United States
Environmental Protection
Agency
Office of
Research and Development
Cincinnati, OH 45268
EPA540/R-94/514a
April 1995
EPA S/TE Technology Capsule
Texaco Gasification
Process
Introduction
In 1980, the U.S. Congress passed the Comprehensive
Environmental Response, Compensation, and Liability Act
(CERCLA), also known as Superfund. to protect human health
and the environment from uncontrolled hazardous waste sites.
CERCLA was amended by the Superfund Amendments and
Reauthorization Act (SARA) in 1986-amendments that em-
phasize the achievement of long-term effectiveness and per-
manence of remedies at Superfund sites. SARA mandates
implementing permanent solutions and using alternative treat-
ment technologies or resource recovery technologies, to the
maximum extent possible, to clean up hazardous waste sites.
State and federal agencies, as well as private parties, are
now exploring a number of innovative technologies for treating
hazardous wastes. The sites on the National Priorities List
total over 1,200 and comprise a broad spectrum of physical,
chemical, and environmental conditions requiring various types
of remediation. The U.S. Environmental Protection Agency
(EPA) has focused on policy, technical, and informational
issues related to exploring and applying new remediation
technologies for Superfund sites. EPA's Superfund Innovative
Technology Evaluation (SITE) Program addresses these is-
sues. The SITE Program was established to accelerate devel-
opment, demonstration, and use of innovative technologies
for site cleanups. EPA SITE Technology Capsules summarize
the latest information available on selected innovative treat-
ment and site remediation technologies. These Capsules are
designed to help EPA remedial project managers, EPA on-
scene coordinators, contractors, and other site cleanup man-
agers understand the types of data and site characteristics
needed to effectively evaluate a technology's applicability to
their site.
In treating hazardous wastes, the Texaco Gasification
Process (TGP) is an innovative extension of Texaco's con-
ventional fuels gasification technology. According to Texaco,
the TGP is capable of processing hazardous waste materials
containing both organic compounds and heavy metal contami-
nants. The organics are converted into a synthesis gas
(syngas)-a usable fuel or chemical intermediate-composed
mainly of hydrogen and carbon monoxide. Most heavy metals
mix with the residual mineral matter in the waste matrix and
solidify into a glassy slag.
The TGP was evaluated under the EPA's SITE Program
in January 1994 at Texaco's Montebello Research Laboratory
(MRL) in South El Monte, CA, located in the greater Los
Angeles area. The Demonstration used a soil feed mixture
consisting of approximately 20 weight-percent waste soil from
the Purity Oil Sales Superfund Site, Fresno, California and 80
weight-percent clean soil. The mixture was gasified as a
slurry in water. The slurry also included coal as a support fuel
and was spiked with lead and barium compounds (inorganic
heavy metals) and chlorobenzene (volatile organic compound)
as the Principal Organic Hazardous Constituent (POHC). In-
formation on the TGP and results of the SITE Demonstration
at the Texaco MRL are provided here.
Abstract
The TGP is a commercial gasification process which
converts organic materials into syngas, a mixture of hydrogen
and carbon monoxide. The feed reacts with a limited amount
of oxygen (partial oxidation) in a refractory-lined reactor at
temperatures between 2,200° and 2,650°F* and at pressures
above 250 pounds per square inch gauge (psig).
According to Texaco, these severe conditions destroy
hydrocarbons and organics in the feed and avoid the forma-
tion of undesirable organic by-products associated with other
fossil fuel conversion processes. At such high operating tem-
peratures, the residual ash melts-forming an inert glass-like
slag.
Texaco reports that the syngas can be processed into
high-purity hydrogen, ammonia, methanol, and other chemi-
cals, as well as clean fuel for electric power.
. A list of conversion factors is included at the end of the te:
SVPERFim INNOVATIVE
TECHNOLOGY EVALUATION I
Printed on Recycled Paper
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The SITE Program evaluated the TCP's ability to treat
hazardous waste materials containing both organic compounds
and inorganic heavy metals. The primary technical objectives
of the demonstration were to determine the TCP's ability to:
Produce a usable syngas product;
Achieve 99.99 percent Destruction and Removal Efficiencies
(DREs) for organic compounds; and
Produce a non-hazardous primary solid residual-coarse
slag-and secondary solid residuals-fine slag and clarifier
bottoms.
Additionally, the demonstration test results and observa-
tions were evaluated to:
. Develop overall capital and operating cost data; and
. Assess the reliability and efficiency of the TGP operations.
The findings of the TGP SITE Demonstration are as fol-
lows:
. The TGP produced a syngas that can be used as feed for
chemical synthesis facilities or as a clean fuel for the produc-
tion of electrical power when combusted in a gas turbine. The
average composition of the dry synthesis gas product con-
sisted of 37% hydrogen, 39% carbon monoxide and 21%
carbon dioxide. No organic contaminants, other than meth-
ane (55 ppm), exceeded 0.1 ppm. The average heating value
of the gas, a readily combustible fuel, was 239 British thermal
units (Btu) per dry standard cubic foot (dscf).
. The ORE for the designated POHC (chlorobenzene) was
greater than the 99.99% goal.
. The average Toxicity Characteristic Leaching Procedure
(TCLP) measurement for the coarse slag was lower than the
regulatory levels for lead (5 milligrams per liter) (mg/L) and:
barium (100 mg/L). The average California Waste Extraction
Test (WET)-Soluble Threshold Limit Concentration (STLC)
measurement for the coarse slag was lower than regulatory
value for barium (100 mg/L) and higher than the regulatory
value for lead (5 mg/L).
. Volatile heavy metals, such as lead, tend to partition and
concentrate in the secondary TGP solid products-fine slag
and clarifier solids. The average TCLP and WET-STLC
measurements for these secondary TGP solid products were
higher than the regulatory limits for lead, but lower than the
regulatory limits for barium.
