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Step 1............................................................... Identification of the type of mixing to perform Step 2................................................. Inventory of the characteristics of mixing materials Step 3............................................. Identification of the global characteristics of mixing rotors Step 4.....................................................................Choice of the rotors Step 5................................................... Calculation of the various mixing parameters (tank – rotors)
DESIGNING A MIXER PAGE PAGEPAGE PAGE 1 11 1/ // /12 1212 12 ZI Nord - 85607 MONTAIGU Cedex - France Tel: 33 (0)2 51 45 35 35 – Fax: 33 (0)2 51 06 40 84 http:\www.rayneri.fr - E-mail : comm-rayneri@vmi.fr PRE PREPRE PRELIMINARY LIMINARYLIMINARY LIMINARY Deciding on and choosing the size of a type of a mixer consists in finding the optimum parameters for the implementation of the desired procedure. Frequently, optimization is limited by constraints such as costs, bulk or physical limits. This approach consists in choosing a certain number of parameters: • Type of agitators and position - Radial discharge rotors - Axial discharge rotors - Mix discharge rotors - Angled discharge rotors - Dispersion/emulsification rotors • Geometry of the tank (size, shape) • Rotation of the rotor (speed, rate of discharge) • Length of mixing • Imposed physical conditions (pressure, temperature) The people who make these choices rely on their knowledge and experience to make them and choices become additionally complex because of a certain number of factors of which the most frequent follow: • The nature and rheology of products can lead to complicated expressions of a certain number of parameters and specifically of their respective progress during the mixing process. More precisely in the case of non Newtonian liquids (when viscosity of liquids is directly related to the speed of shearing) for which is observed non linear progress of the required power and the rate of flow of circulation in respect to the rotation speed of the agitator. This is observed in rheoliquidifying liquids (fruit juice, blood), threshold or Bingham liquids (paint, varnish, mayonnaise, toothpaste), rheothickening liquids (wet grit, starch suspension, pizza dough) or thixotropic liquids (yogurt). • Constraints regarding some parameters because of experience or technologic and economic reasons, such as the peripheral speed return from one type of mixer to another, shearing rate, speed of flow or pumping limit the margin of action for the calculation of the other mixing parameters. It is a limiting factor but we must consider that these constraints, in the end, lead to a more rapid result by minimizing choices. In practice, choosing an agitator becomes a compromise In practice, choosing an agitator becomes a compromiseIn practice, choosing an agitator becomes a compromise In practice, choosing an agitator becomes a compromise: :: : a aa a dominant parameter is dominant parameter isdominant parameter is dominant parameter is established establishedestablished established and calcul and calcul and calcul and calculated and ated and ated and ated and then thenthen then the other parameters the other parameters the other parameters the other parameters are checked to insure they are checked to insure they are checked to insure they are checked to insure they are sufficient are sufficientare sufficient are sufficient. . VMI recommends and implements the following method: