AGITATION AND MIXING OF FLUIDS - Cvut.cz
AGITATION AND MIXING OFFLUIDSPurpose of agitation: intensification of transport processes in agitated batch (heat and mass transfer) preparation of materials of required properties (suspension, emulsion)Examples of industrial applications: blending of two miscible liquids as ethyl alcohol and water dissolving solids in liquids, such as salt in water dispersing a gas in a liquid as fine bubbles, such as oxygen fromair in a suspension of microorganisms for fermentation or for theactivated sludge process in waste treatment liquid-liquid dispersion, such as dispersion of pigment in solvents suspending of fine solid particles in a liquid, as in catalytichydrogenation of a liquid agitation of the fluid to increase heat tranfer between the fluid anda coil or jacket in the vessel wall
Method of mixing fluids mechanical mixing (rotating, vibrating) hydraulic mixing pneumatic mixing pipeline mixing (turbulent flow, static mixer)A – mechanical mixing usingturbinesB – mechanical mixing usingblade impellersC – hydraulic mixingD – pneumatic mixing withstationary inputsE – pneumatic mixing withautomatic regulationF – hydraulic mixing withantifoaming shower
Pipeline mixing – Reynolds experimentsPaul, E. L., Atiemo-Obeng, V. A., Kresta, S. M.:Handbook of industrial mixing: science andpractice. Canada: Wiley-Interscience, 2003,1377 p. ISBN 0-471-26919-0
Flow in agitated batcha – axial-flow pattern, baffled vessel, b – radial-flow pattern, baffled vessel,c – tangential-flow pattern, unbaffled vessel
Equipment for mechanical mixingDesign layout of mixing equipmentsABCA – Centrally placed impeller in bafled vessel, B – Side-entring propeller, C – Agitatorwith draught tubeMechanical sealABA – Equipment with a drive at the top, B – Equipment with a drive at the bottom
Design layout of agitatorsClose clearance agitatorHigh-speed impeller
Maine type of close clearance agitatorsNo.Layout of agitatorName1Anchor (paddle)agitatorCVS 69 10142Helical-screw agitatorwith draught tubeCVS 69 10283Eccentrically placedhelical-screw agitatorT/dGeometricalparameters1,11hv / d 0,8h / d 0,12H 2 / d 0,0552hv / d 1,5s/d 1D / d 1,1H / D 1,152hv / d 1,5H 2 / d 0,25s/d 1c / T 0,02
T/dGeometricalparameters4Helical-ribbonagitatorCVS 69 10291,05hv / d 1s/d 1h / d 0,15Leaf agitatorCVS 69 10162h/d 12h / d 0,2hv / d 1,65 45 45 c / T 0,02H 2 / d 0,175No.6Layout of agitatorNameMulti-stage agitator
Main type of high-speed impellersT/dGeometricalparameters1Six-blade turbinewith disk (Ruschtonturbine)CVS 69 10213 4h / d 0,21 / d 0,25d1 / d 0,756 blades2Six-blade openturbine3 4h / d 0,26 blades3Pitched six-bladeturbine with pitchangle 45CVS 69 10203 4h / d 0,20 45 No.Layout of impellerName
No.456Layout of impellerNameT/dGeometricalparametersPitched three-bladeturbine with pitchangle 45 CVS 69 1025.33 4h / d 0,2 45 3 4s/d 1h / d 0,22R / d 0,4R1 / R 0,16PropellerCVS 69 1019High shear stressimpellerCVS 69 1038.1, .22 41st varianth / d 0,1d 2 / d 0,82nd varianth / d 0,075d 2 / d 0,85
Characteristics of mixing systemPower consumption of agitatorPPo n3d 5creepingflowPo f Re transitionzone of flowRe nd 2 turbulentflowPo B const.APo Rebaffledvesselunbaffledvessel
Power characteristics of close clearance agitators1 – anchor agitator (CVS 69 1014), 2 – helical-screw agitator with draught tube (CVS69 1028), 3 – eccentrically placed helical-screw agitator, 4 – helical-ribbon agitator(CVS 69 1029), 5 – leaf agitator (CVS 60 1016), 6 – multi-stage agitator
Power characteristics of high-speed impellers operated in baffled vessel1 – six-blade turbine with disk (Ruschton turbine) (CVS 69 1021), 2 – six-blade openturbine, 3 – pitched six-blade turbine with pitch angle 45 (CVS 69 1020),4 – Pitched three-blade turbine with pitch angle 45 (CVS 69 1025.3), 5 – propeller(CVS 60 1019), 6a,b – high shear stress impeller (CVS 69 1038.1.2)
Blending effect of agitatorDuring homogenization (or blending) of miscible liquids are compensated temperature andconcentration differences in agitated batch.Homogenization of miscible liquids: due to recirculation flow (convective diffusion) due to turbulent flow (turbulent diffusion) due to molecular diffusiont n t m f Re t n t m konst.t n t m konst.
