The paper presents an attempt to find the possibility of measuring high temperature properties of mould powder slags such as viscosity, break temperature, liquidus temperature during heating as well as solidification start and solidification end temperatures during cooing using ultrasonics. These powders are used in continuous casting of steel and the abnormality in their properties can impact the productivity and quality of the steel products. These properties are in general measured by high temperature rotational viscometers, hot stage microscopes and DTA instruments. Here, the fundamental flexural guided wave mode F(1,1) in a ceramic buffer rod was employed in experiments. The results show the possibility of measuring all the above properties in single experiment by measuring ultrasonic reflection factors during continuous heating and cooling of the mould powders. The advantage of the ultrasonic system is that it can be installed in the plant for online monitoring of these properties. The ultrasonically measured properties of the mould powders supplied by five different suppliers were compared with those measured by rotational viscometers and estimated by mathematical models. © 2011.

Krishnan Balasubramaniam

Department of Mechanical Engineering

Suresh Periyannan

BREAK TEMPERATURE

Continuous heating

Guided wave modes

High temperature

HOT STAGE

LIQUIDUS TEMPERATURE

MEASURED PROPERTIES

MELTING CHARACTERISTICS

MOULD POWDERS

Online monitoring

ROTATIONAL VISCOMETER

SOLIDIFICATION END

STEEL PRODUCTS

ULTRASONIC SYSTEM

Continuous casting

heating

Mathematical models

Molds

Powders

Slags

Solidification

Ultrasonics

Viscometers

Viscosity

Viscosity measurement

Steel castings

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Measurement of viscosity and melting characteristics of mould powder slags by ultrasonics

Ironmaking and Steelmaking

This paper reports on an ultrasonic waveguide sensor for liquid level measurements using three guided wave modes simultaneously. The fundamental wave modes longitudinal L(0,1), torsional T(0,1), and flexural F(1,1) were simultaneously transmitted/received in a thin stainless steel wire-like waveguide using a standard shear wave transducer when oriented at an angle of 45° to the axis of the waveguide. Experiments were conducted in non-viscous fluid (water) and viscous fluid (castor oil). It was observed that the flexural F(1,1) wave mode showed a change in both time of flight (due to the change in velocity and dispersion effects) and amplitude (due to leakage) for different levels (0-9 cm) of immersion of the waveguide in a fluid medium. For the same level of immersion in the fluid, the L(0,1) and the T(0,1) modes show only a relatively smaller change in amplitude and no change in time of flight. The experimental results were validated using finite element model studies. The measured change in time of flight and/or the shift in central frequency of F(1,1) was related to the liquid level measurements. Multiple trials show repeatability with a maximum error of 2.5% in level measurement. Also, by monitoring all three wave modes simultaneously, a more versatile and redundancy in measurements of the fluid level inside critical enclosures of processing industries can be achieved by compensating for changes in the fluid temperature using one mode, while the level is measured using another. This ultrasonic waveguide technique will be helpful for remote measurements in physically inaccessible areas in hostile environments. © 2019 Author(s).

Fulltext

Review of Scientific Instruments

Ultrasonic waveguide based level measurement using flexural mode F(1,1) in addition to the fundamental modes

Ultrasonic waveguide-based sensing, that permit robust measurements and sensing, is discussed in this paper. The use of ultrasonic guided waves has several advantages including remote measurements, multi-modal nature allowing for measurement of different parameters, small footprint, low cost, multi-point measurements on the same waveguide and most importantly robustness. These inherent qualities of ultrasonic waveguide-based sensing are particularly useful in industrial applications. One of the key applications that will be described will be the measurement of E and G moduli of materials as a function of temperature over a wide range of materials will be demonstrated. Knowing the moduli as a function of temperature, the measurement of physical properties such as temperature, rheology, fluid level, etc. of the surrounding fluid material can be accomplished using several embodiments of the waveguides using the fundamental wave modes such as L(0,1), T(0,1) and F(1.1). In addition, it will be shown that under sodium imaging in large plant conditions can be performed using ultrasonic waveguides using the A0 modes. © 2018 IEEE.

