On-line Electrical Impedance Tomography for Industrial Batch Processing

Abstract

This research was originally conceived under the auspices of the UK Government's Foresight Initiative, which aimed to translate the significant body of process tomography knowledge, residing in various British universities, towards applications of generic benefit to industry.In collaboration with the sponsoring life science company, Zeneca Ltd, a number of potential demonstrator projects were identified. Ultimately on-line imaging within pressure filtration was selected by virtue of its direct and broad benefit to the chemical sector and the opportunity to extrapolate the techniques developed towards other batch production processes.The research programme is centred around three empirical studies. These progress from an initial phase, where the early laboratory instrumentation was exposed to a constrained set of filtration conditions, through to the installation of a novel prototype industrial tomography system on to an existing large scale production unit, which was fabricated from an electrically conducting alloy and located in a potentially flammable atmosphere. During the course of these investigations electrical impedance tomography (EIT) was identified as the most viable modality for this class of application.The challenges associated with transferring the EIT technology into the manufacturing environment were addressed by taking advantage of the lenient frame rates acceptable within chemical batch monitoring to develop an instrument structure which was intrinsically safe, suitable for use with earthed metal vessels, tolerant to chemically aggressive media and amenable to three-dimensional image reconstruction via irregular, process compliant, electrode architectures. In the subject production filter a planar sensor array was exploited to provide a relatively uniform electrical field distribution within the process material, whilst not adversely affecting the normal operation of the plant item