EPA/540/2-89/025
SUPERFUND TREATABILITY
CLEARINGHOUSE
Document Reference:
Ogden Environmental Services, Inc. "BOAT Treatability Data for Soils, Sludges and
Debris From the Circulating Bed Combustion (CBC) Process." Technical report
prepared for U.S. EPA. 31 pp. June 1987.
EPA LIBRARY NUMBER:
Super-fund Treatability Clearinghouse - EWHC
PHASE DO NOT FROM LIMY
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SUPERFUND TREATABILITY CLEARINGHOUSE ABSTRACT
Treatment Process: Thermal Treatment - Circulating Bed Combustion
(CBC)
Media: Soil/Clayey
Document Reference: Ogden Environmental Services, Inc. "BOAT Treat-
ability Data for Soils, Sludges and Debris From the
Circulating Bed Combustion (CBC) Process."
Technical report prepared for U.S. EPA. 31 pp.
June 1987.
Document Type: Memo and Conference Paper
Contact: Major Terry Stoddart
U.S. DOD/AFESC
Bldg 1117
Tyndall Air Force Base, FL 32403
904-283-2949
Site Name: Circulating Bed Combustion Demonstration Facility
(Non-NPL)
Location of Test: California
BACKGROUND; The two papers provide a general overview of the Ogden
circulating bed combustion and summary data of both PCB laden soils for
EPA-TSCA and a test on RCRA liquid organic wastes for the California Air
Resources Board (CARB). This abstract will discuss the results of the PCB
test, which was planned, monitored and approved by the EPA.
OPERATIONAL INFORMATION; The primary CBC components are the combustion
chamber, hot cyclone collector, flue gas cooler, baghouse, and stack.
Auxiliary systems include feeders (solids, liquids, sludges), forced-draft
and induced-draft fans, ash conveyer, compressed air, cooling tower, and
building ventilation. Operating parameters, schematic diagram and cost
estimates are provided.
Atmospheric primary air is pumped into the lower portion of the
combustion chamber where the bed material is fluidized by turbulent mixing
of the air and solids. Larger solids gravitate downward to form a more
dense fluidized bed in the lowest combustor zone. The forced-draft primary
air carries smaller solids up to the top of the combustor. Secondary air
is supplied to various locations in the combustion chamber to ensure
complete combustion and minimize formation of nitrogen oxides (NO ).
Auxiliary fuel and pressurized contaminated soil feed are individually
introduced into the lower combustion chamber. Capability also exists to
feed liquid wastes. Dry limestone sorbent is added to control gaseous
emissions of sulfur, phosphates, chlorines, or other halogens.
Elutriated solids are separated from the flue gas by a hot cyclone and
reinjected into the lower combustor using a proprietary non mechanical
seal. Injection, burning and reaction of fuel, contaminated soil feed,
3/89-46 Document Number: EWHC
NOTE: Quality assurance of data may not be appropriate for all uses.
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sorbent, and ash components are the inputs and outputs of a continuing
chemical process which destroys the hazardous wastes.
A trial burn of PCB-contaminated soils was completed in GA Technologies
transportable Circulating Bed Combustor (CBC). Over 4000 pounds of soil
containing 1% PCB were treated in three identical 4-hour runs at 1800° F.
The sampling and analysis and the resulting data were obtained in
accordance with the QA/QC protocol of EPA. Third party sampling and
analysis contractors were used (along) with on-site and in-lab observation
by EPA.
PERFORMANCE! Destruction and removal efficiencies (DREs) were greater than
99.9999% and PCB levels in combustor ash were less than 200ppb (see
Table 1). No chlorinated dioxins or furans were detected in the stack gas,
bed ash, or fly ash. In addition, no significant concentrations of the
Products of Incomplete Combustion (PICs) were detected. Combustion
efficiencies were greater than 99.9X, with CO concentrations less than 50
ppm and NO concentrations less than 75 ppm. Particulate emissions were
generally Below 0.08 grain/dscf and HCL emissions were maintained below 4.0
Ib/hr by introducing limestone directly into the combustor. It is noted
that PCB test data led to the first TSCA permit for transportable PCB
incinerator operation in all 10 EPA regions.
CONTAMINANTS;
Analytical data is provided in the treatability study report. The
breakdown of the contaminants by treatability group is:
Treatability Group CAS Number Contaminants
W02-Dioxins/Furans/PCBs 1336-36-3 Total PCBs
3/89-46 Document Number: EWHC
NOTE: Quality assurance of data nay not be appropriate for all uses.
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TABLE 1
PCB TRIAL
Parameter
Test Duration, hr
Operating Temperature, °F
Soil Feed Rate, Ib/hr
Total Soil Feed, Ib
PCB Concentration in Feed.
DRE X
PCB Concentration
- Bed Ash, ppm
- Fly Ash, ppm
Dioxin/Furan Concentration
- Stack Gas, ppm
- Bed Ash, ppm
- Fly Ash, ppm
Combustion Efficiency, %
Acid Gas Release, Ib/hr
Particulate Emissions,
grain/scf (dry)
Excess Oxygen, %
CO, ppm
co2, %
N0x, ppm
BURN OPERATIONAL
TSCA
Requirement
4
-
-
-
ppm
>99.9999
<2
<2
-
-
-
>99.9
<4.0
<0.08
>3.0
-
-
DATA AND
1
4
1800
328
1592
11,000
99.999995
0.0035
0.066
ND
ND
ND
99.94
0.16
0.095
7.9
35
6.2
26
TEST RESULTS
Test Number
2
4
1800
412
1321
12,000
99.999981 99
0.033
0.0099
i
1 ND
ND
ND
99.95
0.58
2 0.043
6.8
28
6.0
25
3
4
1800
324
1711
9,800
.999977
0.186
0.0032
ND
ND
ND
99.97
0.70
0.0024
6.8
22
7.5
76
2 ND - Not Detected
Derived from 2-hour makeup test
Note: This is a partial listing of data.
information.
