Hydrodynamics of gas-liquid co-current up-flow in oscillating packed beds for offshore marine applications

Significance Statement

Gas-liquid co-current up-flow packed beds are normally applied as reactors and multiphase contactors in chemical processes that necessitate a contact between solid, liquid and gas phases. Alkylation, hydrogenation, wastewater treatment and oxidation are a few processes that implement this type reactor owing to cheap operations and simple construction. Above all, high liquid residence time, superior interphase heat and mass transfers are also a few benefits that come with co-current up-flow packed bed reactors.

However, complexities in hydrodynamics of these reactors and the need for reliable designs and scale-up for industrial applications have attracted significant research works. While some studies focus on experimental methods to analyze the hydrodynamics such as bubble characteristics, flow regime, back mixing and pressure drop, a few have focused on the development of mathematical models to approximate these hydrodynamic parameters.

The effects of ship rotational as well as translational oscillations on the hydrodynamic characteristics of co-current up-flow packed beds have not been investigated. Therefore, researchers led by Professor Faïçal Larachi from Laval University in Canada, in their work, offered some insights into the hydrodynamic characteristics of up-flow packed bed reactors for off-shore floating platforms. They examined these characteristics in terms of liquid saturation, pulse flow regime, pressure drop, and phase distribution using hexapod motion simulator and wire mesh sensors. Their work is published in peer-reviewed journal, Chemical Engineering Science.

For laboratory-scale hydrodynamic analyses, the authors did the experiments using water and air operated in a co-current up-flow mode. They adopted a column packed with glass beads positioned on a hexapod ship motion simulator that was able to emulate single as well as multiple degrees of freedom; both rotational and translational. They embedded in the bed wire mesh sensors in order to record variations in instantaneous liquid saturation and characterize their flow characteristics during bed excitations.

The authors used Aris’s two-point deflection and tracer signal analysis methods to determine the Peclet number. Also, residence time distribution analysis enabled them to determine the liquid mean residence time.

They observed that the column deviation from the mean position greatly affected the hydrodynamics of the packed bed operating in an up-flow mode. Oscillations initiated noticeable effects on the bed gas-liquid distribution and pressure drop. While tilting motions caused significant oscillations in the uniformity factors and pressure drops, the non-tilting motions augmented the parameters with minor fluctuations only. When they increased the tilt angle of the stationary bed, they recorded a drop in the Peclet Number and augmented liquid residence time owing to the creation of gas-liquid disengagement zones.

Tilting oscillations limited gas-liquid interactions based on gravity driven flows inside the beds that resulted in a delay in the initiation of pulse flow regime. Also, a rolling period of about 20 seconds displayed a pulse flow regime which coincided with the straightening of the column in the course of oscillations. Liquid velocity intensified the gas-liquid interaction which led to the formation of even more pulses for roll and pitch motions.

https://advanceseng.com/wp-content/uploads/2017/04/Hydrodynamics-of-gas-liquid-co-current-up-flow-in-oscillating-packed-beds-for-offshore-marine-applications-Advances-in-Engineering.png

About The Author

Prof. Faïçal Larachi research aims at devising micro/multifunctional processes and materials in the areas of (bio-)energy, mineral resources and the environment with an emphasis on upgrading/conversion of unconventional fossil energy/residual biomass, implementing GHG mitigation through CO2 capture/storage and solving aqueous and interfacial chemistry issues in mineral beneficiation. He has co-authored 350+ journal papers, 3 books and 20+ plenary/keynote lectures in international conferences.

He served as Associate Editor for the Canadian Journal of Chemical Engineering, and as Member of the Editorial or Advisory Boards for the journals Industrial & Engineering Chemistry Research, Chemical Engineering & Processing: Process Intensification, and Indian Chemical Engineer.

His research contributions have been recognized in various ways, including the Tier 1 Canada Research Chair endowment, twice-awardee of the NSERC Discovery Acceleration Supplement, recipient of the 2012 UL Research Summa Award, and selected twice as “Carbon Capture Sequestration” Leaders in Canada by the Carbon Capture Journal. Prior to joining Laval University as a faculty, he obtained a chemical engineering doctoral degree from Institut National Polytechnique at Université de Lorraine (France), and held a post-doctoral position at École Polytechnique of Montréal. He was visiting professor with Total (France), the Institut Français du Pétrole (IFPEN, France) and the Consortium de recherche minérale (COREM, Canada) where he spent two sabbatical years.

About The Author

Amir Motamed Dashliborun received his B.S. and M.Sc. degrees in Chemical Engineering from University of Tehran, Iran in 2010 and 2012, respectively. From 2012 to 2013 he worked as process engineer with Process Design and Simulation Research Center at University of Tehran. In 2014 he joined the Department of Chemical Engineering at Université LAVAL, Canada as a Ph.D. candidate. His Ph.D. research studies focuses on performance of multiphase packed-bed reactors on offshore floating platforms integrating both experimental and modeling.

The Natural Sciences and Engineering Research Council of Canada and the Canada Research Chair on Sustainable Energy Processes and Materials support financially this project. In 2015 he was invited as a guest scientist by the Institute of Fluid Dynamics at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) to pursue a part of his Ph.D. project.

About The Author

Dr. Markus Schubert obtained his Diploma in Process Engineering from Technische Universität Dresden (Germany) in 2003 and his Ph.D. in Chemical Engineering from Technische Universität Dresden in 2007. Following Ph.D., he joined Helmholtz-Zentrum Dresden-Rossendorf (Germany) as a postdoctoral researcher in 2007. 2008 to 2009 he joined the Department of Chemical Engineering at Université LAVAL (Québec City, Canada) as a postdoctoral fellow sponsored by the Canadian Government. Since 2009, he has been a research associate at the Institute of Fluid Dynamics at Helmholtz-Zentrum Dresden-Rossendorf (Germany).

His research focus is on multiphase reactors, novel reactor concepts, process intensification and tomographic imaging. He has published over 60 journal papers in peer-reviewed journals. In 2012, he was selected by the European Research Council (ERC) for the prestigious ERC Starting Grant for a project dealing with high-speed tomographic imaging of multiphase flows.

Reference

Amir Motamed Dashliborun1, Faïçal Larachi1, and Markus Schubert2. Hydrodynamics of gas-liquid co-current up-flow in oscillating packed beds for offshore marine applications. Chemical Engineering Science Available online 25 December 2016.

Show Affiliations
  1. Department of Chemical Engineering, Laval University, Québec, QC G1V 0A6, Canada
  2. Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraβe 400, 01328 Dresden, Germany

 

Go To Chemical Engineering Science