1 MEMORANDUM

TO: Jim Eddinger, U.S. Environmental Protection Agency, OAQPS

FROM: Amanda Singleton and Graham Gibson, ERG

DATE: 23 March 2010

SUBJECT: Development of Baseline Emission Factors for Boilers and Process Heaters at Commercial, Industri al, and Institutional Facilities

1.0 INTRODUCTION

T his memorandum discusses the processes used to develo p baseline emission factors for boilers and process heaters based on data reported by industry in the 2008 Questionnaire for
Boilers , Process Heaters , Incinerators and Other Combustion Units (ICR No. 2286.01, OMB
Control No. 2060

- 0616, EPA Form No. 5900

- 122) and the 2009 Test Plan for Boilers and Process Heaters (ICR No. 2286.03, OMB Control No. 2060

- 0616, EPA Form No. 5900

- 122)

. ERG developed two dat abases: 1) a comprehensive survey database containing all data reported by industry during the 2008 Combustion Survey (herein referred to as the Survey Database 1 ) and 2) a comprehensive emission database containing all the stack test results, continuous e missions monitoring (CEMS) data, and fuel analysis data reported in the 2008 Combustion Survey and the 2009 Phase II Test Plan (herein referred to as the Emission Database 2 )

. A data dictionary and description of all the fields contained in the Survey D ata base are summarized in other
memoranda 3 . The standardization of reported emission data in both the Survey and Emission
databases is also described in other memoranda 4

. The development of baseline emission factors followed a four

- step process: First, a list
of unique combustion units reported in the Survey database was compiled. Next, t he reported
fuels combusted and control device s installed were categorized. Third
, for all units reporting emission data, all available e mission data for a unique combu stion unit were averaged and2 assigned as a unit

- specific baseline emission factor. F inally, to fill data gaps at units not reporting emission data, the emission data from other units assigned to the same fuel, control device, and combustor design categorie s were average d in order to develop an average baseline emission factor for similar types of units.
Baseline emiss ion factors were developed for 23 specific pollutants based on the fuel and
control device combinations or fuel and combustor design combinati ons utilized by the combustion devices reported in the questionnaire. These emission factors will be used to determine the control devices necessary to meet emission limits and estimate potential emission
reduction for the National Emission Standards for Hazardous Air Pollutants for boilers and process heaters at Industrial, Commercial and Institutional facilities.

This memorandum is divided into the following sections:
1.0 Introduction
2.0 Grouping Data According to Fuel Type, Control Device, and Combustor Desig n 3.0 Development of Unit

- Specific Emission Factors
4.0 Development of Average Baseline Emission Factors
5.0 Baseline Averages for Area Sources
6.0 References Appendix A: Glossary Appendix B: Fuel and Control Device Groupings Appendix C: Estimated Percent Reductions fr om Control Device Groupings Appendix D: Baseline Emission Factors for Boilers and Process Heaters at Major Sources Appendix E: Baseline Emission Factors for Boilers at Area Sources

NOTE: Technical terms and acronyms used in the text, tables, and appendic es of this
memorandum are described in Appendix A

.3 2.0 GROUPING DATA ACCORD ING TO FUEL TYPE, CO NTROL DEVICE, AND
COMBUSTOR DESIGN

The first step of the baseline emission factor process involved targeting select pollutants, developing a comprehensive lis t of all combustion units reported in the questionnaire , and categorizing combustion units according to standardized fuel groups , control d evices , and combustor designs reported the questionnaire. The procedures used to characterize the qualitative data f rom the questionnaire into appropriate groups are discussed in this section

.

2.1 Pollutants

Baseline emission factors are specific to a certain t ype of pollutant

. Twenty

- three
different pollutants were targeted in this analysis , all of which are listed in Table 1

. Although
dat a were reported for more than 2 4 pollutants, baseline emission factors were only developed
for those listed in Table 1 because these pollutants represent pollutants regulated under Section 112 of the Clean Air Act (as amended in 19 90) (CAA), or represent surrogates for pollutants regulated under the CAA, or represent pollutants that EPA uses to quantify the human health benefits resulting from a rulemaking.

Table 1

– Pollutants Assigned Baseline Emission Fa ctors
Pollutant
Antimony (Sb) Arsenic (As)
Beryllium (Be) Cadmium (Cd)

Carbon Monoxide (CO) Chlorine (Cl2)

Chromium (Cr) Cobalt (Co)
Filterable Particulate Matter (total) (PM

- filter) Formaldehyde

Filterable Particulate Matter of less than 2.5 microns (PM 2.5) Hydrogen Fluoride (HF)4 Pollutant
Hydrogen Chloride (HCl) Manganese (Mn)

Lead (Pb) Nickel (Ni)
Mercury (Hg) Selenium (Se)
Oxides of Nitrogen (NOx) Total Hydrocarbons (THC)

