R. Daniel Costley

Torsional Waveguide Sensor for Molten Materials

Viscosity of the molten glass is a key variable in determining the quality of the final glass product. At low viscosities the melt can be highly corrosive. At high viscosities the melter can become plugged. “Melt viscosity is the most important processing property; it controls processing rate, product homogeneity, and heat transfer within the molten glass [1]. “ Thus, the viscosity is an important parameter which can be used by the vitrification industry for the processing of waste material and by the glass industry for production of high quality glass products. The major problem in measuring the viscosity of the molten waste product is the extremely hot and corrosive environment.

Temperature and Viscosity in-Situ Sensor for Hostile Processes

Viscosity of a fluid is known to affect the reflection of shear waves from a solid/fluid interface. In this paper, we will discuss the experimental work to simultaneously measure both temperature and viscosity of a fluid at very high temperatures using a buffer rod technique. The sensor is based on the effect of melt viscosity on ultrasonic shear wave reflections from the solid-melt interface. We have used refractory materials for the solid buffer rod delay line which is water cooled. The sensor has been calibrated using various calibration samples and has been tested for repeatability. A portable instrument and a database has been created for temperatures up to 1500 degree Celcius. The results based on this sensor and their interpretations will be discussed. This sensor can find applications both as a process monitor as well as a tool for improving melter design for high temperature melt processes.

Sensor Development for High Temperature Viscosity Measurement

In previous years, we have presented several results on viscosity measurements using conventional and laser ultrasound techniques [1,2,3]. These results are based on experiments conducted at room temperature. The principle[1], in essence, is to launch ultrasonic shear waves at the interface of a solid and a viscous fluid. The amplitude and phase of the reflected waves were correlated to the viscosity of the fluid.

Measurement of Viscosity in Liquids Using Reflection Coefficient: Phase Difference Method

Measurement of viscosity of fluids is a critical parameter in determining the state of the fluid (ie. edible products), and the state of the forming solid (ie. molten metals and glasses). Experiments to measure viscosity using ultrasound, have been carried out since as early as 1951 [1]. Ultrasound has potentially offered a non-invasive, in-line method of property and process monitoring [2,3]. Early research has demonstrated that viscosity measurement can be accomplished by ultrasound using different linear and nonlinear techniques [4]. This paper is devoted to furthering the technique called shear reflectance method [5].

Waveguide Sensor for Liquid and Slurry Properties

It is extremely important for operators of various chemical and manufacturing facilities to know the properties of the liquids and slurries they are processing. These processes can be found in the polymer, petrochemical, oil refinery, food, pharmaceutical, pulp and paper industries. Liquid and slurry property monitoring is also important in the processing of hazardous and radioactive wastes [1].

Viscosity Measurement with Laser Ultrasonics

In the previous year, results were presented in which the viscosity of calibration liquids were determined by measuring the reflection coefficient of laser generated shear waves. [1] The shear waves were launched with a pulsed Nd: YAG laser into an aluminum wedge and detected using a piezoelectric transducer. This year results are presented from a totally noncontact system, generating the shear waves with a pulsed laser and detecting the reflected shear waves with a laser interferometer. The design of the wedge was modified so that the shear waves are incident to the solid-liquid interface at nearly normal incidence. They reflect off this interface and are incident on the surface of detection at greater than the critical angle. This allows for the largest possible out-of-plane displacement, which can then be detected with the interferometer. This type of arrangement has been used with both aluminum and graphite wedges.

Shear Wave Wedge for Laser Ultrasonics

Ultrasonic shear waves are a useful tool for determining the mechanical properties of various materials. One example is the use of shear waves to measure viscosity. The viscosity can be determined from the shear wave reflection coefficient. The reflection coefficient from a solid-liquid interface is a function of the viscosity and density of the liquid, as well as the angle of incidence and the material properties of the solid. [1,2]

Drum Pressure Monitor

At many waste sites, transuranic (TRU), low-level, and mixed wastes are stored in 55-gallon drums. Many of these drums contain hazardous, organic wastes as well. Radiolysis or other physical or chemical processes may result in gaseous emissions inside these drums. When this happens the pressure within the drum will increase, sometimes to unacceptable levels. In more drastic cases, these emissions may produce flammable or explosive atmospheres (e.g., hydrogen from radiolysis). Currently regulatory procedures require that each drum be individually opened and inspected for the presence of hazardous organic waste. This situation will be dangerous for workers if either of the conditions described above exist (high pressure or flammable atmosphere). A non-intrusive technique that would detect any increase in pressure over ambient would alert workers of potential danger and greatly increase safety. Conversely, it would allow the segregation of suspect drums, and more rapid treatment of safe drums.

Integrated waveguide/thermocouple sensor for liquid properties

A torsional and longitudinal waveguide was introduced several years ago and shown to be effective for measuring various properties of liquids, including viscosity, density and temperature. The instrument is simply a specially constructed, thin rod (waveguide), one end of which is inserted into the liquid slurry. Torsional or extensional waves are generated in the rod, via a magnetostrictive mechanism, by passing a current through a coil which fits over the dry end of the rod. Liquid properties are correlated to different attributes of the waves (e.g., speed and amplitude) that travel down the rod and reflect off the end that is inserted into the liquid. Different properties of the material can be determined using waveguides of different cross-section. Noncircular rods are used to measure density, while viscosity is measured with circular rods. Since temperature affects these same wave attributes it would be desirable to have an independent measure of the temperature. This is accomplished by using a thermocouple sheath as the sensor part of the waveguide. In this way, the influence of temperature can be decoupled from the other properties of interest. In addition, the temperature is measured at the same point where the other properties of the liquid are being measured. The basic design of the sensor will be presented along with experimental results.

Wave Propagation in a Newtonian Fluid with Viscosity Gradients Profiles

Plane compressional wave propagation in a fluid is significantly affected by the shear viscosity of the fluid [1]. Several different theories have been developed [2,3,4] to understand effects of viscosity on wave propagation characteristics. Presence of concurring phenomena such as thermal conductive losses and molecular relaxations [5] has frurther complicated the study of wave propagation. In liquids however, the effect of thermal conductivity is not comparable to the viscous losses [1]. In such cases, it has been possible to associate viscosity with the wave propagation characteristics.