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OCR for page 71
5
Burns and Roe Technology Package
INTRODUCTION AND OVERVIEW
The Burns and Roe team's technology package is
shown schematically in Figure 5-1. This package uti-
lizes the Army's baseline disassembly technology to
separate the components of munitions (e.g., chemical
agent, fuzes, bursters, metal casings, etc.), with subse-
quent treatment by high-temperature plasma to decom-
pose the chemical agents, propellants, and wooden, fi-
berglass, or plastic packing materials. All metals,
including the munition casings, are melted by the
plasma. An explosion chamber is used to deactivate
explosive components by energetic initiation (detona-
tion or deflagration). Debris and gas from the explo-
sion chamber are then also treated using high-tempera-
ture plasma. The technology provider's approach for
performing the required major demilitarization opera-
tions is summarized in Table 5-1.
Because plasma waste treatment, which is integral
to the proposed system, is a unique technology, plas-
mas and their characteristics are discussed first. The
Burns and Roe technology package is then described in
detail.
Background on Plasma
Electric arcs and discharges have been of interest to
scientists and engineers for decades because they in-
volve high-temperature, conductive gases (plasmas).
Typically, an arc can be established between two con-
ducting electrodes (e.g., graphite or metal) in a variety
of atmospheres. The plasma is comprised of molecules,
atoms, ions, and electrons at temperatures of 1,000°C
71
to 20,000°C (1,832°F to 36,032°F) depending on the
current and voltage, the gaseous environment, and the
pressure of the constricting gas. Either physical or mag-
netic constriction can be used to increase temperatures.
Because plasma arcs between electrodes generally
involve voltage drops of 100 V or more, chemical
bonds (whose strengths range from 2 to 10 electron
volts LeV]) will be broken, and ionization processes (at
4 eV to 25 eV) will occur. Thus, material exposed to a
plasma environment will be transformed into atoms,
ions, and electrons, with only a few molecules remain-
ing. This makes the potential use of plasma arcs,
torches, melters, and other plasma devices attractive
for destroying undesirable molecules (e.g., hazardous
wastes). High-temperature plasmas can also produce
endothermic neutral species (e.g., C2H2, C2N2, and NO)
or gaseous molecular ions (e.g., SiO+ and CO+. When
the plasma is cooled to room temperature, most of the
molecules are thermodynamically stable, but some
metastable species (that are stable at higher tempera-
tures but unstable at lower temperatures) might sur-
vive. In addition, metastable species could be formed
during cooling, which could also be present at room
temperature.
DESCRIPTION OF THE TECHNOLOGY PACKAGE
Disassembly of Munitions and the Removal
of Agent/Energetics
The technology provider proposes using the baseline
approach to disassemble munitions and segregate the
agent, energetic materials, and munition bodies. (See
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72
Munitions | Baseline ~Agent
~ disassembly
-
Munition
unpack
'1
Fuzes and
bursters
Energetic
destruction
chamber
Rocket motors
Dunnage
Metal parts
Plasma waste
converters
C1 and C2
· Plasma waste
converter
· B
Residue from
fuzes and
bursters
Plasma waste
converter
D
FIGURE 5-1 Schematic diagram of the Burns and Roe technology package.
Appendix C for a description of the baseline disassem-
bly system.) The only modifications to the baseline dis-
assembly process, which occur subsequent to removal
of agent and energetics, are: (1) limiting the number of
munition bodies per tray to nine, and (2) modifying the
conveyors to accept smaller trays.
Description of the Plasma Waste Converter
The Burns and Roe technology package uses spe-
cialized plasma waste converters (PWCs) to treat all
materials, including chemical agent. Six PWCs of four
different types are proposed: two to treat agent and
munition bodies (PWC A1 and PWC A2), one to treat
pieces of rocket motors containing propellant (PWC B),
two to treat metal parts to the 5X standard (PWC C1
ALTERNATIVE TECHNOLOGIES FOR DEMILITARIZATION OF ASSEMBLED CHEMICAL WEAPONS
Plasma waste Pollution
converters · abatement system
A1 and A2 A
Brine to treatment
Pollution
· abatement system
Brine to treatment
· 5X metals to off-site facility
Pollution
abatement system
B
Brine to treatment
_ 5X metals to off-site facility
Pollution
· abatement system ·
Brine to treatment
Gas to hold-test-release
system (may be burned
in boiler)
and PWC C2), and one to treat dunnage (PWC D). The
basic operation of all the PWCs is the same.
A typical PWC (Figure 5-2) is a cylindrical, refrac
tory-lined vessel with an opening in the roof through
which a plasma torch is inserted. (For larger PWCs,
more than one torch may be used through more than
one opening.) There are no airtight seals between the
plasma torch and the vessel roof, and the PWC is oper-
ated at slightly negative pressure to prevent gas from
exiting through the opening. Thus, air is always leak-
ing into the PWC. Each plasma torch is a non-
transferred torch1 consisting of a cylindrical pipe con-
taining water-cooled copper electrodes. The plasma
IIn a nontransferred torch, both the anode and cathode are contained
within the torch.
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BURNS AND ROE TECHNOLOGY PACKAGE
TABLE 5-1 Summary of the Burns and Roe Approach
Major Demilitarization Operation Approach(es)
Disassembly of munitions Army baseline disassembly process.
Treatment of chemical agent Thermal destruction using plasma waste converter (PWC).
Treatment of energetics Initiation of explosives in explosion chamber (residual passed through PWC); destruction of propellant
in PWC.
Treatment of metal parts SX treatment of metals (complete melting) in PWC.
Treatment of dunnage SX treatment of dunnage in PWC.
Disposal of waste Solids. Slag for recycling; salts from scrubbers to appropriately permitted landfill.
Liquids. None.
Gases. Hold and test; feed to boiler or thermal oxidizer (combustion) if test results are acceptable.
feed gas passes through the torch, and the plasma is
formed in the torch between the anode and cathode. No
other materials, such as agent or energetics, are intro-
duced into the plasma torch.
The torch creates a plasma with a temperature, as
reported by the technology provider, in the range of
15,000°C (27,032°F).2 The plasma exits the torch into
the PWC chamber and impacts onto solid and liquid
material (e.g., metal from weapons) at the bottom of
the chamber. In an agent-treatment PWC, agent is in-
troduced into the hot plasma near the bottom of the
PWC chamber. Steam is introduced with the agent at a
controlled rate to convert elemental carbon or soot (cre-
ated by dissociation of the feed stream molecules) to
CO.
The plasma exiting the torch cools very quickly
in the chamber by a combination of the following
mechanisms:
· mixing with infiltration air
· sensible heat required to heat the waste feed to the
PWC
· the endothermic chemistry of degradation of the
agent and other organic waste materials introduced
into the PWC
· decomposition of the steam introduced for soot
control
· decomposition of the CO2, if used as a plasma feed
gas
2Because plasmas can contain molecules, atoms, ions, arid free electrons,
several plasma temperatures can be defined. The committee considers the
temperature listed here to be reasonably representative of the very high
temperatures of the plasma components.
73
· formation of NOX from nitrogen in the weapons
material feed, the plasma feed gas (if N2), or infil-
tration air
· heat losses through the PWC shell
For the demonstration system, the technology pro-
vider indicates that the air in-leakage rate is approxi-
mately 30 standard cubic feet per minute (SCFM)
(Burns and Roe, 1999), compared to a plasma feed gas
flow rate of approximately 20 SCFM and a PWC total
gas outflow on the order of 140 SCFM (Burns and Roe,
1998b). The temperature of the exit gas for the PWC is
Air infiltration \, 1
Mixed bulk
gases
Rae
Chemical
agent and
steam
Plasma feed gas ~1,100°C product gas
(Ar, CO2, or N2) (to pollution abatement
Plasma
torch
I // I\ Plasma at
~L:~
Molten slap pool (if present)
FIGURE 5-2 Schematic diagram of a typical plasma waste
converter (PWC) for treating agent.
