EPA/600/A-95/037
mmmm
CONFERENCE PROCEEDINGS
Volume One
November 29-December 1,1994
Sheraton Washington Hotel
Washington, DC
Conference Co-organized by
Hazardous Materials Control Resources Institute
and
E.J. Krause and Associates, Inc.
Conference Proceedings Published by
Hazardous Materials Control Resources Institute
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U.S. EPA'S EVALUATION OF A TEXACX) GASIFICATION TECHNOLOGY
Marts K. Richaids
USEPA - Risk Reduction Engineering Labomtoiy
Cincinnati, Ohio
Seymour Rosenthal
Foster Wheeler USA Cot?
Edison, New Jeisey
ABSTRACT
The U. S. Environmental Protection Agency's (EPA's)
Superfiind Innovative Technology Evaluation (SITE)
Program selected the Texaco Inc. gasification technology
for evaluation by field testing • a Demonstration, which
occurred in the Winter of 1994. A series of test runs was
conducted at the Texaco Montebello Research Laboratory
(MRL) facility in South El Monte, California, using 40 tons
of waste slurry, which included waste soil from die Purity
Oil Sales (POS) Superfiind site in Fresno, California. Hie
waste soil contained volatile and setnivolatile hydrocarbons
as well as lead, barium, and other metal compounds.
The Texaco Gasification Process is a patented high-
temperature, high-pressure, partial-oxidation process
designed to destroy the organic contaminants and
immobilize the metals at die same time that it produces a
useable synthesis gas product that Texaco calls syngas.
INTRODUCTION
As a response to a Congressional mandate, die U.S.
Environmental Protection Agency (EPA) has focused on
policy, technical, and informational issues related to
exploring and applying ne^v remediation technologies fijr
Superfiind sites. One such initiative addressing these issues
is EPA's Superfiind Innovative Technology Evaluation
(SITE) program, which was established to accelerate
development, demonstration, and use of innovative
technologies for site cleanups.
The U.S. EPA SITE Demonstration of the Texaco
Gasification Process (TGP) was conducted at the Texaco
Montebello Research Laboratory (MRL) in South El Monte,
California, using contaminated soil from die Purity Oil
Sales Superfiind site in Fresno, California. The TGP
technology is designed as a high-temperature, high-pressure
gasification process that, according to Texaco, produces a
useable/marketabk product gas and non-leachabk, glassy
slag from a liquid slurry waste feed material.
Primary project objectives included the following:
• Evaluate the technology's ability to treat waste materials
to form a useable synthesis gas
• Evaluate die technology's ability to produce nonhazardous
solid residuals
• Assess the ability of the technology to achieve 99.99%
destruction and removal efficiencies (DREs) for specific
organic contaminants.
Secondary objectives of the TOP demonstration woe:
• Develop overall capital and operating costs for the
technology
• Assess die reliability and efficiency of TGP operations
OVERVIEW OF 1HE SITE DEMONSTRATION
For the Demonstration, contaminated soil from die Purity
Oil Sales Superfiind Site in Fresno, California was
transported to die MRL for treatment. To meet TGP and
SITE needs, various other compounds/substances woe
added to the waste feed for slurry preparation including
coal, water, clean soil, slurry additives, and several spiking
compounds - heavy metal compounds (lead and barium)
and a volatile organic compound (chlorobenzcne).
Three replicate tests were conducted. Shiny was fed to
the gasifier lit approximately 2200 IbThr. The total amount
of slurry treated during the three test runs was
approximately 40 tons; and die total amount of slurry
Superfiind XV Conference and Exhibition
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treated during the entire Demonstration, which included
initial shakedown, system start-up, a pre-test run, the three
replicate test runs, and post-Demonstration processing of
die slurry inventory, was approximately 100 tons.
