Characterization of solid liquid suspensions utilizing ultrasonic measurements

Rapid, online, noninvasive measurements of the particle size and concentration of moderate to highly concentrated slurries is required for the efficient process measurement and control for many processes. High concentrations are often found in government applications such as waste remediation for the Department of Energy sites and in industrial applications such as chemical and pharmaceutical manufacturing. However, existing methods based on ultrasonic attenuation can become inaccurate for nondilute suspensions due to the complex interactions of ultrasonic waves with the constituents of the slurries. Further complications arise because of the necessity for careful transducer alignment. We are developing two measurements that help to overcome these difficulties, the ultrasonic backscattering and measurements of the diffuse field properties. The backscattering measurement is attractive because viscous, thermal, and inertial effects have small contributions to backscattering. Furthermore, the backscattering theories are simpler than attenuation theories and lend themselves to more stable inversion process. In addition, the measurements of backscattering and diffuse fields do not require long travel distances and can be performed with a single transducer thus eliminating alignment problems. We will present ultrasonic measurements on solid liquid suspensions designed to elucidate the particle size and concentration at high concentrations.