Iswara, Mochammad Agung Indra (2016) Studi Fluidisasi Dan Pembakaran Batubara Polydisperse Di Dalam Fluidized Bed Dengan Pendekatan Numerik Berbasis Simulasi CFD. Masters thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Penelitian ini berupaya untuk memecahkan masalah yang akan dilakukan
melalui studi menggunakan metode simulasi berbasis Computational Fluid
Dynamic(CFD). Sehingga penelitian ini bertujuan untuk mengembangkan penerapan
CFD dan model-model pembakaran dalam proses pembakaran batubara dalam fluidized
bed dengan mempelajari hidrodinamika sistem padat-gas seperti mengamati pola aliran
serta pengaruh laju alir batubara yang baru yang masuk dari samping di dalam fluidized
bed combustion..
Simulasi berbasis CFD yang memperhitungkan jumlah ukuran dan pola alir
fluida secara simultan mampu menyajikan informasi terperinci tentang apa yang terjadi
di dalam fluidized bed combustion. Gambaran rinci mengenai profil ukuran, kecepatan
aliran, konsentrasi di setiap titik di dalam fluidized bed combustion memberikan
alternatif pemecahan masalah untuk mengetahui kondisi fluidisasi pada fluidized bed
combustion.
Langkah-langkah yang dilakukan sebelum melakukan simulasi pembakaran
adalah dengan melakukan validasi fluidisasi, yaitu dengan menggunakan geometri 2-D
fluidized bed lalu dilakukan meshing, selanjutnya dilakukan metode simulasi pembakaran
dengan menggunakan pemodelan UDF.
Geometri fluidized bed combustion yang digunakan berbentuk tabung dengan
panjang silinder fluidized bed combustion 1370 mm, diameter silinder 152 mm. Bahan
yang digunakan pada penelitian ini berupa pulverized coal dengan jenis batubara
Bituminus dimana ukuran partikel dianggap monodisperse dengan particle size sebesar
1.43 mm dan polydisperse dengan ukuran partikel 1 mm dan 1,86mm, dan variasi
kecepatan superficial sebesar 0,1 sampai 1,5 m/s. Metodologi yang dilakukan meliputi
beberapa tahapan diantaranya: membuat model geometri dan grid-nya, menentukan
model, kondisi operasi, kondisi batas, dan parameter.
Kesimpulan yang didapat adalah batubara jenis bituminous memiliki kecepatan
minimum fluidisasi untuk monodisperse sebesar 0,5 m/s selama 10 detik sedangkan untuk
polydisperse hampir sama dengan monodisperse yaitu sebesar 0,45 m/s selama 60 detik.
Sementara pressure drop yang diperoleh untuk monodisperse sebesar 2500 Pa namun
pada polydisperse pressure drop sebesar 1200 Pa. Selanjutnya simulasi pembakaran
dilakukan selama 5 menit, dengan mengacu pada kecepatan bubbling polydisperse yaitu
0,8 m/s simulasi pembakaran berjalan lambat. Massa awal sebesar 34,6 kg dan massa
akhir sebesar 34,25 kg. Pada simulasi pembakaran batubara dibagi menjadi 2 tahap
yaitu devolatilisasi dan pembakaran char, kemudian didapat hasil pembakaran berupa
CO2, CO, tar, dan H2O. Konversi reaksi pembakaran setiap menit mengalami penurunan
dan peningkatan, karena terjadi akumulasi partikel di dalam unggun.
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This research aims to solve the problems that will be done through simulationbased
study using Computational Fluid Dynamic (CFD). Thus, this study aims to develop
the application of CFD models and many models in the process of drying the coal in
fluidized bed drying with studying the hydrodynamics of gas-solid systems such as to
observe the flow pattern and the effect of the flow rate of fresh coal particles which entered
in the side of wall.
CFD-based simulations which calculates the particle size and fluid flow patterns
simultaneously capable to present detailed information about what is happening in the
fluidized bed combustion. A detailed description of the particle distribution profile, flow
velocity, concentration at some points in the fluidized bed combustion provide alternative
solutions to determine the condition fluidization in a fluidized bed combustion.
The steps would be taken before did the combustion simulation was doing the
fluidization validation, that was used a 2-D geometry fluidized bed and then used the
meshing method, the next step is doing the combustion simulation method with UDF
modelling.
The geometry of fluidized bed combustion is used with 1370 mm as the length of
tubular cylindrical fluidized bed combustion is 152 mm. Materials used in this study was
pulverized coal with Bituminous coal type which the particle size was considered as
monodispers with particle size was 1.43 mm and polydispersed with particle size was 1 mm
and 1.86 mm, and the varied of superficial velocity is among 0.1 until 1.5 m/s. The
methodology included several steps, they were: create a model of its geometry and grid,
determine the model, operating conditions, boundary conditions, and parameters.
The conclution was the Bituminous coal had the minimum fluidization of velocity
in the fluidized bed simulation was 0.51 m/s for monodispersed with the pressure drop was
2500 Pa for 10 seconds and 0,45 m/s for polydispersed with the pressure drop was 1200
Pa for 60 seconds. The combustion simulation has done in 5 minutes, which refered to
polydisperse bubbling velocity 0.8 m/s, the simulation of coal combustion ran slowly. The
initial of bed mass was 34,6 kg and the final was 34,25 kg. This simulation was divided by
two step, the first step was devolatilization and the last step was char combustion, and the
result were CO2, CO, tar, and H2O. The conversion of combustion reaction was unstable
in every minutes, because the particles was accumulated in this bed.
| Item Type: | Thesis (Masters) |
|---|---|
| Additional Information: | RTK 620.106 4 Isw s |
| Uncontrolled Keywords: | CFD, batubara, combustion, Fluidized Bed, coal |
| Subjects: | T Technology > TP Chemical technology |
| Divisions: | Faculty of Industrial Technology > Chemical Engineering > 24101-(S2) Master Thesis |
| Depositing User: | Anis Wulandari |
| Date Deposited: | 06 Jul 2017 03:43 |
| Last Modified: | 27 Dec 2018 01:54 |
| URI: | http://repository.its.ac.id/id/eprint/41892 |
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