DEVELOPMENT OF GOOD COMBUSTION PRACTICE
FOR MUNICIPAL WASTE COMBUSTORS*
James D. Kilgroe
U.S. Environmental Protection Agency
Air and Energy Engineering Research Laboratory
Research Triangle Park, NC 27711
W. Steve Lanier and T. Rob von Alten
Energy and Environmental Research Corporation
Durham, NC 27707
ABSTRACT
The U.S. Environmental Protection Agency is developing new air pollution rules for all
new and existing municipal waste combustors (MWCs). These rules require all MWCs to use
good combustion practice (GCP). The goals of GCP are to maximize furnace destruction of
organic pollutants, limit the relative amount of paniculate matter (PM) carried out of the combustor
with flue gases (PM carryover), and ensure that the PM control device is operated at temperatures
which do not result in the formation of excessive amounts of chlorinated dibenzo-p-dioxins and
chlorinated dibenzofurans (CDD/CDF). This paper summarizes the rationale for EPA's GCP
strategy. This strategy incorporates the use of three continuous compliance parameters: carbon
monoxide (CO) emissions, furnace steam load, and PM control device inlet temperature.
Experimental data are provided to show that furnace emission of organics is correlated with CO
concentration, the amount of PM carryover (which is related to load), and temperature at the PM
control device inlet. The relationships between the GCP compliance parameters and other
combustion parameters which are necessary ingredients of good combustion (uniformity of waste
feed, the amount and distribution of excess air, combustion temperature and residence time, and
mixing of combustion air with thermal decomposition products) are also discussed.
INTRODUCTION
In 1987, EPA completed a comprehensive study of municipal waste combustion which
included evaluation of the health and environmental risks associated with MWCs and an
assessment of the criteria and hazardous air pollutant emission reduction potential of both
combustion process controls and flue gas cleaning technologies.^ Concurrent with the
publication of this study EPA announced its intention to propose new rules to control air pollution
emissions from MWC facilities.^ One of the major driving forces behind this announcement was
public and scientific concerns related to MWC emissions of trace organics, especially CDD/CDF.
Prior to the announcement of proposed rule making, the Office of Air Quality Planning and
Standards (OAQPS) issued operational guidance to EPA's Regional Offices concerning approval
of applications for permits for new facilities.7 These guidelines, which applied to facilities subject
to prevention of significant deterioration or non-attainment new source review, specified that all
new incinerators use GCP and the appropriate flue gas cleaning technology to ensure adequate
control of air pollution emissions. Although the criteria for achieving good combustion were not
This paper has been reviewed in accordance with the U.S. Environmental Protection
Agency's peer and administrative review policies and approved for presentation and
publication.
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defined in the operational guidance, the Regional Offices were referred to recommendations for
good combustion provided in the report, "Municipal Waste Combustion Study: Combustion
Control of Organic Emissions".4
\
Shortly after publication of the 1987 recommendations, work was begun to develop GCP
recommendations that would be applicable to all existing and new MWC facilities.8-9 This work
resulted in the formulation of the revised GCP strategy described in this paper. It comprises the
technical basis for EPA's rules for GCP at MWC facilities.10"12 This paper includes a discussion
of the origins of organic emissions, the 1987 recommendations, the components of GCP,
surrogates for measuring total organics, the strategy for controlling organic emissions, the method
of specifying numerical values for continuous parameters, and a summary of EPA rules for GCP.
DISCUSSION
Background
The objective of GCP is to minimize stack emissions of trace organics and the amounts of
these organics in collected fly ash. Organic compounds such as CDD/CDF may originate in the
waste but it is unlikely that they will pass through the incinerator or combustor undestroyed.13
They may also originate in the high temperature regions of the furnace from thermal decomposition
products which are not completely oxidized due to insufficient combustion air, mixing,
temperature, or residence time.4-14-15 Or, they may originate from reactions on the surface fly ash
downstream of the combustion chamber.15'21
The recommendations contained in the 1987 report on the combustion control of organics
(1987 Recommendations) were an attempt to summarize the best combustion practices as applied to
modern MWCs.4 They were intended to be a summary of "current knowledge" and were not
intended to be regulatory requirements. The recommendations applied only to mass bum, refuse
derived fuel (RDF), and starved air combustors. They were predicated on the belief that optimum
combustion within the furnace would minimize stack emission of organics, and they dealt solely
with combustion conditions within the furnace. The relative importance of low temperature
formation of organics was unknown and none of the 1987 Recommendations dealt explicitly with
low temperature (i.e., downstream) formation.
The 1987 Recommendations were classified into three elements: design, operation/control,
and verification (monitoring). The rationale for these three elements was that:
1. MWCs must be designed in a manner that allows operation at conditions that
minimize organic air emissions.
2. MWCs must be operated within an envelope dictated by the design of the
combustion system, and controls must be in place to prevent operation outside of the
established operation envelope.
3. The performance of the combustion system must be verified by way of compliance
testing through continuous monitoring of key operating parameters such as combustion air
flow, gas temperature, carbon .monoxide (CO) concentrations, and oxygen (02)
concentrations.
Design recommendations included: the capability of achieving a minimum temperature of
980°C at fully mixed conditions to ensure thermal destruction of organics; the ability to control the
distribution of underfire air as needed because of different combustion air requirements at different
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locations; the specification of a minimum overfire air capacity to ensure that sufficient overfire air is
available for mixing; and requirement that the overfire air system be capable of adequate penetration
and coverage of the furnace cross section.
Operating/control recommendations included: the specification of oxygen concentrations in
the flue gas as needed to ensure proper levels of combustion air (excess air); a limitation on the
range of operating load as needed to maintain minimum combustion intensities and avoid excess
waste burning rates; the use of an auxiliary fuel to avoid excess organic emissions during start-up;
and the use of auxiliary fuel as a corrective measure for low furnace temperatures or high CO
concentrations.
Verification recommendations included continuous monitoring for control of: oxygen
concentrations in the flue gas; CO concentrations in the flue gas (no greater than 50 ppm on a 4-
hour average); and a minimum combustion gas temperature of 980°C at fully mixed conditions. If
a combustor exhibited excessive CO emissions during start-up tests, the use of in-furnace CO
profiles was recommended for correcting combustion air distributions.
