Evaluation of electrical resistance tomography with voltage excitation compared with electrical capacitance tomography

Normally, a gas–solids flow should be non-conductive. With the increase in moisture content in a gas–solids flow, the non-conductive flow may become low-conductive. For the measurement of low-conductive materials, i.e. particles with high moisture content, in the pharmaceutical industry, both electrical capacitance tomography (ECT) and traditional electrical resistance tomography driven by current (ERTc) generate poor images. An ERT driven by voltage (ERTv) may be suitable for the measurement of materials with low-conductivity. In this research, ERTv is used for the measurement of a wet gas–solids flow with different moisture content and different flow patterns, as well as a gas–liquid flow with different flow patterns. In the meantime, ECT is also used for the same flow conditions for comparison. The measurement results of ERTv and ECT are evaluated by the correlation coefficient. The results show that ERTv is good for measurement of a gas–solids flow with high moisture content and a gas–liquid flow when the conductivity of the continuous phase is low or moderate, while ECT is suitable for the measurement of a dry gas–solids flow.