Development of an electrical tomographic system for operation in a remote, acidic and radioactive environment
G.T. Boltona, , M. Bennettb, M. Wangb, C. Qiua, M. Wrightc, K.M. Primrosea, S.J. Stanleyc and D. Rhodesc
aIndustrial Tomography Systems, 47 Newton Street, Manchester M1 1FT, UK
bSchool of Process, Environmental and Materials Engineering, University of Leeds, UK
cBNFL, Sellafield, Cumbria, UK
Abstract
The thermal oxide reprocessing plant (THORP) at Sellafield, Cumbria, UK, reprocesses fuel for nuclear power plants. It includes continuous stirred tanks into which reactants are added to produce a heavy metal precipitate. Stirring of the reaction vessel must be continuous and of the right intensity to ensure the precipitation process proceeds as intended. The tanks are operated with a deep vortex, the presence and depth of which provides valuable information on the performance of the precipitation.
Access to the tanks is restricted and visual inspection is difficult due to the opaque nature of the tanks’ contents and the presence of a heating jacket. Therefore, a remote method of measuring the vortex depth has been developed based on electrical resistance tomography. The sensor, which is in contact with the tank contents, has been designed to withstand the extreme combined conditions of high chemical reactivity, radiation and abrasion caused by the strongly acidic circulating flow. A data acquisition system (DAS) has been designed to cope with the demanding conditions caused by the high conductivity liquor and the constraint of a long cable between the DAS and the sensor.
A software user interface has been developed which displays the current vortex image and a historical trend of vortex depth. Images of the vortex are obtained using an image reconstruction algorithm based on linear back projection and further processing of these images provides the measurement of vortex depth. Low and high level thresholds can be set to trigger alarm conditions.
Keywords: Electrical; Tomography; Nuclear; Fuel; Reprocessing
Analysis of bubble behaviors in bubble columns using electrical resistance tomography
H. Jina, M. Wangb and R.A. Williamsb
aSchool of Materials and Chemical Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617, PR China
bInstitute of Particle Science & Engineering, School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT, UK
Abstract
The distribution of gas holdup, the rise velocity of gas bubble swarm and the Sauter mean bubble size are estimated with a small diameter laboratory scale bubble column using electrical resistance tomography (ERT). The theory of gas disengagement based on ERT methods has been developed for estimations of bubble size and bubble rise velocity. The gas holdups of large bubble swarm and small bubble swarm, the distribution of both bubble size are derived through the analysis of gas disengagement based on the differences of the rise velocity of bubble swarm at the cross-section imaged by electrical resistance tomography. Experimental results are in very good agreement with correlations and conventional estimation obtained using pressure transmitter methods. The proposed methodology can be also used as an analysis tool for quantifying and optimizing the performance of other types of complex reaction systems.
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Keywords: Bubble column; Bubble behavior; Electrical resistance tomography; Gas holdup
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