Ultrasonic technique for dispersed-phase holdup measurements

Abstract

An ultrasonic technique is developed to determine the dispersed-phase holdup of liquid-liquid dispersions by measuring the velocity of ultrasound in suspensions and emulsions. A time-average model is proposed which permits estimation of the dispersed-phase holdup from the overall transmission time of the sound pulses. A statistical analysis on the experimental data revealed that there is no significant difference between typical data and calculated holdup values [0.00 < < 0.40] for dispersions of xylene droplets in water. Important features of this technique are (a) the ultrasonic transducers may be located on the outside of the vessel wall and (b) the transient behavior of the dispersion as well as the axial holdup profile can be accurately monitored.

Laser capillary spectrophotometry for drop‐size concentration measurements

“…The reactor is also equipped with an ultrasonic technique to measure dispersed-phase volumetric fraction, which was developed by Bonnet and Tavlarides (1987). Bapat (1982) and Savastano et al (1987) estimated the dispersed-phase volumetric fraction by measurements of the flow rates of two phases in a CFSTR by assuming that their dispersion systems were homogeneous (7, = T~) :…”

Ultrasonic Characterizations of Solids Holdup in a Bubble Column Reactor

“…The ultrasonic technique measures the average solids holdup in the ultrasound path while direct sampling determines the collected local solids holdup. The simple time-averaged method utilized in this study does not account for the sound refraction and reflection of the solid phase on the transit time [3]. Uchida et al [11] and Warsito et al [12] have reported some experimental results obtained from low concentrations of solids (up to 3 wt.-%) and low gas velocity (up to 3 cm/sec).…”

Acoustic Probe for Solid-Gas-Liquid Suspension

“…Although acoustic probes have been commonly used for monitoring flows in single-phase fluids (McLeod, 1967), their application to monitor two-phase mixtures has not yet fully realized its potential. A number of investigators in recent years have therefore been involved in developing probes for measuring the volume fractions in liquid solid suspensions Martin et al, 1995) and in liquid-liquid suspensions (Bonnet and Tavlarides, 1987;Bonnet, 1988, Yi andTavlarides, 1993, Tsouris et al, 1995). In particular, showed that the acoustic technique can be used to determine both the velocity and the volume fraction of solids while Martin et al (1995) and showed that the acoustic probe can also be used to obtain information on the size distribution of the particles.…”

“…The symbols represent experimental data for the solidliquid (a) and solid-gas-liquid (+) slurries, and the curves represent the forward theory predictions for those slurries and the difference after subtracting the bubble attenuation. It is estimated by the DOE that cleanup of the entire nuclear weapons complex will take thirty years and require about $100 billion, while some outside estimates predict that it will cost at least twice that much (Garr 1992 suspensions Martin et al 1995) and liquid-liquid dispersions (Bonnet and Tavlarides 1987;Yi and Tavlarides 1990;. In particular, suggest that the acoustic technique can be used to determine both the velocity and the volume fraction of solids while Martin et al (1995) claim that the acoustic probe can be used to obtain information on the size distribution of the particles.…”

“…Bonnet and Tavlarides (1987) developed an ultrasonic technique which used the time-averaged model of Kuster and Toksoz (1974) to predict the dispersed phase volume fraction in liquid-liquid dispersions and suspensions based on the difference in travel time of the ultrasound in the pure materials and in the dispersion. This technique was later improved to account for effects of the dispersed phase (such as the sphericity and polydispersity of the drops) on the travel time by modifications to the time-averaged model (Yi and Tavlarides 1990;Tsouris and Tavlarides 1990;.…”