Agitation & Mixing

CHAPTER 4: AGITATION AND MIXING PRESENTE PRES ENTED D BY: BY:

NUR SYAZWANI SYAZWANI BINTI BINT I ANUAR NUR NABILAH BINTI KHAIRUL ANUAR RAJA SYAZWINA BINTI RAJA HAFIZ WAZIRR BIN HISHAM NURUL SYAKIRAH SYAKIRAH BINTI BINT I AB RAHMAN

LECTURER’S NAME:

MADAM SALAMIAH BINTI ZAKARIA

Agitation 

It is an induced circularly motion of the material in a container in a desired way.



Material is agitated by a stirrer or mixer that is made up of shaft that connects motor and the impeller.

Mixing 

It is a random distribution of materials in different phases into another phases forming a homogenous phase.

Purposes of Agitation

1. Blending miscible liquids, e.g. methyl alcohol (C2!" and water (2!". #. $romotes heat transfer between the liquid in the tan% or container and a coil or &ac%et surrounding the container. '. ispersing a gas in a liquid as fine bubbles. ). issol*ing solids in liquids. +. uspending of fine solid particles in a liquid.

DESIGN OF AGITATED VESSEL  -gitated *essel had been designed consists of / Motor  / peed reducer  / haft / Impeller  / Baffle / 0ac%et / hermowell ypical agitation *essel

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Round botto s!ape o eliminate corners where fluid cannot penetrate

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Motor  -d&ust the speed of agitation of impeller 

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Speed redu"er  Control the agitation speed

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S!aft - rotating member with impeller mounted on and dri*en by motor which is used for agitation or mixing purpose.

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Ipe##er  Creates a flow pattern

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$aff#e 2educe tangential motion of fluid

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%a"&et Made up of coil and in*ol*e in heat transfer to liquid

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T!ero'e## $rotect the temperature sensing elements (thermocouples" from brea%ing and allow the elements to be remo*e for ser*ice without need to shutdown the process

T(PES OF IMPELLER Pr$%"&&"r

P'((&"#

 Turb!"#

PROPELLER / $ropeller agitators3 blades are commonly attached to the main shaft. Its tapering blade can minimi4e the effect of centrifugal force and produce a maximum axial flow. / hey are flexible in operations and mostly used in mechanical mixing of low to medium *iscosity fluids.

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PADDLES / $addle agitator is a agitator with blades that reach up to the tan% wall. hey are used where an uniform laminar flow of liquids is desired. / uitable for stirring low and middle *iscosity liquids at moderate speeds

T)R$INE / urbine agitator is multi5bladed paddle agitator. It can create a turbulent mo*ement of fluids due to the combination of centrifugal and rotational motion. / urbine has an excellent feature in designing the flow patter where a change in design can di*ert the flow pattern of fluid by radial flow or axial flow in the reactor *essel.

AGITATOR

APPLICATION

MODEL

ADVANTAGE

/ PROPELLER

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DISADVANTAGE

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F#o' Pattern in Agitation Vesse# Can be categori4ed into three  1" -xial 6low  $arallel to the shaft  More energy efficient than radial flow mixing.  More effecti*e at lifting solids from the base of the tan%.  7sed for blending and solids suspension.

#" 2adial 6low  $erpendicular to the shaft.  he currents tra*el outward to the *essel wall and then either upward or downward.  igher energy is required compared to axial flow impellers.  7sed for dispersion

'" angential 8 wirling 6low  angential to the circular path  angential or swirling flow field is ineffecti*e at dispersing the solids (grouped below the impeller".   -t high impeller speeds, *ortex is formed and may be so deep that it reaches the impeller.  he higher the speed , the deeper the *ortex.  9arge surface *ortex is *isible at the top of the shaft.

*o' to pre+ent s'ir#ing in agitation +esse# wo ways to pre*ent swirling  

Installing baffles in tan% Mixer mounting 5!ffset angle mounting of mixers 5!ffset *ertical mounting of mixers

1" Installing baffle in tan% / Is a long, flat plates attached to the side of tan% / Commonly used in cylindrical tan% for blending solid suspension / uitable for large tan%s with *ertical agitators / $romote the mo*ement of fluid from top to bottom

M6"r A/)')$r 9)0 T'!< B' "# + Y$uTub"=MP4

#" Mixer mounting Offset ang#e ounting of ixers

Offset +erti"a# ounting of ixers

/ Impeller is mounted approximately 1:51+ from the *ertical

/ Mixer be offset by being placed *ertically in tan% / he rule is to offset the mixer for 18; th of the total diameter tan%

BRAWN M6"r S1'r)# P'r) * + Y$uTub"=MP4

BRAWN M6"r S1'r)# P'r ) ? + Y$uTub"=MP4

 THE END