This presentation was given at the DOE Office of Science-Environmental Management Science Program (EMSP) High-Level Waste Workshop held on January 19-20, 2005 at the Savannah River Site

Tavlarides, Lawrence L.

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Principal Investigators: L.L.Tavlarides, A. SanganiColleagues: A. Shcherbakov, E. Dievendorf, Y. Sehgal, P. Spelt, M. Greenwood, M. Norato, M. HedgesJanuary 19, 2005Department of Chemical Engineering and Materials ScienceSyracuse University Syracuse, NYAcoustic Monitor for Solids and Gas Measurements at Low Volume Fractionsi  i   li       l  iEMSP High Level Waste WorkshopSRNL,  Aiken, SCGrant No’s: DE-FG-7-96-ER14729DE-FG02-03 ER63658Motivations for Research• Desire to characterize and instantly monitor waste slurries by remote, non-intrusive methods for dilute slurries either at-tank or in-pipe• Potential of acoustic probes due to their non-intrusive nature, simple and safe operation, and ability to penetrate optically opaque suspensions• Applicability to measure solid concentrations in slurries in the presence of small amounts of gas bubbles• Applicability to measure gas concentrations in gas-liquid systemsOutline• Previous Work– Forward theory outline– Comparison of theory and experiments– Employ forward theory and experimental results to develop a highperformance prototype acoustic monitor for industrial application– Fabricate and commission an acoustic monitor with control and processing instrumentation– Develop a calibration technique for the acoustic monitor– Demonstrate acoustic monitor capabilities on surrogate slurries in the flow loop• Current Work– Develop a radiation-resistant housing with acceptable acoustic properties– Demonstrate application to SRS surrogate slurries over broad range of concentrationsv Demonstrate an application of this monitor on surrogate slurries at SRNL, Aiken, SCv Develop an acoustic probe for placement and measurements in mixing vesselsv Expand application to measure low gas concentrations in gas-liquid systemsAttenuation MechanismsViscous Attenuation:Energy dissipated in translationThermal Attenuation:Scattering (Acoustic Radiation Damping):Heat in Heat out (<heat in)• Particle is surrounded by a spherical shell of fluid• Particle-shell combination immersed in uniform suspension (the effective medium)• The properties of the effective medium are determined by solving the governing equations for the particle-shell combination so they are consistent with the averaged equations for the suspensionTheorySpelt et al., “Determination of Particle Size Distribution from Acoustic Wave Propagation”, Physics of Fluids, Vol. 11 ms, 1065—1080.Spelt et al., “Attenuation of Sound in Concentrated Suspensions: Theory and Experiments”, J. of Fluid Mech. Vol. 430, 51—86, (2001)Theory and Experiment: ComparisonResults of predicting the attenuation due to the presence of bubbles in solid-gas-liquid slurry and simply subtracting that attenuation from the total one.  Soda- lime glass spheres (15 µm) at 5% by volume were used for solids and air at 1.5*10-5% by volume was used for gas.Experimental and theoretical results for the attenuation in a mixture of polystyrene particles (mean radius 79 ± 3 µm and 1.8 µm standard deviation) in water at 0.05 volume fraction. Circles are experimental data, solid and broken lines are from the theory for monodispersed particles of 79 and 77 µm respectivelyTheory and Experiment: ComparisonExperimental and theoretical results for the attenuation as a function of volume fraction for different frequencies, using glass particles (63±8.5 µm radius) and glycerol. Solid lines are for the theory and markers for the experiments: 2.5 MHz (r), 3.5 MHz (ö), 4 MHz (»), 4.5 MHz(Œ), 5MHz(£).Low weight fractions –subject of the current workApproach to the High-Speed Concentration Measurements• Cyclic acquisition of the signals from up to 6 channels, validation of signals, averaging• FFT conversion ‡ Obtain the spectra• Combination of data from separate channels• Obtain the attenuation curve• Apply bubble elimination method (BEM)• On-line calculation of concentration using calibration data• Displaying and recording the instantaneous concentration dataTest Cell OperationNew Test Cell Housing Properties:Material: Ultem 1000 (Polyetherimide)Radioactive stability: 95% residual strength after 