. Texaco estimates an overall treatment cost of $308 per ton
of soil for a proposed transportable unit designed to process
100 tons per day (tpd) of soil with characteristics similar to
that from the Purity Oil Sales Superfund Site, based on a
value of $1.00/million Btu for the syngas product. Texaco
estimates an overall treatment cost of $225 per ton of soil for
a proposed stationary unit designed to process at a central
site, 200 tpd of soil with characteristics similar to that from the
Purity Oil Sales Superfund Site, based on a value of $2.00/
million Btu for the syngas product.
- In continuous operations, proposed commercial units are
expected to operate at on-stream efficiencies of 70% to 80%
to allow for scheduled maintenance and intermittent, un-
scheduled shutdowns.
The TGP technology evaluation applied the EPA's stan-
dard nine criteria from the Superfund feasibility study (FS)
process. Summary conclusions appear in Table 1.
Technology Description
Texaco maintains three pilot-scale gasification units, ancil-
lary units, and miscellaneous equipment at the Montebello
Research Laboratory (MRL), where the SITE demonstration
was conducted. Each gasification unit can process a nominal
throughput of 25 tpd of coal. The SITE Demonstration em-
ployed one of the three pilot-scale gasification units, the High
Pressure Solids Gasification Unit II (HPSGU II), and support
units as shown on the Figure 1 block flow diagram. The
diagram identifies the key MRL process units that are part of
the overall facility.
Solids Grinding and Slurry Preparation Unit
The slurry feed used in the demonstration was a blend of
the Purity Oil soil slurry and a clean soil slurry. Coal and clean
soil were precrushed in a hammer mill. For each slurry, the
precrushed product (coal and clean soil; site-screened Purity
Oil waste soil and coal) was combined with water, an ash
fluxing agent, and a slurry viscosity reducing agent in a rod
mill, where the mixture was ground and slurried. The mill
product was screened to remove oversize material and trans-
ferred to the HPSGU II slurry storage tanks where the inor-
ganic spikes (lead and barium) were added.
High Pressure Solids Gasification Unit II
The slurry was gasified in MRL's HPSGU II. This unit
includes equipment for slurry feeding, gasification, gas scrub-
bing, slag removal, clarifier solids removal, and process water
handling. Figure 2 is primarily a schematic flow diagram of the
process equipment and flows within the HPSGU II used in this
demonstration. Secondarily, Figure 2 defines the interaction of
the HPSGU II process streams with other MRL TGP process
streams and units.
During the demonstration, the slurry was spiked with chlor-
obenzene as it was pumped into the gasifier. The gasifier is a
two-compartment vessel, consisting of an upper refractory-
lined reaction chamber and a lower quench chamber. Oxygen
and slurry feeds were charged through an injector nozzle into
the reaction chamber where they reacted under highly reduc-
ing conditions to produce raw syngas and molten slag. The
oxygen-to-slurry ratio was controlled to maintain an operating
temperature sufficient to convert the soil and coal ash into a
molten slag. The average pressure was 500 psig.
From the reaction chamber, the raw syngas and molten
slag flowed into the quench chamber, where water cooled and
partially scrubbed the raw syngas. The raw syngas leaving the
gasifier quench chamber was then further scrubbed of hydro-
gen chloride and particulates with additional water, cooled to
near ambient temperature, and routed to MRL's Acid Gas
Removal Unit. More than 99% of the chlorides in the syngas
were transferred to the circulating water in these steps.
The water quench also converted the molten ash into
glass-like slag particles, which then passed down through the
quench chamber/lockhopper system. The lockhopper system
discharged the slag solids to a shaker screen which separated
the slag into a coarse fraction (coarse slag), and a fine fraction
(fine slag). The fine slag was recovered using a vacuum belt
filter. The filtrate from the vacuum belt filter was recycled to the
lockhopper system.
Water from the quenching and scrubbing steps was com-
bined and cooled. Solids in the combined stream were re-
moved using a clarifier, which produced an underflow stream
of concentrated solids and water, called clarifier bottoms, and
an overflow stream of clarified water. Periodically, the clarifier
bottoms were drawn off and filtered to produce clarifier solids
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Table 1. Evaluation Criteria for the Texaco Gasification Process Technology
Evaluation Criteria for Technology
Overall protection
of human health
and the enveronment
Compliance with
ARARS*
Long-term
effectiveness
and
permanence
Reduction of toxicity,
mobility, or volume
through treatment
Short-term
effectiveness
Implementability
Cost"
Community
acceptance
State
acceptance
• Provides both short- and long-term protection by eliminating exposure to both organic and inorganic contaminants in soil.
. Prevents further groundwater contamination and offsite migration by destroying organic contaminants and demonstrating
a potential to immobilize heavy metals into a non-leaching glassy, coarse slag.
1 Requires measures to protect workers and community during excavation, handling, and treatment.
1 Requires compliance with Resource Conservation and Recovery Act (RCRA) treatment, storage, and land disposal Federal
regulations (of a hazardous waste).
, Excavation and construction and operation of onsite treatment unit may require compliance with location-specific ARARs.
. Emission controls are needed to ensure compliance with air quality standards, if volatile compounds and particulate
emissions occur during excavation, handling, and treatment prior to slurrying.
, Wastewater discharge to treatment facilities or surface water bodies requires compliance with Clean Water Act
regulations.
• CERCLA defines drinking water standards established under the Safe Drinking Water Act that apply to remediation of
Superfund sites.
, Requires compliance with Toxic Substances Control Act treatment and disposal regulations for wastes containing
polychlorinated biphenyls.
, CERCLA remedial actions and RCRA corrective actions are to be performed in accordance with Occupational Safety and
Health Administration requirements.
, Effectively destroys organic contaminants and demonstrates a potential to immobilize inorganic heavy metals into a
non-leaching glassy coarse slag.
. Site contaminants are destroyed or removed with residuals.
, The potential immobilization of heavy metals into non-leaching glassy, coarse slag requires further testing for anticipated
long-term stability.
. Fine slag and clarifier solids may require further treatment, particularly when volatile heavy metals are present.
, Wastewaters require further treatment to effect long-term stability of contaminants and reuse of water.
