Modules tubular

In contrast to capillaries and hollow fibers, tubular membranes are not self-supporting. Such membranes are placed inside a porous stainless steel, ceramic or plastic tube with the diameter of the tube being, in general, more than 10 mm. The number of tubes put together in the module may vary 

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Tubular membranes Tubular modules Tubular reactors Tubulates b-Tubulin Tubulin Tuffs Tufperm Tufprene... 

Tubular Modules. Tubular modules are generally limited to ultrafiltration appHcations, for which the benefit of resistance to membrane fouling because of good fluid hydrodynamics overcomes the problem of their high capital cost. Typically, the tubes consist of a porous paper or fiber glass support with the membrane formed on the inside of the tubes, as shown in Figure 24. 

A third factor is the ease with which various membrane materials can be fabricated into a particular module design. Almost ah membranes can be formed into plate-and-frame, spiral, and tubular modules, but many membrane materials caimot be fabricated into hollow-fine fibers or capihary fibers. Finahy, the suitabiHty of the module design for high pressure operation and the relative magnitude of pressure drops on the feed and permeate sides of the membrane can sometimes be important considerations. 

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. 

TFF module types include plate-and-frame (or cassettes), hollow fibers, tubes, monoliths, spirals, and vortex flow. Figures 20-52 and 20-53 show several common module types and the flow paths within each. Hollow fiber or tubular modules are made by potting the cast membrane fibers or tubes into end caps and enclosing the assembly in a shell. Similar to fibers or tubes, monoliths have their retentive layer coated on the inside of tubular flow channels or lumens with a high-permeability porous structure on the shell side. 

For fibers or tubular modules, the feed is generally introduced into the inside of the tubes, or lumen, while permeate is withdrawn from the shell side. This flow orientation enhances the shear at the membrane surface for TFF operation. These modules may also be run at high conversion or NFF mode with the feed introduced on the outside of the tubes or shell side. In this case, the shell side offers greater surface area. 

A3/X°i, C° = X°3/X°, and 03= X 3/X°3. reverse osmosis system involving longitudinal feed flow pattern in the module (such as in spiral wound or tubular modules), let... 

Daud, W.R.W. 2006. Shortcut design method for reverse osmosis tubular module The effect of varying transmembrane pressure and concentration polarization. Desalination 201 297-305. 

BP and Kvaemer Process were finalizing the demonstration of their Compact Reformer Technology in 2001. This technology involves the integration of combustion, heat transfer and catalytic reaction within a simple tubular module. This reformer is about 30% lighter (in weight) than a conventional reformer of equivalent capacity90. 

These and tubular modules offer the low packing density (membrane area per unit volume). Typical packing density is less than about 45 -150 ft2/ft3 for plate-and-frame modules.22... 

Tubular modules are also used for specialty, high-solids applications typically found in the food and biological processing industries. Tubular modules range from Vi- to 1-inch (1.3 - 2.6 cm) in diameter with the membrane feed side on the inside of the tube. Packing densities run about 6 -120 fP/ft3.22... 

Figure 4.13 shows how a tubular module is assembled.23 These modules essentially resemble a shell-and-tube heat exchanger, with the RO feed water on the tube side and RO permeate on the shell side. The membrane tubes are supported by perforated stainless steel tubes through which the permeate exits. 

Hollow fiber membrane modules can be backwashed to remove foulants whereas tubular and most spiral configurations cannot be backwashed. Backwashing of traditional spiral-wound modules would break the glue lines holding the membrane leaves together or cause blistering and delamination of the membrane from the backing in both spiral and tubular modules (TriSep Corporation has recently developed a back-washable, spiral-wound module (SpiraSep—US patent 6,755,970), that is used in immersed systems see below). 

Microfiltration membranes are commonly used in MBRs to separate sohds from water. The fluxes are very low, often below critical flux, and at low pressures when hollow fibers are used, backflushing is added to prevent or reduce flux decrease. MBRs are discussed in detail in Section 35.6.3.2, tubular modules with MF membranes have also been tested in the pulp and paper industry. 

Because high fluxes and the abdity to process streams containing suspended solids and fibers are often wanted in the pulp and paper industry, high-shear modules have been developed. Currently existing high-shear modules, excluding tubular modules, are modified plate and frame constructions. Both a cross-rotational module from Metso Paper and a vibration enhanced module (VSEP) from New Logic Inc. have been industrially used or tested in pulp and paper industry applications [48-51]. 

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