Fig. 20.—Ground Plan of Chlorine Caustic Soda Plant,
Edgewood Arsenal.
The following description of the plant is taken from an article by S. M. Green in Chemical and Metallurgical Engineering for July 1, 1919:
“The chlorine plant building, a ground plan of which is shown in [Figure 20], consisted of a salt storage and treating building, two cell buildings, a rotary converter building, etc. In connection with the chlorine plant, there was also constructed a liquefying plant for chlorine and a sulfur chloride manufacturing and distilling plant.
“The salt storage and treating building was located on ground much below the cell buildings, which allowed the railroad to enter the brine building on the top of the salt storage tanks. These tanks were constructed of concrete. There were seven of these tanks, 34 feet long, 28 feet wide and 20 feet deep having a capacity for storing 4,000 tons of salt. There would have been 200 tons of salt used per day when the plant was running at full capacity.
“On the bottom of each tank distributing pipes for dissolving-water supply were installed, and at the top of each, at the end next to the building, there was an overflow trough and skimmer board arranged so that the dissolving-water after flowing up through the salt, overflowed into this trough and then into a piping system and into either of two collecting tanks. The system was so arranged that, if the brine was not fully saturated, it could be passed through another storage tank containing a deep body of salt. The saturated brine was pumped from the collecting tanks to any one of 24 treating tanks, each of which had a capacity of 72,000 gallons.
“The eighth storage bin was used for the storage of soda ash, used in treating the saturated brine. This was delivered from the bin on the floor level of the salt building to the soda ash dissolving tanks. From these tanks it was pumped to any one of the 24 treating tanks. After the brine was treated and settled, the clear saturated brine was drawn from the treating tanks through decanting pipes and delivered by pumps to any one of the four neutralizing tanks. These were located next to a platform on the level of the car body. This was to provide easy handling of the hydrochloric acid, which was purchased at first, though later prepared at the plant from chlorine and hydrogen. The neutralized brine was delivered from the tanks by a pump to a tank located at a height above the floor so that the brine would flow by gravity to the cells in the cell building.
“There were to be two cell buildings, each 541 feet long by 82 feet wide, and separated by partitions into four sections, containing six cell circuits of 74 cell units. Each section is a complete unit in itself, provided with separate gas pump, drying and cooling equipment, and has a guaranteed capacity of 12.5 tons of chlorine gas per 24 hours.
“Each Nelson electrolytic cell unit consists of a complete fabricated steel tank 13 by 32 by 80 inches, a perforated steel diaphragm spot welded to supporting angle irons, plate glass dome, fourteen Acheson graphite electrodes 2.5 inches in diameter, 12 inches long and fourteen pieces of graphite 4 by 4 by 17 inches, and various accessories. (The cell is completely described in Chemical and Metallurgical Engineering, August 1st, 1919.) Each cell is operated by a current of 340 amperes and 3.8 volts and is guaranteed to produce 60 pounds of chlorine gas and 65 pounds of caustic soda using not more than 120 pounds of salt per 24 hours, the gas to be at least 95 per cent pure.