• Effectively destroys toxic organic contaminants and demonstrates a potential to immobilize inorganic heavy metals into
the primary solid product, a non-leaching glassy coarse slag.
. Reduction of soil to glassy slag reduces overall volume of material.
• Emissions and noise controls are required to eliminate potential short-term risks to workers and community from noise
exposure and exposure to contaminants and particulate emissions released to air during excavation, handling, and
treatment prior to slurrying.
. Treatability testing required for wastes containing heavy metals.
• Large process area required.
. Large-scale transportable 100 tpd unit on multiple transportable skids requires large scale remediation with onsite
commitment of more than 50,000 tons of soil and 2 years of operation.
' Initial transportable unit can be constructed and may be available in 24 months.
• Large size of unit and ex-situ thermal destruction basis for unit may provide delays in approvals and permits.
. Large-scale, complex, high-temperature, high-pressure, transportable thermal destruction unit at approximately $308 per
ton of waste soil.
. Large-scale, ex-situ, high-temperature, high-pressure, thermal destruction unit may require significant effort to develop
community acceptance.
. If remediation is conducted as part of RCRA corrective actions, state regulatory agencies may require operating permits,
such as: a permit to operate the treatment system, an air emissions permit, and a permit to store contaminated soil for
greater than 90 days.
* Applicable or relevant and appropriate requirements.
** Actual cost of a remediation technology is highly site-specific and dependent on matrix characteristics. See Overall Unit Cost section of this
Capsule. A complete cost and economic analysis can be found in the Innovative Technology Evaluation Report.
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Coal
Inorganic
spike
Soil
Water
4 4
.. ,
Make-up
water
preparation
flaw pas
(syngas)
solids
gasification unit
To disposal
Organ fc spike
^C o a r s e slag
^ Fine slag
^ .Clarifier solids
1
^ Vacuum filtrate/ 1
process wastewater m
Wastewater
treatment
To disposal -^-
Filter cake
>«c/doas
Neutralized
Effluent water
Caustic/
gc/c/
Fuel a as
Absorber off-cas
OMzeroff-oas
To sewer
Figure 1. Block flow diagram of MRL TGP during SITE demonstration.
Oxygen
Organic spike
Water -—»4J
Coal/Soil —**•[ slurry preparation j
Inorganic spike
Coridensate from gas cooling ,.
J Gas co
l^ac/d gas
removal
Flash gas I
, ^
Sulfur
removal I
Makeup water
_ _.Wa|§£ i _ JWa§!fW!!iL.
fi'teig, ,»J Storage
nr^"
LJ!
Clarifier
solids
Figure 2. Schematic flow diagram of MRL's HPSGU II during SITE demonstration.
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cake and vacuum filtrate. The clarifier overhead flowed to the
flash tank where it combined with the condensate from the
cooling of the raw syngas. In the flash tank, dissolved gases
are removed from the water at low pressure (flash gas). Except
for a small wastewater blowdow stream, the flash tank water
was recycled to the gasifier quench chamber and raw gas
scrubber.
The wastewater blowdown and vacuum filtrate were routed
to temporary storage for testing prior to treatment and disposal.
Acid Gas Removal/Sulfur Removal
During the demonstration, MRL used a regenerate sol-
vent process to separate hydrogen sulfide and carbonyl sulfide
from the raw syngas. The raw syngas was contacted with the
solvent, which removed the hydrogen sulfide, carbonyl sulfide,
and some carbon dioxide (acid gases) producing a low-sulfur-
content combustible fuel gas. The fuel gas was then flared.
The acid gases stripped from the solvent and combined with
the gasification system flash gas were fed to the Sulfur Re-
moval Unit where the sulfides were absorbed using a caustic
solution. The dissolved sulfides were oxidized with air and
steam, producing a solution of sodium thiosulfate that was
neutralized and routed to wastewater treatment.
As with the fuel gas stream, the Sulfur Removal Unit
absorber and oxidizer off-gas streams were flared.
Technology Applicability
The versatile TGP can process a variety of waste streams.
Virtually any carbonaceous hazardous or non-hazardous waste
stream can be processed in the TGP as long as adequate
facilities are provided for pretreatment and storage.
Depending upon the physical and chemical composition of
the waste stream, it can either be used as the primary feed to
the gasifier or it can be co-gasified with a high-Btu fuel such as
coal, petroleum coke, or oil. The combined feed must be
slurried successfully, high enough in heating value to maintain
gasifier temperatures, and composed of an ash matrix with a
fusion temperature that falls within operational limits.
In general, the ratio of waste feed to fuel can be adjusted
over a wide range. Although a waste stream can be used as
the sole feed to the gasifier, blending the waste with another
feed can ensure continuity and stability of operation.
The TGP can treat wastes that fall into three categories,
(1) Solid or liquid wastes that contain sufficient energy to
sustain gasifier operation as the sole feed without adding
another higher-heating-value fuel.
(2) Solid wastes with heating values too low to sustain gasifier
operation that can be supplemented with a higher-heating-
value fuel, such as coal.
(3) Liquid waste with insufficient heating values that can be
combined with a higher-heating-value fuel. In this case the
liquid waste can be used as the fluid phase of the primary
feed slurry.
The TGP has operated commercially for nearly 45 years
on feeds such as natural gas and coal, and non-hazardous
wastes such as liquid petroleum fractions, and petroleum coke.
Texaco's gasification process is currently licensed in the U.S.
and abroad. The syngas is used for the production of electric
power and numerous chemical products, such as ammonia,
methanol, and high-purity hydrogen. As an innovative process
gasifying less traditional and hazardous wastes, Texaco re-
ports that the TGP has processed various waste matrices
containing a broad range of hydrocarbon compounds including
coal liquefaction residues, California hazardous waste material
from an oil production field (petroleum production tank bot-
toms), municipal sewage sludge, waste oil, used automobile
tires, waste plastics, and low-Btu soil. Texaco licensees in
Europe have had long-term success in gasifying small quanti-
ties of hazardous waste as supplemental feedstock including
PCBs, chlorinated hydrocarbons, styrene distillation bottoms,
and waste motor oil.