GCP Components
Recommendations for GCP evolved as the results of additional investigations on the
formation, destruction, and control of organics became available. These investigations included:
field test projects sponsored by EPA and others;21'35 laboratory research sponsored by EPA;36'39
discussions with researchers in the U.S., Canada and Europe; and engineering analyses of all
available field test data.8-9-10'40"43 The engineering analyses included attempts to validate the 1987
Recommendations by comparing available field test data on organic emissions with the combustion
parameters measured during performance and compliance testing of MWCs.8-9 These attempts
were only partially successful due to the paucity of combustion measurements made during most
field test projects. The results of initial work in development of GCP for MWCs are discussed in
three previous papers.15'44'45
During the initial work on the development of GCP it became apparent that waste feed
conditions and the low temperature formation of organics must be controlled to limit organic
emissions. The 1987 Recommendations were therefore expanded to incorporate components
dealing with feed conditions and low temperature formation. GCP requirements were also
developed for types of combustors that were not covered by the 1987 Recommendations.
The reformulation of the 1987 Recommendations resulted in the specification of seven
GCP components: the Amount and Uniformity of Waste Feed, Combustion Temperature and
Residence Time, the Amount and Distribution of Combustion Air, Mixing, PM Carryover,
Downstream Temperature, and Combustion Monitoring and Control.10'15
Amount and Uniformity of Waste Feed: The rate of waste feed will affect combustion
temperature and gas residence times within the furnace. Combustion stability can be affected
significantly by sudden changes in waste composition or feeding characteristics. During steady
state operation, fuel feed rates and combustion air flows are established to provide local and overall
stoichiometries and system temperatures commensurate with operation at normal conditions,
usually the design load as determined by steam flow rate.
Variation in waste volatile matter content, moisture content, feed rate, size distribution, or
distribution pattern in the furnace will result in rapid changes in combustion air requirements and
corresponding changes in local stoichiometry. Surges of highly volatile waste can rapidly deplete
local oxygen concentrations, causing formation of fuel-rich gas pockets that may escape the
furnace without being adequately oxidized. These conditions are generally accompanied by
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elevated concentrations of organics and CO. Extreme variations in the waste heating value and
moisture content can affect system temperatures as they impact the heat input to the combustor and
the total heat capacity of the combustion products, respectively.
The amount and uniformity of waste feed must be controlled to ensure operation at the
desired steady state levels and avoid combustion excursions which result in emission of increased
amounts of organic pollutants.
Combustion Temperature and Residence Time: Temperature is a consequence of
combustion conditions as determined by the waste calorific value, moisture content, ash content,
and the combustion gas heat loss rate. Local combustion temperatures are important because they
determine the rate of thermal decomposition and the rate of chemical reactions. Low furnace
temperatures or inadequate residence times will result in increased furnace emission of organics.
Organics in MWC flue gases may exist as gas-phase compounds or entrained particles.
The entrained particles may be sooty particles (condensed products of incomplete combustion) or
unburned material such as the skeletal carbon structure of devolatized paper. Destruction of
organics in MWCs occurs by thermal degradation, chemical attack by flame radicals, and by the
final oxidization of OH and CO to HiO and COi-
When gas-phase organic compounds at normal combustion temperatures pass through
active flame zones containing oxygen they are chemically destroyed within a few milliseconds.
Gas-phase organic compounds which do not contact oxygen can be thermally degraded within
seconds if temperatures are sufficiently high. Solid-phase organic particles may require long
residence times at high temperatures before they are completely destroyed. The time to burn
particles depends on the temperature, particle size, and availability of oxygen. Times for burnout
increase with increasing particle size and decreasing temperature. Time-temperature requirements
for destruction of gas-phase organics may not be sufficient to ensure destruction of solid-phase
organics.
Amount and Distribution of Combustion Air: The proper amount and distribution of
combustion air are essential for efficient combustion. The total amount of air needed for complete
combustion at a given waste burning rate includes a stoichiometric requirement and an excess air
requirement. The stoichiometric air requirement is the average amount needed to completely
oxidize all the waste thermal decomposition products. Excess air can be considered to be an
additional amount to account for (1) short term variations in waste feed properties and (2) the
inability to exactly match combustion air requirements with combustion air supplies at all locations.
In refractory walled incinerators, high levels of excess air are used to limit grate temperatures and
control slagging. Excess air levels may also be controlled to limit NOX emissions.
It is also important to distribute combustion air to under- and overfire locations where it is
needed to satisfy local combustion requirements. The distribution of primary (underfire) air is
essential in maintaining bed burning stoichiometry and good waste (char) burnout. Optimal
conditions for primary air control will depend on the combustor technology. For example in
conventional mass bum waterwall units, primary air control is achieved by the use of multiple
underfire air plenums, each with separate controls. The distribution of underfire air to each grate
section is varied to accomplish drying, burning, or burnout. In starved air combustors, sub-
stoichiometric amounts of underfire air are provided in the primary combustor to avoid clinker
formation and limit paniculate emissions. RDF combustors can be designed to meet the underfire
air requirement by the use of multiple underfire air zones or by controlling the manner in which
RDF is distributed on the grate.
In many types of combustors, secondary or overfire air is needed to adjust local
stoichiometries to complete oxidization of bed thermal decomposition products which are fuel-rich.
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Overfire air is also important in controlling combustion of the fuel bed. In burning fuel beds the
local volatilization rate and bed burning rate are dependent on the local underfire air rate. An
increase in underfire air rate to supply air to the overfire region, as needed to complete combustion,
may result in increased bed burning rates, increased volatilization rates, and increased entrainment
of particulates. Addition of combustion air above the fuel bed avoids these problems, provides
combustion air to oxidize organics, and provides flexibility in controlling the combustion process.
Mixing: Intimate mixing of fuel and air is widely recognized as a requirement for complete
combustion. Poor mixing produces local stoichiometries which prohibit complete destruction of
organics even at equilibrium conditions. Combustion processes typically exhibit a high degree of
mixing associated with the turbulence of the thermally expanding products of combustion. In
modem MWCs this inherent mixing is abetted by one or more techniques, including the use of (1)
jets of combustion air, recirculated flue gas, or steam and (2) furnace geometry or configuration.
Many designs use both configuration and jets to achieve good mixing.
Furnace geometry or configuration can be used to direct combustion gas flows and enhance
mixing of combustion air and thermal decomposition products. Common design techniques for
enhancing mixing are the use of cross-sectional area changes, flow baffles, and wall-turns. Some
designs incorporate two combustion chambers. Changes in cross-sectional flow areas and flow
direction between the chambers enhance mixing effects. Other designs use baffles or bull noses to
improve mixing. •
Overfire air jets are one of the most common techniques used to enhance mixing.
