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Liquid Flow Rate (liquid + flow_rate)
Selected AbstractsA pilot-scale demonstration of a membrane-based absorption- stripping process for removal and recovery of volatile organic compoundsENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2001S. Majumdar A new membrane-based continuous absorption-stripping process has been developed to separate gas/vapor mixtures, such as volatile organic compounds (VOCs), from a nitrogen/air stream. Two different hollow fiber membrane modules are needed in this process to remove the VOCs. In the first module, VOC-laden nitrogen/air stream flows through the bore of the hollow fibers. A suitable absorbent liquid with a high solubility for the VOC and essentially no solubility for nitrogen/air is pumped countercurrently over the outside of the fibers. This liquid is an inert, nontoxic, and essentially nonvolatile, organic solvent. The VOCs are effectively removed from nitrogen/air to a very low level and are concentrated in the absorbent for recovery, while the absorbent is regenerated by heating and subjecting it to vacuum in a separate hollow fiber membrane module called the stripping module. A pilot-scale membrane-based absorption-stripping unit was located next to a paint spray booth at Robins Air Force Base, Warner Robins, GA. Tests were performed on slip-streams of real-time air emissions from scheduled intermittent painting operations, so the concentration of VOC in the exhaust air fluctuated with time. The VOC removal efficiency was determined as a function of the feed air flow rate and the absorbent (silicone oil) flow rate. Depending on the gas/liquid flow rates and the inlet VOC concentration, the process successfully removed as much as 95+% of the VOC present. The experimental results have been compared with theoretical predictions. [source] Hydrodynamics and mass transfer of gas,liquid flow in a falling film microreactorAICHE JOURNAL, Issue 5 2009Haocui Zhang Abstract In this article, flow pattern of liquid film and flooding phenomena of a falling film microreactor (FFMR) were investigated using high-speed CCD camera. Three flow regimes were identified as "corner rivulet flow," "falling film flow with dry patches," and "complete falling film flow" when liquid flow rate increased gradually. Besides liquid film flow in microchannels, a flooding presented as the flow of liquid along the side wall of gas chamber in FFMR was found at high liquid flow rate. Moreover, the flooding could be initiated at lower flow rate with the reduction of the depth of the gas chamber. CO2 absorption was then investigated under the complete falling flow regime in FFMR, where the effects of liquid viscosity and surface tension on mass transfer were demonstrated. The experimental results indicate that kL is in the range of 5.83 to 13.4 × 10,5 m s,1 and an empirical correlation was proposed to predict kL in FFMR. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Dryout phenomena in a three-phase fixed-bed reactorAICHE JOURNAL, Issue 1 2003Zhen-Min Cheng Understanding the mechanism of liquid-phase evaporation in a three-phase fixed-bed reactor is of practical importance, because the reaction heat is usually 7,10 times the vaporization heat of the liquid components. Evaporation, especially the liquid dryout, can largely influence the reactor performance and even safety. To predict the vanishing condition of the liquid phase, Raoult's law was applied as a preliminary approach, with the liquid vanishing temperature defined based on a liquid flow rate of zero. While providing correct trends, Raoult's law exhibits some limitation in explaining the temperature profile in the reactor. To comprehensively understand the whole process of liquid evaporation, a set of experiments on inlet temperature, catalyst activity, liquid flow rate, gas flow rate, and operation pressure were carried out. A liquid-region length-predicting equation is suggested based on these experiments and the principle of heat balance. [source] Phase distributions in a gas,liquid,solid circulating fluidized bed riserTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2010S. A. Razzak Abstract The distributions of the three phases in gas,liquid,solid circulating fluidized beds (GLSCFB) were studied using a novel measurement technique that combines electrical resistance tomography (ERT) and optical fibre probe. The introduction of gas into a liquid,solid circulating fluidized bed (LSCFB), thus forming a GLSCFB, caused the increase of solids holdup due to the significantly decreased available buoyancy with the lower density of the gas, even with a somewhat increased liquid velocity due to the decreased liquid holdup giving space for the gas holdup. The gas passed through the riser in the form of bubbles, which tended to flow more through the central region of the riser, leading to more radial non-uniformity in radial holdup of the phases. The gas velocity has the most significant effect on the gas phase holdup. While the gas velocity also has an obvious effect to the solids holdups, the liquid flow rate had a much more considerable effect on the phase holdups. The solids circulation rate also had a significant effect on the phase holdups, with