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1)Suspension:
Heterogeneous Miture containing
solid particles that are su!!icientl"
large !or sedi#entation$%
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&articles:
Larger then 1 but less then 10 micron.Particles are visible under a microscope.Settle over time if left undisturbed.
Can be separated through a filter.Surface area exposed to fluid is constant.
&urpose:
Increase surface area, ate of dissolution.
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'#peller:
!xial"flo# impellers are used forsuspension.
$hree blade #ith s%uare pitch and four
blade #ith &'degree are common.
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'#peller Speed:
Sli# is carrie# up$ar# b% mil# stirring& ntt 'rm pile at bttm
(cal up$ar# )elcit% is greater thenterminal settling )elcit% ' particals*
ritical '#peller Speed:Critical +,ust-suspen#e# impeller spee# nc*
n particle remains lnger than 1 sec n the
)essel bttm*
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States o! Suspension:
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$o dissolve the solids
$o catal()e a chemical reaction
$o promote the gro#th of cr(stal from
a super saturated solution
'n he#ical &rocessing%%
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2)Dispersion:
Heterogeneous Miture in *hich
dispersed phase is uni!or#l" distri+utedin continuu# phase%$
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&articles:
Si)e of particle 0.01*' micron. Settle do#n if not disturbed but ver( little. !t high shear rate particles are bro+en,
diameter reduces and ne# surface are is
created. -ermentation Li%uid"li%uid/rops and gas"li%uidubbles
total interfacial area b# dispersed and
continuous material ma( var( according to
conditionand degree of Mixing.(Mean
diameter).
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'#peller:adial and axial flo# t(pe impellers.
$hat provide some of both shearturbulence and movement.
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)Blending:
Ho#ogeneous Miture o! t*o Misci+le
i.uids to !or# a single li.uid *ith no
/ariation in concentration !ro# point to
point$%
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i.uids:7niformit( at drop scale is re%uired.
$he li%uid is #ell mixed close to the impeller
/ue to the intense turbulence.
Large radial mixing but small mixing along the
flo#.
!t last li%uid returns to e(e of impeller foragain vigorous mixing.
889 mixing complete in ' circulations.
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'#peller:Small tan+"""Propeller,
:igh ;fficienc( Impeller
center mounted
Large tan+""""Side
;ntering Propeller or
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Static Mier:
:elical"element mixer
>ortex =ixer
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For lo* /iscosit":lending is done b( turbulence in #hich eddies
are formed #hich helps mixing
For high /iscosit":$he flo# is mostl( laminar
lending is done b( repeatedl( dragging a la(er
of one fluid through another.e.g.:and mixing of paint.
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'n he#ical &rocessing%%
In the manufacturing of perfume, blending is
re%uired to dilute the concentrated perfume oils
b( dissolving them in ethanol.Pharmaceutical, in?ection, s(ringeabilit(, pourse
level mixing.
2asoline re%uires uniformit( up to 1mm si)edrop variation in this causes @noc+ing.
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Char\product
Suspension Dispersion Blending
Purpose $urbidit( 7niformit( :omogeneit(
Si)e ofparticles
1 to 10 um 0.01*' um Less then0.01 um
Impellerused
!xial -lo# adial as #ellas !xial -lo#
-lat blade adial-lo#
/egree ofmixing
>er( small Small Large
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