Refer to the document for more
3/89-46 Document Number: EVHC
NOTE: Quality assurance of data may not be appropriate for all uses.
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OGDEN ENVIRONMENTAL
SERVICES, INC.
POST OFFICE BOX 85178 10955 JOHN JAY HOPKINS DRIVE
SAN DIEGO CALIFORNIA 92138-5178 SAN DIEGO, CALIFORNIA 92121
HAROLD R DIOT
DIRECTOR SALES AND MARKETING
i6'9l 455-2383
June 3, 1987
Mr. James Antizzo
U.S. EPA ( Mail Code WH-548E)
401 M Street, S.W.
Washington, D.C. 20006
Dear Mr. Antizzo:
The enclosed abstract and package of information is sent to you in response
to the Agency's need for treatability data for soils and debris to use in
establishing BOAT standards under the land disposal restrictions program.
We are pleased to respond to this need as stated in a May 18, 1987 letter
to Mr. Richard Fortuna of the Hazardous Waste Treatment Council from
Mr. Bill Hanson, Acting Chief, Site Policy and Guidance Branch.
We think that the attached Abstract and brief answers to the "TREATABILITY
STUDY ATTACHMENT" reflect the excellent performance of our Circulating Bed
Combustion technology and the responsible and precise controls and
standards of the Agencies involved in our test work.
We look forward to supplying any additional information. Please call me at
(619) 455-2383 or Derrell Young at (619) 455-3045 if you have any
questions.
Sincerely,
Harold R. Diot
HRDrmat
Enclosure
cc: Richard Fortuna, Hazardous Waste Treatment Council
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ABSTRACT
BOAT TREATABH.ITY DATA FOR SOILS, SLUDGES AND DEBRIS
FROM THE
CIRCULATING BED COMBUSTION (CBC) PROCESS
June 3, 1987
The CBC has demonstrated its effective destruction of hazardous and
toxic compounds in soils, sludges and liquids. These demonstrations have
been done in tests in commercial size equipment in a facility recognized as
one of the leading fluid bed research centers in the world. There have
been over 5000 hours of testing logged in this facility. The key tests
discussed below represent only a small sample of the data available.
The two key tests discussed here and in the attached brief answers to
the "TREATABILITY STUDY ATTACHMENT" include a test on PCB for EPA-TSCA and
a test on RCRA compounds for the California Air Resources Board (CARB).
Both of these tests were planned, monitored and approved by the respective
agencies. The sampling and analysis and the resulting data obtained was
gained under the QA/QC protocols of these agencies. Third party sampling
and analysis contractors were used under with on-site and in-lab
observation by these agencies. The PCB test data led to the first TSCA
permit for transportable PCB incinerator operation in all 10 EPA regions.
The CARB data (along with the PCB and other test data) have formed the
basis of the "operating boundary" permit conditions for the RCRA RD&D
permit given by EPA Region IX for the facility.
Some major points regarding the data:
o The FCB tests were done on actual site soils (clay-like, rocky
material).
o Greater than 99.9999X DRE was obtained on PCB and no dioxin or
furan was detected and ash was well below TSCA requirements.
o PICs were studied to the extent that all peaks in the National
Bureau of Standards Mass Spectral library were quantitated.
1
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o PICs have been related to continuously monitored CO and HC
emissions.
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TREATABILITY STUDY
ATTACHMENT '
1. Facility identification, description, and waste characteristics.
1.1. Identification
Ogden Environmental Services, Inc. (OES)
Circulating Bed Combustion (CBC) Demonstration Facility
10955 John J. Hopkins Drive
San Diego, CA 92121
EPA Permit Number: CAD 981613789
1.2. Description
A CBC thermal destruction facility including all auxiliary hardware
for solids, liquids or sludge waste treatment are instrumented specifically
for rigorous data collection. A schematic and photographs of the facility
are shown in Figures 1.2-1, 1.2-2, and 1.2-3.
This CBC is a transportable treatment unit with a 2 million Btu/hour
thermal rating*. The transportable CBC has a TSCA permit for PCB soils
treatment in all 10 EPA regions. This CBC facility also has an EPA-RCRA
Research, Development and Demonstration (RDD) permit for test work on RCRA
waste. The waste characteristics tested already and allowed to be tested
by the EPA RDD permit are described in Section 1.3 below.
OES provides full waste thermal destruction services with
transportable CBCs up to 10 million Btu/hour and with fixed CBCs up
to over 50 million Btu/hour.
