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Optimization of the UVP+PD rheometric method for flow behavior monitoring of industrial fluid suspensions
Appl. Rheol. 22:4 (2012) 42760 (11 pages) ►
Ultrasonic Velocity Profiling (UVP) is a powerful technique for velocity profile measurements in research and engineering applications as it is the only available method that is cost-effective, relatively easy to implement and applicable to opaque fluid suspensions, which are frequently found in industry. UVP can also be combined with Pressure Drop (PD) measurements in order to obtain rheological parameters of non-Newtonian fluids by fitting theoretical rheological models to a single velocity profile measurement. The flow properties of complex fluids are almost exclusively obtained today using commercially available instruments, such as conventional rotational rheometers or tube (capillary) viscometers. Since these methods are time-consuming and unsuitable for real-time process monitoring, the UVP+PD methodology becomes a very attractive alternative for in-line flow behavior monitoring as well as quality control in industrial applications. However, the accuracy of the UVP+PD methodology is highly dependent on the shape and magnitude of the measured velocity profiles and there are still a few problems remaining with current instrumentation and methods in order to achieve the robustness and accuracy required in industrial applications. The main objective of this research work was to optimize an UVP+PD system by implementing new transducer technology and signal processing techniques for more accurate velocity profile measurements as well as rheological characterization of complex fluids under industrial/realistic conditions. The new methodology was evaluated in two different pipe diameters (22.5 and 52.8 mm) and tested with three different non-Newtonian fluids in order to obtain a wide range of rheological parameters. Results were also compared to conventional rotational rheometry and tube viscometry. It was found that rheological parameters obtained from accurate velocity data across the pipe radius, especially close to pipe walls where the velocity gradient is high, showed better agreement to conventional rheometry than when compared to results obtained using profiles measured with conventional UVP instrumentation and commercial software (Met- Flow SA Version 3.0). The UVP+PD method is now more robust and accurate. The main challenge remaining is to successfully implement a complete non-invasive system in industrial processes that is able to achieve real-time and accurate complex flow monitoring of non-Newtonian fluid suspensions.► Cite this publication as follows:
Kotze R, Wiklund J, Haldenwang R: Optimization of the UVP+PD rheometric method for flow behavior monitoring of industrial fluid suspensions, Appl. Rheol. 22 (2012) 42760.
Reinhardt Kotze, Rainer Haldenwang, Paul Slatter
Rheological characterisation of highly concentrated mineral suspensions using an Ultrasonic Velocity Profiling with combined Pressure Difference method
Appl. Rheol. 18:6 (2008) 62114 (10 pages) ►
The rheological behaviour of non-Newtonian, highly concentrated and non-transparent fluids used in industry have so far been analysed using commercially available instruments, such as conventional rotational rheometers and tube viscometers. When dealing with the prediction of non-Newtonian flows in pipes, pipe fittings and open channels, most of the models used are empirical in nature. The fact that the fluids or slurries that are used normally are opaque, effectively narrows down the variety of applicable in-line rheometers even further, as these instruments are normally based on laser or visible light techniques, such as Laser Doppler Anemometry. In this research, an Ultrasonic Velocity Profiling technique (UVP), in combination with a pressure difference (PD) measurement, was tested to provide in-line measurement of rheological parameters. The main objective of this research was to evaluate the capabilities of the UVP-PD technique for rheological characterisation of different concentrations of non-transparent non-Newtonian slurries. Kaolin, bentonite, Carboxymethyl Cellulose (CMC) and water solutions were used as model non-Newtonian mining slurries. Results determined by the UVP-PD method were compared with results obtained by off-line rheometry and in-line tube viscometry. The agreement between the UVP-PD method, tube viscometry and conventional rheometry was found to be within 15 % for all of the highly concentrated mineral suspensions investigated over a given range of shear rates.This method, if used in combination with a pressure difference technique (PD), has been found to have a significant potential in the development process of new in-line rheometers for process control within the mining industry.► Cite this publication as follows:
Kotze R, Haldenwang R, Slatter P: Rheological characterisation of highly concentrated mineral suspensions using an Ultrasonic Velocity Profiling with combined Pressure Difference method, Appl. Rheol. 18 (2008) 62114.
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