Vertical decomposers

Fig. 7. Mercury cathode electroly2er and decomposer (11) 1, brine level 2, metal anodes 3, mercury cathode, flowing along baseplate 4, mercury pump 5, vertical decomposer 6, water feed to decomposer 7, graphite packing, promoting decomposition of sodium amalgam 8, caustic Hquor exit 9, denuded mercury 10, brine feed 11, brine exit 12, hydrogen exit from decomposer 13, chlorine gas space 14, chlorine exit 15, wash water.

FIGURE 8.4 Mercury cell process for the electrolytic production of chlorine and sodium hydroxide. Packing in the vertical decomposer is graphite lumps. For treatment of cell products, see Fig. 8.2. 

FIGURE S.7. Schematic of a mercury cell with decomposer [71]. (A) Mercury cell (a) Mercury inlet box (b) Anodes (c) End box (d) Wash box. (B) Horizontal decomposer, (e) Hydrogen gas cooler (f) Graphite blades (g) Mercury pump. (C) Vertical decomposer (e) Hydrogen gas cooler (g) Mercury pump (h) Mercury distributor, (i) Packing pressing stnings CW cold water. (With permission from John Wiley Sons, Inc.)... 

Vertical decomposers, situated at the end of each cell, are provided with hydrogen coolers. The flow of the amalgam into the decomposer is by gravity. A two-compartment rubber-lined end box cleans the amalgam off the entrained brine before it enters the decomposer. 

Olin cells have a number of unique features in size, arrangement, and adjustment of anodes for voltage regulation. Olin pioneered the development of vertical decomposers, which reduce the mercury inventory required by the cells. 

The amalgam reacts with demineralized water in counterflow. Horizontal decomposers require about 30-40% of the space required for the cells. Horizontal decomposers produce caustic with a low mercury content. However, they are difficult to service and maintain. They are obsolete and have been replaced by vertical decomposers. 

Vertical decomposers are towers packed with graphite spheres or particles 8-20 mm in diameter. A typical cross section is 0.35 m per l(X)kA of cell load. The amalgam flows from the top and water is fed into the bottom of the tower. Since the volume of the decomposer is small, it is necessary to cool the hydrogen generated during the course of the amalgam decomposition reaction. The mercury inventory is small with the vertical decomposer. However, the caustic contains more mercury. 

C) Vertical decomposer e) Hydrogen gas cooler g) Mercury pump h) Mercury distributor I) Packing pressing springs... 

The bus bars in the Solvay cells are made primarily of aluminum. Above the cells is a cover that also serves as a convenient walkway, giving access to the anode rods. The titanium anodes are specially coated and are automatically adjusted by computer. The tall vertical decomposers are located under the cells. 

Figure 29. Processing of sodium hydroxide solution from the amalgam decomposer a) Vertical decomposer, b) Collection main c) Collecting tank d) Pump e) Cooler f) Mercury removal filter...

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