Step StepStep Step 1 1 1 1 .Identification of the type of mixing to perform Step StepStep Step 2 2 2 2 . . Inventory of the characteristics of mixing materials Step StepStep Step 3 3 3 3 . Identification of the global characteristics of mixing rotors Step StepStep Step 4 4 4 4 .Choice of the rotors Step StepStep Step 5 5 5 5 . Calculation of the various mixing parameters (tank – rotors) DESIGNING A MIXER PAGE PAGEPAGE PAGE 2 22 2/ // /12 1212 12 ZI Nord - 85607 MONTAIGU Cedex - France Tel: 33 (0)2 51 45 35 35 – Fax: 33 (0)2 51 06 40 84 http:\www.rayneri.fr - E-mail : comm-rayneri@vmi.fr STEP STEPSTEP STEP 1: 1:1: 1: Identification Identification Identification Identification of the type of mixing to perform of the type of mixing to performof the type of mixing to perform of the type of mixing to perform • S SS Solid / liquid olid / liquidolid / liquid olid / liquid mixtures mixturesmixtures mixtures - Soluble powders S oluble powders Soluble powders Soluble powders Dissolution Homogenizing - Non soluble Non soluble Non soluble Non soluble powder powderpowder powders ss s Placing in and/or maintaining in suspension Homogenizing Dispersion • Liquid LiquidLiquid Liquid / l / l / l / liquid iquidiquid iquid mixtures mixtures mixtures mixtures - Miscible liquid Miscible liquidMiscible liquid Miscible liquids ss s Placing in and/or maintaining in suspension Homogenizing Dilution - Immiscible liquids Immiscible liquidsImmiscible liquids Immiscible liquids Emulsion • Complex rhe Complex rheComplex rhe Complex rheol olol olo oo ogy of viscous mixtures gy of viscous mixturesgy of viscous mixtures gy of viscous mixtures Placing in and/or maintaining in suspension Dissolution Homogenizing Dispersion Heat transfer Grinding STEP STEPSTEP STEP 2: 2: 2: 2: Inventory of the characteristics of mixing materials Inventory of the characteristics of mixing materialsInventory of the characteristics of mixing materials Inventory of the characteristics of mixing materials • Liquid LiquidLiquid Liquids ss s - Density - Viscosity - Percentage - Initial and final temperature - Type of discharge • Solid SolidSolid Solids ss s - Nature - Percentage - Density - Granulometric dimensions and distribution - Settling speed - Wettability - Solubility • Ga GaGa Gas ss s - Nature - Flow - Pressure - Solubility STEP STEPSTEP STEP 3: 3:3: 3: Identifi Identifi Identifi Identification of the g cation of the gcation of the g cation of the global loballobal lobal c c c characteristic haracteristicharacteristic haracteristics ss s of mixing of mixingof mixing of mixing rotor rotorrotor rotors ss s • Flow mainly generated (axial or radial) • Importance of the pumping effect (high, medium, low) • Importance of the shearing effect (high, medium, low) • Capacity of generating turbulence (high, medium, low) DESIGNING A MIXER PAGE PAGEPAGE PAGE 3 33 3/ // /12 1212 12 ZI Nord - 85607 MONTAIGU Cedex - France Tel: 33 (0)2 51 45 35 35 – Fax: 33 (0)2 51 06 40 84 http:\www.rayneri.fr - E-mail : comm-rayneri@vmi.fr STEP STEPSTEP STEP 4: 4:4: 4: Choice ChoiceChoice Choice of of of of rotor rotorrotor rotors ss s You must then chose between the varieties of rotors offered by VMI the one that is the best adapted to the mixture you want to produce. Your choice should be based on the following: • Intrinsic characteristics of the rotors taking into account the preferred type of flow, knowing that frequently a compromise must be made between the type of discharge (axial, radial, turbulent…) and mechanical effect generated (circulation, shearing, …), • Laboratory tests, • Financial