Proceedings of IEEE Sensors

Ultrasonic Waveguide Sensors for Measurements in Process Industries

This paper studies the propagation of ultrasound in spiral waveguides, towards distributed temperature measurements on a plane. Finite Element (FE) approach was used for understanding the velocity behaviour and consequently designing the spiral waveguide. Temperature measurements were experimentally carried out on planar surface inside a hot chamber. Transduction was performed using a piezo-electric crystal that is attached to one end of the waveguide. Lower order axisymmetric guided ultrasonic modes L(0,1) and T(0,1) were employed. Notches were introduced along the waveguide to obtain ultrasonic wave reflections. Time of fight (TOF) differences between the pre-defined reflectors (notches) located on the waveguides were used to infer local temperatures. The ultrasonic temperature measurements were compared with commercially available thermocouples. © 2017 Author(s).

AIP Advances

Multiple temperature sensors embedded in an ultrasonic “spiral-like” waveguide

This paper describes novel techniques for simultaneous measurement of temperatures at multiple locations using two configurations (a) a single transducer attached to multiple waveguides of different lengths (each with a single bend) and (b) single waveguide with multiple bends connected to single transducer. These techniques improve upon the earlier reported studies using straight waveguides, where the non-consideration of the effect of temperature gradients was found to be a major limitation. The range of temperature measurement is from room temperature to maximum utility temperature of the waveguide material. The time of flight difference of reflected ultrasonic longitudinal guided wave modes (L(0, 1)) from the bend, which is the reference signal, and another signal from the end of the waveguide, is utilized to measure the local temperature of the surrounding media. Finite element simulations were employed to obtain the appropriate dimensions and other design features of the multiple bent waveguide. This work is of interest to several industrial applications involving melters and furnaces. © 2016

Ultrasonic bent waveguides approach for distributed temperature measurement

Distributed temperature sensing has important applications in the long term monitoring of critical enclosures such as containment vessels, flue gas stacks, furnaces, underground storage tanks and buildings for fire risk. This paper presents novel techniques for such measurements, using wire in a spiral configuration and having special embodiments such a notch for obtaining wave reflections from desired locations. Transduction is performed using commercially available Piezo-electric crystal that is bonded to one end of the waveguide. Lower order axisymmetric guided ultrasonic modes were employed. Time of fight (TOF) differences between predefined reflectors located on the waveguides are used to infer temperature profile in a chamber with different temperatures. The L(0,1) wave mode (pulse echo approach) was generated/received in a spiral waveguide at different temperatures for this work. The ultrasonic measurements were compared with commercially available thermocouples. © 2017 Author(s).

AIP Conference Proceedings

Distributed temperature sensing using a SPIRAL configuration ultrasonic waveguide

This paper describes an experimental procedure using ultrasonic waves propagating in a rod to simultaneously measure the viscosity and temperature of melts at high temperatures using a very small amount of sample and without any mechanical rotating equipment. This method has applications in laboratory tests as well as for process monitoring in industries. A refractory material is used as buffer rod in the experiment to transfer the ultrasonic vibrations from a piezoelectric transducer into the melt, which is water cooled to protect the transducer from high temperatures. The sensor is based on the effect of melt viscosity on ultrasonic guided wave reflections from the solid-fluid interface. The difference in the time of flight of the ultrasonic wave in the buffer rod at two different temperatures is used to measure the temperature. The results from the measurement of melt viscosity using the proposed method, on three different glass samples, are in agreement with the values provided by the National Institute of Standards and Technology, USA. This method offers advantages in reduction in the amount of sample, cost, complexity in experiments, experimental time. © 2008 Elsevier B.V. All rights reserved.

Journal of Materials Processing Technology

Viscosity measurements of melts at high temperatures using ultrasonic guided waves

Discussiones Mathematicae. Differential Inclusions, Control and Optimization

Existence of solutions for second order stochastic differential inclusions in Hilbert spaces

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

ISIJ International

Density Measurements of Mould Flux Slags by Electrostatic Levitation Method

A Semi-empirical Model for Viscosity Estimation of Molten Slags in CaO–FeO–MgO–MnO–SiO2 Systems

Journal	Ironmaking and Steelmaking
ISSN	03019233
Open Access	No