Membrane capacity

Competing Processes Membranes are not the only way to make these separations, neither are they generally the dominant way. In many apphcations, membranes compete with ciyogenic distillation and with pressure-swing adsorption in others, physical absorption is the dominant method. The growth rate for membrane capacity is higher than that for any competitor. 

When assessing the potential for RO as an RW treatment option and reviewing standard plant specifications, it is important to compare the rated membrane capacity against the available water source to be treated. Reported RO membrane capacity may be based on a temperature of 77 °F (25 °C) and perhaps only a 1,000 ppm TDS RW. This level of TDS may be much lower than the potential source of RW and the temperature also may vary, making corrections necessary. At lower water temperatures, the viscosity increases and the RO flux decreases (output decreases). This increases the number of membranes required to provide the desired flow. 

Another option to increase capacity is to limit the amount ofload produced at the ends of the panel. It is often unnecessary to develop the full membrane capacity of the panel in order to resist the blast load. An analysis may be performed to determine the actual maximum resistance in the pane and size the connections for this load. Use of a flexible support will also limit the magnitude of load occurring at the ends of... 

A loss of the deionized water supply occurred during a workup test. Increased water usage for feed mixing, coupled with reduced membrane capacity while operating with colder water during the winter months, caused the deionized water supply to drop. 

Asahi Kasei adding battery membrane capacity. Nikkei Net Interact. http //www.nni.nikkei.co.jp/AC/TNKS/ Nni20030806D06JFA23.htm, August 7, 2003. 

For a highly concentrated product, a large system hold-up volume increases the potential for product loss. For concentration/diafiltration operations, scale-up may require re-optimization of process parameters, especially if membrane capacities are changed. However, every effort should be made to keep recirculation flux constant with similar inlet and outlet pressures. 

Once process design is complete and each of the process steps characterized, the process is ready for scale-up to pilot or manufacturing scale. A spreadsheet template for scale-up calculations is important and provides a mass balance of buffer volumes, column volumes, priming volumes, product volumes, and waste volumes as well as the tank size and column size. Product volumes can be expressed relative to column volume or can be calculated from a constant concentration, depending on the process step. In addition, starting volumes and titers of conditioned medium as well as step yields and gel or membrane capacity are necessary to cal-... 

Figure 3. Membrane capacity (Curve I) and conductivity (Curve 2) of squid giant axon at various frequencies. Note anomalous behavior at low frequencies.

Figure 5. Membrane capacity per unit area of squid giant axon as a function of the length of the electrodes (29) ((upper scale) electrode length in mm (lower scale) inverse of length in mm1)...

Berkowitz, G. C. Barnes, F. S. The effects of nonlinear membrane capacity on the interaction of microwave and radio frequencies with biological materials. IEEE Trans. Microwave Theory Tech., 1979, MTT-27, 204-207. 

MA systems can easily add a module to increase membrane capacity or resolution. Alternatively, the series addition of a traditional chromatography column for improvement of capacity or resolution is seldom practiced. Thus, membrane chromatography offers the chromatographer a new flexibility of easy expansion of inadequate systems. Alternatively, the easy connectibility also enables a simple way to couple multiple units of different chemistries for a mixed-mode separation.43 The next section describes these configurations in greater details. 

Some of the different ultrafiltration processes within the four process combinations include diafiltration as well. When diafiltration was included at a stage, the sequence, ultrafiltration - diafiltration - ultrafiltration, was used in order to obtain a high separation efficiency and membrane capacity (8). 

The design shown in Fig. 9.7 is from a patent filed by Union Carbide in 1964 (U.S. Patent 3,336,730) [12]. According to a paper published by the inventors [13], Union Carbide had a membrane capacity for separating 10 milUon cubic feet (25 tons) of hydrogen per day in operation by 1965. At that time. Union Carbide used sheets of palladium-silver alloys approximately 1 ft x 1 ft square (30.5 x 30.5 cm)... 

Equation (5.2) implies that when summation of all the fluxes (Ji) of charged species (Zi) across the membrane leading to charging of the membrane capacity has concluded a quasi-equilibrium with a (approximately) constant Vm or Aij/ is attained. Its value depends on the difference in chemical potential Afj, ) of all transported species and on the affinities of coupled chemical reactions. This is embodied in the so-called Goldman diffusion equation but these relations are essentially transcendental with their explicit solution tractable only under defined conditions. If only one species permeates through the membrane, for example, a true equilibrium state is reached and the resulting transmembrane electrical potential difference is described by an expression known as the Nemst equation... 

Major UF food applications are in the dairy industry [18, 26, 31]. Dairy apphcations have the largest share of membrane capacity in the world with apphcations in whey processing — treatment of cheese whey for recovering milk proteins — and cheese-making. Membrane systems are also used for the production of whole and skim milk concentrates and in the manufacture of lactose-reduced milk products. 

Two disadvantages of this approach are the constraint on membrane-cell capacity and the fact that all the caustic can be regarded as the less marketable mercury-plant product. A larger membrane capacity can of course be installed to eliminate the first disadvantage and alleviate the second, but only at the expense of installing and operating an evaporator. 

Because of extremes in gas volume processed (turn-down ratio), the design basis in this case represents only half the anticipated peak volume. A second distillation plant will be required. With membranes, however, additional membrane capacity at the from end can be added as needed without additional equipmem required in the distillation section. Analyses of several associated gas forecasts indicate the exit gas fixm the first stage of membranes to be remarkably stable in composition and flow rate. This flexibility is not shown in a single case economic comparison. ... 

The effect is to decrease the net membrane capacity. The separation remains the same that is, as pertains to the foregoing interpreted conditions for perfect mixing. 

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