United States
Environmental Protection
Agency
Hazardous Waste Engineering Research*
Laboratory
Cincinnati OH 45268 x/f, O
Research and Development
EPA-600/S2-84-174 Jan. 1985
Project Summary
Systems Reliability and
Performance: Pilot-Scale
Incineration of Chlorinated
Benzenes at the Combustion
Research Facility
Frank C. Whitmore, Robert W. Ross, Jr., Robert L. Durfee, Charles F. Fowler,
and Donald H. Sargent
A series of 34 test burns was con-
ducted between August 1983 and Jan-
uary 1984 in the pilot-scale rotary kiln
incineration system at the USEPA Com-
bustion Research Facility (CRF), using
chlorinated benzenes as surrogate princ-
ipal organic haiardous components
(POHCs). over a range of feed composi-
tions, POHC feed rates, rotary kiln
temperatures, and afterburner temper-
atures. The CRF rotary kiln system
consistently produced destruction and
removal efficiency (ORE) values above
99.99% for the chlorinated benzenes
POHCs. ORE values below 99.99%
were obtained during several types of
failure mode simulations (flame-out in
kiln or afterburner). A large number of
products of incomplete combustion
(PICs) were produced and identified, a
number of which are toxic or possibly
carcinogenic. Deliberate reduction of
excess air levels resulted in significant
production of soot and PICs but did not
produce higher levels of CO in the
combustion gases. Hot-zone sampling
just downstream of each of the two
combustion chambers provided for the
detailed study of PIC formation and will
facilitate the future development of
models of the incineration process.
Helium injection techniques were used
to determine combustion gas flow rates
and to measure residence time distribu-
tions (which directly affect destruction
efficiencies). This report was submitted
in fulfillment of Contract 68-03-3128
by Versar, Inc. under the sponsorship of
the U.S. Environmental Protection
Agency.
This Project Summary was developed
by EPA's Hazardous Waste Engineering
Research Laboratory, Cincinnati, OH,
to announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
The USEPA Combustion Research Facil-
ity (CRF) located in Jefferson, Arkansas,
has as its overall mission the detailed
physical and chemical study of the incin-
eration of hazardous wastes in highly
instrumented and closely controlled pilot
scale incineration systems. Experimenta-
tion to date has been in a rotary kiln/after-
burner system with venturi and packed-
tower wet scrubbers. A liquid injection
system and a stack gas carbon absorption
unit are currently being installed and
should be operational at the CRF by
November 1984.
Objectives
1. To develop methods of improving
the reliability and control of the
incineration process.
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2. To develop relationships for predict-
ing the performance of incinerators
of varying scale and design.
3. To develop a technically defensible
data base leading to additional
understanding of the hazardous
waste incineration process and to
further the development of methods
to predict the performance of incin-
erators as a function of key process
operating variables.
4. To develop incinerator system per-
formance data for regulated hazard-
ous wastes to support current RCRA
incinerator regulations and perform-
ance standards, and to provide
additional technical basis for those
future standards which may be
necessary.
During the two years of activity on the
CRF Program, the facility has been com-
pleted and equipped; master plans for
Project QA/QC, Health and Safety, and
facility operation and maintenance have
been developed and implemented, as has
a Master Research Plan for Fiscal Year
1984. Also, extensive modifications have
been made to the rotary kiln system, and
an important test burn series with sim-
ulated hazardous wastes has been com-
pleted. The RCRA Part B Hazardous
Waste Incineration Permit for the CRF was
recently issued by the State of Arkansas.
The CRF rotary kiln system, sampling
and analytical support functions, and the
supporting Health/Safety and QA/QC
activities are fully operational and capable
of routine operation with many types of
hazardous wastes.
Experimental Facilities
The CRF is housed in a 3000-square-
foot concrete block building containing an
incinerator room with an area of approx-
imately 1400 square feet. The facility also
contains a control room, analytical labor-
atories, and an instrument laboratory.
