Electrodialysis flow schematics

Figure 10.17 Flow schematic of electrodialysis systems used to exchange target ions in the feed solution, (a) An all-cation exchange membrane stack to exchange sodium ions for calcium ions in water softening, (b) An all-anion exchange membrane stack to exchange hydroxyl ions for citrate ions in deacidification of fruit juice...

Figure 8.17. Schematic flow-diagram for an electrodialysis stack...

FIG. 19 Schematic flow diagram for the production and purification of fermentation-derived acetic acid, as modified from Office of Industrial Technologies (2003). Unit operation identification items AF, anaerobic fermentation DI, distillation ED, electrodialysis EV, evaporation MF, microfiltration PV, pervaporation-assisted thermal cracking. 

The membranes in an electrodialysis cell are separated by spacer gaskets as indicated in Figure 5.3, which shows schematically the design of a so-called sheet flow electrodialysis stack. The spacer gasket consists of a screen that supports the membranes and controls the flow distribution in the cell and a gasket that seals the cell to the outside and also contains the manifolds to distribute the process fluids in... 

Stack design in bipolar membrane electrodialysis The key component is the stack which in general has a sheet-flow spacer arrangement. The main difference between an electrodialysis desalination stack and a stack with bipolar membranes used for the production of acids and bases is the manifold for the distribution of the different flow streams. As indicated in the schematic diagram in Figure 5.10 a repeating cell unit in a stack with bipolar membranes is composed of a bipolar membrane and a cation- and an anion-exchange membrane and three flow streams in between, that is, a salt... 

To illustrate the concentration polarization phenomenon, we consider an infinitely long electrodialysis cell pair having parallel channels in which the flow is fully developed and laminar. The qualitative behavior of the development of the salt concentration and potential distributions along the channels of a dialysate and concentrate cell pair are shown schematically in Fig. 6.2.3 for the case where the inlet salt concentrations are the same in both channels (Probstein 1972). 

Fig. 9 Schematic diagram of a) a tortuous-path electrodialysis spacer gasket, and b) a sheet-flow clectrodialysis spacer gasket...

In stack designs employing the sheet-flow principle, a peripheral gasket provides the outer seal and the solution flow is approximately in a straight path from the entrance to the exit ports which are located on opposite sides in the gasket. This is illustrated in Figure 7 a) which shows the schematic diagram of a sheet-flow spacer of an electrodialysis stack. 

In plate-and-frame systems, such as in electrodialysis, turbulence promoters are introduced to increase the mass transfer. Figure VII - 8 is a schematic drawing of a flow channel in which corrugations have been introduced and where A1 is the distance between successive corrugations. 

Fig. 15.7 Schematic representation of the desalination of water by electrodialysis. A refers to the anion-exchange membrane, and C refers to the cation-exchange membrane. The applied voltage attracts the ions from the low-flow water stream into the high-flow wastewater...

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