JPH06281119A - Radiant tube and its manufacture thereof - Google Patents
Radiant tube and its manufacture thereofInfo
- Publication number
- JPH06281119A JPH06281119A JP5068788A JP6878893A JPH06281119A JP H06281119 A JPH06281119 A JP H06281119A JP 5068788 A JP5068788 A JP 5068788A JP 6878893 A JP6878893 A JP 6878893A JP H06281119 A JPH06281119 A JP H06281119A
- Authority
- JP
- Japan
- Prior art keywords
- radiant tube
- range
- thickness
- alloy
- radiant
- 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.)
- Withdrawn
Links
Landscapes
- Gas Burners (AREA)
- Combustion Of Fluid Fuel (AREA)
- Coating By Spraying Or Casting (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明はラジアントチューブ及び
その製造方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiant tube and a method for manufacturing the same.
【０００２】[0002]
【従来の技術】熱処理炉、例えば鋼板あるいは鋼管の熱
処理炉で、鋼板あるいは鋼管を還元ガス雰囲気中で加熱
するために、図５に示すように炉内に耐熱鋼製のラジア
ントチューブＲが配設されており、このラジアントチュ
ーブ内でバーナー７による加熱を行い、自身が赤熱して
鋼板や鋼管を加熱する。図中５は直管部、６は曲管部で
ある。このためラジアントチューブの内面側は燃焼火炎
（１３００℃）または排ガス（８００〜１１００℃）に
直接的に曝される。2. Description of the Related Art In a heat treatment furnace, for example, a heat treatment furnace for steel plates or steel pipes, a radiant tube R made of heat resistant steel is provided in the furnace for heating the steel plates or steel pipes in a reducing gas atmosphere, as shown in FIG. In this radiant tube, heating is performed by the burner 7 so that the radiant tube itself becomes red and heats the steel plate or the steel tube. In the figure, 5 is a straight pipe part, and 6 is a curved pipe part. Therefore, the inner surface side of the radiant tube is directly exposed to combustion flame (1300 ° C) or exhaust gas (800 to 1100 ° C).
【０００３】燃焼火炎または排ガスは理論空気比にて完
全燃焼するか、または空気比が１以下の条件で燃焼させ
る場合は無酸化または還元性の性状となり酸化の問題は
ない。しかし実際は省エネルギーの観点から、未燃焼ガ
スを発生させないために空気比を１以上にして燃焼させ
る場合が多く、燃焼火炎または排ガス中に酸素が存在す
る。例えば空気比を１．２としてバーナー燃焼させ、燃
焼に液化天然ガスを使用している場合は排ガス中の酸素
濃度が３．５〜４．５％となり、この酸素が高温度域で
ラジアントチューブ内面の酸化を促進する。このためラ
ジアントチューブは酸化に対して耐用性のあるステンレ
ス系の耐熱鋳鋼品（ＪＩＳ−Ｇ５１２２）のＳＣＨ１５
及びＳＣＨ２２並びにＳＣＨ２４が広く用いられてい
た。Combustion flame or exhaust gas is completely combusted at the theoretical air ratio, or when it is combusted under the condition that the air ratio is 1 or less, it becomes non-oxidizing or reducing property and there is no problem of oxidation. However, in actuality, from the viewpoint of energy saving, in many cases combustion is performed with an air ratio of 1 or more in order to prevent generation of unburned gas, and oxygen is present in the combustion flame or exhaust gas. For example, when liquefied natural gas is used for combustion with burner combustion with an air ratio of 1.2, the oxygen concentration in the exhaust gas is 3.5 to 4.5%, and this oxygen is inside the radiant tube in the high temperature range. Promotes the oxidation of. Therefore, the radiant tube is a SCH15 stainless steel heat-resistant cast steel product (JIS-G5122) that is resistant to oxidation.
And SCH22 and SCH24 were widely used.
【０００４】ステンレス系の耐熱鋳鋼品は高温度の酸化
雰囲気下で使用される過程で、その表面に極薄い酸化物
の保護皮膜を形成して、その後の酸化反応を抑制する。
しかしステンレス系の耐熱鋳鋼品中に自然に形成された
Ｃｒ2 Ｏ3 の保護皮膜は厚みが数オングストロームの極
薄い皮膜であるため、長期間使用すると蒸発等により消
滅する。実際のステンレス系耐熱鋳鋼品のラジアントチ
ューブ内面では以上に述べた保護皮膜形成と消滅が繰返
し起こっており、この過程でチューブ厚みが経時的に減
少する。Stainless steel heat-resistant cast steel products, in the process of being used in an oxidizing atmosphere at high temperature, form a very thin protective film of oxide on the surface thereof to suppress the subsequent oxidation reaction.
