Membrane modules spiral wound

Spira.1- Wound Modules. Spiral-wound modules were used originally for artificial kidneys, but were fuUy developed for reverse osmosis systems. This work, carried out by UOP under sponsorship of the Office of Saline Water (later the Office of Water Research and Technology) resulted in a number of spiral-wound designs (63—65). The design shown in Figure 21 is the simplest and most common, and consists of a membrane envelope wound around a perforated central coUection tube. The wound module is placed inside a tubular pressure vessel, and feed gas is circulated axiaUy down the module across the membrane envelope. A portion of the feed permeates into the membrane envelope, where it spirals toward the center and exits through the coUection tube. 

Configurations used include tubes, plate-and-frame arrangements and spiral wound modules. Spiral wound modules should be treated to remove particles down to 20 to 50. im, while hollow fiber modules require particles down to 5 im to be removed. If necessary, pH should be adjusted to avoid extremes of pH. Also, oxidizing agents such as free chlorine must be removed. Because of these restrictions, reverse osmosis is only useful if the wastewater to be treated is free of heavy contamination. The concentrated waste material produced by membrane processes should be recycled if possible but might require further treatment or disposal. 

Y. Kamiyama, N. Yoshioka, K. Matsui and E. Nakagome, New Thin-film Composite Reverse Osmosis Membranes and Spiral Wound Modules, Desalination 51, 79... 

Figure 4.10 Trichloroethane enrichment [ln(l — 1/E)] as a function of permeate flux Jv in pervaporation experiments with silicone rubber membranes in spiral-wound modules using solutions of 100 ppm trichloromethane in water [15]. Feed solution flow rates are shown...

In the case of pervaporation of dissolved volatile organic compounds (VOCs) from water, the magnitude of the concentration polarization effect is a function of the enrichment factor. The selectivity of pervaporation membranes to different VOCs varies widely, so the intrinsic enrichment and the magnitude of concentration polarization effects depend strongly on the solute. Table 4.2 shows experimentally measured enrichment values for a series of dilute VOC solutions treated with silicone rubber membranes in spiral-wound modules [15], When these values are superimposed on the Wijmans plot as shown in Figure 4.12, the concentration polarization modulus varies from 1.0, that is, no concentration polarization, for isopropanol, to 0.1 for trichloroethane, which has an enrichment of 5700. 

Figure 5.28 Simplified flow schemes of (a) a conventional and (b) Mobil Oil s membrane solvent dewaxing processes. Refrigeration economizers are not shown. The first 3 million gallon/day commercial unit was installed at Mobil s Beaumont refinery in 1998. Polyimide membranes in spiral-wound modules were used [41-43]...

Flat-Sheet Membranes and Spiral-Wound Modules... 

The investment in time and equipment to develop a new membrane material in a high-performance hollow fine fiber or capillary form is far larger than that required to develop flat-sheet membranes, and many materials cannot be formed into fiber modules at all. For this reason, flat-sheet membranes, formed into spiral-wound modules, are used in many niche applications which cannot support the development costs associated with fiber modules. Spiral-wound modules are also competitive in the natural-gas processing area, where their general robustness is an asset. 

Figure 8.12 Block diagram and photograph of a contained in the horizontal pressure vessels, membrane fuel-gas conditioning unit (FGCU) The unit produces 0.5-1.0 MMscfd of clean gas. used for a field gas compressor engine (the unit Reproduced with permission from Ind. Eng. uses silicone rubber membranes in spiral-wound Chem. Res. 2008, 47(7), 2109-2121. Copyright modules). The membrane modules are 2008 American Chemical Society [17].

Suitable membranes are available as flat sheets or hollow fibers. These are packed in flat membrane stacks, spiral wound modules, or bundles of hollow fibers in order to achieve high surface area per unit volume. Short summaries of relevant membrane properties have been given [9, 13, 63]. 

