International Society for Industrial Process Tomography

An Electrical Impedance Tomography Sensor for Dynamic Two-Phase Flow Instrumentation

C. Dang^1,3*, M. Darnajou^1,3, G. Ricciardi¹, A. Beisiegel², S. Bourennane³, and C. Bellis⁴

¹ CEA Cadarache, STCP/LTHC, 13115 Saint-Paul-Les-Durance, France

² Framatome GmbH, Karlstein Technical Center, 63791 Karlstein, Germany

³ Ecole Centrale de Marseille, CNRS, Institut Fresnel UMR 7249, 13013 Marseille, FRANCE

⁴ CNRS, Laboratories of Mechanic and Acoustic, 13453 Marseille, FRANCE

^*Email: Chunhui.DANG@cea.fr

ABSTRACT

With the advantages of non-intrusion and high temporal resolution, Electrical Impedance Tomography (EIT) is a promising instrumental technology for dynamical multiphase flows. In the Laboratory of Thermal-Hydraulics in Core and Circuits (LTHC), a prototype of EIT sensor was developed with 16 electrodes. The stimulation and acquisition of the signals are both realized by the PXIe system from National Instrument. Applying an innovative stimulating strategy, i.e. the full scan strategy the sensor is estimated to have a nearly homogenous sensitivity field in the whole domain. A multiplexer was designed and manufactured in-house to route the stimulation signal to selected electrodes. The performance of the sensor was analysed, including the variation of impedance with excitation frequency, noise level, reliability of absolute measurement value and the repeatability. Two types of electrodes were tested: plate and point. Results showed that comparing to point electrode, the electrode-specific impedance of plate electrode is much smaller comparing to the bulk impedance; the noise level (Signal to Noise Ratio and Total Harmonic Distortion) is lower, and a better repeatability is observed. Several static experiments have been performed with static water inside and non-conductive plastic rods simulating bubbles, preliminary image reconstruction showed a good position agreement, while the estimation of dimension has a considerable error. The paper presents further plans in which the sensor will be installed in a vertical upward two-phase flow rig, with which different flow regimes could be obtained by controlling the flow velocity of water and gas. Through this, the ability of EIT sensor in dynamic two-phase flow tomography will be assessed, further improvements will be made.

Keywords Electrical Impedance Tomography (EIT), Dynamic two-phase flow, Full scan strategy, Performance analysis

Industrial Application: General