United States
 Environmental Protection
 Hazardous Waste Engineering Research*
 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
  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

 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.


 1.  To develop methods  of improving
    the reliability  and control of the
    incineration process.

 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

  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
  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

 • 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
 • Reynolds numbers  in the kiln range
   from 2300 to 6700, which is in the
   transition zone between  laminar and
   turbulent flow regimes. Other ranges
   Kiln transfer
     duct         -NRE=   5100-14800
   Afterburner    -NRE=   7800-13100
     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-
 (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

 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.
  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

United States
Environ.[jj£rjjal Protection
Agency,,..  __.
Center for Environmental Research
Cincinnati OH 45268
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