Homogenization characteristics of agitatorst n t m f Re 1 – helical-screw agitator with draught tub (CVS 69 1028), 2 – eccentrically placedhelical-screw agitator, 3 – helical-ribbon agitator (CVS 69 1029), 4 – eccentricallyplaced multi-stage agitator, 5 – anchor agitator (CVS 69 1014), 6 – six-blade turbinewith disk (Ruschton turbine) (CVS 69 1021)
E P tm1 – helical-screw agitator with draught tub (CVS 69 1028), 2 – eccentrically placedhelical-screw agitator, 3 – helical-ribbon agitator (CVS 69 1029), 4 – eccentricallyplaced multi-stage agitator, 5 – anchor agitator (CVS 69 1014), 6 – six-blade turbinewith disk (Ruschton turbine) (CVS 69 1021)
Mixing of heterogenous batchHeterogeneous batch: liquid – gas liquid – liquid (emulsion) liquid – solids (suspension)Purpose of agitation Intensification of mass transferm S A
Dispersion of gas in liquid Flooding of impellerV g d 16,6Fr 3nd T 3, 4 Recommended gas flow-rate VVM 1 1,5(volumetric flow of gas per liquid volume per minute) Size of dispersed bubbles dbe.g. water – air: (P/V) –0,4 0,6 cv0,5 4d b 4,15 0, 2 9 10 P / V 0, 4
Impeller power consumption for gas – liquid dispersing V g f 3 nd P Pg
Dispersion of liquid – liquid systems(preparation of emulsion)Size of dispersed liquid drops balance of dynamic and surface forces35 2 5d 32 c n2d 3 cWe d32 3 5 Wed
Limits of dispergation technology andequipment
Impeller power consumption for liquid – liquid dispersingPPo mix n 3 d 5Po f Re mix cv d 1 cv cRe nd 2 mix mix
Mixing of suspension
Just-suspended impeller speed n2dFr g dp Fr C D C A exp B cv cc Tp/D0,1
Impeller power consumption for mixing of suspensionPPo su n 3d 5Po f Re su cv s 1 cv Re nd 2 su
Scale-up of mixing processes
EXAMPLE: Blending efficiency of impellersSelect type of high-speed impeller with minimum energetic requirementsfor continual blending (homogenization) of two miscible liquids A B ( 5mPa·s, 1100 kg·m-3) with flow rate of mixture 10 l·s-1. For suitable degreeof homogenization must be residence time of liquids in equipment 5 x longerthan blending time. Mixing equipment has standard geometrical configuration(baffled cylindrical vessel with diameter T 1200 mm, T/d 3.3; H2/d 1, H/T 1 ).Dimensionless blending time of high-speed impellers in turbulent flow regimeType of impellerSix-blade turbine with disk (Ruschtonturbine), CVS 69 1021Pitched six-blade turbine with pitchangle 45, CVS 69 1020Pitched three-blade turbine with pitchangle 45 , CVS 69 1025.3T/dH2/dn·tm3.3151.83.3153.13.3160.5
mechanical mixing (rotating, vibrating) hydraulic mixing pneumatic mixing pipeline mixing (turbulent flow, static mixer) Method of mixing fluids A –mechanical mixing using turbines B –mechanical mixing using blade impellers C –hydraulic mixing D –pneumatic mixing with stationary inputs
Agitation, Mixing, and Transfers Induced by Bubbles Frédéric Risso To cite this version: Frédéric Risso. Agitation, Mixing, and Transfers Induced by Bubbles. . Furthermore, the existence of a density difference can lead to another major consequence. A single phase is usually set in motion by an imposed external pressure gradient, caused .
Mixing of fluids with complex rheology is encountered more and more frequently in industries. Nonetheless, mixing behaviour of such fluids is still poorly understood due to the complexity of their rheological behaviour. This study aims to enhance fundamental understanding of the flow and mixing of rheologically complex fluids such as thixotropic,
4 Difference between Standard Agitation System and Smart Agitation System The Standard Agitation System was designed to be used with one of our main systems (AMPTS, Gas Endeavour and Bioreactor Simulator), meaning that the operator of the main equipment can control the motors directly through the software of the main system units.
4 I MIRKA ESSENTIALS PAINT MIXING mirka.com PAINT MIXING SOLUTIONS The Mirka Paint Mixing product range includes mixing cups, lids & systems, mixing sticks, paint strainers, practical dispensers and cloths. Caters for automative refinishing professional paint mixing needs. Size Mirka Code Pcs/pack 180ml 9190170180 50 400ml 9190170400 50
Mixing Newtonian Fluids The ability of the modeling framework given by Eq. 4to capture the mixing of Brownian particles over more than five orders of Péclet number is clearly demonstrated in Fig. 3 A using three different Newtonian fluids (water μ 0.001 Pa·s, 20:80 wt % water:glycerol μ 0.054 Pa·s, and glycerol μ 1.2 Pa·s, Table S1).
2l MIXING IN STRATIFIED FLUIDS 7 D I i Ip2 I '"2 I I I I u, p1 I I I IU OL - I I FIGURE 1.A diagrammatic represemtation of the vertical profiles of density (solid Iine) and velocity (broken fine), before (a) and after (b) a mixing event.It is assumed that after mixing the profiles have the same form, although the thicknesses of the transition regions have been altered.
estimates of functional requirements for the process mixing vessels including vessel geometry, agitation speed, and power consumption are provided. 1.3 OVERVIEW OF MSF REQUIREMENTS For an initial estimation purposes, MSF will be considered to house six, 500,000 gallon tanks, each equipped with equivalent waste mixing and sampling capabilities.
5 I. Academic Writing & Process . 2. 1 Prepare . 2. 1. 1 What is the assignment asking you to do? What kind of assignment is it? (E.g. essay, research report, case study, reflective
