Total membrane area

FIG. 22-77 Influence of feed purity on total membrane area when the residue gas at fixed purity is the product, Feed-gas volume is constant, CO2/CH4 cellulose-acetate membrane, (X = 21, Courtesy VP R. Grace.)... 

FIG. 22-79 Effect on permeate of dividing a one-stage separation into two equal stages having the same total membrane area. Compositions of A, D, and F are equal for both cases. Cowiesif VF R. Grace. )... 

An integrated proof-of-concept (POC) size fluidized-bed methane reformer with embedded palladium membrane modules for simultaneous hydrogen separation is being developed for demonstration (Tamhankar et al., 2007). The membrane modules will use two 6 in. X 11 in. Pd-alloy membrane foils, 25-pm thick, supported on a porous support. The developmental fluidized-bed reactor will house a total of five (5) membrane modules with a total membrane area of about 0.43 m2 and is scheduled for demonstration by September 2007. 

Let A be the total membrane area (m ) and dA an infinitesimal increase of A in the blood flow direction. Oxygen saturation y (-) and oxygen partial pressure p (mmHg) increase by dy and Ap, respectively, in the membrane area cL4. The increase in the oxygen content of blood cLV (cm cm rnin ) on dA is given by... 

In a hollow-fiber-type membrane blood oxygenator, the blood flows outside and across the hollow fibers. The total membrane area (outside fibers) is 4 m . From the data on physical oxygen absorption into water at 20 °C, the following empirical equation (a) for the water-phase oxygen transfer coefficient (cm min ) in this particular oxygenator at 20 °C was obtained. 

The required total membrane area is subdivided into three zones 1, 2, and 3 by the ranges of oxygen saturation y. 

The total membrane area required is 4.00 m. Thus, this oxygenator with Im membrane area can oxygenate 5lmin" of blood, as assumed. 

A hollow-fiber-type membrane blood oxygenator, in which blood flows inside the hollow fibers, has a total membrane area (outside fibers) of 4.3 m". The inside diameter, membrane thickness, and length of the hollow fibers are 200 pm, 25 pm, and 13 cm, respectively. When venous blood (Ht = 40%, pQ. = 36 mmHg)... 

In a hoUow-fiber-type hemodialyzer of the total membrane area (based on o.d.) A = 1 m , 200 cm min of blood (inside fibers) and 500 cm min of dialysate (outside fibers) flow countercurrently. The overall mass transfer coefficient for urea (based on the outside diameter of the hollow fiber) is 0.030 cm min . Estimate the dialysance for urea. 

As expected, due to the small headgroup area of cholesterol (Achol = 40 A2, while ADOpc = 72 A2) [40, 41], the membrane charge density of DOTAP/DOPC/ Chol-DNA complexes increases with cholesterol content. Exchanging DOPC for cholesterol reduces the total membrane area while the membrane charge, given by dotap = 0-3, remains constant thus cM increases. A particularly strong increase in cM occurs for Choi > 0.4, where part of the cholesterol is not incorporated in the complex. This results in an increased <2>DOTap and thus aM. 

In this chapter, the use of membranes in medical devices is reviewed briefly. In terms of total membrane area produced, medical applications are at least equivalent to all industrial membrane applications combined. In terms of dollar value of the products, the market is far larger. In spite of this, little communication between these two membrane areas has occurred over the years. Medical and industrial membrane developers each have their own journals, societies and meetings, and rarely look over the fence to see what the other is doing. This book cannot reverse 50 years of history, but every industrial membrane technologist should at least be aware of the main features of medical applications of membranes. Therefore, in this chapter, the three most important applications—hemodialysis (the artificial kidney), blood oxygenation (the artificial lung) and controlled release pharmaceuticals—are briefly reviewed. 

Total membrane area 5.1 mm x 5.1 mm Total device size 7 mm x 7 mm... 

Here Atot is the total membrane area in a stack and Ncen is the number of cell pairs in a stack and i]im is the limiting current density that determines the maximum voltage that can be applied. All other symbols are identical as the ones in the Equations 5.21-5.27. 

There are two interconnected UF lines, each line contains 4 unit composed by 9 Zee Weed modules and the total membrane area is 100 000 m2 [21]. 

Ultrafiltration experiments were carried using the same setup, except the flat-sheet membrane module had a filtration area 38 mm long, 29 mm wide, and 1.6 mm high, with a surface area of 11 cm2. The permeate side had 11 grooved channels that supported the membrane, leaving an effective filtration area of 6.4 cm2. However, the total membrane area including the supports was used in calculating the fluxes. The feed consisted of cellulase enzyme solution (5.0 g/L of supplied cellulase, unless noted otherwise). 

In the absence of suspended solutes or colloids, the pure solvent flux through an ultrafiltration membrane is directly proportional to the applied pressure difference and inversely proportional to the viscosity of the solvent and the membrane thickness. Transport within the pores occurs in the creeping flow regime, since kinematic viscosities of liquids are sufficient to make Re < C 1 for practical pore sizes. In the simplest case, the membrane can be considered to be a packed array of straight, equal diameter nonintersecting capillary tubes. The observed volumetric flux, nAvA (cc/sec cm2), equals the product of the mass flux of solvent based on the total membrane area, nA... 

The last equation reveals that estimates for P can be obtained in an experimental setup if the permeation rate q (/,) and the total membrane area A available for transport are measured and the drug concentration c (t) in the donor compartment remains practically constant. What is implicit from all the above is... 

FIGURE 8 Arrangement of multiple radial flow modules to increase capacity and flow rate. Two 8 m2 modules were connected in parallel, with one 4 m2 module in series, in conjunction with a final I m2 module in series. Total membrane area is 21 m2. (Adapted from Journal of Chromatography, Vol. 852, W. Demmer and D. Nussbaumer, Large-scale membrane adsorbers, 73-81. Copyright 1999 with... 

A), A the total membrane area (m ), A the potential difference (V) applied to the EDBM unit. 

In 2002, Eurodia has supplied chelating resins and bipolar ED plant for 1700 ton/year acetic acid production, which represents 450 m as total membrane area (Figure 21.38). The purpose of this application is to recover acetic acid from sodium acetate waste effluent and to reuse it in the process. The feed flow of sodium acetate concentration at 210 g/L is 1.5 m /h and 91.5% is converted in acid. Acetic acid is recovered at 3 N and sodium hydroxide at 1.5 N. This plant was built according to pharmaceutical standards. 

In general, every stream must be tested to determine design factors such as the specific membrane polymer, membrane element design, total membrane area, applied pressure, system recovery, flow conditions, membrane element array, and pretreatment requirements. 

Membrane Diameter (mm) Number of Membranes Total Membrane Area (m2) Membrane Packing Density (m2/m3)... 

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