Technologies developed in the laboratory to destroy wastes without hazardous emissions are being applied in a pilot-scale plant under construction at the Army's Pine Bluff Arsenal in Arkansas. There, up to 80 pounds per hour of obsolete munitions, some of which date from World War II, are slurried in water to be destroyed in a supercritical water oxidation (SCWO) system. The SCWO system pressurizes and heats the slurry, which fuels an oxidation reaction. The wastes are destroyed within seconds, producing such innocuous end products as carbon dioxide, water, and salts. At the heart of the new system is a novel reactor design intended to overcome a potential complication. Treating smoke and dye munitions can create effluent of up to 35% salt. The salt is insoluble under these conditions (700C and 4,000 psi) and can plug the reactor. Sandia demonstrated a design that inhibits salt deposits by injecting pure water through small pores in an inner liner to form a protective boundary. Known as the transpiring wall reactor, this design was developed by Aerojet GenCorp for cooling and fluid management in missile and rocket applications. For more information, e-mail Nancy Garcia at firstname.lastname@example.org.
The choice between helical and spur gears in gearboxes may seem straightforward. But with planetary gearboxes, however, the choice between helical and spur gears requires some additional thought. Here’s what you need to know to make the right choice.
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