Hollow-fibre modules

Fig. 16.19. Hollow-fibre module and, inset, a single fibre.

Kcurentjes et al. (1996) have also reported the separation of racemic mixtures. Two liquids are made oppositely chiral by the addition of R- or S-enantiomers of a chiral selector, respectively. These liquids are miscible, but are kept separated by a non-miscible liquid contained in a porous membrane. These authors have used different types of hollow-fibre modules and optimization of shell-side flow distribution was carried out. The liquid membrane should be permeable to the enantiomers to be separated but non-permeable to the chiral selector molecules. Separation of racemic mixtures like norephedrine, ephedrine, phenyl glycine, salbutanol, etc. was attempted and both enantiomers of 99.3 to 99.8% purity were realized. 

Geist, A., Weigl, M., Gompper, K. 2004. Hydrometallurgical minor actinide separation in Hollow Fibre Modules. ATALANTE 2004 Advances for Future Nuclear Cycles, June, Nimes, France. 

Escalante, H. and Irabien, A. (2001) Separation/concentration of L-phenylalanine in hollow fibre modules, decrease of the extraction rate, in Solvent Extraction for the 21st Century (eds M. 

Guilt, C.M. Air gap membrane distillation 2. Model validation and hollow fibre module performance analysis, Sep. Purif. Technol., 43(3), 245, 2005. 

Wickramasinghe SR, Semmens Ml, and Cussler EL. Hollow-fibre modules made with hoUow-fibre fabric. 7. Membr. Sci. 1993 84(1) 1-14. 

Geist, A., Weigh M., and Gompper, K., Minor actinide partitioning hy hquid-hquid extraction using a synergistic mixture of his (chlorophenyl)dithiophosphinic acid and TOPO in a hollow fibre module for americium(III) and lanthanide(ni) separation. Sep. Sci. Tech., 2002, 37 3369-3390. 

Long diffusion distance for nutrients and oxygen in hollow-fibre modules... 

In general, membrane-supported liquid-liquid extraction is offered as a micro-porous hollow fibre module (Fig. 2.23). The membrane contactor contains thousands of micro-porous hollow fibres knitted into an array that is wound around a distribution tube with a central baffle. The hollow fibres are arranged in a uniform open packing allowing the utilisation of the total membrane surface area. The liquid flows over the shellside (outside of the hollow fibre), is introduced through the distribution tube and moves radially across the array of hollow fibres and then around the baffle and is carried out by the collection tube. 

A further increase of the packing density (surface area-to-volume ratio) is obtained with experimental hollow-fibre modules, as shown in Fig. 2.9. They consist of long, hollow fibres with an internal diameter ranging from 40 to 300 pm and wall thicknesses of 10-100 pm. Surface area-to-volume ratios of more... 

Lipniski, F. Field, R.W. Mass transfer performance for hollow fibre modules with shell-side... 

Luque, S. Mallubhotla, H. Gelhert, G. Kuriyel, R. Dzengeleski, S. Pearl, S. Belfort, G. A new coiled hollow fibre module design for enhanced microfiltration performance in Biotechnology. Biotechnol. Bioeng. 1999, 65, 247-257. 

A Memcor microfiltration unit with automated air backflush was used for pretreatment. The membrane area of the hollow fibre module is 1 m. ... 

Dead-end hollow fibre modules are used in UF and MF water treatment applications. They come in two designs, pressurised and submerged, as shown in Figure 1.21. Specifications of various commercial modules are provided in Table 6.14. 

Hollow-fibre membrane modules are similar to the capillary type described above, but with fibres of outside diameters ranging from 80 to 500 pm. It is usual to pack a hollow-fibre module with many hundreds or thousands of these fibres, thus membrane area per unit volume is extremely hi. It should be apparent that filtration using hollow-fibre modules is only realistic with process fluids prefiltered to prevent fibre blockage fins limits the technology and it is applied mainly in UF. Also used in uhrafiltration is a spiral-wound membrane module which is often compared to a Swiss roD. The membrane and a spacer are wound round a former, with an appropriate permeate spacer flow is introduced and removed from the ends. This module design is not appropriate for solid-liquid separation, even when filtering colloids, because of the possibility of flow channel blockage and so it will not be discussed any finther. 

Membranes in the form of hollow fibre modules are used commonly for gas dehydration. In comparison to spiral wound modules made from flat sheet membranes, hollow fibre membrane modules contain more membrane surface area per unit volume thereby reducing the size of the module. Additionally, hollow fibre module manufacturing costs are lower [1] and hollow fibre designs easily permit permeate sweep. 

A hollow fibre module can be operated in three different modes co-current, cross, or counter-current flow. In co-current flow, the permeate flows in the same direction as the feed and retentate. In cross-flow, the permeate flows perpendicularly to the feed and retentate while in countercurrent flow the permeate flows in the opposite direction. The countercurrent flow pattern gives the best performance as the driving force for transport is maximized along the module length. One can produce an arbitrarily high purity... 

The patent literature describes three primary methods for introducing sweep from the retentate product into the shell of a hollow fibre module. 

The performance of membrane processes also relies on the use of correct module configurations (Zhou Smith, 2002). Typical commercial manbrane geometries are flat sheet and mbular. There are five module types plate-and-flame and spiral-wound modules, based on flat membranes, and tubular, capillary and hollow-fibre modules, based on tubular membrane geometries (Basile, 2013). A qualitative comparison amongst some of the different model configurations is presented in Table 20.7. 

The analysis of a hybrid bioartificial membrane pancreas (HBMP) in which porcine islets of Langerhans were segregated in the shell side of a hollow fibre module, showed the importance of convective fluxes in determining reactor performance. A distributed parameter model, taking into account... 

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