Resistance Tomography (ERT) for Liquid-Solid Two-Phase Flow Detection

Background

In processes such as slurry transport, crystallisation, particle suspension and stirring, the distribution and concentration of solid particles in the liquid phase directly affect product quality, equipment wear and the risk of pipe blockage. Conventional sampling and assay can only reflect a local state offline and at a point, making it hard to grasp the cross-sectional phase distribution continuously. Electrical Resistance Tomography (ERT) images the liquid-solid distribution in real time without disturbing the flow field, by exploiting the conductivity contrast between the solid and liquid phases — an online, non-intrusive detection route for this kind of process.

Technical challenges

• The liquid-solid conductivity contrast varies with concentration; weak contrast requires a high-resolution front-end and a robust reconstruction algorithm
• The solid phase is unevenly distributed and prone to settling, so full-cross-section imaging is needed rather than single-point measurement
• Slurry is highly conductive and corrosive / abrasive, so contact electrodes must balance a wear-resistant structure with long-term consistency
• The flow state changes quickly, so the imaging frame rate must keep up with the transient evolution of the phase distribution

Demonstration

Based on the TJUERT multi-plane resistance tomography system, a contact-electrode array is placed around the pipe / vessel cross-section; a small current is injected and the boundary voltages are acquired to reconstruct the conductivity distribution within the cross-section. This video is a lab-stage imaging demonstration: as the relative distribution of the liquid and solid phases changes, the reconstructed image shows solid-accumulation regions and concentration gradients in sync, validating the feasibility of ERT “seeing” liquid-solid two-phase flow.

Value

• Phase-distribution visualisation: solid accumulation, segregation and settling form identifiable high / low-conductivity regions in the image
• Concentration tracking: cross-sectional average and local concentration can be output continuously over time for process monitoring and early warning
• Non-intrusive, no flow disturbance: electrodes are flush with the wall, with no probe protruding into the flow path
• Customisable: the number of electrode planes, layout and reconstruction algorithm can be customised to pipe diameter, medium, flow velocity and on-site cadence

This case is a technology-capability demonstration / proof of concept showing the capability of Electrical Resistance Tomography (ERT) in liquid-solid two-phase flow detection. For a solution assessment targeting a specific process, contact us.