PNNL

Abstract

Staff at Pacific Northwest National Laboratory have developed a compact, non-invasive ultrasonic measurement technique that can be used to interrogate dense opaque fluids and slurries to characterize physical properties of density, solids concentration, speed of sound, and track changes in particle size. The ultrasonic sensing technique is based on the reflection of the ultrasonic signal in the pipe wall at the sensor-fluid interface. The density measurement depends upon the reflection at the interface; therefore, the probe can be used to measure the density of highly concentrated slurries that are very attenuative to ultrasound. The sensor transducers are mounted directly on the outside of the process container which becomes part of the measurement system. Multiple reflections within the wall are used to provide increased measurement sensitivity. Ultrasonic interrogation modalities that measure speed of sound, reflection coefficient, and attenuation can be used to characterize dense opaque suspensions and to provide real-time in-situ measurements of fluid and slurry physical properties. Ultrasound can be used for interrogation of many types of chemical processes at the laboratory and plant scale and can be applied in adverse environments. The techniques described here have been applied to non-invasive measurement of radioactive waste slurries during transport. Additional applications include process monitoring in vessels to track slurry mixing and settling. The robustness of the interrogation technique can provide techniques well suited to the harsh industrial environments.