Membrane processes are used to filter liquids. Instead of conventional filter materials (e.g. filter cloth, filter candles,) microporous membranes are employed with molecular size pores. First the industry had to learn how to manufacture membranes with controlled pore sizes. To optimise the filtration capacities specific filter structures had to be designed in which the liquid followed well defined flow patterns on one side of the membrane. Many different systems were developed for the varied applications, all having their advantages and also disadvantages, i.e. plate modules, tubular modules, spiral wound membranes, etc. Research and development in this field is far from being exhausted. Today membrane systems are available which are sufficiently resistant to chemical, mechanical and thermal stress. They are produced from plastic... 

Fig. 1 Membrane modules (from left to right at top row plate and frame module schematic, plate and frame module, spiral wound module schematic, spiral wound module at bottom row monoliths, tubular membranes, capillary membranes, hollow fibers. (Photos courtesy of http //www.niroinc.com/html/filtration/ftechsys.html.) (View this art in color at www. dekker.com.)...

Treatment of contaminated wastewater by pervaporation is superficially attractive, however, only a few commercial installations have been built. Phenol, which azeotropes with water at around 10wt%, is typically recovered by extraction in large plants, where measures to eliminate extractant loss can be economically applied. Pervaporation is an attractive and cost competitive alternative for small plants. Organophilic membranes in spiral wound modules are used in these applications. 

Petersen, R.J. Cadotte, J.E. Forester, R.H. and Buettner, J.M. "Development of Novel Polypiperazineamide Membranes in Spiral Wound Modules", Contract No. 14-34-0001-8547 to Office of Water Research and Technology, 1979. 

Membranes in Spiral Wound Modules", NTIS Report No. PB83-191775 loc. cit. (Oct. 1982). 

For industrial applications, large surface areas are obtained using modules with many tubular or hollow-fiber membranes or by using large sheets in a spiral-wound arrangement. Tubular membranes are 5 to 25 mm inside diameter and up to 3 m long. Hollow-fiber UF membranes have diameters of 0.2 to 2 mm, and thousands of fibers are sealed in each cylindrical module. Spiral-wound modules of the type used for RO are widely used for UF. 

Kawada I., Inoue K., Kazuse Y., Ito H., Shintani T., Kamiyama Y. (1987), New thin-film composite low pressure reverse osmosis membranes and spiral wound modules. Desalination, 64, 387-401. 

The commercial RO modules that have appeared in the literature since 1977 are summarized in Table 3.2 together with the typical operating conditions and performance. Some of them might no longer exist in the market. From the table, it is clear that the majority of high-salt-rejection RO membranes are spiral-wound aromatic PA-TFC membranes with a noted exception of Toyobo that is based on CTA hollow fiber. The reason might be easier cleaning of the spiral-wound module, on one hand, and chlorine resistance of CA, on the other. 

Figure 15.1 A gas treatment skid for hydrogen recovery from the 1980 s containing cellulose acetate membranes as spiral wound modules. Image courtesy of W. R. Grace, Copyright (1988) W. R. Grace...

Membrane systems to remove acid gas from the natural gas emerged more than three decades ago. Today about half a dozen venders provide membrane systems for natural gas upgrading. Amongst them are UOP (Separex and Grace), who uses cellulose acetate spiral wound module and Natco (Cynara) who uses cellulose acetate hollow fiber membrane modules. Ube, Air Liquide and Air Products offer polyimide hollow fiber membrane modules, and MTR produces perfluoropolymer membranes in spiral wound modules. 

Membrane modules have found extensive commercial appHcation in areas where medium purity hydrogen is required, as in ammonia purge streams (191). The first polymer membrane system was developed by Du Pont in the early 1970s. The membranes are typically made of aromatic polyaramide, polyimide, polysulfone, and cellulose acetate supported as spiral-wound hoUow-ftber modules (see Hollow-FIBERMEMBRANEs). 

Fig. 22. Multileaf spiral-wound module, used to avoid excessive pressure drops on the permeate side of the membrane. Large, 30-cm diameter modules may have as many as 30 membrane envelopes, each with a membrane area of about 2 m. ...

In reverse osmosis, most modules are of the hollow-fine fiber or spiral-wound design plate-and-frame and tubular modules are limited to a few appHcations in which membrane fouling is particularly severe, for example, food appHcations or processing of heavily contaminated industrial wastewater. 

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