JP5459712B2 - Corrosion site identification method and sulfide corrosion diagnosis method - Google Patents
Corrosion site identification method and sulfide corrosion diagnosis method Download PDFInfo
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Description
本発明は、石炭を燃焼する火炉を備えるボイラのボイラ蒸発管やボイラ水冷壁管に生じた硫化腐食の部位を特定することができる腐食部位の特定方法及び硫化腐食の診断方法に関する。 The present invention relates to a method for identifying a corrosion site and a diagnostic method for sulfide corrosion that can identify a site of sulfurization corrosion that has occurred in a boiler evaporation pipe or a boiler water-cooled wall tube of a boiler having a furnace that burns coal.
近年、石炭などを燃焼する火力発電設備では、環境に対する配慮などの観点から、低ＮＯＸ運転を強化しているが、これにより、火力ボイラの炉内に強い還元性雰囲気が形成され、火炉内壁面のボイラ蒸発管等が硫化腐食により減肉速度が増大するという問題が生じている。 In recent years, in the thermal power plants burning coal, in view of environmental considerations, but to enhance the low NO X operation, thereby, a strong reducing atmosphere is formed in the furnace of the thermal power boiler, furnace There has been a problem that the wall thinning rate of the boiler evaporator tube and the like increases due to sulfide corrosion.
ボイラ蒸発管等に硫化腐食が生じた場合、超音波を用いた測定機器などで管の残肉厚を測定することにより腐食部位の特定と腐食状況を診断し（例えば、非特許文献１参照）、必要に応じて補修を行っている。ボイラ蒸発管の表面には、スケールや、石炭が燃焼されて生じた石炭灰や石炭に含まれる微量金属等の付着物があるため、硫化腐食した部位の特定に先立って、スケールおよび付着物をサンドブラストなどで除去する必要がある。 When sulfidation corrosion occurs in a boiler evaporation tube, etc., the corrosion thickness is determined by measuring the remaining thickness of the tube with an ultrasonic measuring instrument or the like (for example, see Non-Patent Document 1). Repairs are performed as necessary. Since there are deposits such as scales, coal ash produced by burning coal, and trace metals contained in the coal on the surface of the boiler evaporator tube, the scale and deposits should be removed prior to the identification of the sites that have undergone sulfidation corrosion. It must be removed by sandblasting.
ボイラ蒸発管の硫化腐食は一様に生じるのではなく、炉内雰囲気の還元性の強さが各所で異なれば、硫化腐食の程度もボイラ蒸発管の各部位で異なる。補修を要する腐食部位の特定のためには、ボイラ蒸発管の広範囲にわたってサンドブラスト処理を実施したり、試行錯誤的に各部位にサンドブラスト処理を実施したりして、各部位の腐食状況を診断する必要があり、腐食部位の特定に手間や費用が掛かってしまうという問題がある。 The sulfidation corrosion of the boiler evaporator tube does not occur uniformly. If the strength of the reducing atmosphere in the furnace atmosphere is different in each part, the degree of sulfidation corrosion also varies in each part of the boiler evaporator tube. In order to identify the corrosion sites that require repair, it is necessary to diagnose the corrosion status of each site by performing sand blasting over a wide range of the boiler evaporator tube or by performing sand blasting on each site by trial and error. There is a problem that it takes time and cost to specify the corrosion site.
本発明は、このような事情に鑑み、ボイラ蒸発管等の硫化腐食した部位を簡便に特定することができる腐食部位の特定方法及び、当該特定方法で特定した部位の硫化腐食の状況を診断する硫化腐食の診断方法を提供することを目的とする。 In view of such circumstances, the present invention diagnoses the state of sulfidation corrosion at a site identified by the identification method and a method for identifying a corrosion site that can easily identify a site that has undergone sulfidation corrosion such as a boiler evaporator tube. An object is to provide a diagnostic method for sulfide corrosion.
