Bipolar electrolyzer electrical connection

In bipolar electrolyzer stacks, the face of the electrode to the left can be negative, whereas its other side, facing the next cell to the right can be positive. Naturally, these electrodes are separated and their electrical connections are provided by a metal separator plate (separation diaphragm). These units require less floor space and can operate at higher temperatures and pressures. 

Electrolyzers for the membrane cell electrolysis process are a filter press arrangement of cell units electrically arranged in two different cell configurations, mono-polar and bipolar. Figure 13 illustrates the examples of the electrical connection of the cells (65). Figure 14 illustrates the electrolysis... 

Industrial electrolyzers are made of rows of electrically connected elementary cells, preferably of the bipolar type. Many elementary ceU structures have been described in the literature. The most important from the industrial point of view are ... 

On the other hand, in bipolar cells, only the terminal cells are connected by intercell conductors, and there are typically many unit cells electrically in series between the terminal cells (Fig. 5.2). The two basic types of bipolar cells are the flat plate cell and the finger type cell. A group of bipolar cells that have a common piping system for the fluids, via manifolds, is referred to as an electrolyzer or sometimes a series or a stack. Within a single bipolar electrolyzer, there are sometimes more than one set of terminal cells. Bipolar electrolyzers can be connected via an external bus within a DC circuit in series or in parallel, but usually not both. Furthermore, in the case of mercury-cell plant conversions to membrane cells, the electrolyzers are connected electrically in parallel as shown in Fig. 5.3. 

In a bipolar arrangement the elements are connected in series with resultant low current and high voltage. The cathode of a cell is connected directly to the anode of the adjacent cell, as shown in Figure 55. The operation of a bipolar electrolyzer can be easily monitored by measurement of element voltages. If element upsets occur, a safety interlock system actuates the breakers (short-circuiting switches) and isolates the electrolyzer from the electric circuit. As the influx and efflux of electrolytes for the cells with different electric potential are gathered in common headers, problems of stray current may arise. 

A traditional, monopolar electrolyzer is built up by coupling tank units in series electrically L By contrast, a bipolar unit uses a metal sheet (or bipole ) to join adjacent cells, as depicted in Figure 4.5(b). The electrocatalyst for the negative electrode is coated on one face of the bipole and that for the positive electrode of the adjacent cell is on the reverse face. A series-connected stack of such cells forms a module that operates at a higher voltage and lower current... 

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