However, the protective film of Cr 2 O 3 naturally formed in the stainless steel heat-resistant cast steel is an extremely thin film having a thickness of several angstroms, and therefore disappears due to evaporation or the like when used for a long period of time. On the inner surface of the radiant tube of the actual heat-resistant cast stainless steel product, the protective film formation and disappearance described above repeatedly occur, and the tube thickness decreases with time in this process.
【０００５】[0005]
【発明が解決しようとする課題】ステンレス系の耐熱鋳
鋼品は鋳造性に優れるほか、ラジアントチューブ固有の
曲管部の成形も容易にでき、安価で高温強度と熱衝撃性
に優れ、高温酸化域でもある程度の耐酸化性を有するた
め広く用いられているが、例えば鋼板熱処理炉で使用し
た場合の寿命は４年程度で、炉内に１００〜２０本のラ
ジアントチューブを配設して使用している場合は、単一
のライン設備で年間２５〜５０本もの更新が必要であ
り、整備コストの増加と取替えに必要な設備休止による
生産の機械損失等により極めて大きな損失となってい
た。In addition to excellent castability, stainless steel heat-resistant cast steel products can be easily formed into curved pipe parts unique to radiant tubes, are inexpensive, have excellent high-temperature strength and thermal shock resistance, and have high-temperature oxidation regions. However, it is widely used because it has a certain degree of oxidation resistance. For example, when used in a steel plate heat treatment furnace, the life is about 4 years, and 100 to 20 radiant tubes are arranged in the furnace and used. In the case of a single line facility, it is necessary to renew 25 to 50 lines a year, which results in an extremely large loss due to an increase in maintenance costs and a mechanical loss in production due to facility shutdown required for replacement.
【０００６】ラジアントチューブを更新する理由は亀裂
の発生と酸化減耗による穴あきである。亀裂の発生がス
テンレス系の耐熱鋳鋼品を高温雰囲気下で長時間使用し
た場合の脆化が原因の場合は鋼の化学組成の改善によっ
てある程度抑制できる。あるいは亀裂の発生が自身の熱
応力による場合は、実公平３−３５９２４号公報のよう
にチューブに熱応力を吸収するための伸縮管を取付ける
ことによってある程度抑制できるが、高温酸化の場合、
その抑制が非常に難しい。The reason for renewing the radiant tube is the occurrence of cracks and perforation due to oxidative wear. When the occurrence of cracks is caused by embrittlement when a stainless steel heat-resistant cast steel product is used in a high temperature atmosphere for a long time, it can be suppressed to some extent by improving the chemical composition of the steel. Alternatively, if the generation of cracks is due to its own thermal stress, it can be suppressed to some extent by attaching a telescopic tube for absorbing thermal stress to the tube as in Japanese Utility Model Publication No. 3-35924, but in the case of high temperature oxidation,
The control is very difficult.
【０００７】またＣｏまたはＷあるいはＮｂ等の高融点
金属を多用して耐酸化性を高める方法もあるが、これら
の金属は高価なためラジアントチューブの製造コストが
極めて高いものになり、コストに見合う効果が見込めな
い。そこで本発明はこれらの高価な金属を用いることな
く、耐酸化性を高めたラジアントチューブ及びその製造
方法を提供するものである。There is also a method of increasing the oxidation resistance by using a high melting point metal such as Co, W or Nb, but since these metals are expensive, the manufacturing cost of the radiant tube becomes extremely high and it is worth the cost. The effect cannot be expected. Therefore, the present invention provides a radiant tube having improved oxidation resistance and a method for producing the same, without using these expensive metals.
