Analisis Kerusakan Combustor Basket pada Turbin Gas

Amalia, Lia (2017) Analisis Kerusakan Combustor Basket pada Turbin Gas. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Combustor basket merupakan komponen di dalam sistem ruang bakar pada turbin gas yang berfungsi sebagai tempat terjadinya proses pembakaran. Setelah 2000 jam operasi, ditemukan kerusakan berupa hotspot dan lubang pada material combustor basket. Kerusakan tersebut diketahui setelah terjadinya trip temperatur spread yang melebihi batas yang diijinkan. Penyebab kerusakan tersebut harus diketahui agar kerusakan serupa tidak terjadi lagi, oleh sebab itu perlu dilakukan analisis kegagalan pada material combustor basket.
Penelitian dilakukan dimulai dengan studi lapangan untuk mendapatkan data operasi dan data komponen combustor basket. Material yang tidak rusak diuji komposisi kimia dengan menggunakan XRF untuk mengetahui tipe paduan. Pengamatan visual dilakukan pada daerah sekitar lubang untuk mengetahui perubahan warna permukaan bagian dalam dan luar. Pengukuran ketebalan material, serta pengujian metalografi juga dilakukan untuk mengetahui perubahan struktur mikro dan korelasinya terhadap hasil pengamatan visual. Di sekitar lubang, pengujian EDX akan dilakukan untuk mendeteksi apakah ada unsur yang tidak sesuai.
Dari pengujian XRF di outer surface, diketahui material combustor basket merupakan Hastelloy-X. Pengamatan visual menunjukkan material di dekat lubang terpapar temperatur tinggi secara lokal, terlihat dari warna inner surface di sekitar lubang yang berwarna coklat muda. Pengujian XRF di inner surface menunjukkan inner surface merupakan lapisan TBC. Pada material dengan inner surface berwarna coklat muda, terdapat presipitat yang ukurannya semakin besar di dekat lubang dan membentuk network di batas butir. Berdasarkan pengujian SEM EDX, presipitat kaya akan unsur Cr dan Mo sehingga dapat disimpulkan presipitat merupakan karbida M23C6 atau M6C. Terbentuknya karbida yang kaya akan unsur Cr menyebabkan unsur Cr di matriks berkurang sehingga ketahanan material terhadap korosi temperatur tinggi. Berdasarkan hasil pengamatan dan pengujian material, kerusakan berupa lubang pada material combustor basket disebabkan oleh kerusakan lapisan pelindung yaitu lapisan APS TBC, sehingga logam induk terpapar lingkungan gas hasil pembakaran. Lapisan APS TBC rusak akibat terpapar temperatur secara siklik dan mengakibatkan crack, hal ini diperparah dengan paparan aliran gas hasil pembakaran berkecepatan tinggi.
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Combustor basket is a component inside the
combustion chamber in a gas turbine which is functioning as a place where combustion of fuel occurs. After 2000 hours of operation, failure in the form of holes and hotspots are found on the combustor basket material. The failure was found after a spread temperature trip which went beyond the allowable limit. The cause of failure should be analyzed so that similar failure may not happen anymore, therefore a failure analysis of the combustor basket material is needed.
The research began with field study to get operational and combustor basket components data. The undamaged material underwent chemical composition test using XRF method to determine the type of alloy. At the area near the hole, visual observation was done to determine color change of inner and outer surface, as well a
s material thickness measurement, and metallography inspection to determine microstructural change and its correlation to visual observation results. Near the hole, EDX test was done to detect any foreign element.
XRF test at the outer surface showed that
the material used in the combustor basket is Hastelloy-X. Visual observation showed that the material near the hole was exposed to high temperature locally, shown by inner surface color near the hole which is light brown.
XRF test at the inner surface showed that the inner surface is TBC.
Inner surface which is light brown in color has precipitates which is bigger in size, as observed nearer to the hole. The precipitates grow and form a network in the grain boundary. From SEM-EDX observation, the precipitates are high in Cr and Mo content which indicates that the precipitates are M23C6 or M6C carbides. The formation of carbides which is rich in Cr
causes the matrix to lose its Cr content and therefore decreasing the resistance of hot corrosion.
Based on the observations and testing, the hole in the combustor basket was caused by the damage in the
protective coating, APS TBC, which caused the base material to be exposed to combustion gas environment. APS TBC was damaged due to cyclic temperature which will cause cracking, added with exposure of combustion gas flow with high speed.

Item Type:	Thesis (Undergraduate)
Additional Information:	RSM 620.112 6 Ama a
Uncontrolled Keywords:	Analisis kegagalan, Combustor basket, Lubang, failure analysis, combustor basket, hole
Subjects:	T Technology > TJ Mechanical engineering and machinery T Technology > TN Mining engineering. Metallurgy
Divisions:	Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User:	Lia Amalia .
Date Deposited:	30 Jan 2018 03:33
Last Modified:	30 Jan 2018 03:33
URI:	http://repository.its.ac.id/id/eprint/45446

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