Magnetic resonance imaging of gas–solid fluidization with liquid bridging

• Published in: AIChE journal Vol. 64; no. 8; pp. 2958 - 2971
• Main Authors: Boyce, C. M., Penn, A., Pruessmann, K. P., Müller, C. R.
• Format: Journal Article
• Language: English
• Published: New York American Institute of Chemical Engineers 01-08-2018
• Subjects: Bubbles; Bubbling; Channeling; Computational fluid dynamics; Computer applications; Fluid flow; Fluid mechanics; Fluidization; Fluidized beds; Hydrodynamics; Liquid bridges; liquid bridging; Magnetic resonance imaging; Mathematical models; NMR; Nuclear magnetic resonance; Organic chemistry; Resonance; Surface tension; Velocity; Velocity distribution; Viscosity; Wetting
• ISSN: 0001-1541; 1547-5905
• DOI: 10.1002/aic.16036

Magnetic resonance imaging is used to generate snapshots of particle concentration and velocity fields in gas–solid fluidized beds into which small amounts of liquid are injected. Three regimes of bed behavior (stationary, channeling, and bubbling) are mapped based on superficial velocity and liquid loading. Images are analyzed to determine quantitatively the number of bubbles, the bubble diameter, bed height, and the distribution of particle speeds under different wetting conditions. The cohesion and dissipation provided by liquid bridges cause an increase in the minimum fluidization velocity and a decrease in the number of bubbles and fast particles in the bed. Changes in liquid loading alter hydrodynamics to a greater extent than changes in surface tension or viscosity. Keeping U/Umf at a constant value of 1.5 produced fairly similar hydrodynamics across different wetting conditions. The detailed results presented provide an important dataset for assessment of the validity of assumptions in computational models. © 2017 American Institute of Chemical Engineers AIChE J, 64: 2958–2971, 2018