(758e) Scale-Up Oscillatory Helical-Baffled Reactor for Multiphase Reactions | AIChE

(758e) Scale-Up Oscillatory Helical-Baffled Reactor for Multiphase Reactions

Authors 

Phan, A. N. - Presenter, Newcastle University
Harvey, A. P., Newcastle University



Scale-up oscillatory
helical-baffled reactor for multiphase reactions

Anh N. Phan and Adam P. Harvey

School of Chemical
Engineering & Advanced Materials (CEAM), Newcastle University, NE1 7RU, UK

Corresponding to
anh.phan@ncl.ac.uk

Mesoscale
oscillatory helical-baffled reactor (MOHB), a helical wire embedded inside a
smooth tube without modification to the tube, was constructed and characterised
at very low net flow rates (net flow Reynolds numbers, Ren≤10)
over a wide range of oscillation conditions. The fluid mixing is controlled by
the oscillatory flow and is thus independent of net flow. The flow becomes
chaotic at high oscillatory Reynolds numbers and the secondary flow (swirling)
becomes active, which imposes an axial velocity component. The coupled effect
of the vortex flow and the swirling flow in the presence of helical baffles
augments the significant radial mixing and greatly broadens the
operating/design window of these reactors. Plug flow performance can be
achieved at a ratio of oscillatory Reynolds number to net flow Reynolds number
of approximately 10-250 and a helical turn to tube diameter ratio in a range of
0.2-0.6. The highest degree of plug flow was achieved at Strouhal
number 0.2<St≤0.1 and Reo=400-700 with the number of tanks
in series equal to the number of helical turns. At a scale of 5mm inner
diameter, the MOHB is considered to be effective
and robust in scale-down production of high added value products, decreasing
the reagents requirements and waste.

Is there a correlation between this mesoscale and a conventional scale? We scaled the mesoscale reactor up to 13 times and 130 times in volume by
maintaining geometrical parameters (opened cross-sectional area and helical
turn to tube diameter ratio) and oscillatory conditions.  It was found that the same mixing behaviour in
terms of residence time distribution profiles of tracers was obtained in the
large scales as in the mesoscale.

Keywords: scale-up, helical-baffled
reactor, oscillatory flow, plug flow

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