Texaco expects to design TGP facilities with flexible and
comprehensive storage and pretreatment systems capable of
processing a wide range of waste matrices slurried with coal or
oil, water, and additives. If the specific waste exhibits unusual
physical or chemical characteristics that would affect the ability
of the pretreatment module to slurry the feed, additional pre-
treatment equipment may supplement the existing design.
Technology Limitations
The TGP can process all waste stream matrices based on
the availability of adequate materials-handling, pretreatment,
and slurrying equipment. The unit's complexity and costs, and
the economic benefit of a tie-in to its syngas product, mandate
that on-site remediations be limited to relatively large sites with
a minimum of approximately 50,000 tons of waste feed and
about two years of operation.
Process Residuals
Solid TGP products such as coarse slag, fine slag, and
clarifier solids are stored and characterized to allow proper
disposal based on their hazardous or non-hazardous charac-
teristics. In most cases, any excess water residuals will be
treated by conventional wastewater treatment technologies.
TGP Support Requirements
The TGP support requirements include site conditions
(surface, subsurface, clearance, area, topography, climate, and
geography), utilities, facilities, and equipment.
For a proposed 100-tpd transportable unit, surface re-
quirements would include a level, graded area capable of
supporting the equipment and the structures housing it. The
complexity and mechanical structure of a high-temperature,
high-pressure TGP unit mandate a level and stable location.
The unit cannot be deployed in areas where fragile geologic
formations could be disturbed by heavy loads or vibrational
stress. Foundations must support the weight of the gasifier
system, which is estimated at 50 tons, as well as other TGP
support facilities and equipment. The transportable TGP unit
would weigh approximately 300 tons and consist of multiple
skid-mounted trailers requiring stable access roads that can
accommodate oversized and heavy equipment.
The transportable 100-tpd TGP unit would require an area
of approximately 40,000 square feet (ft2) (275 ft x 150 ft), with
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height clearances of up to 70 ft. This area should accommo-
date all TGP process operations, although additional space
could be needed for special feed preparation and waste residu-
als storage facilities.
The transportable TGP unit could be used in a broad
range of different climates. Although prolonged periods of freez-
ing temperatures might interfere with soil excavation and han-
dling, coal handling, slurry preparation, and water-related
operations, they would not affect a TGP design that incorpo-
rates adequate heating, insulating, and heat-tracing capabili-
ties at critical locations.
The proposed transportable 100-tpd TGP unit would re-
quire the following utilities: 91 tpd of oxygen, 39 tpd of coal, 5
tpd of lime, 410 kilowatthours per hour (kWh/h) of electrical
power, 40 gallons per minute (gpm) of make-up water, and
less than 1 tpd of nitrogen.
Support facilities would include staging areas for contami-
nated soil and coal prior to pretreatment, materials-handling,
and slurry preparation. Syngas product would be routed by
pipeline directly off-site without any support facilities for stor-
age or transport. Solid products would be stored in roll-off bins.
Wastewater would be collected in appropriate tank storage. All
support facilities must be designed to control run-off and fugi-
tive emissions. Support equipment would include excavation/
transport equipment such as backhoes, front-end loaders, dump
trucks, roll-off bins, and storage tanks.
Performance Data
To assess the TGP operation and its ability to process a
RCRA-designated hazardous waste feed that does not comply
with TCLP and WET-STLC regulatory limits, non-RCRA haz-.
ardous soil from the Purity Oil Sales Superfund Site in Fresno,
CA was spiked with lead nitrate and barium nitrate during
slurry preparation to create a surrogate RCRA-hazardous waste
feed. For the extended SITE demonstration, additional slurry
was required and prepared using a mixture of clean soil and oil
spiked with barium nitrate since further supplies of Purity Oil
soil could not be obtained. To ensure a sufficient concentration
of the designated POHC for ORE determination, chloroben-
zene was added to the Purity Oil/clean soil mixed test slurry at
the slurry feed line to the gasifier. Table 2 shows the overall
composition of the mixed, spiked test slurry processed during
the TGP SITE Demonstration.
Three runs were conducted over a 2-day period, treating
approximately 40 tons of slurry. The total amount of slurry
treated during the entire demonstration (scoping runs, initial
shakedown, system startup, a pretest run, the three replicate
runs, and post-demonstration processing of the slurry inven-
tory) was approximately 100 tons. Critical process parameters
included slurry feed rate; raw syngas, flash gas, and fuel gas
flow rates; make-up and effluent water flow rates (except neu-
tralized wastewater); weight of coarse slag, fine slag, and
clarifier solids; and the organic spike flow rate. Critical chemi-
cal/analytical parameters included VOCs, polychlorinated
dibenzodioxins (PCDDs), polychlorinated dibenzofurans
(PCDFs). and metals in all feed and discharge streams (except
neutralized wastewater); TCLP and WET-STLC analyses on
waste feed, slurry feed, coarse slag, fine slag, and clarifier
solids; and compositions of process gas streams.
Table 2. Composition of Demonstration Slurry Feed
Slurry, pounds (Ib)
Purity Oil soil Clean soil
Total mixed*
Pittsburgh #8 coal
Hovoline SAE 30 oil
LA. County soil
Fresno County soil
Purity Oil soil
Water
Gypsum
Surfactant
Barium nitrate
Lead nitrate
TOTAL
10,511
—
—
—
5,264
10,529
—
21
330
145
26,800
56,280
2,050
11,000
11,080
—
54,000
2,500
130
1,000
—
138,040
66,791
2,050
11,000
11,080
5,264
64,529
2,500
151
1,330
145
164,840
. The total slurry feed does not include the chlorobenzene organic
spike (L-5) that was added (at approximately 3,150 milligrams per
kilogram (mg/kg) based on slurry flow) to the total mixed slurry flow
to the gasifier at 6.20, 6.30, and 6.75 pounds per hour (Ib/h) for
Runs 1, 2, and 3, respectively.