Extensive process operating data and numerous analytical
data were collected. Critical process parameters included
slurry feed rate; raw syngas, flash gas, and fuel gas flows;
makeup and effluent water flows (except neutralized
wastewater); weight of coarse slag, fine slag, and clarifier
solids; and organic spike flow rate. Critical
chemical/analytical parameters included VOCs,
PCDD/PCDF, and metals in all feed and discharge streams
(except neutralized wastewater); TCLP analyses on waste
feed, slurry feed, coarse slag, fine slag, and clarifier solids;
and compositions of process gas streams.
Information on the TGP and preliminary results of the
SITE field Demonstration at the Texaco MRL are provided
herein.
TECHNOLOGY DESCRIPTION
The TGP is an innovative extension of Texaco's
conventional fuels gasification technology that converts
carbonaceous organic materials into a mixture 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 2200°F.
(1200°CXabove the melting point of the ash in the feed
stream) and at pressures above 250 psig. At these
temperatures and pressures, the TGP should destroy any
organic in the feed. The raw synthesis gas (syngas) that is
produced should consist mainly of hydrogen and carbon
monoxide. The syngas, as an intermediate product, could
be used to produce power or chemicals. The residual metals
and inorganic components of the feed should iota a glassy
slag thai is non-hazardous, based on the Toxicity
Characteristic Leaching Procedure (TCLP) and die
California Waste Extraction Test (WEI) Soluble Threshold
Limit Concentration (STLC) standards.
This SITE Demonstration employed the MRL's High
Pressure Solids Gasification Unit D (HPSGU II). Figure 1
shows a block flow diagram identifying the TGP and the
major MRL subsystems used in this demonstration. Figure
2 presents a schematic flow diagram of die HPSGU II used
in this Demonstration. The following technology
description presents a portrait of die MRL TGP used during
the SITE Demonstration.
The Purity Oil Sales Superfund site soil, excavated for
treatment is the TGP, was site-treated with lime to a pH
greater than 4 and screened to a particle size less than '/«
inch.
SWMr Grinding md Stony Pnpmmhm
The slurry feed used in die Demonstration was a blend of
the Purity Oil slurry and a clean soil slurry. To prepare the
slurries, coal and clean soil were precrushed in a tiawm^r
mill. For each shiny, the precrushed product (which
includes the site-processed Purity Oil waste soil) was then
combined with water, an ash fluxing agent and a slurry
viscosity reducing agent in a rod mill where the mixture
was ground and slurried. Hie mill product was screened to
remove oversize material and transferred to the HPSGU II
slurry storage tanks where the inorganic spikes (lead and
barium) were added.
High Pressure Solids Gmlfle*Um Unit H
The slurry was gasified in MRL's HPSGU II (Figure 2).
This unit includes equipment for slurry feeding,
gasification, gas scrubbing and cooling, slag removal, fines
removal and process water handling.
During the Demonstration, the slimy was mixed with the
organic spike (cUorobenzene) as it was pumped into die
gasifier where it was combined with oxygen to produce hot
syngas and molten stag. The oxygen-to-slurry ratio was
controlled to obtain an average operating temperature of
1400°C (2550°F.). The average pressure was 500 psig.
Hie hot syngas and molten slag were cooled in a water
quench. The syngas was then scrubbed of particulates with
additional water, coded to near ambient temperature and
routed to MRL's Acid Gas Removal Unit More than 99%
of the chlorides in die syngas are transferred to the
circulating water in these step.
Hie slag, a glassy solid after qnenrhmg, was removed as
a slag/water mixture using a lockhopper. This mixture was
passed over a screen to separate out the com* slag. Hie
flae slag was recovered using a vacuum belt fiher. The
vacuum belt filter underflow water was then returned to the
lockhopper system fix-reuse.
Water from die quenching md scrubbing steps was
combined and cooled. Any solids in die combined stream
were then removed using a clarifier (clarifier bottoms),
which were withdrawn from the unit md filtered using a
vacuum filter, producing a clarifier solids cake and vacuum
filtme.
The clarifier overhead water was combined with the
condensate from die cooling of die raw syngas and flashed
Superfund XV Conference and Exhibition
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to remove dissolved gases (flask gai). Except far a mall
wastewater blowdown stream, die flashed water was
recycled to tbe quench and scrubber.
