JPH0931576A - Heat transfer tube for sulfuric acid dew point corrosion resistance - Google Patents
Heat transfer tube for sulfuric acid dew point corrosion resistanceInfo
- Publication number
- JPH0931576A JPH0931576A JP20677995A JP20677995A JPH0931576A JP H0931576 A JPH0931576 A JP H0931576A JP 20677995 A JP20677995 A JP 20677995A JP 20677995 A JP20677995 A JP 20677995A JP H0931576 A JPH0931576 A JP H0931576A
- Authority
- JP
- Japan
- Prior art keywords
- heat transfer
- sulfuric acid
- transfer tube
- dew point
- acid dew
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L58/00—Protection of pipes or pipe fittings against corrosion or incrustation
- F16L58/02—Protection of pipes or pipe fittings against corrosion or incrustation by means of internal or external coatings
- F16L58/04—Coatings characterised by the materials used
- F16L58/08—Coatings characterised by the materials used by metal
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、主に重油および石
炭を燃料とするボイラにおける耐硫酸露点腐食用自溶性
合金を適用した伝熱管に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat transfer tube to which a self-fluxing alloy for sulfuric acid dew point corrosion resistance is applied in a boiler mainly using heavy oil and coal.
【０００２】[0002]
【従来の技術】重油及び石炭中には約３０％以下の無機
物質が存在し、これらは燃焼によって分解、蒸発する。
この際、排ガスとしてＳＯ2 ，ＣＯ2 ，ＣＯ，Ｏ2 ，Ｈ
2 Ｏ，ＮＯｘなどが発生するが、このうちＳＯ2 とＨ2
Ｏは１００℃前後の低温において反応して硫酸を形成す
る。この硫酸は腐食性が非常に激しいために、炭素鋼あ
るいはオーステナイト系ステンレス鋼からなる伝熱管を
腐食する。そのため定期的に設備の保全を行い腐食の激
しい伝熱管を取り替えており、多大な時間と経費を要し
ている。2. Description of the Related Art Heavy oil and coal contain about 30% or less of inorganic substances, which are decomposed and evaporated by combustion.
At this time, SO 2 , CO 2 , CO, O 2 and H as exhaust gas
2 O, NOx, etc. are generated, of which SO 2 and H 2
O reacts at a low temperature around 100 ° C. to form sulfuric acid. Since this sulfuric acid is extremely corrosive, it corrodes the heat transfer tubes made of carbon steel or austenitic stainless steel. For this reason, the equipment is regularly maintained and the heat transfer tubes with severe corrosion are replaced, which requires a great deal of time and expense.
【０００３】硫酸露点腐食の防止には、（１）無機系の
ライニング、（２）高Ｓｉ系の材料、アロイ６２５等が
使用あるいは検討されているが、前者の無機系のライニ
ングは長時間使用に際しての耐久性がなく、また後者の
ものは優れた耐食性を有するが高価なため大面積部を有
するボイラなどの伝熱管では材料コストが非常に高く実
用的ではない。In order to prevent sulfuric acid dew point corrosion, (1) an inorganic lining, (2) a high Si material, alloy 625, etc. are used or studied, but the former inorganic lining is used for a long time. However, the latter has excellent corrosion resistance but is expensive, so that a heat transfer tube such as a boiler having a large area has a very high material cost and is not practical.
【０００４】[0004]
【発明が解決しようとする課題】本発明は上記技術水準
に鑑み、組織安定性が良好で優れた耐硫酸露点腐食用伝
熱管を提供しようとするものである。SUMMARY OF THE INVENTION In view of the above-mentioned state of the art, the present invention is to provide a heat transfer tube for sulfuric acid dew point corrosion resistance which is excellent in structure stability and excellent.
