Electrolyzers monopolar

Control of the flow(s) to each electrolyzer frequently is manual, with the aid of rotameters. This is especially true in monopolar installations with large numbers of electrolyzers. Monopolar diaphragm cells have essentially one chamber each for anolyte and catholyte and only one feed line (for brine). They rely on division of the feed brine... 

DeNora D88/DI75 Monopolar Electrolyzer. Monopolar electrolyzers with two different areas (0.88 and 1.75 m ) are available. The DD-type monopolar electrolyzer (Fig. 62) is a self contained unit assembled on a separate base structure and fitted with an integrated gas - liquid system. The anodic and cathodic cell frames are compressed like a filter press with rubber gaskets and a tie-rod system. The current is conducted to... 

Oy Tech MonopolarE,lectroly rs. OxyTech Systems (a joint venture company of Occidental Chemical and Eltech Systems) suppHes monopolar diaphragm electrolyzers of two designs the OxyTech "Hooker" H-Type (27,28) shown in Figure 11 and the "Diamond" MDC-Type (28,29) in Figure 12. 

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. 

The dimensionally slahle characteristic of the metal anode made the development of the membrane chlorine cell possible. These cells arc typically arranged in ail electrolyzer assembly which docs not allow for anodc-ro-cathode gap adjustment alter assembly. Also, very close tolerances are required. The latitude that titanium affords the cell designer has made a wide variety of monopolar and bipolar membrane cell designs possible. 

As a rule an electrolytic cell (electrolyzer) contains several electrodes. Depending on the kind in which the electrodes are connected to the source of the current we speak of either monopolar or bipolar electrodes. 

When it is necessary to collect the gases liberated during the electrochemical process because they are either the product required or a troublesome byproduct, the vessel is closed by a suitable cover which usually is used to support the electrodes. In the case of the filter-press electrolyzers with bipolar electrodes the top of the frames usually serves as a cover. Eleotrolyzers with monopolar electrodes are closed by covers made of steel, concrete, cement, stoneware, etc. Seals between covers and vessels or electrodes are made of asbestos cord, bitumen, asphalt, mixture of kaolin and tar, cement, synthetic resins, etc. 

The electrolytical installation consists of a series of stoneware vessels fitted with overflows the vessels are arranged in terraces so that the electrolyte flows through from one into another. The odd vessels are electrolyzers, the even ones are coolers with cooling coils of lead. Each electrolyzer is provided with a number of platinum anodes and graphite cathodes, which act as monopolar electrodes. The anodes are shaped like frames with a 0.02 mm platinum foil fixed on them. The voltage across the electrolyzer is 5.5 to 6 V usually 18 to 20 such units are... 

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. 

Fig. 24. De Nora Technologies DD-Type monopolar membrane electrolyzer.

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... 

In the monopolar system, each cell unit in one electrolyzer is connected in parallel and each electrolyzer is connected in series. Voltage across one electrolyzer is low and current passing through one electrolyzer is high. Each electrolyzer unit is connected to the next thru bolted bus bar connections which adds... 

Commercial electrolyzers have been developed using both the bipolar and monopolar cell configuration. The cell unit is generally made of metal or corrosion resistant plastics. 

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). 

The Hooker-Uhde Monopolar Membrane electrolyzer is shown in Figure 19. The active electrode surface of the HUMM electrolyzer is 1.7 m per cell element. The cell elements consist of anode frames of titanium and cathode frames of steel. Anode-cathode gap is approximately 3 mm. A separate frame is provided for holding the membrane. The electrode block rests on a support structure that serves as the header system for electrolyte and electrolysis products. Peformance of this electrolyzer is reported to be 2750 KWH/M ton NaOH at 35% caustic soda and 95% current efficiency at 3 KA/M current density (65). 

Asahi Glass Co. has developed a monopolar filter press type membrane electrolyzer that has an individual cell membrane area of 4 m. An electrolyzer may be composed of up to 32 cell units. Power consumption is reported to be 2500 KWH/M ton of NaOH at 94% current efficiency producing 35% caustic at 2 KA/M current density (73). 

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