【０００８】[0008]
【課題を解決するための手段】本発明の要旨は以下のと
おりである。 （１）高温の還元ガス雰囲気中で使用するラジアントチ
ューブの内面（内面側の表面）に、１０〜２５０μｍの
皮膜厚みの合金溶射層を形成したことを特徴とするラジ
アントチューブ。 （２）前記（１）項記載のラジアントチューブの燃焼排
ガスが通過するチューブの長さ方向において、バーナー
側から全長の３分の２の長さの範囲あるいは範囲内の限
定部分の内面に、ＣｏまたはＮｉあるいはＣｏ及びＮｉ
を主成分とする合金の溶射皮膜を形成したことを特徴と
するラジアントチューブ。 （３）前記（２）項のラジアントチューブの長さ方向に
おいて、バーナー側から全長の３分の２の長さの範囲あ
るいは範囲内の限定部分の内面にＣｏまたはＮｉあるい
はＣｏ及びＮｉを主成分とするが、さらに１５〜３０％
のＣｒ及び５〜１２％のＡｌ並びに０．２〜０．７％の
ＹあるいはＨｆを加えた化学組成とした合金の溶射皮膜
を形成したことを特徴とするラジアントチューブ。The gist of the present invention is as follows. (1) A radiant tube characterized in that an alloy sprayed layer having a coating thickness of 10 to 250 μm is formed on the inner surface (inner surface side) of the radiant tube used in a high-temperature reducing gas atmosphere. (2) In the length direction of the tube through which the combustion exhaust gas of the radiant tube according to the above item (1) passes, a range of a length of two-thirds of the total length from the burner side or a limited portion within the range is coated with Co. Or Ni or Co and Ni
A radiant tube having a sprayed coating of an alloy containing as a main component. (3) In the length direction of the radiant tube of the above item (2), Co or Ni or Co and Ni are main components on the inner surface of the range of the length of two-thirds from the burner side or the limited part within the range. However, 15-30%
2. A radiant tube characterized in that a sprayed coating of an alloy having a chemical composition containing Cr and 5-12% Al and 0.2-0.7% Y or Hf is formed.
【０００９】（４）前記（１）項記載のラジアントチュ
ーブを製造するにあたり、ラジアントチューブを直管部
と曲管部の複数の部分に分けて鋳造した後、前記（３）
項記載の内面溶射を組立て前に実施し、溶接組立て時に
溶接接合部の材質をＣｒ及びＮｉを主成分とする合金で
Ｃｒの化学組成を２５〜３５％としたことを特徴とする
ラジアントチューブの製造方法。 （５）前記（４）項記載のラジアントチューブを製造す
るにあたり、ラジアントチューブの直管部と曲管部の複
数の部分の溶接接合部の厚みが接合部の周囲厚みの最大
１．５倍になるような溶接ビードの厚みとしたことを特
徴とするラジアントチューブの製造方法。(4) In manufacturing the radiant tube according to the item (1), the radiant tube is divided into a straight pipe portion and a plurality of curved pipe portions and cast, and then the (3).
Of the radiant tube, wherein the inner surface thermal spraying according to the item is carried out before assembling, and the material of the welded joint at the time of welding and assembly is an alloy containing Cr and Ni as main components and the chemical composition of Cr is 25 to 35%. Production method. (5) In manufacturing the radiant tube according to the item (4), the thickness of the welded joint between the straight tube portion and the curved tube portion of the radiant tube is 1.5 times at most the peripheral thickness of the joint portion. A method of manufacturing a radiant tube, characterized in that the thickness of the weld bead is set as follows.
【００１０】[0010]
【作用】図１に示すように高温の還元ガス雰囲気中で使
用するステンレス系の耐熱鋳鋼２製のラジアントチュー
ブＲの内面に、高温度での酸化反応が極めて緩慢な合金
の溶射皮膜１を形成させるのは３．５〜４．５％の酸素
を含む排ガスからステンレス系の耐熱鋳鋼の界面を保護
するためである。As shown in FIG. 1, on the inner surface of a radiant tube R made of stainless heat-resistant cast steel 2 used in a high-temperature reducing gas atmosphere, a thermal spray coating 1 of an alloy whose oxidation reaction at a high temperature is extremely slow is formed. The purpose is to protect the interface of the stainless heat-resistant cast steel from the exhaust gas containing 3.5 to 4.5% oxygen.
【００１１】皮膜厚みを１０〜２５０μｍとするのは、
下限が１０μｍ未満では溶射皮膜が不均一で耐熱鋳鋼の
界面が局部的に露出する場合があり均等に被覆できない
ためである。上限を２５０μｍとするのは、この値を超
えると溶射皮膜の残留応力が局部的に８０kg／mm2 以上
の値となり溶射皮膜の層の間に微細なクラックが発生す
る。この現象は溶射皮膜形成後のカラーチェック法と呼
ばれる探傷法で確認できる。The film thickness of 10 to 250 μm is
This is because if the lower limit is less than 10 μm, the thermal spray coating may not be uniform and the interface of the heat-resistant cast steel may be locally exposed, so that the coating cannot be performed uniformly. When the upper limit is set to 250 μm, if the value exceeds this value, the residual stress of the thermal spray coating locally becomes a value of 80 kg / mm 2 or more, and fine cracks are generated between the layers of the thermal spray coating. This phenomenon can be confirmed by a flaw detection method called a color check method after forming the sprayed coating.
