Yudistya, Hendi (2025) Studi Numerik Pengaruh Co-Firing Sawdust Pada Variasi Elevasi Injeksi dan Air Staging Terhadap Karakteristik Pembakaran dan Emisi Untuk Tangentially Fired Pulverized Coal Boiler 350 MW. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Penggunaan energi fosil terus meningkat, mendorong emisi gas buang yang lebih tinggi. Untuk mencapai Net Zero Emission (NZE), pemerintah menargetkan peningkatan bauran energi terbarukan. Namun, kontribusinya masih rendah dibandingkan energi fosil. Oleh karena itu, dibutuhkan transisi energi bertahap, salah satunya melalui pemanfaatan biomassa sebagai bahan bakar campuran (co-firing) di PLTU. Penelitian ini berfokus pada pengoptimalan co-firing biomassa sawdust dan batubara di boiler dengan dilakukan injeksi biomassa pada elevasi yang berbeda-beda. Kemudian diamati pengaruhnya terhadap karakteristik pembakaran dan emisi gas buang. Metode co-firing ini dinilai dapat mengatasi permasalahan penyesuaian pulverizer mills karena menggiling campuran batubara dan biomassa dengan sifat fisik dan mekanik berbeda. Penelitian ini menggunakan metode komputasi fluida dengan software Ansys Fluent, berdasarkan kondisi eksisting boiler berkapasitas 350 MW. Penelitian terdiri dari enam variasi elevasi yaitu A,B,C,D,E, dan F. Kemudian dari variasi elevasi paling optimal dilakukan variasi fraksi Separated Over-Fired Air (SOFA) sebesar 0%,5%,10%,15%, 20%, dan 25% disimulasikan. Hasil menunjukkan, dengan naiknya elevasi injeksi sawdust secara signifikan menurunkan temperatur FEGT dan meningkatkan temperatur outlet boiler. Terjadi fenomena delay combustion, karena perbedaan karakteristik pembakaran batubara dengan sawdust. Selain itu, seiring variasi injeksi dari A ke F, terjadi penurunan fraksi massa CO2, peningkatan fraksi massa CO, SO2 cenderung konstan, NOx cenderung konstan, dan efisiensi boiler menurun hingga 2,61%, dari 81,1% ke 78,49%. Berdasarkan penilaian parameter emisi dan efisiensi, didapatkan kondisi optimum pada injeksi 10% sawdust elevasi A (case 1). Penyesuaian rasio SOFA dari 0% hingga 25%, secara efektif menekan temperatur puncak hingga 34℃. Akan tetapi, temperatur outlet meningkat seiring peningkatan rasio SOFA. Dengan meningkatnya rasio SOFA, menggeser pembakaran ke zona boiler upper. Seiring peningkatan rasio udara SOFA dari 0% hingga 25%, emisi CO2 dan CO memiliki tren meningkat, emisi NOx cenderung menurun, tren emisi SO2 cenderung konstan, dan efisiensi boiler menurun hingga 1,58%, dari 79,17% ke 77,59%. Berdasarkan penilaian parameter emisi dan efisiensi boiler, didapatkan kondisi optimum pada variasi 5% SOFA.
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The increasing use of fossil energy continues to drive higher exhaust gas emissions. To achieve Net Zero Emission (NZE), the government aims to increase the share of renewable energy. However, its contribution remains significantly lower than that of fossil fuels. Therefore,
a gradual energy transition is necessary, one approach being the utilization of biomass as a co-firing fuel in coal-fired power plants (CFPPs). This study focuses on optimizing the co-firing of sawdust biomass and coal in a boiler by injecting biomass at different elevations, then observing its effects on combustion characteristics and flue gas emissions. The co-firing method is considered effective in addressing pulverizer mill adjustment issues caused by the differing physical and mechanical properties of coal and biomass. Computational fluid dynamics (CFD) simulations were carried out using Ansys Fluent software, based on a 350 MW boiler. The study included six injection elevation variations: A, B, C, D, E, and F. After determining the most
optimal injection elevation, simulations were conducted with varying Separated Over-Fired Air (SOFA) fractions of 0%, 5%, 10%, 15%, 20%, and 25%. The results showed that increasing the sawdust injection elevation significantly decreased the Final Exit Gas Temperature (FEGT) while increasing the boiler outlet temperature. A delay in combustion occurred due to the different combustion characteristics between coal and sawdust. Additionally, as the injection elevation varied from A to F, there was a decrease in CO2 mass fraction, an increase in CO mass fraction, SO2 showed a relatively constant trend, NOx remained steady, and boiler efficiency
decreased by up to 2,61%, from 81,1% to 78,49%. Based on emissions and efficiency parameters, the optimum condition was found at 10% sawdust injection at elevation A (case 1).
Adjusting the SOFA ratio from 0% to 25% effectively reduced the peak temperature by up to 34°C. However, the outlet temperature increased with higher SOFA ratios, as combustion
shifted to the upper zone of the boiler. As the SOFA air ratio increased from 0% to 25%, CO2 and CO emissions showed an upward trend, NOx emissions tended to decrease, SO2 emissions remained relatively constant, and boiler efficiency declined by up to 1,58%, from 79,17% to 77,59%. Based on the evaluation of emission and efficiency parameters, the optimum condition was achieved at 5% SOFA variation.
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | Co-firing, Elevasi, Emisi, Sawdust, Separated Over-Fired Air, Co-firing, Elevation, Emission, Sawdust, Separated Over-Fired Air |
| Subjects: | T Technology > TJ Mechanical engineering and machinery > TJ164 Power plants--Design and construction T Technology > TJ Mechanical engineering and machinery > TJ254.7 Combustion chambers T Technology > TJ Mechanical engineering and machinery > TJ263.5 Boilers (general) T Technology > TJ Mechanical engineering and machinery > TJ265.E23 Thermodynamics. |
| Divisions: | Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21201-(S1) Undergraduate Thesis |
| Depositing User: | Hendi Yudistya |
| Date Deposited: | 31 Jul 2025 08:04 |
| Last Modified: | 31 Jul 2025 08:04 |
| URI: | http://repository.its.ac.id/id/eprint/124817 |
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