On detecting mixing pathologies inside a stirred vessel using electrical resistance tomography

Electrical resistance tomography (ERT) has the capability to resolve the 3- D conductivity field inside a stirred mixing vessel using multiple planes o f axially spaced sensors. This capability has already been exploited to qua litatively image vortex formation and geometry, pseudo-stationary gas-liqui d mixing and unsteady dynamic brine tracer mixing inside a plant scale (1.5 m) stirred vessel (Mann et al, 1997(1)). This feature of qualitative imagi ng, arising from simplified reconstruction by back-projection, nevertheless can visualize key features of mixing characteristics without the need to r esort to extensive iterations to converge on quantitative images, This appr oach is therefore useful in detecting and identifying pathological behaviou r caused by equipment malfunction. Examples are presented for (i) misplaced gas sparger, (ii) inadvertent solids accumulation and (iii) displaced feed point behind a baffle.