【００１２】微細なクラックが発生すると、排ガスがク
ラックを通して浸透するため、チューブの耐熱鋳鋼を保
護するための皮膜の遮蔽機能が著しく損なわれる。また
浸透した排ガスは耐熱鋳鋼を酸化させるため、酸化時の
体積膨張により耐熱鋳鋼と溶射皮膜間が僅かに剥離す
る。ラジアントチューブで炉内温度を一定に制御するた
め、バーナーの点火と消火を繰り返している場合やトラ
ブルで炉を休止する場合の急速降温時の熱応力により、
前述の母材酸化による溶射皮膜の剥離がさらに進展、皮
膜に決定的なダメージを与えることになる。When fine cracks are generated, the exhaust gas penetrates through the cracks, so that the shielding function of the coating for protecting the heat-resistant cast steel of the tube is significantly impaired. Further, the permeated exhaust gas oxidizes the heat-resistant cast steel, and therefore the heat-resistant cast steel and the sprayed coating are slightly separated due to volume expansion during oxidation. Since the temperature inside the furnace is controlled to be constant by the radiant tube, due to the thermal stress during rapid cooling when the burner is ignited and extinguished repeatedly or when the furnace is stopped due to trouble,
The peeling of the thermal spray coating due to the above-mentioned base material oxidation further progresses, and the coating is decisively damaged.
【００１３】ラジアントチューブＲの長さ方向におい
て、バーナー７側から全長の３分の２の長さの範囲内
（図３の３に示す）の内面に溶射皮膜を形成するのは、
図４のＡ，Ｂ，Ｃ，Ｄ，Ｅで示すように、ラジアントチ
ューブＲ内の温度は排ガスがチューブを通過して行く過
程で鋼板に抜熱され、全長の３分の２の長さの付近で排
ガスの温度が耐熱鋳鋼にても長期使用可能な８００℃以
下になるため、合金溶射を実施しても経済的な効果が小
さいためである。In the longitudinal direction of the radiant tube R, the thermal spray coating is formed on the inner surface within the range of two-thirds of the total length from the burner 7 side (indicated by 3 in FIG. 3).
As shown by A, B, C, D, and E in FIG. 4, the temperature in the radiant tube R is removed by the steel plate in the process of the exhaust gas passing through the tube, and the temperature of the two-thirds of the total length is This is because the temperature of the exhaust gas becomes 800 ° C. or lower which can be used for a long time even in heat-resistant cast steel in the vicinity, so that the economical effect is small even if alloy spraying is performed.
【００１４】ＣｏあるいはＮｉを主成分とする合金の溶
射皮膜を形成するには、この組成の皮膜の高温強度が優
れ、熱膨張率がステンレス系の耐熱鋳鋼品と近いため、
前述の熱応力による剥離や亀裂が発生しないためであ
る。またＣｏあるいはＮｉを主成分とする合金は融点が
１７００℃以下と低いため、気孔率が低い点も有利な点
である。In order to form a sprayed coating of an alloy containing Co or Ni as a main component, the coating of this composition has excellent high-temperature strength, and its coefficient of thermal expansion is close to that of a stainless steel heat-resistant cast steel product.
This is because the above-mentioned peeling or cracking due to thermal stress does not occur. Further, since the alloy containing Co or Ni as the main component has a low melting point of 1700 ° C. or lower, it is also advantageous that the porosity is low.
【００１５】Ａｌを加えるのは適量のＡｌがラジアント
チューブで燃焼した酸素を含む排ガスとの接触によっ
て、溶射皮膜の界面に図２に示すようなＡｌ2 Ｏ3 の保
護皮膜４を自己形成するためである。皮膜の酸化の反応
速度を左右する重要な指標として拡散係数が広く用いら
れるが、Ａｌ2 Ｏ3 は酸素イオンの拡散係数が温度条件
１６００℃以下の酸素圧力１５２Torrの雰囲気下におい
て、６．３×１０-8cm2ｓ-1で耐熱鋳鋼の界面に排ガス
の酸化雰囲気下で自己形成するＣｒ2 Ｏ3 の同一条件の
拡散係数１５．９cm2 ｓ-1より、格段に小さいため酸化
反応速度が極めて遅い。よって酸化に対する抵抗力を増
すためにＡｌ添加によるＡｌ2 Ｏ3 の薄膜を自己形成さ
せることが極めて効果的である。Al is added so that a suitable amount of Al self-forms a protective coating 4 of Al 2 O 3 as shown in FIG. 2 at the interface of the spray coating by contact with exhaust gas containing oxygen burned in a radiant tube. Is. Although the diffusion coefficient is widely used as an important index that influences the reaction rate of the oxidation of the film, Al 2 O 3 has a diffusion coefficient of oxygen ions of 6.3 × in an atmosphere of a temperature condition of 1600 ° C. or less and an oxygen pressure of 152 Torr. than 10 -8 cm 2 s -1 diffusion coefficient 15.9 cm 2 s -1 for the same conditions of Cr 2 O 3 to self-forming in an oxidizing atmosphere of the exhaust gas at the interface of the heat-resistant cast steel, the is much smaller for the oxidation reaction rate Extremely slow. Therefore, it is extremely effective to self-form a thin film of Al 2 O 3 by adding Al in order to increase resistance to oxidation.
