Table Of ContentEdited by
Evangelos Tsotsas and
Arun S. Mujumdar
Modern Drying Technology
Modern Drying Technology
Editedby E.Tsotsas andA.Mujumdar
Other Volumes
Volume 1: Computational Tools at Different Scales
ISBN:978-3-527-31556-7
Volume 2: Experimental Techniques
ISBN:978-3-527-31557-4
Volume 3: Product Quality and Formulation
ISBN:978-3-527-31558-1
Forthcoming Volumes
Volume 5: Process Intensification
ISBN:978-3-527-31560-4
Modern Drying Technology Set (Volumes 1 – 5)
ISBN:978-3-527-31554-3
Edited by
Evangelos Tsotsas and Arun S. Mujumdar
Modern Drying Technology
Volume 4: Energy Savings
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V
Contents
Series Preface XI
Preface of Volume 4 XV
List of Contributors XIX
Recommended Notation XXIII
EFCE Working Party on Drying; Address List XXIX
1 FundamentalsofEnergyAnalysisofDryers 1
IanC.Kemp
1.1 Introduction 1
1.2 EnergyinIndustrialDrying 2
1.3 FundamentalsofDryerEnergyUsage 3
1.3.1 EvaporationLoad 3
1.3.2 DryerEnergySupply 4
1.3.3 EvaluationofEnergyInefficienciesandLosses:Example 5
1.3.3.1 DryerThermalInefficiencies 6
1.3.3.2 InefficienciesintheUtility(HeatSupply)System 8
1.3.3.3 OtherEnergyDemands 13
1.3.4 EnergyCostandEnvironmentalImpact 14
1.3.4.1 PrimaryEnergyUse 14
1.3.4.2 EnergyCosts 14
1.3.4.3 CarbonDioxideEmissionsandCarbonFootprint 15
1.4 SettingTargetsforEnergyReduction 16
1.4.1 EnergyTargets 16
1.4.2 PinchAnalysis 17
1.4.2.1 BasicPrinciples 17
1.4.2.2 ApplicationofPinchAnalysistoDryers 19
1.4.2.3 TheAppropriatePlacementPrincipleAppliedtoDryers 21
1.4.2.4 PinchAnalysisandUtilitySystems 24
1.4.3 DryingintheContextoftheOverallProcess 25
1.5 ClassificationofEnergyReductionMethods 26
1.5.1 ReducingtheHeaterDutyofaConvectiveDryer 28
1.5.2 DirectReductionofDryerHeatDuty 29
1.5.2.1 ReducingtheInherentHeatRequirementforDrying 29
VI Contents
1.5.2.2 AlteringOperatingConditionstoImproveDryerEfficiency 30
1.5.3 HeatRecoveryandHeatExchange 31
1.5.3.1 HeatExchangeWithintheDryer 31
1.5.3.2 HeatExchangewithOtherProcesses 32
1.5.4 AlternativeUtilitySupplySystems 32
1.5.4.1 LowCostutilities 33
1.5.4.2 ImprovingEnergySupplySystemEfficiency 33
1.5.4.3 CombinedHeatandPower 34
1.5.4.4 HeatPumps 36
1.6 CaseStudy 37
1.6.1 ProcessDescriptionandDryerOptions 37
1.6.2 AnalysisofDryerEnergyConsumption 38
1.6.3 UtilitySystemsandCHP 42
1.7 Conclusions 43
References 45
2 MechanicalSolid–LiquidSeparationProcessesandTechniques 47
HaraldAnlauf
2.1 IntroductionandOverview 47
2.2 DensitySeparationProcesses 51
2.2.1 FrothFlotation 51
2.2.2 Sedimentation 54
2.3 Filtration 61
2.3.1 CakeFiltration 61
2.3.2 SievingandBlockingFiltration 72
2.3.3 CrossflowMicro-andUltra-Filtration 73
2.3.4 DepthandPrecoatFiltration 75
2.4 EnhancementofSeparationProcessesbyAdditionalElectric
orMagneticForces 80
2.5 Mechanical/ThermalHybridProcesses 83
2.6 ImportantAspectsofEfficientSolid–LiquidSeparationProcesses 85
2.6.1 ModeofApparatusOperation 85
2.6.2 CombinationofSeparationApparatuses 87
2.6.3 SuspensionPre-TreatmentMethodstoImproveSeparation
Conditions 91
2.7 Conclusions 94
References 95
3 EnergyConsiderationsinOsmoticDehydration 99
HosahalliS.RamaswamyandYetenayetBekeleTola
3.1 Scope 99
3.2 Introduction 100
