Ultrasonic Extinction | In-line and On-line Particle Size and Concentration Analysis from below 0.1 µm to 3,000 µm
Liquid dispersions with a high concentration of solid particles or droplets, often totally opaque, are typically found in production processes. For optical analysers, sampling of a small partial flow of the main product stream combined with a high degree of dilution is required. Dilution not only causes an extensive preparation effort, but often changes the original state of the dispersion. For such applications, ultrasonic extinction provides an outstanding performance for particle size analysis of suspension and emulsions. One of the major benefits of ultrasonic extinction is the ability to operate in highly concentrated mediums, which typically come along with wet process stages. A solid content between 5 and 50 % by volume is the typical range of concentration. These are perfect conditions for ultrasonic extinction, which by principle covers concentrations up to 70 % by volume – typical for paste-like particulate systems.
Instead of electromagnetic waves (light), ultrasonic extinction applies low energetic sound waves. These waves are passing through a suspension or emulsion with 31 varying frequencies. For the introduction as well as the detection of sound waves, a piezo-electric RF-generator and detector set-up is used. The recorded loss of sound energy depends on the size and concentration of particles. A corresponding attenuation spectrum is determined and converted into a particle size distribution of 31 classes.
Using sound instead of light waves, ultrasonic extinction is independent of the level of transparency. Hence, totally opaque materials like ore slurries, water in crude oil or coke slurries, can be analysed. Furthermore, paints, sugar pastes, or pharmaceutical suspensions with high solids contents, rank as standard applications for the ultrasonic extinction principle.
