HYDRODYNAMIC STUDIES OF BUBBLE CUTTING IN A
MICRO-STRUCTURED BUBBLE COLUMN REACTOR FOR A DODECANE-NITROGEN SYSTEM

Krushnathej THIRUVALLUVAN SUJATHA, J.A.M. KUIPERS, Niels G. DEEN^*

¹ Department
of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O.
Box 513, 5600MB Eindhoven, The Netherlands  

Corresponding
author?s e-mail: N.G.Deen@tue.nl

Keywords: Micro-Structured Bubble Column, Digital Image
Analysis, dodecane ? nitrogen system, wire mesh

Bubble column reactors are one of
the widely used types of multiphase reactors in the chemical industry. They are
used for both two phase (gas-liquid) and three phase (gas-liquid-solid)
processes. Despite the advantages of simple construction and easy operation,
they have some inherent disadvantages. To overcome the disadvantages of a
conventional slurry bubble column reactor, a novel reactor concept is proposed
in this work.  It is a micro-structured bubble column reactor (MSBC), where the
micro-structuring is realized by a wire-mesh. It is intended to break the gas
bubbles and have an impact on the gas-liquid contact area in the bubble column,
depending on the wire-mesh geometry. The wire-mesh can be coated with a
catalyst to perform heterogeneous catalytic reactions.

The scope of this research is to
study the effect of the wire-mesh layout on the bubble cutting in a dodecane(C₁₂H₂₆)
? nitrogen (N₂) system. The bubble break-up is a function of mesh
opening and wire diameter. The objective of the present work is to obtain
detailed experimental data to understand the effect of the wire mesh on the
hydrodynamics in a dodecane - nitrogen system. These data will be used for
validation of a discrete bubble model (DBM) simulations. For more details on the
DBM, the reader is referred to the work of Jain et. al. (2013).

Experiments are conducted in a
MSBC for different flow configurations, by varying the superficial gas/liquid
velocities and also for different wire-mesh lay-outs. Experiments are done with
wire meshes with an open area exceeding 60%. An advanced digital image analysis
(DIA) technique developed by Lau et al. (2013) is used to determine the bubble
size distribution and the gas holdup in the column. The effect of surface
tension on bubble cutting is analyzed by comparing the results with an
air-water system. The gas and liquid velocities are determined using Particle
Image Velocimetry (PIV).

REFERENCES:

JAIN,
D., LAU, Y. M., KUIPERS, J. A. M., & DEEN, N. G. (2013). ?Discrete bubble
modeling for a micro-structured bubble column?, Chemical Engineering
Science,100, 496?505.

LAU,
Y.M., THIRUVALLUVAN SUJATHA, K., GAEINI, M., DEEN, N.G., KUIPERS, J.A.M.,
(2013), ?Experimental study of the bubble size distribution in a pseudo-2D
bubble column?, Chemical Engineering Science, 98,
203?211

Fig 1: Bubble
cutting with a 3.7 mm wire mesh at a superficial gas velocity of 15 mm/s for
air-water system.

Fig 2: Bubble
cutting with a 5.5 mm wire mesh at a superficial gas velocity of 15 mm/s.
Lamella fomation and re-coalescence of bubbles can be observed. for air-water
system.

Fig 3: Evolution of bubble size distribution
above and below the wire mesh at a superficial gas velocity of 10 mm/s. The
mesh opening is 3.7 mm.