【００１６】Ａｌの化学組成を５〜１２％とするのは、
５％未満ではＡｌ2 Ｏ3 の皮膜形成が十分でないためで
あり、１２％超では皮膜の延性が損なわれ前述の熱応力
による部分的な剥離や亀裂が発生するためである。さら
に１５〜３０％のＣｒを加えるのは、ＣｒがＡｌ2 Ｏ3
の形成を促進させるためであるが、１５％未満ではＡｌ
の化学組成に左右されるが、Ａｌの組成を５〜１２％に
した場合は、Ａｌ2 Ｏ3 の形成が不完全になり、保護皮
膜としての効果が損なわれる。また化学組成が３０％超
とするとＡｌの場合と同様に、皮膜の延性が損なわれ熱
応力による部分的な剥離や亀裂が発生するためである。The chemical composition of Al is 5 to 12%,
This is because if it is less than 5%, the film formation of Al 2 O 3 is not sufficient, and if it exceeds 12%, the ductility of the film is impaired and the above-mentioned thermal stress causes partial peeling or cracking. Further, 15 to 30% of Cr is added because Cr is Al 2 O 3
Is to accelerate the formation of Al, but if it is less than 15%, Al
However, if the Al composition is 5 to 12%, the formation of Al 2 O 3 will be incomplete and the effect as a protective film will be impaired. Also, if the chemical composition exceeds 30%, the ductility of the coating is impaired and partial peeling or cracking due to thermal stress occurs, as in the case of Al.
【００１７】また０．２〜０．７％のＹまたはＨｆを加
えるのは、皮膜の密着性の向上を目的としたもので、
０．２％未満では密着性を高める顕著な効果が得られな
い一方、０．７％超とするとＹまたはＨｆが溶射皮膜中
の粒界に濃化するため皮膜強度を低下させる。The addition of 0.2 to 0.7% Y or Hf is for the purpose of improving the adhesion of the film.
If it is less than 0.2%, a remarkable effect of enhancing the adhesiveness cannot be obtained, whereas if it exceeds 0.7%, Y or Hf is concentrated at the grain boundaries in the thermal spray coating, so that the coating strength is lowered.
【００１８】ラジアントチューブを直管部と曲管部の複
数の部分に分けて鋳造した後、内面溶射を組立て前に実
施し、溶接組立て時に溶接接合部の材質をＣｒ及びＮｉ
を主成分とする合金でＣｒの化学組成を２５〜３５％と
するのは、複雑な形状のラジアントチューブでは溶接接
合部の溶射が組立て後にできないため、非常に限定され
てはいるが、溶接ビード部が排ガスに曝され、ビードに
沿って局部的に酸化減耗するためで、ビード部分だけ限
定的にＣｒの化学組成を高め、耐酸化性を向上させるた
めである。After the radiant tube is divided into a straight pipe portion and a plurality of curved pipe portions and cast, the inner surface is sprayed before assembling, and the material of the welded joint portion is Cr and Ni at the time of welding and assembling.
Although the chemical composition of Cr in the alloy containing Cr as the main component is 25 to 35%, it is very limited in the complicated shape of the radiant tube because the spraying of the welded joint cannot be performed after assembling. This is because the part is exposed to exhaust gas and is locally oxidized and depleted along the bead, so that the chemical composition of Cr is increased only in the bead part and the oxidation resistance is improved.
【００１９】Ｃｒが２５％未満ではビード保護のために
表層に自己形成されるＣｒ2 Ｏ3 の厚みが薄く耐酸化性
が不十分である。３５％超では高温下で多量のＣｒ炭化
物を生成してビード部分が脆化するため、熱応力や自重
による応力によって亀裂が発生する。また、ラジアント
チューブの直管部と曲管部の複数の部分の溶接部の厚み
を接合部の周囲厚みの最大１．５倍になるような溶接ビ
ードの厚みとするのは、Ｃｒの化学組成を２５〜３５％
として耐酸化性を高めているが、さらに溶接部の厚みを
増して減耗代を確保したもので、最大１．５倍としたの
は１．５倍超では溶接時の残留応力により溶接熱影響部
に亀裂が発生するのを防止するためである。When Cr is less than 25%, the thickness of Cr 2 O 3 self-formed on the surface layer for bead protection is small and the oxidation resistance is insufficient. If it exceeds 35%, a large amount of Cr carbide is generated at high temperature to embrittle the bead portion, and thus cracks are generated due to thermal stress or stress due to its own weight. Further, the thickness of the weld bead so that the thickness of the welded portions of the straight pipe portion and the curved pipe portion of the radiant tube is up to 1.5 times the peripheral thickness of the joint portion is the chemical composition of Cr. 25-35%
As a result, the oxidation resistance is increased, but the thickness of the welded portion is further increased to secure the wear reduction allowance. A maximum of 1.5 times is the effect of welding heat due to residual stress during welding when it exceeds 1.5 times. This is to prevent the occurrence of cracks in the part.
