Both open-ended modules hollow-fiber membrane

Toyobo s newest innovative RO module builds on the proven reliability of the HM-type module. The new technology is based on both open-ended (BOE) hollow-fiber membrane stmctures versus single open-ended hoUow-fiber membrane stractures. The... 

Hollow fine fiber membranes are extremely fine polymeric tubes 50-200 micrometers in diameter. The selective layer is on the outside surface of the fibers, facing the high-pressure gas. A hollow-fiber membrane module will normally contain tens of thousands of parallel fibers potted at both ends in epoxy tube sheets. Depending on the module design, both tube sheets can be open, or as shown in Figure 8.1, one fiber end can be blocked and one open. The high-pressure feed gas flows past the membrane surface. A portion of the feed gas permeates the membrane and enters the bore of the fiber and is removed from the open end of the tube sheet. Fiber diameters are small because the fibers must support very large pressure differences feed-to-permeate (shell-to-bore). 

The modules employed in a membrane fractionating column must be different from those used in cascades in hollow fiber modules, for example, the fibers cannot be U-shaped and must be open at both ends. In Reference 5, a module is described based on this principle. 

The two most common separation modules for the gas and liquid separation processes are the hollow fiber and spiral wound constmaions shown in Figure 7. The hollow fiber module consists of hollow fibers placed in a cylindrical pressure chamber and encapsulated in a thermosetting pol)uner (e.g., epoxy) at both ends. The feed stream is usually on the shell side of the module, and the permeate stream is collected from the open ends of the hollow fibers. Optionally, the feed stream can be delivered to the bore of the hollow fibers with the permeate stream on the shell side. The spiral wound module comprises repeating layers of a spiral wound sheets constmetion which contains alternating layers of the membrane, feed stream spacer, membrane, and permeate stream spacer. Proper sealing of the spiral wound layer construchon allows for separation of the feed stream horn the permeate stream and flow of the permeate stream to the permeate stream outlet. 

Larger membrane modules having surface area about 700 - 800 cm were also prepared and tested. These modules were constructed using about 80 -100 PEI hollow fibers of 35 cm length. These fibers were potted at both ends using epoxy resin into 11/4 inches diameter steel tube having an outlet on the side. The module was sealed at both ends by means of steel end caps fitted with 0-rings. Fiber lumens were open at both ends. 

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