Gas separation hollow fiber

High-pressure gas separation, hollow-fiber membrane modules for, 15 823 High pressure liquid chromatography (hplc), 9 234 21 275 in herbicide analysis, 13 312 polymer analysis using, 19 566 High-pressure methanol, production process, 16 300-301 High pressure methods, specialized, 13 430-431... 

Gas separation Hollow fibers for high volume applications with low flux, low selectivity membranes in which concentration polarization is easily controlled (nitrogen from air)... 

With respect to gas separation hollow fiber modules, the chemical compatibility and the mechanical stability of the fibers and potting are paramount. High pressure modules use shell-side feed while low pressure modules... 

Kapantaidakis GC, Koops GH, Wessling M. Preparation and characterization of gas separation hollow fiber membranes based on polyethersulfone-polyimide miscible blends. Desalination 2002 145(l-3) 353-7. 

Reverse osmosis spiral wound Reverse osmosis hollow fiber Gas separation hollow fiber... 

Ismail AF, Shilton SJ, Dunkin IR, Gallivan SL (1997) Direct measurement of theologically induced molecular orientation in gas separation hollow fiber membranes and effects on selectivity. J Membr Sci 126(1) 133-137... 

Reverse osmosis hoUow fiber Gas separation hollow fiber Hemodialysis hollow fiber Turbulent (shell-side fed) Laminar Laminar (entry region) Shell-side fluid Membrane Core-side fluid k 10 to 10 m/s Permeabilities Sh = 1.86 ReSc- PDF ODF ODF... 

D. Coker, Nonisothermal model for gas separation hollow-fiber membranes, AIChE J., 1999, 45, 1451-1468. 

Operation of Gas Separation Hollow Fiber Membrane Modules... 

Nardella A., Demofonti C., Santarossa R., Sisto R. and Valentini C., Spinning of Modified Poly (2, 6-dimethyl-p-oxyphenylene) into Gas Separation Hollow fibers and Assembling of Prototype Separators, J. Membr. Sci., 1995,105,31-41. 

For gas separation hollow fibers, there have been a few systematic studies on the effect of spinning parameters on both the macroscopic dimensions and permeation performance. One paper studies silicone rubber coated polyimide hollow fibres (Chung et al., 1992), another silicone rubber... 

Ismail, A.F., S.J. Shilton, I.R. Dunkin and S.L. Gallivan, Direct Measurement of Rheologically Induced Molecular Orientation in Gas Separation Hollow Fiber Membranes and Effects on Selectivity , J. Membr. Sci., 126 (1997) 133-137. 

R. Rautenbach and W. Dahm, Simplified calculation of gas-permeation hollow fiber modules for the separation of binary mixtures. /. Membr. Science, 26 (1986) 319. 

Matsumiya N, Teramoto M, Kitada S, Matsuyam H. Evaluation of energy consumption for separation of CO2 in flue gas by hollow fiber facilitated transport membrane module with permeation of amine solution. Sep Purif Technol 2005 46 26-32. 

S.-P. Van, M.-X. Fang, W.-F. Zhang, S.-Y. Wang, Z.-K. Xu, Z.-Y. Luo et al., Experimental study on the separation of COj from flue gas using hollow fiber membrane contactors without wetting. Fuel Process. Tech. 88 (2007) 501-511. 

In liquid separation, hollow fiber membranes based on PBI have shown excellent performance for pervaporation dehydration of organic liquids. For example, a dual layer PEI-PBI hollow fiber membrane with an outer selective layer of PBI showed better performance than most other polymeric membranes in pervaporation dehydration of ethylene glycol. Sulfonation modifications of PBI membranes have demonstrated excellent separation efficacies in the dehydration of acetic acid. Studies have shown that PBI hollow fiber membranes were effective in separating chromates from solutions. Also, PBI nanofiltration hollow fiber membranes are promising candidates as forward osmosis membranes. In gas separation, recent studies sponsored by the Department of Energy at Los Alamos National Laboratories and SRI International demonstrated potential applications of PBI membranes in carbon capture and Hj purification from synthesis gas streams at elevated temperatures. H2/CO2 selectivity > 40 has been achieved at H2 permeability of 200 GPU at 250°C. ... 

Fig. 23. Two types of hollow-fiber modules used for gas separation, reverse osmosis, and ultrafiltration applications, (a) Shell-side feed modules are generally used for high pressure appHcations up to - 7 MPa (1000 psig). Fouling on the feed side of the membrane can be a problem with this design, and pretreatment of the feed stream to remove particulates is required, (b) Bore-side feed modules are generally used for medium pressure feed streams up to - 1 MPa (150 psig), where good flow control to minimise fouling and concentration polarization on the feed side of the membrane is desired.

