United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S8-89/057 May 1990
Project Summary
Municipal Waste Combustion
Assessment: Combustion
Control at New Facilities
P. J. Schindler
The EPA's Office of Air Quality
Planning and Standards (OAQPS) is
developing emission standards and
guidelines for new and existing
municipal waste combustors (MWCs)
under the authority of Sections
111 (b) and 111(d) of the Clean Air Act
(CAA). The EPA's Office of Research
and Development (ORD) is providing
support in developing the technical
basis for good combustion practice
(GCP), which is included as a
regulatory alternative in the
standards and guidelines. This report
provides the supporting data and
rationale used to establish baseline
emission levels for model plants that
represent portions of the planned
and projected population of MWCs.
The baseline emissions represent
performance levels that are expected
to be achieved by new plants in the
MWC population that incorporate
GCP. the baseline emissions, which
were developed using the data base
from the newest units in the existing
population of MWCs, establish
performance levels against which the
effectiveness and costs of emission
control alternatives can be evaluated.
This Project Summary was
developed by EPA's Air and Energy
Engineering Research Laboratory,
Research Triangle Park, NC, 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
On July 7, 1987, the U.S. EPA
announced its intent to develop air
emission standards for new municipal
waste combustors (MWCs) and
guidelines for existing MWCs under the
authority of Section 111 of the Clean Air
Act. The New Source Performance
Standards (NSPS) will apply to all MWCs
that commence construction after the
proposal date, and the guidelines will
apply to all MWCs not covered by the
NSPS. Following the July 1987
announcement, an extensive background
information development and data
gathering effort was initiated to provide
the technical support for the proposed
regulations. The NSPS and guidelines
development includes a performance
assessment of emission control
alternatives that are applied to
hypothetical model plants. The models
represent typical classes of MWCs within
the existing and projected population
Baseline emission estimates were
developed for each model plant and
control alternatives were applied to each
model to estimate the potential for
reduction of emissions from baseline
levels. Costs of control alternatives were
estimated to permit calculation of the
cost effectiveness of control options.
Performance Data/Rationale
This report summarizes the perform-
ance data and supporting rationale that
were used to establish the baseline
emission estimates for 12 MWC model
plants. Each model represents a group of
MWCs that will be regulated by the
NSPS. Descriptions of the model plants
are contained in a companion report. The
baseline performance levels were
established using the available emissions
data base for MWCs or, in cases where
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little or no data existed, engineering
judgment. The baseline emissions are
expressed as unabated concentrations
measured prior to treatment by add-on
flue gas cleaning equipment. The
unabated emissions represent
performance levels that result from the
application of good combustion practice
(GCP), which is expected to be in place
at all new MWCs. GCP requires that
specific design, operation, control, and
monitoring features be in place to
optimize the combustion process, thus
minimizing emission of trace organics
and carbon monoxide (CO). The
necessary components of GCP were
originally defined in EPA's Report to
Congress on MWC. The data used to
establish baseline emissions are limited
to data available from the newest facilities
in the MWC population. This report
summarizes the design and operating
features of the combustors in the data
base and evaluates the extent to which
recommended design and operating
components of GCP are in place at each
plant.
Model Plants
Using projections of the future MWC
population, 12 model plants were
developed to represent the majority of
combustor classes that would be
regulated by the NSPS. The models
included three mass burn waterwalt
MWCs, one mass burn refractory wall
MWC, one rotary waterwall MWC, one
modular excess air MWC, two modular
starved air MWCs, two refuse-derived-
fuel (RDF) fired spreader stoker MWCs,
one RDF bubbling fluidized bed MWC,
and one RDF circulating fluidized bed
MWC. Information provided for each
model plant included unit size, number of
combustors per site, annual operating
hours, electric generating status (all
models were assumed to produce
steam), and fuel type (either unprocessed
municipal solid waste, RDF, or a mixture
of RDF and wood waste).
Emission Estimates
Baseline uncontrolled emissions were
estimated for three air pollutants:
polychlorinated dibenzo-p-dioxins and
dibenzofurans (CDD/CDF), CO, and
particulate matter (PM). The CDD/CDF
data included in the baseline
determination were limited to test results
available to EPA. Six sets of data were
available for mass burn waterwall MWCs
and three data sets for modular excess
air and modular starved air units. No
CDD/CDF data were available from rotary
waterwall units, and only one or two data
sets for each of the other technologies.
Therefore, engineering judgments were
used to some extent to assign baseline
CDD/CDF emissions. The baseline
CDD/CDF concentrations ranged from 20
ng/dscm, corrected to 7% 02, for the
bubbling fluidized bed model plants to
1000 ng/dscm, corrected to 7% O2, for
RDF spreader stoker model plants. Mass
burn waterwall and modular excess air
model plants were assigned baseline
CDD/CDF emissions of 200 ng/dscrri|
corrected to 7% 02. Mass burn refractory
wall, mass burn rotary waterwall, and
modular starved air model plants were
assigned baseline CDD/CDF emissions ol
300 ng/dscm, corrected to 7% 02
Finally, RDF circulating fluidized bee
model plants were assigned a baseline
CDD/CDF emission level of 400 ng/dscm
corrected to 7% 02- Baseline CC
emissions ranged from 50 to 100 ppm, 4
hour average, corrected to 7% O2 for al
models. Baseline PM emissions rangec
from 0.1 gr/dscf (230 mg/dscm) to <
gr/dscf (9200 mg/dscm), corrected to 7°/>
02. The lowest PM emissions wen
assigned to modular model plants ant
the highest PM emissions were from RDf
spreader stokers and FBC model plants
The remaining models were assignei
baseline PM emissions of 2 gr/dscf (460i
mg/dscm). The different baseline P^
emission rates reflect inheren
performance characteristics of eac
model plant type (e.g., low primar
chamber gas velocities result in low PI
entrainment for modular MWCs, whil
semisuspension firing of RDF in spreade
stoker boilers results in higher Pf
carryover).
The data presented in this report wer
used to establish performance estimate
for model plants in the NSPS regulator
development effort, thus providing
baseline for assessing emissio
reductions and costs of add-on contn
alternatives.
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P. J. Schindler is with Energy and Environmental Research Corp., Durham, NC
27707.
James D. Kllgroe is the EPA Project Officer (see below)
The complete report, entitled "Municipal Waste Combustion Assessment:
Combustion Control at New Facilities," (Order No. PB90-154 9231 AS; Cost:
$17.00, 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:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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