Electrical resistance tomography for process applications

Measurement of electrical resistivity via four probes is widely used in a variety of applications ranging from geophysical prospecting to silicon wafer manufacture. Electrical resistivity tomography is an extension of this approach and is performed via an array of equi-spaced electrodes mounted into the periphery of a process vessel to map non-intrusively the spatial distribution of resistivities within. The digitized boundary data are `inverted' by an image reconstruction algorithm to produce a map of the internal resistivity distribution. This paper focuses on the design and operation of flexible electrical resistivity tomography instrumentation for use on laboratory- and plant-scale process equipment.