Hydrodynamics of cocurrent two-phase flows in slanted porous media-Modulation of pulse flow via bed obliquity

Hydrodynamics and Reaction Performances of Multiphase Reactors for Marine Applications – A Review

Hydrodynamics and (catalytic & non-catalytic) reaction [high-pressure hydrodesulfurization; Fischer-Tropsch synthesis; CO2-monoethanolamine (MEA) absorption; simultaneous CO2 and H2S absorption in MEA; CO2 thermal desorption, enzymatic CO2 hydration] performances of trickle-bed and packed-bed column reactors subjected to static inclination, rolling (symmetrical/asymmetrical externally-generated reactor oscillations) and heaving motions were analyzed via detailed dynamic 3-D models which couple the macroscopic volume-averaged momentum, mass, energy and species balance equations in the liquid/gas phases with diffusion/chemical reaction inside the catalyst particles, enzyme washcoat or liquid film near the gas-liquid interface. Axial symmetry breakdown once the packed bed systems become inclined inflicts noticeable reductions of the reactor (or scrubber) performances. Only the performance of Fischer-Tropsch synthesis in the presence of water-gas shift reaction increases slightly with the increase of trickle-bed reactor inclination because of facile uptake of reactants in the key reactions from the gas phase while a fraction of valuable CO can be forwarded in water gas-shift reaction. For most of the reactions examined, the reactor performance is negatively impacted in asymmetric oscillating multiphase reactors with Fischer-Tropsch synthesis as an exception owing to the presence of water-gas shift reaction the performance of which is slightly improved. This performance deterioration/enhancement is maximal for the reactor moving between vertical and an inclined position when the time-dependent performance waves develop around the steady-state solution of the mid-inclination angle. The oscillatory reactor performance moves towards the steady-state solution of the vertical state when the asymmetry between the two inclined positions dwindles. Symmetric oscillating and heaving trickle-bed and packed-bed column reactors generate an oscillatory performance around the steady-state solution of vertical state which is affected by the amplitude and period of the angular and heaving motions of the vessel.

Al-Dahhan M. Assessing the Feasibility of Optical Probe in Phase Holdup Measurements and Flow Regime Identification

Despite the hydrodynamics of trickle beds experiencing pilot size, on the contrary, the possibility of measuring hydrodynamic parameters locally and for large scale and finding an indicator to pinpoint the flow regime from trickling to pulsing remains obscure, to assess the feasibility of getting such information the reactor bed was randomly packed with equal-sized spherical beads of 3 mm diameter. Gas and liquid holdup measurements and flow regime identification were achieved at various flow conditions from trickling to the pulsing regime by an optical probe method using time series processing method. This method is shown to be simple and efficient provides quantitative information about the gas and liquid holdup variation in different flow regime. The various experimental results were compared to available literature models and correlations for confrontation and recommendations. The trickle-to-pulse flow transition boundary shifted towards higher gas and liquid superficial velocities, aligning with the findings on a variation of holdup along the axial direction confirmed to broaden the trickle flow domain.

[Correction added after online publication June 26, 2015: To unify the adjective everywhere in this manuscript, optic fiber probe was changed to optical probe.]