281661 Investigation of Gas-Liquid Two-Phase Flow in Multiphase Contactor Using Low-Intrusive Measuring Methods

Tuesday, October 30, 2012: 10:10 AM
408 (Convention Center )
Guanghua Zheng1, Linda Schlusemann1, Markus Schubert2, Uwe Hampel2 and Marcus Gruenewald1, (1)Mechanical Engineering, Ruhr-University Bochum, Bochum, Germany, (2)Institute of Safety Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany

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) uG=8.4 cm/s; (b) uG=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.


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