Mass Transfer Coefficients For CO Research Articles

Predictions of equilibrium solubility and mass transfer coefficient for CO2 absorption into aqueous solutions of 4-diethylamino-2-butanol using artificial neural networks

In the present work, artificial neuron network (ANN) based models for predicting equilibrium solubility and mass transfer coefficient of CO 2 absorption into aqueous solutions of high performance alternative 4-diethylamino-2-butanol (DEAB) solvent were successfully developed. The ANN models show an outstanding predictive performance over the predictive correlations proposed in the literature. In order to predict the equilibrium solubility, the ANN model were developed based on three input parameters of operating temperature, concentration of DEAB and partial pressure of CO 2 . An outstanding prediction performance of 2.4% average absolute deviation (AAD) can be obtained (comparing with 7.1–8.3% AAD from the literature). Additionally, a significant improvement on predicting mass transfer coefficient can also be achieved through the developed ANN model with 3.1% AAD (comparing with 14.5% AAD from the existing semi-empirical model). The mass transfer coefficient is considered to be a function of liquid flow rate, liquid inlet temperature, concentration of DEAB, inlet CO 2 loading, outlet CO 2 loading, concentration of CO 2 along the height of the column.

Mass Transfer Coefficients for CO2 Absorption into Aqueous Ammonia Using Structured Packing

In this study, the gas phase volumetric overall mass transfer coefficients (KGae) for CO2 absorption into aqueous ammonia solutions were measured to explore the mass transfer performance of a colum...

Study of a Novel Solvent System for CO2 Capture from Post-Combustion Flue Gas

Abstract CAER-S2 solvent system developed in the Center for Applied Energy Center at the University of Kentucky has the advantages of fast CO 2 removal rate, high thermal stability, low volatility, and commercial quantity available. Vapor liquid equilibrium measurement shows that the solvent has a lower partial pressure than that of MEA at scrubber temperatures. Such feature makes the solvent a promising candidate for carbon capture from natural gas-fired flue gas which has low CO 2 concentration. Mass transfer coefficients of CO 2 in the solvent system are tested using a wetted-wall column with simulated gases at the scrubber condition. Experimental results indicate that the mass transfer coefficient increases with the increasing of temperature over the studied range, which is different from the studies on MEA. Such results suggest that the solvent is preferable to be operated at elevated temperature in scrubber at which physical mass transfer limitation is minimized without sacrificing too much driving force.

Evaluation of hydrogen and carbon monoxide mass transfer and a correlation between the myoglobin-protein bioassay and gas chromatography method for carbon monoxide determination

Myoglobin-protein bioassay, which is a much simpler, faster and cheaper method compared well with GC analysis, can be used as a reliable method of determining the volumetric mass transfer coefficient of CO in syngas fermentation studies.

Mass transfer studies on split-packing and single-block packing rotating packed beds

In this work, SO2 absorption in aqueous NaOH (gas side mass transfer resistance controlled system) and O2 desorption from the water (liquid side mass transfer resistance controlled system) are experimentally evaluated for enhancement in the controlling side volumetric mass transfer coefficient using the novel split-packing and conventional single-block rotating packed bed (RPB) designs. In the split-packing RPB design, mass transfer characteristics for co-rotation and counter-rotation of adjacent rings are studied. For the SO2 absorption system, results show a significant reduction in the controlling mass transfer resistance for split-packing over single-block packing for large RPBs. However, the mass transfer coefficients for co- and counter-rotation are comparable. For the O2 desorption system, at low rotation rates, the split-packing design gives higher mass transfer rates compared to the single-block packing. This difference disappears as the rotation rate is increased. Possible reasons for the experimental observations are speculated. The results suggest the split packing design to be more suitable for gas side mass transfer resistance controlled systems.

Determination of Mass-Transfer Coefficient of CO2in NH3and CO2Absorption by Materials Balance in a Rotating Packed Bed

More-accurate overall mass-transfer coefficients in a rotating packed bed (RPB) and local mass-transfer coefficients in different regions of the RPB were deduced by the material balance in order to obtain practical volumetric mass-transfer coefficients in the RPB. Experimental studies on the overall volumetric mass-transfer coefficients (KGa) of CO2 in NH3 and CO2 absorption into water in the RPB was carried out under different conditions. The experimental results indicated that there was a great difference between the value of KGa and KGa* attained by different boundary conditions. And it was concluded that an accurate design equation should be adopted to achieve a practical value of KGa in the RPB. It was also found that the KGa of CO2 increased with the increase of rotation speed, liquid volumetric flow rate, gas volumetric flow rate, NH3/CO2 molar ratio, and the decrease of temperature. The KGa of CO2 in the simultaneous absorption process of NH3 and CO2 was 2–6 times higher than that in the single CO2 absorption process.

