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.
-------
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.
------- |