Sinaga, Halim Godfa Sinaga (2026) Studi Numerik dan Analitik Pengaruh Variasi Excess Air Terhadap Distribusi Temperatur Gas Buang Dan Laju Perpindahan Panas Pada Pipa Medium Reheater Boiler Tangentially Fired 315MW. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Pengaturan udara pembakaran memengaruhi karakteristik aliran, proses pembakaran, distribusi temperatur gas buang, dan perpindahan panas pada boiler. Penelitian ini menganalisis pengaruh pengurangan suplai udara sebesar 0%, 5%, 10%, dan 15%, yang direpresentasikan oleh koefisien udara 1,00; 0,95; 0,90; dan 0,85, terhadap profil aliran, karakteristik pembakaran, serta perpindahan panas pada pipa medium reheater boiler tangentially fired 315 MW. Simulasi dilakukan menggunakan Computational Fluid Dynamics pada ANSYS Fluent dengan model Realizable k-ε, Discrete Ordinates, Species Transport, Discrete Phase Model, dan porous media. Temperatur pipa serta laju perpindahan panas per satuan panjang dianalisis menggunakan tahanan termal satu dimensi. Validasi terhadap data commissioning menghasilkan kesalahan temperatur furnace exit gas temperature dan outlet boiler masing-masing sebesar 2,616% dan 3,733%. Pengurangan suplai udara menurunkan kecepatan rata-rata flue gas pada bidang FEGT dari 9,59 m/s menjadi 8,26 m/s dan temperatur rata-rata FEGT dari 1.118,16°C menjadi 1.020,19°C. Laju massa O₂ menurun dari 13,53 kg/s menjadi 4,42 kg/s, CO meningkat dari 0,00250 kg/s menjadi 0,01984 kg/s, sedangkan CO₂ menurun dari 66,53 kg/s menjadi 64,42 kg/s. Tambahan karbon tidak terkonversi relatif terhadap kondisi aktual meningkat dari 0,0504 kg/s menjadi 0,6201 kg/s. Pada medium reheater, temperatur maksimum flue gas menurun dari 1.232,55 K menjadi 1.035,99 K, laju perpindahan panas per satuan panjang menurun dari 5.455,63 W/m menjadi 3.264,22 W/m, serta temperatur permukaan luar dan dalam pipa menurun dari 470,11°C dan 466,39°C menjadi 442,55°C dan 440,32°C. Hasil menunjukkan bahwa pengurangan suplai udara menurunkan ketersediaan oksigen, kesempurnaan pembakaran, energi termal flue gas, dan perpindahan panas pada pipa medium reheater.
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Combustion air regulation affects flow characteristics, combustion processes, flue gas temperature distribution, and heat transfer in boilers. This study analyzes the effects of reducing the air supply by 0%, 5%, 10%, and 15%, represented by air ratios of 1.00, 0.95, 0.90, and 0.85, respectively, on the flow profile, combustion characteristics, and heat transfer to the medium reheater tubes of a 315 MW tangentially fired boiler. Numerical simulations were conducted using Computational Fluid Dynamics in ANSYS Fluent by applying the Realizable k-εturbulence model, the Discrete Ordinates radiation model, the Species Transport model, the Discrete Phase Model, and a porous-media approach. Tube temperatures and the heat transfer rate per unit length were analytically evaluated using a one-dimensional thermal-resistance method. Validation against commissioning data resulted in errors of 2.616% for the Furnace Exit Gas Temperature and 3.733% for the boiler outlet temperature. Reducing the air supply decreased the average flue gas velocity at the FEGT plane from 9.59 m/s to 8.26 m/s and the average FEGT from 1,118.16°C to 1,020.19°C. The O₂ mass flow rate decreased from 13.53 kg/s to 4.42 kg/s, the CO mass flow rate increased from 0.00250 kg/s to 0.01984 kg/s, and the CO₂ mass flow rate decreased from 66.53 kg/s to 64.42 kg/s. Additional unconverted carbon relative to the actual operating condition increased from 0.0504 kg/s to 0.6201 kg/s. In the medium reheater zone, the maximum flue gas temperature decreased from 1,232.55 K to 1,035.99 K, while the heat transfer rate per unit length decreased from 5,455.63 W/m to 3,264.22 W/m. The outer and inner tube-surface temperatures decreased from 470.11°C and 466.39°C to 442.55°C and 440.32°C, respectively. These results indicate that reducing the air supply decreases oxygen availability, combustion completeness, flue gas thermal energy, and heat transfer to the medium reheater tubes.
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | Boiler Tangentially Fired, Computational Fluid Dynamics, Excess Air, Medium Reheater, Porous Media, Perpindahan Panas. Computational Fluid Dynamics, Excess Air, Heat Transfer, Medium Reheater, Porous Media, Tangentially Fired Boiler. |
| Subjects: | T Technology > TJ Mechanical engineering and machinery > TJ263 Heat exchangers |
| Divisions: | Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21201-(S1) Undergraduate Thesis |
| Depositing User: | Halim Godfa Sinaga |
| Date Deposited: | 04 Aug 2026 06:14 |
| Last Modified: | 04 Aug 2026 06:14 |
| URI: | http://repository.its.ac.id/id/eprint/143126 |
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