Initial predictions of the internal flow patterns through the new reactor design were made using a CFD package and gave favourable results. But in many situations CFD models are difficult to validate, and the internal design of this particular catalyst bed, with a non-uniform porosity, made it particularly hard.

In this case, engineers performed validation of the CFD results using electrical resistance tomography (ERT) which uses instantaneous bursts of current to measure the conductivity of the fluid at a plane in the vessel. By injecting a higher conductivity fluid as a tracer and watching it progress through the vessel in time, engineers are able to measure mixing within the vessel.

Combining ERT results from multiple planes of the electrode array produces results which are a reasonable match with the CFD predictions.