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74
ALTERNATIVE TECHNOLOGIES FOR DEMILITARIZATION OF ASSEMBLED CHEMICAL WEAPONS
estimated to be approximately 1 ,1 00°C (2,01 2°F)
(Burns and Roe, 1997~.
Treatment of Chemical Agent
After being drained from the munitions, chemical
agent is pumped to storage tanks and, subsequently,
into one of two PWCs designated Al or A2, identical
units approximately 7 It in diameter and 9 It high (ex-
ternal dimensions) designed for liquid feed of up to
1,200 lb/hr. Agent and steam are injected into the PWC
where they mix with the hot plasma. Product gas then
passes through a pollution abatement system (PAS)
consisting of four major components:
· a vertical down-flow duct with water/caustic spray
to quench the gas
· a countercurrent, multistage acid-gas scrubber
with vertical upward gas flow and gravity-driven,
.
downward flow of scrubbing liquid
· a mist eliminator
a cartridge filter for the removal of fine
particulates
Upon exiting the PAS, the product gas enters a hold-
test-release system consisting of a compressor, a con-
denser, and storage tanks. The tank contents are
sampled for chemical agent and other components (not
yet specified). If no agent is detected, the technology
provider plans either to (1) burn the gas in an on-site
boiler or oxidizer or (2) sell it as a fuel. If agent is
detected, the gas is recycled to PWC Al or A2 for
reprocessing.
Treatment of Energetics
Two general types of energetic materials will be
treated: M55 rocket propellant (designated M28),
which is configured to burn rather than detonate; and
burster and fuze materials, which are intended to deto-
nate upon initiation.
MSS Rocket Propellant
After being sheared, the severed M55 rocket motor
pieces containing the M28 propellant are fed into PWC
B 7 It in diameter and approximately 9 It high (exter-
nal dimensions) designed to destroy energetic
materials at rates of up to 1,500 lb/hr. The unit is fabri-
cated of 2.5-inch-thick carbon steel to contain any ac-
cidental explosions. PWC B also includes a feed chute
and hydraulic ram for introducing the waste material
into the vessel.
The waste materials mix with the hot plasma, and
product gas is discharged to the same PAS and hold-
test-release system described previously. Some rocket-
component materials (e.g., metal parts and fiberglass
shipping and firing-tube pieces) do not remain in the
plasma field long enough to vaporize but melt, forming
a molten pool at the bottom of the vessel. The metals
are tapped and drained to form ingots. Nonmetallic slag
is also periodically tapped and drained.
Other Energetics
To lower the risk of detonations in the PWC, the
technology provider proposes deactivating explosive
material in an explosion chamber. This chamber is
commercially available (designed and manufactured by
Bofors) and is used by both the military and industry to
deactivate small quantities of explosives. It is made of
thick high-strength steel and is designed (1) to with-
stand multiple detonations of a specific mass of TNT,
and (2) to contain the product gas from the detonations.
Both the quantity and type of energetic material treated
per batch must be known in advance to ensure that the
unit's explosive rating is not exceeded.
In this application, the bursters and fuzes from rock-
ets, projectiles, mortars, and land mines are fed into the
explosion chamber, where they are thermally initiated.
The gas from the explosion chamber is then slowly
vented to PWC B for further treatment. The solids are
removed and are also fed to PWC B. The gaseous and
molten products from PWC B are treated in the same
way as the M55 rocket products discussed in the pre-
ceding section.
Treatment of Metal Parts
Bodies of projectiles and land mines, drained of
agent and emptied of energetic materials, are placed in
trays and conveyed to PWC C1 or C2 identical PWCs
designed to decontaminate and melt metal parts. The
proposed units are 7 It in diameter and 9 It high (exter-
nal dimensions), with a peak capacity of 6,000 lb/hr of
OCR for page 75
BURNS AND ROE TECHNOLOGY PACKAGE
metal munition bodies. Trays of munition bodies are
moved by roller conveyor to a scissor lift that raises the
trays to a feed chute. The tray is conveyed into the feed
chute, and a ram pushes the tray containing the muni-
tion bodies into the PWC where both are consumed.
Gaseous products flow through the PAS and hold-test-
release system described previously. Molten metal col-
lects in the bottom of the PWC, which is tapped peri-
odically and the metal cast into ingots. This metal will
be considered as treated to 5X condition because it will
meet the criterion of "heated to at least 1,000°F for at
least 15 minutes."
Treatment of Dunnage
Dunnage is gravity-fed to a shredder for size reduc-
tion and fed to PWC D (approximately 5 It in diameter
and 5 It high [external dimensions]) designed to de-
stroy dunnage at rates of up to 1,200 lb/hr. Gaseous
products flow though the PAS and hold-test-release
system described previously. Molten materials col-
lected in the bottom of the PWC are periodically recov-
ered. The technology provider proposes to control the
formation of graphite, soot, and other carbonaceous
material by adding steam to form CO.
Process Instrumentation, Monitoring,
and Control
Monitoring of "traditional" process variables (e.g.,
temperatures, liquid and gas flow rates, etc.) is accom-
plished using standard, off-the-shelf, chemical-process
equipment and instrumentation. Monitoring for agent
is accomplished using the ACAMS and depot area air
monitoring system (DAAMS) developed by the Army.
Agent feed to the PWC is monitored for flow rate
and pressure, with real-time signals relayed to the con-
trol room. Automatic feed cutoff valves are employed
if operational ranges (yet to be established) are vio-
lated. Sensors in the energetic feed chute and the muni-
tion metal-body conveyor detect blockage of feed ma-
terial and initiate appropriate action, which could
include PWC shutdown. (Because the feeds are not
critical to PWC operation, automatic shutdown because
of a feed blockage is not included.)
Inside the PWCs, power feed, plasma feed gas flow,
vessel pressure and temperature, and steam flow are
75
monitored and controlled to within established operat-
ing ranges. Appropriate pressure, temperature, and
flow-sensing instrumentation is used to gather and
transmit the information to the control room. Any de-
viation from the established limits of any of the param-
eters cited above results in automatic PWC shutdown.
The product gas leaving the PWC is cooled, com-
pressed, and collected in tanks downstream of the PAS.
This gas is then sampled and analyzed for chemical
agent using both ACAMS and DAAMS agent monitors.
Feed Streams
In addition to the munitions and packing materials,
the following materials are fed to the system:
· the plasma feed gas, which acts as the plasma me-
dium to the PWCs (argon was specified in the
technology provider's proposal; N2 and CO2 are
being used in the demonstration unit)
· steam to the PWCs to convert elemental carbon to
CO
· caustic to the PAS to support the quenching and
scrubbing operations
~ make-up water to the PAS to support the quench-
ing and scrubbing operations
The technology provider has generated a mass balance
for the proposed system using the maximum possible
feed rates to each PWC. This results in a "mix-and-
match" configuration that is not representative of any
particular munition campaign. Nevertheless, the infor-
mation reflects the sizes of anticipated flows. Process
inputs are summarized in Table 5-2.