3.3 MassTransferKinetics 101
3.3.1 Pretreatments 101
3.3.2 Product 102
Contents VII
3.3.3 OsmoticSolution 103
3.3.4 TreatmentConditions 103
3.4 ModelingofOsmoticDehydration 104
3.5 OsmoticDehydration–TwoMajorIssues 105
3.5.1 QualityIssues 105
3.5.2 EnergyIssues 106
3.5.2.1 Osmo-ConvectiveDrying 107
3.5.2.2 Osmo-FreezeDrying 109
3.5.2.3 Osmo-MicrowaveDrying 111
3.5.2.4 Osmotic-VacuumDrying 113
3.6 Conclusions 114
References 116
4 HeatPumpAssistedDryingTechnology–OverviewwithFocuson
Energy,EnvironmentandProductQuality 121
SachinV.JangamandArunS.Mujumdar
4.1 Introduction 121
4.2 HeatPumpDryingSystem–Fundamentals 122
4.2.1 HeatPump 122
4.2.2 Refrigerants 125
4.2.3 HeatPumpDryer 127
4.2.4 AdvantagesandLimitationsoftheHeatPumpDryer 130
4.3 VariousConfigurations/LayoutofaHPD 131
4.4 HeatPumps–DiverseOptionsandAdvances 132
4.4.1 Multi-StageHeatPump 132
4.4.2 CascadeHeatPumpSystem 133
4.4.3 UseofHeatPipe 134
4.4.4 ChemicalHeatPump(CHP) 135
4.4.5 AbsorptionRefrigerationCycle 138
4.5 MiscellaneousHeatPumpDryingSystems 140
4.5.1 Solar-AssistedHeatPumpDrying 140
4.5.2 Infrared-AssistedHeatPumpDryer 143
4.5.3 Microwave-AssistedHeatPumpDrying 143
4.5.4 Time-VaryingDryingConditionsandMulti-ModeHeat
PumpDrying 145
4.5.5 HeatPumpAssistedSprayDrying 147
4.5.6 ModifiedAtmosphereHeatPumpDrying 148
4.5.7 AtmosphericFreezeDryingUsingHeatPump 149
4.6 ApplicationsofHeatPumpDrying 150
4.6.1 FoodandAgriculturalProducts 150
4.6.2 DryingofWood/Timber 150
4.6.3 DryingofPharmaceutical/BiologicalProducts 152
4.7 SizingofHeatPumpDryerComponents 153
4.8 FutureResearchandDevelopmentNeedsinHeatPumpDrying 156
References 158
VIII Contents
5 ZeolitesforReducingDryingEnergyUsage 163
AntoniusJ.B.vanBoxtel,MoniekA.Boon,HenkC.vanDeventer,
andPaulJ.Th.Bussmann
5.1 Introduction 163
5.2 ZeoliteasanAdsorptionMaterial 164
5.2.1 Zeolite 164
5.2.2 ComparingtheMainSorptionPropertiesofZeolitewith
otherAdsorbents 166
5.3 UsingZeolitesinDryingSystems 168
5.3.1 DryingSystems 168
5.3.2 DirectContactDrying 169
5.3.3 AirDehumidification 170
5.4 EnergyEfficiencyandHeatRecovery 173
5.4.1 DefiningEnergyEfficiency 173
5.4.2 EnergyRecoveryforaSingle-StageSystem 174
5.4.3 EnergyRecoveryinaMulti-StageSystem 176
5.4.4 EnergyRecoverywithSuperheatedSteam 178
5.5 RealizationofAdsorptionDryerSystems 180
5.5.1 AdsorptionDryerSystemsforZeolite 180
5.5.2 AdsorptionWheelVersusPackedBed 181
5.5.3 ZeoliteMechanicalStrength 182
5.5.4 LongTermCapacityofZeolite 183
5.5.5 ZeoliteAdsorptionWheel 183
5.6 Cases 185
5.6.1 Zeolite-AssistedDryingintheDairyIndustry 185
5.6.2 Zeolite-AssistedManureandSludgeDrying 189
5.6.3 DirectContactDryingofSeedswithZeolites 191
5.7 EconomicConsiderations 193
5.8 Perspectives 195
References 196
6 SolarDrying 199
JoachimMüllerandWernerMühlbauer
6.1 Introduction 199
6.2 SolarRadiation 200
6.3 SolarAirHeaters 204
6.4 DesignandFunctionofSolarDryers 210
6.4.1 ClassificationofSolarDryers 210
6.4.2 SolarDryerswithNaturalConvectionforDirectSolarDrying 212
6.4.3 SolarDryerswithNaturalConvectionforIndirectDrying 213
6.4.4 SolarDryerswithForcedConvectionforDirectDrying 214
6.4.5 SolarDryerswithForcedConvectionforIndirectDrying 218
6.4.6 DryerswithRoof-IntegratedSolarAirHeaters 223
