Drying Equipments<br />
Drying Process<br />	Drying or Dehydration (term used for food) is the process of thermal removal of water to about 15-20%...
Process Diagram of Dehydration of Diced Potatoes<br />Stored Potatoes<br />Washing<br />Peeling<br />Dicing<br />Blanching...
Types of Dryers<br />Rotary-Drum Dryer<br />Rotary-Louver Dryer<br />Fluidized-Bed Dryer<br />Cabinet Tray Dryer<br />Tunn...
Rotary-Drum Dryer<br />Consists of a rotating drum 2 to 3 m in diameter and 15 to 20 m long. <br />The dryer is slightly i...
Heat Transfer Rate<br />
Rotary-Louver Dryer<br />Air passes a heater to give the optimum conditions for drying and then is forced by a fan into th...
Fluidized-Bed Dryer<br />	Fluidized-bed dryer are best and fastest drying systems for drying wet granular solids which do ...
Fluidized-Bed Dryer<br />
Schematic Representation of Moisture and Temperature Profiles in Fluidized-Bed Dryer<br />
Cabinet Tray Dryers<br />	Cabinet Tray Dryers are relatively small batch units for drying small quantities of product.<br ...
Cabinet Tray Dryers<br />
Tunnel (truck) Dryer and Conveyor Dryer<br />
Screw Conveyor and Mixer Dryers<br />	Screw conveyors with jacketed troughs and hollow augers are used for drying slurries...
Pneumatic (flash) Dryer<br />	The hot gas is conveying medium rapidly with velocity of order 25 m/s in which granular free...
Pneumatic (flash) Dryer<br />
Pneumatic Ring Dryer<br />
Spray Dryer<br />	Spray drying is an example of powder production from solution.<br />	Fine droplets produced by an atomiz...
Spray Dryer<br />
Classification of Various Types of Dryers<br />
Characteristics of Common Food Dryers<br />
Operating Conditions of Various Types of Dryers<br />
Drying Selection<br />Location<br />Material to be dried<br />Energy source<br />Initial cost per tonne of dryer capacity<...
Reference:<br />	Grain Drying: Theory and Practice by Stanislaw Pabis, Digvir S. Jayas, and Stefan Cenkowski © 1998 by Joh...
Upcoming SlideShare
Loading in …5
×

Drying equipments

12,347 views
11,710 views

Published on

Published in: Business, Technology
0 Comments
23 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
12,347
On SlideShare
0
From Embeds
0
Number of Embeds
16
Actions
Shares
0
Downloads
0
Comments
0
Likes
23
Embeds 0
No embeds

