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Three-dimensional electrical capacitance tomography

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Electrical Capacitance Volume Tomography (ECVT) is a non-invasive 3D imaging technology applied primarily to multiphase flows. It was first introduced by W. Warsito, Q. Marashdeh, and L.S. Fan [1] as an extension of the conventional Electrical Capacitance Tomography (ECT). In conventional ECT, sensor plates are distributed around a surface of interest. Measured capacitance between plate combinations is used to reconstruct 2D images (tomograms) of material distribution. In ECT, the fringing field from the edges of the plates is viewed as a source of distortion to the final reconstructed image and is thus mitigated by guard electrodes. ECVT exploits this fringing field and expands it through 3D sensor designs that deliberately establish an electric field variation in all three dimensions. The image reconstruction algorithms are similar in nature to ECT; nevertheless, the reconstruction problem in ECVT is more complicated. The sensitivity matrix of an ECVT sensor is more ill-conditioned and the overall reconstruction problem is more ill-posed compared to ECT. The ECVT approach to sensor design allows direct 3D imaging of the outrounded geometry. This is different than 3D-ECT that relies on stacking images from individual ECT sensors. 3D-ECT can also be accomplished by stacking frames from a sequence of time intervals of ECT measurements. Because the ECT sensor plates are required to have lengths on the order of the domain cross-section, 3D-ECT does not provide the required resolution in the axial dimension. ECVT solves this problem by going directly to the image reconstruction and avoiding the stacking approach. This is accomplished by using a sensor that is inherently three-dimensional.

Principles

ECVT reconstruct a volume image of various materials in the imaging domain through utilizing nonlinear distributions of electric field lines.

The ECVT system consists of the following components

  • ECVT sensor
  • Data acquisition system
  • Computer for data recording and image reconstruction[2]

Advantages

The ECVT technology provides low profile and flexibility of capacitance sensors, an increase in the number of imaging frames per second, and relatively low cost. These features moved the technology to the top of the list as a tool that could be used in industrial imaging.[2]

Applications

ECVT is applied for multi-phase flow systems measurements. The ECVT would provide Measurements in real-time in a three-dimensional components of multi-phase reactors. The ECVT could be applied to gas-liquid and gas, gas-solid fluidized bed, gas-solid circulating fluidized beds, liquid-solid bubble columns, and multi-phase flows in vessels with complex geometries.[2]

See also

References

  1. ^ Warsito, W.; Marashdeh, Q.; Fan, L.S. (2007). "Electrical Capacitance Tomography". IEEE Sensors. 7: 525–535.
  2. ^ a b c Wang, Fei; Marashdeh, Qussai; Fan, Liang-Shih; Warsito, Warsito (2010-03-09). "Electrical Capacitance Volume Tomography: Design and Applications". Sensors. 10 (3): 1890–1917. doi:10.3390/s100301890. PMC 3264458. PMID 22294905.{{cite journal}}: CS1 maint: unflagged free DOI (link)
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