Sulfur Dioxide (SO 2 ) Total Mass Dioxins/Furans (PCDD/PCDF)
Volatile Organic Co mpounds (VOC)

2.2 Developing a Comprehensive List of Combustion Units

Each record in the Data: Unit Design/Operation table of the Survey Database correlates to a single combustion unit. The information for this table was derived from section II.B of t he Questionnaire 5

. In addition
, small, gas

- fired boilers or process heaters were reported under
section II.A of the Questionnaire . The definition of a small, gas

- fired combustion unit is any unit firing natural gas, propane, liquefied petroleum gas (LPG) , or refinery gas with a design capacity less than 10 million British thermal units per hour (MMBtu/hr). These groups of small combustion units, each treated as a single combustion unit for the purpose of developing b aseline
emission factor s , are only pre sent in the Data: GCP and CombustionControls table of the Survey
Database

. A n inventory of all the combustion units contained in the Data: Unit Design/Operation table as well as the small, gas

- fired units in the Data: GCP and CombustionControls table. Thi s inventory was then filtered down to only combustion units classified as boilers or process heaters at major sources of hazardous air pollutant (HAP) emissions. This resulted in a total of 13,4 34 unique boilers and process heaters , with 6,391 of those be ing small, gas

- fired units

.

2. 3 Fuel Categories

T he Questionnaire provided a drop

- down list containing 134 different fuels and materials5 and it also allowed users to self

- report additional types of fuels and materials not included in the
list. These fuel s were categorized into one of the 11 fuel categories listed in Table 2 . A list mapping each fuel category in Table 2 to specific fuel types reported in the survey can be found
in Table B.1 of Appendix B. Since many boilers and process heater s fire multip le types of fuels, a fuel hierarchy was established to assign each multi

- fuel boiler and process heater to a specific fuel category. For units firing multiple fuels, f uel categories were assigned based on the percentage of the total heat input contributed by each fuel. A threshold of 25 percent was used in order to assign a fuel category based on the hierarchy listed in Table 2 . For example, if the total heat input at a unit was comprised of 80 percent coal and 20 percent natural gas, it was placed in the Coal category because the unit was combusting at least 25 percent coal on a heat input basis . In order for a combustion unit to be classified as any fuel lower in the hierarchy, each of the fuels ranked higher must all contribute less than 25 percent to the unit’s total heat input. For example, if a combustion unit’s total heat input was comprised of 20 percent coal and 80 percent natural gas, it was placed in the Natural Gas category.

Table 2

– Categorical Fuel /Material Hierarch y Rank Fuel Category

1 Coal

2 Bagasse

3 Wet Biomass

4 Dry Biomass

5 Heavy Liquids

6 Light Liquids

7 Process Gases

8 Natural Gas6 Rank Fuel Category

9 Other Non

- Process Gases (including refinery gas, LPG, propane, hydrogen)
10 Other Fuels

11 Waste

For baseline pur poses, petroleum coke was included in the Coal category. Any unspecified type of biomass was assumed to be dry biomass. The liquid fuel categories encompass both fossil

- and non

- fossil

- derived fuels in liquid form such as sludges

. Emissions
data from te sts conducted while combusting waste were not included in baseline calculations.
The definition of waste is detailed in another memorandum 7

.

2. 4 Control Device Categories

C ontrol devices reported in the Questionnaire were c ategorized according to their ability to remove certain types of pollu t ants. Since certain control devices target different types of pollutant s , the pollutant s themselv es were first categorized into groups. Table 3 shows the groupings created for these pollutants.

Table 3

– Pollutant Groupings Category Constituent Pollutants

Inorganic HAP and SO 2 Hydrogen Chloride (HCl)
Hydrogen Fluoride (HF)

Chlorine (Cl 2 )

Sulfur Dioxide (SO 2 )
Mercury (Hg) Mercury (Hg)

Particulate Matter (PM) Filterable Particulate M atter7 Category Constituent Pollutants

PM2.5

Non

- Mercury Metallic HAP Antimony (Sb)

Arsenic (As)
Beryllium (Be)

Cadmium (Cd)

Chromium (Cr)

Cobalt (Co)

Lead (Pb)
Manganese (Mn)

Nickel (Ni)

Selenium (Se)

Organic HAP and Combustion

Based Pollutants Carbon Monoxide (CO)
Formaldehyde
Oxides of Nitrogen (NOx)
Total Hydrocarbons (THC) Volatile Organic Compounds (VOC)

Total Mass Dioxins/Furans Total Mass Dioxins/Furans (PCDD/PCDF)

Control devices were reported in many separate sections in the Questionnaire. All con trol
device data reported with the emission test and CEMS data, as well as the in the Data: Control
Device table in the Survey Database
, were identified for each combustion unit

. Each of the8 control configuration s reported for a boiler or process heater w as further categorized to reflect only the control device or devices that are effective at removing any of the pollu t ants in Table 3