【０００５】[0005]
【課題を解決するための手段】本発明はＣｒ：１５〜３
０ｗｔ％、Ｓｉ：８〜１０ｗｔ％、Ｍｏ：３〜１０ｗｔ
％、Ｃｕ：１〜３ｗｔ％、Ｎｉ：残部よりなる自溶性合
金被覆耐硫酸露点腐食用伝熱管である。The present invention provides Cr: 15-3
0 wt%, Si: 8-10 wt%, Mo: 3-10 wt%
%, Cu: 1 to 3 wt%, Ni: balance of self-fluxing alloy coating heat transfer tube for sulfuric acid dew point corrosion resistance.
【０００６】[0006]
【発明の実施の形態】本発明の耐硫酸露点腐食用伝熱管
は、Ｃｒ：１５〜３０ｗｔ％、Ｓｉ：８〜１０ｗｔ％、
Ｍｏ：３〜１０ｗｔ％、Ｃｕ：１〜３ｗｔ％、Ｎｉ：残
部よりなる耐硫酸露点腐食用自溶性合金を溶射法によ
り、通常の伝熱管、例えば炭素鋼あるいはＣｒ、Ｍｏを
含む低合金鋼製伝熱管の表面に少なくとも０．２ｍｍの
厚さに適用し、該溶射皮膜形成後の伝熱管を適用された
自溶性合金が溶融する温度、例えば１１００℃前後の温
度に加熱して該皮膜の封孔処理を行うことによって得ら
れる。BEST MODE FOR CARRYING OUT THE INVENTION The heat transfer tube for sulfuric acid dew point corrosion of the present invention comprises Cr: 15 to 30 wt%, Si: 8 to 10 wt%,
A self-fluxing alloy for sulfuric acid dew point corrosion consisting of Mo: 3 to 10 wt%, Cu: 1 to 3 wt%, and Ni: balance is formed by a conventional heat transfer tube, for example, carbon steel or low alloy steel containing Cr and Mo. A heat transfer tube having a thickness of at least 0.2 mm is applied to the surface of the heat transfer tube, and the heat transfer tube after the formation of the sprayed coating is heated to a temperature at which the applied self-fluxing alloy melts, for example, a temperature of around 1100 ° C. to seal the coating. It is obtained by performing a pore treatment.
【０００７】以下、本発明で使用する自溶性合金の元素
量設定理由を説明する。The reason for setting the element amounts of the self-fluxing alloy used in the present invention will be described below.
【０００８】（１）Ｃｒ： 自溶性合金の酸化被膜を構
成するのに重要な元素であり、最低１５ｗｔ％必要であ
る。しかしながら、３０ｗｔ％を越えて含有されるとσ
相などを形成して脆くなるのでその上限を３０ｗｔ％と
した。(1) Cr: Cr is an important element for forming an oxide film of a self-fluxing alloy, and is required to be at least 15 wt%. However, when the content exceeds 30 wt%, σ
The upper limit was set to 30 wt% because it forms a phase and becomes brittle.
【０００９】（２）Ｓｉ： 自溶性合金の溶射後に、そ
の皮膜に存在する孔を封孔するために、皮膜の一部を溶
融処理するが、Ｓｉはこの溶射皮膜の融点を低下させる
元素として有効であり、１１００℃前後で溶融させるた
めには８〜１０ｗｔ％が必要である。(2) Si: After the thermal spraying of the self-fluxing alloy, a part of the coating is melted in order to seal the pores existing in the coating. Si is an element that lowers the melting point of the thermal sprayed coating. It is effective, and 8 to 10 wt% is necessary for melting at around 1100 ° C.
【００１０】（３）Ｍｏ： 塩化物に対する応力腐食割
れ、孔食を防止するのに重要な元素であり、これらの欠
点を防止するには３ｗｔ％のＭｏが必要であるが、１０
ｗｔ％を越えて含有すると脆くなるので、３〜１０ｗｔ
％とした。(3) Mo: It is an important element for preventing stress corrosion cracking and pitting corrosion with respect to chlorides, and 3 wt% of Mo is necessary to prevent these defects.