criteria: example = choice in order to achieve the best Nq/Np performance to minimize installed capacity, • Functional criteria: example = choice of a rotor that is the easiest to clean. Currently VMI offers the following agitation rotors: 1. Profiled triblade 7. Centripetal 13. Break=up 2. Two way profiled triblade 8. Deflocculator 14. Butterfly 3. PSVB four blade 9. Sevin with inlets 15. Saw teeth 4. PSVH four blade 10. Centrifugal 16. Anchor blade 5. PA four blade 11. Centri=deflocculator 17. Rotor=stator 6. Water propeller 12. Cutting DESIGNING A MIXER PAGE PAGEPAGE PAGE 4 44 4/ // /12 1212 12 ZI Nord - 85607 MONTAIGU Cedex - France Tel: 33 (0)2 51 45 35 35 – Fax: 33 (0)2 51 06 40 84 http:\www.rayneri.fr - E-mail : comm-rayneri@vmi.fr Table I Main Flow Main FlowMain Flow Main Flow Rotor RotorRotor Rotor Type Type Type Type Main MainMain Main Fu FuFu Function nctionnction nction Power Power Power Power N NN N P PP P Pumping Pumping Pumping Pumping N NN N Q QQ Q Shearing Shearing Shearing Shearing Strength S trengthStrength Strength Water propeller (6) Circulation 0.21 to 0.28 0.58 to 0.68 Very low Profiled triblade (1) Homogenizing liquid/liquid 0.34 to 0.60 0.84 to 0.87 Very low Two way profiled triblade (2) Dissolution, incorporation charges 0.76 to 1.22 1.15 to 1.2 Very low PSVB four blade (3) Dilution/Dissolution 1 to 1.95 1 to 1.73 Very low PA four blade (5) Dilution/Dissolution 1.8 to 2.2 1 to 1.73 Very low A XIAL AXIALAXIAL A XIAL SEVIN with inlets (9) Dissolution/Dispersion 0.4 to 0.55 0.75 to 0.85 Medium Centripetal (7) Dilution/Dissolution 1.6 to 2 1.1 to 1.3 Low Centrifugal (10) Dissolution 2.5 to 4.5 3 to 3.8 Medium Saw teeth (15) Dispersion 0.23 to 0.42 0.19 to 0.31 High Deflocculator (8) Dispersion 0.34 to 0.8 0.37 to 0.44 High Centri=deflocculator (11) Dispersion 1.1 to 2 0.67 to 0.79 High Rotor/Stator wide slots (17a) Dispersion/Emulsion 2.1 to 5.9 0.82 to 0.9 Very high RADIAL RADIALRADIAL RADIAL Rotor/Stator narrow slots (17b) Dispersion/Emulsion 2.3 to 6.2 0.55 to 0.6 Very high Note: N P , N Q and shearing strength are expressed for equivalent diameters • Power: 53 dN P N p = (P: agitation power; : density; N: rotation speed; d: rotor diameter) is the coefficient of drag from the agitator when in the liquid and represents power usage. • Pumping: 3 dN Q N P Q = (Q P : pumping flow rate; N: rotation speed; d: rotor diameter) is the dimensionless expression of the pumping flow rate for the agitator. • Shearing strength indicates the capacity of the rotor in breaking the friction effect exerted by two infinitesimal layers of liquid sliding against one another. Shearing is usually stated as speed of shearing e V = & , expressed as s =1 , a value that is very difficult to measure. PERFORMANCE MOBILES MARINE TRIPALE BI- DIRECTTIONNELLE QUADRIPALE SEVIN DEFLOCULEUSE CENTRIFUGE TRIPALE PROFILEE ROTOR/ STATOR FL ROTOR STATOR FE CENTRIPETE 0 0,5 1 1,5 2 2,5 3 3,5 Pouvoir de cisaillement RendementdedébitNq/Np M AINTIEN EN SUSPENSION HOMOGENEISATION D ILUTION DISSOLUTION DISSOLUTION DISPERSION D ISPERSION EMULSION Très Faible Faible Moyen Fort Très Fort ROTOR PERFORMANCE Shearing Strength Very Low Low Medium High Very High DESIGNING A MIXER PAGE PAGEPAGE PAGE 5 55 5/ // /12 1212 12 ZI Nord - 85607 MONTAIGU Cedex - France Tel: 33 (0)2 51 45 35 35 – Fax: 33 (0)2 51 06 40 84 http:\www.rayneri.fr - E-mail : comm-rayneri@vmi.fr Table II Solid / Liquid Mixtures Liquid / Liquid Mixtures Soluble Powders Non Soluble Powders Miscible Liquids Immiscible Liquids Complex Rheology for Viscous Mixtures Heat Transfer Suspension Homogenizing 1 3 6 7 (*) 1 3 6 7 (*) High circulation capacity Dissolution Homogenizing 1 2 3 . 