Monopolar electrolyzer

Eig. 19. CME monopolar electrolyzer a, membrane b, cathode element c, half-cathode element d, current distributor e. Teflon tube f, CI2 + depleted brine manifold g, conductor rod h, CI2 + depleted brine outlet nozzle i, base frame j, recycled NaOH manifold k, recycled NaOH inlet nozzle 1, gasket (the gasket-to-element ratio is quite small) m, tie rod n, anode element o, H2 + NaOH manifold p, end plate, q, under cell bus bar (simplifies piping... 

ICIFM-21SP Monopolar Electrolyzers. Id s EM-21 SP monopolar electrolyzer incorporates stamped electrodes that are 2 mm thick and of a relatively small (0.2 m ) size (50). The electrolyte compartments are created by molded gaskets between two of the electrode plates the electrode spacing is finite and is estabHshed by gasket thickness. The electrode frames are supported from rails and are compressed between one fixed and one floating end plate by tie rods. Inlet and outlet streams are handled by internal manifolds. A crosscut view of the electrolyzer is shown in Eigure 21. As of 1989, ICI had Hcensed 20 plants having an annual capacity of 468,250 t of NaOH. 

A monopolar electrolyzer is assembled so that the anodes and cathodes are in parallel. As a result of tliis setup, the electrical potential of all cells in the electrolyzer is the same. Monopolar electrolyzers operate at a relatively low voltage, 3 to 4 V, and high amperage, allowing circuit construction of up to 200 electrolyzers. 

In the United States, 76% of the chlorine produced is from diaphragm cells. Production is equally divided between bipolar and monopolar electrolyzers. 

OxfTech Monopolar Electrolyzers. OxyTecli Systems (a joint venture company of Occidental Chemical and Eltecli Systems) supplies monopolar diaphragm electrolyzers of two designs the OxyTecli "Hooker" H-Type (27,28) shown in Figure 11 and the "Diamond" MDC-Type (28,29) in Figure 12. 

The De Nora DD-type bipolar electrolyzer is similar in construction to the monopolar electrolyzer except that each cell frame is composed of a pair... 

The details of the monopolar electrolyzer of Diamond Shamrock are shown in Figure 17. The electrolyzer is based on the monopolar design using DSA structures welded into titanium frames and the cathode structure welded into a steel frame Each cell has an active area of 1.41 m. Expected performance of this cell is shown in Figure 18 (71)(72). 

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... 

INEOS FM1 500 Electrolyzers NaCi, Hp, electricity Production of chlorine, hydrogen and 32% NaOH solution by electrolysis of NaCi solution. 91%+ efficiency, low-power consumption due to novel finite gap electrode design. Monopolar electrolyzer design 54 2009... 

FIGURE 5.26. CME monopolar electrolyzer showing bus bar alignment and internal circulation. (With permission from Chlorine Engineers Corporation.)... 

S.3.4. INEOS Electrolyzers. BMEOS FM21-SP monopolar electrolyzer (Fig. 5.29) uses stamped electrodes. The anode is a 2-mm thick titanium panel between compression-molded joints of a special cross-linked EPDM elastomer. The cathode is a 2-mm thick nickel panel between compression molded EPDM joints. 

FIGURE 5.29. INEOS FM21 -SP monopolar electrolyzer. (With permission from INEOS Chlor Ltd.)... 

The voltage drop in each monopolar electrolyzer is equal to the voltage drop of a single cell. This depends primarily on the type of cell, the current density, and the choice of membrane or type of diaphragm. The number of electrolyzers contained in a cell line then fixes its total voltage. The design voltage must be sufficient to allow for losses in buswork and interceU connectors, the maximum current density to be used, and the deterioration with time of the components of the circuit. 

Figure 11.11 and the discussion above assume the use of monopolar electrolyzers. The cost and complexity of outfitting a large plant with the instrumentation necessary for individual cell control rule out that approach. Where there are fewer electrolyzers, as in bipolar cell rooms, there are fewer control points. The use of more automation becomes practicable. Brine flow control at each electrolyzer, for example, may become automatic. The flow can be set directly by the operators or respond to electrolyzer current. Similarly, pH control can be by individual controllers on each electrolyzer. Section 7.5.6.1 discusses the merits of various approaches. Anolyte outlet pH can be controlled, typical set points being 2.3-3.0. Adaptive gain control (Section 11.2.2.4C) is useful here. 

Membrane installation details vary greatly with the type of electrolyzer. In the case of monopolar electrolyzers that can be removed from their berths for maintenance or bipolar electrolyzers containing removable single elements, membrane fitting takes place in a... 

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