Support facilities are housed in several
trailers located adjacent to the CRF.
At the present time, the experimental
system that is available at the CRF is a
pilot-scale rotary kiln with afterburner
and an air pollution control system con-
sisting of a variable throat venturi, wetted
elbow and packed tower scrubber. At
present, liquid and semiliquid waste
materials are fed by a positive-displace-
ment pump through a water-cooled feed
lance mounted to the front face of the
kiln. A newly designed feed face, presently
being fabricated, will have provisions for
liquid and semiliquid feeds through a
variety of lance configurations and for
solids or containerized solids using a ram
feed device. The new feed face will also
accommodate a burner. Installation of
this new equipment willtakeplaceduring
1984.
Analytical capability for organics at
present includes two Hewlett Packard
Gas Chromatographs with Autosamplers,
a High Pressure Liquid Chromatograph
and associated sample preparation equip-
ment. Hot-zone sampling is available in
both the kiln and the afterburner transfer
ducts to complement sampling of stack
gases. Real-time monitoring of Oz, CO
and COa levels is provided by an auto-
mated system. The EPA Method 5, Mod-
ified Method 5 (using cooled XAD-2 resin
collection medium), and the volatile or-
ganics sampling train (VOST) are routine-
ly used for organic sampling. An on-line
total hydrocarbon analyzer will be in-
stalled in the immediate future.
Experimental Results,
Energy and Material Balance
Material balance and the heat balance
data from some early test burns are given
in tabular form in the final report. Some of
the pertinent results from analysis and
interpretation of engineering test data
from those early burns are summarized
below:
Data from 20 runs for 14 continuous
measurements provide a measure of
how closely steady-state test condi-
tions were maintained during the test
burns. Except for the kiln pressure (a
small negative value), the relative
standard deviation was no greater than
7.5 percent, showing that the system
test conditions were reasonably close
to steady-state.
Three independent determinations of
combustion gas flow rate showed
consistent differences of up to 19
percent. The helium tracer technique
has been refined to correct this incon-
sistency, with the development of a
helium measurement system consist-
ing of a sample loop and programmed
solenoid valves, and with more fre-
quent measurements in recognition of
the true flowrate fluctuations with time
introduced by the burner control
systems.
Reynolds numbers in the kiln range
from 2300 to 6700, which is in the
transition zone between laminar and
turbulent flow regimes. Other ranges
are:
Kiln transfer
duct -NRE= 5100-14800
Afterburner -NRE= 7800-13100
Afterburner
transfer duct -NRE= 16800-27000
Heat losses and heat fluxes were
calculated for major portions of the
system. For example, it appears that
about half of the heat input to the kiln
is lost to the surroundings. For the
entire system, from kiln to a point
between the afterburner and scrubber,
average heat losses were about 37
percent of thetotal system heat inputs.
Results from Chlorinated
Benzenes Test Burn Series
A system test series using hexachloro-
benzene(HCB)and1,2,4-trichlorobenzene
(TCB) as surrogate hazardous waste
materials was initiated in August 1983 to
demonstrate the following objectives:
Stable operation of each subsystem
and of the complete integrated system,
for extended testing times.
Independent control of operating con-
ditions for each test in accordance
with the predetermined test plan.
Acquisition and analysis of system
reliability and engineering test data.
Acquisition and analysis of exhaust
stack analytical data on HCB and TCB
as surrogate POHCs at a precision
more than sufficient to determine
Destruction and Removal Efficiency
(ORE) to 99.999%.
Development of preliminary informa-
tion on pic measurement methods and
identification of potential PICs from
HCB and TCB.
A total of 34 test burns of 8 to 10 hours
duration were performed beginning with
final engineering checkout runs in August
1983 and ending on 26 January, 1 984. In
addition to test burns over a range of feed
compositions, POHC feed rates, rotary
kiln temperatures, and afterburner tem-
peratures, tests were run in which various
hot-zone sampling methods were evalu-
ated, combustion failure modes were
simulated, and test methods for residence
time distribution were performed.