The wastewater blowdown and vacuum filtrate were touted
to temporary storage for testing prior to treatment and
disposal.
Acid Gm Removd/Sidfw Removal
During the Demonstration, MRL used a regenerate
solvent process (Selexol) to separate out and CO, (add
gases) from die raw syngas. Die raw syngas was contacted
by the solvent, which removed tbe acid gases to produce a
low sulfur content fkiel gas. The fuel gas was then flared.
The acid gases were stripped from the solvent and
combined with the gasification system flash ps and fed to
the Sulfur Removal Unit where the H2S was absorbed using
a caustic solution, lie dissolved sulfides were oxidized
using air and steam, producing a solution of sodium
thiosulfate. This was then neutralized and routed to
wastewater treatment
As with the fuel g&s stream, die Sulfur Removal Unit
absorber and oxidfeer off-gas streams were flared.
TECHNOLOGY APPLICABILITY
The TGP can process a variety of waste streams.
Virtually any carbonaceous hazardous or non-hazardous
waste stream can be processed in die TGP.
Depending upon the physical and chemical composition
of die waste stream, it can either be toed as tbe primary
feed to the gasifier or it can be co-gasified along with a
high-Btu fuel such as coal, petroleum coke, or oil. The
choice is based on the following factors:
The feed must be shnried successfully.
• The heating value of the feed must maintain die
gasifier temperatures.
The fusion temperature of die ash in die feed roust
fall within operational limits.
TECHNOLOGY UMTTAHONS
Texaco expects to design TOP fhcilities with flexible and
comprehensive storage and pretreatment systems capable of
processing a wide range of waste matrices slurried with
coal, water, and additives. If the specific site waste
exhibits some unusual physical or chemical characteristics
that would affect the ability of the pretreatment module to
slurry the feed, additional pretreatment equipment may be
added on-site to supplement the existing design.
The unit's complexity, coat, and economic reliance .on a
tie-in to its syngas product mandates that remediations
should he limited to relatively large-scale sites and long-
torn remediations with a minimum of25,000 tons of waste
feed and about 2 years of operation.
PROCESS RESIDUALS
Solid products, including coarse slag, fine slag, and
clarifkr solids are stored, characterized, and properly
disposed of; based on their hazardous or non-hazardous
characteristics. In most cases any excess water produced
will be amenable to conventional wastewater treatment
technologies.
PERFORMANCE DATA
To assess the TOP operation and its ability to process a
RCRA hazardous waste feed that does not comply with
TCLP and WET regulatory requirements, die contaminated
test soil was spiked with lead nitrate and barium nitrate
(hiring shiny preparation. Additional shiny was prepared
using a clean soil spiked with barium nitrate. To ensure a
sufficient concentration of a principal organic hazardous
constituent (POHC) for DRE determination, chkxobenzene
was added to die mixed test shiny at die point of slurry
feed to die gasifier.
The prefimiiiaiy results from this SITE Demonstration are
presented below. Table 1 shows tbe TCLP analytical results
for lead and barium in die slurry feed (and its major
and that of die various solid residuals. The
DRE results are shown in Table 2. Syngas composition is
given in Table 3.
Tot SoBds Lemkhtg Chtncteristio
The leach test results mdkntwl misted bitthm in meeting
the teachability goals for die test Directives. The average
TCLP ad WET measurements ftr the test shmy feed were
higher than the regulatory requirements for lead httt lower
than the requirements for barium. The average TCLP and
WET measurements for coarse stag, which comprised
approximately 61 wt% of the total solid residuals, were
lower than die TCLP regulatory requirements for lead and
barium and tbe WET regulatory requirements for barium.
The average TCLP and WET measurements for die fine
slag, which constituted about 36 wt% of die total solid
residuals, and die clarifkr solids which amounted to 3
wt.%, were higher dun the TCLP and WIT regulatory
requirements for lead but lower than die tests' requirements
for barium.