Waste Streams
The waste streams from the system will be either
gaseous or solid. There is no liquid waste stream. (Wet
scrubbers are used to absorb and neutralize products
like HC1, HE, SO2, and P4O~o using a caustic solution,
but the scrubber liquid is subsequently evaporated,
leaving a salt cake.)
Gases
The product gas from the PWCs is quenched in a
vertical down-flow duct with water/caustic spray. It
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76
ALTERNATIVE TECHNOLOGIES FOR DEMILITARIZATION OF ASSEMBLED CHEMICAL WEAPONS
TABLE 5-2 System Inputs for the Burns and Roe So/ids
Mass Balance
Scrubber Brine Wastes. The brine from the PAS
StreamFlow (lb/hr) scrubber is processed to recover salts using the baseline
brine reduction system. This system dries the brine with
Inputs to PWCs Al and A2a
HD1,170 rotary-drum dryers to yield low water-content salts (5
Decontamination solution, oil, laboratory waste650 to 15 percent by weight). The water vapor is discharged
Steami78 to the atmosphere; the water is not recycled. The salts
are sent to an appropriately permitted landfill for dis
Inputs to PWC Bb
M28 propellant386 posal. (Consideration is also being given to recycling
Decontamination solution25 the brine through a PWC.)
Comp B464
Fiberglass200 Metal Munition Bodies. The 5X-treated molten
Metal parts270
Steam46 metal is drained from the PWCs, cast into ingots, and
Argon400 sold for scrap.
Inputs to PWCs C1 and C2a
HD585 Residues from the PWC Bottoms. Nonmetallic ma
Metal parts8,600 serials that collect in the bottom of the PWCs are mixed
stegaOm26s with sand in the unit and recovered as a vitrified mate
rial (slag).
Input to PWC D
Miscellaneous dunnage1,165 The process outputs from the technology provider's
Steam450 mass balance are summarized in Table 5-3. The pre
Argon200 dieted compositions of the gaseous effluent streams
Input to pollution abatement systemsfrom the PWCs are shown in Table 5-4 and the pre
Make-up water7,997 '
Caustic (30 percent NaOH)5,867 dieted compositions after scrubbing are shown in Table
5-5. (The compositions would be different if a plasma
Total mass input to system30,118
aloe HD-filled 155-mm projectiles per hr
b20 M55 rockets per hr
Source: Burns and Roe, 1998a.
TABLE 5-3 Mass Outputs for the Burns and Roe
System
StreamFlow (lb/hr)
then passes through a packed tower for acid-gas scrub
bing (using caustic) and a mist eliminator for water Outputs from PAS for PWCs Al and A2a
removal. Fine particulates are removed by a cartridge product gasi,822
filter. (A venturi scrubber is included in the demonstra- Outputs from PAS for PWC Bb
lion system for particulate removal, just prior to the product gasi,036
packed tower [Burns and Roe, 1998b].) Brine83
Following treatment with the pollution control
Outputs from PAS for PWCs C! and C2a
equipment Just described, the product gas Is held In a product gasi,214
pressure vessel where it is sampled and analyzed for Brine4,864
agent and other components (still to be determined). If Outputs from PAS for PWC Dc
the gas is agent-contaminated, it is recycled to the PWCs product gas539
for further treatment. If no agent is detected, (1) the gas
Metals/silicates/bottom materials from PWCs9,236
Is used as fuel for an on-s~te boiler, (2) the gas Is
shipped off site as fuel for other applications, or (3) the Total mass output from system30,166
gas is burned in an on-site oxidizer. If the gas is burned a
100 HD-f~lled 155-mm progechles per hr
in a boiler or oxidizer, gaseous effluents from the boiler b20 M55 rockets per hr
or thermal oxidizer are scrubbed and released to the Cmiscellaneous dunnage waste
environment via a traditional stack. Source: Burns and Roe, 199Sa.
OCR for page 77
BURNS AND ROE TECHNOLOGY PACKAGE
TABLE 5-4 Predicted Composition of Product Gas
from the Plasma Waste Converters (Prior to Scrubbings
TABLE 5-5 Predicted Composition of Product Gas
from the Plasma Waste Converters after Scrubbinga
PWC PWC PWC PWC PWC PWC PWC PWC
Compound A1 end A2b BC C1 and C2b Dd Compound A1 end A2b BC C1 and C2b Dd
77
COS 22.08 9.57 COS 22.08 9.57
CO 706.01 385.43286.61 783.42 CO 706.01 385.43286.61 783.42
C2H2 89.98 36.56 C2H2 89.98 36.56
H2CO 19.65 7 99 H2CO 15.72 6.39
CH417.39 7.827.0715.89 CH417.39 7.827.0715.89
H2O95.41 36.5544.068.22 H2O5.28 2.672.725.23
H290.79 29.6134.40102.64 H290.79 29.6134.40102.64
Ar800.00 400.00800.00200.00 Ar800.00 400.00800.00200.00
Total2,797.68 1,080.901,650.011,449.46 Total1,822.18 1,035.841,214.111,400.05
aPlasma feed gas is argon; temperature is approximately 1,100°C
(2012°F); all quantities in lb/hr.
bloo HD-filled 155-mm projectiles per hr
C20 M55 rockets per hr
dmiscellaneous dunnage waste
Source: Burns and Roe, 1998a.
feed gas other than argon were used; CO2 and N2 are
being tested in the demonstrations.)
Start-up and Shutdown
PWC start-up procedures involve first initiating the
plasma feed gas flow, the torch cooling-water flow, and
the plasma-torch power. The vessel is then allowed to
reach the prescribed operating temperature, which usu-
ally takes approximately two hours from a "cold" start-
up. Weapons material feed and steam flow (to convert
elemental carbon to CO) are then initiated. The tech-
nology provider estimates that once the vessel reaches
the desired temperature, steady operation at capacity
can be achieved in approximately five minutes.
Upon shutdown, the weapons material feed is
stopped, the steam flow is cut off, the power to the
torch is turned off, and the plasma feed gas flow is
stopped. The torch cooling water continues for approxi-
mately 30 minutes to protect the electrodes during cool
down of the vessel.
aall quantities in lb/hr
bloo HD-filled 155-mm projectiles per hr
C20 M55 rockets per hr
dmiscellaneous dunnage waste
Source: Burns and Roe, 1998a.
EVALUATION OF TH E TECH NOLOGY PACKAG E
Process Efficacy
Effectiveness
Because assembled chemical weapons contain
mainly the elements C, O. H. N. S. P. halogens, and
various metals (e.g., A1, Fe, Co, Ni), one can predict
from standard thermodynamic calculations that CO,
H2, CO2, H2O, H2S, HC1, HF, N2, NOX, SOx, and vari-
ous metal oxides will be formed at ambient tempera-
tures (e.g., 20°C to 35°C; 68°F to 95°F), depending on
the availability of oxygen. Compositions at higher
temperatures can also be calculated, and Tables 5-6 and
5-7 show the mole fractions of the equilibrium prod-
ucts at 2,227°C (4,040°F) for various agent and ener-
getic feed materials predicted by the technology pro-
vider, assuming argon is the plasma feed gas (Burns
and Roe, 1997~. These results were not generated via
testing but were calculated by a chemical-equilibrium
computer program (IVTANTHERMO) that uses stan-
dard thermodynamic data (Burns and Roe, 1997). Most
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78
ALTERNATIVE TECHNOLOGIES FOR DEMILITARIZATION OF ASSEMBLED CHEMICAL WEAPONS
TABLE 5-6 Theoretical Equilibrium Composition of
Product Gas from Plasma Treatment of Agentsa
Mole Fraction
Species Produced GB Feed VX Feed
TABLE 5-7 Theoretical Equilibrium Composition of
Product Gas from Plasma Treatment of Energeticsa
Mole Fraction
HD Feed Species Produced
TNT Feed Tetryl Feed NC Feed
HE
PO
N2
SH
S.Ox 10-2
3.9x 10-2
l.Sx 10-2
1.1 x 10-2
6.8 x 10-3
N2
SH
H
1.2x 10-2
3.2 x 10-3
2.2x 10-2
3.1 x 10-3
3.3 x 10-3
1.8 x 10-2
1.3 x 10-3
3.1 x 10-2
S
SO
P2
PO2
4.4 x 10-3
1.3 x 10-3
2.5x 10-3
1.7 x 10-3
1.2 x 10-3
PN
PH2
P2O3
1.3 x 10-4
6.5x 10-5
4.1 x 10-5 2.9 x 10-5
3.6x 10-5
C2H2
COOH
H2CO
C1
C2H
CH4
CH3
2.1 x 10-2
9.3 x 10-3
6.1 x 10-3
3.6 x 10-3
9.1 x 10-5
3.5x 10-5
2.9x 10-5
2.5x 10-5
aPlasma feed-gas is argon; temperature is 2,230°C (4,040°F).
