Studi Numerik Pengaruh Coal Terhadap Karakteristik Pembakaran Dan Emisi Pada Tangential Fired Pulverized Coal Boiler 315 MW

Arief, Muhammad Mayzal Zidane (2026) Studi Numerik Pengaruh Coal Terhadap Karakteristik Pembakaran Dan Emisi Pada Tangential Fired Pulverized Coal Boiler 315 MW. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Pembangkit Listrik Tenaga Uap (PLTU) berbahan bakar batubara kualitas rendah (Low Rank Coal) masih menjadi tulang punggung penghasil listrik utama. Namun, fluktuasi karakteristik bahan bakar yang diterima seringkali menimbulkan tantangan signifikan terhadap stabilitas termal dan efisiensi operasional boiler. Penelitian ini berfokus pada pengaruh variasi komposisi batubara (Coal 4000, 3800, 3600 dan 3400) dengan kadar air atau moisture tinggi terhadap karakteristik pembakaran dan distribusi temperatur pada boiler jenis tangential fired pulverized coal di PLTU Pacitan. Penelitian dilakukan menggunakan perangkat lunak ANSYS Fluent untuk memprediksi profil termofluid di dalam furnace. Variasi penelitian yang digunakan meliputi Higher Heating Value yang berbeda serta 10% Over Fire Air guna menjaga kelebihan udara (excess air) tetap pada level 20% dengan kadar oksigen sebesar 21%. Hasil simulasi menunjukkan bahwa penurunan HHV tidak berbanding lurus dengan Furnace Exit Gas Temperature (FEGT), yang justru menunjukkan pola tidak monoton (1132°C hingga 1075°C) akibat kompetisi antara laju alir massa gas buang dan rasio udara-bahan bakar aktual (AFRact). Temperatur outlet flue gas economizer turut membentuk pola kurva U, dengan titik terendah pada HHV 3800 kcal/kg (352,7°C), sebagai hasil kompetisi antara efektivitas konveksi dan kapasitas termal gas buang. Fraksi massa CO2 menurun hingga 21,57% akibat efek dilusi oleh meningkatnya massa gas buang, bukan oleh penurunan produksi CO2 itu sendiri. Emisi CO melonjak signifikan pada kualitas batubara terendah (HHV 3400), mencapai 310,9 ppm, akibat akumulasi kandungan moisture tinggi, AFRact rendah, dan laju alir batubara besar yang menekan kelengkapan reaksi oksidasi CO menjadi CO2. Sementara itu, emisi NOx mengikuti pola kandungan nitrogen bahan bakar, bukan tren HHV, mengindikasikan dominasi mekanisme fuel-NOx. Berdasarkan temuan tersebut, penggunaan batubara dengan kualitas mendekati desain awal (HHV 4500) tetap menjadi skema paling optimum bagi kestabilan termal dan emisi boiler.
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Coal-fired power plants utilizing Low Rank Coal (LRC) remain the primary backbone of electricity generation. However, fluctuations in fuel characteristics often pose significant challenges to thermal stability and boiler operational efficiency. This study focuses on the influence of varying coal compositions (Coal 4000, 3800, 3600, and 3400) with high moisture content on combustion characteristics and temperature distribution within a tangential-fired pulverized coal boiler at the Pacitan Power Plant. The research was performed using ANSYS Fluent software to predict the thermofluid profile inside the furnace. The research parameters include different Higher Heating Value variations and 10% Over Fire Air to maintain a constant excess air level of 20% with an oxygen content of 21%. The results show that the Furnace Exit Gas Temperature (FEGT) does not decrease linearly with HHV, instead exhibiting a non-monotonic trend (1132°C to 1075°C) due to competition between the increasing flue gas mass flow rate and the decreasing actual air-fuel ratio (AFRact). The economizer outlet flue gas temperature also forms a U-shaped pattern, reaching its lowest point at HHV 3800 kcal/kg (352.7°C), as a result of competition between convective heat transfer effectiveness and the thermal capacitance of the flue gas. The CO2 mass fraction decreases by up to 21.57%, attributable to a dilution effect from the increasing total flue gas mass rather than an actual reduction in CO2 production. CO emissions rise sharply at the lowest coal quality (HHV 3400), reaching 310.9 ppm, driven by the combined effect of high moisture content, low AFRact, and high coal mass flow rate, which together suppress the completeness of CO-to-CO2 oxidation. Meanwhile, NOx emissions follow the trend of fuel-bound nitrogen content rather than HHV, indicating the dominance of the fuel-NOx formation mechanism. Based on these findings, operating with coal quality close to the original design specification (HHV 4500) remains the most optimal scheme for maintaining boiler thermal stability and emission control.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Boiler, Low Rank Coal, Karakteristik Pembakaran, Boiler, Low Rank Coal, Combustion Characteristics
Subjects:	T Technology > TJ Mechanical engineering and machinery > TJ164 Power plants--Design and construction
Divisions:	Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User:	Muhammad Mayzal Zidane Arief
Date Deposited:	31 Jul 2026 07:01
Last Modified:	31 Jul 2026 07:01
URI:	http://repository.its.ac.id/id/eprint/141033

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