. Control devices that have little or no effect on any of the pollutants listed in Table 3 were classified as having no con trol equipment installed . For example, selective catalytic reduction (SCR) is not effective in reducing the concentration of any pollutants listed in Table 3 . Thus
, any combustion unit that employed SCR was c lassified as having no air pollution control d evice (APCD). Similarly, if a combustion unit reported a control configuration of an electrostatic precipitator coupled with SCR
, the “total baseline control ” was standardized to “Electrostatic Precipitator.” Further, if a unit reported more than one cont rol device that was effective at removing a particular pollutant, the most efficient control device was included in the “total baseline control.” For example
, if a un it reported a multiclone and electrostatic precipitator, the
total baseline control was st andardized to “Electrostatic Precipitator”. These standardized control configurations were classified into groups based on their effectiveness in the removal of the pollutant s listed in Table 3 . Control group s were created for Inorganic HAP and SO 2 , Metal lic HAP, Mercury, and Particulate Matter . S ince add

- on control technologies reported in the questionnaire do not achieve reductions in dioxin/furan, organic HAP, CO, or THC , no control groups were assigned to the Organic HAP group

. For each group of pollu tants, control devices were ranked according to their effectiveness and assigned to a

group. The lowest numbered group s represent the best

- performing controls for a particular set of pollutants . For example, a wet scrubber is recognized to be the most eff ective control device at removing acid gases in the Inorganic HAP and SO 2 group. Thus, a wet scrubber would be assigned to “Control Group 1” for those pollutants. A wet scrubber is also expected to remove modest amounts of particulate matter and metallic HAP, and it was assigned to “Control Group
3” for the Metallic HAP pollutant group , behind spray dryer/FF and spray dryer / ESP control configurations. A list of the standardized “total baseline control ” configurations and their groupings for the Inorganic HAP and SO 2 , Mercury, Particulate Matter, and Metallic HAP can be found in Tables B.2.A through B.2.D , respectively, of Appendix B

.

2.5 Combustor Designs

Since formation of organic HAP is influenced by the design of a combustion chamber,9 boilers and pro cess heaters firing solid fuels were classified according to combustor design. Combustor design categories depended on the fuel category the unit was assigned to. Table 4
lists the combustor design subcategories within each fuel category.

Table 4

– Combustor Designs Fuel Category Combustor Designs

Coal Fluidized Bed

Pulverized Coal
Stoker/Sloped Grate/Other

Bagasse, Wet Biomass, and Dry Biomass Dutch Oven/Suspension Burner

Fluidized Bed

Fuel Cell

Gasifier
Stoker/Slope d Grate/Other
Residual/Heavy Liquids N/A
Distillate/Light Liquids N/A

Process Gases N/A

Natural Gas N/A

Other Non

- Process Gases N/A

Other Fuels N/A

Stoker boiler designs include spreader stok ers, overfeed stokers and mass feed stokers.
These boiler s feed fuel to a grate and forced air and combustion controls coordinate the air and fuel supply to the boiler. Pulverized coal boilers pulverize the coal down to a powder and then inject the powdered fuel and air into the combustion chamber where the fuel combusts in10 suspension. Both dutch ovens and suspension burners are often designed to handle fuels with higher moisture contents (e.g., logging and timber residue, bagasse). In dutch ovens, the fuel is distributed onto grates and air flows up through the grates provides oxygen for combustion, cools the grates, and dries the fuel. Underfire air partially burns the fuel and then combustion of the volatile gases is completed in a secondary chamber . For suspension burners, fuel particles are
combusted after be ing pneumatically suspended in an airstream.
Combustion units were assigned to a combustor design based on the information reported
in the Data: Unit Design/Operation table of the Survey D atabase. If a unit did not enter combustor design information, or if the combustor design reported was reported as a type other
than those listed above it was placed in the Stoker/Sloped Grate/Other category since stoker designs represent the majority of boilers and process heaters designed to burn biomass or coal

. Some emissions data represents more than one combustion unit. In these cases, the combustor design for each individual combustion unit was reviewed. If all of the units shared the same combustor design, that common combustor design was used to characterize th e data. If the multiple combustion units represented multiple combustor designs, the data was not used for baseline calculations because it did not belong to any combustor design subcategory. Instead, its combustor design category was labeled as “Multiple Combustor Designs”.
Sometimes a combustion unit reported more than one type of combustor design, in the Survey Database a nd a hierarchy was used to classify that unit to one of the combustor design categories . For coal units, the hierarchy was pulverized coal units
, followed by fluidized beds
and then stokers. Other designs not classified as pulverized coal, stoker, or fluidized bed were included in the stoker design category. For biomass units, the hierarchy was fluidized bed
, followed by stokers (inclu ding sloped grate) , dutch ovens and suspension burners, fuel cells, and
then gasifiers . Other designs not classified as, stoker, fluidized bed, fuel cell, dutch oven, or gasifiers were included in the stoker category

.