本願の発明者は、ボイラ蒸発管の各部位において、表面に付着した付着物を分析し、また、当該部位の硫化腐食の状況を診断したところ、付着物に含まれる亜鉛の濃度と硫化腐食の状況に相関があることを見出し、本発明を完成するに至った。 The inventor of the present application analyzed deposits adhering to the surface in each part of the boiler evaporation tube and diagnosed the state of sulfide corrosion of the part. As a result, the concentration of zinc contained in the deposits and sulfide corrosion The present inventors have found that there is a correlation in the situation and have completed the present invention.
上記課題を解決する本発明の第１の態様は、石炭を燃焼する火炉の内壁面に生じた硫化腐食の部位を特定する腐食部位の特定方法であって、内壁面の付着物の成分を分析し、前記付着物の成分の亜鉛の重量パーセント濃度が、石炭灰中の亜鉛の濃度よりも濃い場合には、当該付着物を分析した部位において硫化腐食が生じていると判定することを特徴とする腐食部位の特定方法にある。火炉の内壁面とは、火炉の内部の表面を総称したものであり、例えば、ボイラ蒸発管やボイラ水冷壁管等の表面である。 A first aspect of the present invention that solves the above problem is a method of identifying a corrosion site that identifies a site of sulfidation corrosion that has occurred on the inner wall surface of a furnace that burns coal, and analyzes the components of deposits on the inner wall surface When the weight percentage concentration of zinc as a component of the deposit is higher than the concentration of zinc in coal ash, it is determined that sulfidation corrosion has occurred at the site where the deposit is analyzed. It is in the method of identifying the corrosion site. The inner wall surface of the furnace is a general term for the inner surface of the furnace, and is, for example, the surface of a boiler evaporation tube, a boiler water-cooled wall tube, or the like.
かかる第１の態様では、火炉の内壁面、すなわちボイラ蒸発管等の表面の付着物の成分を分析し、付着物の亜鉛濃度を測定するだけで硫化腐食が生じた部位を特定することができる。これにより、従来のサンドブラスト処理・肉厚検査等を実施する場合に比べて、各段に早く、かつ費用を抑えることができる。 In such a first aspect, it is possible to identify the site where sulfidation corrosion has occurred simply by analyzing the components of deposits on the inner wall of the furnace, that is, on the surface of the boiler evaporator tube, etc., and measuring the zinc concentration of the deposits. . Thereby, compared with the case where the conventional sandblasting process, thickness inspection, etc. are implemented, each stage can be carried out earlier and cost can be reduced.
本発明の第２の態様は、第１の態様に記載する腐食部位の特定方法において、内壁面の複数部位で付着物を分析し、硫化亜鉛の質量パーセント濃度が相対的に高い付着物を分析した部位では、硫化亜鉛の重量パーセント濃度が相対的に低い付着物を分析した部位よりも硫化腐食が進んでいると判定することを特徴とする腐食部位の特定方法にある。 According to a second aspect of the present invention, in the method for identifying a corrosion site described in the first aspect, the deposit is analyzed at a plurality of sites on the inner wall surface, and the deposit having a relatively high mass percentage concentration of zinc sulfide is analyzed. The method of identifying a corrosion site is characterized in that it is determined that sulfidation corrosion is more advanced than the site analyzed for deposits having a relatively low weight percent concentration of zinc sulfide.
かかる第２の態様では、火炉の内壁面の複数部位のうち、相対的に硫化腐食が進んだ部位を特定することができる。 In the second aspect, it is possible to specify a portion where sulfidation corrosion has progressed relatively among a plurality of portions on the inner wall surface of the furnace.
本発明の第３の態様は、第１又は第２の態様に記載する腐食部位の特定方法により硫化腐食が生じていると特定された部位から付着物を除去し、当該部位において硫化腐食の状態を診断することを特徴とする硫化腐食の診断方法にある。 According to a third aspect of the present invention, deposits are removed from a site identified as having undergone sulfidation corrosion by the method for identifying a corrosion site described in the first or second aspect, and the state of sulfidation corrosion at the site. This is a method for diagnosing sulfide corrosion, characterized by
かかる第３の態様では、火炉の内壁面を網羅的にサンドブラスト処理・肉厚検査を行うよりも効率的に硫化腐食の状況を診断することができる。 In the third aspect, the state of sulfide corrosion can be diagnosed more efficiently than when the inner wall surface of the furnace is comprehensively subjected to sandblasting and thickness inspection.
