Effect of hydrodynamic multiplicity on trickle bed reactor performance

• Published in: AIChE journal Vol. 54; no. 1; pp. 249 - 257
• Main Authors: van der Merwe, Werner, Nicol, Willie, Al-Dahhan, Muthanna H
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 2008; Wiley Subscription Services; American Institute of Chemical Engineers
• Subjects: Applied sciences; Catalysis; Catalysts; Catalytic reactions; Chemical engineering; Chemical reactions; Chemistry; Exact sciences and technology; Flow rates; Fluid dynamics; Fluidized bed reactors; General and physical chemistry; Heat and mass transfer. Packings, plates; Hydrodynamics of contact apparatus; Mass transfer; multi-phase flow; Reactors; Styrene; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; trickle bed reactors; Holdup; Trickle bed reactor; Wetting; Pressure drop; Trend analysis; Hydrodynamics; multi-phase flow; Hydrogenation; Catalyst; Hysteresis; Mass transfer; trickle bed reactors
• ISSN: 0001-1541; 1547-5905
• DOI: 10.1002/aic.11360

Multiple hydrodynamic states in trickle bed reactors have been the subject of numerous hydrodynamic investigations. The extent of variation in the hydrodynamic parameters (like holdup and pressure drop) is large and this variation can be expected to have a significant impact on the conversion in a reaction system. This study presents reaction data for α-methyl styrene hydrogenation in a trickle bed reactor over a range of conditions that include gas and liquid limitations. It is seen that liquid flow rate variation induced hysteresis has a large impact on the conversion. For gas-limited reactions, the upper branch of the pressure drop hysteresis loop has a higher conversion than the lower branch at the same linear fluid velocities and catalyst weight, while for liquid-limited reactions the lower branch has a higher conversion than the upper branch (the difference in productivity being up to 20%). These trends cannot be explained by differences in wetting efficiency. Instead, it is proposed that for this system the gas-liquid mass transfer rate is the limiting step in gas-limited reactions, while the liquid-solid mass transfer rate is the limiting step in liquid-limited reactions. © 2007 American Institute of Chemical Engineers AIChE J, 2008