advanced fluidization engineering

8/11/2019 Advanced Fluidization Engineering

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PRESENTED BY:

PRINCE GEORGE (513CH1070)

DEPARTMENT OF CHEMICAL ENGG

NIT

Advanced

FluidizationEngineeringSeminar



Contents

Minimum Fluidization elocit!

Pressure Dro" in Fluidized #eds

Figure $ DPM simulatio



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-



Bed Trans%ormations

Figure . a/ Fi0ed Bed #/ 1nce"tion o% Fluidization c/ Smoot(l! Fluidized Be

Bu##ling Fluidized Bed



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-



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-



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




(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"; <




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.



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-



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



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



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



TOANH Y)8

advanced fluidization engineering

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