3.0 DEVELOPMENT OF UNIT

- SPECIFIC EMI SSION FACTORS

Before a n average baseline emission factor could be developed for a certain pollutant, each combustion unit was first assigned its own unit

- specific emission factor where data were available. The process of assigning unit

- specific emission factors is discussed in this section.11 3.1 Selecting the Data Source for Unit

- Specific Data Averages

Emission was reported in several sections of the 2008 Combustion Survey and some sources reported additional emission data under the 2009 Phase II ICR tes ting. Only emission
data that could be standardized to common units of measured were used to determine unit

specific emission factors. The procedures used to standardize emission data are discussed in
another memorandum. 2 Standardized emission test, CEMS monitoring data, and fuel analysis data were averaged for each boiler reporting these data. For units reporting multiple types of
emission data, Table 5 shows the hierarchy for determining which data source was used as the
basis for the baseline emission s at the boiler or process heater.

Table 5

– Hierarchy for Determining Unit

- Specific Baseline Emission Factors Rank Condition

1 If a unit had emission test averages and CEMS data averages and the values were within the same order of magnitude
, CEMS and emi ssion test averages were averaged together

. 2 If a unit had emission test and CEMS data averages and the values were not within the same order of magnitude, only the emission test average was used.
3 If a unit had only an emission test average, that valu e was used.

4 If a unit had only CEMS data, th e average of the reported CEMS data was used.

5 If a n uncontrolled unit designed to burn liquid fuel s had no emission test or emis sion monitoring data but reported fuel analysis data for metallic HAP, mercury , or chlorine (standardized to hydrogen chloride) , the average of all the standardized fuel analysis data in the unit’s fuel category (light or heavy liquid)

w as assigned as the unit’s baseline emission factor.

6 Boilers or process heaters with no emissi on test or CEMS data, as well as liquid

fired units with no fuel analysis data were not assigned a unit

- specific emission factor and were assigned to an average baseline emission factor as discussed in Section 4.

3.2 Assigning Appropriate Fuels and Con trol Devices

Similar to how unit

- specific emission factor values came from different data sections of12 the survey, fuel and control device data were often reported in multiple sections of the survey.
Tables 6

- 7 show the hierarchies used to determine the fu el and control device, respectively, for
each unit

- specific emission factor.

Table 6

– Hierarchy for Determining Fuels for Unit

- Specific Emission Factors Rank Source

1 If emission test or CEMS data were available, the fuels reported during these tests or monitoring periods were used. Tests on multiple fuels or control configurations were assigned separate record identifiers as discussed in Section 3.1.1 2 Small, gas

- fired units (as defined in Section 2.2 above) located at refineries (NAICS code 324) were assumed to be combusting refinery gas. 3 The remaining small, gas

- fired units (as defined in Section 2.2 above) were assumed to be combusting natural gas.

4 A combination of all fuels listed as being routinely combusted for that specific combustion unit as listed in the Data: Materials Combusted table of the Survey Database. 5 The fuel associated with the design capacity of the combustion unit as listed in the Data: Unit Design/Operation table of the Survey Database.

6 A combination of all fuels listed as being combusted for that specific facility as listed in the Data: FuelAnalysis Background Information table of the Survey Database.

Table 7

– Hierarchy for Determining Control Devices for Unit

- Specific Emission Factors Rank Source

1 If emission test or CEMS data were available, the control devices reported to be installed during these tests or monitoring periods were used. Tests on multiple fuels or control configurations were assigned separate record identifiers as discussed in Section 3.1.1.

2 A combination of all current control devices reported to be installed on the combustion unit as listed in the Data: Control Device table of the Survey Database. 3 If no control device information was reported for a combustion unit, it was assumed to have no add

- on control devices.13 Rank Source

4 Since cyclones are often considered integral equipment to a boiler and not an add

- on control device, units combusting coal and/or biomass who did not report having any controls installed were assumed to have a cyclone installed for Metallic HAP and Particulate Matter control. The ‘total baseline control’ category for these units remained classified as having no HAP control, but solid fuel boilers without reported controls and with cyclone/multiclone reported control assigned to the same control group for Metallic HAP and Particulate Matter. .

After the preferred data source for fuels combusted and control devices installed were determined, the reported fuels were assigned to fuel categories described in Section 2.3 and the

repo rted control devices were assigned to control groups, as described in Section 2.4 . These categories allowed baseline emission factors to be developed for each combination of fuel and
control device

. Several times, combustion units reported different fuel and control co nfigurations
associated with emissions data than the controls and fuels reported with monitoring data. In these cases, the fuel and control device data from both sources were reviewed, and the data
deemed most representative of current opera tions were assigned to the unit . Routinely combusted fuels were reported in the Data: Materials Combusted table of the Survey Database. Current control device data were reported in the Data: Control Device table of the Survey
Database. The fuel and cont rol information reported with the testing and monitoring data were compared to these tables in order to determine the most representative fuel and control configuration. Emission and monitoring data for alternate fuel or control configurations at the
unit were not considered when calculating a unit

- specific baseline emission factor, but they were included when calculating average baseline emission factors for units with similar fuel and control device configurations.

