Fiber unit processes

Research effort at Albany International Research Co. has developed unit processes necessary for pilot scale production of several species of reverse osmosis hollow fiber composite membranes. These processes include spin-dope preparation, a proprietary apparatus for dry-jet wet-spinning of microporous polysul-fone hollow fibers, coating of these fibers with a variety of permselective materials, bundle winding using multifilament yarns and module assembly. Modules of the membrane identified as Quantro II are in field trial against brackish and seawater feeds. Brackish water rejections of 94+% at a flux of 5-7 gfd at 400 psi have been measured. Seawater rejections of 99+% at 1-2 gfd at 1000 psi have been measured. Membrane use requires sealing of some portion of the fiber bundle for installation in a pressure shell. Much effort has been devoted to identification of potting materials which exhibit satisfactory adhesion to the fiber while... 

Selective separation and concentration of both cations and anions using water-soluble polymer solutions LM as carriers and hoUow-fiber units (artificial kidneys) as membrane barrier were tested. The authors termed the process as affinity dialysis [74]. Hollow fiber units of Spectrum Medical Industries, Inc. with fibers of 5000 molecular weight cutoff and 150 cm surface area from Spectrapor were used in the experiments. 

A more recent development is the use of UF for point-of-use processing. When UF is installed in the central system, the plastic (PVC) piping to the various rinse stations collects particles and leaches organics. A small 4 gpm hollow fiber unit at the rinse station removes all particles, colloids and organics down to an average size of 0.005 p. In some cases, these units are operated dead-ended with a periodic fast-forward flush to remove accumulated particles inside the hollow fibers. 

Because of the intimate coupling among sorption, crystallization and cavitation during SINC, one must examine all three to fully characterize the fiber treatment process. The preliminary results of our experimental investigations of PET exposed to methylene chloride at unit activity reveal several features of SINC not previously discussed in the literature. 

Polyaniline solutions for fiber spinning were prepared using the secondary amines HPMI and 4-methylpiperidine (4-MP) as stabilizers for the concentrated EB/NMP solutions. These reduced the EB more slowly than secondary amines such as 2-methylaziridine [43]. Polyaniline fibers were processed from dope solutions in which the concentration of EB base powder (M 150,000 g/mol) varied from 17.5 to 25 wt% polyaniline in the case of the HPMI/NMP or 20 wt% of EB base powder (M 200,000 g/mol) for the 4-MP. The stoichiometric ratio between the HPMI molecules and the EB tetramer repeat unit required to stabilize the dope solution was 1.1 1 whereas the 4-MP EB tetramer ratio was 1.2 1. The EB was mechanically stirred into the secondary amine/NMP solution until a smooth, lump-free solution was obtained. 

Quaternary calcium aluminate glass fibers were also downdrawn from preforms on a laboratory [9] and a development unit [41], Downdrawing is a valid, but costly, method for fiberizing fragile melts. In addition, only one of >500 compositions could be fiberized on a conventional melt fiberizing unit [17], This process is not suitable for fragile melts. 

Amylase and pectinase Polysulfone single-hollow-fiber unit BMR Fruit juice processing 35... 

Large surface area membrane modules such as hollow fiber units are often used in the production of low-alcohol beer, hemodialysis, or desalination. In all these processes the rate of transfer is believed to be governed by the concentration difference across the membrane, the molecular size, and the permeability characteristics of the membrane. A model that has shown some promise in correlating the amount removed as a function of flow rate is discussed below. 

Hasan, A. Teymouri, F. Laiveimo-Perez Dale, B.E. Ammonia Fiber Explosion Process (AFEX) A Rapid and Flexible Laboratory Scale Unit. 24 Symposium on Biotechnology for Fuels and Chemicals, Spring 2002. 

Fedorak PM. Microbial processes in the degradation of libers. In Blackburn RS, editor. Biodegradable and Sustainable Fibers. United Kingdom Woodhead PubUshing 2005. 

Production level, the direct line from raw material input to the finished stock which may include unit processes with some or all of the following objectives To break down the raw material into individual fibers, to separate fibers and contaminants, to separate fibers/solids and water, to treat the fibers, and to treat the residual contaminants. 

The unit processes in fiber preparation and their objectives are ... 

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