S-EPA
United States
Environmental Protection
Agency
EPA/540/MR-94/514
July 1994
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Demonstration Builetin
Texaco Gasification Process
Texaco line.
Technology Description: The Texaco Gasification Process
(TGP) has operated commercially for nearly 45 years on feeds
such as natural gas, liquid petroleum fractions, coal, and petroleum
coke. More than 45 plants are either operational or under devel-
opment in the United States and abroad.
Texaco has developed waste gasification as an innovative exten-
sion of their conventional fuels gasification technology that converts
carbonaceous materials containing organics into a mixture consist-
ing primarily of hydrogen and carbon monoxide by reacting them
with a limited amount of oxygen (partial oxidation) in a refractory-
lined gasifier at temperatures in excess of 2,200 F (above the
melting point of the ash in the feed stream) and at pressures greater
than 250 psig. According to Texaco, these temperatures and
pressures are sufficient to destroy any hydrocarbons and organics
in the feed and prevent the formation of undesirable hydrocarbon
by-products associated with other coal/fossil fuel conversion pro-
cessed.
The TGP produces a raw synthesis gas (syngas) as an intermediate
product which can then be used to produce hydrogen, ammonia,
methanol and other chemicals, as well as electrical power when
combusted directly in a gas turbine. Since the TGP is operating at
temperatures aibove the melting point of the ash in the feed stream,
the residual ash forms a glassy slag.
Waste feed, along with coal, oil, and/or coke, is ground and mixed
with water in a high solids concentration slurry (generally 55 to 70%).
OXYGEN
COAL
INORGANIC
SPIKE
SOIL
I I
, MAKE-UP
WATER
SOLIDS GRINDING
AND SLURRY
PREPARATION
COAL/WASTE
RAWGAS
(SYNGAS)
SLURRY
HIGH PRESSURE
SOLIDS
GASIFICATION UNIT
CAUSTIC/
ACID
FUEL GAS
ACID GAS
REMOVAL
TO
DISPOSAL
__
<4&
^
^
ORGANIC
SPIKE
COARSE SLAG
FINE SLAG
CLARIFIER SOLIDS
i
i*
=!L
U.C
1*
3°
r?
cd
WASTEWATER
TREATMENT
TO DISPOSAL
FILTER CAKE
NEUTRALIZED
ABSORBER OFF-GAS
OX|D|ZER OFF-GA
EFFLUENT WATER
TO SEWER
Figure 1. The Texaco Gasification Process
Printed on Recycled Paper
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The process feeds the slurry, along with oxygen or air, to the gasif ier
through an injector nozzle. Water serves as a reactant, a temp-
erature moderator, and atransport medium. Liquid and gas fuels,
which can be fed directly to the gasifier, need no pretreatment but
may require water or steam moderators. Chlorinated species in the
feed become hydrogen chloride in the raw syngas; the hydrogen
chloride solubilizes in the scrubber water before being purged from
the process. The sulfur in the feed becomes hydrogen sulfide or
carbonyl sulfide in the product gas. Commercial acid gas removal
and sulfur recovery processes scrub these sulfidesfrom the product
gas and recoverthe sulfur. The residual ash is recovered as aglassy
Waste Applicability: Since the TGP feed material is ground
and slurrled prior to introduction into the gasifier, virtually any type
of carbonaceous material can be processed in the TGP, provided
the pretreatment facilities are adequate to handle and treat the
Incoming material. Texaco reports that the TGP has been success-
fully demonstrated on coal liquefaction residues, petroleum pro-
duction tank bottoms, municipal sludge, and surrogate-contami-
nated soil. This SITE Demonstration was conducted to evaluate
the potential applicability of the TGP to treatment of a hazardous-
waste-contaminated soil matrix.
Demonstration Results: The January, 1994 SITE Demonstra-
tion took place at the Texaco Montebello Research Laboratory in
South El Monte, California. Figure 1 shows a block flow diagram
of the TGP demonstration unit. The slurry feed consisted of coal,
water, waste soil from the Purity Oil Sales Superfund Site in Fresno,
California, and clean soil. It was spiked with heavy metals (lead and
barium) to ensure that the feed contained sufficient levels of
contamination to fail the Toxicrty Characteristic Leaching Proce-
dure (TCLP) test. Addition of a volatile organic (chlorobenzene)
provided detectable levels in the product gases to facilitate the
calculation of the Destruction and Removal Efficiency (ORE).
Three replicate tests were conducted. Slurry was fed to the gasifier
at 2,200 to/hr. The total amount of slurry treated during the three
runs was approximately 40 tons. The total amount of slurry treated
during the entire Demonstration, which included scoping runs,
initial shakedown, system start-up, a pretest run, the three replicate
runs, and post-demonstration processing of the slurry inventory,
was approximately 100 tons.
Preliminary findings from the TGP SITE Demonstration are sum-
marized below:
• The average composition of the dry synthesis gas product
from the TGP consisted of 37% hydrogen, 36% carbon
monoxide and 21% carbon dioxide. No organic contami-
nants, other than methane (55 ppm), were above 0.1 ppm.
• The ORE forthe volatile organic spike (chlorobenzene) was
greater than the 99.99% goal.
• The primary TGP solid product, coarse slag, complied with
the TCLP regulatory requirement for lead (5 mg/L) and the
TCLP and California Waste Extraction Test (WET) regula-
tory requirements for barium (100 mg/L). The coarse slag
did not meet the WET standard for lead (5 mg/L).
• Volatile heavy metals, such as lead, tend to partition and
concentrate in the secondary TGP solid products—-fine slag
arid clarifier "solids'.! These secondary products did not
comply with the TCLP and WET regulatory requirements for
lead but did meet the standards for barium.
A Technology Capsule and an Innovative Technology Evaluation
Report will be available in the summer of 1994.
For Further Information:
Marta K. Richards
EPA SITE Project Manager
U.S. EPA
26 W. Martin Luther King Drive
Cincinnati, OH 45268
(513) 569-7692
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/540/MR-94/514
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