Richard A. Pappas

Ultrasonic technologies for advanced process monitoring, measurement, and control

Ultrasonic signals are well suited for characterizing of liquids, slurries, and multiphase flows. Ultrasound sensor systems provide real-time insitu measurements or visualizations, and the sensing systems are compact, rugged, and relatively inexpensive. The objective is to develop ultrasonic sensors that 1) can be attached permanently to a pipeline wall, possibly as a spool piece inserted into the line, and 2) can clamp onto an existing pipeline wall and be movable to another location. Two examples of systems based on pulse-echo and transmission signal analysis are used to illustrate some of the capabilities of ultrasonic online measurements with technologies that have applications in the nuclear, petrochemical, and food processing industries.

Noninvasive ultrasonic examination technology in support of counter-terrorism and drug interdiction activities: the acoustic inspection device (AID)

The Pacific Northwest National Laboratory (PNNL) has developed a portable, battery-operated, handheld ultrasonic device that provides non-invasive container interrogation and material identification capabilities. The technique governing how the acoustic inspection device (AID) functions, involves measurements of ultrasonic pulses (0.1 to 5 MHz) that are launched into a container or material. The return echoes from these pulses are analyzed in terms of time-of-flight and frequency content to extract physical property measurements (the acoustic velocity and attenuation coefficient) of the material under test. The AID performs an automated analysis of the return echoes to identify the material, and detect contraband in the form of submerged packages and concealed compartments in liquid filled containers and solid-form commodities. An inspector can quickly interrogate outwardly innocuous commodity items such as shipping barrels, tanker trucks, and metal ingots. The AID can interrogate container sizes ranging from approximately 6 inches in diameter to over 96 inches in diameter and allows the inspector to sort liquid and material types into groups of like and unlike; a powerful method for discovering corrupted materials or miss-marked containers co-mingled in large shipments. This manuscript describes the functionality, capabilities and measurement methodology of the technology as it relates to homeland security applications.

Non-invasive ultrasonic instrument for counter-terrorism and drug interdiction operations - the acoustic inspection device (AID)

The Pacific Northwest National Laboratory (PNNL) has developed a portable, battery-operated, handheld ultrasonic device that provides non-invasive container interrogation and material identification capabilities. The technique governing how the acoustic inspection device (AID) functions, involves measurements of ultrasonic pulses (0.1 to 5 MHz) that are launched into a container or material. The return echoes from these pulses are analyzed in terms of time-of-flight and frequency content to extract physical property measurements (the acoustic velocity and attenuation coefficient) of the material under test. The AID performs an automated analysis of the return echoes to identify the material, and detect contraband in the form of submerged packages and concealed compartments in liquid filled containers and solid-form commodities. This device utilizes a database consisting of material property measurements acquired from an automated, ultrasonic fluid characterization system called the Velocity-Attenuation Measurement System (VAMS). Both prototype technologies are discussed here. This manuscript describes the functionality, capabilities and measurement methodology of the technology as it relates to the material property measurements and homeland security applications.

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.

Development of Millimeter-Wave Velocimetry and Acoustic Time-of-Flight Tomography for Measurements in Densely Loaded Gas-Solid Riser Flow

The MFDRC was formed in 1998 to advance the state-of-the-art in simulating multiphase turbulent flows by developing advanced computational models for gas-solid flows that are experimentally validated over a wide range of industrially relevant conditions. The goal was to transfer the resulting validated models to interested US commercial CFD software vendors, who would then propagate the models as part of new code versions to their customers in the US chemical industry. Since the lack of detailed data sets at industrially relevant conditions is the major roadblock to developing and validating multiphase turbulence models, a significant component of the work involved flow measurements on an industrial-scale riser contributed by Westinghouse, which was subsequently installed at SNL. Model comparisons were performed against these datasets by LANL. A parallel Office of Industrial Technology (OIT) project within the consortium made similar comparisons between riser measurements and models at NETL. Measured flow quantities of interest included volume fraction, velocity, and velocity-fluctuation profiles for both gas and solid phases at various locations in the riser. Some additional techniques were required for these measurements beyond what was currently available. PNNL’s role on the project was to work with the SNL experimental team to develop and test two new measurement techniques, acoustic tomography and millimeter-wave velocimetry. Acoustic tomography is a promising technique for gas-solid flow measurements in risers and PNNL has substantial related experience in this area. PNNL is also active in developing millimeter wave imaging techniques, and this technology presents an additional approach to make desired measurements. PNNL supported the advanced diagnostics development part of this project by evaluating these techniques and then by adapting and developing the selected technology to bulk gas-solids flows and by implementing them for testing in the SNL riser testbed.

Ultrasonic methods for characterization of liquids and slurries

In the field of process monitoring and control technology, Pacific Northwest National Laboratory is utilizing unique technical capabilities and drawing upon knowledge gained through many years of government- and industry-sponsored research activities to develop and deploy advanced sensor and measurement systems for the monitoring and control of process operations. This includes non-invasive, on-line and realtime technologies that use ultrasound characterization to measure the physical and chemical properties of flowing materials, such as liquids and slurries. Ultrasonic velocity, attenuation, reflection coefficients, and scattering amplitudes are measurable parameters related to fundamental physical properties of fluids and slurries of interest to food processors and manufacturers of consumer products. Accordingly, ultrasonic methodologies have been developed that offer on-line, real-time analysis of many physical properties, including particle size distribution, concentration, settling and plug formation, fluid viscosity, density and shear rate, fouling and pipeline wall buildup detection, liquid-liquid interface detection, and chemical identity confirmation.