filosofi cfb boiler : pengertian dasar dan aplikasi

pengertian dasar fluidisasi

1. “FILOSOPI CFB BOILER”

2. Fluidisasi didefinisikan sebagai suatu operasi dimana
hamparan zat padat diperlakukan seperti fluida yang
ada dalam keadaan berhubungan dengan gas atau
cairan
KONSEP DASAR “FLUDISASI”
Jika hamparan itu dimiringkan, permukaan atasnya
akan tetap horizontal dan benda-benda besar akan
mengapung atau tenggelam di dalam hamparan itu
tergantung pada perbandingan densitas dari partikel
tersebut.
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3. Kecepatan aliran gas
Fixed bed
Pnematic
transport
Circulating
fluidized bed
Bubbling
fluidized bed
FENOMENA FLUDISASI
Abu
/char
Klasifikasi GELDART

4. Klasifikasi GELDART dan karakteristiknya
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5. Increasing Gas Velocity
Fixed
Bed
Particulate
Regime
Bubbling
Regime
Slug Flow
Regime
Turbulent
Regime
Fast
Fluidization
Pneumatic
Conveying
Gas
Solids Return
Solids Return
Solids Return
U
ch
U
U
mfU
mb
U
REZIM FLUIDISASI
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6. REZIM
FLUIDISASI
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7. Pressuredrop
vs.velocity:
fixed
fluidisedbed
HUBUNGAN ANTARA KECEPATAN FLUIDISASI DENGAN
PENURUNAN TEKANAN DAN KETINGGIAN HAMPARAN

8. Bed Pressure Bed pressure is an one of importance
parameterthateffect on boilerefficiency
and reliability.
Measured abovegrid nozzle about 20 cm.
Pb
Pw
FI

9. Bed Pressure
•
Effect of low bed pressure
-
-
-
-
poor heat transfer
boiler responds
high bed temperature
damage of air nozzleand refractory
•
Effect of high bed pressure
-
-
-
increase heat transfer
more efficient sulfur capture more
power consumption of fan

10. Bed Pressure
•
Cause of low bedpressure
-loss of bedmaterial
-toofineof bed
materials
-high bedtemperature
•
Cause of high bedpressure
-
-
agglomeration
toocoarseof bed material

11. Fluidisation:
effectofgas
distributor
type
HUBUNGAN ANTARA TIPE PLAT DISTRIBUTOR TERHADAP FLUIDISASI

12. Behaviorofbubblesjustabovethedistributor
Porous
plate
Perforated
plate
Nozzle-type
tuyere
Bubble cap
tuyere
HUBUNGAN ANTARA TIPE PLAT DISTRIBUTOR
TERHADAP FLUIDISASI

13. TheKunii-Levenspielmodel
2
Gasflow=
gasflowviaemulsion
+ gasflowviabubbles
mf
i.e.,withbedareaA,
andsuperficialvelocityu
o:
ss,up s,down
flow(u
o-u
mf)*Aviabubbles
u
bu
mf
flowu
mf
*A
viaemulsion
u
bu
mf
1
Risevelocityof bubbles:u
b 0.711(gd
b)
u
mf
Risevelocityof emulsionphase:u
e 

Superficialrisevelocityof emulsiongas: u
mf
Risevelocityof solids:u u u 0
u
0u
mf
Fractionof bedinbubbles:


u
b
u
0
Fraction of emulsion in bed
1-δ=
BEBERAPA MODEL PERSAMAAN KECEPATAN

14. Circulation
•
Circulationis particular
phenomena of CFBboiler.
•
Bedmaterial andfuel are
collectedat cyclone
separator
•
Returntothe furnacevia
loop seal
•
HP blowersupplyHPair to
collectedmaterials to fluidize
returntofurnace

15. Circulation
•
Effect of malfunction circulation
-
-
-
-
No circulation result in forced shut down
high rate of circulation
high circulation rate need more power ofblower
lowrate ofcirculation

16. Circulation
•
Cause of malfunction circulation
-
-
-
-
insufficiencyair flow toloop sealnozzle
insufficient
pluggingof
air pressure toloop seal
HPblower inlet filter
blocking orplugging ofloopsealnozzle