increasing solids circulation rate causing much more increased solids holdup in the central region than close to the wall. A correlation was developed for the relative radial distributions of solids holdup in GLSCFB, as such radial profiles were found similar over a wide range of operating conditions, like those in a typical gas,solid circulating fluidized beds (GSCFB). Finally, the axial solids profiles in a GLSCFB was found to be much closer to those in an LSCFB which are very uniform, than those found in a GSCFB which are less uniform and sometime having a S shape. Water was used as the continuous and conductive phase, air was the gas phase and glass bead and lava rock particles were used as the solid and non-conductive phase. Les distributions des trois phases des lits fluidisés circulants gaz-liquide-solide (LFCGLS) ont été étudiées à l'aide d'une technique de mesure originale qui combine la tomographie à résistance électrique (ERT) et la sonde à fibre optique. L'introduction de gaz dans un lit fluidisé circulant liquide-solide, formant par conséquent un lit fluidisé circulant gaz-liquide-solide, a provoqué une retenue de solides en raison de la diminution importante de la flottabilité disponible avec la densité moindre du gaz, même avec une vitesse de liquide quelque peu accrue causée par la retenue de liquide diminuée qui donne de l'espace pour la retenue de gaz. Le gaz passé dans la colonne de montée sous forme de bulles, qui avaient tendance à circuler davantage dans la région centrale de la colonne, donne une non-uniformité plus radiale dans la retenue radiale des phases. La vitesse du gaz a aussi un effet évident sur les retenues des solides; le débit du liquide a un effet beaucoup plus considérable sur les retenues des phases. Le taux de circulation des solides avait également un effet important sur les retenues des phases, le taux de circulation des solides croissant causant beaucoup plus de retenues de solides accrues dans la région centrale que près du mur. Une corrélation a été créée pour les distributions radiales relatives de la retenue des solides dans le LFCGLS, puisque de tels profils radiaux ont été trouvés semblables sur une vaste gamme de conditions d'utilisation, comme celles dans un LFCGS typique. Enfin, on a découvert que les profils des solides axiaux dans un LFCGLS sont beaucoup plus près que ceux d'un LFCLS qui sont très uniformes, que ceux découverts dans un LFCGS, qui sont moins uniformes et qui ont à peu près la forme d'un « S ». [source] Experimental studies of liquid flow maldistribution in a random packed columnTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2000Fuhe Yin Abstract Liquid flow distribution has been a major concern when scaling up random packed columns. This study concerns the measurements of liquid flow distribution in a large scale column packed with 25.4 mm stainless steel Pall rings. The liquid flow distribution was studied with packed bed height from 0.9 to 3.5 m, liquid flow rate from 2.91 to 6.66 kg/m2·s, and gas flow rate from 0 to 3.0 kg/m2·s. In addition, three systems, water/air, aqueous detergent solution/air and Isopar/air, were used to study the effect of liquid physical properties on liquid flow distribution, and two different liquid distributors were employed to test the effect of liquid distributor design. It was found that liquid flow distribution was strongly influenced by liquid distributor design, packed bed height, gas flow rate and liquid viscosity, slightly influenced by liquid flow rate, but not by liquid surface tension. La distribution de l'écoulement liquide pose un problème important pour la mise à l'échelle des colonnes garnies aléatoirement. Cette étude porte sur des mesures de distribution d'écoulement liquide dans une colonne de grande échelle garnie d'anneaux Pall en acier inoxydable de 25,4 mm de diamètre. La distribution de l'écoulement liquide a été étudiée pour une hauteur de lit garni entre 0,9 et 3,5 m, un débit liquide entre 2,91 et 6,66 kg/m2·s et un débit de gaz entre 0 et 3,0 kg/m2·s. En outre, on a eu recours à trois systèmes, soient eau/air, solution à base de détergent aqueuse/air et Isopar/air, pour étudier l'effet des propriétés physiques du liquide sur la distribution de l'écoulement liquide, et deux distributeurs de liquide différents ont été utilisés afin de tester l'effet de la conception du distributeur de liquide. On a trouvé que la distribution de l'écoulement liquide était fortement influenceé par la conception du distributeur de liquide, la hauteur de lit garni, le débit de gaz et la viscosité du liquide, était peu influencée par le débit du liquide, et n'était pas influencée par la tension de surface du liquide. [source] Two-phase bifurcated dividing pipe flowASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009A. Murphy Abstract Data are reported on the pressure drop of co-current air,water two-phase flow through 0.0454 m i.d. bifurcations with included angles of 60°, 90°, 120° and 180°. The pressure changes on account of the angles at the junctions depended on the superficial phase velocities and the angle of bifurcation. For the 60° lowest angle of bifurcation the pressure drop was insensitive to flow rates if the superficial liquid velocity was in