United States
                                  Environmental Protection
                                  Agency
              EPA/540/M5-91/007
              October 1991
                                 SUPERFUND INNOVATIVE
                                 TECHNOLOGY EVALUATION =
                                   Demonstration  Bulletin
                                  The Plasma Centrifugal Furnace

                                                 Retech, Inc.
Technology Description: The plasma centrifugal furnace
is a thermal technology which uses the heat generated from a
plasma torch to decontaminate metal and organic contaminated
waste. This is accomplished by melting metal-bearing solids and,
in the process, thermally destroying organic contaminants. The
molten soil forms a hard, glass-like non-leachable mass on cool-
ing. The major components of the process, shown in the figure
below, are the plasma torch, rotating reactor well,  afterburner,
secondary combustion chamber, and off-gas treatment system.
  The process operates as follows: contaminated soil is placed
in a bulk screw feeder and gradually fed into the rotating  reactor
well. Solid material is retained in the tub by centrifugal force while
a plasma arc heats the material to temperatures on the order of
3000°F. At this temperature organic contamination is volatilized
from the soil. Any combustible gases remaining after volatilization
and oxidation  are incinerated by an afterburner located down-
stream of the reactor well. At the conclusion of processing, the
feeder is stopped, the rotating well  is slowed, the afterburner is
shut off, and the molten mass of treated solids flows through the
secondary chamber and into a slag  collection chamber.
  The exhaust from the furnace  is  passed through  a gas treat-
ment system that consists of  a quench tank, a venturi scrubber, a
packed-bed scrubber and a demister. A mildly caustic solution is
supplied to the quench tank and scrubbing  unit to help remove
acidic gases  and particulates  in the off-gas.  Moisture  droplets
entrained  in the flow  are removed by the demister.  A stack
blower maintains a vacuum on the system and draws the cleaned
gases into the exhaust stack.

Waste Applicability:  This process is designed  to treat soils
and sludges  contaminated  with  heavy metals and/or organic
hazardous compounds.
       Contaminated Soil In
                                                    Plasma Torch
                                                                                            Scrubbed
                                                                                             Gas Out
                                                            Rotating Reactor Well
                                                          Secondary Combustion
                                                          Chamber
                                                                       Gas Cleanup
                Afterburne r
                 Slag
                 Collector
    Figure 1.  Simplified diagram of the Retech plasma centrifugal furnace system.

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 xvEPA
                                United States
                                Environmental Protection
                                Agency
                                                       EPA/540/M5-91/007
                                                       October  1991
                                SUPERFUND INNOVATIVE
                                TECHNOLOGY EVALUATION  =
                                  Demonstration  Bulletin
                                 The Plasma Centrifugal Furnace

                                               Retech, Inc.
Technology Description: The plasma centrifugal furnace
is a thermal technology which uses the heat generated from a
plasma torch to decontaminate metal and organic contaminated
waste. This is accomplished by melting metal-bearing solids and,
in the process, thermally destroying organic contaminants. The
molten soil forms  a hard, glass-like non-leachable mass on cool-
ing. The major components of the process, shown in the figure
below, are the plasma torch, rotating reactor well, afterburner,
secondary combustion chamber, and off-gas treatment system.
  The process  operates as follows: contaminated soil is placed
in a bulk screw feeder and  gradually fed into the rotating reactor
well. Solid material is retained in the tub by centrifugal force while
a plasma arc heats the material to temperatures on the order of
3000°F. At this temperature organic contamination is volatilized
from the soil. Any  combustible gases remaining after volatilization
and oxidation are incinerated by an afterburner located  down-
                                         stream of the reactor well. At the conclusion of processing, the
                                         feeder is stopped, the rotating well is slowed, the afterburner is
                                         shut off, and the molten mass of treated solids flows through the
                                         secondary chamber and into a slag collection chamber.
                                           The exhaust from the furnace  is passed through a gas treat-
                                         ment system that consists of a quench tank, a venturi scrubber, a
                                         packed-bed scrubber and  a demister. A mildly caustic solution is
                                         supplied to the quench tank and scrubbing  unit to help remove
                                         acidic gases and particulates  in the off-gas. Moisture droplets
                                         entrained  in the flow are removed  by the demister. A stack
                                         blower maintains a vacuum on the system and draws the cleaned
                                         gases into the exhaust stack.

                                         Waste Applicability: This process is designed to treat soils
                                         and sludges contaminated  with  heavy metals and/or organic
                                         hazardous compounds.
       Contaminated Soil In
                                                  Plasma Torch
                                                                                         Scrubbed
                                                                                          Gas Out
                                                          Rotating Reactor Well
                                                        Secondary Combustion
                                                        Chamber
                                                                     Gas Cleanup
                                                           J Heat
                                                           Exchanger
Afterburner
 Slag
 Collector
    Figure 1. Simplified diagram of the Retech plasma centrifugal furnace system.

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