Analisa Numerik Pengaruh Jumlah Primary Air Nozzle Terhadap Kondisi Hidrodinamik Fluidisasi Pada CFB Boiler

Izzulhaqqie, Muhammad Adim (2023) Analisa Numerik Pengaruh Jumlah Primary Air Nozzle Terhadap Kondisi Hidrodinamik Fluidisasi Pada CFB Boiler. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Tenaga listrik merupakan sumber energi penting pada zaman ini, terutama bagi negara Indonesia. Terdapat pembangkit listrik tenaga uap yang ada di Indonesia yang memiliki kapasitas sebesar 2 x 100 MW dengan menggunakan teknologi circulating fludized bed (CFB) boiler. Isu operasi dan pemeliharaan yang ada pada CFB boiler umumnya adalah kondisi fluidisasi yang buruk dan adanya degradasi komponen furnace akibat erosi. Diperlukan penelitian untuk mengetahui kondisi fluidisasi terhadap jumlah primary air nozzle pada CFB boiler dengan kapasitas 100 MW pada kondisi operasi rasio PA/SA sebesar 70/30.
Penelitian ini dilakukan dengan metode numerik menggunakan software CPFD Barracuda Virtual Reactor 22. Simulasi dilakukan dengan empat variasi jumlah primary air nozzle, yaitu: 504, 656, 824, dan 914. Pemodelan aliran gas-padat pada penelitian ini menggunakan pendekatan Eulerian-Lagrangian dengan model turbulen Large Eddy Simulation, model drag WenYu-Ergun, kondisi transien, dan dengan reaksi pembakaran. Hasil dari penelitian diperoleh distribusi fraksi volume partikel, tekanan, kecepatan partikel, temperatur, heat flux dinding, dan indeks erosi.
Hasil simulasi menunjukkan jumlah primary air nozzle berpengaruh terhadap proses fluidisasi di dalam furnace CFB boiler. Jumlah primary air nozzle yang lebih kecil memiliki dead zone yang lebih besar. Peningkatan jumlah primary air nozzle juga meningkatkan jumlah partikel yang tersuspensi dan homogenitas partikel sepanjang ketinggian furnace. Tekanan furnace cenderung meningkat seiring dengan peningkatan jumlah primary air nozzle karena jumlah partikel tersuspensi dalam aliran gas-padatan meningkat. Diperoleh bed pressure drop dari kasus 504 nozzle sebesar 11.207 Pa, kasus 656 nozzle sebesar 12.411 Pa, kasus 824 nozzle sebesar 12.918 Pa, dan kasus 914 nozzle sebesar 13.840 Pa. Peningkatan jumlah primary air nozzle juga meningkatkan kecepatan sirkulasi partikel dalam furnace sehingga dapat meningkatkan sirkulasi partikel internal. Temperatur gas dalam furnace, pada kasus 914 nozzle dapat dipertahankan lebih merata sepanjang ketinggian furnace dengan temperatur maksimal sebesar 1093 K. Sedangkan, kasus 504 nozzle memiliki temperatur maksimal sebesar 1094 K di daerah furnace bagian bawah namun berangsur turun seiring dengan ketinggian furnace. Pada kasus 914 nozzle didapatkan laju penyerapan panas total sebesar 162,27 MW, diikuti dengan kasus 824 nozzle sebesar 153,36 MW, kasus 656 nozzle sebesar 145,57 MW, dan kasus 504 nozzle sebesar 144,61 MW. Indeks erosi memiliki hubungan erat terhadap perbedaan pola fluidisasi dan kecepatan resirkulasi partikel bed. Jumlah nozzle yang lebih sedikit mengakibatkan fluidisasi lebih terlokalisir sehingga menunjukkan erosi yang lebih tinggi di tengah tembok. Sedangkan, jumlah nozzle yang lebih banyak menyebabkan indeks erosi lebih melandai dan tersebar di sepanjang dinding.
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Electricity is an essential source of energy in this era, especially for countries like Indonesia. There is a steam power plant in Indonesia with a capacity of 2 x 100 MW that uses circulating fluidized bed (CFB) boiler technology. The operational and maintenance issues commonly found in CFB boilers are poor fluidization conditions and component degradation due to erosion in the furnace. Research is needed to understand the fluidization conditions regarding the number of primary air nozzles in the 100 MW CFB boiler with an operating condition of a PA/SA ratio of 70/30.
This research is conducted using a numerical method with CPFD Barracuda Virtual Reactor 22 software. The simulation is performed with four variations of the number of primary air nozzles: 504, 656, 824, and 914. The gas-solid flow modeling in this study uses the Eulerian-Lagrangian approach with the Large Eddy Simulation turbulent model, the WenYu-Ergun drag model, transient conditions, and combustion reactions. The results of the research include particle volume fraction distribution, pressure, particle velocity, temperature, wall heat flux, and erosion index.
The simulation results show that the number of primary air nozzles affects the fluidization process inside the CFB boiler furnace. A smaller number of primary air nozzles result in a larger dead zone. Increasing the number of primary air nozzles also increases the amount of suspended particles and particle homogeneity along the height of the furnace. Furnace pressure tends to increase with the increasing number of primary air nozzles because the number of suspended particles in the gas-solid flow increases. The bed pressure drop is obtained as 11.207 Pa for the 504 nozzle case, 12.411 Pa for the 656 nozzle case, 12.918 Pa for the 824 nozzle case, and 13.840 Pa for the 914 nozzle case. Increasing the number of primary air nozzles also enhances the upward and downward particle movement in the furnace, thereby improving internal particle circulation. In the 914 nozzle case, gas temperature in the furnace can be maintained more evenly along its height, with a maximum temperature of 1093 K. Meanwhile, the 504 nozzle case has a maximum temperature of 1094 K in the lower furnace region, gradually decreasing with the furnace height. The total heat absorption rate in the 914 nozzle case is 162.27 MW, followed by 153.36 MW for the 824 nozzle case, 145.57 MW for the 656 nozzle case, and 144.61 MW for the 504 nozzle case. The erosion index is closely related to the difference in fluidization patterns and particle resirculation velocity in the bed. A smaller number of nozzles lead to more localized fluidization, resulting in higher erosion in the middle of the wall. On the other hand, a larger number of nozzles cause a more gradual and widespread erosion index along the wall.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Boiler, CFB, CPFD, Hydrodinamic, Nozzle, Boiler, CFB, CPFD, Hidrodinamik, Nozzle
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) > TA357 Computational fluid dynamics. Fluid Mechanics T Technology > TD Environmental technology. Sanitary engineering > TD899.S68 Steam power plants T Technology > TJ Mechanical engineering and machinery T Technology > TJ Mechanical engineering and machinery > TJ164 Power plants--Design and construction T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK1001 Production of electric energy or power
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User:	Muhammad Adim Izzulhaqqie
Date Deposited:	15 Aug 2023 01:54
Last Modified:	15 Aug 2023 01:56
URI:	http://repository.its.ac.id/id/eprint/102292

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