6.5 SolarDryingKinetics 226
6.5.1 EmpiricalDryingCurvesinSolarDrying 226
Contents IX
6.5.2 EquilibriumModelforSolarDryingKinetics 227
6.6 ControlStrategiesforSolarDryers 231
6.6.1 AirflowManagementDuringtheNight 231
6.6.2 RecirculationofDryingAir 232
6.6.3 Back-UpHeatingSystems 232
6.7 EconomicFeasibilityofSolarDrying 234
6.7.1 DryingofTimberinBrazil 235
6.7.2 DryingofTobaccoinBrazil 237
6.8 ConclusionsandOutlook 239
References 242
7 EnergyIssuesofDryingandHeatTreatmentforSolidWood
andOtherBiomassSources 245
PatrickPerré,GianaAlmeida,andJulienColin
7.1 Introduction 245
7.2 WoodandBiomassasaSourceofRenewableMaterial
andEnergy 245
7.3 EnergyConsumptionandEnergySavingsintheDrying
ofSolidWood 254
7.3.1 Kiln-DryingofSolidWood:ARealChallenge 254
7.3.2 TheConventionalDryingofWood 258
7.3.2.1 TheDesignofConventionalKilns 258
7.3.2.2 DryingTimeandEnergyEfficiency 259
7.3.3 TheoreticalEvaluationoftheKilnEfficiency 263
7.3.4 TwoCaseStudiesofKilnEfficiency 266
7.3.5 RulesforSavingEnergy 269
7.3.5.1 EnergySavingsinConventionalKilns 269
7.3.5.2 EnergySavingbyAlternativeTechnologies 270
7.4 PreconditioningofBiomassasaSourceofEnergy:Drying
andHeatTreatment 271
7.4.1 ImportanceofBiomassDryingasaPreconditioningStep 271
7.4.1.1 DryersforBiomass 273
7.4.1.2 NumericalApproachtotheContinuousDryingofWoodyBiomass 276
7.4.2 InterestofHeatTreatmentasaPreconditioningStep 281
7.5 Conclusions 287
References 289
8 EfficientSludgeThermalProcessing:FromDryingto
ThermalValorization 295
PatriciaArlabosse,Jean-HenryFerrasse,DidierLecomte,MichelCrine,
YohannDumont,andAngéliqueLéonard
8.1 IntroductiontotheSludgeContext 295
8.1.1 Origin,ProductionandValorizationIssues 295
8.1.2 Sludge:AComplexMaterial 297
8.1.3 UsefulPropertiesforEnergyValorization 299
X Contents
8.2 SludgeDryingTechnologies 300
8.2.1 GeneralRemarks 300
8.2.2 ConvectiveDryingMethodsandDryerTypes 301
8.2.3 IndirectContactDryingMethodsandDryerTypes 305
8.2.3.1 RotorDesignandOperationoftheDryingProcess 306
8.2.3.2 DryingPerformances 308
8.2.4 SolarDryingandDryerTypes 310
8.2.5 CombinedandHybridDrying 311
8.2.6 SludgeFrying,anAlternativetoConventionalDrying 311
8.2.6.1 HeatandMassTransferDuringFry-Drying 312
8.2.6.2 EnergyandEnvironmentalAspects 313
8.2.7 PathogenReduction 314
8.3 EnergyEfficiencyofSludgeDryingProcesses 315
8.3.1 SpecificHeatConsumptionofSludgeDryers 315
8.3.2 TowardstheReductionofEnergyConsumptionAssociated
withSludgeDrying 316
8.3.3 CaseStudies 316
8.4 ThermalValorizationofSewageSludge 318
8.4.1 GeneralDescriptionoftheThermalProcessesAvailable
forSewageSludge 318
8.4.2 DesiredWaterContentforThermalProcesses 319
8.4.3 IncludingaDryingStepBeforeThermalValorization 320
8.5 EnergyEfficiencyofThermalValorizationRoutes 321
8.5.1 ImportanceofDryerEfficiency 321
8.5.2 CombiningSludgeDryingandThermalValorizationby
IntegratingonSite 322
8.6 Conclusions 324
References 325
Index 331
Description:This multivolume work covers drying, a key industrial processes that accounts for about 10-percent of total energy consumption in industry. It guides engineers towards achieving energy savings through such approaches as improved apparatus design, optimization, and heat recovery. In so doing, it po