3. 3 Emission Test and CEMS Data Avera ges Emission data averages were created using the standardized data in the Data:
EmissionsTest and Data: CEMS tables of the Emission D atabase. If a unit reported the results of
an stack test to be non

- detect, the detection limit was used as the basis for the average. Emission test data were available for all pollutants listed in Table 3 of this memorandum

. Monitoring data14 was reporting in the Survey Database on a daily average basis for CO, SO 2 , NOx, and Filterable
PM. Facil ities were unable to report em ission monitoring data as non

- detect in the Survey Database since the template to enter CEMS data required a numerical value

. Many combustion units reported emission test information for multiple fuel and control

co nfigurations

. For example, some units r eported control configurations that represent current control configurations presently installed on the unit as well as control device configurations that were installed prior to complying with the 2004 vacated NESHAP for Industrial, Commercial,
and Instit utional Boilers and Process Heaters. Other units that tend to operate on multiple fuel types may have reported multiple stack tests , for example one unit may have reported a test based on firing natural gas and another test while firing fuel oil. In order to appropriately group
emission test and monitoring data, a record identifier was created to distinguish between different combinations of fuel and control device configurations. Next, the average (mean) of all the emission test runs with the same recor d identifier was calculated. For a combustion unit with only one fuel and control device combination, the record number was assigned as “1.” For combustion units with multiple combinations of fuel and
control device co nfigurations , additional record numbe rs were assigned. For example, if a combustion unit with a wet scrubber reported two emission tests, one burning coal and the other burning oil, two record identifiers numbers were given. The coal/wet scrubber combination w as assigned a record number of “1” whereas the oil /wet scrubber combination was assigned “2.”
The maximum number of record identifiers assigned to a combustion unit was four, representing four unique combinations of fuel type and control device configurations. An average (mean) of all the monitoring data with the same record identifier was also
calculated. For most sources, this was a 30 day average, but some sources reported multiple 30

- day periods in the Survey Database. For combustion units that reported both emission test and
monit oring data with similar fuel and control configurations, the same record identifier was used
for both sets of data in order to allow the two datasets to be averaged, when deemed appropriate

. The calculated means for the emission test and monitoring data w ere compared, and if the mean of each dataset w as on the same order of magnitude, the emission test and emission monitoring data were averaged together and assigned to the unit

- specific baseline emission factor . If the emission test and emission monitoring data were not of the same order of magnitude, only the average emission test data was used to establish baseline emission for the unit. An order of15 magnitude was defined to be within a factor of 10.

3. 4 Fuel Analysis Data Averages The process of standa rdizing mercury and chlorine fuel analysis concentration s into
standardized emission factors is discussed in other memoranda 2

. Fuel analysis data from
uncontrolled l iquid fuels w ere standardized for chlorine (converted to HCl), Hg, and other metals ( Sb, A s, Be, Cd, Cr, Co, Pb, Mn, Ni, Se)

. Since these HAP are fuel

- based contaminants, and not a product of combustion, the constituents within the fuel are expected to be emitted in the exhaust gas. Since the liquid fuels are often delivered to a facility and u sed in multiple combustion units at the facility, fuel analysis data were reported in Survey Database and Emission Database at the facility level. As a result, unit

- specific emission averages could not be generated. Instead, a
list of uncontrolled combusti on unit s design ed to burn liquid fuels and report ed combusting liquid fuels as per Section 2.3 above was developed from the Survey Database

. Next, all of the fuel analysis data for liquid fuels at facilities with an uncontrolled liquid unit were identified and classified as either heavy or light liquids according to Appendix B1 of this memorandum

. Because purchased liquid fuels such as fuel oils 1

- 6 are subject to ASTM specifications and are expected to be relatively homogenous from delivery to delivery, f uel analysis averages were not calculated for a specific facility or unit. Instead, each uncontrolled liquid unit was assigned to a n average baseline emission factor that was cal c u l ated by taking the mean of the all standardized fuel analysis data for bio liquids, diesel fuel, jet fuel, kerosene, and #2 and #4 oil for units in the light liquid fuel category and the mean of all standardized fuel analysis data for black liquor, #5 and #6 oil, rectified methanol, red oil, and on

- spec used oil for units in the heavy liquid category.
For example, facilities A and B each have an uncontrolled unit co mbusting distillate liquid fuel and reported fuel analysis data for chlorine

. Both combustion units would have each been assig ned the same HCl fuel analysis average generated for light liquids. Some fuel analysis data was reported as a mixture of fuels. If a liquid fuel was reported as a mixture, the corresponding data was not used to generate an average

. Fuel analysis data for any type of sludge was not used to calc ulate fuel analysis averages.

