Pressure Drop and Mass Transfer Studies in Liquid Fluidized Beds

2006 ◽  
Author(s):  
Bhagavatula Venkata Ramana Murthy
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Liquid Velocity ◽  
Water System ◽  
Solid Particles ◽  
Sugar Water ◽  
Minimum Fluidization Velocity ◽  
Liquid Systems ◽  
Mass Transfer Studies ◽  
Solid Liquid

Fluidized beds are widely used in industries for mixing solid particles with liquids as the solid is vigorously agitated by the liquid passing through the bed and the mixing of the solid ensures that there are practically no temperature gradients in the bed even with exothermic or endothermic reactions (Mixing and the segregation in a liquid fluidized of particles with different sizes and densities", The Canadian Journal of Chemical Engineering, 1988). The violent motion of the solid particles also gives high heat transfer rates to the wall or to cooling tubes immersed in the bed. Because of the fluidity of the solid particles, it is easy to pass solid from one vessel to another. In the present experimental work, the relative density between solid and liquid phases on pressure drop under fluidized condition has been studied using the solid-liquid systems namely, glass beads-water, glass beads-kerosene, plastic beads-kerosene and diamond sugar-kerosene. Pressure drop - liquid velocity and void fraction - liquid velocity relationships have been found for all the mentioned solid-liquid systems under fluidized condition and results have been noted. The effect of the nature of the fluid on the minimum fluidization velocity and the pressure drop has been studied. In addition to the pressure drop studies, mass transfer studies have also been conducted with diamond sugar-water system with and without fluidization and results have been obtained. In addition to these, comparison of bed voidage, pressure drop and minimum fluidization velocity between denser and lighter liquids have been studied and the results have been obtained. Also, the value of rate of mass transfer with fluidization is compared that without fluidization for diamond sugar-water system and the results have been obtained.

Analysis of Hydrodynamics and Mass Transfer of Gas-Liquid and Liquid-Liquid Taylor Flows in Microchannels

2019 ◽  
pp. 1-49
Author(s):  
Rufat Abiev
Keyword(s):  
Mass Transfer ◽  
Point Of View ◽  
Process Conditions ◽  
Two Phase ◽  
Physical Point ◽  
Micro Channels ◽  
Liquid Systems ◽  
Simplifying Assumptions ◽  
Liquid Flows ◽  
Solid Liquid

Analysis of hydrodynamics and mass transfer Taylor flows in micro channels of both gas-liquid and liquid-liquid systems on the basis of classical theoretical approach with some simplifying assumptions was performed. Results of theoretical analysis for description of hydrodynamic parameters and mass transfer characteristics were confirmed by comparison with the author's own and available in literature experimental data. It was shown that the main parameters of two-phase Taylor flows could be quite precisely described theoretically: mean bubble/droplet velocity, liquid film thickness, real gas holdup (which is always smaller than so-called dynamic holdup), pressure drop. Peculiarities of liquid-liquid flows compared to gas-liquid Taylor flows in capillaries are discussed. Wettability effect on hydrodynamics was examined. Tools of mass transfer intensification of gas-liquid and liquid-liquid Taylor flow in micro channels are analyzed. Three-layer model for heat and mass transfer has been proposed and implemented for the case of solid-liquid mass transfer for gas-liquid Taylor flows; optimal process conditions for this process are found theoretically and discussed from physical point of view.

scholarly journals Oscillatory flow reactors for synthetic chemistry applications

2020 ◽  
Vol 10 (3) ◽  
pp. 475-490 ◽  
Author(s):  
Pauline Bianchi ◽  
Jason D. Williams ◽  
C. Oliver Kappe
Keyword(s):  
Mass Transfer ◽  
Oscillatory Flow ◽  
Flow Reactor ◽  
Plug Flow ◽  
Operating Conditions ◽  
Solid Particles ◽  
Flow Reactors ◽  
Liquid Systems ◽  
Suspend Solid ◽  
Biphasic Systems

Abstract Oscillatory flow reactors (OFRs) superimpose an oscillatory flow to the net movement through a flow reactor. OFRs have been engineered to enable improved mixing, excellent heat- and mass transfer and good plug flow character under a broad range of operating conditions. Such features render these reactors appealing, since they are suitable for reactions that require long residence times, improved mass transfer (such as in biphasic liquid-liquid systems) or to homogeneously suspend solid particles. Various OFR configurations, offering specific features, have been developed over the past two decades, with significant progress still being made. This review outlines the principles and recent advances in OFR technology and overviews the synthetic applications of OFRs for liquid-liquid and solid-liquid biphasic systems.