Source: Burns and Roe, 1997.
of the higher temperature species should revert to CO2,
H2O, CO, and H2 when cooled. However, the product
distribution and composition might be partially kineti-
cally controlled rather than thermodynamically deter-
mined. Thus, species that are stable at higher tempera-
tures but metastable at lower temperatures might be
present after cooling.
C3H
C2H
HCN
CN
9.0X 10-5
1.6x 10-5
4.0x 10-3
3.9x 10-5
a~l r 1 · · O O
5.5 X 10-2 rlaSma reea-gas 1S argon; temperature 1S 2,230 C (4,040 F).
Source: Burns and Roe, 1997.
The plasma temperature in the PWCs is estimated
by the technology provider to be in the range of
15,000°C (27,032°F). Although one would expect very
high destruction efficiencies at this temperature, much
of the agent may not be exposed to such a high tem
perature in the PWCs. The plasma arc is created in an
enclosed torch through which only the plasma feed gas
(e.g., argon, N2, or CO2) flows. The arc heats the gas,
which ionizes, dissociates, and then flows into the
chamber surrounding the torch. The chemical agent is
injected into the side of the chamber, not through the
torch (see Figure 5-2). Inside the chamber, the agent
mixes with the plasma. The maximum temperature to
which each agent molecule is exposed is unknown, but
the temperature gradient within the chamber is very
large, as is evidenced by the estimated gas exit tem
perature of 1,100°C (2,012°F) (Burns and Roe, 1997 ).
The heterogeneous conditions in the PWC could
cause organic intermediates to form. The prevailing
view is that organic intermediates3 are formed during
an initial vaporization and pyrolysis phase, prior to
3In combustion systems, these organic intermediates are usually referred
to as products of incomplete combustion (PICs). Typical examples include
benzene, toluene, and naphthalene.
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BURNS AND ROE TECHNOLOGY PACKAGE
oxidation (Dellinger et al., 1986; Glassman, 1987;
Dempsey and Oppelt, 1993~. If complete mixing of the
intermediates and stoichiometric quantities of oxidant
occurs, all of the intermediates would be oxidized.
However, in practice, the mixing will not be perfect,
and some intermediates may bypass the plasma zone
without being complete oxidized, even if sufficient
oxidant is present. In addition, larger particles may not
have sufficient time to decompose completely in the
plasma zone. This imperfect mixing might also allow a
small fraction of the original fuel or waste to pass down-
stream intact, without being pyrolyzed or oxidized.
The oxidant in the PWCs may come from the plasma
feed gas (if air or CO2 is used), or it may come from air
in-leakage into the PWC from the surrounding room.
For the demonstration system, the technology provider
has indicated that the air in-leakage rate is approximately
30 SCFM (Burns and Roe, 1999), compared to a plasma
feed gas flow rate of approximately 20 SCFM and a PWC
total gas outflow on the order of 140 SCFM (Burns and
Roe, 1998b). Thus, the air in-leakage forms a significant
fraction of the total gas flow for the demonstration unit. If
the available oxygen is less than the amount theoretically
required for the complete oxidation of organics (includ-
ing organic intermediates), then the lack of oxygen,
coupled with incomplete mixing, could lead to signifi-
cant quantities of organic intermediates being formed
and passed downstream from the PWCs to the PAS.
For the reasons described above, the committee
doubts that all of the chemical agent feed would actu-
ally be exposed to the ultra-high temperature plasma
and believes that some residual toxic materials would
remain or form. Nonhomogeneous temperature distri-
butions, gas turbulence, and incomplete mixing may
limit the absolute effectiveness of this process (i.e., the
target destruction efficiencies would not be achievable
at the required throughput rates). Actual chemical
agents and munition components must be processed in
the proposed PWCs (or other units of similar size and
design) to prove the efficacy of the process and to opti-
mize design parameters, such as flow rates, reduction/
oxidation conditions, and residence times. Design pa-
rameters will be very sensitive to equipment configu-
ration, scale-up, plasma feed gas, and the type of
chemical weapon and feed rate. The results of the dem-
onstration tests, which are being performed at a reduced
scale, could provide some (but not all) of the data to
address these concerns.
79
The technology provider supplied a comparison be-
tween the theoretical products and the products mea-
sured by GC (gas chromato~ranhv) for a mixed feed of
. . . .. .
", ~ ,,
polyethylene, cellulose, water, and air to a PWC of
unspecified size (Burns and Roe, 1997~. This is shown
in Table 5-8. The technology provider states that "due
to the limitations of gas chromatography, the samples
were analyzed only for the primary components of the
[product gas]." Thus, approximately 6 percent of the
gas was not accounted for by the GC analysis, and there
are discrepancies between the theoretical and measured
concentrations. Regarding these discrepancies, the
technology provider observed that "the computer tends
to underestimate hydrocarbon species and oxygen,
while overestimating carbon monoxide and hydrogen"
(Burns and Roe, 1997~. This statement reinforces the
committee's concern that hydrocarbon species not pre-
dicted by equilibrium calculations (including trace or-
ganic species that are of environmental concern) could
be present in the product gas from the PWC.
The technology provider has indicated that soot for-
mation in the PWC could be significant. This phenom-
enon is predicted by the thermodynamics. If CO2 is
TABLE 5-8 Comparison of Experimental and Predicted
Gas Compositions Subsequent to Plasma Treatmenta
Mole Fractions
From Gas
Chromatography
Predicted by
Equilibrium Calculations
CH4
co2
C2H2
C2H4
NH3
N
C
Other
Total
3.12
3.87
0.61
Coo
2.12
Coo
Coo
na
na
na
na
93.8s
l.Ox 10-6
1.0x 10-7
2.0 x 10-12
0.8s
00.00
aPlasma feed-gas is air; waste/air feed is approximated by
C2sHlo4o44Nl7
bThe technology provider did not analyze for these compounds.
Source: Burns and Roe, 1997.
OCR for page 80
80
ALTERNATIVE TECHNOLOGIES FOR DEMILITARIZATION OF ASSEMBLED CHEMICAL WEAPONS
used as the plasma feed gas, it is also possible for soot
to form if the resulting CO disproportionates to C(gr) +
CO2. The technology provider has proposed adding
steam to the feed to convert elemental carbon to CO.
