Hugh P. Rice

Measuring particle concentration in multiphase pipe flow using acoustic backscatter: generalization of the dual-frequency inversion method.

A technique that is an extension of an earlier approach for marine sediments is presented for determining the acoustic attenuation and backscattering coefficients of suspensions of particles of arbitrary materials of general engineering interest. It is necessary to know these coefficients (published values of which exist for quartz sand only) in order to implement an ultrasonic dual-frequency inversion method, in which the backscattered signals received by transducers operating at two frequencies in the megahertz range are used to determine the concentration profile in suspensions of solid particles in a carrier fluid. To demonstrate the application of this dual-frequency method to engineering flows, particle concentration profiles are calculated in turbulent, horizontal pipe flow. The observed trends in the measured attenuation and backscatter coefficients, which are compared to estimates based on the available quartz sand data, and the resulting concentration profiles, demonstrate that this method has potential for measuring the settling and segregation behavior of real suspensions and slurries in a range of applications, such as the nuclear and minerals processing industries, and is able to distinguish between homogeneous, heterogeneous, and bed-forming flow regimes.

Development of a real-time acoustic backscatter system for solids concentration measurement during nuclear waste cleanup

The measurement of the concentration of solid particles in suspension without physical sampling is a necessary tool for the nuclear industry involved with cleanup of a significant quantity of legacy waste in the form of sludge. This paper presents the work of a project to develop acoustic instrumentation for the in-situ characterization of such sludge. The measurement principle and signal processing employed is presented along with the design of a custom acoustic instrument for deployment in nuclear and industrial environments. The paper presents experimental results demonstrating the ability of the technique for the online measurement of mass concentration in a suspension of glass power in water.

Large-scale trials of a real-time acoustic backscatter system for solids concentration measurement during nuclear waste cleanup

Real time in situ characterisation of solids concentration would aid operational understanding and improve efficiency in many industrial systems. This is especially true in the processing of legacy nuclear wastes where hazardous material is encountered. Acoustic methods have been previously demonstrated for the measurement of concentration in solid-liquid systems at a small scale. This study explores the use of the ultrasound array research platform (UARP) for backscatter measurements of concentration at a large scale in a dynamic settling system. The theory of acoustic measurement of solids concentration is described for both backscatter based attenuation and backscatter power methods. Acoustic based backscatter power and attenuation measurements are compared to laboratory analysed samples. Ultrasonic solids concentration analysis is shown to reveal flow dynamics within the settling tank.

Transport and Deposition Properties of Model Slurries of One and Two Particle Species

The UK nuclear industry has in its inventory legacy waste in the form of complex, polydisperse and “polydense” suspensions, slurries and sludges in a variety of storage and transport vessels. This waste has been difficult to characterise because of radioactivity and limited accessibility, and conditioning and disposal of the waste presents a continuing challenge. In addition, the mechanisms by which very dense particles are transported in pipes are not well understood. Our objectives are to investigate the effect of mono- and bidisperse suspensions with a range of particle sizes and densities on the turbulence characteristics, transport and settling behaviour of slurries that are chosen to be analogues of those found on nuclear sites. Two versatile slurry pipe-flow loops of different diameters have been commissioned which can be operated over a large range of Reynolds numbers and are amenable to ultrasonic measurement methods. Details of the flow loops are presented, including optimisation studies. Results are presented for a variety of particle characterisation studies that have been performed on the particle species that form the suspensions, along with mean and RMS (root mean square) velocity profiles over a range of Reynolds number and particle concentration. In particular, the effect of particle concentration on the formation of settled beds, and mean flow velocity and turbulence characteristics has been investigated.© 2011 ASME