Demonstration Bulletin: Circulating Bed Combustor

&EPA
United States
Environmental Protection
Agency
EPA/540/MR-92/001
February 1992
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Demonstration Bulletin

Circulating Bed Combustor
Ogden Environmental Services, Inc.
TECHNOLOGY DESCRIPTION: The Ogden Circulating Bed
Combustor (CBC) is a thermal destruction system that uses
high-velocity air to entrain circulating solids in a highly
turbulent combustion zone. The combustion gases are
separated from the ash and hot solids. The solids return to
the CBC, the gases are filtered to the atmosphere and the ash
is trapped for disposal (Figure 1).

Solids, slurries, or liquids can be introduced into the chamber
loop where they contact hot bed material recirculating
through the cyclone. When introduced into the primary
combustion zone, the waste heats rapidly and continues to be
exposed to high temperatures (up to 1,800°F) throughout its
residence time High velocity air entrains the circulating soil,
which travels upward through the combustor and into the
cyclone. The cyclone separates the combustion gases from
the hot solids. The solids then are returned to the
combustion chamber via a proprietary non-mechanical seal.
Temperatures around the entire combustion loop are uniform
to within ±50°F. The hot flue gases and fly ash pass
through a combustive flue gas cooler into a baghouse filter
which traps the ash. Filtered flue gas then exits to the
atmosphere. Heavier particles of purified soil remaining in the
combustor lower bed are removed slowly by a water-cooled
bed ash conveyor system.

Acid gases and sulfur oxides formed during combustion are
captured by limestone added directly into the combustor.
Emissions of CO and NOX are controlled to low levels by the
turbulent mixing, low temperatures (1,425°F to 1,800°F),
and staged combustion achieved by injecting secondary air at
sequenced locations in the combustor.

WASTE APPLICABILITY: The Ogden CBC has been used to
treat low pH tar-like (asphaltic) residues containing elevated
concentrations of organic sulfur, aromatics, and aliphatic
hydrocarbons.

STATUS: Treatability studies and a demonstration test were
performed for the McColl superfund site in Fullerton,
California, under the guidance of the EPA SITE Program, EPA
Region IX, and DHS. These tests were conducted at the OES
research facility in San Diego, California in March 1989 to
provide data showing the effectiveness of treating the McColl
Waste before bringing a full-scale unit onto the McColl site.
A technical evaluation report will be forthcoming (Oct. 1991).
COMBUSTOR
STOCK
LIMESTONE
FEED
WASTE
FEED
Printed on Recycled Paper

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DEMONSTRATION RESULTS: Selected drums of McColl
waste were sampled to characterize the drum contents and
to select representative waste of the McColl site. The site
waste material was screened, divided into two sets of
feedstock {one blended with sand and the other left as raw
waste), and transported to the 'OES facility for processing.
Ogden Environmental Services operated and maintained the
CBC, and provided process monitoring and continuous
emissions monitoring (CEM). EPA conducted process inlet
and outlet stream sampling and analysis to determine the
system's operating efficiency and contaminant destruction
capabilities. Stack sampling and analysis were designed to
provide the data necessary to evaluate the CBC and assess
the environmental effects of this technology in a full-scale
SITE Demonstration test. Ash analyses were designed to
permit an evaluation of the disposal options for the ash
product. The McColl waste was processed through the CBC
without any difficulty. The organic material was effectively
destroyed as evidenced by the destruction removal' efficiency
(ORE) of 99.992%. Typically, ORE values are not calculated
for organic compounds in the waste feed unless they exist at
levels greater than 1,000 parts per million (ppm). No
significant levels pf hazardous organic compounds left the
system in the stack gas or remained in the bed and fly ash
material, as shown in the table below.

FOR FURTHER INFORMATION:

EPA PROJECT MANAGER:
Douglas W. Grosse
U.S. EPA
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, Ohio 45268
513-569-7844
FTS: 684-7844
FEED AND RESIDUALS CHARACTERISTICS

QRGANICS
(parts per million)
Benzene
Toluene
Xylene
Ethylbonzone
1/1.1. Trichloroethane
Naphthalene
2-Methyl-NaphthaIene
PHYSICAL PROPERTIES
Sulfur {%}
pH
Density (Ibs. per cubic ft.)
Heat Value (BTU/pound)
Waste Feed

4.9
35.5
165.0
23.0
not detected*
30.2
34.5

4.4
2.3
57.9
1387.0
Fly Ash

not detected
not detected
not detected
not detected
not detected
not detected
not detected

3.6
12.6
76.9
—
Bed Ash

not detected
not detected
not detected
not detected
not detected
not detected
not detected

0.9
12.1
88.4
—
Stack Gas
Emissions

0.0008
0.0015
0.0015
0.0004
0.0002
0.0006
0.0004

"
—
—
—
"not detected" indicates a value below detection limits.

Organic feed and heat values are based on unblended waste averages. All other results are based
on blended and unblended waste averages. Waste feed, fly ash and bed ash values are weight/weight.
Stack gas emissions are volume/volume.
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/540/MR-92/001

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