On-line Characterisation of Particulate Suspensions Using a Multi-sensor Approach

Executive Summary

Work is reported of relevance to the pharmaceutical, chemical, mineral and other manufacturing processes against our objectives of developing and demonstrating the use of multi-sensors for mapping of microstructure and flow properties of concentrated suspensions and dispersions. The goal is to use this information for control of particulate product formulation in which on-line measurement enables new or more consistent products to be manufactured. The measurement tools used have included electrical conductivity tomography, X-ray tomography and photography and ultrasound measurements. Principal achievements of the research and team are reported under the following headings:

Software Tools

• Development of a new algorithm for enhances data analysis and image reconstruction, that is more robust to fluctuations in the background electrical properties of the process mixture.
• Computation of local changes in axial and radial solid concentration profiles.
• Measurement of velocity of features/flow structures in the mixture.
• An example case study for hydraulic conveying.

Instrument and Technique Development

• Simpler (single) electrode arrays for pipe-based measurements.
• Alternative impedance measurements yielding absolute images for paste extrusion in barrel and die.
• Demonstration of 3d imaging and reconstruction from a limited electrode data set in a narrow bore die.
• Use of X-ray microtomography with a digital simulation approach to enable prediction of properties of complex structure materials.

Model Validation Case Studies

Here the goal has been to use the multi-sensor measurement method to validate models. Two examples have been progressed-

• Slurry hydrotransport modelling and measurement using electrical tomography (above)
• Slurry transport within a small diameter hydrocyclone, comparing CFD and tomographic measurement (electrical and XC-ray photographs)

The forward plan for 2002/3 is outlined with our focus on measurement and quantification of product microstructure in particulate materials and products.