Recirculated flue gas, used primarily to control NOx emissions, is occasionally used. Steam jets
are almost never used. Important design considerations associated with jets are the number and
location of jets and jet momentum. It is important to get good jet penetration (momentum) and
lateral coverage (number of jets) at the injection cross-section. Most conventional waterwall mass
burn combustors use overfire air jets on both the front and rear walls. In these designs there is an
arch over the burnout grate. This arch reflects radiant heat back into the refuse bed and directs
combustion products from the burnout grate back to the middle portion of the furnace (entrance to
the upper furnace) where they can mix with gases from the burning and drying grates. Overfire air
jets are typically placed at the entrance to the upper furnace where they are most effective in
adjusting lower furnace stoichiometries and mixing with thermal decomposition products from the
lower furnace.
MWC manufacturers typically rely on experience and flow modeling to achieve good
mixing. Poor mixing generally results in high emission of trace organics and CO. Good mixing
is a function of many design and operating variables. While the principles of good mixing can be
defined, there is currently no known combination of design and operating parameters which can a
priori guarantee good mixing. However, CO can be used as an indirect measure to ensure that
satisfactory mixing is being achieved in MWCs.
PM Carryover: Particulate matter carried out of the furnace with flue gases (PM carryover)
can result in formation of CDD/CDF and other chloro-organics downstream of the combustor.
Limiting PM carryover will help to limit downstream formation of organics.
The results of field tests have shown that CDD/CDF and other organics are formed as flue
gases and fly ash pass through the combustion system and flue gas cleaning
equipment. 10,21,30,32,33,34,35 LOW temperature formation, called de novo synthesis, is believed
to involve reactions on the surface of fly ash at temperatures ranging from approximately 150 to
450°C.16-18'21 The rate of formation depends on the flue gas composition (oxygen and water
content), fly ash composition (carbon and metal content), and temperature. Increased amounts of
fly ash result in increased reaction sites for the formation'of organics. Figure 1 shows the strong
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correlation between the amount of PM carried out of a mass burn waterwall combustor and stack
emission of CDD/CDF.
PM carryover is dependent on combustion conditions, waste properties, and combustor
type. Fundamentally, the tendency of a particle to be entrained in an upward flowing gas stream is
a function of the particle size, shape, and density and the gas velocity around the particle. The
entrainment of particles will increase with increased flue gas flow rates and specifically increased
underfire air flow rates. Thus PM entrainment tends to increase with decreasing waste particle
size, increasing waste burning rates (load), increasing excess air rates, and increasing underfire air
rates. Conventional mass burn combustors have higher PM entrainment rates than starved air
combustors because of the lower relative amount of air supplied as underfire air. RDF spreader
stokers tend to have higher rates of particle entrainment due to the semi-suspension mode of
combustion employed and because RDF contains more small light particles.
Downstream Temperature: The rate of downstream CDD/CDF formation in MWC systems
is highly dependent on temperature. Control of the time/temperature history of flue gas and PM
leaving the furnace is an important component in limiting the amount of organics in emitted stack
gases and collected fly ash.
Laboratory experiments have shown that de novo synthesis of CDD/CDF occurs at
temperatures ranging from approximately 200 to 450°C.15'18 Maximum formation rates are
observed at approximately 300°C.16'18 The results of field tests lead to the conclusion that
paniculate control devices which hold large amounts of collected fly ash can act as chemical
reactors which generate CDD/CDF and other trace organics. Tests on mass burn waterwall and
starved air modular combustors have shown lower flue gas concentrations of CDD/CDF at the
electrostatic precipitator (ESP) inlet than at the outlet (formation within the ESP) for temperatures
greater than approximately 230°C (see Figure 2).10>15 Tests on a mass refractory combustor have
shown CDD/CDF formation in an ESP at temperatures as low as 150°C.21 Pilot scale combustor
tests have also shown that CDD/CDF can be formed in fabric filters (FFs).20 It is therefore
important to avoid PM control device operation at temperatures that result in high CDD/CDF
formation rates.
Combustion Monitoring and Control: The last GCP component, combustion monitoring
and control, provides a means of integrating system design and operation to provide for
achievement of GCP on a continuous basis. The relationships between waste feed rate and the
amount and distribution of combustion air that are needed to provide a given heat release rate (load)
while maintaining efficient combustion with minimal emission of organics are complex. Organic
emissions can increase substantially during periods of upset or "off-spec" operation, and operation
under these conditions should be minimized. MWCs must be operated according to design
specifications, and controls must be incorporated into the system design to respond to changes in
steam load, temperatures, 62 concentrations, and CO concentrations that result in changing waste
properties. MWCs must also be capable of starting up, shutting down, and changing load from
one level to another while maintaining satisfactory combustion conditions.
To adequately control combustion conditions to minimize emission of organics, MWCs
should be capable of continuously monitoring and controlling: waste feed rates, combustion air
flow rates, steam load, temperatures in the furnace, the temperature at the entrance to the PM
control device, flue gas concentrations of O2, and flue gas concentrations of CO.
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GCP Application Strategy
Early in the development of new rules for controlling air pollution emissions from MWC
facilities, EPA decided to control MWC organic emissions, MWC metal emissions, and MWC
acid gas emissions. The total concentrations of CDD/CDF were selected as an indicator (surrogate)
for measuring the control of MWC organics. MWC organics were to be controlled by the use of
GCP and appropriate flue gas cleaning techniques.
The strategy for implementing GCP as a method of regulating organic emissions was based
on a number of considerations:
(a) The implementing strategy should ensure the control of all organics emissions.
It should not focus solely CDD/CDF.
(b) The control of emissions should be verifiable on a continuous basis.
(c) Performance requirements are preferable to design or operating specifications.
(d) Implementation (monitoring and control) costs should be reasonable.
GCP was implemented to achieve two basic objectives: to maximize furnace destruction
and to minimize downstream formation of organics. Maximizing furnace destruction of organics
would also ensure that trace organics in the feed are destroyed.
After a careful review of the components of GCP, it was concluded that the two major
technical objectives of GCP could be achieved by continuously monitoring and controlling (1) the
flue gas concentration of CO, (2) steam load (a surrogate for PM carryover), and (3) temperature at
the inlet of the PM control device. These three variables were therefore selected as "continuous
compliance parameters" to demonstrate continuous control of "MWC organic" emissions.
