Permeate withdrawal

Spiral Wound. A spiral-wound cartridge has two flat membrane sheets (skin side out) separated by a flexible, porous permeate drainage material. The membrane sandwich is adhesively sealed on three sides. The fourth side of one or more sandwiches is separately sealed to a porous or perforated permeate withdrawal tube. An open-mesh spacer is placed on top of the membrane, and both the mesh and the membrane are wrapped spirally around the tube (Fig. 16). 

Spiral-wound cartridges are inserted ia series into cylindrical pressure vessels. Feed flows parallel to the membrane surfaces ia the channel defined by the mesh spacer which acts as a turbulence promoter. Permeate flows into the center permeate-withdrawal tube which is sealed through the housing end caps. 

Others have introduced hehcaUy wound or patterned fiber lay-up in the bundle geometries as a means for controlling and preserving the shell-side flow patterns within the module [27]. The use of hollow-fiber fabrics has also been proposed as a means for precision spacing of the hollow-fibers within the membrane module [28-31]. Many of these are assembled around a central mandrel that also serves as a fluid conduit for feed introduction or product or permeate withdrawal. Modules assembled in this fashion also accommodate distributors and baffles inserted within the fiber pack to aid in the direction and control of the flow sheU-side flow pattern. 

Differential Permeation with Point Permeate Withdrawal... 

Figure 5.1 Differential permeation with point permeate withdrawal.

Differential Permeation ivith Point Permeate Withdrawal i 175... 

By analogy with Section 5.6 of Chapter 5, for differential permeation with point permeate withdrawal, the equation to be integrated is... 

Table A5.1 Excel Spreadsheet Designators and Formulas for Differential Permeation with Point Permeate Withdrawal Calculations...

Following this, more rigorous derivations for differential permeation are pursued. That is, permeation is viewed as a continuum rather than an operation in discrete stages or cells. In the first case to be considered, there is continuous point permeate withdrawal in another case, the more general case of permeate flow is analyzed, both concurrently and coun-tercurrently. 

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See also in sourсe #XX -- [ ]

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