【００２０】[0020]
〔実施例１〕既に成形済みの曲管と直管を組合わせた形
状の複雑なＷ型のステンレス系の耐熱鋳鋼品ＳＣＨ２４
（ＪＩＳ−Ｇ５１２２の２５％Ｃｒ、２０％Ｎｉ）のラ
ジアントチューブの長さ方向において、バーナー側から
全長の３分の２の長さの範囲内の内面に、１００μｍの
Ｃｏ及びＮｉを主成分とする合金の溶射皮膜をプラズマ
溶射法にて皮膜を形成させたもので、２０％のＣｒ及び
７％のＡｌ並びに０．５％のＹを加えた化学組成とした
合金の溶射皮膜を形成した。[Example 1] SCH24, a heat-resistant cast steel product of complex W-shaped stainless steel having a complex shape of a bent pipe and a straight pipe that have already been formed
In the length direction of the radiant tube of (JIS-G5122 25% Cr, 20% Ni), 100 μm of Co and Ni are the main components on the inner surface within the range of two-thirds of the total length from the burner side. The thermal sprayed coating of the above alloy was formed by a plasma thermal spraying method, and the thermal sprayed coating of an alloy having a chemical composition containing 20% Cr, 7% Al and 0.5% Y was formed.
【００２１】このＷ型の内面溶射ラジアントチューブを
燃焼空気比が１．２、燃料に液化天然ガスを使用して、
ガス中の酸素濃度が実測で４．０％の冷延鋼板の連続焼
鈍ラインの加熱炉にて使用した結果、従来のステンレス
系の耐熱鋳鋼品ＳＣＨ２２（ＪＩＳ−Ｇ５１２２の２５
％Ｃｒ、２０％Ｎｉ）のバーナー近傍の最も温度の高い
場所での内表面の酸化減肉量が０．３mm／年であったの
が、本発明品の場合は前述と同じバーナー近傍の最も温
度の高い場所で酸化減肉量が０．１３mm／年であった。
ラジアントチューブの寿命も従来の４年から８年に延び
た。寿命が２倍延びたことによって価格がＳＣＨ２２の
１．２倍としても、ラジアントチューブの整備コストは
従来の６０％に削減することができた。This W-type inner surface sprayed radiant tube has a combustion air ratio of 1.2 and uses liquefied natural gas as fuel.
As a result of using it in a heating furnace of a continuous annealing line for cold-rolled steel sheets in which the oxygen concentration in the gas is actually 4.0%, the conventional stainless steel heat-resistant cast steel product SCH22 (JIS-G5122 25
% Cr, 20% Ni), the amount of oxidative thinning on the inner surface was 0.3 mm / year at the highest temperature near the burner. The amount of oxidation thinning was 0.13 mm / year at a high temperature.
The life of the radiant tube has been extended from 4 years to 8 years. Even if the price is 1.2 times that of the SCH22 due to the doubled life, the maintenance cost of the radiant tube could be reduced to 60% of the conventional one.