This approach has been demonstrated in various plasma
systems used for processing municipal waste. How-
ever, careful control of the steam-to-carbon ratio would
be required to control the formation of soot. Otherwise,
there could be significant emissions of soot. In prac-
tice, this control could be difficult to achieve with waste
streams of various compositions.
The committee was informed by the technology pro-
vider that argon was not used for the demonstrations
because it was too expensive (Burns and Roe, 1999~.
Burns and Roe had planned to use air as the plasma
feed gas until it was suggested that members of the
Dialogue might consider the use of air to be akin to
incineration (Hindman et al., 1999~. The technology
provider then tested CO2 as the plasma feed gas but
ultimately decided to use N2. Because different plasma
feed gases have different thermodynamic and chemical
properties, the choice of the plasma feed gas can have a
significant impact on the performance of the system.
For example, the power requirements will vary with
the plasma feed gas. Electrode wear may also depend
on the type of gas, and the composition of the product
gas will certainly vary. Therefore, tests performed with
one plasma feed gas may not be indicative of perfor-
mance with a different gas.
The volatile low molecular weight chlorinated hy-
drocarbons in mustard that can be difficult to destroy
are not expected to pose a special difficulty for the
plasma treatment units, although this has yet to be
demonstrated.
Sampling and Analysis
From the responses to the data-gap questions (Burns
and Roe, 1998a), it appears that the technology pro-
vider expects to use the same sampling and analytical
procedures being used in the baseline incineration sys-
tem. These are probably adequate.
Maturity
Research on plasma-arc technology dates back to the
early 1900s, and many practical industrial applications
have been developed, including arc melting of metals;
electric arc welding; plasma processing of ores; plasma
spraying of metallic or oxide powders; and plasma gen-
eration of atomic, ionic, and molecular spectra for ana-
lytical systems. Plasma arcs have also been used for
treating hazardous wastes. According to the General
Accounting Office (GAO), research plasma-arc furnaces
have ranged from 2 to 8 It in diameter, with power
levels of 150 kW to more than 1 MW (GAO, 1999~.
Wastes treated include solvents, paint, batteries, incin-
erator ash, and radioactive materials. Of the research
initiatives by the U.S. Department of Energy and
DOD over the past 10 years on plasma treatment of
hazardous waste, two have reached the implementa-
tion stage: (1) a Navy project to destroy hazardous
materials on shore (scheduled for operation in 2000),
and (2) an ongoing asbestos destruction project at Port
Clinton, Ohio. Other projects are still in the research
phase. Although organic wastes have been destroyed
using plasma-arc furnaces, much of the research to date
has focused on the vitrification of inorganic substances
within wastes (e.g., radioisotopes) rather than on the
destruction of organic wastes.
A subgroup of the committee visited an Ontario
Hydro Technologies site (Toronto, Ontario) on April 5,
1998, to observe a prototype PWC and to be updated
on progress in the development of equipment for use
with real chemical agents and energetics during the
ACWA demonstration phase (see Appendix B). The
visiting team was shown a basic version of the technol-
ogy provider's PWC system. The items observed in-
cluded (1) a long pipe with water-cooled copper elec-
trodes that operated as a nontransferred DC-plasma
torch emitting hot plasma, and (2) a cylindrical furnace
system about 6 It tall and 3 to 4 It in diameter (external
dimensions) with an opening on the top for batch feed-
ing. The electric power requirements (DC) for this unit
were on the order of 100 kW to 500 kW, depending
on the type of waste and processing rates (e.g., 100 to
500 lb/hr).
During the subcommittee's visit, the small DC-
plasma torch that fed the plasma into a refractory-lined
furnace was used to demonstrate the treatment of the
following materials:
· a simulated, double-base Propellant (nitro~lvcerin
and nitrocellulose)
1 1 ~7 ~
OCR for page 81
BURNS AND ROE TECHNOLOGY PACKAGE
· metals
· plastics
· household materials
All of these materials, which were hand loaded by
members of the visiting team, were melted or decom-
posed in the plasma discharge, as viewed on a TV
monitor. No spectroscopic monitoring devices-
optical or mass spectrometric were in operation. A
ram feeder and a refractory trough on the device were
apparently intended for removing slag. The proposed
units for scrubbing SOx and HC1 and for extracting
desired products (e.g., CO, H2, and metals or silicate
products), which are shown schematically in the sys-
tem diagrams, were not present at the Ontario Hydro
site. The demonstration system being tested at Edge-
wood, Maryland, is designed to perform these func-
tions (Burns and Roe, 1998b).
The PWCs proposed by the technology provider
have never been tested with actual munitions or chemi-
cal agents. According to Burns and Roe (1997), tests
conducted by Acurex Environmental Corporation at the
EPA's Air Pollution Prevention and Control Division
of the National Risk Management Research Labora-
tory showed that a PWC could destroy simulants of
nerve agents, blister agents, and energetics. The PWC
tested was a refractory-lined stainless steel vessel sized
to process 25 lb/hr of material. It was equipped with a
50 kW to 100 kW, nontransferred, water-cooled DC
torch, and the plasma feed gas was argon. The total
amount of material destroyed was not reported. In all
cases, the destruction efficiencies were stated to be in
excess of 99.9999 percent.
Work by MSE, Inc., of Butte, Montana, in 1993 un-
der Department of Energy sponsorship and using a
plasma centrifugal furnace made by RETECH, Inc.,
was cited to validate the effective use of a plasma fur-
nace for the destruction of MK 72 Mod 5 fuzes. A
Startech report on PWC processing of pyrotechnic-con-
taminated materials for Ensign-Bickford in October
1995 gave no details about the PWC used or about the
quantities of material processed (Burns and Roe,
1998a). Major products were identified by GC. A unit
developed at Drexel University used an inductively-
coupled argon-based plasma device to process energet-
ics and agent simulants (Burns and Roe, 1997~.
The full-scale units proposed by the technology
81
provider have not been produced yet. A smaller proto-
type, larger than the units at Ontario Hydro, is being
tested between February and May of 1999 at an Army
test facility in Edgewood, Maryland.
Robustness
Based on the many practical applications of plasma
technology in the industrial sector, it can be considered
a robust technology. However, robustness for destroy-
ing chemical weapons, and especially large segments
of energetic rocket propellants, remains to be demon-
strated. Adaptation of plasma devices for the destruc-
tion of chemical weapons will require (1) special han-
dling equipment for the safe introduction of shells,
rockets, and land mines; and (2) further development
of the torch and chamber designs to ensure the destruc-
tion of agent and the production of effluents that can be
scrubbed and burned or converted to slag and sent to a
landfill. Meeting these requirements will entail a much
more extended development and testing program than
the one being undertaken for the ACWA demonstra-
tion phase. The program would have to ensure that the
energy released from the processing of rocket propel-
lants can be controlled.
Monitoring and Contro/
The committee was not given detailed design pa-
rameters for the full-scale units. A smaller demonstra-
tion unit has been installed and is being operated. The
technology provider plans to use the monitoring and
control systems currently in use at DOD chemical-dis-
posal facilities and laboratories. Demonstration testing
may show that the proposed monitoring and control
strategies are effective, but the committee does not have
sufficient information to make an evaluation at this
time.
Applicability
Conceptually, plasma technology is applicable to all
assembled chemical weapons and could be used at any
of the chemical weapons storage sites. However, the
proposed process would have to overcome the engi-
neering hurdles described above to treat the various
components of assembled chemical weapons.