No notes for slide

Drying equipments

  1. 1. Drying Equipments<br />
  2. 2. Drying Process<br /> Drying or Dehydration (term used for food) is the process of thermal removal of water to about 15-20% moisture (dry basis), at ambient air condition.<br /> Dryer is a device that removes moisture by heating the mass to a level where it becomes safe to store.<br /> Batch dryers are used for solid throughputs (flows) below 50 kg/hr. Continuous dryers is preferred above 1000 kg/hr.<br />
  3. 3.
  4. 4. Process Diagram of Dehydration of Diced Potatoes<br />Stored Potatoes<br />Washing<br />Peeling<br />Dicing<br />Blanching<br />Inspection<br />Bin<br />Drying<br />Drying<br />Screening<br />Packing<br />
  5. 5. Types of Dryers<br />Rotary-Drum Dryer<br />Rotary-Louver Dryer<br />Fluidized-Bed Dryer<br />Cabinet Tray Dryer<br />Tunnel (truck) Dryer and Conveyor Dryer<br />Pneumatic (Flash) Dryer<br />Screw Conveyor Dryer<br />Spray Dryer<br />
  6. 6. Rotary-Drum Dryer<br />Consists of a rotating drum 2 to 3 m in diameter and 15 to 20 m long. <br />The dryer is slightly inclined toward the outlet.<br />The drum have flights used for lifting the substance.<br />Air temperatures are usually 120-175oC <br />Air velocity ranges from 2000-25,000 kg/m2h for coarse particles<br />
  7. 7. Heat Transfer Rate<br />
  8. 8. Rotary-Louver Dryer<br />Air passes a heater to give the optimum conditions for drying and then is forced by a fan into the dryer.<br />The air moves upward at about 0.5 m/s through the screen and then through the material, leaving at the discharge end.<br />
  9. 9. Fluidized-Bed Dryer<br /> Fluidized-bed dryer are best and fastest drying systems for drying wet granular solids which do not tend to stick or agglomerate. <br />Incipient fluidization is the point at which fluidization starts. At this stage the solids are loosened, and they will not contact each other. At this stage, the pressured drop slightly falls.<br /> The residence time of the material in the dryer is 30 – 120 sec for removing surface mixture. 15 – 30 min for removing moisture by internal diffusion.<br />
  10. 10. Fluidized-Bed Dryer<br />
  11. 11. Schematic Representation of Moisture and Temperature Profiles in Fluidized-Bed Dryer<br />
  12. 12. Cabinet Tray Dryers<br /> Cabinet Tray Dryers are relatively small batch units for drying small quantities of product.<br /> The product in the form of pieces, particles, or paste is placed in metallic trays, which are re-used for drying operations.<br />
  13. 13. Cabinet Tray Dryers<br />
  14. 14. Tunnel (truck) Dryer and Conveyor Dryer<br />
  15. 15. Screw Conveyor and Mixer Dryers<br /> Screw conveyors with jacketed troughs and hollow augers are used for drying slurries and wet particulate solids. <br />Screw conveyors are steam heated, heat transfer is mainly by conduction.<br /> These dryers are also known as hollow flight dryers, frequently used for drying waste materials and biomass (sludge) from wastewater treatment processes.<br />
  16. 16. Pneumatic (flash) Dryer<br /> The hot gas is conveying medium rapidly with velocity of order 25 m/s in which granular free flowing solid materials are dispersed.<br /> Finely powdered wet material is introduced into hot gas (air steam) with the help of a screw conveyor. <br /> The dried material is separated from air steam in a cyclone and bag filter. The product from the bottom of the collecting equipments (cyclone and bag filter) is transported to a silo via screw conveyor.<br />
  17. 17. Pneumatic (flash) Dryer<br />
  18. 18. Pneumatic Ring Dryer<br />
  19. 19. Spray Dryer<br /> Spray drying is an example of powder production from solution.<br /> Fine droplets produced by an atomizer are sprayed into a drying chamber and the powder is collected.<br /> Droplet sizes in the range of 10μm to over 100μm can be produced.<br />
  20. 20. Spray Dryer<br />
  21. 21. Classification of Various Types of Dryers<br />
  22. 22. Characteristics of Common Food Dryers<br />
  23. 23. Operating Conditions of Various Types of Dryers<br />
  24. 24. Drying Selection<br />Location<br />Material to be dried<br />Energy source<br />Initial cost per tonne of dryer capacity<br />Energy consumption per kilogram of water removed<br />Maintenance cost <br />Ease of operation<br />
  25. 25. Reference:<br /> Grain Drying: Theory and Practice by Stanislaw Pabis, Digvir S. Jayas, and Stefan Cenkowski © 1998 by John Wiley & Sons, Inc.<br />Fundamentals of Food Engineering by D.G. Rao © 2010 by PHI Learning Private Limited, New Delhi<br /> Physical Principles of Food Preservation, 2nd Edition, Revised and Expanded by Marcus Karel and Daryl B. Lund © 2003 by Marcel Dekker, Inc.<br /> Food Process Design by Zacharias B. Maroulis and George D. Saravacos © 2003 by CRC Press<br /> Ceramic Materials: Science and Engineering by C. Barry Carter and M. Grant Norton © 2007 Springer Science + Business Media, LLC<br /> Food Process Engineering and Technology by ZekiBerk © 2009 Elsevier Inc.<br />

×