Note.-A list of conversion factors is included at the end of the text.
ORE
The ORE was the measure of organic destruction during
the demonstration test. This parameter is determined by ana-
lyzing the concentration of the POHC in the feed slurry and the
effluent gas stream(s). For a given POHC, ORE is defined as
follows:
ORE =
x 100%
Where:
WIN = Mass feed rate of the POHC of interest in the waste
stream feed
WOUT - Mass emission rate of the same POHC present in the
effluent gas streams prior to release to the flare.
For these TGP SITE tests, DREs were calculated in two
ways. For the gasification process, the effluent gas streams
included the raw syngas and flash gas; for the overall TGP
operation, the effluent gas streams included the fuel gas, the
absorber off-gas, and oxidizer off-gas. The POHC identified for
the demonstration was chlorobenzene. This compound was
selected as a representative stable compound for the purpose
of evaluating the TCP's ability to destroy organic compounds.
As shown in Table 3, all calculated DREs were greater than
99.99 percent for chlorobenzene.
Slag and Solid Residuals Leachability
Test Slurry Leaching Characteristics
The test slurry was spiked with lead nitrate and barium
nitrate to create a surrogate RCRA-hazardous waste feed and
to evaluate the TCP's ability to produce a non-hazardous solid
residual in which heavy metals are bound in an inert slag
resulting in TCLP and WET-STLC measurements that are
lower than their respective regulatory limits. Table 4 shows that
the test slurry feed measurements were higher than the TCLP
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Table 3. Destruction and Removal Efficiencies (DREs) for Principal Organic Hazardous Constituent (POHC) - Chlorobenzene
ORE for gasification process
Run
1
2
3
Average
W'
(Ib/h)
6.20
6.30
6.75
6.42
Raw syngass
(Ib/h)
0.00016
0.00019
0.00023
0.00019
Flash gas
(Ib/h)
0.000013
0.000010
0.000014
0.000012
Total W * * .
(Ib/h)™*
0.000173
0.000200
0.000244
0.000210
ORE"""
(%)
99.9972
99.9966
99.9964
99.9967
ORE for overall Texaco MRL operation
Run
\
2
3
Average
(Ib/h)
6.20
6.30
6.75
6.42
Fuel gas
(Ib/h)
0.0000033
0.0000620
0.0000 130
0.0000250
Ate offgas
f/i/ftj
0.00010
0.00038
0.00023
0.00024
Oxid. offgass
<0.000019
0.000078
0.000011
<0.000016
Total W "
(Ib/h)
<0.000 122
0.000460
0.000254
<0. 00028 1
ORE**
>99.9980
99.9926
99.9962
>99.9956
= Mass feed rate of Chlorobenzene (POHC) in the waste stream feed.
T = M ass emission rate of Chlorobenzene (POHC) in gas effluent streams.
DRE=
x100
Note -A list of conversion factors is included at the end of the text.
Table 4. TCLP and WET-STLC Results - Lead and Barium
TCLP Pb
mg/L
WET-STLC Pb
mg/L
Range
Average
Range
Average
Regulatory value
Purity Oil soil*
Clean soil (S- 1)**
Slurry (SL- 1)***
Coarse slag (S-3)
Fine slag (S-4)
Clarifier solids (S-5)
8.1-8.4
3.3-5.8
11-18.3
691-1,330
5.0
223
<0.03
TCLP Ba
mg/L
8.3
4.5
14.9
953
54-6 1
6.7-11.1
22.8-52.9
903- 1,490
5.0
—
<0.5
WET-STLC Ba
mg/L
56
9.8
43.0
1,167
Range
Average
Range
Average
Regulatory value
Purity Oil soil*
Clean soil (S- 1)**
Slurry (SL- 1)*™
Coarse slag (S-3)
Fine slag (S-4)
Clarifier solids (S-5)
100
329
0.3
0.1-0.2
0.5-0.8
1.2-2.0
1.2-3.8
0.1
0.6
1.75
2.7
100
<5.0
<5.0-6.5
<5.0
5.6- 10.4
14-51.4
<5.5
<5.0
9.3
38.4
* Lead TCLP of Purity Oil soil (waste feed to produce Purity oil slurry with 15,000 mg/kg (as elemental lead) lead nitrate spike and barium TCLP
„ of Purity Oil soil with 30,000 mg/kg (as elemental barium) barium nitrate spike-measured in pretest spike study.
Clean soil is soil matrix used to produce clean soil slurry.
*** The SITE Demonstration slurry (SL-1) is a mixture of lead nitrate and barium nitrate-spiked slurries produced using Purity Oil soil and clean soil.
SL- 1 is composed of 26,800 Ib ofPurity Oil slurry mixed with 138,040 Ib of clean soil slurry (See Table 2.).
Note._ A list of conversion factors is included at the end of the text
Pb: Lead
Ba: Barium
-------
and WET-STLC regulatory limits for lead but lower than the
regulatory limits for barium.
Normalized TCLP and WET-STLC Values for Lead
in Test Slurry
The test soil composed of approximately 20 weight-per-
cent Purity Oil soil (lead TCLP of Purity Oil soil: 223 mg/L) and
80 weight-percent clean soil (lead TCLP of clean soil: <0.03
mg/L), could be expected to have a normalized, or corrected,
TCLP value for lead of approximately 40 mg/L. The test slurry,
composed of approximately 20 weight-percent total soil (nor-
malized TCLP value for lead: 40 mg/L) diluted by the remaining
slurry solution of 80 weight-percent coal, gypsum, and water
(no lead TCLP value) could be expected to have a calculated
TCLP value for lead of around 8 mg/L, which closely approxi-
mates the average TCLP measurement of 8.3 mg/L lead for
the test slurry. Similarly, an expected normalized WET-STLC
value of 280 mg/L lead, based on spiked soil blending, would
be consistent with the average WET-STLC measurement of 56
mg/L lead for the test slurry, due to the dilution of the coal,
gypsum, and water.