Mass Transfer Studies in a Novel Perforated Plate Bubble Column

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
S. Dhanasekaran ◽  
T. Karunanithi
Keyword(s):  
Mass Transfer ◽  
Liquid Velocity ◽  
Bubble Column ◽  
Perforated Plate ◽  
Gas Velocity ◽  
Plate Spacing ◽  
Mass Transfer Studies ◽  
Superficial Gas Velocity ◽  
Superficial Liquid Velocity

This investigation reports the experimental and theoretical results carried out to evaluate the volumetric mass transfer coefficient (kLa) in a novel hybrid rotating and reciprocating perforated plate bubble column. Countercurrent condition is performed. kLa is studied by the absorption of oxygen from air into deoxygenated water at room temperature (27 ± 1°C). Effects of agitation level, superficial gas velocity, superficial liquid velocity and plate spacing on kLa were analyzed and found to be significant. With an increase in agitation level at a constant superficial gas and liquid velocities, the breakage process of gas bubbles starts to be more pronounced and intensive oxygen mass transfer occurs. Hence, kLa increases sharply. kLa increases with an increase in superficial gas velocity, due to higher gas holdup and the enhanced breakup of bubbles. Similarly, kLa increases with an increase in superficial liquid velocity and the effect is found to be significant. When plate spacing is decreased (by increasing the number of plates), it is observed that the kLa increases at higher superficial gas velocity and agitation level. Correlation is developed for the determination of kLa and found to concur with experimental results. This correlation can be used for the determination of kLa for this hybrid column with 95% accuracy within the range of variables investigated in this present study.

The Effect of Solid Surface Roughness on Dynamic Contact Angles in Solid-Liquid-Liquid Systems

2002 ◽  
Author(s):  
Dandina N. Rao ◽  
Hussain H. Radwani
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Solid Surface ◽  
Water System ◽  
Dynamic Contact ◽  
Contact Angles ◽  
Solid Surfaces ◽  
Liquid Systems ◽  
L Systems ◽  
Solid Liquid

The engineering applications of spreading and adhesion phenomena involving fluids on solids are numerous. The adhesive and spreading interactions at the solid-fluid interfaces are well characterized by dynamic contact angles. This study reports on the results of an experimental investigation into the effect of solid surface roughness on dynamic contact angles in solid-liquid-liquid (S-L-L) systems. The experiment involved the use of Wilhelmy Plate apparatus to measure adhesion tension (which is the product of interfacial tension and cosine of the contact angle between the liquid-liquid interface and the solid surface), the DuNuoy tensiometer to measure the liquid-liquid interfacial tension, and a profilometer to characterize the roughness of the solid surfaces used. The components of the solid-liquid-liquid systems studied consisted of: (i) smooth glass, roughened quartz and an actual rock surface for the solid phase, (ii) normal-hexane and deionized water as the two immiscible liquid phases. The dynamic contact angles (advancing and receding angles) of the three-phase (rock-oil-water) system provide essential information about the wettability of petroleum resrvoirs. The wettability of a reservoir is an important parameter that affects oil recovery in primary, secondary, and enhanced recovery operations [1]. Contact angle measurements on smooth surfaces are generally used to characterize reservoir wettability. However pore surfaces within reservoir rocks are essentially rough and hence it is important to determine the effect of such roughness on measured contact angles. There is very little information in the open literature on the effect of surface roughness on dynamic contact angles in S-L-L systems. In the present work, four levels of roughness of solid surfaces of similar mineralogy (quartz and glass) were tested in hexane-deionized water fluid pair. The advancing and receding contact angles measured at ambient conditions were analyzed for wettability effects. It was found that as surface roughness increased, the dynamic contact angles also increased. The wettability of the rock-oil-water system shifted from weakly water-wet for the smooth glass to intermediate-wet for the roughened surface. The general trends observed in our study were found to be in good agreement with other published results. However, the generally held notion of increasing contact angle hysteresis with increasing roughness appears to be incorrect in solid-liquid-liquid systems.

