Agitator Design Principles for Bioprocessing and Pharmaceutical Applications

This is a course for individuals who must specify, operate, purchase or optimize fluid agitation equipment used for Bioprocessing and Pharmaceutical applications. Such applications range from simple tanks containing CIP solutions to broth and slurry tanks, compounding tanks and fermenters/bioreactors. The application technology ranges from simple to complex, and the construction methods range from standard to highly sanitary. A basic introduction to general agitator design principles is given, but the focus is specifically on applications found in the Bioprocessing and Pharmaceutical Industries.

Having a working knowledge of the terminology and technology used by agitator designers enables the attendee to assume a more active role in the purchase and operation of such equipment, instead of leaving everything in the hands of the vendors. The result can be a lower price paid by clearly specifying what is needed, while avoiding undersized equipment that can cause lost productivity. In the case of fermenters, proper information can even be essential to assure the right product is capable of being made, and that energy costs are minimized. Senior management can see how the agitator design can impact overall production and profit.

Learning Objectives

Upon completion of this course, you will:

• Be able to choose the right impellers for the job
• Understand how power and pumping are calculated
• Understand the basics of gas dispersion
• Understand the basics of heat transfer
• Understand sanitary design options
• Understand the merits of various seal configurations
• Gain a familiarity with bioprocessing sizing guidelines
• Understand what data are needed to design aerobic fermenters
• Be able to design a pilot fermentation protocol that will give such data
• Learn how to scale-up fermenters
• Learn how to minimize power consumption in fermenters.
• Understand the merits of various impeller types
• View a fermenter as a dynamic system

Course Description

This course presents a rather intense introduction to the major principles of agitator process design, as applied to liquid, solid-liquid and gas-liquid systems as commonly found in the Bioprocessing and Pharmaceutical industries. A brief introduction is given to the basics of agitation theory as applicable, but the emphasis is on practical application of theory, rather than as an academic treatise. Specific guidelines are given for major industry applications, and sanitary aspects are covered as well. The second day is devoted entirely to aerobic fermentation design and scale-up, as this is an area that has been most neglected in seminars of this kind.

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COURSE AGENDA

DAY ONE

Agitator design basics
• Nomenclature
• Principal dimensionless numbers, correlations
• Impeller classifications
• Flow patterns
• Agitated heat transfer

Design for liquid motion
• Calculating pumping capacity
• Characteristic velocity
• Scale of Agitation
• Why power and rpm are both important
• Sample problem
• Use of commercial software

Introduction to gas dispersion
• Dispersion mechanism
• Effects on power draw
• Flooding
• Holdup

Bioprocessing application classifications and guidelines
• Simple blending
• Cell culture bioreactors
• Anaerobic fermentation
• Aerobic fermentation

Sanitary design guidelines
• Shaft seals
• In-tank couplings
• Impellers
• Steady bearings

DAY TWO

Gas dispersion principles and issues
• Power
• Flooding
• Holdup
• Mass transfer

Pilot plant protocol
• The problem with most pilot studies
• Start with estimated correlation
• Estimate full scale design
• Design pilot runs to mimic full scale tentative design, ranging above and below
• Fit model to new pilot conditions

Full scale design, power optimization
• What to do if limited or no pilot data available
• Ideal: start with “good” mass transfer correlation
• Calculate peak OTR
• Calculate combinations of power, airflow meeting OTR.
• Minimize combined power

Impeller system design
• Impeller system design
• Impeller types
• Gassing factor effects
• Example of effects of impeller types
• Impeller size effects
• Example of effects of impeller size
• Viscous effects

Use of Computational Fluid Dynamics
• Flow around coils
• Velocity profiles
• Bubble Size Distribution
• Gas holdup distribution
• kla distribution
• Future technology

Conclusions
• Fermenter design is a complex subject
• Seldom is there sufficient data
• Both process and mechanical aspects are important
• Exciting things are developing for future design tools