Modified modeling of the effect of pH and viscosity on the mass transfer in hydrophobic hollow fiber membrane contactors

2005 ◽  
Vol 250 (1-2) ◽  
pp. 269-276 ◽  
Author(s):  
Z ZHU ◽  
Z HAO ◽  
Z SHEN ◽  
J CHEN
Keyword(s):  
Mass Transfer ◽  
Hollow Fiber ◽  
Hollow Fiber Membrane ◽  
Fiber Membrane ◽  
Effect Of Ph ◽  
Membrane Contactors

Mass transfer simulation of solvent extraction in hollow-fiber membrane contactors

Desalination ◽  
2011 ◽  
Vol 275 (1-3) ◽  
pp. 126-132 ◽  
Author(s):  
Farzad Fadaei ◽  
Saeed Shirazian ◽  
Seyed Nezameddin Ashrafizadeh
Keyword(s):  
Mass Transfer ◽  
Solvent Extraction ◽  
Hollow Fiber ◽  
Hollow Fiber Membrane ◽  
Fiber Membrane ◽  
Membrane Contactors

scholarly journals Ozone mass transfer behaviors on physical and chemical absorption for hollow fiber membrane contactors

2017 ◽  
Vol 76 (6) ◽  
pp. 1360-1369 ◽  
Author(s):  
Yong Zhang ◽  
Kuiling Li ◽  
Jun Wang ◽  
Deyin Hou ◽  
Huijuan Liu
Keyword(s):  
Mass Transfer ◽  
Hollow Fiber ◽  
Transfer Rate ◽  
Reaction Rate ◽  
Hollow Fiber Membrane ◽  
Mass Transfer Rate ◽  
Fiber Membrane ◽  
Chemical Absorption ◽  
Physical Absorption ◽  
Membrane Contactors

To understand the mass transfer behaviors in hollow fiber membrane contactors, ozone fluxes affected by various conditions and membranes were investigated. For physical absorption, mass transfer rate increased with liquid velocity and the ozone concentration in the gas. Gas flow rate was little affected when the velocity was larger than the critical value, which was 6.1 × 10−3m/s in this study. For chemical absorption, the flux was determined by the reaction rate between ozone and the absorbent. Therefore, concentration, species, and pH affected the mass transfer process markedly. For different absorbents, the order of mass transfer rate was the same as the reaction rate constant, which was phenol, sodium nitrite, hydrogen peroxide, and oxalate. Five hydrophobic membranes with various properties were employed and the mass transfer behavior can be described by the Graetz–Lévèque equation for the physical absorption process. The results showed the process was controlled by liquid film and the gas phase conditions, and membrane properties did not affect the ozone flux. For the chemical absorption, gas film, membrane and liquid film affected the mass transfer together, and none of them were negligible.

scholarly journals Mass Transfer and Fluid Hydrodynamics in Sealed End Hydrophobic Hollow Fiber Membrane Gas-liquid Contactors

2017 ◽  
Vol 2 (1) ◽  
Author(s):  
S. Kartohardjono ◽  
V. Chen
Keyword(s):  
Mass Transfer ◽  
Hollow Fiber ◽  
Packing Density ◽  
Hollow Fiber Membrane ◽  
Gas Absorption ◽  
Outer Diameter ◽  
Fiber Membrane ◽  
Membrane Area ◽  
Wide Range ◽  
Membrane Contactors

Hollow fiber membrane modules have been extensively used as gas-liquid contactor devices to provide a high surface area within a small volume. Hollow fiber membrane contactors have been demonstrated in a wide range of application such as in gas stripping and gas absorption. In this study the performance of sealed end hydrophobic microporous hollow fiber membranes contactors were evaluated to remove dissolved oxygen from water via vacuum degassing process. Hollow fibers membranes used in the experiment were hydrophobic microporous polypropylene of 650 μm in outer diameter, 130 μm wall thickness and nominal pore size of 0.2 μm. Based on the experimentalresult the sealed end membrane contactor can remove oxygen from water as high as 3.4-gram oxygen per square meter of membrane area per hour. The oxygen flux decreases with increasing module-packing density for the same water velocity. The same effect also occurred for the mass transfer coefficient of the membrane contactors. The mass transfer coefficients were independent of fiber length within the range of study. Hydrodynamics analysis of the contactors showed that at the same Reynolds number pressure drops increase with increasing packing density due to an increase in friction between fibers and water.

Mathematical Simulation of Membrane-Absorption for H2S Capture from Nature Gas

2013 ◽  
Vol 302 ◽  
pp. 20-25
Author(s):  
Lu Ma ◽  
Shu Li Wang ◽  
Jian Wang ◽  
En Tian Li ◽  
Xin Cao
Keyword(s):  
Mass Transfer ◽  
Hydrogen Sulfide ◽  
Hollow Fiber ◽  
Hollow Fiber Membrane ◽  
Sulfur Removal ◽  
Operating Conditions ◽  
Operating Costs ◽  
Fiber Membrane ◽  
Nature Gas ◽  
Membrane Contactors

