Firmansyah, Rizal Gibran Alif (2025) Laporan Magang Industri : Analisis Evaluasi Kinerja Sebelum Dan Sesudah Maintenance Kebocoran Pada Tube “Rotor Cooling Air” Cooler GT Blok 2.3 PT. PLTGU Grati. Project Report. [s.n.]. (Unpublished)
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Abstract
Rotor Cooling Air (RCA) Cooler merupakan komponen vital pada sistem Pembangkit Listrik Tenaga Gas dan Uap (PLTGU) yang berfungsi menjaga suhu operasional rotor generator agar tetap aman dan mencegah terjadinya overheating. Pada unit GT Blok 2.3 PLTGU Grati, ditemukan indikasi gangguan berupa kemunculan gelembung udara pada sight glass saluran keluar (outlet) air pendingin yang disebabkan oleh keretakan (leakage) pada sisi tube akibat faktor thermal cycling dan masa pakai (life time). Penelitian ini bertujuan untuk mengevaluasi dan membandingkan kinerja termal Shell and Tube Heat Exchanger (STHE) tipe U-tube pada tabung RCA sebelum dan sesudah dilakukannya tindakan corrective maintenance berupa metode penyumbatan (plugging) dan pengelasan. Evaluasi parameter termal dilakukan menggunakan metode Log Mean Temperature Difference (LMTD) dan efektivitas ($\epsilon$-NTU) berdasarkan data operasi riil dari Central Control Room (CCR). Hasil analisis menunjukkan bahwa setelah dilakukan perbaikan, penurunan suhu udara keluar rotor menjadi lebih optimal dari 160°C menjadi 140°C. Secara kuantitatif, nilai efektivitas ($\epsilon$) RCA Cooler meningkat secara signifikan dari 47,35% menjadi 58,45% (kenaikan relatif sebesar 23,44%). Peningkatan ini didukung oleh kenaikan nilai Number of Transfer Units (NTU) sebesar 74,69% (dari 0,1434 menjadi 0,2505) serta pemulihan koefisien perpindahan panas menyeluruh ($U$) dari 7,37 W/m²°C menjadi 12,87 W/m²°C. Dengan demikian, tindakan corrective maintenance terbukti berhasil memulihkan kapasitas perpindahan panas aktual serta meningkatkan keandalan sistem pendinginan pada blok pembangkit.
========================================================================================================================The Rotor Cooling Air (RCA) Cooler is a vital component in a Combined Cycle Gas Turbine (CCGT) power plant system, designed to maintain the operational temperature of the generator rotor and prevent overheating. In the GT Block 2.3 unit at PLTGU Grati, a malfunction indication was discovered through the appearance of air bubbles in the cooling water outlet sight glass, caused by tube-side cracking (leakage) due to thermal cycling and operating lifetime factors. This study aims to evaluate and compare the thermal performance of the U-tube type Shell and Tube Heat Exchanger (STHE) inside the RCA vessel before and after corrective maintenance, utilizing plugging and welding methods. The evaluation of thermal parameters was conducted using the Log Mean Temperature Difference (LMTD) and effectiveness ($\epsilon$-NTU) methods based on actual operational data from the Central Control Room (CCR). The analysis results indicate that after the repair, the rotor outlet air temperature drop became more optimal, decreasing from 160°C to 140°C. Quantitatively, the RCA Cooler's effectiveness ($\epsilon$) significantly increased from 47.35% to 58.45% (a relative increase of 23.44%). This improvement is supported by a 74.69% increase in the Number of Transfer Units (NTU) value (from 0.1434 to 0.2505) and the recovery of the overall heat transfer coefficient (U) from 7.37 W/m²°C to 12.87 W/m²°C. Thus, the corrective maintenance action successfully restored the actual heat transfer capacity and enhanced the reliability of the cooling system in the power generation block.
| Item Type: | Monograph (Project Report) |
|---|---|
| Uncontrolled Keywords: | Kata Kunci: PLTGU, Rotor Cooling Air, Shell and Tube Heat Exchanger, LMTD, Efektivitas-NTU, Corrective Maintenance. ======================================================================================================================== Keywords: PLTGU, Rotor Cooling Air, Shell and Tube Heat Exchanger, LMTD, Effectiveness-NTU, Corrective Maintenance. |
| Subjects: | T Technology > TJ Mechanical engineering and machinery T Technology > TJ Mechanical engineering and machinery > TJ174 Maintenance and repair of machinery T Technology > TJ Mechanical engineering and machinery > TJ778 Gas turbines |
| Divisions: | Faculty of Vocational > Mechanical Industrial Engineering (D4) |
| Depositing User: | Rizal Gibran Alif Firmansyah |
| Date Deposited: | 21 Jul 2026 06:03 |
| Last Modified: | 21 Jul 2026 06:03 |
| URI: | http://repository.its.ac.id/id/eprint/135883 |
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