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題名 | 汽機轉子葉根破裂之非破壞檢測技術研發=Development of NDE Techniques for Turbine Blade Root Cracking |
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作者 | 吳永豪; 吳世先; 蕭祝阴; 黃圭珍; 蘇詠舜; 魏健能; | 書刊名 | 台電工程月刊 |
卷期 | 580 1996.12[民85.12] |
頁次 | 頁87-105 |
分類號 | 448.2 |
關鍵詞 | 非破壞檢測; 汽機; 葉片; Nondestructive inspection; Steam turbine; Blade; |
語文 | 中文(Chinese) |
中文摘要 | 蒸汽發電廠近年來曾陸續發生數起葉片破裂或停機的事件,結果造成為 數可觀的營運、財物損失。目前除了破裂原因未明而尚無根本解決之道,現行非 破壤檢測亦有不足之處。有鑑於此,本計畫乃針對西屋式葉片的根部破裂,希望 研究較新的渦電流及超音波檢測技術,以便在不拆卸葉片的情況下執行檢測進而 提高檢測可靠度來維持電廠的安全運轉及增加營運效益。 針對外露式的葉根端面破裂,研究過程分成六個階段,分別是:1.檢測問題的剖 析,2.檢測法評估,3.檢測法研發,4.功能測試及評估,5.檢測法建立,及6.檢測 法應用。目前我們已完成一套自動化渦電流檢測系統及相關之裂縫檢測技術,其 中的掃瞄器可用於汽機轉子L.2級或L1級葉片之檢測,實驗室的分析證實該系統 可檢出長度Imm以下的裂縫;而現場實測證實掃描功能及精度達到原先的設計需 求,但實際的裂縫偵測解析度則有賴其它的現場檢測來驗證。 另一方面,針對內藏式的葉根溝槽破裂,研究的重點是要設法找出一種適切的超 音法檢測法或程序,研究結果顯示,超音波換能器可以在葉片彎向外的曲面上掃 描並檢出位於葉根彎向內中央區域,DXL=2mmX5mm的凹槽人工瑕疵,而位於葉 根彎向內出汽側的頂部,DXL=5mmX5mm的凹槽也可以檢出。不過,目前所採用 的換能器,其高度尚需減小3mm左右方能執行這項檢測。 |
英文摘要 | In the past few years, there had been several cases of bladefailures or related unscheduled outages of steam power plants.These events had resulted in enormous lost generation andexpense to the utilities. So far, more than an inability to find aradical solution due to unclear root-cause, it actuallyrevealed an incompleteness of the current NDE for turbineblades. In view of this, we intend to develop supplementaryeddy - current and ultrasonic techniques to inspect the rootcracking on Westing-house blades in-situs. By means ofthese techniques, the plant performance and availability areexpected to be improved in terms of the increased reliability. For those exposed root cracks on end faces, the researchprogram was divided into six stages which included: l.inspec-tion problem analysis 2.inspection method analysis S.inspectionmethod development 4.performance analysis 5-inspection tech-nique establishment 6-implementation. At present, we havedeveloped an automatic eddy-current inspection system andrelevant crack detection technique. The system comprises ascanner which was designed for inspecting the steam turbine L-2 blade and also for L-lblade. Experimental results andmock-up test showed that the system can detect cracksshorter than 1mm; field test also showed an satisfactoryscanning performance and the accuracy as originally designed.However, the actual resolution of crack detection is to beverified by further field test. On the other hand, for hidden cracks between serration,the main objective is to find an appropriate ultrasonic method or procedure. Experimental results showed that we can use theconvex surface of the blade as the scanning surface, andnotches greater than DXL=2mmX5mm on the concave side inthe central region of blade root is detectable. For similarnotches on the concave side of blade root and close to thetrailing edge, the detectable dimension is greater than DXL=5mm X 5mm. Nevertheless, the height of the probe employed inour experiment should be further reduced by 3mm in order offit into the space between disks. |
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