Spiral-wound oxygenators

Spiral-wound modules are much more commonly used in low pressure or vacuum gas separation appHcations, such as the production of oxygen-enriched air, or the separation of organic vapors from air. In these appHcations, the feed gas is at close to ambient pressure, and a vacuum is drawn on the permeate side of the membrane. Parasitic pressure drops on the permeate side of the membrane and the difficulty in making high performance hollow-fine fiber membranes from the mbbery polymers used to make these membranes both work against hollow-fine fiber modules for this appHcation. 

Figure 4.6. The two MBR types for bioartificial organs, a separate plasma and cells configuration. 1 plasma or culture medium feed, 2 oxygen feed, 3 oxygen exit, 4 plasma or culture medium exit, 5 living cells and medium, b perfusion MBR, 6 hollow fibers for oxygen feed, 7 external shell, 8 spirally wound polyester film, 9 anchored cells in a 3D matrix. Adapted from Legallais et al. [4.41].

Spiral-Wound Thin-FUm Composite System for the Economical Production of Oxygen-Enriched Air, Final report. Dept, of Eng., No. CS/4029H (Nov., 1983). 

Respiratory blood gas exchange occurs as the blood flows across the width of the spiral-wound membrane envelope the blood film formed is about 160 fA thick. Blood oxygen saturation difference on passing through... 

The most important application of RO is the desalinization of seawater. Since 1990, RO has become the dominant process for seawater desalinization. Seawater contains about 3.5 wt% dissolved salts and has an osmotic pressure of 24.1 bar. The preferred RO membrane for desalinization is a spiral-wound module of polyamide membrane operating at a feed pressure of 55 to 70 bar. With a transmembrane water flux of 365 kg/m2-day, this module can recover 45% of the water at a purity of 99.95 wt%. Atypical cylindrical module is 20 cm in diameter by 1.0 m long, containing 34 m2 of surface area. Such modules resist fouling by colloidal and particulate matter, but the seawater must be treated with sodium bisulfate to remove oxygen and chlorine. 

With regard to other significant factors, oxygen transfer can be singled out as of paramount importance. To enhance this transport step, we operated the spiral wound reactor counter-currently. In other words, a special provision was incorporated into the reactor design to allow flow of pure oxygen countercurrent... 

Babcock (88) discussed efforts to commercialize an ILM process to produce oxygen-enriched air. The spiral-wound modules contain an ILM consisting of a cobalt based carrier molecule In a low volatility organic solvent immobilized in a 4 ym thick mlcroporous film. 

Sealable valves are normally closed to prevent the entrance of oxygen from air. The valve allows excess generated hydrogen to be vented under a set pressure. Venting pressures range from a high of 25 to 40 psi for a metal-sheathed, spirally wound cell to 1 to 2 psi for a prismatic battery. 

The starved system, porous separator and oxygen recombination allow efficient space utilization for active material in the spiral-wound sealed lead-acid cell, resulting in a 15-50% increase in volumetric energy density over gelled-electrolyte systems. 

Plate-and-frame as well as spiral-wound modules house flat membranes. Capillary and hollow fibers are packed in larger bundles in a pressure vessel. Commercially relevant are flat membranes and hollow fibers. However, new developments in perovskite membranes for oxygen transport are based on tubular membranes as well. ... 

Hollow fiber refers to a membrane tube of very small diameter (e.g., 200 pm). Such small diameters enable a large membrane area per unit volume of device, as well as operation at somewhat elevated pressures. Hollow-fiber modules are widely used in medical devices such as blood oxygenators and hemodialyzers. The general geometry of the most commonly used hollow-fiber module is similar to that of the tubular membrane, but hollow fibers are used instead of tubular membranes. Both ends of the hollow fibers are supported by header plates and are connected to the header rooms, one of which serves as the feed entrance and the other as the retentate exit. Another type of hollow-fiber module uses a bundle of hollow fibers wound spirally around a core. 

---