(207e) Investigation of Gas-Liquid Two-Phase Flow in Multiphase Contactor Using Low-Intrusive Measuring Methods

Investigation
of gas-liquid two-phase flow in multiphase contactor using low-intrusive
measuring methods

Guanghua
Zheng¹, Linda schlusemann¹,Markus Schubert²,
Uwe Hampel², Marcus Gruenewald¹

¹Ruhr-Universiy Bochum, Mechanical Engineering,
Universitätsstraße 150, 44780 Bochum, Germany. E-mail: zheng@fluidvt.rub.de

²Helmholtz-Zentrum Dresden-Rossendorf, Institute of Safety
Research, P.O. Box 510119, 01314, Dresden, Germany. E-mail: u.hampel@hzdr.de

Multiphase contactors are the most important apparatuses for reaction
and separation in chemical engineering. Limited
by the measuring methods, the analysis of their hydrodynamic behavior is
usually done using superficial liquid and gas flow velocities. Several new measuring techniques for the
investigation of multiphase flows in vessel cross sections have been developed
in the last decades. Especially the use of tomographic
visualization techniques is of great interest since these are noninvasive and
thus non-intrusive methods, and enable the visualization of phase
distributions.

However, currently
developed nonintrusive methods have considerable drawbacks. The computer
tomography methods can obtain high spatial resolution. In comparison, the
temporal resolution is relative low. For the application of topographic
measurement techniques in multiphase flows, especially with fast changing flow
patterns, a high temporal resolution is essential. Electrical
tomography has a high temporal resolution. However, reconstruction
algorithm is complex and the electrical field lines are not linear, therefore
spatial resolution rate is relative low. Therefore, no exact mass balance could be
established and the resulting phase fractions cannot be
applied for model developments.

In this
research, Wire-Mesh Sensor (WMS) is used for the study of phase distribution in
multiphase contactors (Figure 1).

Figure
 SEQ Figure \* ARABIC 1: Wire-Mesh
Sensor

The WMS comprises two planes,
in each plane there are sensing wires. Wires from different planes are
orthogonally arranged. Since water and air have different electrical
permittivity values and thus, produce different capacitances in the sensing
points of the WMS, images of phase distributions can be generated from the
measurements of the local capacitance.

Figure
 SEQ Figure \* ARABIC 2: Measurement
principle of Wire-Mesh Sensor

Phase distribution in
multiphase contactor, e.g. bubble column and packed column, were studied with a
WMS. It was shown that the flow regime in bubble column (Figure 3 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003300300036003000320034003300390034000000
) at various gas
superficial velocity ((a) u_G=8.4 cm/s; (b)
u_G=16.8 cm/s).

        
                    (a)                               
(b)

Figure  SEQ Figure \* ARABIC 3:
Visualization of flow regime at various gas flow velocities. (Colour bar denotes
the bubble phase fraction) 

Gas-liquid phase distribution of absorption process in packed column was
measured with WMS (Figure 4
and 5).

Figure  SEQ Figure \* ARABIC 4:
Visualization of phase distribution in structured packed columns.  (Colour bar denotes the liquid phase fraction)   

Figure  SEQ Figure \* ARABIC 5: Visualization of phase distribution
in random packed columns. (Colour bar denotes the
liquid phase fraction) 

Measurements of phase distribution with WMS
could supply more accurate information of spatial phase distribution to update
the theoretical models used in multiphase flow.