This test series produced data neces-
sary to determine the ORE for POHCs
across the entire rotary kiln incineration
system, the Destruction Efficiency (DE)
for each of the two combustion chambers,
and the partial identification and quanti-
fication of PICs. The measurements for
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these determinations included the char-
acterization of the waste feed material,
quantification of the waste material feed
rate, the chemical analysis of time-inte-
grated samples (at known sampling rates)
taken from the stack and from hot zones
downstream from each combustion cham-
ber, and the measurement of total flow
rate in the stack and at each hot-zone
sampling point.
The final report contains a complete
summary of the input-output data and
ORE values for the two POHCs, HCB and
1,2,4-TCB, in this test series. The rotary
kiln system consistently produced ORE
values above 99.99 percent for refractory
POHCs such as chlorinated benzenes.
The ORE values for 1,2,4-TCB were higher
than for HCB under comparable residence
time/temperature conditions.
Conclusions
From the data, there appears to have
been essentially no variation of measured
ORE for either HCB or TCB with combined
temperature/residence time. Over the
feed rate range of 100 to 1000 gm/hr,
there also was no discernable effect of
feed rate on ORE. Except for excursions
during startup and shutdown, carbon
monoxide levels were below 1 ppm during
all of these tests; thus, the CO level did
not appear to depend on feed rate or
temperature/residence time over the
range covered.
After a test burn with either HCB or
1,2,4-TCB in the feed, POHC emissions
were found during subsequent tests
wherein the only feed to the kiln was
propane fuel. The source of this holdup
(or residue) effect during intermittent
system operation is as yet undetermined,
as is its significance to steady-state
commercial incineration operations.
Hot-zone sampling upstream and down-
stream of the afterburner permitted
measurement of the destruction effici-
ency in the afterburner, DEAu. The
analyses for POHCs in the upstream
samples show that most of the thermal
destruction occurred in the kiln. The
results were indicative that complex
chemical interactions occur in the after-
burner. In the case of HCB as the POHC,
for example, previously formed PICs may
react to form additional HCB in the
afterburner. Under some conditions,
POHC output from the afterburner was
greater than the POHC input to the
afterburner. This could result from PIC
reactions, holdup from previous burns, or
3 combination of these effects.
A number of PICs, notably polyaromatic
hydrocarbons (PAHs) and other chlori-
nated benzenes, were formed in the tests
with HCB/toluene or TCB/toluene feed.
Agreement between GC/MS and multi-
detector GC identification of PICs was
very good.
Analytical data from hot zone samples
show that the concentrations of organic
compounds found did not correlate with
particulate levels, which supports the
assertion that the organic molecules are
in the vapor state (not strongly associated
with particulates) in the hot zones.
Several tests in this series were
conducted to simulate failure modes in
the rotary kiln system. Flame-out of either
the kiln burner or the afterburner was
simulated by intentional temporary but
repeated shutdown of each burner.
Temporary loss of either burner did not of
itself result in the system being out of
compliance. Deliberate reduction of ex-
cess air levels resulted in significant
production of soot and PICs but did not
produce higher levels of CO in the com-
bustion gases.
F. C. Whitmore, R. W. Ross, Jr., R. L Durfee, C. F. Fowler, andD. H. Sargent are
with Versar, Inc., Pine Bluff, AR 72079.
Richard A. Carnes is the EPA Project Officer (see below).
The complete report, entitled "Systems Reliability and Performance: Pilot-Scale
Incineration of Chlorinated Benzenes at the Combusiton Research Facility,"
(Order No. PB 85-121 184; Cost: $20.50, subject to change) will be available
only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Hazardous Waste Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati. OH 45268
* U S GOVERNMENT PRINTING OFFICE, 1985 569-016/7897
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United States
Environ.[jj£rjjal Protection
Agency,,.. __.
Center for Environmental Research
Information
Cincinnati OH 45268
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