A dynamic model of mass transfer was developed with mass transfer equation and mass transfer differential equation according to two film theory for the simultaneous transport of hydrogen sulfide through hollow fiber membrane (HFM) contactors while using N-methyldiethanolamine (MDEA) as the chemical solvent. The model results are in excellent agreement with the experimental data. The results indicate that the removal of H2S increased while increasing concentration of MDEA and gas pressure, however, the removal of H2S decreases while increasing gas velocity. The concentration of H2S increases at the same place in the lumen while increasing gas velocity. There is serious decreasing amplitude of axial concentration of H2S during the initial stage, but it slows down at half of the length and a great reduction of H2S concentration in radial direction with the increase of the length. The decreasing amplitude is dropped due to the concentration of H2S decreased in radial direction. The model can indicate H2S removal rate in given operational conditions and offer theory evidence for the design of membrane contactor. Natural gas is believed to play a vital role in the next few decades for industrial and domestic utilization. It is considered as one of the cleanest and safest of all energy sources. However, nature gas is not a pure hydrocarbon and sometimes it has some sour gases such as hydrogen sulfide which has high toxicity. Hydrogen sulfide can not only corrode equipment and transmission pipeline under aerobic and hot humid conditions but also cause catalyst poisoning, even serious threaten the safety of human. Wet desulphurization is widely used for natural gas treatment and aqueous solutions of alkanolamines are often used as absorption solvent. Among these alkanolamines, MDEA as an absorption solvent of acid gases is widely used today because it possesses the characteristics such as higher H2S selectivity, bigger absorption capacity, lower regeneration energy, smaller hot-degradation and lower circulating load. But desulphurization unit can be seriously corroded in the sulfur removal process. On the other hand, these conventional processes such as absorption towers, packed and plate columns possess many disadvantages such as flooding, foam formation, and demand high capital and operating costs. So the technology meets a certain obstacles. Recently, new processes using gas–liquid membrane contactors as gas absorption devices have been a subject of great interest. Among the diversity of membrane geometries available for membrane contactors, hollow-fiber membrane contactors are favored due to their high surface/volume ratio for separation which is 30-50 times compared with traditional absorbers. This type of process offers several practical advantages including low energy and operating costs, simplicity and occupying small area. In addition, membrane contactors as unit equipment can be combined according to actual need. [4~5] used polypropylene hollow fiber membrane as the absorber and MDEA as the chemical solvent for the absorption of H2S via changing operating conditions (e.g. temperature, pressure, the concentration of the solvent, flux of gas-liquid phase) and studied the influence of the changes to mass transfer coefficient and sulfur removal efficiency. The results indicate that the sulfur removal efficiency can be 95% above by optimizing the operating conditions. At home and abroad, comprehensive two-dimensional mathematical models were developed based on differential equation. Wang [6] simulated the absorption of CO2 using different absorption medium in hollow fiber membrane contactors. But they did not consider the effect of mixed gas. Chen [7] modeled the distribution of reactants and products concentration in the shell side in different typ es of reaction. However, the model can not obtain the concentration of H2S in the lumen. Rami Faiz [8] modeled the distribution of acid gas, but the mathematical model was not validated by the experimental work.

Simulation of external mass transfer in hollow-fiber membrane contactors

2015 ◽  
Vol 55 (10) ◽  
pp. 776-782 ◽  
Author(s):  
V. A. Kirsch ◽  
V. I. Roldugin ◽  
S. D. Bazhenov ◽  
T. V. Plisko
Keyword(s):  
Mass Transfer ◽  
Hollow Fiber ◽  
Hollow Fiber Membrane ◽  
External Mass Transfer ◽  
Fiber Membrane ◽  
Membrane Contactors

Experimental Study on Separation of CO2 by Using Hollow Fiber Membrane Contactors with Amino Acid Salts Solutions

2011 ◽  
Vol 356-360 ◽  
pp. 1362-1366
Author(s):  
Wei Feng Zhang ◽  
Zhong Hua Lin
Keyword(s):  
Mass Transfer ◽  
Hollow Fiber ◽  
Transfer Rate ◽  
Hollow Fiber Membrane ◽  
Mass Transfer Rate ◽  
Operating Conditions ◽  
Fiber Membrane ◽  
Amino Acid Salts ◽  
Membrane Contactors ◽  
Lower Liquid

Experimental on CO2 removal from flue gas using polypropylene hollow fiber membrane contactors were conducted in this study. Absorbents including aqueous PG, SG were used to absorb CO2 in the experiments, and comparing with aqueous MEA. The experimental results showed that the mass transfer rate of PG and SG increased gradually in experiments while the absorbent concentration can not be elevated without limitation. That may show the mass transfer rate will be eventually saturated at a certain concentration value. The aqueous PG can be selected to absorb CO2 in membrane contactors at a lower liquid flow rate to reduce the potential to wet the membrane. Comparing PG and SG with MEA. The performance of PG is superior to SG and MEA under the same operating conditions.

An Analytical Solution to Heat and Mass Transfer in Hollow Fiber Membrane Contactors for Liquid Desiccant Air Dehumidification

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
Li-Zhi Zhang
Keyword(s):  
Mass Transfer ◽  
Analytical Solution ◽  
Heat And Mass Transfer ◽  
Hollow Fiber ◽  
Hollow Fiber Membrane ◽  
System Optimization ◽  
Operating Conditions ◽  
Fiber Membrane ◽  
Liquid Desiccant ◽  
Membrane Contactors

Hollow fiber membrane contactors are used in air dehumidification. The benefit of this technology is that the liquid desiccant is not in a direct contact with the process air; therefore, the problem of liquid droplets crossover is prevented. The equations governing the heat and moisture transfer from the air to the liquid, through the membranes, are described. An analytical solution is obtained for the dimensionless differential equations, with which the dehumidification effectiveness could be estimated by simple algebraic calculations. It provides a convenient yet accurate tool for the component design and system optimization. The model is validated by experiments. The effects of varying operating conditions on system performance are investigated. It is found that the total number of transfer units for sensible heat and the overall Lewis number are the most dominant parameters influencing heat and mass transfer.

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