Volumetric Liquid-side Mass Transfer Coefficient Research Articles

Effect of packed bed on mass transfer in external-loop airlift bubble column.

The influence of packed bed set in the riser section on the liquid-side volumetric mass transfer coefficient (KLaR) in an external-loop airlift bubble column was examined with water, 20 wt% glycerol, 10 wt% ethanol and 0.3 wt% CMC aqueous solutions. The KLaR was determined by the measurement of time-dependent oxygen concentration dissolved in the liquids. Bubble size, bubble rise velocity and gas holdup in the riser were measured to examine the effect of the packed bed using an optical fiber two-phase flow system. The presence of the packed bed in the riser increased the KLaR values for the liquids used. This was associated with the increase in the specific gas-liquid interfacial area due to bubble breakage by the packed bed. In addition, a correlation equation for KLaR was proposed for both types of airlift bubble columns with and without the packed bed.

Mass transfer characteristics of fixed beds with cocurrent upflow and downflow. A special refence to the effect of pressure.

Interfacial areas and liquid-side mass transfer coefficients are determined in a trickle-bed reactor (TBR) and in a flooded-bed reactor (FBR) by means of two chemical absorption systems. The effect of gas and liquid mass flow rates and liquid viscosity is studied for both reactors as well as the influence of pressure (gas density) for TBR. In both TBR and FBR, interfacial area increases with liquid viscosity and fluid mass flow rates. It is also shown that in TBR, at given mass flow rates, interfacial areas and volumetric liquid-side mass transfer coefficients increase with gas density. In the case of FBR, the volumetric liquid-side mass transfer coefficient decreases slightly with the liquid viscosity. A new correlation is proposed for the interfacial area in FBR.

Solubilities and mass transfer coefficients of carbon monoxide in a gas-inducing reactor operating with organic liquids under high pressures and temperatures

Equilibrium gas solubility( C*) and volumetric liquid-side mass transfer coefficients( k L a) were measured for carbon monoxide in n-hexane, n-decane and n-tetradecane under various operating conditions in a four-liter gas-inducing agitated autoclave. In the range of operating conditions investigated, C* (in n- hexane) > C* (in n-decane) > C* (in n-tetradecane). The K L a values for CO in all liquids used increased with mixing speed and pressure, but decreased with increasing liquid volume. The data also showed that k L a (in n-tetradecane) > k L a (in n-decane) > k L a (in n-hexane). An empirical correlation to predict k L a values was proposed.

Mass transfer of oxygen and methane in silicone fluids and perfluoroalkyl polyether

Volumetric liquid-side mass-transfer coefficients of O 2 and CH 4 in silicone fluids and a perfluoroalkyl polyester were measured at elevated temperatures (373-573 K) and pressures (10-65 bar). A transient absorption technique was utilized to measure k L a in an agitated vessel. The volumetric liquid-side mass-transfer coefficients (k L a) for O 2 and CH 4 increased with temperature, pressure, and stirring speed in the range examined ; the volumetric liquid-side mass-transfer coefficients of O 2 were 10-50% higher than those for CH 4 . The effect of temperature on k L a has been examined for Newtonian fluids (200F 100CS silicone fluid and krytox 143AD oil) and a dilatant fluid (550F silicone fluid)

Mass transfer coefficients in a trickle-bed reactor with high and low viscosity organic solutions

Some experimental data are presented for the volumetric liquid-side mass transfer coefficients, coupled with the total liquid hold-up and two-phase pressure drop, for the weak interaction regime in a catalytic-packed-bed reactor. The measured k L a, ΔP/Z and β values for viscous solutions were about four times those observed for low-viscosity organic solutions. An empirical correlation for predicting k L a values in trickling flow regime is proposed. T001 Some available literature data and correlations for the k L a Author Study Packing Correlation d p × 10 3 (M) Nature Reiss [12] Absorption of O 2 into water from air at 25 °C 7.62 to 40.64 R.R. {fx1-41} Hirose et al. [15] Desorption of O 2 into N 2 from the water at 15°C 2.59 12.2 G.B. {fx2-41} Gianetto et al. [13] Desorption of O 2 in air from (2 N) NaOH solution 6 B.S R.R. G.B. {fx3-41} Ufford and Perona [14] Absorption of CO 2 in water 19 6.3 12.7 B.S. R.R. R.R. {fx4-41} Sylvester and Pitayagulsarn [16] Absorption of pure CO 2 in water 3.18 3.18 C Goto and Smith [17] Desorption of O 2 in pure N 2 from distilled water saturated with pure O 2. 0.541 2.91 CuZnO C.P. k L a D A = α ( L μL ) n (Sc) 0.5 Sc = μ L/ϱ L D A α and n are constants Turek and Lange [22] Hydrogenation of α-methylstyrene to cumen (organic solution) 0.54 0.90 3.00 Pa/Al 2O 3 C.P. N.A. R.R. = Raschig rings; G.B. = glass beads; B.S. = Berl saddles; C = cylinders; C.P. = catalytic particles. N.A. = Not available.

Influence of liquid properties on mass transfer coefficients in bubble columns

The gas phase holdup, the specific interfacial area a, and the liquid-side volumetric mass transfer coefficient kLa have been determined for two selected binary systems water-butanol and butanol-2-ethylhexanol in a short bubble column of 150 mm i.d. at gas phase velocities (air) in the range of uG = (0.31-2.52) . 10-2 m s-1. The kLa-uG dependences show characteristic maxima which only partially can be explained by molecular and surface force interactions, induced by the liquid phase. The main parameter, influencing the kLa-values, is a. At small gas velocities some irregularities in the Sauter diameter d32 and in the values of separated kL are observed.