The use of CO as a single indicator for furnace destruction is not consistent with the 1987
Recommendations, in that O2 concentrations, combustion temperature, load ranges, and the use of
an auxiliary fuel are not prescribed. There are several reasons for this difference. A major reason
was the desire to avoid the specification of design and operating conditions whenever possible.
Performance standards are preferable to equipment operating specifications. A second reason was
the inability to define the limits or ranges of conditions for all combustion parameters for all the
various types of combustors employed in the U.S. For example, combustion temperatures and
flue gas oxygen concentrations are important indicators of combustion conditions which should be
measured at MWC facilities. While these parameters should be measured at all facilities, they
should be used by the operators for monitoring and control of the combustion process. Their use
as a GCP compliance parameter could place improper limitations on combustor operation and result
in problems such as slag buildup. CO and total hydrocarbon (THC) concentrations in flue gas are
more appropriate indicators of combustion conditions which result in the furnace destruction of
organics.
Furnace Destruction of Organics: Gas-phase CDD/CDF and other organics are believed to
be thermally destroyed in active combustion zones at temperatures ranging from 730 to 980°C.4
However, measurements made at high temperatures (590 to 980°C) in MWC furnaces have shown
the presence of significant quantities of CDD/CDF (250 to 5000 ng/dscm).21-34.35 Depending on
operating conditions, the CDD/CDF and other organics in combustion products may either increase
or decrease as the combustion products pass through heat extraction and flue gas cleaning
equipment. Combustion conditions which maximize the furnace destruction of organics will
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minimize organies leaving the combustor and reduce the potential for downstream formation of
CDD/CDF.
Ideally, verifying the furnace destruction of organies on a continuous basis would involve a
technique for monitoring the total amount of organies leaving the furnace. Since no such technique
exists for continuously monitoring total organies, it was decided to continuously monitor the
furnace flue gas CO concentration. Field and laboratory experiments have shown that low
concentrations of CO are associated with low concentrations of organies in flue gases, and high
concentrations are associated with high concentrations of organics.29-31 While CO is not a direct
measure of total organies it is a good indicator of the combustion conditions which characterize
combustion efficiency. An alternative approach would have been to monitor total (gas-phase)
hydrocarbons with a continuous emission monitor. However, field tests had shown CO to be a
more sensitive indicator of combustion conditions and it was therefore selected as an indicator to
characterize furnace destruction of organies. ^
The adequacy of CO for demonstrating combustion efficiency in destroying organies was
evaluated by considering the effects of a failure to satisfy each of the GCP components dealing
with furnace destruction of organies. From theoretical analyses and combustion test results it can
be concluded that CO emissions will increase if:
(a) Excess amounts of waste are fed to the combustor or excessive variations in waste
uniformity cause combustion upsets. Combustion tests at the Quebec City mass burn
incinerator and the Mid-Connecticut RDF combustion facility exhibited increased CO
emissions at high loads (high bum rates).26-29-31 Variations in waste feed conditions were
found to be major causes of high CO emissions at fluidized bed combustion and RDF
spreader stoker facilities .9-46
(b) Combustion temperatures are too low or combustion gas residence times at high
temperatures are too short. Combustion tests at the Quebec City facility exhibited higher
CO emissions at low combustion temperatures than for normal combustion temperatures.31
(c) An improper amount of combustion air is used or there is poor distribution of
combustion air. Tests with poor combustion air distribution resulted in higher than normal
CO concentrations during combustion tests at the Quebec City and Mid-Connecticut
facilities.26-29'31
(d) Waste thermal decomposition products and combustion air are improperly mixed in
the high temperature regions of the furnace. CO concentrations during tests at the Mid-
Connecticut facility were very sensitive to overfire air mixing conditions,2^ 29
The effectiveness of CO as an indicator for the furnace destruction of organies can be
illustrated by the results of tests at the Mid-Connecticut RDF combustion facility. The correlation
between average CO and CDD/CDF concentrations at the spray dryer inlet (furnace emissions) for
13 tests is shown in Figure 3. These 13 tests represent a matrix of operating conditions designed
to produce a wide range of good (CO<200 ppm) and poor (CO>200 ppm) combustion conditions.
The primary combustion variables were load, under-to-overfire air ratio, and overfire air
distribution. The CO concentration at the spray dryer inlet provided the best single parameter
correlation for CDD and CDF concentrations at the same location. It provided the second best
correlations (after THC concentration) for chlorophenols, chlorobenzenes, and polycyclic aromatic
hydrocarbons.29 Multiple regression analyses using monitoring variables (combustion gas
properties) indicated that two to four of the following variables best explained variations in flue gas
concentrations of organies: CO concentrations, THC concentrations, NOX concentrations, furnace
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temperature, and Cl concentrations (CDF only). Multiple regression analyses using combustion
control variables indicated that the following control variables best explained variations in organic
concentrations: total undergrate air flow, rear wall overfire air flow, total overfire air flow, steam
flow rate (load), and RDF moisture content.2^ These and other tests provide ample evidence that
flue gas concentration of CO is a good indicator of the furnace destruction of organics. ^
Downstream Formation of Organics. CDD/CDF and other organics can be formed
downstream of the furnace by de novo synthesis reactions on the surface of fly ash. The amount
formed is believed to be proportional to the amount of fly ash and the time individual particles
reside at temperatures ranging from about 150 to 450°C.
The results of tests at the Quebec City Urban Community Center Incinerator and other
facilities have shown that CDD/CDF concentrations in the flue gas are strongly correlated with the
amount of fly ash entrained in the combustor flue gases (see Figure 1). The relative amount of fly
ash in the flue gas depends on the type of combustion technology and specific combustion
parameters such as under-to-overfire air ratio and total volumetric flow of flue gases. Excessive
amounts of fly ash, relative to normal conditions, are entrained if the rate of waste burned exceeds
the design capacity of the combustor. Higher volumetric flue gas flow rates and increased fly ash
entrainment result from operation above the design load. Since there are no commercially available
systems for measuring the amounts of entrained fly ash or validated techniques for continuously
measuring flue gas flow rates, it was concluded that boiler load as measured by steam flow rate
could be used to avoid operation at conditions that are associated with excessive PM carryover.