OCR for page 82
82
Process Safety
ALTERNATIVE TECHNOLOGIES FOR DEMILITARIZATION OF ASSEMBLED CHEMICAL WEAPONS
The unique equipment proposed by the Burns and
Roe team includes an explosion chamber, the PWCs, a
PAS, and a product-gas collection and storage system.
The pressure and temperature in the explosion cham-
ber vary cyclically. When energetic material is being
fed, the chamber is at ambient conditions. When the
energetic material is initiated, the peak temperature and
pressure associated with the deflagration or detonation
of up to 2,000 grams of TNT are reached. When the
product gas is vented, the pressure and temperature re-
turn to ambient conditions.
The PWCs operate at very high temperatures but at
slightly negative pressure. Although the plasma tem-
perature is estimated by the technology provider to be
in the range of 15,000°C (27,032°F), the interior PWC
wall surface is expected to be much lower (1,650°C
t3,000°F]; the temperature of exterior PWC surface
will be lower still (about 66°C t150°F]~. The PWC dis-
charges molten material into ladles for cooling.
The full-scale PAS receives gas from the PWCs at
about 1,100°C (2,012°F) and at rates up to 2,000 lb/hr.
The gas is quenched, scrubbed, and filtered before be-
ing pressurized to 100 psig for storage at ambient tem-
perature. The explosion chamber and the PWCs oper-
ate in a batch mode, and the product-gas collection
system includes a hold-test-release step before the gas
is stored in bulk. Thus, despite the uncertainties about
adequate exposure of the various input materials to the
high temperature of the plasma described earlier, the
presence of any chemical agent can, in principle, be
determined prior to the gaseous effluent being released
to storage for subsequent use.
Worker Health and Safety
ACWA demonstration tests are planned to confirm
that excessive energy will not be released when rocket
propellant reacts in PWC B and that the propellant will
not detonate. The results of these tests should be thor-
oughly analyzed.
The explosion chamber and the PWCs, including the
feed systems, dunnage shredder, and molten material
discharge systems, are operated remotely and are inter-
locked. Ease of maintenance should be integral to the
PWC design, particularly the replacement of the torch
electrodes, the repair of the PWC refractory liner,
access to the interior of the PWC, and operation of the
molten-material discharge valve. Although worker in-
teractions with high-temperature equipment/material or
rotating equipment should he minimized hv the con
. . . . ,
_ ,
trots ant' cosign features, worker hazards will probably
be higher in the presence of high-temperature systems
than in the presence of lower temperature systems.
Other worker hazards include the use of a large
amount of argon, CO2, or N2 (all asphyxiants), the pro-
duction of pressurized flammable gas, and an electrical
power system of 440 to 700 V and 800 amps. None of
these hazards is unique, however, and the risks can be
minimized with proper precautions. Worker interac-
tions with hazardous chemicals will be limited to caus-
tic for the off-gas scrubber and acid for the neutraliza-
tion of scrubber brine.
Public Safety
A substantial amount of flammable gas will have to
be stored, whether the product gas is burned on site or
shipped off site. A large explosion or deflagration in-
volving this gas could cause an on-site hazard and, po-
tentially, an off-site hazard from the direct thermal ef-
fects or overpressure forces. A greater concern is the
potential damage from explosions to containment struc-
tures that could lead to a release of agent. Explosion
hazards are common in industry and can be minimized
by good design and operation.
Cooling water is circulated through the plasma torch
to keep it from melting at the high plasma tempera-
tures. A leak in the cooling system could spray water
into the plasma. If the leak is sudden, rapid vaporiza-
tion could cause a pressure pulse that might overload
the downstream gas-handling equipment. Then, un-
treated agent could be released into the surrounding
room through the torch opening in the top of the PWC.
Similar "puffing" hats been Nerved in comhuLstion
. . .
.
equipment when excessive back pressure occurs. If the
leak is gradual, the resulting steam would dissociate in
the plasma forming hydrogen and oxygen gas that
could recombine and explode if the mixture is in the
flammable range above its autoignition temperature.
The effect of liquid water introduced into a plasma in
the presence of other species present in PWCs must be
determined before larger scale experiments are per-
formed. The normal PWC operating conditions appear
OCR for page 83
BURNS AND ROE TECHNOLOGY PACKAGE
to be outside the flammability range for hydrogen, but
the effect of the additional water (from a leak in the
torch cooling system) could create an explosive com-
bination. (For example, the presence of a steam diluent
would raise the autoignition temperature; whereas, an
argon diluent would decrease the autoignition tempera-
ture EKumar and Koroll, 19951~. If some water is not
completely vaporized, it would fall into the molten
material at the bottom of the PWC, and a metal-water
reaction could create a pressure pulse. These mecha-
nisms should be investigated further, unless the prob-
ability of the failure of the torch is determined to be
very low.
The technology provider is aware that torch failure
is a concern, and the potential for an explosion has been
reduced by the torch design and by redundant flow and
pressure controls that would actuate fast-closing valves
on the water feed as well as the waste feed in the event
of a failure.
Testing is planned to validate that agent does not
reform and that other hazardous materials (e.g., Sched-
ule 2 compounds and dioxins) do not form as the PWC
effluent cools. The potential formation of metastable
species (e.g., C2H2, HCN, C2N2) that could be quenched
from the rapid cooling of product gas should be thor-
oughly investigated.
Human Health and the Environment
Burns and Roe states that there will be no gaseous
air emissions and no liquid discharges from the inte-
grated system and that the solid waste will consist only
of metal ingots, vitrified material, and possibly scrub-
ber salts. The technology provider has also indicated
that the scrubber salts might be recycled to the PWC
and vitrified with sand to produce a very stable solid
waste. Thus, it is claimed in the proposal that there
would be virtually no impact on human health or the
environment. However, the committee has identified
some issues that must be addressed during the develop-
ment of the integrated process.
Effluent Characterization and Impact on Human
Health and Environment
The primary solid-waste streams include fly ash
material caught in filters, scrubber salts from the PAS,
83
and metal ingots and slag from the PWCs. The treat-
ment temperature for metal parts is expected to exceed
the required 5X conditions; therefore, metal parts
treated in the PWCs should receive a 5X designation.
The technology provider plans to explore the option
of recycling liquid scrubber effluent with fluxing
agents, such as lime and sand, in a PWC to generate a
vitrified solid waste. The treatment of scrubber liquor
by vitrification in the plasma unit has not been proven.
The committee's concerns relate to the behavior of salts
at high temperature and whether the acid components
could be incorporated into the melt without being re-
leased. For example, NaC1 salts could react with SiO2
at high temperatures to form gaseous SiCl4; also, NaF
salts could react with SiO2 to yield SiF4.
The PWCs produce the primary gaseous discharge.
The technology provider proposes that this gas will be
passed through a PAS to a holding tank. The commit-
tee is concerned that a PAS designed for fully oxidized
gas may not be as effective for gas generated under
reducing conditions in the PWCs. Whether reducing
conditions exist will depend on the plasma feed gas.
The performance of the PAS must be evaluated at the
design operating conditions and for the actual product
gas.
The committee concluded that some significant de-
sign changes may be required to the baseline PAS to
optimize its performance for the product gas. For ex-
ample, the PAS being used by Burns and Roe in the
ACWA demonstrations includes a venturi scrubber to
control particulates. Because the product-gas flow rate
for the PWC being demonstrated is only on the order of
140 SCFM, the gas velocities may not be sufficient for
the venturi to remove particulates effectively.