Mass Transfer Coefficients for CO2 Absorption into Aqueous Ammonia Solution Using a Packed Column

The absorption of carbon dioxide into aqueous ammonia solution using a packed column was investigated. The volumetric overall mass transfer coefficients (KGaV) for CO2 absorption into aqueous ammonia solutions were evaluated over ranges of main operating variables, that is, up to 15 kPa partial pressure of CO2, 61–214 m3/(m2·h) gas flow rate, 0.76–3.06 m3/(m2·h) liquid flow rate, 2%∼16% ammonia mass fraction, and 20–50 °C temperature. An empirical KGaV correlation for this system was proposed. Experimental results show that the mass transfer process in CO2 absorption into aqueous ammonia solution is mainly controlled by the resistance in the liquid phase and the ammonia concentration has a great effect on the overall mass transfer coefficient.

Results from trialling aqueous NH 3 based post-combustion capture in a pilot plant at Munmorah power station: Absorption

Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO) and Delta Electricity have developed, commissioned and operated an A$7 million aqueous NH 3 based post-combustion capture (PCC) pilot plant at the Munmorah black coal fired power station in Australia. The results from the pilot plant trials will be used to address the gap in know-how on application of aqueous NH 3 for post-combustion capture of CO 2 and other pollutants in the flue gas and explore the potential of the NH 3 process for application in the Australia power sector. This paper is one of a series of publications to report and discuss the experimental results obtained from the pilot plant trials and primarily focuses on the absorption section. The pilot plant trials have confirmed the technical feasibility of the NH 3 based capture process. CO 2 removal efficiency of more than 85% can be achieved even with low NH 3 content of up to 6 wt%. The NH 3 process is effective for SO 2 but not for NO in the flue gas. More than 95% of SO 2 in the flue gas is removed in the pre-treatment column using NH 3. The mass transfer coefficients for CO 2 in the absorber as functions of CO 2 loading and NH 3 concentration have been obtained based on pilot plant data.

Determination of gas bubble fractionation rates in the deep ocean by laser Raman spectroscopy

A new deep-sea laser Raman spectrometer (DORISS—Deep Ocean Raman In Situ Spectrometer) is used to observe the preferential dissolution of CO 2 into seawater from a 50%–50% CO 2–N 2 gas mixture in a set of experiments that test a proposed method of CO 2 sequestration in the deep ocean. In a first set of experiments performed at 300 m depth, an open-bottomed 1000 cm 3 cube was used to contain the gas mixture; and in a second set of experiments a 2.5 cm 3 funnel was used to hold a bubble of the gas mixture in front of the sampling optic. By observing the changing ratios of the CO 2 and N 2 Raman bands we were able to determine the gas flux and the mass transfer coefficient at 300 m depth and compare them to theoretical calculations for air–sea gas exchange. Although each experiment had a different configuration, comparable results were obtained. As expected, the ratio of CO 2 to N 2 drops off at an exponential rate as CO 2 is preferentially dissolved in seawater. In fitting the data with theoretical gas flux calculations, the boundary layer thickness was determined to be ∼ 42 μm for the gas cube, and ∼ 165 μm for the gas funnel reflecting different boundary layer turbulence. The mass transfer coefficients for CO 2 are k L = 2.82 × 10 − 5 m/s for the gas cube experiment, and k L = 7.98 × 10 − 6 m/s for the gas funnel experiment.

314 マイクロチャネルを用いたCO_2物質移動係数測定に関する予備実験(OS3-2 混相流の可視化,OS3 流れ可視化と知的流体情報学の展開)

314 マイクロチャネルを用いたCO_2物質移動係数測定に関する予備実験(OS3-2 混相流の可視化,OS3 流れ可視化と知的流体情報学の展開)

Effect of Taylor vortices on calcium carbonate crystallization by gas–liquid reaction

The effects of Taylor vortices on the mean size, size distribution, and morphology of calcium carbonate crystallized by the reaction of gaseous carbon dioxide and aqueous calcium hydroxide were experimentally investigated in a Couette–Taylor reactor. Via the absorption of CO 2 gas into pure water, the mass transfer coefficient of CO 2 at the gas–liquid interface was measured relative to the rotating speed of the inner cylinders in the Couette–Taylor reactor. Polymorphs of rhombohedral-, spindle-, and needle-shaped calcium carbonate crystals were observed with a change in the operating variables, including the reactant concentration and flow rate and the rotating speed of the inner cylinder in the Couette–Taylor reactor. Using a dimensionless parameter consisting of the operating variables, it was demonstrated that the morphological changes in the calcium carbonate crystals in the present reactor could be anticipated from the operating conditions. In the crystallization, the mean crystal size, predominantly controlled by crystal agglomeration, was most influenced by the fluid dynamic conditions related to the rotating speed of the inner cylinder and reactor geometry.