Flue gas cleaning devices for the dry collection of PM, such as ESPs, retain large amounts
of fly ash that can serve as a source of reactions which form CDD/CDF and other organics. A
large fraction of the CDD/CDF entering an ESP is probably associated with fly ash that can be
collected. However accumulated fly ash within the ESP can serve as a source for the de novo
synthesis of CDD/CDF. Newly formed CDD/CDF can remain with the collected fly ash, it can be
re-entrained along with the associated fly ash, or it can be desorbed into the flue gas stream as a
vapor. The amount formed within the PM device will depend primarily on the rate at which fly ash
and organic precursors enter the device, the flue gas composition (C>2 and water vapor), the length
of time fly ash is retained (amount accumulated), and the temperature. If other factors are relatively
constant, then the temperature at which the PM control device is operated will play a dominant role
in determining the CDD/CDF collection, formation, and stack emission rate. At inlet temperatures
near 300°C, formation rates will dominate and CDD/CDF outlet concentrations will generally
exceed CDD/CDF inlet concentrations. At some lower temperatures, the inlet and outlet
concentrations will approach a balance and, as the inlet temperature is further reduced, formation
rates will become negligible or cease.
In tests conducted by EPA to investigate the effects of ESP inlet temperature on CDD/CDF
collection, formation, and emission rates, it was found that measurable rates of formation (net
increases of CDD/CDF concentrations across the ESP) occur at temperatures as low as 150°C (see
Figure 4).21 High rates of formation occur at 300°C and intermediate rates occur at 200°C. In tests
at other facilities it has been found that net capture and formation rates balance at approximately
230°C [i.e., the mechanisms which control formation and stack emission of CDD/CDF are not
dominated by PM control operating temperature (see Figure 2)]. Although the rates of downstream
formation are dependent on the design and operating conditions at each facility it can be generally
concluded that limiting the PM control device to 230°C or less will avoid temperatures which
maximize formation rates of CDD/CDF.
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Numerical Values for Continuous Compliance Parameters
Recommendations on numerical values for the GCP continuous compliance parameters
were developed and the resulting values were published along with other proposed rules for MWC
facilities on December 20, 1989.10-u These proposed rules were applicable to new and existing
MWCs regardless of size.
The proposed requirements were applicable to nine specific types of combustors: waterwall
mass burn, refractory mass burn, rotary waterwall, starved air modular, excess air modular, RDF
spreader stoker, bubbling fluidized bed, circulating fluidized bed, and coal/RDF co-fired
combustors. The proposed emission limits for these combustors ranged from 50 to 150 ppm (at
7% Oi), depending on the combustor type. All emission limits were to be based on a 4-hour block
averaging time, and the emission limits for a given type of combustor were the same for new and
existing units. These CO emission limits and associated averaging times were based on EPA field
test experience and on an evaluation of short and long term emission data sets from commercially
operating MWCs.10 The proposed rules also prohibited operation in excess of 100 percent of the
maximum MWC unit load (1-hour avg.) and limited the temperature at the inlet to the PM control
device to a maximum of 230°C (4-hour avg.). The proposed rules for load and downstream
temperature were the same for all types of combustors and for both new and existing combustors.
MWCs which do not generate steam were exempt from the load requirement.
The proposed rules also required certification of chief facility operator and shift supervisors
by the American Society of Mechanical Engineers (ASME). The development and use of a training
manual specific to each site was also required.] 1
Based on public comments and further evaluations of technical achievability and likely cost
impacts, revisions were made to the proposed rules and final rules were promulgated on February
11, 1991.47-12 The promulgated rules applied only to large new units, large existing units, and
very large existing plants. Although rules had been proposed for small new plants and small
existing plants, rules for small new units were not promulgated because of provisions in the
November 1990 Clean Air Act Amendments.48 A summary of the promulgated GCP requirements
is presented in Table 1.
Important clarifications and changes between the proposed and promulgated GCP are:
CO Emissions: The proposed CO emission limits for both new and existing RDF spreader
stokers were 150 ppm with a 4-hour averaging time. The promulgated CO standard for new units
was 150 ppm on a 24-hour averaging time, and the promulgated guideline for existing units was
200 ppm on a 24-hour average.12 The changes in the CO rules resulted from statistical evaluations
of new long term data sets from RDF spreader stokers.46 CO emissions from RDF spreader
stokers are inherently more variable than from mass burn or modular combustors. Semi-
suspension firing of a finer sized waste results in a greater dependency of short term CO emissions
on variations in waste properties. The longer averaging time in the promulgated rules was to
account for the inherently higher sensitivity of RDF combustors to feed conditions. The higher
emission limit for existing units was to due the difficulty of controlling emissions in some units.
Most notably, some small RDF combustors have relatively small furnaces and only two RDF
feeders. While these units have state-of-the art feeders, they are much more sensitive to variations
in waste feed conditions than larger units with more feeders and greater furnace volumes.
The proposed CO emission limit for both new and existing rotary waterwall combustors
was 150 ppm on a 4-hour average. The promulgated standard for new units was 100 ppm on a
24-hour average and the promulgated guideline for existing units was 250 ppm on a 24-hour
10
-------
average.12 A statistical evaluation of new long term CO emission data sets for rotary waterwall
combustors indicated that the most recently constructed units are capable of achieving a CO
emission limit of 100 ppm (24-hour average) and that older units are capable of achieving a CO
emission limit of only 250 ppm (24-hour average).4^
Steam Load Requirements: -r^ proposed rules would have precluded operation above 100
percent steam load on a 1-hour averaging time. The promulgated rules preclude operation above
110 percent of the maximum average load level (4-hour average), as demonstrated during the most
recent CDD/CDF compliance test.12 The increase from 100 to 110 percent was to account for
variations in steam load.49 For example, a unit operating at an average steam load of 100 percent
of maximum rated capacity (MRC) might typically operate at between 90 and 110 percent of MRC.
The average maximum operating load is to be defined by the average load recorded during the most
recent CDD/CDF compliance test and, since each CDD/CDF test takes about 4 hours, the load
averaging time was changed to 4 hours for consistency.
Downstream Temperature: The proposed rules specified a maximum temperature of 230°C
(450°F) at the PM control device inlet. The promulgated rules stated that the operation of each
MWC is to be controlled so that the flue gas temperature at the primary PM control device inlet
does not exceed 17°C (30°F) above the maximum temperature demonstrated on the most recent
CDD/CDF compliance test.12 This revision explicitly couples the permitted maximum PM control
device operating temperature to conditions which are shown to avoid excess CDD/CDF
emissions.5^ Existing MWCs which now operate their PM control devices above 230°C (450°F)
and which can comply with CDD/CDF emission requirements would not be required to reduce
downstream temperatures as an organic emission control measure. The revision also ensures that a
facility does not operate at a low PM control device operating temperature such as 150°C during
compliance tests and then operate at 230°C during other time periods.