The technology provider presented no data on the
effluent characterization if the product gas is burned as
boiler fuel. Contrary to the technology provider's claim
that there would be no air emissions, the committee
concluded that small amounts of acid gases, including
NOX, SOx, HC1, and HE, may be generated during the
burning of plasma-generated product gas. The NOX and
SOX originate from the high-temperature burning of the
gas; HC1 and HE are produced with the chlorine and
fluorine (originally in the agent) that may not be com-
pletely removed by the scrubber (typical scrubber
efficiencies are 99.9 percent or greater). In addition,
the boiler burner systems must be designed to burn
OCR for page 84
84
ALTERNATIVE TECHNOLOGIES FOR DEMILITARIZATION OF ASSEMBLED CHEMICAL WEAPONS
relatively low heating-value gas efficiently to prevent
the release of unburned organics and other trace spe-
cies of environmental concern.
.
Semivolatile and volatile metals, such as lead, cad-
m~um, and arsenic, are expected to volatilize in the
PWC and condense downstream as a fine fume of sub-
micron-sized particles. Thus, the particulate control
device will be challenged by a fine metal fume with
particulate sizes that are difficult to capture. In addi-
tion, this metal fume would be pyrophoric. The tech-
nology provider indicated during meetings with the
committee that high-efficiency particulate air (HEPA)
filters would be added to the PAS to control the metal
fume. This addition will have to he evaluated to deter
. . .~ ~. . in-. .
.
mine ~ a non~amman~e bitter would be required. Also,
the pressure drop associated with the additional filter
would have to be accounted for in the design of the
system.
Completeness of Effluent Characterization
The technology provider has stated that the operat-
ing temperature in the plasma zone is about 15,000°C
(27,032°F) and that molecules subjected to this tem-
perature will be dissociated into atomic components.
However, all components may not be subjected to the
temperature of the plasma. The specific characteristics
of the product gas depend on the constituents in the
waste material being fed to the chamber and the tem-
peratures of the plasma and bulk gas. The technology
provider currently has no data on the actual character-
istics of the PWC effluent gas for the feeds expected
from the disassembly of chemical munitions. The tech-
nology provider has calculated the thermodynamic
equilibrium constituents of the gas with the assump-
tion that the gas reached the plasma temperature (or at
least a very high temperature). These calculations do
not address product constituents from material that
does not reach the high temperatures of the plasma zone
because of bypass or because of kinetic limitations that
allow metastable molecules to persist. A more com-
plete chemical analysis of product gas generated at pi-
lot scale will be necessary, including both major con-
stituents and trace species of environmental concern.
After being treated in the PAS, gas from the plasma
unit will be passed to a pressurized holding tank. Based
on the data in Table 5-5, and assuming compression to
100 psi", cooling to 25°C (77°F), and a holding time of
1 hour, the required tank volume will be approximately
14,300 ft3.
The gas will be sampled and analyzed for agents by
ACAMS and DAAMS. The technology provider also
proposes using a continuous emissions-monitoring sys-
tem consisting of a Fourier transform infrared (FTIR)
analyzer and an unspecified particulate-matter moni-
tor. Once the product gas has been certified to be agent
free, it may be used as a boiler fuel. The proposed gas
analysis will not analyze for trace organic by-products
or metals. Although the FTIR system can measure
some species to ppb levels, it may not be sensitive
enough to characterize fully trace organic and metallic
species of environmental concern on a continuous
basis.
The committee is also concerned about the deposi-
tion of materials on the walls of the hold-up chamber
that could be vaporized or resuspended when the cham-
ber is evacuated. A rigorous characterization protocol
for the hold-test-release system must be developed and
validated prior to implementation, regardless of the fi-
nal disposition of this gas stream.
Effluent characterization and chemical analysis of
the product gas are scheduled as part of the ACWA
demonstration phase. A careful, meticulous study of
the effluent gas will be critical to the evaluation of this
technology. The data should include the identification
of any organic intermediates that would be included in
an HRA. The committee is concerned that the effluent
characterization when CO2 or N2 is used as the plasma
feed gas will not be valid when argon is used. Testing
should be done with the specific plasma feed gas pro-
posed for the full-scale system.
-
-
Eff/uent Management Strategy
The strategy for effluent management proposed by
the technology provider is designed to eliminate all liq-
uid discharges and hazardous-waste discharges. Bulk
metals are melted in the plasma units and turned into
solid ingots, which are expected to meet the 5X decon-
tamination criteria. Dunnage and miscellaneous solid
waste will be treated on site in a separate PWC.
Scrubber discharge, which includes aqueous waste
containing salts, may be treated on site in a PWC or
processed in a brine reduction system prior to disposal
OCR for page 85
BURNS AND ROE TECHNOLOGY PACKAGE
in a landfill. If a PWC is used, the scrubber discharge
liquid will be mixed with sand or other fluxing agents
and then fed to the plasma unit where the water will be
evaporated and the solids vitrified. No data were pro-
vided to the committee on this process, and the com-
mittee questions whether the material can be melted
without releasing acid components of the scrubber ef-
fluent during vitrification as SiCl4 (gas) or SiF4 (gas).
If the baseline brine reduction system is used instead,
the technology provider will have to demonstrate that
excessive particulate emissions from the system will
not occur. The Tooele Chemical Agent Disposal Sys-
tem brine reduction system failed its environmental
testing because of such emissions, and the brine is cur-
rently being shipped off site for disposal in a landfill.
Management of trace metals is also a potential con-
cern. The technology provider did not characterize the
fly ash that would be collected in the filters of the PAS,
which could contain a large amount of the trace metals
volatilized in the plasma unit. This effluent stream will
be a hazardous waste that will have to be solidified
prior to final disposition. If the formation of soot is not
prevented by steam injection, a significant amount of
finely divided carbon could be present in the effluent
as graphite or soot.
In general, the product gas from the PWCs will con-
sist of a variety of organic compounds of uncertain
composition. The high temperatures and oxygen defi-
cient (or even reducing) conditions (depending on the
plasma feed gas) lead the committee to believe that
many of the compounds that can be present in trace
quantities in the emissions from combustion systems
will probably be present in higher concentrations in the
gaseous streams from this process. Although the tech-
nology provider proposes capturing and holding this
stream for analysis, the committee believes that this
will be difficult. The technology provider has presented
no data to demonstrate the feasibility of this type of gas
capture, containment, and characterization.
The committee also questions the feasibility of burn-
ing this gas in a boiler. The high chlorine, sulfur, phos-
phorus, and nitrogen content of the raw materials will
result in a complex mixture of compounds that will
have to be removed from the gas stream prior to burn
.
1ng, a difficult, if not daunting, task. The elemental
moieties will also create a gas stream with a composi-
tion very different from traditional gaseous fuels. The
"7 1
85
predicted composition after scrubbing (Table 5-5) in-
cludes several toxic compounds listed in the Clean Air
Act Amendments. The committee, therefore, believes
that this technology may encounter significant difficul-
ties in satisfying the risk-assessment and risk-minimi-
zation requirements for boilers and industrial furnaces.
Resource Requirements
The major resource requirements for this process are
water, power, argon (or other plasma feed gas), and
caustic. During operation, 40 gallons per minute of
water, 600 SCFM of argon, and 8500 lb/hr of caustic
will be required (Burns and Roe, 1997~. Although the
annual consumption of these materials was not esti
, .. .. . . . · . ..
mated oy tne recnno~ogy provider, tne committee esti-
mates that 5,000 hours of operation per year would re-
quire 12 million gallons of water, 180 million cubic ft.
of argon, and 42.5 million lb of caustic. The technol-
ogy provider estimates that the plasma torches will re-
quire 6 MW of power. Each PWC requires 0.5 kWh of
electrical energy per pound of material feed. The tech-
nology provider has used this value to estimate energy
requirements for all of the feed types, including agents,
energetics, metal components, DPE suits, and dunnage.
