Spiral wound membrane modules commercial available module

Pleated ultrafiltration module. The axial filter is convenient for experiments, in that volumes small relative to ordinary ultrafiltration systems can be studied and in that pumping of viscous solutions is limited to that necessary to replace filtrate or concentrate bled from the chamber, rather than that necessary to maintain desired cross flow velocities. There is no obvious reason it could not be scaled up to moderate sizes for practical separations, but so far as we know, no large-volume axial filters are available. For the operations of interest, any of the commercial ultrafiltration systems would be candidates. We have tested one module, recently developed by Gelman, which incorporates a pleated membrane (Figure 5), with somewhat more open feed passages than those of spiral-wound membranes, and which allows backwashing. Other applications of the module were discussed at this symposium by A. Korin in a paper coauthored by G. B. Tanny, and a written account is presumably in these proceedings. 

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 commercially available 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). 

Microfiltration membranes are similar to UF membranes but have larger pores. Microfiltration membranes are used to separate particles in the range of 0.02-10 pm from liquid or gas streams. Commercial MF membranes are made from a wide variety of materials including polymers, metals, and ceramics. A wide variety of membrane module designs are available including tubular, spiral wound, pleated sheet, hollow fiber, and flat sheet designs. Some modules are best suited for crossflow filtration, and others are designed for dead-end filtration. In dead-end filtration, the feed liquid flows normal to the surface of the membrane, and retained particles build up with time as a cake layer on the membrane surface or within the pores of the membrane. 

CA blend membranes for gas separation are commercially available from Envlrogenlcs Systems Co. (El Monte, CA), Separex Corp. (Anaheim, CA) and Grace Membrane Systems (Houston, TX), and are applied In spiral-wound modules for the separations of acidic gaseous components from natural gas, for the recovery of carbon dioxide In enhanced oil recovery processes for gas dehydration or the separation of hydrogen from carbon monoxide (21-23). 

A large-scale natural gas producer made available a test skid that would allow for membrane prodncts to be demonstrated under real field conditions. Commercial CA membranes from both Grace and another supplier and the developmental membrane were delivered to the field as full-scale 20 cm (8 inch) diameter spiral wound modules. 

PRO has seen significant progress in the past few years, mainly thanks to the development of better and better membranes. However, experimental activity has been so far mostly limited to laboratory-scale testing of commercially available RO and FO membranes [6,7, 13,14] or prototype lab-cast membranes [12,15,16]. In particular, experiments have been reported where commercial FO spiral-wound modules were used the maximum power densities reported as inferred from experimental measurements, using seawater-equivalent as the concentrated stream, are 0.5 W/m in a commercially available spiral-wound module [14] and 3.5 W/m with a prototype, lab-cast TFC membrane [12]. 

Membranes are never sealed-up as a single flat sheet, beeause its low surface area per imit volume ratio often results in high investment costs. Modular configurations are fabricated to enable large membrane surfaces to be housed in the smallest possible volumes. Their choice depends on cost, module packing density, risk of fouling and feasibility of cleaning. The most common commercially available membrane modules include plate-and-frame, tubular, spiral-wound and hollow fiber elements. 

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