本発明によれば、ボイラ蒸発管等の硫化腐食した部位を簡便に特定することができる腐食部位の特定方法及び、当該特定方法で特定した部位の硫化腐食の状況を診断する硫化腐食の診断方法が提供される。 ADVANTAGE OF THE INVENTION According to this invention, the identification method of the corrosion site | part which can specify easily the site | part which carried out the sulfide corrosion of the boiler evaporation pipe etc., and the diagnostic method of the sulfide corrosion which diagnoses the situation of the sulfide corrosion of the site | part specified by the said specific method Is provided.
以下、本発明の実施形態に係る腐食部位の特定方法を図面に基づき詳細に説明する。 Hereinafter, a method for identifying a corrosion site according to an embodiment of the present invention will be described in detail with reference to the drawings.
図１に示すように、石炭燃焼装置１が有する火炉２の周囲には、複数のバーナ３が設けられており、バーナ３は微粉炭路７を介して石炭粉砕装置８とそれぞれ繋がっている。石炭粉砕装置８は石炭を貯留するホッパ９にそれぞれ接続されており、ホッパ９には石炭が投入される。 As shown in FIG. 1, a plurality of burners 3 are provided around a furnace 2 included in the coal combustion apparatus 1, and the burners 3 are connected to a coal pulverization apparatus 8 through pulverized coal passages 7, respectively. The coal crusher 8 is connected to a hopper 9 that stores coal, and the hopper 9 is charged with coal.
ホッパ９に石炭を投入すると、所定量の石炭が石炭粉砕装置８に運ばれる。そして、石炭は、石炭粉砕装置８により、所望の粒径に調整されて微粉炭となる。 When coal is introduced into the hopper 9, a predetermined amount of coal is conveyed to the coal crusher 8. The coal is adjusted to a desired particle size by the coal crusher 8 to become pulverized coal.
微粉炭は、微粉炭路７を介して空気で搬送され、火炉２に投入される。この微粉炭は搬送した空気と共に燃焼され、さらに、火炉２の上部に設けられた上段空気ノズル４から空気が供給されて燃焼される。 The pulverized coal is conveyed by air through the pulverized coal passage 7 and is put into the furnace 2. The pulverized coal is burned together with the conveyed air, and further, air is supplied from the upper air nozzle 4 provided in the upper part of the furnace 2 and burned.
このようにして、下段に設けられたバーナ３及び上段空気ノズル４から火炉２に送り込まれる空気により、微粉炭が火炉２の中で完全燃焼する。火炉２で燃焼した微粉炭は燃焼灰となり、一部は火炉２の下部にある石炭灰排出口５から排出され、排ガスは火炉２の上方に設けられた排出口６から、集塵装置などの排ガス処理装置（図示せず）に排出される。 In this way, the pulverized coal is completely burned in the furnace 2 by the air sent to the furnace 2 from the burner 3 and the upper air nozzle 4 provided in the lower stage. The pulverized coal burned in the furnace 2 becomes combustion ash, a part is discharged from the coal ash discharge port 5 at the lower part of the furnace 2, and the exhaust gas is discharged from the discharge port 6 provided above the furnace 2 to a dust collector or the like. It is discharged to an exhaust gas treatment device (not shown).
石炭燃焼装置１は、例えば、バーナ３と上段空気ノズル４との間の空間で空気不足の燃焼を促進し、上段空気ノズル４から火炉２出口までの空間で燃焼反応を完結させる運転を行う。このような運転においては、排出口６でのＮＯＸ濃度を低減出来るが、バーナ３と上段空気ノズル４との間には還元性雰囲気が形成され、その雰囲気の下で火炉２の内壁面の一例であるボイラ蒸発管１０の表面において、硫化腐食が進行する。 For example, the coal combustion apparatus 1 performs an operation of promoting combustion with insufficient air in a space between the burner 3 and the upper air nozzle 4 and completing a combustion reaction in a space from the upper air nozzle 4 to the furnace 2 outlet. In such operation, but it can be reduced concentration of NO X at the outlet 6, between the burner 3 and the upper air nozzles 4 a reducing atmosphere is formed, the inner wall surface of the furnace 2 under the atmosphere Sulfide corrosion proceeds on the surface of the boiler evaporator tube 10 as an example.
