Anode designs

In electrolytic processes, the anode is the positive terminal through which electrons pass from the electrolyte. Anode design and selection of anode materials of constmction have traditionally been the result of an optimisation of anode cost and operating economics, in addition to being dependent on the requirements of the process. Most materials used in metal anode fabrication are characteristically expensive use has, however, been justified by enhanced performance and reduced operating cost. An additional consideration that has had increasing influence on selection of the appropriate anode is concern for the environment (see Electrochemical processing). 

In flowing water enviroments a tubular rather than a solid rod cantilever anode may be used to give improved resistance to fatigue failure, since the anode design may result in fatigue failure by vortex shedding at high water velocities. 

Figure 21 shows the results from a finite-element calculation of the voltage from the cathode to various points in the anode for an anode design with an internal metal conductor as in Fig. 20. 

Figure 20. Calculated temperature distribution in a large cylindrical carbon anode design with an internal metal conductor.

Sumitomo Chemical technology consists of a number of small changes to conventional Hall-Heroult electrolysis cells, which combine to cut power consumption to some 14,000 kWh/tonne from the normal experience of 16,000 to 18,000 kWh/tonne [16]. In addition to reduced power consumption, better emission control, extended cell life, and decreased labor requirements are also achieved by these changes. Better external cell insulation, changes in what is basically a Soderberg anode design, and better fume containment by cell skirt construction modifications provide these improvements. 

All components of the photoelectron spectroscopy instrumentation have continued to evolve over the last decade. New commercial sources for XPS with the anode at high positive potential have an order of magnitude improvement in photon flux over the older grounded anode designs. Analyzers with electron lens prefocusing are far superior to unmodified hemispherical, parallel plate, or cylindrical... 

T.H. Lewis Jr., Replaceable deep anode design and installation, in Proceedings of the Corrosion and Prevention, LORESCO International, Australia, 1998, pp. 352-357. 

Zhou, Y.H., Zhang, F.L., Tvlngstedt, K., Barrau, S., Li, F.H., lian, W.L, Inganas, O., 2008. Investigation on polymer anode design for flexible polymer solar cells. Appl. Phys. Lett. 92,233308. 

In reality, the formulas give differing results. The choice of a formula is thus a matter of experience with a particular anode design. 

The standard states that the maximnm snstained current density between the anode and the concrete should not exceed 108mA/m which is correct for the anode types described but is exceeded in the manufactnrers data sheets for many probe anode designs (see Section 7.3.6) which allow far higher current densities. 

The X-ray source is generally of a twin anode design providing a broad beam source of A1 Ka hv = 1486.6eV) or Mg Ka (/tv = 1253.6 eV) X-radiation. Other sources can be used to probe deeper core levels. Possible high-energy photon sources for XPS include Si Ka (1740 eV), Zr La (2042 eV), and Ag La (2984 eV). One factor that limits the spectral resolution attainable in XPS is the natural linewidth of the X-ray source. This can be reduced substantially, and the extraneous radiation such as X-ray satellites and Bremsstrahlung removed, by the use of a crystal monochromator by which the spectral resolution is improved substantially as the X-ray linewidth is reduced from 0.85 eV to 0.35 eV, but the intensity is also reduced. 

In the 1960s, the technology of choice to produce chlorine was the mercury cell, in part because of its ability to operate at high current densities. Therefore, DS As first operated commercially in mercury cells, where rapid gas release was very important. The anode designs [107] used in mercury cells to accomplish the quick release of chlorine, so that the anode-cathode gap could be lowered and the NaCl strength in this space maintained at high levels, are shown in Fig. 4.5.18. BafBes on the back of the active anode surface are claimed [108] to provide sufficient gas lift to force the brine into the space between the anode and cathode. 

DeNora also developed a new anode design, called the Runner anode, with the THM (Titanium Hydrodynamic Means) configuration (Fig. 5.11) which utilized the gas lifting force to improve mixing of the brine, thereby eliminating the concentration gradient of brine from the bulk to the mercury interface. This allowed the operation of the cells at the... 

Galvanic Anode Cathodic Protection of Internal Submerged Surfaces of Steel Water Storage Tanks Metallurgical and Inspection Requirements for Offshore Pipeline Bracelet Anodes Design, Installation, Operation and Maintenance of Impressed Current Deep Groundbeds Internal Cathodic Protection Systems in Oil-Treating Vessels... 

These variations in ceU and anode designs also increase the chaUenge of coUecting the current from each electrode. In the case of carbon zinc ceUs shown in Fig. 1, the zinc container serves as its own current coUector. In the case of Fig. 2, a brass nail often is positimied within the center... 

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