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840311-3C
Fig. 1.2-2. OES 16-in. pilot-scale circulating bed combustor
80238-19C
Fig. 1.2-3. Pilot-scale CBC control console and data acquisition
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1.3. Waste Characteristics
1.3.1. Hazardous Wastes Already Tested* in CBC
o Soil containing up to:
- 12,000 ppm PCS (arochlor 1260)
2,100 ppm 1,2,4 trichlorobenzene
- 350 ppb total furans (estimated)
7 ppb total dioxins (estimated)
o Liquids containing:
- Freon 113
Carbon tetrachloride
Hexachlorobenzene
Ethylbenzene
- Xylene
Trichlorobenzene
- Toluene
Sulfur hexafluoride
1.3.2. Hazardous Wastes Allowed for CBC Tests by EPA RDD Permit
All RCRA wastes listed in 40 CFR, number 261, except:
1) F020, F021, F022, F023, F026, F027, F028 wastes (specific dioxin
and furan compounds) with a concentration of 1 ppm or higher.
2) Wastes with a concentration of greater than 1000 ppm mercury (Hg,
lead (Pb), arsenic (AS), barium (Ba), cadmium (Cd), chromium
(Cr), selenium (Se), or silver (Ag).
Successful test demonstration work on many other materials not listed
as hazardous has been done including: aluminum smelter potliners,
refuse derived fuels, high sulfur coals, etc.
6
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3) Wastes with a PCB content of 50 ppm or greater, (only if the
Permittee's TCCA permit to burn PCB's is no longer valid . . .
note this permit allows up to 9,800 ppm PCB soils).
A) Chemical warfare agents.
5) Radioactive materials.
6) Forbidden and Class A explosives as defined in 40 CFR 173.51 and
173.53.
7) Waste with a total organic sulfur content greater than 5 wt.Z.
2. Treatment Technology Selected for Treatability Testing
2.1. Treatment Category (i.e., Thermal Destruction. Physical Chemical'r
Biological. Solidification/Stabilization)
Thermal destruction
2.2. Criteria for Technology Selection
In-house technology or technology provided by a vendor. Vendor name.
Reason for selection.
The CBC is in-house technology. The CBC technology for hazardous
waste was developed by GA Technologies, Inc. (GA). GA and Ahlstrom of
Finland formed Pyropower Corporation in 1980 to supply CBCs for the U.S.
boiler market. Pyropower and Ahlstrom have many CBC units installed and
operating worldwide burning a variety of fossil fuels, biomass and wastes.
OES has a licensing agreement to use the same CBC technology to develop and
build hazardous waste incinerators. Also, the 2 million Btu per hour CBC
facility and the key CBC program personnel were transferred to Ogden
Corporation as OES in December 1986, and OES continues to develop the CBC
technology for hazardous waste destruction.
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2.3. Process Description, Requirements and Limitations
The process description is given below.
Requirements
Requirements for operations vary depending upon the CBC size and feed
type. An example is given below for the 36-inch diameter CBC, the largest
transportable version. Note: ~10 MM Btu/hr . . . hazardous waste
treatment CBCs are available in sizes from ~16-inch diameter (2 MM Btu/hr)
to ~120-inch diameter (50 MM Btu/hr).
36-inch CBC Operating Requirements
o Temperatures
o Thermal Rating
o Auxiliary Fuel Required (if no
heat value of feed)
o Electricity (connected)
o Water
o CBC Area
1AOO°F to 1800°F (normal
range)*
10 MM Btu/hr
10 therms/hr
250 kva
None (closed loop cooling
system)
50 x 50 feet
Limitations
Feed limits for solids are ~l-inch ring size on the largest feed
input. Liquids/sludges must be pumpable. Ash melting limits
(glass-formers) in feed materials vary depending upon application.
Higher than 1800 F temperatures can be accommodated in the CBC but
have not been necessary to achieve the desired waste destruction.
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Typically, several wtJ of low-temperature «1600 F) melting material can be
handled without special procedures. We have developed procedures to handle
>30 wt% glass-formers.
Process Description
The CBC is a complete, self-contained thermal process plant capable of
destroying, through combustion, hazardous components of various contami-
nated solid feedstocks. It will produce inert by-products that satisfy
federal, state, and local regulatory requirements.
Commercial units in Europe and the U.S. are designed to burn a wide
variety of fuels such as coal, peat, wood wastes, municipal wastes, and
oil, primarily for the purpose of raising steam or generated electricity.
Application of this process to the treatment of hazardous wastes was
developed in the US since 1980 (Ogden Environmental Services, Inc. acquired
this technology in December 1987 from GA Technologies, Inc.).
The CBCs process advantages are derived principally from (1) the
extremely high fluidizing velocities and the resulting intrinsic turbulence
and (2) the recirculation of solids to the combustion chamber.
The ability of the CBC to efficiently destroy organic waste at low
combustion temperatures and low excess air levels without an afterburner
results in very high waste processing rates for given-sized hardware. With
typical operating conditions, the CBC system can handle a maximum soil
2
waste throughput of 1100 Ib/ft of combustor cross section and requires
only 850 Ib/h/ft of combustion air. This specific throughput is
significantly higher than can be obtained using other incineration
technologies. Thus, CBC units do more work than other equivalently sized
incinerator types.
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Major Equipment Components and Function
The primary CBC components are the combustion chamber, hot cyclone
collector, flue gas cooler, baghouse, and stack. Auxiliary systems include
feeders (solids, liquids, sludges), forced-draft and induced-draft fans,
ash conveyor, compressed air, cooling tower, and building ventilation.
Figure 2-1.1 is a schematic representation of the process.
Atmospheric primary air is pumped into the lower portion of the
combustion chamber where the bed material is fluidized by turbulent mixing
of the air and solids. Larger solids gravitate downward to form a more
dense fluidized bed in the lowest combustor zone. The forced-draft primary
air carries smaller solids up to the top of the combustor.