If contained in excess of wt%, it becomes brittle, so 3-10 wt
%.
【００１１】（４）Ｃｕ： 硫酸露点腐食を防止するの
に重要な元素であり、それを保持するためには最低１ｗ
ｔ％が必要であるが、含有量が多すぎると金属間化合物
を形成し脆くなるので、その上限を３ｗｔ％とした。(4) Cu: This is an important element for preventing sulfuric acid dew point corrosion, and at least 1 w is required to retain it.
Although t% is necessary, if the content is too large, an intermetallic compound is formed and becomes brittle, so the upper limit was made 3 wt%.
【００１２】（５）Ｎｉ： 組織的に安定なオーステナ
イトを形成するのに重要な元素であり、このために残部
をＮｉとした。(5) Ni: This is an important element for forming a structurally stable austenite, and therefore the balance is Ni.
【００１３】（作用）溶射法によって、Ｃｒ：１５〜３
０ｗｔ％、Ｓｉ：８〜１０ｗｔ％、Ｍｏ：３〜１０ｗｔ
％、Ｃｕ：１〜３ｗｔ％、Ｎｉ：残部よりなる自溶性合
金の溶射材料を用いて形成した溶射皮膜を、１１００℃
前後で加熱することによって得られた自溶性合金皮膜
は、Ｃｒ，Ｍｏ，Ｃｕにより耐食性が保持され、また、
Ｓｉの融点低下の効果により封孔処理が期待でき、さら
にＮｉにより組織が安定化する。これにより腐食環境が
激しい硫酸露点腐食環境中でも本発明の伝熱管は耐食性
が期待できる。(Operation) Cr: 15 to 3 by the thermal spraying method
0 wt%, Si: 8-10 wt%, Mo: 3-10 wt%
%, Cu: 1 to 3 wt%, Ni: 1100 ° C. of a thermal spray coating formed by using a thermal spray material of self-fluxing alloy
The self-fluxing alloy film obtained by heating before and after the corrosion resistance is retained by Cr, Mo and Cu.
Due to the effect of lowering the melting point of Si, sealing treatment can be expected, and Ni stabilizes the structure. Accordingly, the heat transfer tube of the present invention can be expected to have corrosion resistance even in a sulfuric acid dew point corrosive environment where the corrosive environment is severe.
【００１４】[0014]
【実施例】以下、本発明の実施例及び比較例をあげ、本
発明の伝熱管の効果を明らかにする。EXAMPLES The effects of the heat transfer tube of the present invention will be clarified below with reference to Examples and Comparative Examples of the present invention.
【００１５】〇（実施例の構成） プラズマ溶射材料として、表１に示す１６種類の材料を
アトマイズ法により製作した。図１に、表１中のＮＯ．
３のアトマイズ粉の表面形態の光学顕微鏡写真（１００
倍）を代表して示した。(Structure of Example) As the plasma spray material, 16 kinds of materials shown in Table 1 were manufactured by the atomization method. In FIG. 1, NO.
Optical micrograph of surface morphology of atomized powder (3) (100
2 times) is shown as a representative.
【００１６】[0016]
【表１】 [Table 1]
【００１７】次に、これらの粉末を用いて径：５０．６
ｍｍ、厚さ：６ｍｍの炭素鋼管にプラズマ溶射を実施し
た。溶射条件はプラズマガスがＡｒ：４５リットル／分
＋Ｈ2 ：４リットル／分、プラズマアーク電流が６００
Ａ、プラズマ電圧が６０Ｖ、溶射距離が１００〜１５０
ｍｍである。次にこれを１１００℃で１０分間電気炉中
で加熱し封孔処理を実施した。Next, using these powders, the diameter: 50.6
Plasma spraying was performed on a carbon steel tube having a thickness of 6 mm and a thickness of 6 mm. The thermal spraying conditions were as follows: plasma gas Ar: 45 liters / min + H 2 : 4 liters / min, plasma arc current 600
A, plasma voltage 60V, spraying distance 100-150
mm. Next, this was heated in an electric furnace at 1100 ° C. for 10 minutes to carry out a sealing treatment.