4.0 DEVELOPMENT OF AVERAGE BASELINE EMISSION FACTORS16 For units that did not report emission test, CEMS or fuel analysis data for one of the pollutants in Table 1 , average b aseline emission factors were developed using data from other boilers and process heaters with similar controls, fuels, and combustor designs. In several cases it is possible for certain pollutants to be based on unit

- specific data, where data was reported, and
the d ata gaps not reported were fill ed with average baseline emission factors. The process of identifying data suitable for use in an average baseline emission factor and calculating the average baseline emission factors is discussed in this section.

4.1 Baseline Criteria

Baseline averages were d eveloped to represent emissions from units firing similar fuel types that have similar control devices. Any emission test or emission monitoring data reported in the Survey Database wh en combusti ng any amount of waste material was not included in
baseline average calculations. Fuel analysis data for liquid waste s , or fuel analysis data that was reported for a combination of liquid fuels and waste was not used in baseline average
calculations. The definition of waste is detailed in an other memorand um 7

. Wh ile baseline averages were calculated for the Other fuel category, they were not used since all of the units in the boiler and process heater inventory were assigned to one of the other nine fuel categories in
Table 3

.

4.2 Development of Averages

To cal culate an average baseline emission factor for each pollutant
, all unit

- specific
emission factors assigned in section 3.0 were averaged for similar groups of controls, fuel types and combustor designs. Since i norganic HAP and SO 2 , m etallic HAP , Hg , and PM, are fuel

based HAP that can be controlled with add

- on pollution control devices, the unit

- specific
emission factor s were averaged across all units with a common fuel category and control group.
F ormaldehyde, NOx, and CO , are combustion

- based pollutants a nd their emissions are
influenced by the design of combustion chamber . Further
, emissions of NOx and carbon monoxide can be affected by NOx control s such as low NOx burners, overfire

- air , or flue gas17 recirculation

. As a result, the unit

- specific emission factors were averaged across all units with a common fuel category, combustor design, and NOx control configuration . Baseline averages for
THC and PCDD/PCDF are also driven primarily by the design of the combustion chamber, and
the unit

- specific emission factors were averages across all units with a common fuel and combustor design category. Based on the data reported under Phase II, emissions of THC and PCDD/PCDF at units firing natural gas and refinery gas differed significantly depending on
whether the unit was equipped with NOx controls, and so baseline emission factors for THC and PCDD/PCDF at these gas

- fired units were established by averaging data from other gas fired
units with similar NOx control configurations.

4.3 Filling Data Gaps

After calcu lating averages emission factors for each of the pollutants in Table 1 f or the unique combinations of fuels, control devices, and combustor designs there were some pollutants that did not have any emission data available to calculate an average baseline em ission factor.
For i norganic HAP and SO 2 , me tallic HAP, Hg , and PM, control efficiencies were assigned to the control groups based on literature available on pollutant removal efficiencies of various
control devices

. A list of the pollutant

- specific perce nt reductions can be found in Appendix C

. The percents listed in Appendix C are the expected reductions a given control device could achieve compared with pollutant emissions without control devices installed. There were no data gaps for the o rganic HAP pollutants for gaseous and liquid fuels. The average baseline formaldehyde emissions from coal

- fired fluidized bed boilers were approximated using the average emission from coal

- fired stoker/sloped grate/other boilers. For THC, formaldehyde and NOx emissi ons from dutch oven/suspension burners firing wet biomass, the baseline emissions were approximated using the emissions from dutch oven/suspension burners firing dry biomass. For the one unit that was classified as a gasifier burning dry biomass, its emis sions assigned to the emissions from the dry biomass Stoker/Sloped
Grate/Other category since gasifier is an “other” type of unit. Data gaps in the Bagasse fuel category were filled using the Wet Biomass averages from the same subcategory since Bagasse
is considered to be a very wet type of biomass.18 4.4 Review of Outli er Data

After baseline emission factors were developed for each possible subcategory, the

average values were reviewed to look for uncharacteristically high or low values. Unexpectedly high or low values were flagged and the individual data points that comprised the average were investigated. An example of flagged values for a given pollutant would be if the uncontrolled baseline emission factor was lower than that of any other control grou p for that same pollutant and the same fuel category.
The unit

- specific averages were inspected for these problematic values in order to determine if there was a problem with any of the reported da ta used in the average . Several
factors led some data to b e disregarded, such as emissions monitoring data from periods of startup or malfunction, errors with the reported units of measure , misclassification of units, fuels burned, or control devices installed. Where possible, changes were made to the reported d ata in
the Emission Database and the updated values were used to recalculate baseline emission factors. If reported data was identified as an outlier, it was not used in the average baseline emission calculations, but was used for a unit’s site

- specific b aseline emission factor. In addition to reviewing the average baseline values for outliers, the full range of unit

specific emission data was also reviewed to identify any uncharacteristically high or low values that could over or underestimate the expect ed emission reduction estimates resulting from the proposed rule.

