Attenuation measurements with ultrasonic diffraction grating show dependence upon particle size of slurry and viscosity of base liquid.

How can using an ultrasonic diffraction grating lead to slurry characterization? The diffraction grating, which is formed by machining triangular grooves on the flat surface of an aluminum unit, has send and receive transducers fastened to the unit at an angle of 30°. The ultrasonic beam strikes the back of the grating, in contact with the slurry, and reflects a beam to the receive transducer; m = 0 and m = 1 beams are transmitted into the slurry. The angle of the m = 1 beam changes with frequency and, at the critical frequency f, it reaches 90°.

Design of ultrasonic attenuation sensor with focused transmitter for density measurements of a slurry in a large steel pipeline.

To design an ultrasonic sensor to measure the attenuation and density of slurry carried by a large steel pipeline (diameter up to 70 cm) is the goal of this research. The pitch-catch attenuation sensor, placed in a small section of the pipeline, contains a send unit with a focused transducer that focuses the ultrasound to a small region of the receive unit on the opposite wall. The focused transducer consists of a section of a sphere (base ∼12 cm) on the outer side of the send unit and a 500 kHz piezoelectric shell of lead zirconate titanate epoxied to it.

Particle size and density of a slurry from ultrasonic backscattering measurements at a solid interface.

The pivotal experiment was performed with a setup in which a plastic cylinder was mounted on the top of a horizontal Rexolite plate and a transducer mounted directly below the cylinder; a single layer of stationary 1588-μm acrylic spheres was placed in the cylinder filled with water. Two well-separated signals were received by the transducer operating in the pulse-echo mode: (1) a signal due to the reflection from water at the interface and (2) a time-delayed signal resulting from the backscattering from the spheres of diameter D. The important observation was that the time delay was equal to 2 D/c using standard notation.

Simulation of ultrasonic-driven gas separations.

The separation of components in a gas mixture is important for a wide range of applications. One method for achieving this separation is by passing a traveling acoustic wave through the gas mixture, which creates a flux of the lighter components away from the transducer. A series of simulations was performed to assess the effectiveness of this method for separating a binary mixture of argon and helium using the lattice kinetics method.

Ultrasonic diffraction grating spectroscopy and the measurement of particle size.

The results of measurements using ultrasonic diffraction grating spectroscopy (UDGS) are found to be dependent upon the particle size of the slurry. This illustrates the emergence of a new technique for measuring particle size. Theoretical calculations are underway to describe and predict them as well.

Inline ultrasonic rheometry by pulsed Doppler.

This will be a discussion of the non-invasive determination of the viscosity of a non-Newtonian fluid in laminar pipe flow over the range of shear rates present in the pipe. The procedure used requires knowledge of the flow profile in and the pressure drop along a long straight run of pipe. The profile is determined by using a pulsed ultrasonic Doppler velocimeter.

Measurement of the viscosity-density product using multiple reflections of ultrasonic shear horizontal waves.

We have developed an on-line computer-controlled sensor, based on ultrasound reflection measurements, to determine the product of the viscosity and density of a liquid or slurry for Newtonian fluids and the shear impedance of the liquid for non-Newtonian fluids. A 14 MHz shear wave transducer is bonded to one side of a 45-90 degrees fused silica wedge and the base is in contract with the liquid. Twenty-eight echoes were observed due to the multiple reflections of an ultrasonic shear horizontal (SH) wave within the wedge.

Measuring fluid and slurry density and solids concentration non-invasively.

Staff at Pacific Northwest National Laboratory have developed a highly sensitive, non-invasive, self-calibrating, on-line sensor to measure the density, speed of sound, and attenuation of ultrasound for a liquid or slurry flowing through a pipeline; the approach can also be applied for measurements made in vessels. The sensor transducers are mounted directly upon the stainless steel wall and the pipeline wall becomes part of the measurement system. Multiple reflections within the stainless steel wall are used to determine the acoustic impedance of the liquid, where the acoustic impedance is defined as the product of the density and the speed of sound.

Ultrasonic diffraction grating spectroscopy and characterization of fluids and slurries.

The ultrasonic diffraction grating is formed by machining triangular grooves, 300 microns apart, on a stainless steel surface. The grating surface is in contact with the liquid or slurry. The ultrasonic beam, traveling in the solid, strikes the back of the grating and produces a transmitted m=1 beam in the liquid.

Using ultrasonic attenuation to monitor slurry mixing in real time.

Staff at Pacific Northwest National Laboratory have developed and applied a simple ultrasonic attenuation measurement to measure slurry concentration in real time during suspension of solids settled in a large tank. This paper presents a simple single frequency ultrasonic measurement technique that demonstrates the ability of ultrasonic sensors to measure slurry concentration. Sensor calibration data show that in this attenuation regime ultrasonic signal attenuation is proportional to the applied frequency and to the slurry volume fraction.

Measurement of viscosity and shear wave velocity of a liquid or slurry for on-line process control.

An on-line sensor to measure the density of a liquid or slurry, based on longitudinal wave reflection at the solid-fluid interface, has been developed by the staff at Pacific Northwest National Laboratory. The objective of this research is to employ shear wave reflection at the solid-fluid interface to provide an on-line measurement of viscosity as well. Both measurements are of great interest for process control in many industries.

Ultrasonic sensor to measure the density of a liquid or slurry during pipeline transport.

This paper describes the design and testing of a computer-controlled sensor for the real-time measurement of the density of a liquid or slurry. It is to be deployed at the US Department of Energy's Hanford Site in Richland, WA, to monitor slurry properties during radioactive waste transfers. To demonstrate the sensor performance, tests were carried out using non-radioactive waste simulants and the results will be presented.