【００１８】〇（実施例の効果） 図２に、上記表１中のＮＯ．３のアトマイズ粉を溶射
し、封孔処理した後の光学顕微鏡写真（１００倍）を示
す。また、表２は表１中のＮＯ．１〜１６の材料を溶射
し封孔処理を行った後の断面からの硬さ測定結果を示
す。◯ (Effects of the embodiment) FIG. 2 shows NO. The optical microscope photograph (100 times) after spraying the atomized powder of 3 and carrying out a sealing treatment is shown. In addition, Table 2 shows NO. The hardness measurement result from the cross section after thermally spraying the materials 1 to 16 and performing the sealing treatment is shown.
【００１９】[0019]
【表２】 [Table 2]
【００２０】表２から判るように、ＮＯ．１〜１３の硬
さはＭａｘ２６５以下であるが、本発明の範囲外で、Ｃ
ｒまたはＭｏまたはＣｕの量が多いＮＯ．１４，１５，
１６はＭａｘ：３００〜３５０と高硬度を示しており、
割れが発生する可能性をしさしている。As can be seen from Table 2, NO. The hardness of 1 to 13 is Max265 or less, but outside the scope of the present invention,
r. or Mo or Cu with a large amount of NO. 14, 15,
16 has a high hardness of Max: 300 to 350,
It indicates the possibility of cracking.
【００２１】次に硫酸環境中での耐食性を調査するため
に、表１中のＮＯ．１〜１３を５０℃に加熱した５０％
硫酸環境中で腐食試験を実施した。その結果を表３に示
す。Next, in order to investigate the corrosion resistance in a sulfuric acid environment, NO. 50% of 1 ~ 13 heated to 50 ℃
The corrosion test was carried out in a sulfuric acid environment. Table 3 shows the results.
【００２２】[0022]
【表３】 [Table 3]
【００２３】表３から判るように、本発明の範囲外でＣ
ｒ量の少ないＮＯ．１，２、Ｍｏ量の少ないＮＯ．４，
９及びＣｕ量の少ないＮＯ．５，１０は腐食量が４．２
〜３０．６ｇ／ｍ2 ・ｈｒと大きい値を示している。こ
れに対して、本発明の範囲内にあるＮＯ．３，５，６，
７，８，１１，１２及び１３は０．２〜０．４ｇ／ｍ2
・ｈｒの範囲内にあり良好な耐食性を示すことがわかっ
た。As can be seen from Table 3, C is outside the scope of the present invention.
NO. 1, 2 and NO. 4,
9 and NO. 5 and 10 have a corrosion amount of 4.2
It shows a large value of up to 30.6 g / m 2 · hr. On the other hand, NO. 3, 5, 6,
7, 8, 11, 12, and 13 are 0.2 to 0.4 g / m 2
-It was found that it was in the range of hr and showed good corrosion resistance.
【００２４】以上の結果より、主としてＣｒ：１５〜３
０ｗｔ％、Ｓｉ：８〜１０ｗｔ％、Ｍｏ：３〜１０ｗｔ
％、Ｃｕ：１〜３ｗｔ％、Ｎｉ：残部よりなる自溶性合
金の耐食性は組織安定性もよく、また硫酸環境中で良好
な耐食性を示すことがわかる。なお、溶射後の封孔処理
を行う方法としては、電気炉中で加熱する方法以外に、
高周波加熱あるいはガス火炎などによる方法を用いても
よい。From the above results, mainly Cr: 15 to 3
0 wt%, Si: 8-10 wt%, Mo: 3-10 wt%
%, Cu: 1-3 wt%, Ni: balance of the self-fluxing alloy has good structure stability and good corrosion resistance in a sulfuric acid environment. As a method of performing the sealing treatment after thermal spraying, other than the method of heating in an electric furnace,
A method using high frequency heating or gas flame may be used.