【００２２】〔実施例２〕実施例１のＷ型のラジアント
チューブの溶接部の材質をＣｒ及びＮｉを主成分とする
合金においてＣｒの化学組成を３０％とし、さらに溶接
接合部の厚みが周囲厚みの１．５倍になるような溶接ビ
ードとした内面溶射ラジアントチューブを燃焼空気比が
１．２、燃料に液化天然ガスを使用して、ガス中の酸素
濃度が実測で４．０％の冷延鋼板の連続焼鈍ラインの加
熱炉にて使用した結果、バーナー近傍の最も温度の高い
場所での内表面の溶射部分の酸化減耗量が０．１３mm／
年で、実施例１と同じであったが、溶接部の酸化減耗量
が減少し、かつ余肉厚が大きいためラジアントチューブ
の寿命が従来の４年から１０年に延びた。寿命が２．５
倍延びた場合、価格がＳＣＨ２２の１．８倍としても、
ラジアントチューブの整備コストは従来の７２％となり
整備コストを大幅に削減することができた。[Embodiment 2] The material of the welded portion of the W-type radiant tube of Embodiment 1 is made of an alloy containing Cr and Ni as main components, and the chemical composition of Cr is 30%. An internal sprayed radiant tube with a weld bead that is 1.5 times the thickness has a combustion air ratio of 1.2, and liquefied natural gas is used as the fuel, and the oxygen concentration in the gas is actually 4.0%. As a result of using it in the heating furnace of the continuous annealing line for cold-rolled steel sheet, the oxidation loss of the sprayed part on the inner surface at the highest temperature near the burner was 0.13 mm /
Although it was the same as that of Example 1 in a year, the life of the radiant tube was extended from the conventional 4 years to 10 years because the oxidative wear amount of the welded portion was reduced and the excess wall thickness was large. Life is 2.5
If it doubles, even if the price is 1.8 times that of SCH22,
The maintenance cost of the radiant tube was 72% of the conventional one, and the maintenance cost could be significantly reduced.
【００２３】[0023]
【発明の効果】本発明によれば、ラジアントチューブの
取替え本数が低減でき、ラジアントチューブ自身の購入
費及び取替え作業費並びに取付け部の煉瓦の修復等の整
備コストを大幅に削減することができた。さらに炉休止
時のラジアントチューブの取替え本数の低減は炉修中の
取替え時間を短縮できるためライン稼働率の向上につな
がり、稼働時間の増加による生産量の増量も可能になっ
た。また縦型の鋼板の連続設備の場合は、ラジアントチ
ューブの取替えは危険作業を伴うが、本発明品の採用に
より、その作業頻度を大幅に削減することができ、作業
負荷の軽減にも寄与した。これらは間接的に製品を放射
伝熱により加熱している加熱炉内に配設されたラジアン
トチューブの全てについて当てはめることができ、その
いずれの場合でも実施例と同等の効果を得ることができ
る。According to the present invention, the number of radiant tubes to be replaced can be reduced, and the purchase costs and replacement work costs of the radiant tubes themselves and the maintenance costs such as the repair of bricks in the mounting portion can be greatly reduced. . Furthermore, reducing the number of radiant tubes that can be replaced when the furnace is idle can shorten the replacement time during furnace repairs, leading to improved line availability, and increased production hours due to increased operating time. Further, in the case of continuous equipment of vertical type steel plate, replacement of the radiant tube involves dangerous work, but by adopting the product of the present invention, the work frequency can be significantly reduced, which also contributed to the reduction of the work load. . These can be applied to all of the radiant tubes arranged in the heating furnace which indirectly heats the product by radiative heat transfer, and in any case, the same effect as the embodiment can be obtained.
【図１】本発明を適用しようとするＷ型ラジアントチュ
ーブの内面に形成させたＣｏ及びＮｉを主成分とする合
金の溶射皮膜の層構成の断面図である。FIG. 1 is a cross-sectional view of a layer structure of a thermal spray coating of an alloy containing Co and Ni as main components formed on the inner surface of a W-type radiant tube to which the present invention is applied.
【図２】本発明を適用しようとするＷ型ラジアントチュ
ーブの内面に被覆したＣｏ及びＮｉを主成分とする合金
の溶射皮膜系の皮膜の表層に形成したＡｌ2 Ｏ3 を示す
ミクロ組織図である。FIG. 2 is a microstructure diagram showing Al 2 O 3 formed on a surface layer of a thermal spray coating of an alloy containing Co and Ni as main components, which is coated on the inner surface of a W type radiant tube to which the present invention is applied. is there.
【図３】Ｃｏ及びＮｉを主成分とする合金の溶射皮膜の
形成範囲の説明図である。FIG. 3 is an explanatory diagram of a formation range of a sprayed coating of an alloy containing Co and Ni as main components.
【図４】燃料に液化天然ガスを使用して、ガス中の酸素
濃度が実測で４．０％の冷延鋼板の連続焼鈍ラインの加
熱炉にて使用した場合のチューブ長さ方向の温度実測値
の説明図である。[Fig. 4] Temperature measurement in the tube length direction when using liquefied natural gas as a fuel and using it in a heating furnace in a continuous annealing line for cold-rolled steel sheets in which the oxygen concentration in the gas is actually 4.0%. It is explanatory drawing of a value.
【図５】本発明を適用しようとするＷ型ラジアントチュ
ーブの設備概要の説明図である。FIG. 5 is an explanatory diagram of the equipment outline of a W-type radiant tube to which the present invention is applied.
