Intrusive probes in riser applications

• Published in: AIChE journal Vol. 63; no. 12; pp. 5361 - 5374
• Main Authors: Cocco, Ray A., Karri, S.B. Reddy, Knowlton, Ted M., Findlay, John, Gauthier, Thierry, Chew, Jia Wei, Hrenya, Christine M.
• Format: Journal Article
• Language: English
• Published: New York American Institute of Chemical Engineers 01-12-2017; Wiley
• Subjects: Catalytic cracking; Computational fluid dynamics; Computer applications; Computer simulation; Cracking (chemical engineering); Fiber optics; fiber‐optic probe; Fluid catalytic cracking; Fluid dynamics; Fluid flow; Fluid mechanics; fluidized bed; Fluidized beds; Hydrodynamics; intrusive probe; local hydrodynamics; Mechanics; Optical fibers; Particulates; Physics; pitot tube; Pressure drop; Probes; Risers; intrusive probe; fiber-optic probe; pitot tube; fluidized bed; local hydrodynamics
• ISSN: 0001-1541; 1547-5905
• DOI: 10.1002/aic.15892

Many of the probes used to understand hydrodynamics in circulating fluidized bed risers intrude into the environment they are measuring, although assumptions are typically asserted that the intrusive probes do not affect the data collected. This could be a poor assumption in some cases and conditions. We found that intrusive fiber‐optic probe measurements consistently mis‐predicted the solids concentration compared to the nonintrusive pressure drop measurements outside the fully developed flow region of a riser containing fluid catalytic cracking catalyst or glass bead particles. The discrepancy was sensitive to superficial gas velocity, solid circulation rate, probe position, and flow direction. Barracuda VR™ computational fluid dynamics simulations confirmed this, and indicated that particle momentum was lost at the leading edge of the probe and particles were spilling over to the probe tip. Accordingly, new probe designs were proposed to mitigate the intrusiveness of a fiber‐optic probe for more accurate characterization. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5361–5374, 2017