Start-up and Shutdown: Several comments were made on the proposed rules regarding
exemption of GCP requirements during periods of start-up, shutdown, and malfunction and the
use of auxiliary fuels during these periods.47-51 The final rules provided a 3-hour exemption from
the GCP requirements during start-up, shutdown, and malfunction. An evaluation of CO
emissions from several facilities indicated that the CO emission requirement could be met if
auxiliary fuel is used and a 3-hour exemption is allowed for each start-up and shutdown period.51
The use of auxiliary fuels is not explicitly required since all units will have to use an auxiliary fuel
to preheat the unit prior to start-up (the beginning of waste feed to the combustor) in order to
comply with the CO emission limit in the first time period after the completion of start-up.
Certification: The proposed rules required certification of the chief facility operator and
shift supervisors by ASME. The final rules also allow certification by equivalent state-approved
certification programs.12
CONCLUSIONS
Organic compounds such as CDD/CDF may originate in the waste but it is unlikely that
they will pass through the incinerator or combustor un-destroyed. They may also originate in the
high temperature regions of the furnace from thermal decomposition products which are not
completely oxidized due to insufficient combustion air, mixing, temperature, or residence time.
Or, they may originate from reactions on the surface fly ash downstream of the combustion
chamber.
11
-------
Combustion control has traditionally been concerned with conditions in the high
temperature regions of the furnace. The discovery of low temperature reactions on the surface of
fly ash requires control of the time/temperature history of combustion products as they pass
through the combustor and flue gas cleaning devices.
GCP can be used in MWCs to aid in continuous control of trace organic emissions. The
principles of good combustion are embodied in seven GCP components. Four of the components
deal with the furnace destruction of organics, two deal with low temperature formation of organics,
and one deals with continuous monitoring and control of combustion parameters. The components
of GCP must be met individually and collectively to ensure combustion control of organic
emissions.
Maintaining combustion conditions to simultaneously satisfy all GCP components is a
complex and difficult task, requiring substantial engineering design and operating expertise.
Definition of the envelope of combustion operating parameters which lead to good combustion has
to be experimentally determined for each type of combustor by the owners/operators of the facility.
Conditions which relate to the emission of trace organics can be monitored and controlled
by the use of three parameters: the CO concentration of flue gases, steam load, and the temperature
at the inlet to the primary PM control device. CO is a good indicator of the furnace destruction of
organics. Steam load can be used to avoid operation at conditions which result in excessive PM
carryover. Temperature at the inlet to the PM control device can be used to limit organic reaction
rates on the surface of collected fly ash.
REFERENCES
1. Greene, S., Municipal Waste Combustion Study: Report to Congress, EPA/530-SW-87-
021a (NTIS PB87-206074), June 1987.
2. Cleverly, D.C., Municipal Waste Combustion Study: Assessment of Health Risks
Associated with Municipal Waste Combustion Emissions, EPA/530-SW-87-021g (NTIS
PB87-206132), September 1987.
3. U.S. EPA, Municipal Waste Combustion Study: Emission Data Base for Municipal Waste
Combustors, EPA/530-SW-87-021b (NTIS PB87-2060882), June 1987.
4. Seeker, W.R., Lanier, W.S., and Heap, M.P., Municipal Waste Combustion Study:
Combustion Control of Organic Emissions, EPA/530-SW-87-02Ic (NTIS PB87-206090),
June 1987.
5. Sedman, C.B. and Brna, T.G., Municipal Waste Combustion Study: Rue Gas Cleaning
Technology, EPA/530-SW-87-021d (NTIS PB87-206108), June 1987.
6. Assessment of Municipal Waste Combustor Emissions Under the Clean Air Act, U.S. EPA
Advance Notice of Proposed Rulemaking, 52 CFR 25399, July 7, 1987.
7. Emison, G.A., 1987. Memorandum to EPA regional offices: Operation guidance on
control technology for new and modified municipal waste combustors (MWCs).
8. Schindler, P.J., "Municipal Waste Combustion Assessment: Combustion Control at New
Facilities," EPA-600/8-89-057 (NTIS PB90-154923), August 1989.
9. Schindler, P.J., "Municipal Waste Combustion Assessment: Combustion Control at
Existing Facilities," EPA-600/8-89-058 (NTIS PB90-154931), August 1989.
12
-------
10. Schindler, P.J. and Nelson, L.P., Municipal Waste Combustion Assessment: Technical
Basis for Good Combustion Practice, EPA-600/8-89-063 (NTIS PB90-154949), August
1989.
11. U.S. EPA, Air Pollution Standards of Performance for New Stationary Sources; Rule and
Proposed Rules, 40 CFR Parts 60, 51 and 52, December 20, 1989.
12. U.S. EPA, Standards of Performance for New Stationary Sources and Final Emission
Guidelines; Final Rules, 40 CFR Parts 51, 52, and 60, February 11, 1991.
13. Miller, H., Marklund S., and Rappe, C., "Correlation of Incineration Parameters for the
Destruction of Polychlorinated Dibenzo-p-dioxins," Chemosphere, 18,7-8 (1989): 1485-
1494.
14. Shaub, W. M. and Tsang, W., "Dioxin Formation in Incinerators," Environ. Sci. and
Tech. 17 (1983): 721-730.
15. Kilgroe, J.D. et al., "Combustion Control of Organic Emissions from Municipal Waste
Combustors," Combust. Sci. and Tech., 74 (1990): 223-244.
16. Vogg, H. and Stieglitz, L., Chemosphere, 15 (1986): 1373.
17. Hagenmaier, H. et al. "Catalytic Effects of Fly Ash from Waste Incineration Facilities on
the Formation and Decomposition of Polychlorinated Dibenzo-p-dioxins and
Polychlorinated Dibenzofurans," Environ. Sci. Technol. 21 (1987): 1080-1084.
18. Stieglitz, L. and Vogg, G.,"Formation and Decomposition of Polychlorodibenzodioxins
and -furans in Municipal Waste," Report KFK4379. Laboratorium fur Isotopentechnik,
Institut fur Heize Chemi, Kernforschungszentrum Karlsruhe. February 1988.
19. Hoffman, R.V. et al., "Mechanism of Chlorination of Aromatic Compounds Adsorbed on
the Surface of Fly Ash from Municipal Incinerators," Environ. Sci. Technol. 24 (1990):
1635-1641.
20. McGrath, T.P. et al., Results of Performance Tests for Solid Fuel Test Facility, prepared
for California South Coast Air Quality Management District, by Energy and Environmental
Research Corporation, July 1989.
