Analisis Modifikasi Geometri Bucket Debris Filter Berbasis CFD pada Sistem Open Cycle Cooling Water PLTU Nagan Raya

Debris filter merupakan komponen penting pada Open Cycle Cooling Water System PLTU yang berfungsi sebagai penyaring terakhir air laut sebelum memasuki kondensor. Geometri bucket yang kurang hidrodinamis dapat menyebabkan peningkatan differential pressure, turbulensi aliran, serta beban mekanis pada sistem backwash, sehingga berpotensi mengganggu keandalan operasi debris filter. Penelitian ini bertujuan menganalisis pengaruh modifikasi geometri bucket debris filter terhadap karakteristik aliran fluida menggunakan metode Computational Fluid Dynamics (CFD) sebagai dasar rekomendasi perbaikan desain pada PLTU Nagan Raya. Simulasi dilakukan menggunakan metode Finite Volume Method dengan model turbulensi standar k-ε pada tiga konfigurasi bucket, yaitu bucket standar, bucket modifikasi dengan radius kelengkungan R=500 mm, dan R=700 mm. Parameter yang dianalisis meliputi distribusi kecepatan, distribusi tekanan, pola aliran (pathline), turbulensi, serta gaya yang bekerja pada bucket. Hasil simulasi menunjukkan bahwa modifikasi bucket berprofil lengkung mampu menghasilkan distribusi aliran yang lebih homogen, mengurangi turbulensi, meningkatkan gaya hisap menuju saluran backwash, serta memperbaiki karakteristik gaya yang bekerja pada bucket dibandingkan desain standar. Di antara variasi yang diuji, bucket dengan radius kelengkungan R=500 mm menunjukkan performa terbaik berdasarkan karakteristik aliran dan peningkatan gaya tangensial. Oleh karena itu, desain bucket dengan radius kelengkungan R=500 mm direkomendasikan sebagai alternatif perbaikan debris filter pada PLTU Nagan Raya.

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The debris filter is a critical component of the Open Cycle Cooling Water System in a coal-fired power plant (CFPP), serving as the final filtration stage for seawater before it enters the condenser. A bucket geometry with poor hydrodynamic characteristics can increase differential pressure, induce flow turbulence, and impose greater mechanical loads on the backwash system, thereby reducing the operational reliability of the debris filter. This study aims to analyze the effect of bucket geometry modification on the fluid flow characteristics of a debris filter using Computational Fluid Dynamics (CFD) as a basis for design improvement recommendations for the Nagan Raya Coal-Fired Power Plant. The simulations were performed using the Finite Volume Method (FVM) with the standard k-ε turbulence model on three bucket configurations: the original bucket, a modified bucket with a curvature radius of R=500 mm, and a modified bucket with a curvature radius of R=700 mm. The analyzed parameters included velocity distribution, pressure distribution, flow patterns (path lines), turbulence, and forces acting on the bucket. The simulation results indicated that the curved bucket designs provide a more uniform flow distribution, reduce flow turbulence, enhance the suction force toward the backwash channel, and improves the force characteristics acting on the bucket compared to the standard design. Among the configurations evaluated, the bucket with a curvature radius of R=500 mm exhibited the best performance based on flow characteristics and the increased tangential force. Therefore, a bucket design with a curvature radius of R=500 mm is recommended as an alternative improvement for the debris filter at Nagan Raya Coal-Fired Power Plant.