A second factor determining module selection is resistance to fouling. Membrane fouling is a particularly important problem in Hquid separations such as reverse osmosis and ultrafiltration. In gas separation appHcations, fouling is more easily controlled. Hollow-fine fibers are notoriously prone to fouling and can only be used in reverse osmosis appHcations if extensive, costiy feed-solution pretreatment is used to remove ah. particulates. These fibers caimot be used in ultrafiltration appHcations at ah. 

Spiral-wound modules are much more commonly used in low pressure or vacuum gas separation appHcations, such as the production of oxygen-enriched air, or the separation of organic vapors from air. In these appHcations, the feed gas is at close to ambient pressure, and a vacuum is drawn on the permeate side of the membrane. Parasitic pressure drops on the permeate side of the membrane and the difficulty in making high performance hollow-fine fiber membranes from the mbbery polymers used to make these membranes both work against hollow-fine fiber modules for this appHcation. 

Both hollow-fiber and spiral-wound modules are used ia gas-separation appHcations. Spiral-wound modules are favored if the gas stream contains oil mist or entrained Hquids as ia vapor separation from air or natural gas separations. 

We have been studying the novel process for CO2 separation named membrane/absorption hybrid method. The advantages of this process are that high gas permeance and selectivity were obtained. The concept of this process is shown in Fig. 1. Both feed gas and absorbent solution are supplied to the inside of hollow fibers. While Ae liquid flows upward inside the hollow fibers, absorbent solution absorbs CO2 selectively and it becomes a rich solution. Most of rich solution permeates the membrane to the permeate side maintained at reduced pressure, where it liberated CO2 to become a lean solution. Compared to a conventional gas absorption... 

In the present study, we fabricated hollow fiber membrane modules and performed experiments at several conditions. The energy consumption of this process is compared to those of conventional gas absorption processes and membrane gas separation processes. 

See also Gas separation adsorption adsorbents for, 1 612 coal gasification, 6 824 commercial separations, l 618t hollow-fiber membrane modules for, 15 823... 

Low polarity plasticizers, 74 479 Low power package, 74 863 Low pressure catalytic processes, 20 151 Low pressure chemical vapor deposition (LPCVD), 5 807, 811-812 Low-pressure gas separation, spiral-wound membrane modules for, 75 823-824 Low pressure hollow-fiber membranes, 76 24-26... 

Hydrogel membranes are particularly attractive because of high permeability and separation factor [300], and good stability for CO2/N2 separation [299], PVDF hollow fiber membrane modified by alkali was coated by PYA hydrogel on its surface and PVDF-PVA hydrogel membranes show better hydrophilic performance. For carbonate hydrogel (sodium carbonate concentration of 3.7 %) membrane, C02, concentration from 1.3 % to 0.6 % in feed gas could be decreased to 0.9-0.4 % at the outlet at 25 °C. 

Koresh and Soffer (1983) developed a hollow-fiber gas separation membrane. In principle, polymeric hollow fibers can be porous (macroporosity) or dense. On thermal treatment in vacuum (pyrolysis) a second structural feature, the so-called ultramicroporosity (Koresh and Soffer 1983) was observed. This is due to small gaseous molecules channeling their way out of... 

In gas separation applications, polymeric hollow fibers (diameter X 100 fim) are used (e.g. PAN) with a dense skin. In the skin the micropores develop during pyrolyzation. This is also the case in the macroporous material but is not of great importance from gas permeability considerations. Depending on the pyrolysis temperature, the carbon membrane top layer (skin) may or may not be permeable for small molecules. Such a membrane system is activated by oxidation at temperatures of 400-450 C. The process parameters in this step determine the suitability of the asymmetric carbon membrane in a given application (Table 2.8). 

The hollow-fiber systems for gas separation or the tubular microfiltration systems have to be pyrolyzed before mounting in the membrane housing, because of the large shrinkage during pyrolysis. That is the most critical step in the fabrication of a separation system. 

In this last section some recent developments are mentioned in relation to gas separations with inorganic membranes. In porous membranes, the trend is towards smaller pores in order to obtain better selectivities. Lee and Khang (1987) made microporous, hollow silicon-based fibers. The selectivity for Hj over Nj was 5 at room temperature and low pressures, with permeability being 2.6 x 10 Barrer. Hammel et al. 1987 also produced silica-rich fibers with mean pore diameter 0.5-3.0nm (see Chapter 2). The selectivity for helium over methane was excellent (500-1000), but permeabilities were low (of the order of 1-10 Barrer). 

SSZ-13 Sheath Ultem Core Ultem and Matrimid Silane coupling Dual layer hollow fiber Gas separations (e.g.. O2/N2) [75]... 

---