21. Kilgroe, J.D., Lanier, W.S., and von Alten, T.R. Montgomery County South Incinerator
Test Project: Formation, Emission, and Control of Organic Pollutants, 2nd International
Conference on Municipal Waste Combustion, Tampa, FL, April 1991.
22. Radian Corporation, Municipal Waste Combustion Multipollutant Study - Summary
Report. North Andover RESCO, North Andover, MA. EMB Report No. 86-MIN-02a,
March 1988.
23. Anderson, C.L. et al., "Characterization Test Program Emission Test Report, Marion
County Solid Waste-to-Energy Facility, Volume I: Summary of Results," U.S.
Environmental Protection Agency, Research Triangle Park, NC (EMB 81-MIN-4)
September 1989.
24. Scheil, G. et al., Municipal Waste Combustion, Multi-Pollutant Study, Emission Test
Report, Maine Energy Recovery Company, Refuse-Derived Fuel Facility, Biddeford,
13
-------
Maine, Volume I, Summary of Results, EPA-600/8-89-064a (NTIS PB90-228834), July
1989.
25. Entrophy Environmentalists, Inc., "Emissions Test Report, Municipal Waste Combustion
Continuous Emission Monitoring Program," Wheelabrator Resource Recovery Facility,
Millbury, MA, EMB Report 88-Min-OSW, January 1989.
26. Kilgroe, J.D. and Finkelstein, A., "Combustion Characterization of RDF Incinerator
Technology: A Joint Environment Canada - United States Environmental Protection
Agency Project," presented at the International Conference on Municipal Waste
Combustion, Hollywood, FL, April 11-14, 1989.
27. Kilgroe, J.D. et al., "Control of PCDD/PCDF Emissions from Refuse-Derived Fuel
Combustors," Chemosphere, 20, 10-12 (1990): 1809-1815.
28. Brna, T.G., Kilgroe, J.D., and Finkelstein, A., The Joint EC/EPA Mid-Connecticut Test
Program: A Summary, Presented at Second International Municipal Waste Combustion
Conference, Tampa, FL, April 15-19, 1991.
29. Finkelstein, A., Environment Canada, Mid-Connecticut RDF Facility Test Program
Results, personal communication, June 1991.
30. Environment Canada, National Incinerator Testing and Evaluation Program, Two Stage
Combustion, Summary Report, EPS 3/UP/l, September 1986.
31. Environment Canada, NTTEP, Environmental Characterization of Mass Burning Incinerator
Technology , Quebec City, Summary Report, EPS 3/UP/5, June 1988.
32. Midwest Research Institute, Results of the Combustion and Emissions Research Project at
the Vicon Incinerator Facility in Pittsfield, MA. Prepared for New York State Energy
Research and Development Authority, June 1987.
33. Radian Corporation, Results from the Analysis of MSW Incinerator Testing at Peekskill,
NY, Prepared for New York Energy Research and Development Authority, DCN:88-233-
012-21, August 1988.
34. Results from the Analysis of MSW Incinerator Testing at Oswego County, New York.
Vol 1, Final Report, Prepared for New York State Energy Research and Development
Authority, January 1990.
3 5. Combustion and Emissions Testing at the Westchester County Solid Waste Incinerator,
Vol I, Final Report, Prepared for New York State Energy Research and Development
Authority, January 1989.
36. Gullett, B.K., Bruce, K.R., and Beach, L.O., "The Effect of Metal Catalysts on the
Formation of Polychlorinated Dibenzo-p-Dioxin and Polychlorinated Dibenzofuran
Precursors," Chemosphere, 20, 10/12 (1990): 1945-1952.
37. Gullett, B.K., Bruce, K.R., and Beach, L.O., "Formation of Chlorinated Organics During
Solid Waste Combustion." Waste Management & Research 8 (1990): 203-214.
14
-------
38, Bruce, K.R., Beach, L.O., and Gullett, B.K., "The Role of Gas-Phase Cl2 in the
Formation of PCDD/PCDF During Waste Combustion," Waste Management, 11 (1991):
97-102.
39. Bruce, K.R., Gullett, B.K., and Beach, L.O., "Copper-based Organic Catalysis in
Formation of PCDD/PCDF in Municipal and Hazardous Waste Incineration," Presented at
1991 Incineration Conference, Knoxville, TN, 5/13-17/91.
40. Landrum, VJ. and Barton, E.G., Municipal Waste Combustion Assessment: Fossil Fuel
Co-Firing, EPA-600/8-89-059 (NTIS PB90-159831), July 1989.
41. Landrum, V.J. and Schindler, P.J.; Municipal Waste Combustion Assessment: Waste Co-
Firing, EPA-600/8-89-060 (NTIS PB90-161001), July 1989.
42. Nelson, L.P., Municipal Waste Combustion Assessment: Fluidized Bed Combustion,
EPA-600/8-89-061 (NTIS PB90-164054), July 1989.
43. Landrum, VJ. and Barton, R.G., Municipal Waste Combustion Assessment: Medical
Waste Combustion Practices at Municipal Waste Combustion Facilities, EPA-600/8-89-062
(NTIS PB90-186990), July 1989.
44. Kilgroe, J.D., "Combustion Control of Trace Organic Air Pollutants from Municipal Waste
Combustors." Environmental Impact Assessment Review 35, Vol 9, No. 3, September
1989.
45 Nelson, L.P., Schindler, P., and Kilgroe, J.D., "Development of Good Combustion
Practices to Minimize Air Emissions from Municipal Waste Combustors." Presented at the
International Conference on Municipal Waste Combustion, Hollywood, FL, April 11-
14,1989.
46. Agrawal, S.R. and von Alten, T.R., Energy and Environmental Research Corporation,
"Good Combustion Practice for MWC Facilities: CO Emission Limit Requirement,"
(entered in EPA Docket No. A-89-08), prepared for U.S. Environmental Protection
Agency, Air and Energy Engineering Research Laboratory, by Energy and Environmental
Research Corporation, November 1990.
47. U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards,
RTP, NC, "Municipal Waste Combustion: Background Information for Promulgated
Standards and Guidelines—Summary of Public Comments and Responses," EPA-450/3-
91-004 (NTIS PB91-168534), December 1990.
48. The Clean Air Act As Amended November 1990, U.S. Government Printing Office,
Washington: 1990.
