Electrical Impedance Tomography

The Intelligent Electrical Tomography instrument was developed by En’Urga to provide imaging of multi-phase flow through pipes. The void fraction within the fluid cross-section is computed. The system is also capable of providing flow rate based on the void fraction by comparing the propgation of the phase distribution image from the upstream and downstream layers.

Highlights

• Fast scan rate of 500 Hz.
• 2 levels of data acquisition to obtain velocity with up to 16 electrodes per layer
• Inexpensive
• Suitable for small and large pipes
• No need for safety restraints

Applications

The instrument is very useful for flow diagnostics in the following industries

• Nuclear power generation industry
• Petrochemical transportation, production and processing
• Chemical
• Pharmaceutical
• Biological

Product Description

The system is customized based on user requirements but is of the general configuration below.

• A pipe section made out of delrin contains two or more layers of electrodes. The electrode surface is flush with the interior surface of the pipe and will not affect the flow.
• A metal jacket encloses the wires coming out of the electrodes, which are connected to female BNC connections.
• A control box containing the power supplies, multiplexer and control and measurements circuits plugs into the pipe section.
• The measurements from the control box are sent to a desktop computer with a data acquisition card and control software.

Operating Principle

The technology is based on measuring the impedance across the electrodes that are mounted flush to the inner surface of a pipe section. In principle, the EIT can function if the continuous phase of a flow mixture is electrically conducting. During each operating frame, multiple driving currents are sequentially fed into a pair of neighboring electrodes. For each driving current, the EIT measures the voltage through the remaining electrodes. With known values of electrical potentials and currents, the local conductivity (or resistivity) of the mixture can be reconstructed through a state-of-the-art optimization algorithm. The conductivity distribution is then further converted into a local phase concentration distribution based on Maxwell’s relation. By cross-correlating two distributions from both upstream and downstream planes, the local or zone-averaged phase distribution propagation velocities are obtained. Each statistical tomographic inversion is performed on the raw data to obtain visualization of the velocity field as well as void fractions within the spray or multi-phase flow.

All of En’Urga’s products are custom-made. Please provide details in the Contact Form for any modifications of performance specifications, or any change in the physical configuration of the desired instrument. A description of your application is helpful.