硫化腐食の進行の程度は、運転条件などにより、ボイラ蒸発管１０の各所で異なり、また、ボイラ蒸発管１０の表面には付着物が付着した状態となる。 The degree of progress of sulfidation corrosion varies depending on the operating conditions, etc., in various places of the boiler evaporator tube 10, and deposits are attached to the surface of the boiler evaporator tube 10.
このような状態の石炭燃焼装置１を対象として、本実施形態に係る腐食部位の特定方法について詳細に説明する。 A method for identifying a corrosion site according to the present embodiment will be described in detail for the coal combustion apparatus 1 in such a state.
まず、石炭燃焼装置１の定期点検などの休止中に、蛍光Ｘ線分析装置を用いて、ボイラ蒸発管１０の表面の付着物の成分を分析する。付着物とは、石炭が燃焼されて生じた石炭灰がボイラ蒸発管１０の表面に固着したり、石炭に含まれる微量成分がボイラ蒸発管１０の表面に析出したものである。 First, the component of the deposit on the surface of the boiler evaporator tube 10 is analyzed using a fluorescent X-ray analyzer during a periodical check of the coal combustion apparatus 1. The deposits are coal ash generated by burning coal and sticking to the surface of the boiler evaporator tube 10, or trace components contained in the coal are deposited on the surface of the boiler evaporator tube 10.
分析は、ボイラ蒸発管１０の表面のうち、１つまたは複数の部位を対象に行う。分析の結果、各部位の付着物ごとに、各成分の付着物全体に占める重量パーセント濃度が得られる。なお、分析する部位に特に限定はなく、また、ボイラ蒸発管１０の表面に付着した状態の付着物を分析する場合に限らず、ボイラ蒸発管１０の表面から付着物を採取し、その付着物を分析してもよい。 The analysis is performed on one or more parts of the surface of the boiler evaporator tube 10. As a result of the analysis, a weight percent concentration of each component in the entire deposit is obtained for each deposit. In addition, there is no limitation in particular in the site | part to analyze, and it is not restricted to the case of analyzing the deposit | attachment of the state adhering to the surface of the boiler evaporation pipe 10, A deposit | attachment is extract | collected from the surface of the boiler evaporation pipe 10, and the deposit | attachment May be analyzed.
次に、このような分析により得られた付着物の亜鉛の重量パーセント濃度が、石炭灰の亜鉛の重量パーセント濃度よりも濃くなっているかを比較する。石炭灰の亜鉛の重量パーセント濃度は、石炭を燃焼して得られた石炭灰の成分を分析することにより得ておく。 Next, it is compared whether the weight percent concentration of zinc in the deposit obtained by such an analysis is higher than the weight percent concentration of zinc in coal ash. The weight percent concentration of zinc in coal ash is obtained by analyzing the components of coal ash obtained by burning coal.
石炭灰に含まれる亜鉛の重量パーセント濃度と比較して、ボイラ蒸発管１０の各部位の付着物に含まれる亜鉛の重量パーセント濃度が濃いならば、その部位では硫化腐食が生じていると判定する。 If the weight percent concentration of zinc contained in the deposits of each part of the boiler evaporator tube 10 is higher than the weight percent concentration of zinc contained in the coal ash, it is determined that sulfidation corrosion has occurred at that part. .
ここで、上述した亜鉛の濃化と硫化腐食との関係について説明する。 Here, the relationship between the above-described zinc concentration and sulfide corrosion will be described.
還元性雰囲気である火炉２内では、ボイラ蒸発管１０に腐食生成物の代表的化合物である硫化鉄（ＦｅＳ）が生成するが、この雰囲気の下では、亜鉛は硫化亜鉛（ＺｎＳ）の状態が安定であることが挙げられる。 In the furnace 2 which is a reducing atmosphere, iron sulfide (FeS), which is a representative compound of corrosion products, is generated in the boiler evaporator tube 10. Under this atmosphere, zinc is in a state of zinc sulfide (ZnS). It is mentioned that it is stable.
