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Wolf-Gerrit Fr üh Heriot Watt University, Edinburgh email: w.g.fruh@hw.ac.uk. A smart chemical reactor: Mixing in a Taylor-Couette Reactor with Axial Flow. What is it? Why bother with it? What needs to be done – and how?. What is a Taylor-Couette reactor?.
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Wolf-Gerrit FrühHeriot Watt University, Edinburghemail: w.g.fruh@hw.ac.uk A smart chemical reactor:Mixing in a Taylor-Couette Reactor with Axial Flow • What is it? • Why bother with it? • What needs to be done – and how?
What is a Taylor-Couette reactor? • A rotating cylinder within a stationary cylindrical tank. • Mixing provided by rotation of inner cylinder • Operating controls: • Flow rates and • Rotation rate • Batch or continuous operation In continuous operation: reactants input at base or distributed; product extraction from top
Why should we consider it? • Forcing is by moving wall but flow is governed by global hydrodynamic instability • Uniform mixing throughout bulk of fluid • Uniform mixing/reaction conditions • Ideal both for batch and continuous operation. • Easy to control: • only rotation rate • and flow rates of fluids • Easy to maintain and clean (Just take the inner cylinder out … )
Flow types Depending on the rotation rate and flow rate: • Laminar rotational Couette and axial Poiseuille flow • Propagating Taylor vortices • Wavy propagating Taylor vortices • Turbulence • And many more…
Propagating Taylor vortices • Batch operation, or if vortices move with mean flow • separate cells, moving with mean flow, each with specified life time • If they move faster of slower • winding axial stream
Laminar Turbulent Vortices stationary in tank Concentration at outlet Vortices moving slightly faster than mean axial flow time Demonstration of mixing from: A. Syed and W.-G. Früh (2003). Journal of Chemical Technology and Biotechnology78, 227–235.
What needs to be done – and how? • Establish local and global mixing behaviour for range of flow conditions • Detailed simultaneous velocity and concentration measurements • Direct numerical simulation • Develop a design tool to predict outcome by characterising flow type • Extension and validation of advection-dispersion model of linked stirred-tanks system