7 10 11 . 1 2 . Dilution 1 3 7 10 . Dispersion 8 9 10 11 12 . 13 15 17 (**) High shearing strength Emulsion 8 16 . 2 8 9 14 15 17 . 1 3 6 16 . (*) Triblade efficient for high volumes at low rotation speeds Four blade efficient for low and medium volume at medium rotation speeds Water propeller efficient for high volumes requiring strong circulation Centripetal very efficient for dissolution because of the right compromise between circulation and shearing (**) Deflocculator / Sevin a Sevin insures better circulation at equivalent power input, specifically for high volumes Centrifuge very efficient for complex dissolutions Break=up very efficient for placing compact materials in suspension Centri=deflocculator very good compromise between the centrifuge and deflocculator STEP STEPSTEP STEP 5 55 5: :: : Calcul CalculCalcul Calculation of the various mixing parameters ation of the various mixing parametersation of the various mixing parameters ation of the various mixing parameters 1. 1.1. 1. Diameter, number and speed of one or more mixing rotor Diameter, number and speed of one or more mixing rotorDiameter, number and speed of one or more mixing rotor Diameter, number and speed of one or more mixing rotor(s) (s)(s) (s) These calculations are performed taking into account as main parameters one or several criteria for a precise mixture: • Criteria for mixing efficiency = peripheral speed, = recirculation rate therefore capacity of the turbine, = length of the mixing process. • Criteria linked to the rheology of the product (the higher the viscosity of the product, the higher the diameter of the rotor at low speed) • Economic criteria Guide GuideGuide Guide for selecting for selectingfor selecting for selecting the the the the D D D D tool tool tool tool / // /D DD D tank tanktank tank ratio ratioratio ratio in the tank Table III D DD D tool tooltool tool / D / D/ D / D tank tanktank tank Type TypeType Type of of of of Rotor RotorRotor Rotor Speed SpeedSpeed Speed ( (( (rpm rpmrpm rpm) )) ) Low viscosity product Low viscosity productLow viscosity product Low viscosity product Viscous product Viscous productViscous product Viscous product* ** * 3000 0,1 0,2 Rotor/Stator 1500 0,15 0,25 1500 to 750 0,2 0,3 500 to 250 0,25 0,5 170 to 90 0,3 0,6 Propeller or Turbine 60 to 30 0,5 0,8 Anchor or butterfly blade 10 to 200 0,9 à 1 *according to the number of movements DESIGNING A MIXER PAGE PAGEPAGE PAGE 6 66 6/ // /12 1212 12 ZI Nord - 85607 MONTAIGU Cedex - France Tel: 33 (0)2 51 45 35 35 – Fax: 33 (0)2 51 06 40 84 http:\www.rayneri.fr - E-mail : comm-rayneri@vmi.fr Guide for selecting the peripheral s Guide for selecting the peripheral sGuide for selecting the peripheral s Guide for selecting the peripheral speed and the recirculation rate peed and the recirculation ratepeed and the recirculation rate peed and the recirculation rate Table IV TYPE TYPE TYPE TYPE OF MIXTURE OF MIXTUREOF MIXTURE OF MIXTURE Speed in Speed inSpeed in Speed in m/s m/s m/s m/s Recirculation Recirculation Recirculation Recirculation volume bac/h volume bac/hvolume bac/h volume bac/h Maintaining in suspension, circulation: slow sedimentation product 0,5 to 1,5 50 to 200 Maintaining in suspension, circulation: fast sedimentation product 1,5 to 2,5 200 to 300 Liquid/liquid homogenizing 2,5 to 4 300 to 400 Liquid/solid homogenizing Relatively equal apparent densities Low concentration dissolution: 10 to 20 % max 4 to 5 400 to 700 Solid /liquid homogenizing