Electrical Resistance Tomography

Electrical Resistance Tomography

Electrical Resistance Tomography (ERT) is a measurement technique for obtaining information about the contents of process vessels and pipelines. Multiple electrodes are arranged around the boundary of the vessel at fixed locations in such a way that they make electrical contact with the fluid inside the vessel but do not affect the flow or movement of materials.

What of the applications of the technique?

A typical application is real time monitoring of multicomponent flows within process engineering units. Specific applications where ERT has been successfully exploited include solid/liquid and liquid/gas mixing, hydrocyclones, packed columns, flotation columns, precipitation processes, liquid-liquid extraction and hydraulic conveying. In principle, ERT can be used to investigate and monitor any process where the main continuous phase is at least slightly conducting and the other phases and components have differing values of conductivity.

An ERT system produces a cross-sectional image showing the distribution of electrical conductivity of the contents of a process vessel or pipeline from measurements taking at the boundary of the vessel.

The p2+ system injects a current between a pair of electrodes and measures the resultant voltage difference between remaining electrode pairs according to a pre-defined measurement protocol.

This interrogates an entire ‘slice' through the measurement zone - analogous to a ‘body-scan' in medical imaging. A single measurement set consists of over 100 voltage measurements - the exact number depends on the pre-defined measurement protocol. An image reconstrcution algorithm processes the voltage measurements to determine the electrical conductivity distribution.

What is Electrical Resistance Tomography?

Electrical Resistance Tomography (ERT) is a measurement technique for obtaining information about the contents of process vessels and pipelines. Multiple electrodes are arranged around the boundary of the vessel at fixed locations in such a way that they make electrical contact with the fluid inside the vessel but do not affect the flow or movement of materials.

Should I use ERT/ECT in my process?

ERT should be used where the continuous material is electrically conducting (eg water acids bases and ionic solutions).

ECT should be used where the continuous material does not conduct electricity eg air/oil. If the process moves to from conducting to no-conducting or visa versa then a combined ECT/ERT system is recommended. Example of this might be polymerization, drying or multiphase flow.

Register to access a complete FAQ document.