4.5 Establishing Baseline Emissions for PM2.5 and VOC

Baseline emission factors for particulate matter less than 2.5 microns (PM2.5) were estimated as a percentage of filterable PM baselines . PM2.5 is a select portion of total filterable PM based on particle size, so it is correct to assume that a portion of total filterable PM will always be PM2.5. The ratios of PM2.5 to total filterable PM were based on reported emission
test data for bot h pollutants, and were specific to fuel types and control devices. The fractions of PM2.5 ranged from 0.07 to 1 . Details on the fractions for each fuel and control device group are presented in Appendix D

- 3

. Using the fuel category and control device con figuration assigned19 to each unit, a baseline emission factor for PM2.5 was estimated by multiplying the appropriate PM2.5 fraction by the filterable PM baseline emission factor assigned to the unit. Similar to the method used to generate PM2.5 baseline e mission factors, VOC emission factors were generated as a portion of THC baseline emissions. Monitoring data reported from
the 2009 Test Plan was used to calculate an average (mean) VOC

- to

- THC ratio that could be applied to all THC baseline emission facto rs. Only data from the 2009 Test Plan was used because it was the only source of data that correlated THC and VOC data points over a multi

- day period . VOC ratios were not calculated for each subcategory because there was only data
available for six total boilers and process heaters . A VOC

- to

- THC ratio was generated for each monitoring data point that was not noted to be during a period of start

- up, shutdown, or
malfunction. A statistical quartile analysis was performed on the set of ratios in order to r emove any outl iers . The remaining ratios were then averaged in order to get a total VOC

- to

- THC ratio, which was applied to each THC baseline emission factor subcategory. It was assumed that this ratio would not fluctuate between different fuel categories or control devices. Based on monitoring data available from these six sources, THC emissions are composed of 57 % VOC.
The data used to calculate this percentage is presented in Appendix D

- 4

.

4.6 Establishing Baseline Emissions for Total Mass Dioxins/Fur ans

Baseline emission averages for total mass dioxins/furans were calculated differently than the rest of the pollutants due to the way dioxin/furan data was reported in the Emission Database

. Facilities were able to report a total mass emission value, o r total mass values for 17 individual
dioxin/furan co n geners and a group of “other co n geners”

. Table 8 lists the dioxin/furan

co n geners used to calculate total dioxin/furan emissions

.

Table 8

– Dioxin/Furan Co n geners Total Mass Dioxin/Furan Co n geners
1, 2,3,4,6,5,7,8 OCDD 1,2,3,7,8 PeCDD

1,2,3,4,6,5,7,8 OCDF 1,2,3,7,8 PeCDF
1,2,3,4,6,7,8 HpCDD 1,2,3,7,8,9 HxCDD20 1,2,3,4,6,7,8 HpCDF 1,2,3,7,8,9 HxCDF

1,2,3,4,7,8 HxCDD 2,3,4,6,7,8 HxCDF

1,2,3,4,7,8 HxCDF 2,3,4,7,8 PeCDF
1,2,3,4,7,8,9 HpCDF 2,3,7,8

- TCDD

1,2,3,6,7,8 HxCDD 2,3,7,8

- TCDF

1,2,3,6,7,8 HxCDF Other Co n geners

Only Phase II data was used to generate dioxin/furan averages because Phase I data was
not received for individual co n geners and data reported in Phase I were not reported on a total

mas s basis. For each emission test, a total mass dioxin/furan value was generated for each run. If the facility reported a total dioxin/furan value or detection limit , it was used. If no numerical value or detection limit was provided
, the sum of the value s of the co n geners listed in Table 8
was used to calculate a total mass of dioxin/furan emissions . The total dioxin/furan value for each run was averaged to get a test average specific to a combustion unit. These averages were
used as unit

- specific emiss ion factors for their respective combustion units.
To calculate average baseline emission factors, these test averages were averaged ac r oss units in the same fuel and combustor design. Baseline emission factors were not generated for TEQ dioxins/furans. Baseline emission factors for total mass dioxins/furans for major and area sources are presented in Appendices D

- 1 and E, respectively.

5.0 BASELINE AVERAGES FOR AREA SOURCES

Although a small number of area source facilities with boilers and process he aters reported emission data in the Survey Database, there was not sufficient data available to create a separate set of b aseline emission averages for area source boilers. Instead, the average baseline emission factors calculated for major source boilers and process heaters were used to establish
the baseline emissions from area source model units used to estimate the impacts of the proposed rulemaking

. Based on data available in the Survey Database, Title V permits for area source boilers,21 and data from t he National Forest Service Fuels for Schools program, most boilers at area
sources are uncontrolled 1
, 8

. Further, the distribution of control devices on solid fuel area source
boilers units in Pennsylvania and Wisconsin indicate that 8 percent of wood/biom ass boilers greater than 10 MM Btu/hr in these two states do not have any listed control, and the other 92 percent have an mechanical collector (e.g., multiclone, cyclone) control device installed. Further, 53 percent of coal boilers in Pennsylvania do not have any listed control. The remaining boilers firing solid fuels at area sources have an mechanical collector control device. Using th is information on control devices, we assigned average baseline emission factors for the area source
model units accordin g to Table 9 below.