Determination of liquid-side and gas-side volumetric mass transfer coefficients in a bubble column.

Experiments were carried out on bubble stripping of aqueous solutions of five organic solutes and oxygen dissolved at initial concentrations ranging from 0.008 to 0.04kg⋅m-3. Little interaction was found to exist among the solutes, as far as gas holdup and overall volumetric mass transfer coefficients at low concentrations are concerned. The liquid-side and gas-side volumetric mass transfer coefficients were obtained from measured overall coefficients. Correlations for the liquid-side volumetric mass transfer coefficients were obtained in terms of liquid-phase diffusivity and gas flow rate for two types of gas spargers: single-nozzle and porous-tube spargers. Correlations for the gas-side volumetric mass transfer coefficients were also obtained for these spargers.

Gas-liquid mass transfer characteristics in a bubble column with suspended sparingly soluble fine particles

(To investigate the influence of suspended particles on mass transfer characteristics in a slurry bubble column, physical and chemical absorptions were performed into aqueous slurries of fine calcium hydroxide particles ca. 7 ..mu..m in average size. Such mass transfer parameters as volumetric liquid-side mass transfer coefficient, specific gas-liquid interfacial area, and hence liquid-side mass transfer coefficient were determined under various electrolyte concentrations, solid concentrations, and gas flow rates.) and K /SUB L/ /SUP o/ a could be correlated by the gas flow rate. (The volumetric gas-side mass transfer coefficient was determined and correlated by the gas flow rate. The enhancement factors during absorption of dilute carbon dioxide into aqueous calcium hydroxide slurries were compared with the theoretical predictions based on the film theoryincorporating a finite slurry concept.)

Gas holdup and kLa in perforated-plate bubble columns in the presence of solid particles

The effect of solid particles on values of volumetric liquid-side mass transfer coefficient, kLa, and gas holdup, εG, was determined in a bubble column 0.14 m in diameter within the range of solid phase concentration cS = 0-10% (mass). Experiments were carried out in air-water system at zero liquid flow rate, glass spheres of average diameters 24, 36, 50, 102, 142, 190, and 280 μm and fine Zn0 powder (average particle size 2.3 μm) were used as a solid phase. Perforated plate with holes diameter 1.6 mm and free plate area 0.2% was used for gas distribution, superficial gas velocities ranged between 0.036 and 0.215 m/s. Only negative effect of the gas holdup and kLa was observed in the whole range of experimental conditions, this effect being most pronounced in the region of small particle sizes (dS ⪬ 36 μm).

Gas-liquid mass transfer in the jet reactor with liquid jet ejector.

Liquid-side volumetric mass transfer coefficients and effective gas-liquid specific interfacial areas were measured from the longitudinal distribution of oxygen concentration in gas phase by catalytic sulfite oxidation with air in the spouting and the calm sections, which were the lower and upper regions respectively in the jet reactor with liquid jet ejector. Both liquid-side volumetric coefficients and effective gas-liquid specific interfacial areas increased with the kinetic energy of the liquid jet, and their values in the spouting section were larger than those in the calm section. Further, effective gas-liquid specific interfacial area showed greater values than in other types of reactors, at a similar power supply per unit reactor volume.

Hydrodynamics and mass transfer in uniformly aerated bubble column reactors

Condirions of stable, uniform gas distribution were studied in bubble-type reactors with sieve plates and the effect of geometric parameters of distributing plates and physical properties of liquid phase on the character of the uniformly bubbled bed and on its porosity was considered. Critical velocity in the holes of the plate corresponding to the onset of stable performance of distributing plates has been found to be a function of hole diameter and physical properties of phases. A simple semiempirical relation for the estimate of ranges of stability of sieve plates has been verified on basis of experimental data. Under the conditions of stable uniform gas distribution two differing bubbling regimes were observed in all studied gas-liquid systems. In the region of homogeneous bubbling regime the gas holdup has been at comparable conditions in all cases significantly greater than in the turbulent regime. Experimental data of volumetric liquid-side mass transfer coefficient kLa have demonstrated suitability of the homogeneous bubbling regime for obtaining an intensive interphase contact in the bubbled bed.

Mass transfer in bubble columns packed with motionless mixers

The cocurrent upward mode was employed to absorb pure oxygen into water in bubble columns packed with Koch (Sulzer) motionless mixers. The liquid-side volumetric mass transfer coefficient, K La , in the packed bubble column was found to be always larger than that in the unpacked bubble column. In the range of liquid velocities from 6.7 cm/sec to 39.9 cm/sec, the value of K La in the packed bubble column increased with the increasing liquid velocity while that in the unpacked bubble column was almost independent of the liquid velocity. The equation of the form K La = mν l βϵ was successfully adopted to correlate the K La data.

Liquid-side volumetric mass transfer coefficient in upward two-phase flow of air-liquid mixtures.

Liquid-side volumetric mass transfer coefficients were obtained in vertical upward two-phase flow by desorbing carbon dioxide from liquid phases of water, aqueous glycerine and malt honey. Measurements were made mainly in the froth and the wavy annular flow using tubes of 10, 18 and 25 mm i.d. A correlation for the volumetric mass transfer coefficient was developed semi-empirically based on the analogy between mass and momentum transfer. Experimental data were correlated by two equations in dimensionless form corresponding to the two flow mechanisms of pseudo-laminar flow and turbulent flow.