Analisa Numerik Pengaruh Penyusunan Refractory Beam Terhadap Aliran Multifasa Fluidisasi Pada Cfb Boiler Dengan Metode Computational Particle Fluid Dynamics (CPFD)

Firnanda, Mochammad Fadhel (2023) Analisa Numerik Pengaruh Penyusunan Refractory Beam Terhadap Aliran Multifasa Fluidisasi Pada Cfb Boiler Dengan Metode Computational Particle Fluid Dynamics (CPFD). Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Circulating Fluidized Bed (CFB) Boiler sendiri merupakan generasi selanjutnya dari fluidized bed boiler setelah bubbling bed yang bekerja dengan memanfaatkan kondisi hidrodinamik yang spesial dikenal dengan fast bed. CFB boiler memiliki beberapa kelebihan seperti fleksibilitas bahan bakar dan efisiensi pembakaran yang lebih tinggi. Namun sayangnya, kekurangan CFB boiler terletak potensi erosi yang tinggi pada dinding furnace dan cyclone separator akibat tumbukan partikel pasir sepanjang kondisi operasi. Salah satu faktor yang mempengaruhi laju erosi adalah pada kondisi hidrodinamika pada CFB boiler, dimana hal ini dapat dipengaruhi mulai oleh banyak hal salah satunya adalah penyusunan jumlah dan posisi dari refractory beam. Diperlukan penelitian untuk mengetahui pengaruh jumlah dan posisi refractory beam terhadap fenomena hidrodinamika fluidisasi pada CFB boiler PLTU X dengan kapasitas 100 MW pada kondisi operasi rasio PA/SA sebesar 60/40. Penelitian ini dilakukan dengan metode pendekatan numerik Computational Particle Fluid Dynamic (CPFD) menggunakan bantuan perangkat lunak CPFD Barracuda Virtual Reactor 17.4. Simulasi dilakukan dengan empat konfigurasi jumlah dan jarak refractory beam. Pemodelan aliran gas-padat dilakukan dengan pendekatan Eulerian-Lagrangian, model turbulen Large Eddy Simulation, model drag WenYu-Ergun, kondisi transien, dan dengan reaksi pembakaran. Hasil penelitian ini yaitu distribusi fraksi volume partikel, tekanan, kecepatan vertikal partikel, temperature, heat transfer serta potensi erosi. Hasil simulasi menunjukkan bahwa penyusunan refractory beam dari segi jumlah dan posisi berpengaruh terhadap aliran multifasa pada furnace CFB boiler. Dari hidrodinamika, terdapat peningkatan fraksi volume partikel secara signifikan pada area dinding (annular zone) untuk kasus penggunaan refractory beam dengan jumlah 5 dan 3 berjarak 4m jika dibandingkan dengan kondisi eksisting. Sedangkan penggunaan 7 refractory dengan jarak 2m mengalami penurunan akumulasi fraksi volume partikel. Sedangkan pada daerah tengah boiler (core zone), tidak teradapat perbedaan signifikan terhadap perubahan penyusunan refractory. Hal ini juga berakibat pada pressure drop di sepanjang furnace yang serupa antara konfigurasi satu sama lain. Untuk kecepatan vertikal partikel, penggunaan refractory beam mengakibatkan adanya vortex flow sehingga tercapai kecepatan vertikal partikel ke atas maksimum pada tengah boiler terjadi pada daerah dekat dengan posisi refractory teratas di masing-masing konfigurasi. Dari segi perpindahan panas, penggunaan 5 refractory mengalami peningkatan penyerapan panas sebesar 24.55 MW atau setara 23.74%, 3 refractory peningkatan sebesar 32,82 MW atau setara 32.82%, dan 7 refractory berjarak 2m sebesar 8.43 MW atau setara 8.15% dibandingkan kondisi eksisting. Dari segi laju erosi, pengurangan jumlah serta posisi refractory teratas yang lebih rendah berakibat pada peningkatan potensi erosi pada walltube ketinggian 14-39m, sedangkan peningkatan jumlah refractory memiliki potensi erosi pada walltube ketinggian 8-14m yang lebih rendah.
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The Circulating Fluidized Bed (CFB) Boiler itself is the next generation of fluidized bed boiler after the bubbling bed, which operates by utilizing a special hydrodynamic condition known as the fast bed. CFB boiler has several advantages, such as fuel flexibility and higher combustion efficiency. However, it has a downside, which is the potential for high erosion on the furnace walls and cyclone separator due to the collision of sand particles during operation. One of the factors influencing the erosion rate is the hydrodynamic condition in the CFB boiler, which can be influenced by various factors, including the arrangement such as quantity and position of refractory beams. Research is needed to understand the effect of the quantity and position of refractory beams on the hydrodynamic phenomena of fluidization in the 100 MW capacity CFB boiler at Power Plant X, operating under the conditions of a 60/40 primary air to secondary air ratio. This research was conducted using the Computational Particle Fluid Dynamic (CPFD) numerical approach, employing the CPFD Barracuda Virtual Reactor 17.4 software. The simulation was carried out with four configurations of refractory beam quantity and spacing. The modeling of the gas-solid flow was performed using the Eulerian-Lagrangian approach, the Large Eddy Simulation turbulence model, the WenYu-Ergun drag model, transient conditions, and combustion reactions. The results of this research include analysis of the distribution of particle volume fraction, pressure drop, vertical particle velocity, temperature, , heat transfer, and erosion potential. The simulation results show that the arrangement of refractory beams, in terms of quantity and position, significantly affects the multiphase flow in the CFB boiler's furnace. From the hydrodynamic perspective, there is a significant increase in particle volume fraction in the annular zone (wall area) when using 5 and 3 refractory beams spaced 4m apart compared to the existing condition. However, when using 7 refractory beams spaced 2m apart, there is a decrease in particle volume fraction accumulation. In the core zone (middle area) of the boiler, there is no significant difference in the change of refractory arrangement, resulting in similar pressure drops along the furnace for all configurations. Regarding the vertical particle velocity, the use of refractory beams creates vortex flow, leading to the maximum upward particle velocity in the middle of the boiler near the topmost refractory position in each configuration. In terms of heat transfer, using 5 refractory beams results in a 24.55 MW increase in heat absorption (equivalent to 23.74%), 3 refractory beams lead to a 32.82 MW increase (equivalent to 32.82%), and 7 refractory beams spaced 2m apart result in an 8.43 MW increase (equivalent to 8.15%) compared to the existing condition. Regarding erosion rate, reducing the number of refractory beams and placing them lower leads to increased erosion potential on the wall tubes at heights between 14-39m. On the other hand, increasing the number of refractory beams results in higher erosion potential on the wall tubes at heights between 8-14m.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	CFB boiler, CPFD, Hydrodynamic, Erosion Potential, Refractory Beam, CFB boiler, Hidrodinamik, Potensi Erosi
Subjects:	T Technology > TJ Mechanical engineering and machinery T Technology > TJ Mechanical engineering and machinery > TJ263.5 Boilers (general)
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User:	Firnanda Mochammad Fadhel
Date Deposited:	10 Oct 2023 05:32
Last Modified:	10 Oct 2023 05:32
URI:	http://repository.its.ac.id/id/eprint/102854

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