In- und on-line Particle Size Analysis in Suspensions and Emulsions of high concentrations

Liquid dispersions having a high concentration of solid particles or droplets, typically are found in production processes and are usually totally opaque. For optical analysers sampling of a small partial flow from the main product stream combined with a high degree of dilution is required. Dilution not only causes an extensive preparation effort, but is often even not permissible at all in order to maintain the original state of dispersion.

For such applications, Ultrasonic Extinction provides an outstanding performance for particle size analysis of suspensions and emulsions. One of the major benefits of Ultrasonic Extinction is the ability to operate in media of high concentrations, which typically come along with wet process stages. A solid content between 5 to 50 % by volume is the typical range of concentration – ideal for the Ultrasonic Extinction, which by principle covers concentrations from 1%vol. up to pastes of 70%vol.

The key to success is the application of low energy sound waves. Instead of electromagnetic waves (light) Ultrasonic Extinction utilizes acoustic waves with 31 varying frequencies passing through a suspension or emulsion layer.

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, results in an attenuation spectrum that is converted into a particle size distribution of 31 classes.

Ultrasonic Extinction is independent from the level of transparency and thus, totally opaque materials can be analysed, like e.g. ore slurries, water in crude oil or coke slurries. Also paints, sugar pastes or pharmaceutical suspensions can be analysed successfully with the Ultrasonic Extinction principle.

Further, the method allows a rugged and robust probe design that resists typical process conditions such as high temperatures, pressures or chemically and mechanically aggressive media. The Ultrasonic Extinction based OPUS probe covers temperatures up to 120°C, pressures up to 40bar and the entire range of pH-value. For applications in hazardous atmospheres an ATEX compliant explosion-prove OPUS version is available.

The process adaptation of OPUS to vessels or to large pipes is simple and uses a 100mm adapter-flange. For smaller pipes or bypass-lines specific process adapters e.g. Flow-Through (FT) or Bypass-Adapters (BP) are available.

The evaluation and presentation of all relevant and characteristic particle size distribution data is done with the high-performance and intuitionally operated WINDOX software package. WINDOX performs both, the control of OPUS and data processing as well as the data communication to the process control system by TCP/IP, Profibus, or as digital or analogue signals.

For many years OPUS is successfully established in crystallization, grinding or homogenization processes and impressively proves its performance. Not for production plants only but also in pilot plants or lab-application OPUS is setting new standards.