Fate of Barium in Test Slurry
The fate of the barium contaminant indicates that signifi-
cant changes occurred in the barium chemistry during slurry
formulation. A pretest study TCLP value of 329 mg/L was
measured in a leachate produced from the spiked Purity Oil
soil. This contrasts with the much lower 0.1 mg/L measured in
the TCLP leachate from the test slurry matrix, which included
coal, gypsum, and water. The introduction of sulfur-containing
gypsum and coal could have provided an environment in the
slurry that changed the original soluble barium nitrate spike
material to insoluble barium sulfate. The relative solubilities of
barium nitrate and barium sulfate differ by ten-thousand fold.
Since barium sulfate is relatively insoluble, it remains with the
solids and does not transfer to the leachate during the TCLP
test. The one thousand times reduction in the test slurry TCLP
result for barium from the pretest level in the Purity Oil soil
would be consistent with a partial speciation change to barium
sulfate.
SITE Demonstration Results
The SITE Demonstration showed that the mobility of the
lead in the main residual solid product-the coarse slag-was
lower than the mobility of the lead in the contaminated/spiked
soil. The mobility of the barium essentially remained unchanged.
The average TCLP and WET-STLC measurements for coarse
slag, which comprised 62.5 weight-percent of the total solid
residuals, were lower than the TCLP regulatory levels for lead
and barium and the WET-STLC regulatory value for barium.
The average TCLP and WET-STLC measurements for fine
slag, which constituted 35.9 weight-percent of the total solid
residuals, and clarifier solids, which amounted to 1.6 weight-
percent, were higher than the TCLP and WET-STLC regulatory
limits for lead but lower than the tests' regulatory limit for
barium. The leach test results indicated mixed success in
meeting the test objectives. Analysis of the effects of dilution
by the non-contributing slurry components-coal, water, gyp-
sum-on the TCLP and WET-STLC test results showed that
the TGP can potentially produce-as its major solid residual-
a coarse slag product with TCLP and WET-STLC measure-
ments below regulatory limits. The TGP effectively treated a
soil matrix exhibiting a normalized TCLP value of 40 mg/L for
lead and produced a coarse slag with an average TCLP value
of 4.5 mg/L lead and a fine slag with an average TCLP value of
14.9 mg/L lead.
The average WET-STLC measurements for all solid re-
sidual streams were higher than the WET-STLC regulatory
values for lead. However, the TGP demonstrated significant
improvement in reducing lead mobility as measured by WET-
STLC results. The process treated a soil matrix exhibiting a
normalized WET-STLC value of 280 mg/L for lead and pro-
duced a coarse slag with an average WET-STLC value of 9.8
mg/L lead and a fine slag with an average WET-STLC of 43
mg/L lead.
Synthesis Gas Product Composition
The synthesis gas (syngas) product from the TGP is com-
posed primarily of hydrogen, carbon monoxide, and carbon
dioxide. For a commercial unit, the raw syngas would receive
further treatment in an acid gas treatment system to remove
hydrogen sulfide. This would produce a combustible fuel gas
that could be burned directly in a gas-turbine/electrical-genera-
tion facility or be synthesized into other chemicals.
The raw gas from the gasifier was sampled and analyzed
to evaluate the TCP's ability to gasify a slurry containing a
RCRA-hazardous waste material and produce a synthesis gas
product. This gas stream was then treated in the MRL Acid
Gas Removal System; the resulting fuel gas product was
flared. Table 5 shows the compositions of the raw syngas and
the fuel gas product.
Products of Incomplete Reaction (PIRs)
The TGP is a gasification process which converts organic
materials into syngas by reacting the feed with a limited amount
of oxygen (partial oxidation). In addition to the syngas mixture
of hydrogen and carbon monoxide, other organic compounds
appear as products of the incomplete partial oxidation reaction.
The term "PIR" describes the organic compounds detected in
the gas product streams as a result of the incomplete reaction
process.
All gas streams, including the raw gas, flash gas from the
gasification section, fuel gas, absorber off-gas, and oxidizer
off-gas, contained trace amounts of volatile and semivolatile
PIRs. Carbon disulfide, benzene, toluene, naphthalene, naph-
thalene derivatives, and acenaphthene concentrations were
measured in the gas streams at parts per billion (ppb) levels.
The POHC-chlorobenzene-was also detected. Small amounts
of methylene chloride and phthalates were also detected but
likely were sampling and analytical contaminants. Measured
concentrations of PCDDs and PCDFs in the gas streams were
comparable to the blanks, indicating that these species, if
present, were at concentrations less than or equal to the
method detection limits (parts per quadrillion). Other com-
pounds such as xylenes, chloromethane, bromomethane,
dibenzofuran, fluorene, and phenanthrene (expected from the
thermal treatment of coal and chlorobenzene) were detected at
lower concentrations in the flash gas and off-gases.