Secondary air is supplied to various locations in the combustion
chamber to ensure complete combustion and minimize formation of nitrogen_
oxides (NO ).
v x'
Auxiliary fuel and pressurized contaminated soil feed are individually
introduced into the lower combustion chamber. Capability also exists to
feed liquid wastes. Dry limestone sorbent is added to control gaseous
emissions of sulfur, phosphates, chlorines, or other halogens.
Elutriated solids are separated from the flue gas by a hot cyclone and
reinjected into the lower combustor using a proprietary nonmeehanical seal.
Ignition, burning, and reaction of the fuel, contaminated soil feed,
sorbent, and ash components are a continuing chemical process which
destroys th« hazardous wastes.
The loop design is such that essentially all of the pollution control
occurs in the combustion loop itself. Efficient mixing of the fuel, soil
feed, and combustion air assures that all hazardous organic constituents
are oxidized with minimum emissions of both CO and NO . Flue gas wet
scrubbers are not required.
10
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f.
u
(fl
CJ
ea
i
CM
00
-^
fa.
11
-------
The high velocity of combustion-air and circulating solids creates a
uniform temperature (^50 F) around the combustion loop which is controlled
at a value between 1400 F and 1800 F. Residence times in the combustor
range from about 2 seconds for gases to about 30 minutes for solid feed
material (less than 1.0-inch ring size).
During operation, ash is periodically removed from the CBC by means of
a water-cooled ash removal system. The hot gas leaving the cyclone is
cooled in a flue gas cooler; the fly ash escaping the cyclone is
continuously collected by baghouse filters. These filters reduce the
particulate loading in the flue gas from as high as 130 to 0.01 grains/scf
(the EPA RCRA particulate emission limit is 0.08 grains/scf). The fabric
filters are acid-resistant and normally operate at temperatures up to
350 F. No post-treatment of the dry, inert ash is necessary.
CBC Advantage
The extreme turbulence and high recirculation rates of the solids
within the combustor make the CBC combustion process relatively insensitive
to feed properties. The 100-to-l ratio of hot-inert-solids-to-feed and the
high internal combustor heat transfer ensures that moisture in the waste
feed rapidly evaporates with little (if any) depression in local combustor
temperature. The only significant effect of feed moisture on the
incineration process is on the combustor energy overall heat balance.
Energy that would otherwise go to processing contaminated soil must be used
to evaporate water (as with any thermal system).
The CBC is insensitive to large amounts of fines in the feed stream.
Feed fines benefit the solid circulation that produces the isothermal
combustor conditions.
The turbulence in the CBC atomizes liquid waste feeds, thereby
eliminating the need for troublesome spray nozzles which could clog. The
bed effectively disperses viscous sludges.
12
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The acid gases formed by chemical reactions are rapidly absorbed by
the large surface area of fine circulating sorbent (such as limestone or
other inexpensive local sorbent). The intermediate reactions form the
final ash products of benign salts such as CaCl and CaSO,. The rapid
combustion of the flue gas and quick neutralization of the acid gases
within the combustion chamber are in contrast to other incinerator types
that rely on afterburners to complete combustion and add-on scrubbers to
complete acid gas capture.
Avoiding the requirement for a wet scrubber not only simplifies
operation of the incinerator and avoids acid gas attack of internals
between the combustor and the scrubber, but also completely eliminates
aqueous waste streams.
Two features of the CBC make it much more energy-conserving in soil
decontamination applications. The first derives from the CBCs ability co-
destroy contaminants in a temperature range of 1400 to 1800 F - several
hundred degrees lower than required in other types of incinerators. This
ability to clean up soil without heating it to highly elevated temperatures
greatly reduces the amount of auxiliary fuel required in the CBC versus
other types of incinerators.
The second feature of the CBC that conserves energy is the very low
excess air required in the destruction of contaminants. Because of the
highly turbulent bed and intimate contact between the contaminated solids
and air, the CBC operates in the range of 201 to 40Z excess air. This
compares to several hundred percent excess air in a rotary kiln, for
example, where most of the air bypasses the soil without reacting with it.
Although much of the air bypasses the soil, it still picks up heat from the
rotary kiln and makes necessary additional auxiliary fuel to replace this
lost heat and additional water flow to cool the bypass air.
When an upset occurs in a CBC (e.g., fan failure, power outage, etc.)
the bed material slumps into the lower combustion chamber, thus retaining
pollutants in the limestone and ash. In contrast, the conventional
13
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bubbling bed is not easily slumped because lower velocities invite bed
agglomeration. When a scrubber is involved, as for kilns and grate
incinerators, scrubber bypass is required in an upset. Scrubber bypass can
release large amounts of untreated pollutants.
The key CBC components, the combustor, provides these benefits
inherently and automatically, without complicated controls. Other
components (pumps, fans, etc.) are standard hardware. Scrubbers or other
chemical treatment equipment are unnecessary. The innovation represented
by the CBC is in the total system, i.e., in the arrangement and particular
function that has been designed into the incinerator using this standard
hardware.
2.4. Rate of Process and Length of Treatment Time.
The largest transportable 36-inch CBC will process soils at up to _
12,000 Ib/hr on a 24-hour per day, 7-day per week basis. The system will
also process contaminated sludges and liquids concurrent with soils or
separately.