Behavioral study on hydrogen fermentation reactor installed with silicone rubber membrane

This investigation examines the effectiveness of a silicone rubber membrane to separate biogas from the liquid medium in the hydrogen fermentation reactor. When the culture liquid circulates through the shell side of the hollow fibers, the biogas diffuses into the lumen of the hollow fibers and is removed by a vacuum pump. When the cross flow velocity along the module increases from 0.33 to 1.19 cm/s , the CO 2 mass transfer coefficient increases by a factor of 3.9, from 0.81×10 −7 to 3.19×10 −7 cm/s kPa , and the H 2mass transfer coefficient increases by a factor of 3.5, from 0.55×10 −8 to 1.96×10 −8 cm/s kPa . The mass transfer coefficients of CO 2 and H 2 are directly proportional to the cross flow velocity, and the values for CO 2 exceed those for H 2. However, silicone rubber effectively reduces the biogas partial pressure in the hydrogen fermentation reactor, and improves the hydrogen evolution rate by 10% and the hydrogen yield by 15%.

Mass transfer and structure of bubbly flows in a system of CO 2 disposal into the ocean by a gas-lift column

A new method for ocean sequestration of low-purity CO 2 gas emitted from fired power plant is developed. This is a gas-lift pump system, named progressive gas lift advanced dissolution (P-GLAD) system, to dissolve only CO 2 gas of combustion gas in seawater at shallow waters and to transport CO 2-rich seawater to great depths. The system is an inverse-J pipeline set at the ocean at a depth between 200 and 3000 m and a releasing system of indissoluble gas. To improve the efficiency of the P-GLAD, one should elucidate bubbly flows accompanying gas phase dissolution formed in the gas-lift column of the system. In the present paper, first, the authors discuss mass transfer in bubbly flows of pure CO 2 gas and filtrated tap water along the pipe axis in laboratory-scale P-GLAD of 25 mm in diameter and 7.69 m in height. Second, mass transfer in bubbly flows of mixed gas (95% volume of CO 2 and 5% volume of pure air) and filtrated tap water in the same setup is discussed. The mass transfer coefficient of CO 2 in the later system has the values of 3.1×10 −4–8.5×10 −5. It is shown that the mass transfer coefficient is a function of the distance from the gas injection. Finally, the performance of the system is elucidated on the basis of the experimental and numerical investigations. The laboratory-scale P-GLAD dissolved over 98.5% of CO 2 injected in the liquid phase.

High-efficiency structured packing for CO2 separation using 2-amino-2-methyl-1-propanol (AMP)

Abstract The feasibility of using high-efficiency structured packing in CO 2 separation processes with a newly proposed solvent, 2-amino-2-methyl-1-propanol (AMP), was investigated. The packing performance was evaluated in terms of overal mass transfer coefficients of CO 2 absorption into aqueous sodium hydroxide and AMP solutions over ranges of main operating variables, i.e. up to 10 kPa partial pressure of CO 2 , 0.29–0.61 m 3 m −2 s −1 gas rate, 4.87–14.18 m 3 m −2 h −1 liquid rate, and 1.1–2.0 kmol m −3 liquid concentration. The experimental results showed that the structured packing provides 10 to 33 times higher overall mass transfer coefficients than commenly used random packings.

Effect of water on the solubility and mass transfer coefficients of CO and H 2 in a Fischer-Tropsch liquid

The effects of water on the solubilities (C*) and mass transfer coefficients (k La) for CO and H 2, in a medium fraction (C 11 – C 22 of Fischer-Tropsch (FT) liquid were examined at elevated temperatures (423 – 498 K) and pressures (1 – 4 MPa, and at different stirring speeds. A new procedure, which utilizes only pressure-temperature data for FT liquid-water mixtures to estimate the equilibrium solubility of water in FT fraction is presented. The equilibrium solubility values of water in FT liquid increased with temperature and were higher than those reported in the literature for higher paraffins. The solubilities of CO and H 2 in FT liquid saturated with water increased with both pressure and temperature, and Henry's law behavior was adequate to express the experimental values. The C* values for H 2 appeared to be more sensitive to the presence of water than those for CO. k La values for H 2 at 700, 1000 and 1200 rpm decreased with the presence of water in FT liquid. For CO, however, k La values obtained at 1000 and 1200 rpm were higher in FT liquid saturated with water than those obtained in FT liquid containing no water. k La values for both CO and H 2 increased considerably with the specific power input and slightly with pressure and temperature.

Solubility and mass transfer of CO and H 2 in Fischer—Tropsch liquids and slurries

Solubilities C* and mass transfer coefficients k L a of CO and H 2 in three Fischer—Tropsch liquid fractions were measured as functions of temperature (373 – 523 K), pressure (1 – 4 MPa) and stirrer speed (800 – 1100 rev min −1) in a mechanically agitated and surface-aerated vessel. Measurements were carried out using a transient absorption techique. The solubilities of both CO and H 2 increase with temperature and pressure in the ranges examined; the solubilities of CO are 50% – 75% higher than those for H 2. It was found that C* can be expressed by Henry's law and for otherwise identical conditions it decreases with increasing carbon number of the liquid. In general, the mass transfer coefficients for CO and H 2 are of the same order of magnitude. The results indicate a dependence of k L a on temperature, pressure, stirrer speed and molecular weight of the liquid. The presence of solids decreases k L a significantly, but mix ing power strongly enhances k L a.