図２は、５００℃、１気圧のＦｅ−Ｏ−Ｓ系及びＺｎ−Ｏ−Ｓ系の相安定状態図であり、図３は、１２００℃、１気圧の相安定状態図である。１２００℃は、火炉２で微粉炭が燃焼されているときの燃焼ガスの温度近傍であり、５００℃は、燃焼時のボイラ蒸発管１０の温度近傍である。各図とも、縦軸は硫黄ガスの分圧、横軸は酸素ガスの分圧を表している。 FIG. 2 is a phase stability diagram of the Fe—O—S system and Zn—O—S system at 500 ° C. and 1 atmosphere, and FIG. 3 is a phase stability diagram of 1200 ° C. and 1 atmosphere. 1200 ° C. is in the vicinity of the temperature of the combustion gas when pulverized coal is burned in the furnace 2, and 500 ° C. is in the vicinity of the temperature of the boiler evaporator tube 10 at the time of combustion. In each figure, the vertical axis represents the partial pressure of sulfur gas, and the horizontal axis represents the partial pressure of oxygen gas.
図２（ａ）及び図３（ａ）に示すように、Ｆｅ−Ｏ−Ｓ系において硫化鉄が安定であるときの硫黄ガスの分圧と酸素ガスの分圧の範囲においては、図２（ｂ）及び図３（ｂ）に示すように、Ｚｎ−Ｏ−Ｓ系において硫化亜鉛が安定的である。 As shown in FIG. 2A and FIG. 3A, in the range of the partial pressure of sulfur gas and the partial pressure of oxygen gas when iron sulfide is stable in the Fe—O—S system, As shown in b) and FIG. 3B, zinc sulfide is stable in the Zn—O—S system.
硫化亜鉛は、燃焼ガス中では気体で存在するが、１１８０℃において昇華するため、ボイラ燃焼ガス（１３００〜１４００℃程度）中の硫化亜鉛ガスは、ボイラ蒸発管１０表面において冷却され選択的に固相析出する。 Zinc sulfide exists as a gas in the combustion gas, but sublimates at 1180 ° C., so the zinc sulfide gas in the boiler combustion gas (about 1300 to 1400 ° C.) is cooled on the surface of the boiler evaporator 10 and selectively solidified. Phase precipitation.
図４は、ボイラ蒸発管表面に亜鉛が析出する過程を模式的に示した図である。図示するように、ボイラ蒸発管１０表面には、燃焼ガス中の灰粒子や硫化亜鉛が付着する。燃焼ガスに含まれる固体又は液体の灰成分がボイラ蒸発管１０表面に衝突することにより灰粒子が付着する。 FIG. 4 is a diagram schematically showing the process of depositing zinc on the boiler evaporation tube surface. As shown in the figure, ash particles and zinc sulfide in the combustion gas adhere to the surface of the boiler evaporation tube 10. As the solid or liquid ash component contained in the combustion gas collides with the boiler evaporation tube 10 surface, the ash particles adhere.
燃焼ガス中に含まれる気体の硫化亜鉛は、ボイラ蒸発管１０表面で冷却され固体として析出する。燃焼ガス中の亜鉛濃度は、低濃度であるが、昇華による析出のため、その他の灰成分の物理的な付着と異なり、付着物中の濃度が高くなっていく。また、亜鉛は、既に付着した灰成分の空隙にも析出する。 The gaseous zinc sulfide contained in the combustion gas is cooled on the surface of the boiler evaporator tube 10 and deposited as a solid. The concentration of zinc in the combustion gas is low, but due to precipitation by sublimation, the concentration in the deposit becomes higher, unlike the physical deposition of other ash components. Zinc also deposits in the voids of the ash component that has already adhered.