The SITE Demonstration showed that die mobility of the
lead in die main residual solid product — the coarse slag
Superfund XV Conference and Exhibition
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— was decreased, compared to the lead in the
contaminated/spiked Mil. The mobility of the barium
remained essentially unchanged.
Hie average WET metsurements for all solid residual
streams were higher than die WET regulatoiy requirements
for lead. However, the TCP demonstrated significant
improvement in reducing lead mobility as measured by die
WET results.
Destruction mid Removal Efficiency (DUE)
For these TCP SITE tests, DRE was die measure of
organic destruction. This parameter was determined by
analyzing the concentration of die chlorobenzene POHC in
the test slurry and the effluent gas stream(s) and was
calculated in two ways. For both cam, the inlet flow of
die chlorobenzene POHC was measured from die metering
pump flow. For the gasification process only, the effluent
gas stream was the raw syngas - before acid-gas and sulfur
removal; for die overall TCP operation, the effluent gas
streams encompassed all the gas after die acid-gas and
sulfur removal systems. As shown in Table 2, die TCP
achieved DREs greater than 99.99 percent for the
chlorobenzene POHC.
Syndmk Gm Product Composition
Hie synthesis gas (syngas) product from die TCP is
composed primarily of hydrogen, carbon monoxide, and
carbon dioxide. For a commercial unit, the raw syngas
would be further treated in an acid gas system for the
removal of hydrogen chloride and carbooyl sulfide. This
would produce a medium-Btu fuel gas that can be burned
directly in a gas-turfeine/electrical-generatioo facility or
synthesized into other chemicals. The raw gas fins die
gasifter was sampled and analyzed to evaluate die TCP's
ability to gasify a slurry containing RCRA hazardous waste
material and produce • synthesis gas product. This g»s
stream was then treated in die Texaco MRL acid gas
removal system; the resulting fuel gas product was flared.
Table 3 shows die compositions of the raw syngas and die
fuel gas product.
OVERALL UNIT COST
Information available on capital and utility costs are
being evaluated.
OVERALL UNIT RELIABILITY
The SITE Demonstration experienced three operations
incidents which were identified and resolved either prior to
startup or during operation and did not require the
shutdown and disruption of TCP operations. A major
earthquake also occurred prior to the Demonstration,
requiring minor repairs that did not significantly interfere
with the Demonstration start-up schedule. Based on the
minimal disruptions caused by these incidents and the
continuous post-demonstration processing of the remaining
slurry inventory, it is expected that the reliability and
efficiency of the proposed transportable TCP will be
consistently high. Based on continuous operation, the
proposed unit is expected to be operating 292 days per year
(80% utilization factor).
TECHNOLOGY STATUS
Texaco has announced plans to build a 75-million dollar
TCP power facility at its El Dorado, Kansas reffaiery, which
will convert about 170 tons per day of noncommercial
petroleum coke and refinery wastes into syngas. The
syngas, combined with natural gas, will power a gas turbine
to produce approximately 40 megawatts of electrical power
— enough to meet die full needs of the refinery. The
exhaust heat from die turbine will be used to produce
180,000 IbVhr. of steam — approximately 40% of the
refinery's requirements. Construction will begin during the
first quarter of 199S, with start-up projected for the second
quarter of 1996.
DISCLAIMER
The initial technology conclusions presented in this report
are preliminary, the data has not yet been reviewed by the
appropriate EPA Quality Assureoce^Qualily Control Officer.
