The influence of permittivity models on phantom images obtained from electrical capacitance tomography

Four different phantoms have been placed within the sensor field of an electrical capacitance tomography (ECT) system mounted on a bench-scale fluidized bed. The phantoms were created with fluid catalytic cracking catalyst particles having a packed-bed relative permittivity of 2.4. Linear back-projection (LBP) image reconstruction has been compared with iterative LBP for three permittivity models: parallel, series, and Maxwell model. The parallel permittivity model provides the best representation of the phantoms. Tubes of solids placed in an empty bed could only be reconstructed near the ECT wall, while voids created by immersion of an empty tube in a packed bed of solids could be imaged equally well at the centre or wall. After 500 iterations, the size of the phantom in the reconstructed image is in very good agreement with the actual size of the phantom.

[1]  J. Werther,et al.  Capacitance probes for solids volume concentration and velocity measurements in industrial fluidized bed reactors , 2000 .

[2]  Maurice Beck,et al.  Design of sensor electronics for electrical capacitance tomography , 1992 .

[3]  Tomasz Dyakowski,et al.  Applications of electrical tomography for gas-solids and liquid-solids flows : a review , 2000 .

[4]  T. Pugsley,et al.  The hydrodynamics of the high-density bottom zone in a CFB riser analyzed by means of electrical capacitance tomography (ECT) , 2000 .

[5]  G. E. Fasching,et al.  Observations of a fluidized bed using capacitance imaging , 1993 .

[6]  Ø. Isaksen,et al.  A review of reconstruction techniques for capacitance tomography , 1996 .

[7]  Artur J. Jaworski,et al.  The design of an electrical capacitance tomography sensor for use with media of high dielectric permittivity , 2000 .

[8]  William R B Lionheart,et al.  Reconstruction Algorithms for Permittivity and Conductivity Imaging , 2001 .

[9]  Tomasz Dyakowski,et al.  Application of capacitance tomography to gas-solid flows , 1997 .

[10]  Richard A Williams,et al.  Real time visualisation and analysis of dense phase powder conveying , 1999 .

[11]  M. Louge,et al.  Measurements of the effective dielectric permittivity of suspensions , 1990 .

[12]  Tomasz Dyakowski,et al.  Real time capacitance imaging of bubble formation at the distributor of a fluidized bed , 1995 .

[13]  Wuqiang Yang,et al.  An image-reconstruction algorithm based on Landweber's iteration method for electrical-capacitance tomography , 1999 .