. The combustion control zone on the side is provided with a burner having a relatively low discharge flow rate, and the burner having a relatively high discharge flow rate is provided on the combustion control zone on the upper side of the transport roll in the combustion control zone in the subsequent stage. A direct-fired roller hearth-type continuous heat treatment furnace characterized in that it is arranged. 燃焼制御機能として間引き燃焼機能を有する直火型のローラーハース式連続熱処理炉であって、炉内空間が被熱処理材の搬送方向に複数の燃焼制御帯に分割された熱処理炉において、被熱処理材を処理温度近くまで加熱する前段の燃焼制御帯のうち搬送ロールの上側と下側の両方の燃焼制御帯には、吐出流速が相対的に低速なバーナを配し、被熱処理材温度を略処理温度に保定する後段の燃焼制御帯のうち搬送ロールの上側と下側の両方の燃焼制御帯には、吐出流速が相対的に高速なバーナを配したことを特徴とする直火型ローラーハース式連続熱処理炉。   A direct-fired roller hearth type continuous heat treatment furnace having a thinning-out combustion function as a combustion control function, wherein the furnace space is divided into a plurality of combustion control zones in the conveyance direction of the material to be heat treated. Among the combustion control zones of the previous stage that heats the steel to near the processing temperature, burner with a relatively low discharge flow rate is arranged in both the upper and lower combustion control zones of the transport roll, so that the temperature of the heat-treated material is substantially processed Direct-fired roller hearth type, characterized in that a burner with a relatively high discharge flow rate is placed in both the upper and lower combustion control zones of the transport roll among the subsequent combustion control zones that hold the temperature. Continuous heat treatment furnace. 燃焼制御機能として間引き燃焼機能を有する直火型のローラーハース式連続熱処理炉であって、炉内空間が被熱処理材の搬送方向に複数の燃焼制御帯に分割された熱処理炉において、搬送ロールの下側の燃焼制御帯には吐出流速が相対的に低速なバーナを配し、搬送ロールの上側の燃焼制御帯には吐出流速が相対的に高速なバーナを配したことを特徴とする直火型ローラーハース式連続熱処理炉。   A direct-fired roller hearth type continuous heat treatment furnace having a thinning-out combustion function as a combustion control function, wherein the furnace space is divided into a plurality of combustion control zones in the conveyance direction of the material to be heat treated. A direct fire characterized in that a burner with a relatively low discharge flow rate is arranged in the lower combustion control zone, and a burner with a relatively high discharge flow rate is arranged in the combustion control zone on the upper side of the transport roll. Type roller hearth type continuous heat treatment furnace. 燃焼制御機能として間引き燃焼機能を有する直火型のローラーハース式連続熱処理炉であって、炉内空間が被熱処理材の搬送方向に複数の燃焼制御帯に分割された熱処理炉において、被熱処理材を処理温度近くまで加熱する前段の燃焼制御帯のうち搬送ロールの下側の燃焼制御帯には、吐出流速が相対的に低速なバーナを配し、被熱処理材温度を略処理温度に保定する後段の燃焼制御帯のうち搬送ロールの上側と下側の両方の燃焼制御帯および前記前段の燃焼制御帯のうち搬送ロールの上側の燃焼制御帯には、吐出流速が相対的に高速なバーナを配したことを特徴とする直火型ローラーハース式連続熱処理炉。   A direct-fired roller hearth type continuous heat treatment furnace having a thinning-out combustion function as a combustion control function, wherein the furnace space is divided into a plurality of combustion control zones in the conveyance direction of the material to be heat treated. A burner with a relatively low discharge flow rate is placed in the combustion control zone below the transport roll in the previous stage combustion control zone that heats the steel to near the processing temperature, and the temperature of the heat-treated material is maintained at the processing temperature. A burner having a relatively high discharge flow rate is provided in both the upper and lower combustion control zones of the transport roll in the subsequent combustion control zone and the combustion control zone on the upper side of the transport roll in the preceding combustion control zone. A direct-fired roller hearth-type continuous heat treatment furnace characterized in that it is arranged. 前記吐出流速が相対的に高速なバーナの吐出口径を、前記吐出流速が相対的に低速なバーナの吐出口径よりも小さくすることを特徴とする請求項１〜４のいずれか１項に記載の直火型ローラーハース式連続熱処理炉。   5. The discharge port diameter of a burner having a relatively high discharge flow rate is made smaller than the discharge port diameter of a burner having a relatively low discharge flow rate. 6. Direct fire type roller hearth type continuous heat treatment furnace. 前記被熱処理材が鋼材であることを特徴とする請求項１〜５のいずれか１項に記載の直火型ローラーハース式連続熱処理炉。   The direct heat type roller hearth type continuous heat treatment furnace according to any one of claims 1 to 5, wherein the material to be heat treated is a steel material. 前記鋼材が厚鋼板であることを特徴とする請求項６記載の直火型ローラーハース式連続熱処理炉。   The direct-fired roller hearth type continuous heat treatment furnace according to claim 6, wherein the steel material is a thick steel plate. 前記鋼材が鋼管であることを特徴とする請求項６記載の直火型ローラーハース式連続熱処理炉。   The direct-fired roller hearth type continuous heat treatment furnace according to claim 6, wherein the steel material is a steel pipe.
JP2007335165A 2007-12-26 2007-12-26 Direct-fired type roller hearth continuous heat treatment furnace Expired - Fee Related JP4987689B2 (en)

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