49. Agrawal, S.R. and von Alten, T.R., "Good Combustion Practice for MWC Facilities:
Maximum Steam Load Requirement," (entered in EPA Docket No. A-89-08), prepared for
U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory,
by Energy and Environmental Research Corporation, November 1990.
50. Larder, W.S. and von Alten, T.R.,"Good Combustion Practice for MWC Facilities: PM
Control Device Inlet Temperature Requirement," (entered in EPA Docket No. A-89-08),
prepared for U.S. Environmental Protection Agency, Air and Energy Engineering Research
Laboratory, by Energy and Environmental Research Corporation, November 1990.
15
-------
51. Lanier, W.S. and von Alten, T.R., "Good Combustion Practice for MWC Facilities: Start-
up and Shutdown," (entered in EPA Docket No. A-89-08), prepared for U.S.
Environmental Protection Agency, Air and Energy Engineering Research Laboratory, by
Energy and Environmental Research Corporation, November 1990.
16
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bO
2
~ti
3.
Q
en
i
Q
U
Q
U
10
8-
6 -
4 •
2-
R2=0574
10
12
14
16
UNCONTROLLED ASH / REFUSE FED (kg/Mg)
FIGURE 1. CDD/CDF VS PM CARRYOVER
QUEBEC CITY - MASS BURN INCINERATOR
u
iuu -
CD £
Ul «
IA L^
tfi n 50 •
UH
Percentage Change in CDD/CD
Increase
J 10 ^ ^
58 8 8 S c
i.l.i.i-i
2:
IA •
A .
. ' •
• PinellasCo.
# North Andover
• A Peekskill
* • Oswego
>0 240 260 280 300 32
Temperature at ESP Inlet (deg. O
FIGURE 2. CHANGE IN CDD/CDF AT INLET AND OUTLET
OF ESP WITH INLET TEMPERATURE 10
17
-------
2000-
CN
O
u
»o 1500
&•-
a
£
•o
^ woo-
^c
tu
e
o
D «,/,
U 500
n -
R2 = 0.70
O
o
0
o
0
0°
«
*
*
O Good operation
* Poor operation
200
400 600
CO(ppm)
800
1000
3. CDD/CDF ¥S CO IN FLUE GAS AT SPRAY DRYER INLET
MID-CONNHmCUT KDF COMBUSTION FAOUTY M
IUUUUU 1
g loooo i
O :
*s :
P^
| 1000 1
TJ
c3 100 1
(u ;
Q ;
u
O 10-
Q i
U :
1 •
01 -
1C
%
%*
• • m
•
f» 4
IN OUT 1
u. .. _ . ^ ... 0 » 1
B ; o H (
0 150 200 250
4^
• ^
-------
TABLE 1. MWC RULES FOR GOOD COMBUSTION PRACTICE
Parameter/MWC Technology
Requirement
Existing
CO Emissions
-Mass Burn Waterwall
-Mass Burn Refractory
-Mass Burn Rotary Waterwall
-Modular Starved Air
-Modular Excess Air
-RDF Stoker
-Bubbling Fluidized Bed
-Circulating Fluidized Bed
-Coal/ RDF Co-Fired
Limit,ppm
100
100
250
50
50
200
100
100
150
Avg Time,!!!
4
4
24
4
4
24
4
4
4
New
Limit,ppm
100
100
100
50
50
150
100
100
150
Avg Time,hr
4
4
24
4
4
24
4
4
4
Load3
PM Control Device Inlet Temperature3
Not to exceed 110% of average load demonstrated
during most recent CDD/CDF compliance tests (4-
hour avg).
Not to exceed 17°C (30°F) above average PM control
device inlet operating temperature demonstrated
during most recent CDD/CDF compliance test (4-
hour avg).
Applies to all technologies.
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AEERL-P-852
TECHNICAL REPORT DATA
I Please read Injunctions on the reverse before complc'
5. REPORT NO.
EPA/600/A-92/267
2.
3.
4. TITLE AND SUBTITLE
Development of Good Combustion Practice for
Municipal Waste Combustors
5. REPORT DATi
6. PERFORMING ORGANIZATION CODE
7, AUTHOR(S)
J.D.Kilgroe (EPA/AEERL), and W. S. Lanier and
T.R. von Alten (EERC)
B. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10, PROGRAM ELEMENT NO.
Energy and Environmental Research Corporation
3622 Lyckan Parkway, Suite 5006
Durham, North Carolina 27707
11. CONTRACT/GRANT NO.
68-03-3365
12, SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Air and Energy Engineering Research Laboratory
Research Triangle Park, North Carolina 27711
13. TYPE OF REPORT AND PERIOD COVERED
Published paper; 9/87 - 11/90
14. SPONSORING AGENCY CODE
EPA/600/13
is.SUPPLEMENTARY NOTES
project officer is James D. Kilgroe, Mail Drop 65, 919/
541-2854. 15th National ASME Waste Processing Conference, Detroit, MI, 5/17-
20/92.
paper summarizes the rationale for EPA's good combustion practice
(GCP) strategy^ NOTE: The EPA is developing new air pollution rules for all new
and existing municipal waste combustors (MWCs), rules requiring all MWCs to use
GCP. ^he goals of GCP are to maximize furnace destruction of organic pollutants,
limit the relative amount of particulate matter (PM) carried out of the combustor
with flue gases (PM carryover), and ensure that the PM control device is operated
at temperatures that do not result in the formation of excessive amounts of
chlorinated dibenzo-p-dioxins and pol-ychlorinated dibenzofurans (CDD/CDF).
EPA's strategy incorporates three continuous compliance parameters: carbon mon-
oxide (C0) emissions, furnace steam load, and PM control device inlet temperature
Experimental data are provided to show that furnace emission of organics is corre-
lated with CO concentration, the amount of PM carryover (which is related to load),
and temperature at the PM control device inlet. The relationships between the GCP
compliance parameters and other combustion parameters which are necessary in-
gredients of good combustion (uniformity of waste feed, the amount and distribution
of excess air,, combustion temperature and residence time, and mixing of combus-
tion air with thermal decomposition products) are also discussed.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Pollution
Combustion
Wastes
Organic Compounds
Particles
Carbon Monoxide
Pollution Control
Stationary Sources
Municipal Waste Com-
bustors (MWCs)
Good Combustion Prac-
tice (GCP)
13B
21B
14G
07 C
07B
. DISTRIBUTION STATEMENT
Release to Public
19, SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
20
20. SECURITY CLASS (This pagej
22. PRICE
EPA Form 2220-1 (9-73)
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