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Crystallization and Crystallizers

PrefaceVarious Properties of CrystalsStructureIntroduction: crystallization energyAttachment energy and layer energySuperficial and molecular energiesSurface energyPeriodic chain and nature of facesFormCrystal system and habitNon-sphericity index (form index)Nyvlt coefficientsThe importance of form: porosityOrthogonal rate and form developmentForm modifier additivesConclusions: crystal characteristicsForm and specific surfaceChemical composition: hygroscopicitySurface striationsSurface roughnessAttrition on drying: vitrification on grindingSurface concavityColorFlow behaviorPurityElasticity constantsHardness, deformation and fractureFragility and ductility of crystalsAgglomeration in suspensionAttritionCrystal hardnessFracture resistanceAttrition in a stirred vessel [MER 01]PSD measurement of a crystalline populationSiftingThe Coulter particle counterSedimentationImage analysisCharacteristics of a crystal populationAnalytic expressions of particle size distributionMean size and solubilityCoefficient of variation and attritionCrystal Formation and GrowthCrystal formationPrimary nucleationCrystallizer crust formationSecondary nucleationMetastable zone: supersaturation established slowlyMeasurement of nucleation order nParameters influencing ATmaxPractical study of the metastable zone (cooling)Interpretation of latency timeNucleation by vaporization: a practical aspectNucleation in a crystallizer (calculation)Energetic theory of face growthHartmann and Bennema’s theory (1980)The presence of a solventMorphological importance and cleavageEnergy aspect and kinetic perspectiveKinetic growth theoriesGeneralDiffusion layer theoryIntegration mechanismsFundamental parametersGrowth of a K faceBidimensional nucleationSpiral growth [BUR 51]“Formation and spreading”Diffusion-integration combinationRetrodiffusion of solventConclusionsDrawing crystal shapes [DOW 80]Crystallization in a Sugar RefineryTheory of sugar crystallizationGrowth mechanismsNucleationSugar purity and weight ratioOrders of magnitudeBoiling delayDiffusivityViscosityI. Liquid viscosityMagma viscosityProperties of crystallized sugarCrystallization kineticsIntegration layer and diffusion layer combinationPractice of sugar crystallizationThe three crystallization techniquesSteps involved in industrial sugar crystallizationSeed preparationDewatering the massecuitesSugar refiningThermal exchange dataCrystallizers: Design and DimensionsIntroductionQualities of a crystallized productCrystallizersOverall balance of the crystallizer populationBalance of population with attritionContinuous homogenous crystallizer with attritionBatch with attritionAgitationThermal exchangeContinuous homogeneous crystallizer (CHC)CHC definitionCrystallizer with a draft tube and an internal exchangerDefinition of draft tubeClassification zonePurpose of classificationTheory of CHC without attritionOther valuesParameters to manageCHC series without attritionOperative relationship of a CHC without attritionInstallation possibilities of a CHC (population density)Modulation of crystal contentContinuous forced circulation crystallizer (CFCC)DescriptionResidence time of crystals in the installationEntry level in a vaporization bodyCrystallizer with fluidized bedPresentationSuspension and nucleation powerCalculation procedureLaboratory study of a fluidized bedElutriation columnsGeneralResidence time of crystals in the columnCalculation of different liquid flowsCrystallizer piston with scraped walls [ULL 86]DescriptionCalculation elementsBatch crystallizing: homogeneous vatDesign of batch crystallizersBatch crystallization methods (presentation)SeedingControlled supersaturationVat population densityConstant nucleation without growthGrowth without nucleationNucleation with growthChoice of crystallizationCooling or vaporizationContinuous operation or batch operationAgitation and thermal exchangeFragile crystalsVery thick slurryGranulometry spreadCrystal purityCascade of serial crystallizersParticles in the slurryPossible crystal dimensionsExploitation parametersOrder of magnitude for parametersResidence time and supersaturationCrystal content in slurryCalculation of thermal transferAgitation and attritionIncrustationsChecking the crystallizationSurface pollutionPrecipitation by chemical reactionDefinition of a crystallization micropilotUse of the pilotDefinition of pilot exchanger tubes: velocity in the tubesVelocity in the pilot tubesFriction on the tube wallHow should the blockages in the pilot be avoided?ConclusionCrystallization at high temperatureGeneral aim [BYR 02]The Verneuil methodThe Czochralski methodThe thermal gradient methodFilm productionCrystals in the order of a millimeterCalculation for continuous crystallizersCoolingSolvent vaporizationEstablishing the thermal transfer parametersBibliography

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