１ 合金の溶射皮膜 ２ ステンレス系の耐熱鋳鋼品 ３ 溶射皮膜の形成範囲 ４ 溶射皮膜の界面に形成されたＡｌ2 Ｏ3 皮膜 ５ Ｗ型ラジアントチューブの直管部 ６ Ｗ型ラジアントチューブの曲管部 ７ バーナー1 Thermal spray coating of alloy 2 Stainless steel heat-resistant cast steel product 3 Range of thermal spray coating 4 Al 2 O 3 coating formed at the interface of thermal spray coating 5 Straight pipe section of W type radiant tube 6 Curved section of W type radiant tube 7 burners
Claims (5)
アントチューブの内面に、１０〜２５０μｍの皮膜厚み
の合金の溶射層を形成したことを特徴とするラジアント
チューブ。1. A radiant tube characterized in that a sprayed layer of an alloy having a coating thickness of 10 to 250 μm is formed on the inner surface of the radiant tube used in a high-temperature reducing gas atmosphere.
焼排ガスが通過するチューブの長さ方向において、バー
ナー側から全長の３分の２の長さの範囲あるいは範囲内
の限定部分の内面に、ＣｏまたはＮｉあるいはＣｏ及び
Ｎｉを主成分とする合金の溶射皮膜を形成したことを特
徴とするラジアントチューブ。2. The radiant tube according to claim 1, in the longitudinal direction of the tube through which combustion exhaust gas passes, a range of a length of two-thirds from the burner side or a limited portion within the range is coated with Co. Alternatively, a radiant tube having a sprayed coating of Ni or an alloy containing Co and Ni as a main component is formed.
さ方向において、バーナー側から全長の３分の２の長さ
の範囲あるいは範囲内の限定部分の内面にＣｏまたはＮ
ｉあるいはＣｏ及びＮｉを主成分とするが、さらに１５
〜３０％のＣｒ及び５〜１２％のＡｌ並びに０．２〜
０．７％のＹあるいはＨｆを加えた化学組成とした合金
の溶射皮膜を形成したことを特徴とするラジアントチュ
ーブ。3. In the length direction of the radiant tube according to claim 2, Co or N is formed on the inner surface of a range of a length of two-thirds of the burner side or a limited portion within the range.
i or Co and Ni are the main components, but further 15
-30% Cr and 5-12% Al and 0.2-
A radiant tube having a sprayed coating of an alloy with a chemical composition containing 0.7% of Y or Hf.
造するにあたり、ラジアントチューブを直管部と曲管部
の複数の部分に分けて鋳造した後、請求項３記載の内面
溶射を組立て前に実施し、溶接組立て時に溶接接合部の
材質をＣｒ及びＮｉを主成分とする合金でＣｒの化学組
成を２５〜３５％としたことを特徴とするラジアントチ
ューブの製造方法。4. In manufacturing the radiant tube according to claim 1, after the radiant tube is divided into a plurality of parts of a straight pipe part and a curved pipe part and cast, the inner surface thermal spraying according to claim 3 is carried out before assembling. A method of manufacturing a radiant tube, wherein a material of a welded joint is an alloy containing Cr and Ni as main components and a chemical composition of Cr is 25 to 35% at the time of welding and assembling.
造するにあたり、ラジアントチューブの直管部と曲管部
の複数の部分の溶接接合部の厚みが、接合部の周囲厚み
の最大１．５倍になるような溶接ビードの厚みとしたこ
とを特徴とするラジアントチューブの製造方法。5. In manufacturing the radiant tube according to claim 4, the thickness of the welded joint between the straight pipe portion and the curved pipe portion of the radiant tube is up to 1.5 times the peripheral thickness of the joint portion. A method of manufacturing a radiant tube, characterized in that the thickness of the weld bead is set as follows.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5068788A JPH06281119A (en) | 1993-03-26 | 1993-03-26 | Radiant tube and its manufacture thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5068788A JPH06281119A (en) | 1993-03-26 | 1993-03-26 | Radiant tube and its manufacture thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06281119A true JPH06281119A (en) | 1994-10-07 |
Family
ID=13383818
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5068788A Withdrawn JPH06281119A (en) | 1993-03-26 | 1993-03-26 | Radiant tube and its manufacture thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06281119A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001323361A (en) * | 2000-05-16 | 2001-11-22 | Nisshin Steel Co Ltd | Radiant tube excellent in high temperature oxidation resistance and its production method |
-
1993
- 1993-03-26 JP JP5068788A patent/JPH06281119A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001323361A (en) * | 2000-05-16 | 2001-11-22 | Nisshin Steel Co Ltd | Radiant tube excellent in high temperature oxidation resistance and its production method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 20000530 |