Analisis Numerik Pengaruh Pembakaran Batu Bara Berkalori Rendah Terhadap Equivalent Stress Pada Platen Superheater Di Pulverized Coal Boiler

Zughlulun, Nabil (2026) Analisis Numerik Pengaruh Pembakaran Batu Bara Berkalori Rendah Terhadap Equivalent Stress Pada Platen Superheater Di Pulverized Coal Boiler. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Penggunaan batu bara berkalori rendah (low rank coal/LRC) melalui metode coal switching pada Pembangkit Listrik Tenaga Uap (PLTU) merupakan salah satu strategi untuk menekan biaya operasional. Namun, perubahan nilai kalor bahan bakar dapat memengaruhi karakteristik pembakaran sehingga berdampak pada distribusi temperatur flue gas, perpindahan panas, serta kondisi tegangan pada komponen platen superheater. Penelitian ini bertujuan untuk menganalisis pengaruh variasi nilai kalor batu bara terhadap distribusi temperatur flue gas, temperatur dinding pipa, gradien temperatur, thermal stress, mechanical stress, equivalent stress, serta safety factor pada platen superheater. Penelitian dilakukan menggunakan simulasi numerik tiga dimensi dengan pendekatan computational fluid dynamics (CFD) pada ANSYS Fluent untuk memperoleh karakteristik aliran fluida dan distribusi temperatur, kemudian dilanjutkan dengan analisis Static Structural dan Steady-State Thermal pada ANSYS Workbench untuk mengevaluasi distribusi temperatur dan kondisi tegangan pada material. Simulasi dilakukan pada empat variasi nilai kalor batu bara, yaitu 4000, 3800, 3600, dan 3400 kcal/kg. Hasil simulasi menunjukkan bahwa perubahan nilai kalor batu bara memengaruhi karakteristik termal pada area platen superheater. Temperatur maksimum flue gas tertinggi diperoleh pada variasi 3600 kcal/kg sebesar 1044,45°C, sedangkan kecepatan maksimum aliran steam tertinggi terjadi pada variasi 4000 kcal/kg sebesar 18,129 m/s. Analisis struktur menunjukkan bahwa thermal stress dipengaruhi oleh distribusi temperatur dan gradien temperatur, sedangkan mechanical stress relatif konstan karena tekanan internal steam dipertahankan tetap pada seluruh variasi. Interaksi kedua komponen tegangan tersebut menghasilkan equivalent stress maksimum sebesar 214,76 MPa pada pipa pelindung, 206,87 MPa pada pipa dalam terklem, dan 138,87 MPa pada pipa standar, yang seluruhnya terjadi pada variasi 3600 kcal/kg. Hasil evaluasi juga menunjukkan bahwa pipa pelindung memiliki safety factor terendah dibandingkan kedua jenis pipa lainnya, sehingga menjadi komponen yang paling kritis terhadap pembebanan termal. Dengan demikian, perubahan karakteristik pembakaran akibat penggunaan batu bara berkalori rendah berpengaruh terhadap distribusi temperatur, kondisi tegangan, dan tingkat keamanan struktur platen superheater, sehingga perlu dipertimbangkan dalam evaluasi keandalan komponen boiler.
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The use of low-rank coal (LRC) via coal switching in coal-fired power plants is a strategy to reduce operational costs. However, changes in the heating value of the fuel can affect combustion characteristics, thereby impacting the flue gas temperature distribution, heat transfer, and stress conditions on the platen superheater components. This study aims to analyze the effect of variations in coal heating value on the flue gas temperature distribution, tube wall temperature, temperature gradient, thermal stress, mechanical stress, equivalent stress, and safety factor of the platen superheater. The research was conducted using three-dimensional numerical simulations with a computational fluid dynamics (CFD) approach in ANSYS Fluent to obtain fluid flow characteristics and temperature distribution, followed by Steady-State Thermal and Static Structural analyses in ANSYS Workbench to evaluate the temperature distribution and stress conditions on the material. The simulations were performed on four variations of coal heating values: 4000, 3800, 3600, and 3400 kcal/kg. The simulation results show that changes in coal heating value affect the thermal characteristics in the platen superheater area. The highest maximum flue gas temperature was obtained at the 3600 kcal/kg variation at 1044.45°C, while the highest maximum steam flow velocity occurred at the 4000 kcal/kg variation at 18.129 m/s. The structural analysis indicates that thermal stress is influenced by the temperature distribution and temperature gradient, whereas mechanical stress remains relatively constant since the internal steam pressure was kept constant across all variations. The interaction of these two stress components resulted in a maximum equivalent stress of 214.76 MPa on the protecting tube, 206.87 MPa on the inner clamped tube, and 138.87 MPa on the standard tube, all of which occurred at the 3600 kcal/kg variation. The evaluation results also reveal that the protecting tube has the lowest safety factor compared to the other two types of tubes, making it the most critical component against thermal loading. Thus, changes in combustion characteristics due to the use of low-rank coal affect the temperature distribution, stress conditions, and structural safety level of the platen superheater, which needs to be considered in the reliability evaluation of boiler components.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	coal switching, computational fluid dynamics (CFD), equivalent stress, low rank coal, platen superheater, safety factor, thermal stress coal switching, computational fluid dynamics (CFD), equivalent stress, low-rank coal, platen superheater, safety factor, thermal stress.
Subjects:	T Technology > TJ Mechanical engineering and machinery > TJ263 Heat exchangers 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:	Nabil Zughlulun
Date Deposited:	31 Jul 2026 02:33
Last Modified:	31 Jul 2026 02:33
URI:	http://repository.its.ac.id/id/eprint/140238

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