Length of treatment time is interpreted as residence time of materials
at temperature in the CBC combustion loop. There is a minimum "gas"
residence time and longer residence for solids as described below:
Gas Residence Time
The gas residence time is controlled by the superficial velocity in
Q
the combustion chamber, and is approximately 2.5 to 3 seconds at 1600 F.
Exact operating conditions are selected based on test and trial burn
results to meet or exceed all requirements. Upon leaving the combustor
loop, the gas flows through the flue gas cooler where it is cooled to
350 F, over * 6 second time interval. The gas temperature remains
essentially constant throughout the rest of the system, with about
/
3 seconds passing before discharge to the atmosphere.
14
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The gas residence time (at 1600 F) calculation is summarized as
follows:
Component
Combustion chamber
Chamber to cyclone
Cyclone
Cyclone to FGC
Length
(ft.)
35
12
20
24
Velocity
(ft./s)
20
50
50
50
Time at
1600°F
(seconds)
1.75
0.24
0.40
0.48
2.87
Solids Residence Time
Due to extensive backmixing and solids recirculation in the CBC, the
solids residence time at operating temperature is much greater than for the
gas. While this residence time is dependent on particle size and attrition
rates, on average the bed is replaced about twice per hour. Thus, a
typical solid residence time is about 30 minutes. Solids leave the
combustor through either the bed ash discharge or the gas exit in the
cyclone. Solids in the gas stream are cooled along with the gas, and are
separated in the baghouse. Bed ash is transferred by a water-cooled screw
conveyor, taking about 30 minutes to cool from operating temperature to the
cool ash temperature.
Not* that even very finely divided solids have a reasonably long
system residence time due to the solids recirculation.
2.5. Material Handling Equipment Requirements (i.e.. Material Transport
and Excavation)
Solids material transport to the 36-inch diameter CBC on a
remediation site typically involves loading a solids feed hopper once per
15
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day from a large storage pile or excavation area using a front-end loader.
From the solids feed hopper, the solids are activated and fed automatically
by mechanical feeders.
Sludge/liquid material transport involves pumping out of a surge tank
and feeding directly into the CBC. The surge tank may be sized to receive
daily, weekly or other periodic loads from the site.
Excavation equipment requirements vary depending upon the site.
Standard loader/excavators may be used on soils sites with digs up to 40'
deep. Special equipment (and/or shoring, etc.) may be required for deeper
excavations.
2.6. Pretreatment Requirements (i.e., Oversize Material. Removal,
Disaggregation, Sorting, Dewatering, Chemical/Physical Treatment, Control
of Volatile Release, Control of Particulate Release) Description Criteria
for Application
A solids size maximum of 1-inch ring size. Pumpable liquids/sludges
need no pretreatment (filtering, etc.) because there are no atomizers
required on the CBC. Dewatering of liquids stream is not necessary for the
process (dewatering may be an economic benefit). Some oversized impervious
materials such as metal parts may be washed and the surfaces certified
clean of contamination. The contaminated wash material would then be
incinerated in the CBC.
Volatile and particulate release in pretreatment is minimized due to
the minimal pretreatment required for CBC feeds. Fugitive dust/vapor
control for screening/shredding/crushing and solids handling typically
requires simple dust enclosures. Negative pressure systems or spray
wetting systems may be added in some cases as necessary. Volatile vapor
control is required usually only if thermal pretreatment (dewatering) is
used. This volatile vapor control would involve drawing hazardous vapors
through the inlet fans of the combustor or alternatively absorbing vapors
16
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on activated carbon or condensing the vapors and then burning the
contaminated residues.
Criteria for application of these pretreatment requirements may be
summarized as:
o Oversize Solids >1" - Screen, Crush - Dirt, rock, etc., 1" to A"
Screen, Shred - Metal, wood, paper, fibre,
etc., 1" to 4"+
Screen, Wash - Metal, rock, selected others
A"
o Dewater - If economics show favorable
o Volatile and To meet local, state and Federal standards
Particle Control -(may include insitu monitoring)
2.7. Post-Treatment Requirements. Description. Criteria for Application
Residuals from the CBC include dry cementitious (pozzulanic) ash.
This ash in site soils cleanups would include inert soils and limestone and
lime salts of chlorine, sulfur and other solid lime-absorbed materials.
Tests on RCRA and TSCA materials indicate such low organics levels in the
ash residue that the ash residue may be either delisted (RCRA) or
non-regulated (TSCA).
2.8. Byproducts and Other Process Effluent. Type. Quantities, and
Concentrations. Environmental Controls
Th« off-gas is primarily CO., 0., N and H.O vapor. CO and NO are
typically <150 ppm and HC1 and unburned HC (total) are typically <100 ppm.
Offgas particulate is «0.08 grains per acf as controlled by a baghouse.
The baghouse flyash and bedash are dry solids. These solids are
primarily silica sand and lime and lime salts (CaCl. or CaSO^) since dry
limestone is injected into the combustor to capture acid gas formers before
they leave the combustor. The resultant ash is a very low leachable
cementitious (pozzularius) dry powder. No wet scrubber sludge is produced.
17
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2.9. Monitoring and Data Collection Requirements (i.e., QA/QC Protocols)
Modified Method 5, VOST, (SW846 methods) solids sampling and analysis
procedures (methods, chain-of-custody) as approved by EPA have been used to
obtain the data supporting the CBC TSCA permit for PCB and the CBC HDD
permit for RCRA compounds.