Particulate Emissions
During the SITE demonstration, particulate emissions were
measured for the raw syngas and fuel gas streams. These
averaged 6.1 milligrams per cubic meter (mg/m3) in the raw
syngas, and 1.3 mg/m3 in the fuel gas. By comparison, the
-------
Table 5. Synthesis Gas Composition
Raw syngas composition and heating value
Run
2 ,
3
Average
«f
(vol. %)
34.6
26.9
35.4
32.3
CO
(vol.%)
330 3(3
39.6
34.6
CO,
(vol. %)
25.S 26.S
26.2
26.3
CH4
(ppmv)
87
51
42
60
N2
(vol. %)
5.1
5.7
5.8
Ar
(vol. %)
n T
0.0
0.05
0.1
cos
(ppm v)
120
170
130
140
H2S
(ppmv)
1,180
3,050
1,980
2,070
THC
(ppmv)
49
17
14
27
Heating
Value
(Btu/dscf)
219
210
228
219
Fuel gas composition and heating value
Run
",
(vol. %)
1 376
2 363
3 34.7
Average 36.9
Note.-
Hf-
CO:
C0r
A list of conversion
Hydrogen
Carbon monoxide
Carbon dioxide
CO
(vol. %)
39.1
35.0
41.3
38.5
factors
C°l
(vol. %)
21.0
20.9
21.2
21.0
is included at the
CHt: Methane
N,: Nitrogen
Ar: Argon
CH4
(Ppmv)
71
49
44
55
end of the text
N,
(vol. %)
4.9
5.6
54
COS:
HLS:
THC:
Ar
(vol. %)
0.2
0.05
0.1
0.1
cos
(ppmv)
33
44
50
42
Carbonyl sulf/de
Hydrogen sulf/de
Total hydrocarbons (excluding
H,S
(ppmv)
490
580
68
360
methane)
THC
(ppmv)
32
16
15
21
Heating
value
(Btu/dscf)
239
239
239
239
particulate emission standards for boilers and industrial fur-
naces processing hazardous waste (40 CFR Part 266 Subpart
H), and industrial, commercial, and institutional steam genera-
tors processing coal and other fuels (40 CFR Part 60 Subpart
Db) are higher than the average measured values for these
gas streams. Since the fuel gas product would not be vented or
flared in a commercial unit, but would be burned directly in a
gas-turbine/electrical-generation facility or synthesized into other
chemicals, it is expected that the treated vent gas from any of
these downstream facilities will be treated to meet applicable
particulate emissions standards. This must be assessed on a
case-by-case basis.
Acid Gas Removal
Hydrogen chloride gaseous emission rates measured from
0.0046 to 0.0117 Ib/h. The chlorine concentration in the feed
slurry, based on a chlorobenzene spike addition equivalent to
3,150 mg/kg in the slurry and the chloride concentration in the
slurry, ranged from 4.3 to 4.7 Ib/h. Using these figures, the
TCP's hydrogen chloride removal efficiency exceeded 99 per-
cent.
Sulfur-containing gas emission rates measured from 2.2 to
2.7 Ib/h. The sulfur concentration in the slurry, based on the
ultimate analysis for sulfur, ranged from 0.97 to 1.20 weight-
percent. Using these figures, the TCP's sulfur removal effi-
ciency averaged 90 percent.
According to Texaco, the MRL systems for acid gas re-
moval are designed to process a wide variation (flow and
composition) of gas streams based on the developmental-
nature of the research activities conducted there. It is expected
that systems designed to meet the specific requirements of
proposed commercial TCP units will provide higher removal
efficiencies.
Metals Partitioning
The fate of the spike metals in the slurry (lead and barium)
appeared to depend on their relative volatilities under TCP
operating conditions. Lead- a volatile metal-concentrated in
the clarifier solids, which were scrubbed from the raw syngas.
Lead probably evaporated in the hot regions of the gasifier and
condensed on the fine particles in the cooler areas of the
process. The more refractory barium did not concentrate in any
particular solid residue. It partitioned throughout the solid re-
sidual streams roughly in proportion to the mass of each
residual stream.
As presented in Table 6, average lead concentrations
were 880 mg/kg, 329 mg/kg, 491 mg/kg, and 55,000 mg/kg in
the Demonstration slurry, coarse slag, fine slag, and clarifier
solids, respectively. Although the clarifier solids comprised only
1.6 weight-percent of the solid residuals, they contained 71.1
weight-percent of the measured lead in all the solid residuals.
The remaining 28.9 weight-percent of the lead partitioned to
the coarse and fine slags.
Average barium concentrations were 2,700 mg/kg, 11,500
mg/kg, 15,300 mg/kg, and 21,000 mg/kg in the demonstration
slurry, coarse slag, fine slag and clarified solids, respectively.
The barium partitioned to the solid residual streams in approxi-
mate proportion to the mass flow of each stream. The coarse
slag, which comprised 62.5 weight-percent of the solid residu-
als, contained 55 weight-percent of the measured barium in the
-------
Table 6. Mass Flow Rates and Total Concentrations of Lead and Barium in Slurry Feed and Solid Residuals*
Slurry
(SL-1)
Coarse slag
(S-3)
Fine slag
(S-4)
Clarifier solids
(S-5)
Now rate (/b/h)
Range
Average
% of Residuals
Pb concentration (mg/kg)
Range
Average
Pb mass rate
Average (Ib/h)
% of Slurry Pb
% of Residuals Pb
Ba concentration (mg/kg)
Range
Average
Ba mass rate
Average (Ib/h)
% of Slurry Ba
% of Residuals Ba
2,212-2,291
2,216
867-899
880
2.00
1,750-3.580
2,700
6.1
250-307
273
62.5
198-542
329
0.09
4.5
15.3
8,090- 16,300
11,500
3.1
50.8
55.0
151-167
157
35.9
217-651
491
0.08
4.0
13.6
11,800-18,300
15,300
2.4
39.3
42.5
3.1-10.5
6.8
1.6
43,400-72,000
55,000
0.42
210
71.1
15,100-26,300
21,000
0.14
2.3
2.5
Mass flow rates and metal concentrations for slurry are on as-received basis; for solid residuals are on dry basis.
Note -A list of conversion factors is included at the end of the text.
Pb: lead
Ba: Barium
solid residuals. The remaining 45 weight-percent of the barium
partitioned to the fine slag and clarifier solids in approximate
proportion to their mass flow.
Process Wastewater
The Demonstration produced three process wastewater
streams: process wastewater (flash tank blowdown and quench/
scrubber and lockhopper water inventory on shutdown); gasifi-
cation vacuum filtrate (produced from the vacuum filtration of
the clarifier bottoms); and neutralized wastewater from the
sulfur removal unit. Samples from each of these streams were
collected and analyzed for VOCs, SVOCs, PCDD/PCDF, met-
als, pH, and organic and inorganic halogens. Samples of the
inlet water stream were also analyzed to determine if it was
introducing any contaminants of concern.
