Agitation(Agitacion)

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UNIVERSIDAD POLITECNICA DEL VALLE DE

TOLUCA

UPVT

BIOSEPARATIONS

TEACHER: MARIA ROSA REYES

STUDENT: FRANCISCO SALGADO GONZALEZ

JANUARY-APRIL 2014


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OBJETIVE

The objective of this research is to know about the operation of agitation,restlessness know it's also the types of impellers that exist and are used inindustry, producing flows and parameter to be considered to select the impeller

among other things like the size to be the impeller in a tank.

INTRODUCTION

The agitation process refers to a material movement induced in a particularform, usually with a circulatory pattern in a tank. The operation of agitation isused in the engineering process. For example:

Polymers

Pharmaceutic products

Cosmetics

Food Paints

Chemical products

Waste treatment

The agitation homogenized in terms of concentration and temperatura of theblend. The main purpose of this operation is:

Suspension of solid particles

Miscible liquid blended

Dispersion of a gas in a liquid as small bubbles

Dispersin of a second liquid, inmiscible with the first, to form anemulsion and suspension of tiny drops

The system more used in the industry, corresponds to the liquid/liquid blend.Agitation is a means whereby mixing of phases can be accomplished and bywhich mass and heat transfer can be enhanced between phases or withexternal surfaces. In its most general sense, the process of blending isconcerned with all combinations of phases of which the most frequentlyoccurring ones are:

gases with gases. gases into liquids: dispersion.

gases with granular solids: fluidization, pneumatic, conveying and drying

liquids into gases: spraying and atomization.

iquids with liquids: dissolution, emulsification, dispersion

liquids with granular solids: suspension.

pastes with each other and with solids.

solids with solids: mixing of powders.

lnteraction of gases, liquids, and solids also may take place, as inhydrogenation of liquids in the presence of a slurried solid catalyst where the

gas must be dispersed as bubbles and the solid particles must be kept insuspension.


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CLASIFICATION OF THE IMPELLERS OR AGITATORS

a) Three propeller blades or marine propeller

Axial flow: obtain mximum turbulence

Is used at high speeds

Multiple versin for different aplication: heat exchange, blended,dispersion, suspension, and reaction

Aplicable for viscous fluids up to 400 cp.

Rarely overpassed the 18 inches in diameter

b) Turbine flat sheets

Radial flow: flow hits the walls

Versatile: simple design

Fluids up to 105 cp

Behavoir is the most predictable of the impellers

c) Turbine disks and blades

Axial and radial flows

The disk has a stabilizing effect

Is found wiht curved leaves

Cover the 30-50% of the diameter in the tank

d) Turibine blades inclined

Combined axial flow with radial flow

Is useful to improve the heat transference with the walls and coil

e) Curved turbin blades

Is useful for dispersing fibrous material

f) Turbine housing

Strong radial flow

Special to emulsion and dispersion

g) Impeller serrated

Propeller type

Aplication in emulsion and dispersion

Produces a local effect: dont need baffles

h) Cage blender

Normally goes with an impeller

Cut and beat

i) Anchor paddle

Conforms to the contours of the tank

Cover the 50-80%of the tank

Promote a good heat transference with the walls


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j) Gate paddle

is a paddle type

low speeds

is useful in broad tanks

is for viscous flows and required a shear stress

k) The shaft and hollow impeller

Is useful at high speeds to gas dispersion

l) Propeller with heating

Is for very viscous fluids

Directly move the fluid

It can use with low Re (Reynolds)


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REPRESENTATIVE KINDS OF IMPELLERS


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The impellers before mentioned it can be clasified in axial flow and radial flow.

AGITATOR FLOW PATTERNS

a) Axial or radial impeller without bafles produce vortexesb) Offcenter location reduces the vortexc) Axial impeller with baflesd) Radial impeller with bafles

AGITATOR SELECTION AND SCALE UP AGITATOR

SELECTION

Depends on the viscosity of the liquid

For specific time of mixing, the best mixer is the one that mixes in therequired time with the smallest amount of power

SCALE UP

Maintaining constant power per unit volume and geometric similarity

The three main types are: impelleres, propellers and turbines. These types

cover the 95% in the agitation.


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The Reynolds number describes the turbulence of the flow, in agitation it hasthree kind of flows:

Laminate Transition

Turbulent

The number of power is calculated when the fluid in agitation is aerial, thepower consumed by the impeller decrease, in the case of the newtonian fluids,the power downfall its relationated with the aeration, this power decreasebecause with the aeration form cavities behind the paddles of the impeller.

The power in the impeller is affected with the viscosity, when the liquid in thetank is most viscous the number of power decrease and the impeller needs

more power to agitate the blend. The combination of impellers help theagitation, in this combination the first impeller consumed low power, the function

is the gas dispersion and the othersimpeller transmit more power in the fluid.

MEASUREMENTS OF TURBINE

H: tank height

Da: impeller diameter (1/2*Dt)

Dt: tank diameter

J: baffles

E: height of the impeller to the tank

bottom

Hb: paddle height

Wi: paddle widht

IMPELLER SIZE

This depends on the kind of impeller and operating conditions described by theReynolds, Froude, and Power numbers as well as individual characteristicswhose effects have been correlated. For the popular turbine impeller, the ratioof diameters of impeller and vessel falls in the range, d/D,=0.3-0.6, the lowervalues at high rpm, in gas dispersion.


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CONCLUSION

The conclusin for this research is the operation of agitation has many things toconsider, one of this things is the mesureaments of the impeller in the tank, thepropierties of the liquid and the fluid that is considered, this propiertis are: theviscosity, the density, the number of aeration, the power on the impellers, andthe most important thing is the impeller type that is used in the process and theflow that produce. The result of the example, in the ballon of 500 mL theconclusion is that a high speed of agitation, the power in the ballon it will bemajor.


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BIBLIOGRAPHY

The bibliography used in this research was:

Recovered from fundamentos de operaciones unitarias the autor isClaudio Gelmi Weston from Dpto. de ingeniera qumica y bioprocesos,Pontifica Universidad Catolica de Chile on Monday 10 the February,2014.

Recovered from fermentadores: operaciones de transferencia the autoris Enrique Galindo from Dpto. de Bioingeniera. Instituto debiotecnologa, Universidad Nacional Autonoma de Mxico, Mxico.


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Agitation(Agitacion)

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