Bipolar membrane electrode configuration

Electrode plates or grids are assembled in stack of cells (see Fig. 2). There is no membrane separation between the electrodes. The electrodes are inserted inline directly into the water flow after the filtering unit. Monopolar, bipolar, and combined bipolar-monopolar electrode configurations are used. The required maximum chlorine production rate, for residential pools 2-3 g of CI2 per hour per 10 m of water, defines the size and number of cells. 

Cells usually have a bipolar configuration. The electrocatalysts are bonded to each side of the membrane (15), and the resulting SPE is a structurally stable membrane-electrode assembly as shown in Figure 1. A multi-layer package of expanded metal screens which presses up against the electrode on one side serves as the current collector and fluid distributor. 

In a single-cell configuration, there are no bipolar plates. The two plates on each side of the membrane electrode assembly may be considered as two halves of a bipolar plate. The fully functioning bipolar plates are essential for multicell configurations (as shown in the Figure 16), by electrically connecting the anode of one cell to the cathode of the adjacent cell. 

A unit fuel cell can be constructed using a membrane electrode assembly (MEA) and two bipolar plates as shown in Fig. 1(a). Multiple cells can be stacked up to obtain more power and such a configuration is shown in Fig. 1(b). The charge carriers and their flow direction are identified in Fig. l(a, b). 

Full plant shutdowns are necessary in bipolar cell rooms that contain only one electrolyzer. Since work must be carried out on the installed electrolyzer to change modules, electrodes, or membranes, downtime can be significant and is a function of the amount of work to be done and the design of the electrolyzer. Bipolar cell rooms with multiple electrolyzers may have one of several different configurations. Several electrolyzers may be fed in parallel from a common rectifier (common in mercurycell conversions), or individual electrolyzers may be equipped with their own rectifiers (technically, the best modem practice). Electrolyzers also may be made up of a number of packs or frames arranged in electrical series. Section 8.3.1.3 discussed some of these combinations. 

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