Spray drying processes and their influence on powder characteristics By Kaare Hvid Hansen, GEA Process Engineering A/S, GEA Niro
Agenda 1. Introduction 2. Spray dried powder types and their characteristics 3. Drying and pneumatic conveying methods 4. Test results 5. Wrap-up 2
Introduction: GEA Process Engineering, GPDK GEA Process Engineering HQ and GEA Niro Technology Centre Specialist in Spray and Freeze Drying > 600 employees 3
Introduction: Liquid to Powder Liquid Dried powder Packed powder Processes Homogenization Drying Agglomeration Processes Sieving Transport/Storage Packing Characteristics Components (protein, carbohydrate and fat) Colour Particles/droplets Characteristics Components Colour New characteristics Particles Characteristics Maintain characteristics 4
Introduction: What is Spray Drying? 5
Introduction Powder Handling after Drying
Introduction: Powder Characteristics and Spray Drying Powder parameters that can be influenced by the spray drying process Flowability Density Particle size distribution Wetability/Dispersability Retention of volatile components Mechanical stability Storage stability Moisture Hygroscopicity (glass transition) 7
Powder Types 9
Powder Types: Characteristics Fine single particles (d 50 < 100 µm) Large single particles (100<d 50 <300) Medium agglomerates (100<d 50 <250) Flowability Low Good Good Good Large agglomerates (250<d 50 <800) Density High High Medium Medium Particle size distribution Wide Wide Narrow Narrow Wetability Low Low High High Retention of volatile components Mechanical stability Low Medium High Medium High High Medium Medium to low Dust High Medium Low Low 11
Drying Methods: Spray Drying (SD) Small particle size Dusty Relative high powder temperature at max capacity for a short time High density possible Difficult to wet Direct coupling of powder moisture and drying 13
Drying Methods: FSD Spray Drying Medium particle size Non-dusty Relative low powder temperature/high moisture at max. capacity for a short time Uncoupling of primary drying conditions and powder moisture Easy to wet Medium mechanical stability 14
Drying Methods: FSD-Granulator Spray Drying Medium to high particle size Non-dusty Relative low powder temperature/high moisture at max. capacity for a short time Possible to encapsulate Uncoupling of primary drying conditions and powder moisture Easy to wet Medium mechanical stability 15
Drying Methods: FILTERMAT Spray Drying Medium to high particle size Non-dusty Lowest powder temperature at high moisture Possible to carry out controlled maillard reactions or crystallizations Uncoupling of primary drying conditions and powder moisture Easy to wet Low mechanical stability 16
Conveying Lean or Dense phase
Conveying Vacuum or Pressure Number of sources/destinations Distance (horizontal/vertical) Number of bends Powder Characteristics Air composition Mechanical stability
Test Results on Powder Formulation Location: GEA Niro test centre Plant size: 6,3 Configuration: SD, FSD, FSD-Granulation and FILTERMAT Two-fluid nozzle atomization Feed preparation: Batch Formula Mixer Two stage homogenisation (only 1) Formulation 1 and 2: Maltodextrin MD9, (Gum Arabic), Oil Temperature 40 C Dry matter 35% and 45% 20
Volume [%] Test Results on Encapsulation Powder Formulation 1 SD FSD FSD-Granulator Agglomeration Granulation SD FSD FSD-Granulator Particle size [µm] 21
Test Results on Encapsulation Powder Formulation 2 Median particle size d 50 (µm) SD FSD FSD-GRANULATOR FILTERMAT 34 119 329 111 Span (D 90 -D 10 )/D 50 2,5 1,4 1,7 1,7 Density, poured (g/ml) Density, tapped (g/ml) Residual moisture (%) 0,34 0,42 0,44 0,31 0,47 0,52 0,50 0,40 3,6 3,3 4,4 3,8 22
Wrap-up Always ask the following questions when turning a liquid into powder Which characteristics of material components are important Determines the possible drying methods What properties are expected of the powder Determines the set-up of the specific drying methods Is the process as a whole supporting the above objectives Take a holistic review of the total process and verify that none of the processes are working against each other 23