- Look into the night sky and you will see plasma. It makes
up most visible matter in the universe, including our sun and most stars.
On Earth, it takes the form of lightning and the aurora.
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- In simple terms, plasma is a highly electrified gas.
It is formed when an intense electrical force is applied to a gas. The
force is so strong that it breaks down atoms resulting in a group of charged
particles that could no longer be called solid, liquid or gas.
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- The Army may use plasma to destroy hazardous waste at
the Anniston Army Depot with the Plasma Energy Pyrolysis System. If all
goes according to plan, the depot may have a PEPS facility within 18 months.
The system is built around a plasma arc torch, according to Vanguard Research
Inc. of Virginia, which developed the system for the Army.
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- The company has a full-scale permitted PEPS facility
in which it has destroyed a number of materials including medical waste
and ballistics, said Mel Chaskin, Vanguard's president.
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- The plasma arc torch is a "lightning rod,"
Chaskin said, that generates an electrical arc between two electrodes.
The arc charges the surrounding air, producing plasma with a temperature
of 21,000 degrees Fahrenheit. The temperature in the surrounding chamber
hovers at 3,000 degrees Fahrenheit.
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- The intense heat melts metal into glass and turns organic
material, such as plastics, rubber and petroleum products, into synthetic
gas that can then be used to produce electricity or steam.
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- The National Aeronautics and Space Administration developed
the plasma torch 40 years ago to test heat shields on spacecraft. Steel
companies have since used plasma torches in the smelting process. Four
other companies in the United States, including Westinghouse, have experimented
with plasma torches to destroy hazardous waste, but Chaskin knew of no
facilities other than Vanguard's PEPS plant in Virginia.
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- The Army says Vanguard's PEPS facility in Virginia can
destroy 10 tons per day and destroys 99.99999 percent of the material.
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- Army officials stress that the PEPS program is completely
separate from the chemical weapons incinerator at the depot; nor is pyrolysis
like incineration, because it does not involve oxygen.
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- It is all mature, off-the-shelf technology, Chaskin said.
Vanguard merely integrates the different pieces into a complete system.
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- Hazardous waste is first put in an auger feeder that
grinds the waste. It has airtight doors and negative pressure to prevent
gases from escaping, and resists jamming.
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- After the auger grinds the waste, it moves into the plasma
chamber, where the plasma arc torch destroys the material, turning inorganics
into a glass slag and organics into a synthetic gas.
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- A fan pulls out the gas, mostly hydrogen and carbon monoxide.
A gas scrubber rapidly cools the gas to prevent the formation of dioxins
and to remove any particulate. The cleaned gas can then be used to drive
a turbine. A wastewater treatment plant processes the left-over particulate
matter and water that contains carbon and trace amounts of metals.
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- In the plasma chamber, a trough collects the molten metal
and glass. It is then drained into a collection system and taken away.
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- Chaskin says a strength of his PEPS project is that it
produces a fraction of the emissions released by conventional combustion.
It can handle PCBs, pesticides, and waste paint.
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- The Anniston Army Depot currently ships those wastes
offsite for disposal. In 1999 the depot sent 8,400 pounds of hazardous
material to Vanguard's PEPS plant in Virginia and another 2,000 pounds
was transported last year. Most of that waste is paint that workers have
blasted off tanks.
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- But before the depot can get its own PEPS pilot plant
it must first receive permits from federal and state environmental agencies.
Depot officials have said they will not accept hazardous waste from elsewhere.
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- But first the Army has to perform more stringent testing,
obtain federal funding and decide whether the project is economically feasible.
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- Richard Raeke covers chemical weapons issues for The
Anniston Star. http://www.annistonstar.com/news/2001/as-calhoun-0812-rraeke-1h11v0543.htm
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