3.0. Treatability Test
3.1. Scale Used for Testing (i.e.. Bench. Pilot, Full) and Scale-up
Limitations
A 16-inch diameter commercial-scale unit was used for test work.
There are no scale-up limitations as already demonstrated by demonstrations
in this commercial-size test rig as applied to other larger commercial
units burning varied solids/liquids whose bed cross-sections are many feet.
The data from the 16-inch rig has been basically the same as in the larger
rigs with no scale-up surprises.
3.2. Number of Tests Conducted Under Variable Conditions. Test Results in
a Summary Table Showing Both Operating Conditions and Performance Results
There have been over 5,000 test hours logged in the pilot plant on
various non-hazardous and hazardous feeds.
Two key examples of test data on hazardous feeds are given in
Tables 3.2-1 and 3.2-2 for the TSCA PCB test and the RCRA liquids test
(California Air Resources Board), respectively.
See also Appendix A for more details on the PCB test for TSCA.
18
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3.3. Performance Evaluation (i.e.. Removal Efficiency). Could Performance
be Improved? Hov? (Operating Conditions Change, Additional Pretreatment,
etc. )
Performance improvements are centered only in maintaining consistent,
reliable and optimum feed rates of sorbent (limestone) solids and the
contaminated solids and liquids feeds. The CBC turbulence and residence
time have demonstrated well above the required DREs at temperatures which
are much lower than other incinerators.
4.0. Processed Residual
A.I. Physical Chemical Characteristics and Analysis, Volume Increase or
Decrease
The dry ash produced has been well below TSCA standards for PCB (see
Appendix A) and has been at delistable levels, if such delisting were
appropriate, for RCRA materials.
Volume decreases of over 20 to 1 have been noted for some low-ash
liquids/sludges. Volume stays essentially constant for contaminated soils.
4.2. Regulatory Test Protocol Results (i.e.. EP Toxicity, TCLP. etc.).
Specify Test Performed
Organics have been quantified for PCB as given in Appendix A. Metals
leachability tests have not been performed, though there have been perti-
nent studic* on fluoride leachability.
4.3. Residual Disposal Method Used. Reasons for Selection
Pilot plant ash is either returned to the test customer or sent to a
Class I facility under contract to the test customer. Though the ash could
be delisted, the volume (a few drums) are too small.
21
-------
4.4. Cost Requirements (Per Unit of Time and Unit of Mass of Waste
Treated)
Costs depend upon the size of combustor and the type of feed.
Examples of CBC treatment costs on varied moisture content soil for 36-inch
and 104-inch diameter CBCs are given below:
Soil
Moisture
Z
10
16
30
Total
36-inch CBC
117
131
166
5/t
104-inch CBC
78
84
98
4.5. Permit Requirements (Type of Permit Required, Used)
The following 5 permits have been obtained for the pilot plant CBC:
(1) EPA-TSCA transportable PCB incineration permit - the first for all
10 EPA regions; (2) EPA-RCRA RD&D permit, the first in California;
(3) California Department of Health Services RD&D Permit (Draft) . . .
(also, a Mitigated Negative Declaration of no significance environmental
impact under the California Environmental Quality Act); (4) San Diego Air
Pollution Control District Permit including a hazardous emissions impact
assessment, and; (5) San Diego Industrial User Discharge Permit.
The commercial CBCs (nonhazardous fuels) have obtained air permits in
"nonattainment)" areas such as Bakersfield and Colton, California.
22
-------
APPENDIX A
PCB-CONTAHINATED SOIL TREATMENT IN A
TRANSPORTABLE CIRCULATING BED COMBUSTOR
(Paper present to the Hazardous Materials Management Conference
and Exposition at Anaheim, California, April 29 - May 1, 1986.)
-------
OGDEN
ENVIRONMENTAL SERVICES, INC,
PCB-CONTAMINATED SOIL
TREATMENT IN A TRANSPORTABLE
CIRCULATING BED COMBUSTOR
by
D. D. JENSEN
Staff Scientist
D. T. YOUNG
Manager, Combustion Projects
Presented at
Hazardous Materials Management
Conference and Exposition
Anaheim, California
April 29 - May 1. 1986
OES was formerly the Hazardous Waste Management Division
of GA Technologies Inc.
-------
PCS-CONTAMINATED SOIL TREATMENT IN A
TRANSPORTABLE CIRCULATING BED COMBUSTOR
by
D. D. Jensen, Ph. D. and D. T. Young
GA Technologies Inc.
San Diego, California
ABSTRACT
A trial burn of PCB-contaminated soils was
completed in GA Technologies' transportable
Circulating Bed Combustor (CBC). Over 4000
pounds of soil containing 1% PCB were treated
in three identical 4-hr runs at 1800°F. The re-
sults showed excellent compliance with U.S. En-
vironmental Protection Agency (EPA) Toxic
Substances Control Act (TSCA) requirements.