the lower range at and below 0.1 m s,1. For higher liquid flows the pressure loss increased dramatically, particularly in the annular-type regimes. When the angle at the junction was increased, negative values of pressure loss, i.e. an increase in pressure was recorded across the bifurcation in the gas velocity region under 10 m s,1 and liquid rates at and above 0.1 m s,1 in the slug and blow-through slug regimes. The effect coincided with liquid separation from the inner inlet pipe wall of the junction and its subsequent reformation on the downstream walls. A second less dramatic increase in junction pressure drop occurred at the lowest liquid flow rate of 0.05 m s,1 for the tee (180° bifurcation) that was due both to the smooth transition of liquid through the junction and the damping of surface waves in stratified-type flow. A flow regime map was presented for the tee junction. The inlet flow showed agreement with the map but the flow regimes found in the outlet arms of the junction tended to form earlier than expected being triggered by the pressure disturbances in the passage through the bifurcation. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Effect of various parameters on the solid circulation rate in a liquid,solid circulating fluidized bedASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2008P. Natarajan Abstract A liquid,solid circulating fluidized bed (LSCFB) is operated at high liquid velocity, where particle entrainment is highly significant, and between the conventional liquid fluidized bed and the dilute-phase liquid transport regimes. In the present work, systematic experiments were carried out in a 0.094 m i.d. and 2.4 m height laboratory-scale LSCFB apparatus by using various solid particles and tap water as fluidizing medium to study the hydrodynamics. The effects of operating parameters, i.e. primary liquid flow rate in the riser (jf), auxiliary liquid flow rate (ja), total liquid flow rate (jl), particle density (,s), particle diameter (dp) and solid feed pipe diameter (do) on the solid circulation rate were analyzed from the experimental data. Finally, a correlation was developed from the experimental data to estimate solid velocity (solid circulation rate), and was compared with the present experimental and available data in the literature. They agree well with a maximum root mean-square (RMS) deviation of 12%. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source] New insight into suction and dilution effects in CE coupled to MS via an ESI interface.ELECTROPHORESIS, Issue 10 2009Dilution effect Abstract The hyphenation of CE with MS is nowadays accepted as a powerful analytical approach. As far as ESI, the most common interface, is concerned, one challenge is to provide the most sensitive as well as quantitative information, which is quite a difficult task, as it is linked, among other factors, to suction and dilution effects. In the coaxial ESI configuration, it has been previously demonstrated that suction effect depends on many parameters inherent to the ESI interface geometry, the prevailing ones being the CE capillary protrusion from the interface needle, the sheath liquid (SL) and the overall BGE flow rates and velocity profile. In this paper, dilution effect is studied, as the CE electrolyte is mixed with SL at the interface. Considering peak intensity and efficiency, this effect was studied as a function of the various parameters of the interface (capillary protrusion from the SL tube, nebulizing gas, SL and CE electrolyte flow rates) or of the source (skimmer and ESI voltages, drying gas flow rate and temperature). It appears that the dilution effect seems slightly lower than what can be anticipated from the proportions of the liquid flow rates. This study also indicates that suction effect has to be considered first to better understand the dilution phenomenon, as suction effect leads to an increase in peak intensity, before a dilution effect appears. [source] CFD modeling of flow patterns and hydraulics of commercial-scale sieve traysAICHE JOURNAL, Issue 4 2003Getye Gesit A computational fluid dynamics (CFD) model was used to predict the flow patterns and hydraulics of a commercial-scale sieve tray. The model considers the 3-D two-phase flow of gas and liquid in which each phase is treated as an interpenetrating continuum having separate transport equations. Interaction between the two phases occurs via an interphase momentum transfer. For the CFD analysis, the commercial packages CFX5.4 and CFX4.4 of AEA Technology were employed. Velocity distributions, clear liquid height, froth height, and liquid holdup fraction in froth were predicted for various combinations of gas and liquid flow rates. Tray geometry and operating conditions were based on the experimental work that Solari and Bell carried out in a 1.22-m diameter air,water simulator in 1986 at Fractionation Research Inc. Predicted results were found to be in good agreement with the experimental data of these authors. The objective of the work was studying the extent to which CFD can be used as a prediction and design tool for industrial trays. The simulation results are such that CFD can be used as an invaluable tool in tray design and analysis. [source] | ||||||||||