Hanford Tank Farms Waste Certification Flow Loop Phase IV: PulseEcho Sensor Evaluation

Abstract

Executive SummaryPhase III of the Washington River Protection Solutions (WRPS) certification loop testing indicated that the PulseEcho system is an excellent candidate for detecting settled bed formation in the waste certification test loop during slurry transfer operations between Hanford tank farms and the Hanford Tank Waste Treatment and Immobilization Plant (WTP). However, the Phase III work also identified some specific areas where further development was necessary. Some of these areas included using full schedule 40 SS pipe wall thickness to mount the transducers, repeatability of the measurements, ability of PulseEcho system to detect small high density particles, lower limit of the detectable solids concentration, and effect of commonly present non-settling components in Hanford tank wastes that can influence the attenuation of the PulseEcho signal. The Phase IV of the testing presented in this report was designed to address these gaps. Testing was conducted in the Multiphase Transport Evaluation Loop (MTEL) available in the Process Development Laboratory East (PDLE) test facility of PNNL. The evaluation included the 5-MHz transducer that was previously used in Phase III and a 10-MHz transducer specifically chosen for detecting critical velocities and settled bed formation with small (>20 µm) particles. Testing was conducted with simulants specifically chosen to enable comparison with the Phase III data and also to test the limits of detection with both the 5-and 10-MHz transducers. The results obtained lead to several conclusions and recommendations:1. For >50µm particles, the performance of the 5-MHz transducer mounted at the half wall thickness was repeatable as compared with Phase III results. In addition, the performance of the 5-MHz transducers mounted at both the full and half wall thickness yielded the same results for critical velocity. Therefore, this transducer can be mounted on a near full Schedule 40 pipe wall thickness.2. The 5-MHz transducer was not capable of detecting critical velocities and settling of particles less than 30 µm. However, the particle concentration threshold for this transducer for 30 µm particles was not evaluated.3. The detection of critical velocity for particles in the WRPS desired range of 20 µm and greater requires a 10-MHz transducer.4. It is recommended that the absolute threshold mode of operation be applied with the PulseEcho system when using the 10-MHz transducer. This will allow for detection of small particle settled beds even in the highly attenuated conditions expected with many small particles distributed in the slurry.5. For highly attenuative carrier fluids, the 10-MHz transducer was capable of detecting settling of 15-30 µm sized stainless steel particles without false indications at a particle concentration of 2 wt% or higher in the detectable size range. NOTE -This minimum concentration is applicable to the small, high density stainless steel particles utilized during Phase IV testing. Additional testing is required to determine the minimum weight p...