Very different apparent densities High concentration dissolution: up to 50 % 5 to 8 700 to 1000 Dispersion facile 8 to 10 800 to 1200 Difficult dispersion • Products that swell • Extremely fine products • Mashing 15 to 20 1000 to 1500 Guide for selecting the number of Guide for selecting the number ofGuide for selecting the number of Guide for selecting the number of ro roro rotor tortor tors in the s in thes in the s in the tank tanktank tank Table V Viscosity ViscosityViscosity Viscosity Pa.s Pa.s Pa.s Pa.s No. No.No. No. of of of of mo momo movements vementsvements vements Height of work Height of workHeight of work Height of work (Nb of (Nb of (Nb of (Nb of times timestimes times Ø ØØ Ø) )) ) Flow rate factor Flow rate factorFlow rate factor Flow rate factor K K K K 0 00 0 0.001 (eau) 8 to 3 1.3 <0.1 3 to 2 1.2 0.1 to 10 1 movement 2 to 1.5 1 10 to 30 1.5 to 1 0.8 30 to 60 1 or 2 movements 1 0.6 60 to 100 0.8 0.5 100 to 1000 0.65 0.35 > 1000 2 movements minimum 0.5 0.2 2. 2.2. 2. Calcul CalculCalcul Calculation of the ation of the ation of the ation of the characteristic characteristiccharacteristic characteristic parameters of the mixer parameters of the mixer parameters of the mixer parameters of the mixer . • Sizes used: - D: diameter of the mixing tool (m) - N: rotation speed of the tool (t/s) - : apparent density of the liquid (kg/m 3 ) - µ: viscosity of the liquid (Pa.s) - N P0 : Number for nominal capacity - N P : Number for corrected capacity - N Q : Number of pumping actions - K S : Metzner=Otto constant to calculate shearing - K: Consistency index (Pa.s n=1 ) = n: exponent of rheoliquidifying; K and n are determined by a measure of viscosity where µ = K n=1 • Calculation of Reynolds number (Re) Newtonian liquids : Re = x N x D 2 /µ Non Newtonian liquids : Re equivalent = ( x N 2=n x D 2 )/K DESIGNING A MIXER PAGE PAGEPAGE PAGE 7 77 7/ // /12 1212 12 ZI Nord - 85607 MONTAIGU Cedex - France Tel: 33 (0)2 51 45 35 35 – Fax: 33 (0)2 51 06 40 84 http:\www.rayneri.fr - E-mail : comm-rayneri@vmi.fr • Calculation of the nominal capacity number N P0 = f(Re) Experimental values of Experimental values ofExperimental values of Experimental values of N N N N P0 P0P0 P0 = f(Re) = f(Re) = f(Re) = f(Re) (N (N(N (N P0 P 0P0 P0 = 1 for = 1 for = 1 for = 1 for Re = 10 Re = 10 Re = 10 Re = 10 4 44 4 ) )) ) Table VI Four blade Four bladeFour blade Four blade Re ReRe Re Triblade TribladeTriblade Triblade Profilée ProfiléeProfilée Profilée Water Water Water Water Propeller PropellerPropeller Propeller P A PAPA P A PSVB PSVBPSVB P SVB P SVH PSVHPSVH P SVH Centripetal CentripetalCentripetal Centripetal Deflocculator DeflocculatorDeflocculator Deflocculator SEVIN SEVIN SEVIN SEVIN with with with with inlets inletsinlets inlets 1 / 100 22,4 36,2 31,5 53 94 128 2 59 60 13,5 21 19 31 55 77 3 29,5 44 8,8 14,3 12,4 22 39 57 4 23,5 36 7,6 12,4 11,4 18 34 49 5 19,1 30 6,5 10,5 9,5 16 30 41 6 16,2 26 6,2 10 9 12 24 31 7 14,7 23,2 5,3 8,6 7,6 11 22 28 10 11,2 18 4,1 5,7 5,2 9,5 16 23 20 6,8 10 2,8 3,8 3,2 6 10 14 30 5,3 7,6 2,4 3,1 2,7 4,7 7,9 10,5 40 4,4 6 1,9 2,8 2,2 4 7 9 50 3,8 5,2 1,8 2,6 2 3,4 6 7,7 70 3,2 4,4 1,5 2 1,8 2,8 5 6,2 100 2,7 3,6 1,2 1,7 1,3 2,3 4 5,2 150 2,2 2,8 1,2 1,4 1,2 2 3 3,8 200 1,8 2,6 1,1 1,1 1,05 1,8 2,5 3,1 250 1,6 2,2 1,06 0,95 0,95 1,7 2,4 2,8 300 1,5 1,8 1, 0,95 0,95 1,7 2,2 2,6 500 1,2 1,4 0,95 0,86 0,86 1,5 1,8 2,1 1000 1,1 1,2 0,95 0,86 0,86 1,2 1,4 1,6 5000 0,94 1 1 0,95 0,95 1,05 1 1,05 10000 1 1 1 1 1 1 1 1 50000 1,03 0,88 1,06 1 1 0,96 1 0,97 100000 1,12 0,84 1,1 1,05 1,05 0,95 1 0,9 • Calculation