@mastersthesis{eprints88429,
           month = {Mei},
           title = {KARAKTERISTIK ALIRAN FLUIDA PADA PEMBAKARAN
BATUBARA-WOODCHIPS DALAM FURNACE CIRCULATING 
FLUIDIZED BED SECARA NUMERIK 
(STUDI KASUS UP SEBALANG) },
          school = {LAMPUNG},
          author = {AZIS MOH.ROSIFAUL },
            year = {2025},
             url = {http://digilib.unila.ac.id/88429/},
        abstract = {Pembangkit Listrik Tenaga Uap (PLTU) berbasis batu bara masih menjadi
tulang punggung penyedia energi listrik di Indonesia, namun menghasilkan emisi
gas rumah kaca yang tinggi. Salah satu solusi untuk mengurangi dampak
lingkungan tersebut adalah melalui teknologi high co-firing, yaitu pencampuran
batubara dengan biomassa seperti woodchips. Meskipun implementasi co-firing
telah dilakukan, masih terdapat keterbatasan dalam pemahaman karakteristik aliran
fluida dan pembakaran dalam furnace secara menyeluruh, khususnya pada sistem
boiler tipe Circulating Fluidized Bed (CFB). 
Penelitian ini bertujuan untuk menganalisis karakteristik aliran fluida dalam
furnace CFB PLTU Sebalang melalui pendekatan simulasi numerik menggunakan
simulasi Computational Fluid Dynamics (CFD) dengan model multiphase
Eulerian, k-{\ensuremath{\epsilon}} turbulence model, serta discrete phase untuk injeksi partikel batu
bara. Simulasi dilakukan untuk tiga variasi bahan bakar: 100\% batu bara, 90\% batu
bara + 10\% woodchips, dan 80\% batu bara + 20\% woodchips. Parameter yang
diamati meliputi distribusi temperatur, tekanan, kecepatan udara, dan fraksi volume
material padat (pasir) di dalam furnace. 
Hasil simulasi menunjukkan bahwa penambahan fraksi woodchips
menurunkan temperatur rata-rata furnace dari 945 ?C menjadi 810 ?C dan tekanan
dari 224 Pa menjadi 88 Pa. Kecepatan aliran udara meningkat dari 4,7 m/s menjadi
7,5 m/s, serta terjadi penurunan fraksi volume pasir di zona dense phase dari 0,703
menjadi 0,655. Meskipun terdapat perbedaan nilai antara hasil simulasi dan data
aktual, tren perubahannya tetap linear dan konsisten. Ketidaksesuaian disebabkan
oleh terbatasnya cakupan simulasi yang tidak mencakup efek induced draft fan dan
area backpass. 
Implikasi dari temuan ini menegaskan bahwa meskipun co-firing dengan
woodchips berpotensi mengurangi emisi dan mendukung transisi energi bersih,
diperlukan pengaturan yang cermat terhadap rasio bahan bakar, distribusi udara,
dan sistem pencampuran agar efisiensi pembakaran dan stabilitas aliran tetap
optimal. Hasil penelitian ini diharapkan dapat menjadi dasar pengembangan strategi
operasional PLTU dalam menerapkan co-firing secara lebih efektif dan
berkelanjutan.

Kata kunci: co-firing, woodchips, Circulating Fluidized Bed, simulasi numerik,  
         fluidisasi. 
Coal-fired power plants remain the backbone of electricity generation in
Indonesia but are major contributors to greenhouse gas emissions. One promising
solution to mitigate these environmental impacts is the implementation of high cofiring

technology, which involves blending coal with biomass such as woodchips.
While co-firing has been applied in practice, there remains a knowledge gap
regarding the comprehensive understanding of fluid flow and combustion
characteristics within the furnace, particularly in Circulating Fluidized Bed (CFB)
boiler systems. 
This study aims to analyze the fluid flow characteristics within the CFB
furnace at PLTU Sebalang through a numerical simulation approach using
Computational Fluid Dynamics (CFD). The simulation employs a multiphase
Eulerian model, a k-{\ensuremath{\epsilon}} turbulence model, and a discrete phase model for coal
particle injection. Simulations were conducted for three fuel compositions: 100\%
coal, 90\% coal + 10\% woodchips, and 80\% coal + 20\% woodchips. The observed
parameters include temperature distribution, pressure, air velocity, and the volume
fraction of solid materials (sand) within the furnace. 
The simulation results indicate that increasing the woodchips fraction
reduces the average furnace temperature from 945 ?C to 810 ?C and the pressure
from 224 Pa to 88 Pa. Airflow velocity increases from 4.7 m/s to 7.5 m/s,
accompanied by a decrease in sand volume fraction in the dense phase zone from
0.703 to 0.655. Although numerical differences exist between the simulation results
and aktual data, the overall trend remains linear and consistent. The discrepancies
are primarily due to the limited scope of the simulation, which does not account for
the effects of the induced draft fan and the backpass area. 
These findings imply that although co-firing with woodchips has the
potential to reduce emissions and support a cleaner energy transition, careful
control of fuel ratio, air distribution, and mixing systems is essential to maintain
combustion efficiency and flow stability. The results of this study may serve as a
reference for optimizing operational strategies in implementing co-firing
technology more effectively and sustainably in coal-fired power plants.

Keywords: co-firing, woodchips, Circulating Fluidized Bed, numerical simulation,  
      fluidization. 
  }
}