Superftind XV Conference
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TABLE 1, TCLP ANP WET RESULTS • LEAD (Fb> mi BARIUM (Ba)
TCLP Pb (mg/1)
WET Pb (mg/1)
Range
Average
Range
Average
Regulatory limit
5.0
5.0
Purity Oil soil1
223
Clean soil (S-l)»
<0.03
_
Slurry (SL-1)J
i. 14-9.12
8.4
54-61
56
Coarse slag (S-3)
3.26-5.75
4.5
6.7-11.1
9.8
Fine slag (S-4)
11-18.7
IS
22.8-52.9
39.5
Clarifier solids (S-5)
691-1,170
913
903-1,490
1,167
TCLP Ba (mg/1)
WET Ba (mg/1)
Range
Avenge
Range
Average
Regulatory limit
100
100
Purity Oil soil'
329
Clean soil (S-l)1
1.85
Sluny (SL-1)1
0.111-1J
0.49
<5.0-6.5
<5.0
Coarse slag (S-3)
0.483-0.756
0.59
<5.0
<5.0
Fine slag (S-4)
1.16-1.99
1.54
5.6-10.4
8.5
Clarifier solids (S-5)
2.02-3.82
3J9
14-51.4
38.4
1 Purity Oil soil (waste feed to produce Purity oil shiny) with 15,000 ppm (as elemental lead) lead nitrate
spike and 30,000 ppm (as elemental barium) barium nitrate spike-measured in pretest spike study.
3 Clean soil is soil matrix used to produce clem soil slurry.
1 The SITE Demonstration slurry (SL-1) is a mixture of stories produced using Purity Oil soil and clean soiL
SL-1 is composed of 26,800 pounds of Purity Oil slurry mixed with 138,040 pounds of clean soil shiny.
Superfund XV Conference and Exhibition
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TABLE 2. DESTRUCTION AND REMOVAL EFFICIENCIES (DREs) TOR
PRINCIPAL ORGANIC HAZARDOUS CONSTITUENT (POHQ - CHLOROBENZENE
I Run
Win (Ibihr.)
DRE for Gasii
Wout (lb_/hr.)
ication Process
DRE %
DRE for Overall
Wout (IbJhr.)
TGP Operation |
DRE % |
1
622
0.000173
99.9972
<0.000122
>99.9980 |
2
6.38
0.000200
99.9969
0.000452
99.9929 |
3
6.67
0.000244
99.9963
0.000252
99.9962 |
| Average
6.42
0.000210
99.9967
<0.000279
>99.9956 |
Win « Mass feed rate of chlorobenzene (POHC) in the waste stream feed.
Wout - Mass emission rate of chlorobenzene (POHC) in gas emission streams
DRE - Win - WQUt x 100
Win
TABLES. SYNTHESS GAS COMPOSITION
Raw Syngas Composition and Heating Value [
Run
H,
(vol. H)
CO
(wl.%)
CO,
(vol %)
CH,
(ppwv)
N,
(voL%)
Ar
(vol. %)
COS
(jppBSV)
H,S
(ppnv)
TOC
(PPrav)
Hating I
value I
(Btu/ I
scf) |
34.6
33.0
25.9
«7
6.5
030
120
1,175
41.5
219 §
2
26.9
313
26.9
SI
5.1
0.00
171
3.050
17.0
210 |
3
35.4
39.6
262
42
5.7
0.05
125
1,910
14.0
221 |
Avenge
323
34.6
263
60
5.1
0.12
139
2,070
26.5
219 |
Fml Oas Coopockioa art Hetting Vatae
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FlQiif«1. Block flow diagram of MRLTGP during SITE Demonstration.
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OXYGEN
ORGANIC
SPIKE
WATER
COAL/SOIL HI
INORGANIC
SPIKE
on
I
W
SOLIDS GRINDING A
SLURRY PREPARATION
SLURRY
TANKC81
SLURRY
PUMP<8)
§**%%%%%%~%%%*
UUtXU*'**
GAS COOLING*
AaO OAS REMOVAL
CONDENSATE FROM GAS COOLING
<
FLASH GAS
SULFUR
SCRUBBER
REMOVAL
FLASH
TANK
KJ
MAKEUP WATER
/
WATER >
¦ WASTEWATER ..
R| TDATC
• Itf C w
f
STORAGE
VACUUM
FILTER
* COARSE SLAG
* FINE SLAG
+¦ CLARIFIER
SOLIDS
Figure 2. Schematic flow diagram of MRL's HPSGUII during SITE demonstration.
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