Advanced Fluidization Engineering
Transcript of Advanced Fluidization Engineering
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PRESENTED BY:
PRINCE GEORGE (513CH1070)
DEPARTMENT OF CHEMICAL ENGG
NIT
Advanced
FluidizationEngineeringSeminar
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Contents
Minimum Fluidization elocit!
Pressure Dro" in Fluidized #eds
Figure $ DPM simulatio
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Fluidization
Fluidization is t(e )"eration #! *(ic( solid "articles are trans%orme'uid&li+e state t(roug( sus"ension in gas or li,uid-
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Bed Trans%ormations
Figure . a/ Fi0ed Bed #/ 1nce"tion o% Fluidization c/ Smoot(l! Fluidized Be
Bu##ling Fluidized Bed
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Bed Trans%ormations & E0"lai
From Figure . 2c/31% t(e gas velocit! is increased still %urt(er3 e0"a#ed *ill continue to occur7 t(e solid "articles *ill #ecome
se"arated %rom eac( ot(er and #egin move around in a restle
T(e gross 'o* insta#ilities are cancelled out or dam"ed3 Suc( condi
smoot(l! Fluidized Bed-
1ncreasing t(e velocit! 5ust a slig(t amount %urt(er causes insta
some o% t(e gas starts #!"assing t(e rest o% t(e #ed in t(
#u##les-
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Bed Trans%ormations & E0"lai
1ncidentall! %rom Figure . 2d/ 3 t(e solids in t(e #ed #egin movido*n*ard3 and around in a (ig(l! agitated %as(ion a""ea
#oiling %rot(ing mi0ture-
6it( "art o% t(e gas #u##ling t(roug( t(e #ed and t(e so
moved around as t(oug( t(e! *ere "art o% t(e 'uid3 1t is in
aggregative3 non&"articulate3 or #u##ling 'uidization-
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Minimum Fluidization elocit28m% /
T(is relations(i" is a conse,uence o% t(e %act t(at t(e mass o% t(eoccu"ied solel! #! t(e solid "articles is t(e same no matter *(at
"orosit! o% t(e #ed-
T(e drag %orce e0ceeds t(e gravitational %orce3 t(e "articles #egin
t(e #ed e0"ands 3 t(us increasing t(e #ed "orosit!-
T(is increase in #ed "orosit! decreases t(e overall drag until it is ag
#alanced #! t(e total gravitational %orce e0erted on t(e solid "article
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Minimum Fluidization elocit28m% /
(Pressure drop aross !ed)"(Cross se#$o%a& area o' Tu!e) (o&u*
,o&$d Fra#$o% " ,pe$- .e$/#)
Finall! to
Ergun E,uation: 49D";
At "oint o% Minimum Fluidization 36eig(t o% Bed e,uals Pressure dro" acros
49D"; <
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Minimum Fluidization elocit28m% /
For Rep 20 Case 'or s*a&& par#$&es
/
For Rep 1000 Case 'or 4er &ar/e par#$&es
/
For /e%era& Case 'or Iso#rop$ saped ,o&$ds
Measured values o% 9s range %rom >-? to $3 *it( >-@ #eing a normal val
granular solid-
Ar$*edes %u*!er 2
determine t(e motion
to densit! dierences-
a dimensionless num#er
ratio o% gravitational %or
%orces-
g/g4.
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oid %raction at MinimumFluidization 2m% /
Measured values o% mf
*(en t(e "articles in t(e 'uidized #ed are %airl! s#e calculated #! correlation t(at a""arentl! gives ,uite accurate "redict
*it(in $>-
Anot(er commonl! used correlation is o% 6en Yu-
For large "articles 3 t(e "redicted mf can #e muc( too small- 1% a value o>-> is "redicted3 it s(ould #e considered sus"ect- alues o% mf around >t!"ical-
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Minimum Fluidization elocit!28m% / Cont- For u%6%o% 4a&ues o' a%d 8
mf
can #e re*ritten as
For *ide range o% values %rom >->>$ & >>> *it( 8mf values *it( stao% G;-
Solving t(e a#ove e,uation
For Coarse "articles
C(itester et al-
For Fine "articles
6en Yu-
From Hunii and Ievens"iel Fluidizatio
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Pressure Dro" in Fluidized #e
From Hunii and Ievens"iel3 FluidizatioRo#ert E- Hrieger3 Pu#lis(ing Co- $JK"u#lis(ers-
A + C
F$/ure 3 9 E:e# o' Gas 4e&o$# o% Pressure
drop $% F&u$d$;ed +eds
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Pressure Dro" in Fluidized #e&E0"lained Till region A 3relative lo* 'o* rates in Fi0ed #ed "ressure dro" is a""ro0-
to gas velocit! reac(ing LPma0 *(ic( is slig(tl! (ig(er t(an Static #ed "re
)n Furt(er increase in gas velocit! voidage increases %rom to m% result
decrease in "ressure dro" to static #ed "ressure-
1n region B3 t(e "ressure dro" remains constant as t(ere is no %urt(er c(a
as t(ere is no esca"ing o% #ed materials-
6it( %urt(er increase in gas velocit! esca"ing o% #ed materials occurs de
initiation o% entrainment in Figure ; at "oint C *it( condition7 LP<6eig(
"articles in Fluidized Bed4Area o% cross section o% tu#e-
A
+
C
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TOANH Y)8