Destruction and removal efficiencies (DREs)
were greater than 99.9999% and PCB in com-
bustor ash was less than 200 ppb. No chlorinated
dioxins or furans were detected in the stack gas,
bed ash, or fly ash. In addition, no significant
concentrations of other Products of Incomplete
Combustion (PICs) were detected. Combustion
efficiencies were greater than 99.9%, with CO
concentrations less than 50 ppm and NOX con-
centrations less than 75 ppm. Particulate emis-
sions were generally below 0.08 grain/dscf and
HC1 emissions were maintained below 4.0 Ib/hr
by introducing limestone directly into the com-
bustor. These results led to the first TSCA per-
mit for a transportable incinerator which can
be used in all ten EPA regions. This demon-
strates that the CBC is an environmentally ac-
ceptable means of treating contaminated soil
containing PCB and other organic wastes. In
addition, the high thermal efficiency, the ab-
sence of afterburners or scrubbers, and the use
of simple feed systems make CBC treatment
competitive with soil removal and transport to
landfills and other potential treatment/disposal
options.
INTRODUCTION
Polychlorinated biphenyls, or PCBs, have
perhaps received more scrutiny than any other
hazardous chemicals found in waste sites around
the country. This group of 209 synthetic chlor-
inated organic compounds found wide use" as a
dielectric fluid in utility transformers and ca-
pacitors, and as a high-temperature heat trans-
fer medium (1). However, because of their ex-
ceptional resistance to degradation in the
biosphere and apparent toxicity, the manufac-
ture and sale of PCBs were banned in 1976 for
virtually all purposes. The control, treatment,
and disposal of PCBs was mandated by TSCA
and is currently handled through EPA's Office
of Toxic Substances.
Until recently, it has been common practice
to remove contaminated soils for burial in a se-
cured landfill. However, this option is becoming
less desirable as landfill costs escalate, the num-
ber of available landfill sites drop, and gener-
ators or potential responsible parties (PRPs)
become increasingly aware of retained liability
associated with the contaminated soils, even in
a secured landfill. Treatment of PCB-contami-
nated soil by incineration in the CBC can elim-
inate or significantly reduce the potential lia-
bility of generators or PRPs at a cost competitive
with landfill prices.
The use of CBC technology for hazardous
waste treatment builds on over 15 years expe-
rience at GA in the design, development, and
-------
operation of fluidized bed combustors. In 1980
GA and Ahlstrom of Finland formed Pyropower
Corp(2000°F).
TABLE 1
CIRCULATING BED TEST RESULTS
Waste
Form
Desctruction
Efficiency, %
HC1
Capture, %
Ca/Cl2
Ratio
Carbon Tetrachloride
Freon
Malathion
Dichlorobenzene
Aromatic Kitrile
Trichloroethane
Liquid
Liquid
Liquid
Sludge
Tacky solid
Liquid
99.9992
99.9995
> 99.9999
99.999
> 99.9999
99.9999
99.3
99.7
99
99
2.2
2.4
1.7
1.7
-------
COMBUSTOR
LIMESTONE
FEED
, FLUE GAS
-*- 1 XrnniPR
SOIL
FEED
FLUE GAS
(DUST)
FILTER
STACK
FD
COOLING
WATER
ASH
CONVEYOR
SYSTEM
Fig. 1. Schematic flow diagram of circulating bed combustor for soil treatment
TEST DESCRIPTION
A variety of requirements are imposed
prior to and during a PCB trial burn (2). The
key target of a trial burn is to ensure that PCB
DREs are > 99.9999% at the operating condi-
tions chosen for the incinerator. In addition, the
concentration of PCB in ash from the unit must
not exceed 2 ppm. The potential formation of
PICs is also carefully evaluated, with particular
attention given to polychlorinated dibenzo-p-
dioxins (PCDDs) and polychlorinated dibenzo-p-
furans (PCDFs). The combustion efficiency of
the unit must be >99.9% and particulate emis-
sion must not exceed 0.08 grain/dscf.
The CBC trial burn was carried out in GA's
transportable unit, shown in Figure 2. Soil
treated in the test was obtained from a former
chemical processing site known to contain pock-
ets of PCB up to 6000 ppm, as well as other
organic and inorganic wastes. In order to ensure
that the CBC would be permitted to treat all
likely site concentrations of PCB, uncontami-
nated soil from the site was "spiked" with liquid
PCB to 10,000 ppm. Spiking was carried out by
blending a 50:50 commercial mixture of PCB
"1248" and trichlorobenzene with a ribbon
blender in 1000 Ib lots. Approximately 4000 Ib
of soil was spiked for the three burns required
by the TSCA trial burn permit.
While the CBC was maintained at 1800T
using natural gas as the auxiliary fuel, several
barrels of clean site soil were introduced into
the CBC prior to the addition of spiked soil.
During this time all operating parameters and
system components were confirmed to be in the
required operating ranges. Process parameters
monitored included:
Temperature around the loop
Pressure drop across the loop
Soil feed rate
Primary air flow
Secondary air flow
Loop seal air flow
Total air flow
Methane flow
CO concentration
COo concentration
Excess oxygen level
concentration.
-------
Fig. 2. Transportable 16-inch circulating bed combu?tor
-------
Spiked soil was pneumatically transported
to a bunker and screw feeder. Soil feeding, lime-
stone addition, and stack gas monitoring were
started simultaneously. An EPA Modified
Method 5 sample train (3) was used to sample
stack gas emissions. In addition, a separate Vol-
atile Organic Sampling Train (VOSl) (4) was
used to sample for volatile organic PICs. Feed.
bed ash, and fly ash samples were also gathered
throughout the test (see Figure 1 for sample port
locations). Three identical tests of spiked soil
(4 hours each) were carried out over two days
in late May 1985. Each test was observed and/
or audited by EPA personnel or representatives.
