Spiral wound module technology

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. 

Figure 3.44 Schematic of a spiral-wound module [115] installed in a multimodule pressure vessel. Typically four to six modules are installed in a single pressure vessel. Reprinted from Reverse Osmosis Technology, B.S. Parekh (ed.), Marcel Dekker, New York (1988), p. 81, by courtesy of Marcel Dekker, Inc.

When discussing membrane preparation, not only must the physical structure be considered, but one must also consider the membrane form or shape. In an effort to combat concentration polarization and membrane fouling and to maximize the membrane surface area per unit module volume, membranes are produced in the form of flat sheets (used either In plate-and-frame or spiral wound modules), supported and unsupported tubes, and hollou fibers. Although much of the technology associated with membrane development and membrane production Is closely guarded as proprietary Information, some of the details are beginning to appear in the literature (6,9-13,16-20). 

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. 

Fig. 2.3 Spiral-wound module (used with permission of Membrane Technology, Research, Inc.)...

Early designs for spiral wound modules or hollow fibre bundles came from the RO industry. Modules for treatment of namral gas have also borrowed from these technologies. A skid containing spiral wound modules built in the 1980s for gas treatment is shown in Figure 15.1. This early array had six high pressure housings while cnrrent installations for natural gas treatment can have hundreds of mbes. 

Winter D., Koschikowski X, Duever D. (2011), Spiral wound modules for membrane distillation modeUing,vahdation and module optimization, Proc. Int. Workshop on Membrane Distillation and Related Technologies, Ravello (So, Italy), Oct. 9-12, pp. 58-59. 

Composite membranes are made in sheets or rolls and fabricated into large-membrane-area membrane modules for use in industrial systems. GKSS, the main European suppher of vapor—gas separation units, packages its membranes into plate-and-fiame modules. Membrane Technology and Research, Inc. (MTR, Menlo Park, CA) the main U.S. producer, uses spiral-wound modules. 

It is interesting to note that the open literature indicates that the applieation of UTDR eharac-terization to membrane science and technology has taken place entirely in university laboratories. Relatively few of these studies have applied UTDR eharacterization to commercial membrane modules. Moreover, UTDR has been used on only small-seale commercial modules such as the 2521 spiral-wound module, whieh ean be studied in the laboratory. Clearly, only industry has the capability to explore the potential of UTDR for large-scale membrane modules and processes. Hence, the authors strongly recommend cooperative efforts between industry and university researchers in order to utilize the fiill power of UTDR as a characterization tool for developing improved membranes and membrane processes. 

The main building block of a membrane reactor system is the module, which as a unit operation bears more resemblance to a membrane unit than to a traditional reactor. For commercial apphcations, it is desirable to fabricate membranes into a modular form that maximizes both productivity and selectivity. The most common commercial membrane geometries are flat sheet and tubular, and currently there are five module types namely, plate-and-frame and spiral-wound modules, based on flat membranes, and tubular, capillary and hollow-fibre modules, based on tubular membrane geometries. The module types of most relevance to siUca membrane modules and membrane reactors are the plate-and-frame and tubular types. The inflexibility of silica membranes prevents them from being used in a spiral-wound set-up and the technology to produce capillary and hoUow-fibre membrane geometries has not been adequately explored for sihca membranes. Plate-and-frame modules are easily constructed by... 

S.S. Kremen, Technology and Engineering of ROGA Spiral-wound Reverse Osmosis Membrane Modules, in Reverse Osmosis and Synthetic Membranes, S. Sourirajan (ed.), National Research Council Canada, Ottawa, Canada, pp. 371-386 (1977). 

Figure 21.12 Marketed equipments for membrane emulsification, (a) Plant for crossflow membrane emulsification produced by SPG Technologies Co. Ltd (http //www.spg-techno. co.jp/) (b) spiral-wound metallic membrane module produced by Micropore Technologies (http //www.micropore.co.uk/).

Over the course of development of the membrane technology, RO module designs, as shown in Figure 8.4, evolved. They are tubular, plate-and-frame, spiral wound, and hollow hne-hber modules. In the tubular design, the membrane is lined inside the tube which is made of ordinary tubular material. Water is allowed to pass through the inside of the tube under excess pressure causing the water to permeate through the membrane and to collect at the outside of the tube as the product or permeate. The portion of the influent that did not permeate becomes concentrated. This is called the concentrate or the reject. 

FIGURE 4.20 A spiral wound membrane module. (From Mulder M., Basic Principles of Membrane Technology. 2nd ed. Dordrecht, Kluwer Academic Publishers, 1996. With permission.)... 

Liquid impregnated (or immobilized) in the pores of a thin microporous sohd support is defined as a supported liquid membrane (SLM or ILM). The SLM may be fabricated in different geometries. Flat sheet SLM is useful for research, but the surface area to volume ratio is too low for industrial applications. Spiral-wound and hoUow-fiber SLMs have much higher surface areas of the LM modules (103 and 104 m /m, respectively [23]). The main problem of SLM technology is the stability the chemical stability of the carrier, the mechanical stability of porous support, etc. 

---