Development of a Gamma-Ray Process Tomography System for Hydrodynamic Characterisation of Multiphase Reactors

Abstract:

Gamma-ray computed tomography (CT) is a powerful non-invasive imaging technique for viewing an object in 2-D or 3-D cross-section images without the need to physically section it. The invention of CT technique revolutionised the field of medical diagnostic imaging because it provides more detailed and useful information than any previous non-invasive imaging technique. The method is increasingly used in industrial fields. This paper describes the development of a gamma-ray computed tomography system for imaging and visualising of industrial multiphase reactors. The theoretical aspects of CT scanner, the system configurations and the adopted algorithm for image reconstruction are discussed. Penetrating radiation from an isotopic gamma-ray source of Cs-137 and a bank of NaI(Tl) scintillation detectors in combination with a dedicated mechanical gantry set-up were used to construct the CT system. During scanning, the movement of the detector’s bank and rotation table is controlled by a LabView-based software. The software is also designed to control all associated nuclear electronics equipments and finally to acquire gamma-ray transmission data. The image reconstruction is performed by using Expectation-Maximisation (EM) and Alternating-Maximisation (AM) algorithms written in Visual-Fortran programming language. Several physical phantoms to simulate industrial multiphase process columns and reactors were scanned using this CT scanner. Some of the reconstructed images are presented in this paper.

• Periodical: Applied Mechanics and Materials (Volume 83)
• Pages: 41-47
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.83.41
• Online since: July 2011
• Authors: Abdullah Jaafar, Mohd Khairi Mohd Said, Nur Aira Abdul Rahman, Salzali Mohd, Mohamad Rabaie Shari, Nolida Yussop, Syirrazie Che Soh, Norizam Saad, Hearie Hassan, Mahadi Mustapha, Airwan Affandi Mahmood
• Keywords: Gamma-Ray Computed Tomography, Hydrodynamic Characterization, Image Reconstruction, Industrial Imaging, Multiphase Reactor, Non-Invasive, Process Tomography

References

[1] De Vuono A.C., Schlosser, P.A., Kulacki, F.A. and Munshi, P., 1980, Design of an Isotopic CT Scanner for Two Phase Flow Measurement, IEEE Trans. On Nuclear Sci., Vol. NS-27, No. 1, pp.814-820.

DOI: 10.1109/tns.1980.4330933

[2] Seville, J. P. K., Morgan, J. E. P. and Clift, R., (1986), Tomographic Determination of the Voidage Structure of Gas Fludized Beds in the Jet Region, Fluidization V, Proc. Of the 5th Int. Conf. on Fludization, Denmark, pp.87-93.

[3] Toye, D., Abdullah, J.B., Crine, M. and Marchot, P., (2005), 3D imaging of reactive packings with a new high energy x-ray tomography, Proceedings of 4th World Congress on Industrial Process Tomography, Aizu, Japan, 5th to 8th September (2005).

DOI: 10.1088/0957-0233/16/11/012

[4] Kantzas, A., (1994), Computation of Holdup in Fluidized and Trickle Beds by Computer Assisted Tomography, AIChE J., Vol. 40, No. 7, pp.1254-1261.

DOI: 10.1002/aic.690400716

[5] Christian, G. D., (1977), Analytical Chemistry, 2nd Edition, Wiley, New York (1977).

[6] Newton, T. H. and Potts, D. G., (1981), Radiology of the Skull and Brain, Vol. 5 : Technical Aspects of Computed Tomography, The C. V. Mosby Co., St. Louis.

[7] Lange, K. and Carson, R., (1984), EM Reconstruction Algorithms for Emission and Transmission Tomography, Journal of Computer Assisted Tomography, Vol. 8, No. 2, pp.306-316.

[8] Dempster, A. P., Laird, N. M. and Rubin, D. B., (1977), Maximum Likelihood Estimates form Incomplete Data via the E-M Algorithm, J. Roy. Statis. Soc., Vol. 39, Series B, pp.1-38.

[9] O'Sullivan, J. A. and Benac, J., (2007), Alternating minimization algorithms for transmission tomography, IEEE Trans. Med. Imaging, Vol. 26, p.283–97.

DOI: 10.1109/tmi.2006.886806