of Froude number (Fr) if required (appearance of a vortex) Fr = N 2 x D/g (g=9,81 ms =2 ) A vortex will be considered formed if Fr , 3 • Calculation of corrected capacity number N P - If Fr - 1 (no vortex), then N P = N P0 - if Fr , 3 (vortex), then N P = N P0 x Fr y et y = (a – Log Re) / b radial effect rotors: a = 1 b = 40 axial effect rotors: a = 2,1 b = 18 • Calculation of absorbed pump power P ab (in W) P abs = N P x x N 3 x D 5 • Calculation of turbine flow rate Q (in m 3 /s) Q = N Q x N x D 3 • Calculation of drag flow rate Q e (the viscosity of the liquid is taken into account) Q e = Q x K 0 (flow rate factor, see Table V) • Calculation of recirculation rate T RC (in volume / hour) Directly deducted from the drag flow rate Q e and the volume V of the tank • Calculation of mixing time T m T m = K x V/Q e where K is an experimental coefficient varying from 10 to 10000 (tests from Grenville and Co in 1992 or Nienow in 1997) If K is unknown the value for K 0 can be used (Table V), and you will get: T m = K 0 /T RC • Calculation of peripheral speeds (V P ), flow speeds (or transversal) (V F ), and rising speed (V R ) Peripheral Speed (in m/s) (linear speed of the extremity of the turbine) DESIGNING A MIXER PAGE PAGEPAGE PAGE 8 88 8/ // /12 1212 12 ZI Nord - 85607 MONTAIGU Cedex - France Tel: 33 (0)2 51 45 35 35 – Fax: 33 (0)2 51 06 40 84 http:\www.rayneri.fr - E-mail : comm-rayneri@vmi.fr V P = .D.N Flow Speed (in m/s) (linear speed of the liquid in the turbine) V F = (4 x N Q x D x N)/ R ising Speed ( in m/s) (linear rising speed of liquids on the side of the tank) V R = (4 x Q)/ (D c 2 = D 2 ) = (V F x D 2 )/(D c 2= D 2 ) with D c = diameter of the tank DESIGNING A MIXER PAGE PAGEPAGE PAGE 9 99 9/ // /12 1212 12 ZI Nord - 85607 MONTAIGU Cedex - France Tel: 33 (0)2 51 45 35 35 – Fax: 33 (0)2 51 06 40 84 http:\www.rayneri.fr - E-mail : comm-rayneri@vmi.fr MIXING LEXICON MIXING LEXICONMIXING LEXICON MIXING LEXICON Behaviour index Parameter of Ostwald=Dewaele’s Law, the behaviour index defines the pseudoplastic character of a liquid for n<1 or dilatant for n>1. For n=1, the apparent viscosity is independent from the speed gradient, which defines a Newtonian liquid. Bingham A Bingham liquid is one that flows only if shearing stress is superior to a certain threshold 0 . Beyond this threshold, the product reacts like a Newtonian liquid, pseudoplastic or dilatant. Chocolate, toothpaste and drilling mud are examples of Bingham liquids. Consistency index Parameter of Ostwald=Dewaele’s Law the consistency index defines the consistency of a liquid. The higher the value of the index the higher the apparent viscosity, at a given speed gradient, is important Dilatant A dilatant like liquid is one whose apparent viscosity increases with the speed gradient. The rheologic model of Ostwald = Dewaele defines this liquid. The dilatant characteristic will be will be even more apparent as the behaviour index increases. Aqueous clay suspensions and some slush are examples of dilatant liquids. Dilution Dilution is the transformation of a concentrated solution to a more diluted solution by adding a continuous phase compatible with the solution. This operation requires an important circulation of the product. Dispersion Dispersion is the incorporation of a solid phase divided in a continuous liquid phase where the particles of the solid phase are not soluble in the liquid phase. Dissolution Dissolution is the incorporation of a soluble solid phase in a continuous liquid phase often called solvent. This operation requires good