400 MRad (Co) exposureChemical Stability: HighUltimate Strength: 24500 psi tensileSignal Acquisition and Processing( ) fwfslfAAdf~log1−=αAttenuation of the acoustic signal in the slurry is determined astt ti  f t  ti  i l i  t  l  i  t i  Data acquisition software –Acoustic Control Panelt  i iti  ft  ti  t l l2.25 MHz spectrum2.25 MHz signal10 MHz signal 10 MHz spectrumExperimental Apparatus:Flow Loop DesignFeedTankFlow WindowPump-1F-1SideStreamSamplePortT-1 MixerBubblerExperimental Apparatus:Filtering System DesignFilterT-2F2F1P1P2P3FlowT-1to pumpfrom pumpSpool SectionMVSV-1SV-2CV-1BVSV-3PRV-1SV-4100 psig Air SourceCV-2 SV-6SV-511. Flow Loop Test Cell2. Reference Test Cell3. Pump4. Filter5. High Pressure Backpulse Vessel6. Computer-Controlled Valves7. Flowmeters2345267Experimental Set-Up: Test Cell and Backpulse SystemCalibration Experiments:SIMULANT SLUDGE TANK #8   Attenuation vs Concentration00.10.20.30.40.50.60 2 4 6 8 10 12SRS slurry concentration, wt%Averaged Attenuation, Np/cm   8.98 MHz7.03MHz5.08MHz3.125MHz00.0050.010.0150.020.0250 0.1 0.2 0.3 0.4 0.5Calibration Experiments: G800y = 0.3887xR 2 = 0.9988y = 0.8727xR2 = 0.9953y = 1.0926xR2 = 0.9975y = 1.5271xR2 = 0.97930.002.004.006.008.0010.000 2 4 6 8 10Concentration (wt %)Average Attenuation, Np/cm5 MHz8 MHz10 MHz7 MHzOn-Line Concentration Measurements with  Stepwise Solids Concentration IncreasesReal Time Concentration Data-20246810120 500 1000 1500 2000Time (s)Acoustic Concentration (wt%) 5 MHz7 MHz8 MHz10 MHz~0% ~0.5%~1%~2.5%~5%~8%0.63%0.83%2.23%4.56%7.25%Sample PortConcentration (wt%)Comparison of the Acoustic Monitor and Direct Concentration Measurements from the Sampling Port (G-800)01234567890 1 2 3 4 5 6 7 8 9Actual Concentration (wt%)Measured Concentration (wt%) y=x5 MHz7 MHz8 MHz10 MHzThe Influence of the Gas Phase on the Attenuation of Ultrasonic Waves2.5 wt% G-800 and 0.1 vol% air01234560 2 4 6 8 10 12 14Frequency (MHz)Average Attenuation (Np/cm)G-LS-LG-L + S-LS-G-LBubble Elimination ResultsMeasured concentration, G80000.511.522.533.51 41 81 121 161 201 241 281 321 361 401 441 481 521Time indexConcentration, wt%Attenuation@ 7 MHzBEM @ 3-9MHzNo Gas0.01vol%0.095vol%Conclusions1. Developed robust data acquisition system to continuously acquire attenuation spectra from 0.6 - 12 MHz for S-L, G-L, and S-G-L slurries with 6-pairs of ultrasonic transducers1.1. Rapid response time: 0.2—0.3 s1.2. Housing radiation stability and mechanical properties improvement1.3. Signal distortion compensation in transmission cables2. Linear calibration of attenuation vs. concentration demonstrated for2.1. G-800 ceramic spheres and kaolin-bentonite (0.5—10wt%) 2.2. SRS simulant sludge, tank #8 (~0.05—12wt%)3. Slurry flow loop permits performance evaluation of acoustic monitor for S-L, G-L, and S-G-L systems4. Demonstrated on-line/real-time measurement of S-L concentrations (0.0—10.0 wt%)5. Gas phase (0.005—0.1 vol%) attenuation interference can be removed to determine S-L attenuation in S-G-L mixturesFuture Work1. Test of Syracuse Acoustical Monitor (SAM) at Syracuse University flow loop with SRS sludges (two sludges and two supernates)2. Demonstrate SAM at SRNL Pilot Plant with SRS sludges3. Develop and demonstrate an acoustic probe for placement and measurement in mixing vessels4. Expand applications to measure low gas concentration in gas-liquid and gas-liquid-solid systems Bubbles motionSolution• The attenuation per unit length can be calculated as:• When the total volume fraction is small the above result can be extended to account for a non-uniform particle size distribution by integrating the attenuation caused by the particles over each size present:whereis the attenuation density andφ (a)da    is the volume fraction of a particle size range between a and a+da( ) ( )∑∞=+−=032 Re1223,ˆnnAnazaf φα( ) ( ) ( )daaafftot φαα ∑∞−=0,ˆ( )af ,α̂Bubble Elimination Results00.20.40.60.811.21.41.680 90 100 110 120 130Time (min)Concentration (wt%)7 MHzBubble Elimination Method0.95% G-80000.0050.010.0150.020.0250 0.1 0.2 0.3 0.4 0.5Experimental Set-Up: Backpulse System1. Flow Loop Test Cell2.   Reference Test Cell3.   Pump4.   Filter5.   High Pressure Backpulse Vessel6.   Computer-Controlled Valves7.   Flowmeters

Acoustic Monitor for Solids and Gas Measurements at Low Volume Fractions

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