このように、硫化腐食が生じる還元性雰囲気では、燃焼ガス中に硫化亜鉛が安定的に存在し、ボイラ蒸発管１０表面で昇華により選択的に固相析出するため、ボイラ蒸発管１０表面で亜鉛が濃化すると考えられる。したがって、ボイラ蒸発管１０の各部位の付着物に含まれる亜鉛が濃化しているならば、その部位では硫化腐食が生じていると判定することができる。 Thus, in a reducing atmosphere in which sulfidation corrosion occurs, zinc sulfide is stably present in the combustion gas, and is selectively solid-phase precipitated by sublimation on the boiler evaporation tube 10 surface. Is thought to thicken. Therefore, if the zinc contained in the deposits at each part of the boiler evaporation pipe 10 is concentrated, it can be determined that sulfur corrosion has occurred at that part.
以上に説明した腐食部位の特定方法によれば、ボイラ蒸発管１０表面の各部位に付着したままの付着物を分析し、その結果として得られる亜鉛の濃度から、その部位において硫化腐食が生じているか否かを判定することができる。すなわち、ボイラ蒸発管１０の表面の付着物を計測してボイラ蒸発管１０の腐食部位を非破壊で特定することができる。 According to the method for identifying a corrosion site described above, the deposits that remain attached to each site on the surface of the boiler evaporator tube 10 are analyzed, and from the resulting zinc concentration, sulfide corrosion occurs at that site. It can be determined whether or not. That is, the corrosion part of the boiler evaporation pipe 10 can be specified nondestructively by measuring the deposits on the surface of the boiler evaporation pipe 10.
また、従来においては、サンドブラスト処理などでスケールや付着物を除去し、超音波厚さ計を用いた肉厚測定などにより腐食部位を特定したが、このようなサンドブラスト処理が不要となり、極めて早く現場において腐食部位の特定が可能となり、また、費用の削減も可能となる。 In the past, scales and deposits were removed by sandblasting, etc., and the corrosion site was identified by measuring the thickness using an ultrasonic thickness gauge. In this case, it is possible to specify the corrosion site and to reduce the cost.
本実施形態では、ボイラ蒸発管１０は主に鉄からなるが、表面にNi-50Cr溶射材などの耐硫化腐食コーティングが施工されたボイラ蒸発管１０についても同様に本発明を適用することができる。この場合、付着物の亜鉛濃度が高い部位は、より強い還元性雰囲気に晒された部位として特定することができる。これにより、本発明に係る腐食部位の特定方法は、当該コーティングの経年的な点検補修や、経過観察を必要とする部位の絞り込みにも適用できる。 In this embodiment, the boiler evaporating tube 10 is mainly made of iron, but the present invention can be similarly applied to the boiler evaporating tube 10 whose surface is provided with a sulfide corrosion resistant coating such as a Ni-50Cr sprayed material. . In this case, the site | part with a high zinc concentration of a deposit | attachment can be specified as a site | part exposed to the stronger reducing atmosphere. Thereby, the identification method of the corrosion site | part which concerns on this invention is applicable also to narrowing down the site | part which requires aged inspection repair of the said coating, and follow-up observation.
また、腐食部位を特定した後は、その部位に対して、サンドブラスト処理を行ってスケールおよび付着物を除去し、当該部位において超音波厚さ計などを用いた肉厚検査を実施することで、腐食状況を詳細に診断してもよい。このような硫化腐食の診断によれば、ボイラ蒸発管１０の表面を網羅的にサンドブラスト処理・肉厚検査を行うよりも効率的に硫化腐食の状況を診断することができる。 In addition, after specifying the corrosion site, by removing the scale and deposits by sandblasting the site, by performing a thickness inspection using an ultrasonic thickness meter or the like at the site, Corrosion conditions may be diagnosed in detail. According to such diagnosis of sulfidation corrosion, the state of sulfidation corrosion can be diagnosed more efficiently than when the surface of the boiler evaporator tube 10 is comprehensively subjected to sandblasting and thickness inspection.