circulation. Emulsion An Emulsion is a mixture of two immiscible liquids. One liquid (the dispersed phase) is dispersed in the continuous phase. This operation requires a very high degree of shearing from the agitation rotor. The stability of the emulsion is essentially linked to the size of the droplets of the dispersed phase, their surface tension and distribution in the dispersed phased. Endothermic A reaction is endothermic when it absorbs heat. Dissolution of citric acid in water is endothermic . Exothermic A reaction is exothermic when it emits heat. Dissolution of soda in water is exothermic . DESIGNING A MIXER PAGE PAGEPAGE PAGE 10 1010 10/ // /12 1212 12 ZI Nord - 85607 MONTAIGU Cedex - France Tel: 33 (0)2 51 45 35 35 – Fax: 33 (0)2 51 06 40 84 http:\www.rayneri.fr - E-mail : comm-rayneri@vmi.fr Extraction Extraction is made up of the dispersion or suspension of a solid phase divided in a liquid phase obtaining a very high concentration that can reach 75% of the end product. Froude The Froude number is a dimensionless number (no units) comparing inertial and gravitational forces. It occurs only when gravitational forces are sensitive and it is characterized by the forming of a vortex on the interface of the liquid. Grinding Grinding is an activity that reduces the sizes of solid particles, either in a liquid phase or directly in its dry state. Homogenizing Homogenizing is the action of homogenizing a medium. This means that the value of a characteristic quantity (example = temperature or concentration) is identical in every part of the medium. Significant circulation of the product favours this operation. Laminar A discharge is laminar when the layers or threads of liquids slide one against the other without merging. It is characterized by a Reynolds number lower than a limit value which depends on the geometric conditions of the agitation system. The transversal motion of linear momentum is caused only by molecular momentum. Mixture The term mixture defines a system made up of several chemical species which can found in various states (solid, liquid, gaseous). To perform a mixture for which at least the dispersion phase is in liquid state, the agitation rotor creates two distinct actions: a pumping action to ensure a wide scale global mixture (macro=mixture) and a turbulent action or shearing to ensure a small scale local mixture (micro=mixture). Newton Newton’s Law expresses the quantity of motion transferred through a given surface, represented by the formula: d mV dt S dV dx ( ) =µ . Newtonian A liquid is Newtonian when its viscosity is constant when in given temperatures and pressures. Viscosity does not depend on operational conditions (speed gradient, shearing rate, time …). All gases, water, light organic products are Newtonian liquids. Non Newtonian A liquid is non=newtonian when its viscosity is dependent of operational conditions. Notably we can distinguish liquids for which the apparent viscosity depends on: = the speed gradient (pseudoplastic, dilatant, of Bingham) = the speed gradient and length of the application of the constraint (thixotropic, rheopectic) = the speed gradient, length of the application of the constraint and modulus of elasticity (viscoelastic). Ostwald>Dewaele Ostwald=Dewaele’s Law , also called power law, is the rheologic model used to characterize the behaviour of pseudoplastic and dilatant liquids. It expresses the apparent viscosity as a function of gradient speed using the equation: µ a n m= & 1 where m and n are respectively the consistency and behaviour index of a liquid.