Fibers membrane modules

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... 

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... 

Polymer-Assisted Ultrafiltration of Boric Acid. The Quickstand (AGT, Needham, MA) filtration apparatus is pictured schematically in Figure 3. The hollow fiber membrane module contained approximately 30 fibers with 0.5 mm internal diameter and had a nominal molecular weight cut-off of 10,000 and a surface area of 0.015 m2. A pinch clamp in the retentate recycle line was used to supply back pressure to the system. In a typical run, the transmembrane pressure was maintained at 25 psig and the retentate and permeate flow rates were 25 ml/min and 3 ml/min, respectively. Permeate flux remained constant throughout the experiments. 

Figure 19.5. The Permasep hollow fiber module for reverse osmosis, (a) Cutaway of a DuPont Permasep hollow fiber membrane module for reverse osmosis a unit 1 ft dia and 7 ft active length contains 15-30 million fibers with a surface area of 50,000-80,000 sqft fibers are 25-250 pm outside dia with wall thickness of 5-50pm (DuPont Co.), (b) The countercurrent flow pattern of a Permasep module.

Daud, W.R.W. 2004. Rate-based design of non-fouled cross-flow hollow fiber membrane modules for ultratitration. Sep. Sci. Technol. 39 1221-1238. 

Hollow fine fiber membranes are extremely fine polymeric tubes 50-200 micrometers in diameter. The selective layer is on the outside surface of the fibers, facing the high-pressure gas. A hollow-fiber membrane module will normally contain tens of thousands of parallel fibers potted at both ends in epoxy tube sheets. Depending on the module design, both tube sheets can be open, or as shown in Figure 8.1, one fiber end can be blocked and one open. The high-pressure feed gas flows past the membrane surface. A portion of the feed gas permeates the membrane and enters the bore of the fiber and is removed from the open end of the tube sheet. Fiber diameters are small because the fibers must support very large pressure differences feed-to-permeate (shell-to-bore). 

Figure 8.2 The expanding diameter of Cynara hollow-fiber membrane modules, from the first 5-inch modules of the 1980s to the 30-inch diameter behemoths now being introduced (Photo used courtesy of NATCO Group, Inc.) [9],...

Kinetic analysis on reactive extraction of aspartic acid from water in hollow-fiber membrane modules. Journal of Membrane Science, 281, 186. 

Fig. 1. Experimental setup for extraction and stripping using two hollow-fiber membrane modules.

A commercial nitrogen enrichment system is illustrated in Fig. 17. Hollow-fiber membrane modules are connected to a compressed air feed at 70-150 psi. The feed in usually to the bore side of the hollow fibers. Oxygen (and water vapor that may be present) permeate out of the fiber into the shell and exit at low pressure. Dry, nitrogen-enriched air... 

On the commercial front, an artificial liver system has reached advanced clinical trial stage. Based on pig hep-atocytes immobilized in a hollow-fiber membrane module, this system provides temporary life support until a liver from a human donor is available for transplantation (Fig. 50). Also under development is an artificial pancreas intended as a permanent replacement of the native organ (Fig. 51). 

The core part of a hollow-fiber bioreactor is the hollow-fiber membrane module, also simply known as the cartridge. It consists of a plastic cylinder containing hundreds of semi-permeable capillary tubes, known as hollow fibers. The cells are inoculated in the extracapillary space (ECS). The cells colonize the external surface of the fibers and grow in this region. The culture medium is pumped through the lumen of the fibers, known as the intracapillary space (ICS), as shown in Figure 9.11. 

First commercial hollow-fiber membrane module developed by DuPont. This module configuration further increased the packing density of membrane modules. 

Figure 4.30 shows a hollow fine fiber membrane module. The fibers are folded in half and the open end of each fiber is "potted" in epoxy "tube sheet," while the folded end is potted in an epoxy, non-porous block. Feed to the module is outside in, which requires less strength on the part of the fiber than inside-out flow would. Also, the pressure drop on the outside of the fibers is much less than would be in the inside of the fiber (which is known as the lumen). 

Microfiltration and UF membranes are available in tubular, spiral wound, and hollow fiber membrane module configurations. Tubular and spiral MF and UF modules are similar to RO tubular and spiral wound membrane modules described in Chapters 4.3.2 and 4.3.3. However, while the thickest feed spacer in a spiral RO module is 34-mil, UF and MF modules nominally have up to a 45-mil spacer due to the relatively high concentration of suspended solids these membranes are called upon to treat (TriSep Corporation offers a special 65-mil spacer for dairy applications). 

Hollow fiber membrane modules can be backwashed to remove foulants whereas tubular and most spiral configurations cannot be backwashed. Backwashing of traditional spiral-wound modules would break the glue lines holding the membrane leaves together or cause blistering and delamination of the membrane from the backing in both spiral and tubular modules (TriSep Corporation has recently developed a back-washable, spiral-wound module (SpiraSep—US patent 6,755,970), that is used in immersed systems see below). 

Figure 16.8 Cross-sections of a (a) pressurized MF or UF hollow fiber membrane module and an (b) submerged hollow fiber MF membrane cartridge.

Membrane technology is also offered by other licensors an example is the Polysep Membrane System of UOP [970], In addition to the systems based on hollow fibers, membrane modules have been developed in which the membrane is in the form of a sheet wrapped around a perforated center tube using spacers to separate the layers. The raw gas flows in axial direction in the high pressure spacer and the permeate is withdrawn in the low pressure spacer. Such a module, for example, is marketed under the name Separex [971], [972],... 

Kreulen H, Smolders CA, Versteeg GF, and van Swaaij WPM, Microporous boUow fiber membrane modules as gas-bquid contactors. Part I, Physical mass transfer processes. Journal of Membrane Science 1993, 78, 197-216. 

FIGURE 4.21 Hollow fiber membrane modules with different configurations. (From Pellegrino J., Sikdar S.K., Membrane Technology, Fundamentals of Bioremediation http //membranes.nist.gov/Bioremediation/fig pages/f5.html (accessed September 2004). With permission.)... 

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