Lead concentrations in the process wastewater and vacuum
filtrate ranged from 12.4 to 38.9 mg/L and from 3.98 to 18.4
mg/L, respectively. Although the majority of the lead was found
in the clarifier solids, small amounts of lead or lead compounds
remained suspended in the clarifier overhead and traveled to
the process wastewater as the flash tank blowdown. Similarly,
small amounts of lead remained suspended in the vacuum
filtrate and did not settle in the clarifier solids.
Trace concentrations of VOC and SVOC PIRs such as
benzene, acetone, carbon disulfide, methylene chloride, naph-
thalene and naphthalene derivatives, and fluorene were found
in the wastewater streams. No concentrations of PCDDs or
PCDFs were found at or above the method detection limit of 10
nanograms per liter
Inorganic chloride concentrations in the wastewater streams
ranged from 380 mg/L to 6,800 mg/L. These values were, in
general, an order of magnitude higher than the concentrations
found in the inlet water; they indicated the presence of addi-
tional chlorides in the feed. Ammonia was also detected in the
process wastewater and vacuum filtrate streams; the pH val-
ues of these streams were fairly neutral. The inorganic chloride
concentrations indicated the presence of chloride, but the neu-
tral pH values indicate that the chloride species is not acidic.
These results show that the HCI produced in the gasification
process was removed in the quench and scrubber, neutralized
by the ammonia, and discharged in the process wastewater/
vacuum filtrate effluents.
Concentrations of organic chloride in the inlet water rang-
ing from 680 mg/kg (Run 3) to 2,500 mg/kg (Pretest) were
carried through the system to the wastewater streams. Similar
concentrations appeared in the process wastewater, vacuum
filtrate, and neutralized wastewater streams.
For proposed commercial units, the wastewater streams
would be treated on-site for recycling or for disposal as non-
hazardous water.
Overall Unit Cost
Information available to date on capital and operating
costs is preliminary. According to Texaco, an overall treatment
cost of $308/ton of soil is estimated for a transportable unit
designed to process 100 tpd of soil with characteristics similar
to that from the Purity Oil Sales Superfund Site, based on the
production of a marketable syngas product valued at $1.00/
10
-------
million Btu. Texaco estimates an overall treatment cost of
$225/ton of soil for a stationary unit designed to process 200
tpd of soil at a central site, with characteristics similar to that
from the Purity Oil Sales Superfund site, based on a value of
$2.00/million Btu for the syngas product.
These costs include amortized capital costs and all operat-
ing costs. They exclude waste soil handling, waste site-specific
roads and facilities, and permitting and regulatory costs, which
can be extremely variable and are the obligation of the site
owner or responsible party at the waste site. Actual costs will
vary depending on the site and the soil matrix being treated.
Overall Unit Reliability
The SITE demonstration experienced three operational
incidents which were identified and resolved prior to startup or
during operation; they did not require the shutdown and disrup-
tion of the demonstration operations. A major earthquake also
occurred one day prior to the scheduled demonstration test.
Based on the minimal disruptions caused by these incidents
and the continuous post-demonstration processing of the re-
maining slurry inventory, the reliability and efficiency of the
proposed commercial TGP units will be consistently high, and
they are expected to operate at on-stream efficiencies of 70%
to 80%. The downtime allows for scheduled maintenance and
intermittent unscheduled shutdowns such as those caused by
materials-handling equipment problems due to variations in,
and the abrasive nature of, soil and coal matrices.
Technology Status
A demonstration was conducted in 1988 at MRL for the
California Department of Health Services where petroleum
tank bottoms from a California oil production field were: co-
gasified with low-sulfur, western coal. This California-desig-
nated hazardous waste was fed to the gasifier at a rate of 600
Ib/h mixed with 2,400 Ib/h of coal. The dry syngas was com-
posed of 39% carbon monoxide, 38% hydrogen, and 21%
carbon dioxide. Texaco reported that the solids were non-
hazardous, based on California Assessment Manual limits for
total and leachable metals in effect at the time of the demon-
stration and the solids and wastewater were free of trace
organics and EPA priority pollutants.
Texaco has announced plans to build a $75-million TGP
power facility at its El Dorado, KS refinery, which will convert
about 170 tpd of non-commercial petroleum coke and refinery
wastes into syngas. The syngas, combined with natural gas,
will power a gas turbine to produce approximately 40 MW of
electrical power-enough to meet the full needs of the refinery.
The exhaust heat from the turbine will produce 180,000 Ib/h of
steam-approximately 40% of the refinery's requirements. Con-
struction will begin during the first quarter of 1995, with startup
projected for the second quarter of 1996.
Disclaimer
The initial conclusions presented herein are preliminary.
The data will be reviewed by the appropriate EPA Quality
Assurance/Quality Control Officer and addressed at length in
the Innovative Technology Evaluation Report.
Sources of Further Information
EPA Contact
Marta K. Richards
EPA SITE Project Manager
U.S. EPA
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
(513) 569-7692
Fax: (513) 569-7549
Technology Developer
Richard B. Zang
Texaco Project Manager
Texaco Inc.
2000 Westchester Avenue
White Plains, NY 10650
(914)253-4047
Fax: (914) 253-7744
Conversion Factors
English (US)
1 foot (ft)
1 square foot(ft2)
Length:
Area:
Volume:
1 gallon (gal)
1 cubic foot (ft3)
Mass: 1 grain (gr)
1 pound (Ib)
1 ton (t)
Pressure 1 pound per square inch (psi)
1 pound per square inch (psi
Energy. 1 British Thermal Unit (Btu)
1 kilowatt hour (kWh)
Temperature: ("Fahrenheit (°F) - 32)
x Factor = Metric
x 0.305 = meter (m)
x 0.0929 = square meter (m2)
x 3.78 = liter (L)
x 0.0283 = cubic meter (m3)
x 64.8 = milligram (mg)
x 0.454 = kilogram (kg)
x 907 = kilogram (kg)
x 0.0703 = kilogram per square centimeter (kg/cm2)
x 6.895 = kilopascal (kPa)
x 1.05 = kilojoule (kJ)
x 3.60 = megajoule (MJ)
x 0.556 = "Celsius (°C)
-------
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
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