All feed, ash, and stack gas samples were sub-
sequently analyzed for PCBs, PCDDs, and
PCDFs. Fly ash. bed ash. and stack gas samples
were also analyzed for other PICs (both volatile
and semivolatilei. Stack gases were analyzed for
fly ash and chloride release as well.
RESULTS
Table 2 presents a summary of the trial
burn operational data and test results gathered
during the tests. Near-identical conditions were
maintained for each of the tests. In each case
PCB DREs were well in excess of the EPA-re-
(juired 99.99997,. PCB concentration in the bed
ash and the fly ash did not exceed 200 ppb. No
PCDDs or PCDFs were detected in the stack gas,
bed ash, or fly ash. Combustion efficiencies were
TABLE 2
PCB TRIAL BURN OPERATIONAL DATA AND TEST RESULTS
Parameter
Test Duration, hr
Operating Temperature, °F
Soil Feed Rate, Ib/hr
Total Soil Feed, Ib
PCB Concentration in Feed,
ppm
DRE, 5,
PCB Concentration
Bed Ash, ppm
Fly Ash, ppm
Dioxin/Furan Concentration
Stack Gas, pp
Bed Ash, ppm
Fly Ash, ppm
Combustion Efficiency, %
Acid Gas Release, Ib/hr
Particulate Emissions,
grain/scf (dry)
Excess Oxygen, %
CO, ppm
C02, %
NOX, ppm
TSCA
Requirement
-4
> 99.9999
<2
<2
_
>99.9
<4.0
3.0
1
4
1800
328
1592
11,000
99.999995
0.0035
0.066
ND(a)
ND
ND
99.94
0.16
0.095(b)
7.9
35
6.2
26
Test Number
2
4
1800
412
1321
12,000
99.999981
0.033
0.0099
ND
ND
ND
99.95
0.58
0.043
6.8
28
6.0
25
3
4
1800
324
1711
9,800
99.999977
0.186
0.0032
ND
ND
ND
99.97
0.70
0.0024
6.8
22
7.5
76
(a'ND - Not detected.
(b)Derived from 2-hr makeup test.
-------
greater than 99.9^ and acid gas release was well
below the required 4 Ib/hr. Particulate emis-
sion? were generally less than the required O.OS
grain/d>cf. Only the grain loading from the first
test, obtained from a 2-hr makeup test after the
completion of Tests 1 through 3, showed a value
slightly higher than the limit. This is attributed
to off-normal process conditions for the bag-
house, i.e., excessive blowback air pressure along
with a higher-than-normal number of blowback
cycles. Nitrogen oxides and CO levels remained
low as a result of the staged combustion utilized
in the CBC and the relatively low combustion
temperature (1800°F). These results demon-
strate that the CBC is an effective mean? to
destroy PCBs contained in a soil matrix, without
the need for high temperatures, afterburners,
or wet scrubbers. In particular, the absence of
undesirable combustion byproducts helps en-
sure that effective treatment of soil can be ob-
tained in an environmentally acceptable manner.
These results confirm the design of GA's
transportable CBC shown in Figure 3. The com-
bustor and all other plant components are de-
signed as modular units which can be trans-
ported by truck or rail. These units are assembled
at the site into an operating unit in four to six
weeks. The major components of this CBC plant
include the combustor loop, feed system, and
pollution control and air induction equipment.
GA's 30-inch transportable CBC is capable of
processing up to 4 t/hr of dry soil on a 24-hour
basis, requiring an operating crew of only two
persons per shift. Soil treatment costs may bi'
as low as $100/ton for a large site. For smaller
site? or sites having unique treatment require-
ments, costs may approach "$400/ton.
STACK
COMBUSTION
CHAMBER
CYCLONE
INDUCED
DRAFT FAN
SOLIDS
FEED
FLUE GAS
COOLER
BAGHOUSE
FLY ASH
CONVEYOR
COMBUSTOR
ASH REMOVAL
FORCED
DRAFT
FAN
Fig. 3. Isometric of site-assemblied circulating bed combustor
-------
CONCLUSION
The results of the PCE soil trial burn in
GA's CBC demonstrated compliance with EPA
TSCA requirements. The CBC is now one of only
seven incinerators nationwide permitted to burn
PCB. and one of only two permitted transport-
able incinerators, the other being the EPA ro-
tary kiln. It i? the first transportable incinerator
to be permitted in all ten EPA regions. Stack
emissions from the CBC are well within regu-
latory requirement? and residual PCB in bed ash
and fly ash is well below regulatory require-
ments. The superior thermal efficiency, high
throughput, and small staffing requirements of
the CBC provide a soil treatment option that is
cost competitive with landfill disposal while at
the same time reducing overall liability of the
generator or PEP.
REFERENCES
1. SCS Engineers, Inc.. "PCB Disposal Man-
ual," Palo Alto. C.A: Electric Po\\er Research
Institute. Report No. CS-409S, June 19S.r>
2. 'Tolychlonnated Riphcnyls tPCBs' Manu-
facture. Processing. Distribution in Com-
merce and Use Prohibition," -10 CFK 701.To.
u. "Test Methods for Evaluating Solid Waste."
U.S. EPA Report SW-NJG, 2nd Edition, 1HS4.
4. "Proposed Sampling and Analytical Meth-
odologies for Addition to Test Methods for
Evaluating Solid Waste: Physical/Chemical
Methods (SW-84G. 2nd Edition)," U.S. EPA
Report PB55-103026, 19S4.
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