なお、本実施形態では、ボイラ蒸発管１０の複数部位における付着物の亜鉛の濃度を測定し、相対的に濃度が高い部位について硫化腐食が生じていると判定したが、このような場合に限定されない。すなわち、付着物に含まれる亜鉛濃度が、石炭灰に含まれる亜鉛の濃度よりも濃化しているならば、硫化腐食が生じている部位と判定してもよい。 In the present embodiment, the concentration of zinc in the deposits at a plurality of parts of the boiler evaporator tube 10 is measured and it is determined that sulfidation corrosion has occurred at a relatively high concentration part. However, the present invention is limited to such a case. Not. That is, if the concentration of zinc contained in the deposit is higher than the concentration of zinc contained in the coal ash, it may be determined that the site has undergone sulfidation corrosion.
また、石炭を燃焼する火炉２を備える石炭燃焼設備１について説明したが、石炭のみを燃焼する場合に限定されない。例えば、石炭と共にバイオマス由来の燃料など他の燃料を混焼する場合においても、火炉の内壁面における腐食部位を特定することができる。 Moreover, although the coal combustion facility 1 provided with the furnace 2 which burns coal was demonstrated, it is not limited to the case of burning only coal. For example, even when another fuel such as a biomass-derived fuel is co-fired with coal, the corrosion site on the inner wall surface of the furnace can be specified.
以下、本発明の腐食部位の特定方法の実施例を示す。図１に示した火炉２の各部位Ａ〜Ｅにおいて付着物を蛍光Ｘ線分析装置で分析し、表１に示す結果が得られた（単位は重量パーセント濃度である。）。 Examples of the method for identifying a corrosion site according to the present invention will be described below. The deposits were analyzed with a fluorescent X-ray analyzer at each of the parts A to E of the furnace 2 shown in FIG. 1, and the results shown in Table 1 were obtained (unit is weight percent concentration).
石炭には、亜鉛や硫黄などの微量成分が含まれており、表１に示すように、石炭が燃焼された石炭灰中からはそれらの微量成分が測定される。部位Ｃ〜Ｅにおいては、硫黄（Ｓ）の重量パーセント濃度は、０．２〜０．５であり、亜鉛（Ｚｎ）の重量パーセント濃度は、０．８〜２．１であるのに対し、部位Ａ〜Ｂにおいては、硫黄の重量パーセント濃度は、１２．５〜１６．３であり、亜鉛の重量パーセント濃度は、４２．８〜４３．３と、明らかに濃度が高くなっている。 Coal contains trace components such as zinc and sulfur, and as shown in Table 1, these trace components are measured from the coal ash in which the coal is burned. In sites C-E, the weight percent concentration of sulfur (S) is 0.2-0.5, and the weight percent concentration of zinc (Zn) is 0.8-2.1, whereas In parts A to B, the weight percent concentration of sulfur is 12.5 to 16.3, and the weight percent concentration of zinc is 42.8 to 43.3, which is clearly higher.
表２に、石炭灰の成分の分析例を示す（出典は、財団法人石炭技術研究所編「第１０回石炭利用技術研究発表会講演集」）。 Table 2 shows an analysis example of the components of coal ash (Source: Coal Technology Research Institute, “10th Coal Technology Research Presentation Lecture”).
表２には、フライアッシュとクリンカアッシュの微量成分が示されている。フライアッシュは、石炭を石炭燃焼装置１で燃焼したあと、集じん装置で集められたものであり、クリンカアッシュは、石炭灰排出口５で回収された溶結状の石炭灰を砕いたものである。同表に示すように、亜鉛の濃度は、フライアッシュの平均で１５９ｐｐｍである。 Table 2 shows the minor components of fly ash and clinker ash. The fly ash is obtained by burning coal in the coal combustion device 1 and then collected by the dust collector, and the clinker ash is obtained by pulverizing the welded coal ash collected at the coal ash discharge port 5. . As shown in the table, the concentration of zinc is 159 ppm on the average of fly ash.
表１及び表２から、付着物に含まれる亜鉛の重量パーセント濃度は、石炭灰の亜鉛の重量パーセント濃度よりも濃くなっており、その中でも、部位Ａ〜Ｂで採取された付着物の亜鉛濃度は他の部位Ｃ〜Ｅよりも遙かに高い。 From Table 1 and Table 2, the weight percent concentration of zinc contained in the deposit is higher than the weight percent concentration of zinc in coal ash, and among these, the zinc concentration in the deposit collected at sites A to B Is much higher than the other sites CE.
