Industrial Process Tomography

In this chapter we explore some of the differences between biomedical applications of electrical impedance and magnetic induction tomography and applications in industrial process monitoring. The very first attempt at electrical resistivity imaging (or at least electrical prospecting) was probably the Sclumberger brothers resistivity experiments in their mother's copper bath tub in Chateau 404de Crevecoeur, Normandy in 1912 [ 39 ]. However it was not until biomedical EIT became popular, largely from the work of Barber and Brown in the 1980s, that the use of low frequency electric currents were seriously studied, from the 1990s, as a way to non-invasively monitor vessels containing conductive fluids in industrial processes such as mixing and filtration. Much of the initial work was done by a group lead by Maurice Beck at UMIST in Manchester. The term Electrical Resistance Tomography (ERT) was coined for this technique (in slight contrast to Electrical Resistivity Tomography, as used in Geophysics, chapter 18). This technique followed closely the method used for test tanks (phantoms) by biomedical EIT researchers. A typical configuration being a single ring of sixteen circular or rectangular metal electrodes around a cylindrical vessel. Pairs of electrodes were excited with an alternating current while the magnitude of the voltage was measured on other electrodes. By contrast to biomedical applications using adhesive electrodes on the skin industrial process monitoring had the advantage of a rigid tank with regularly placed electrodes.