Hydrodynamic Behaviour and Mass Transfer Performance of SiC Foam

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Julien Leveque ◽  
David Rouzineau ◽  
Michel Prevost ◽  
Michel Meyer
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Water System ◽  
Theoretical Plate ◽  
Specific Area ◽  
Ceramic Foam ◽  
Transfer Performance ◽  
Hydrodynamic Behaviour ◽  
F Factor ◽  
Total Reflux

This work presents an experimental study of hydrodynamic behaviour and mass transfer performance of ceramic foam (SiC) as column packing. Voidage of the foam studied is of 91% with 640 m2/m3 specific area and 5 PPI. Hydrodynamics experiments are realised with air-water system in counter current in a 150 mm diameter column with a packing height of one meter. Parameters studied are pressure drop for dry and wet packing, flooding and liquid hold-up. Total reflux experiments with n-heptane/cyclohexane mixture were carried out in a distillation column at atmospheric pressure to study mass transfer by determination of HETP (Height Equivalent to Theoretical Plate). The performance in terms of pressure drop per unit height and flooding are quite lower in comparison with classical packings of distillation. The pressure drop obtained is about few millibars per meter (0-10 mbar.m-1) for F-Factor from the range of 0 to 1 and liquid superficial velocities from 1 to 10 m3m-2h-1. Liquid hold-up values, measured in the same range of flow, are in a range of 5 to 10%. The possible application of foam as a packing for distillation is so demonstrated.

scholarly journals Absorption in a three-phase fluidized bed I: Hydrodynamic investigations

2003 ◽  
Vol 57 (7-8) ◽  
pp. 326-329 ◽  
Author(s):  
Srdjan Pejanovic
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Gas Flow ◽  
Minimum Fluidization Velocity ◽  
Bed Height ◽  
Three Phase ◽  
Height Increase ◽  
Improve Mass Transfer

The hydrodynamic properties of a three phase fluidized bed with low density inert spherical packing, fluidized by the interaction of a gas flowing upwards and a liquid flowing downwards through the column, were investigated. It was found that the pressure drop, liquid hold up and dynamic bed height increase with both increasing liquid and gas flow rate. While the dynamic bed height and minimum fluidization velocity remain unchanged, both the pressure drop and liquid hold up increase with increasing density of the packing. Therefore, an increase in packing density causes more intensive mass transfer between the fluid phases than packed columns. It was shown that increase of the liquid flow rate causes an increase of both the effective liquid and gas velocity through the fluidized bed, which may also improve mass transfer.

New Food Drying Technologies - Use of Ultrasound

2003 ◽  
Vol 9 (3) ◽  
pp. 215-221 ◽  
Author(s):  
A. Mulet ◽  
J. A. Cárcel ◽  
N. Sanjuán ◽  
J. Bon
Keyword(s):  
Mass Transfer ◽  
Water Availability ◽  
Water Transfer ◽  
Threshold Power ◽  
External Resistance ◽  
Solid Foods ◽  
Mechanical Waves ◽  
Liquid Systems ◽  
Salt Brine ◽  
Solid Liquid

Reducing water availability is one way to preserve food. Water in solid foods is transferred to a fluid, either gas or liquid; during this process both internal and external resistance affect water transfer from the food. As a consequence, any means to reduce those resistances constitute an improvement of the process, and ultrasound appears to be a way to reduce those resistances. Ultrasound are mechanical waves that produce different effects when travelling through a medium. Among others, those related to mass transfer include micro-stirring at the interface, the so called “sponge effect” and cavitations. Ultrasound has so far been applied to dehydration in solid-gas systems like onion drying. Nevertheless, the difficulties for the propagation in the air have led to the development of specially adapted transducers that have been applied in the drying of carrots. In solid-liquid systems, ultrasound has been used in the treatment of products immersed in hypertonic solutions, either in sugar solutions for fruits like apples or in salt brine in the case of cheese or meat. An increase in mass transfer is achieved if the threshold power value for the product is attained.

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