Environmenta/ Compliance and Permitting
Only a few plasma units have received permits for
waste processing in the United States to date. The
technology provider has not provided a definitive permit-
ting strategy for the unit beyond declaring that the sys-
tem would not be permitted under RCRA incinerator-
permitting procedures. The regulatory definition of an
incinerator includes plasma-based treatment systems
that burn waste with oxygen in enclosed chambers or
uses afterburners. In the Code of Federal Regulations
40 CFR 260.10 Definitions, a plasma or incinerator is
defined as "any enclosed device using a high intensity
electrical discharge or arc as a source of heat followed
by an afterburner using controlled flame combustion
and which is not listed as an industrial furnace." Be-
cause boilers are industrial furnaces, the proposed con-
figuration would probably not be interpreted as an in-
cinerator unless oxygen is used as the plasma feed gas.
The committee identified two alternative permitting
routes that might be followed for a plasma-treatment
OCR for page 86
86
ALTERNATIVE TECHNOLOGIES FOR DEMILITARIZATION OF ASSEMBLED CHEMICAL WEAPONS
process that generates gases that are subsequently
burned in boilers. First, the permitting process could
follow 40 CFR 264, Subpart X, Procedures for Miscel-
laneous Treatment Units:
A miscellaneous unit must be located, designed, con-
structed, operated, maintained, and closed in a manner
that will ensure protection of human health and the envi-
ronment. Permits for miscellaneous units are to contain
such terms and provisions as necessary to protect human
health and the environment, including, but not limited to,
as appropnate, design and operating requirements, detec-
tion and monitoring requirements, and requirements for
responses to releases of hazardous waste or hazardous
constituents from the unit. Permit terms and provisions
shall include those requirements of other rules that are
appropriate for the miscellaneous unit being permitted.
With Subpart X permitting, the permit writer uses the
relevant rules as a guide, and permitting authorities are
likely to use the most recent incinerator standards as
. · .
tne appropriate rules, as they generally do with ther-
mal-treatment units.
If the plasma-generated product gases are burned in
a boiler, regulatory authorities could also opt to impose
the boilers and industrial furnace (BIF) permitting pro-
cedures. In this case, the authorities could regulate the
unit as a boiler burning hazardous waste. BIF rules have
been developed, and the permitting procedures have
been well defined. The EPA has announced plans to
develop Clean Air Act Maximum Achievable Control
Technology (MACT) standards for boilers burning haz-
ardous waste over the course of the next few years.
These new standards will probably be in place prior to
the construction of a full-scale PWC system. Thus, al-
though the PWC system is not likely to be regulated as
an incinerator, the permitting procedures would be
. .
similar.
STEPS REQUIRED FOR IMPLEMENTATION
The full-scale implementation of this technology
will require demonstration with actual chemical agents
and weapons. Some of these studies are scheduled for
the ACWA demonstration. There is little doubt that the
highest plasma-torch temperatures will destroy mustard,
GB, and VX, but no testing has been done to demon-
strate that the agents remain in the plasma zone long
enough to be destroyed. Nor are there detailed analytical
data to indicate side reactions or unpredicted products
· ~ ~ ~ ~
tnat couth result te.g., dioxins, SOxFy, and OFT.
A more thorough evaluation of the proposed tech-
nology will be possible when a full-scale PWC design
is available for modeling gas flow rates and evaluating
the exact placement of nozzles and ports through which
munition materials would be introduced into the hot
plasma zone. The following list includes the most criti-
cal steps the technology provider must take before pro-
ceeding to implementation:
1. Determine the effect of sudden water injection
into the plasma torch in the presence of argon,
nitrogen, carbon dioxide, and other species
present in the plasma system. Include an evalua-
tion of the effect of gases present in the PWC on
the flammability range of hydrogen gas.
2. Determine the likelihood of the release of un
treated agent and other hazardous contaminants
from the PWC if the gas generation rate is unex-
pectedly high (e.g., due to a cooling-water leak,
the inadvertent introduction of explosive mate-
rial into the chamber, or a rapid deflagration of
propellant).
3. Conduct a thorough analysis of the product gas
generated from each PWC using the plasma feed
gas proposed for full-scale operation. This analy-
sis should include the identification of organic in-
termediates that would be of concern in an HRA.
4. Establish the efficacy of pollution-control equip-
ment in removing hazardous compounds (e.g.,
NOx, SOx, HC1, and metals) from the product gas.
-, 5. Perform a larger-scale demonstration of PWC op
eration, that includes the hold-test-release step.
FINDINGS
Finding BR-1. No tests have been done involving ac
. . · .
O
dual cnemlca~-agent or propellant destruction in a PWC.
Tests with agent and M28 propellant were planned for
the demonstrations being conducted between February
and May of 1999, but no data were available to the
committee at the time of this writing.
D 1
. . .
Finding BR-2. Scale-up from the small PWC units in
existence to the very large units proposed is likely to
present significant scientific and engineering challenges.
.
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BURNS AND ROE TECHNOLOGY PACKAGE
Finding BR-3. Tests performed with one plasma feed
gas may not be indicative of PWC performance with a
different gas. Because different plasma feed gases have
different thermodynamic and chemical properties, the
choice of the plasma feed gas could have a significant
impact on the performance of the system. For example,
the electrical power requirements will be determined,
in part, by the plasma feed gas. Electrode wear may
also depend on the type of gas, and product gas compo-
sition will vary.
Finding BR-4. The technology provider's proposal for
recycling the liquid-scrubber effluent through the PWC
to vitrify the salts may not be practical. If scrubber li-
quor is fed to a PWC, some of the contaminants may
simply revolatilize. In addition, NaC1 and NaF salts
could react with SiO2 at high temperatures to form gas-
eous SiCl4 and SiF4, respectively (both hazardous
materials).
Finding BR-5. The maintenance of negative pressure
within the PWC has not been demonstrated under mu-
nition-processing conditions. Pressure excursions that
produce positive pressure in the PWC vessel could re-
lease product gas to the surrounding room. Some up-
sets that could result in moderate to severe pressure
excursions are listed below:
· A leak in the torch-cooling system could release
water into the PWC, and rapid steam formation
could pressurize the vessel. Water leakage might
87
also lead to more severe pressure excursions or
even explosions.
· Energetic material that remained in a mortar or
projectile and was introduced into a PWC could
detonate upon heating, which would generate a
pressure pulse. The severity of this pulse would
depend on the type and quantity of explosive.
· An improper cut of the rocket motor could allow a
larger-than-design piece of propellant to be intro-
duced into the PWC. If the gas production rate
from the propellant exceeds the capacity of the
downstream PAS, the vessel could overpressurize.
The technology provider should investigate the likeli-
hood of such events and determine their potential im-
pacts on the operation of the PWCs.
Finding BR-6. Combustion of plasma-converted gas
in a boiler faces three major hurdles: (1) to avoid being
permitted under RCRA as a boiler burning hazardous
waste, the gas may have to be delisted; (2) the gas may
require significant scrubbing to remove compounds
that are unsuitable as boiler feedstock; and (3) the boiler
will have to be configured to burn gas that has a low
heating value efficiently in order to avoid generating
unacceptable emissions.
Finding BR-7. Although a PWC may not be consid-
ered to be an incinerator by permitting authorities, the
most likely permitting procedures for a PWC would be
similar to those used for incinerators.
Representative terms from entire chapter:
feed gas
