Agitation(Agitacion)
Transcript of 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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