すなわち、石炭に含まれる微量成分の一つである亜鉛は、石炭灰にはｐｐｍオーダーの量だけ含まれているにも関わらず、ボイラ蒸発管１０の付着物には数十％程度含まれている。このように、表１の亜鉛以外の微量元素についてはこのような濃化が見られず、亜鉛だけが濃化している。 That is, zinc, which is one of the trace components contained in coal, is contained in the deposits of the boiler evaporation tube 10 in the order of several tens of percent, even though the coal ash contains only an amount on the order of ppm. Yes. Thus, such a concentration is not seen about trace elements other than zinc of Table 1, and only zinc is concentrated.
上述した付着物の分析結果から、亜鉛が濃化している部位Ａ〜Ｂは、硫化腐食が生じている可能性が高いと判定することができる。表３に、部位Ａ〜Ｅの腐食状況を実測した結果を示す（STBA21とは、火力発電用鋼として認可されている低合金鋼である。）。 From the analysis result of the deposits described above, it can be determined that the portions A to B where zinc is concentrated are highly likely to have sulfidation corrosion. Table 3 shows the results of actual measurement of the corrosion status of the parts A to E (STBA21 is a low alloy steel approved as a thermal power generation steel).
表３に示すように、亜鉛が濃化している部位Ａ〜Ｂについては、補修を必要とする程度に硫化腐食により減肉が生じていることが確認できた。 As shown in Table 3, it was confirmed that the portions A to B where the zinc was concentrated were thinned due to sulfidation corrosion to the extent that repair was necessary.
本発明は、硫化腐食の腐食部位を特定し、必要に応じて点検補修を行うことを要する産業分野で利用することができる。 INDUSTRIAL APPLICABILITY The present invention can be used in an industrial field in which a corrosion site of sulfidation corrosion is specified and inspection and repair are required as necessary.
１ 石炭燃焼装置
２ 火炉
３ バーナ
４ 上段空気ノズル
５ 石炭灰排出口
６ 排出口
７ 微粉炭路
８ 石炭粉砕装置
９ ホッパ
１０ ボイラ蒸発管
DESCRIPTION OF SYMBOLS 1 Coal combustion apparatus 2 Furnace 3 Burner 4 Upper air nozzle 5 Coal ash discharge port 6 Discharge port 7 Coal pulverization channel 8 Coal crushing device 9 Hopper 10 Boiler evaporation pipe
Claims (3)
内壁面の付着物の成分を分析し、
前記付着物の成分の亜鉛の重量パーセント濃度が、石炭灰中の亜鉛の濃度よりも濃い場合には、当該付着物を分析した部位において硫化腐食が生じていると判定する
ことを特徴とする腐食部位の特定方法。 A method of identifying a corrosion site that identifies a site of sulfide corrosion that has occurred on the inner wall of a furnace that burns coal,
Analyzing the components of the deposits on the inner wall,
When the weight percentage concentration of zinc as a component of the deposit is higher than the concentration of zinc in coal ash, it is determined that sulfidation corrosion has occurred at the site where the deposit was analyzed. How to identify the site.
内壁面の複数部位で付着物を分析し、
硫化亜鉛の質量パーセント濃度が相対的に高い付着物を分析した部位では、硫化亜鉛の重量パーセント濃度が相対的に低い付着物を分析した部位よりも硫化腐食が進んでいると判定する
ことを特徴とする腐食部位の特定方法。 In the method for identifying a corrosion site according to claim 1,
Analyzing deposits at multiple locations on the inner wall,
It is judged that sulfidation corrosion is judged to be more advanced at the site analyzed for deposits with a relatively high weight percent concentration of zinc sulfide than at the site analyzed for deposits with a relatively low weight percent concentration of zinc sulfide. The method of identifying the corrosion site.
当該部位において硫化腐食の状態を診断する
ことを特徴とする硫化腐食の診断方法。 The deposit is removed from the site identified as sulfidation corrosion by the method for identifying a corrosion site according to claim 1 or claim 2,
A diagnostic method for sulfide corrosion characterized by diagnosing the state of sulfide corrosion at the relevant site.
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