Halim, Halim (2021) Studi Numerik Efek Variasi Sudut Tilting Burner dan Coal Optimization terhadap Karakteristik Pembakaran pada Tangentially Fired Pulverized-Coal Boiler 350 MWe (Studi Kasus PLTU Pelabuhan Ratu Unit 2). Masters thesis, Institut Teknologi Sepuluh November.
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Abstract
PLTU Pelabuhan Ratu merupakan pembangkit listrik dengan tipe tangentially fired pulverized coal boiler yang didesain menggunakan batubara 4000 - 4200 kcal/kg LHV (4500 - 4700 kcal/kg HHV). Untuk mengoptimalkan biaya bahan bakar, dilakukan perubahan spesifikasi batubara menjadi lignite kategori A yaitu 3500-4200 kcal/kg HHV. Penurunan kualitas batubara yang dikonsumsi boiler ini selanjutnya disebut coal optimization. Nilai kalori batubara yang digunakan dalam coal optimization ini adalah 4080 kcal/kg HHV. Akan tetapi, walaupun secara ekonomi terlihat menguntungkan, coal optimization ini tentunya akan berdampak terhadap operasi dan pemeliharaan boiler karena beberapa permasalahan yang berpotensi muncul akibat kualitas batubara yang lebih rendah dari desain. Salah satu fasilitas pembakaran yang dioptimalkan saat coal optimization ini adalah burner tilting. Untuk itu perlu dilakukan studi mengenai efek tilting burner dan coal optimization terhadap pembakaran di boiler.
Studi dilakukan secara numerik dengan menggunakan Computational Fluid Dynamics (CFD). Pembuatan geometri boiler menggunakan software Gambit dan simulasi numerik menggunakan software ANSYS Fluent. Simulasi dilakukan dengan melakukan variasi sudut tilting burner -30°, -20°, -10°, 0°, dan +5°. Jumlah batubara dan udara pembakaran untuk setiap variasi sudut tilting burner adalah sama. Hasil simulasi menunjukkan bahwa sudut tilting mempengaruhi posisi fireball di dalam furnace boiler, semakin keatas sudut tilting burner, semakin ke atas juga posisi fireball, dan sebaliknya. Ketika posisi fireball berada dibawah maka panas yang diserap oleh walltube akan lebih banyak sehingga panas yang dikirim ke outlet furnace dan area konveksi akan lebih sedikit sehingga menurunkan FEGT dan temperatur flue gas di area konveksi, dan sebaliknya.
Saat coal optimization dengan nilai kalori 4080 kcal/kg, sudut tilting yang paling optimal, relatif terhadap sudut lain yang divariasikan, adalah -30° dengan pertimbangan (1) FEGT dan deviasi yang paling kecil antara temperatur flue gas hasil simulasi dengan desain di area konveksi yaitu masing-masing sebesar 1237,01 °C dan 22,82 °C. (2) Kandungan O2 pada outlet boiler yang paling sedikit, yaitu 3,27%. (3) Kandungan CO2 pada outlet boiler yang paling banyak, yaitu 17,60%. Akan tetapi, sudut tilting -30° menghasilkan NOx yang paling besar, yaitu 1,72e-07%.
Kata kunci: pembakaran, coal optimization, tilting burner, CFD
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PLTU Pelabuhan Ratu is a Tangentially Fired pulverized coal boiler type designed to use 4000 - 4200 kcal/kg LHV (4500 - 4700 kcal/kg HHV) coal. To optimize fuel costs, the coal specification was changed to lignite category A, which is 3500-4200 kcal/kg HHV. The decrease in coal quality consumed by the boiler is hereinafter referred to as coal optimization. The coal calorific value used in this coal optimization is 4080 kcal/kg HHV. However, even though it looks economically profitable, coal optimization will certainly have impacts on the operation and maintenance of the boiler because of several problems that could potentially arise due to lower coal quality than the design. One of the combustion facilities that is optimized during this coal optimization is the tilting burner. For this reason, it is necessary to study the effect of tilting burner and coal optimization on boiler combustion.
The study was carried out numerically using Computational Fluid Dynamics (CFD). Boiler geometry made using Gambit software and numerical simulation using ANSYS Fluent software. The simulation was carried out by varying the burner tilt angle -30°, -20°, -10°, 0°, and +5°. The amount of coal and combustion air for each variation of burner tilt angle is the same. The simulation results show that the burner tilt angle affects the position of the fireball in the boiler furnace, the higher the burner tilt angle, the higher the fireball position, and vice versa. When the fireball position is lower, the heat absorbed by the wall tube will be higher so that the heat sent to the furnace outlet and convection area will be less, thus lowering the FEGT and flue gas temperature in the convection area, and vice versa.
The most optimum tilting angle when using coal with a calorific value of 4080 kcal/kg is -30° with consideration of (1) FEGT and the smallest deviation between the simulated flue gas temperature and the design in the convection area are 1237.01 °C and 22.82 °C, respectively. (2) The least O2 content at the boiler outlet, which is 3.27%. (3) The most CO2 content at the boiler outlet, which is 17.60%. However, the tilting angle of -30° produces the largest NOx, which is 1.72e-07%.
Keywords: combustion, coal optimization, tilting burner, CFD
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | pembakaran, combustion, coal optimization, tilting burner, CFD |
| Subjects: | T Technology > TJ Mechanical engineering and machinery > TJ164 Power plants--Design and construction |
| Divisions: | Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21101-(S2) Master Thesis |
| Depositing User: | Halim Halim |
| Date Deposited: | 23 Aug 2021 12:04 |
| Last Modified: | 25 Aug 2021 02:45 |
| URI: | http://repository.its.ac.id/id/eprint/89871 |
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