aeration and agitation

1. 113-09-19
AERATION AND AGITATION IN BIOREACTORS
- MANAL.M.R
MEENU MERLIN.M
MOHAMED ARIF.Z
Balamuragan. K

2. SYNOPSIS
 Introduction
 Main functions of aeration and agitation
 What is the need for aeration and agitation
 Structural components of a fermenter
 classification of agitators
 Stirrer glands and bearings
 Baffles
 The aeration system
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3. INTRODUCTION:
• Agitation ensures that a uniform suspension of
microbial cells is achieved in a homogenous
nutrient medium.
• Aeration refers to the process of introducing air
to increase oxygen concentration in liquids
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5. MAIN FUNCTION OF AERATION AND AGITATION:
• The main function of aeration is to supply enough
oxygen to the microbes in submerge culture technique
for proper metabolism.
• while agitation provides proper mixing of the nutrient
so that each and every organisms get proper nutrients.
• Each fermentation process requires unique type
of aeration and agitation system.
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6. WHAT IS NEED FOR AERATION AND AGITATION
• To disperse the air bubbles
• To suspend the cells.
• To enhance the heat and mass transfer
• Blending miscible liquids.
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7. THE STRUCTURAL COMPONENTS:
• The agitator (impeller).
• Strirrer glands and bearings
• Baffles
• The aeration system(sparger)
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8. CLASSIFICATION OF AGITATORS:
• Disc turbines
• vaned discs turbines
• variable pitch open turbines
• propellers
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9. DISC TURBINE:
• A Disc with a series of rectangular vanes set in a
vertical plane around the circumference
• break up a fast air stream without itself becoming
flooded in air bubbles
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10. VANED DISC:
• A series of rectangular vanes attached vertically to the underside
• Air from the sparger hits its underside and the air gets displaced
Towards the vanes
• Results in destruction of air bubbles
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11. VARIABLE PITCH OPEN TURBINE:
• Vanes are attached directly to a boss on a agitator shaft
• Air bubbles hit any surface by its action
• Flood when superfial velocity exceed 21m/h
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12. MARINE PROPELLER:
• Blade are attached directly to a boss on the agitator shaft
• Air bubbles hits surface
• A single row shear impeller
• Mainly used in the animal cell culture
• Flood when superficial velocity exceed 21m/h
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13. MODERN AGITATOR:
• Rushton disc turbine
• Scaba 6SRGT
• Prochem maxflow T
• Lightening A315
• Ekato interning
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14. STIRRER GLANDS AND BEARINGS:
• Sealing of stirrer shaft difficult problem in the construction of fermentation equip
• Entry of stirrer shaft-top,side or bottom
• Basic types of seal assembly
THE STUFFING BOX(PACKED GLAND SEAL)
THE SIMPLE BUSH SEAL
THE MECHANICAL SEAL
THE MAGNETIC DRIVE
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15. THE STUFFING BOX:
• The shaft is sealed by several layers of packing rings of asbestos or cotton, yarn,
Pressed against the shaft by a gland follower
• Chain et al.(1954) used two stuffing boxes on the agitator shaft with a space in between
Kept filled with steam
• These seals are sufficient for the requirements of GILSP containment
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16. THE MECHANICAL SEAL:
• The seal is composed of two parts one part is stationary
in the bearing housing
• The other rotates on the shaft , and the two componets
are pressed together bySprings are expanding bellows .
• The two meeting surfaces have to be precision machined
the moving surface normally Cosists of a carbon-faced
unit while the stationary unit is of stellite-faced stainless
steel
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17. THE MAGNETIC DRIVE:
• The problems of providing a stationary
seal when the impeller shaft passes
through the top or bottom plate of the
fermenter may be solved by the use of a
magnetic drive in which the impeller
does not pierce the vessel.
• A magnetic drive consist of two
magnets: one driving and the one
driven
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18. Double mechanical seal
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19. BAFFLES:
• Metal strips
• 1/10th of the vessel diameter
• Attached radially to the wall
• 4 baffles(normal)
• Wider baffles-high agitation effect
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20. • Narrow baffles –low agitation effect
• Can be attached with cooling
• Not found in lab scale fermenters
• Verticle baffles – increased aeration
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21. AERATION SYSTEM
• SYN:sparger
• A device which introduce air into medium
•
• Has a pipe with minute holes(1/64-1/32)inch or large)
• Hole allows air under P to escape into medium
• For mycelial growth-1/4 inch holes
• Impeller blades disperse air released through through sparger into medium
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22. SPARGER TYPES
• POROUS
• ORIFICE
• NOZZLE
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23. POROUS SPARGER
• Made of sintered glass, ceramics or metals
• Used mainly on a large scale fermenters
• Bubble size produced -10-100 times larger than pores
• Throughout of air is low-P drop across
• Clogging of pores
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24. Porous sparger
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25. ORIFICE SPARGER:
• Those with drilled air holes on their under surface of the tubes making up ring or cross
• Without agitation used to a limited extend in yeast manufacture and effluent treatment
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26. NOZZLE SPARGER
Modern mechanically stirred fermenters use them
• Single open or partially closed pipes
• Ideally, positioned centrally below impeller
• Causes lower P drops
• No clogging of pores
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27. REFERENCE:
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Principles of fermentation technology
PETER F.STANBURY,ALLAN WHITAKER AND STEPHEN J.HALL

28. THANK YOU
2813.09.19