News + Publications

In many industrial applications and processes, developing a good understanding of the hydrodynamics at play is needed for optimization and future development. Measurement techniques, using either intrusive or nonintrusive methods, have a key role in building this understanding.
Multi-phase processes such as fluidized beds, gravity separators, mix boxes, and tailings treatment technologies involve visually opaque materials and components. In these situations, nonintrusive methods can offer crucial advantages.
Intrusive techniques are often less expensive and easier to build and maintain. Optical measurement techniques can be an effective tool when detection of voids or tracking of species is the main goal. However, quantitative measurement of local density is often inaccurate without precise calibration. Calibration can be particularly difficult due to the inconsistency of optical properties of particles with different material or size distribution.
X-ray and gamma attenuation-based instrumentation can be used to measure density in a nonintrusive manner. There is a wide variety of densitometers available, ranging from basic average density measurement in which no local information can be obtained, to more sophisticated tomographic techniques that provide local density profiles within the measurement volume. Electrical capacitance tomography (ECT) is another visualization method often employed for multi-phase measurements. The main downsides of these techniques are their relatively low spatiotemporal resolution, relatively high cost, and the necessity for physical access to the vessel surroundings, making their implementation at industrial scales difficult.
In a recent post and related whitepaper, we used x-ray imaging for flow characterization inside a fluidized bed column with a focus on the effects of bed internals on bulk density profiles. Bed internals (sheds, rods, beams) are often used to alter solids hydrodynamics and transport by enhancing or staging solids mixing. Intrusive measurement equipment such as probes can negatively impact bed hydrodynamics, as visualized using our x-ray equipment.