【００２５】[0025]
【発明の効果】本発明により、組織安定性が良好で優れ
た耐硫酸露点腐食性を示す伝熱管が提供できる。According to the present invention, a heat transfer tube having good structure stability and excellent sulfuric acid dew point corrosion resistance can be provided.
【図１】本発明の一実施例で使用する自溶性合金のアト
マイズ粉の表面状態を示す光学顕微鏡写真。FIG. 1 is an optical micrograph showing a surface state of atomized powder of a self-fluxing alloy used in one example of the present invention.
【図２】本発明の一実施例で使用する自溶性合金のアト
マイズ粉を伝熱管上に溶射した後、封孔処理を施した皮
膜の状況を示す光学顕微鏡写真。FIG. 2 is an optical micrograph showing the state of a film that has been subjected to sealing treatment after atomizing powder of a self-fluxing alloy used in one example of the present invention is sprayed on a heat transfer tube.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 篠原 正朝 長崎県長崎市深堀町五丁目717番１号 三 菱重工業株式会社長崎研究所内 (72)発明者 納富 啓 長崎県長崎市深堀町五丁目717番１号 三 菱重工業株式会社長崎研究所内 (72)発明者 斉藤 正洋 長崎県長崎市深堀町五丁目717番１号 三 菱重工業株式会社長崎研究所内 (72)発明者 西尾 敏昭 長崎県長崎市深堀町五丁目717番１号 三 菱重工業株式会社長崎研究所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masanobu Shinohara 5-717-1, Fukahori-cho, Nagasaki-shi, Nagasaki Sanryo Heavy Industries Ltd. Nagasaki Research Institute (72) Inventor Kei Kei Natomi 5-chome, Fukahori-cho, Nagasaki-shi, Nagasaki No. 717-1 Sanryo Heavy Industries Co., Ltd. Nagasaki Research Institute (72) Inventor Masahiro Saito 5-717, Fukahori-cho, Nagasaki-shi, Nagasaki Sanryo Heavy Industry Co., Ltd. Nagasaki Research Institute (72) Inventor Toshiaki Nishio Nagasaki, Nagasaki Prefecture 5-717-1, Fukahori-cho Sanritsu Heavy Industries Ltd. Nagasaki Research Center
Claims (1)
０ｗｔ％、Ｍｏ：３〜１０ｗｔ％、Ｃｕ：１〜３ｗｔ
％、Ｎｉ：残部よりなる自溶性合金被覆耐硫酸露点腐食
用伝熱管。1. Cr: 15 to 30 wt%, Si: 8 to 1
0wt%, Mo: 3-10wt%, Cu: 1-3wt
%, Ni: Self-fluxing alloy coated heat transfer tube for sulfuric acid dew point corrosion consisting of the balance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20677995A JPH0931576A (en) | 1995-07-21 | 1995-07-21 | Heat transfer tube for sulfuric acid dew point corrosion resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20677995A JPH0931576A (en) | 1995-07-21 | 1995-07-21 | Heat transfer tube for sulfuric acid dew point corrosion resistance |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0931576A true JPH0931576A (en) | 1997-02-04 |
Family
ID=16528954
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20677995A Pending JPH0931576A (en) | 1995-07-21 | 1995-07-21 | Heat transfer tube for sulfuric acid dew point corrosion resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0931576A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6326063B1 (en) | 1998-01-29 | 2001-12-04 | Tocalo Co., Ltd. | Method of production of self-fusing alloy spray coating member |
-
1995
- 1995-07-21 JP JP20677995A patent/JPH0931576A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6326063B1 (en) | 1998-01-29 | 2001-12-04 | Tocalo Co., Ltd. | Method of production of self-fusing alloy spray coating member |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 20020423 |