Table 9

– Baseline Emission Factor Assignments to Area Source Boilers Area Source Model

Unit Pollutant Type Corresponding Major Source Baseline Emission Factor Category

Biomass Fuel

- based pollutants A verage of wet and d ry b iomass f or uncontrolled/cyclone controlled

Combustion

- based pollutants Average of wet and dry biomass stokers with NOx control

Coal Fuel

- based pollutants Uncontrolled/cyclone controlled coal

Combustion

- based pollutants Coal stokers with NOx control

Residual

Liquid Fuel

- and

- combustion

- based pollutants Uncontrolled heavy liquid

Distillate

Liquid Fuel

- and

- combustion

- based pollutants Uncontrolled light liquid

Fuel

- based pollutants include: PM, Hg, metallic HAP, inorganic HAP, and SO 2 Combustion

- based pollutants include: THC, CO, PCDD/PCDF, and formaldehyde

6 .0 REFERENCES [UNDER DEVELOPMENT]
1. Survey Database version X. Date.
2. Emission Database Version X. Date.
3. Memorandum from Susan McClutchey and Amanda Singleton, ERG, to Jim Eddinger,22 EPA, Data Dictionary for Ma jor Source Boiler and Process Heater Database . April,
2 0 10

. 4. Memorandum from Graham Gibson and Amanda Singleton, ERG, to Jim Eddinger, EPA, Standardization of Reported Data from the Questionnaire for Boilers, Process Heaters,
Incinerators and Other Combust ion Units . April XX , 20 10

. 5. Answer Key
6. Survey Overview Document
7. Waste definition memo ??
8. Memorandum from Jim Eddinger to Docket MACT Floor Analysis for the Industrial, Commercial, and Institutional Area Source Boilers Area Source MACT Floor Database. April 2010.23 APPENDIX A

GLOSSARY24 Table A. 1: Glossary

Term Description
APCD Air pollution control device. An add

- on exhaust stack technology that reduces the concentrations of HAP in exhaust gas. Btu British thermal unit. A unit of measurement fo r energy.

CO Carbon m onoxide. A common pollutant produced due to th e incomplete combustion of fuel. HAP Hazardous air pollutant. See Table 1 for a list of all HAP associated with this rulemaking effort

. Hg Mercury. This abbreviation is used to refer to both the mercury pollutant itself as well as the pollutant group created for it. Inorganic A pollutant category that is comprised of the pollutants hydrogen chloride (HCl), hydrogen fluoride (HF), and chlorine (Cl2)

. LPG Liquefied petroleum gas. A h ydrocarbon fuel derived from petroleum, stored under pressure in the liquid phase. Metallic HAP A pollutant category that is comprised of the pollutants antimony (Sb), arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), cobalt (Co), lead (Pb), mang anese (Mn), nickel (Ni)
, and selenium (Se). MMBtu/hr One million British thermal units per hour. A unit of measurement for thermal energy. NOx Nitrogen oxides. A grouping of binary compounds composed of the elements nitrogen and oxygen, including nitri c oxide (NO), nitrogen dioxide (NO 2 ), nitrous oxide (N 2 O), dinitrogen trioxide (N 2 O 3 ), dinitrogen tetroxide (N 2 O 4 ), and dinitrogen pentoxide (N 2 O 5 ). Organic An organic compound is characterized as any compound containing carbon, not including carbonates, carbon oxides, cyanides, and allotropes of carbon. For this analysis, organic refers to a pollutant category that is comprised of the pollutants formaldehyde , volatile organic compounds, and total hydrocarbons (THC). PCDD/PCDF The total mass of p olychlor inated dibenzodioxins/polychlorinated dibenzofurans. The sum of reported masses for 18 co n geners including : 1,2,3,4,6,5,7,8 OCDD ; 1,2,3,4,6,5,7,8 OCDF ; 1,2,3,4,6,7,8 HpCDD ; 1,2,3,4,6,7,8 HpCDF ; 1,2,3,4,6,7,8,9 OCDD ; 1,2,3,4,7,8 HxCDD ; 1,2,3,4,7,8 HxCDF ; 1 ,2,3,4,7,8,9 HpCDF ; 1,2,3,6,7,8 HxCDD ; 1,2,3,6,7,8 HxCDF ; 1,2,3,7,8 PeCDD ; 1,2,3,7,8 PeCDF ; 1,2,3,7,8,9 HxCDD ; 1,2,3,7,8,9 HxCDF ; 2,3,4,6,7,8 HxCDF ; 2,3,4,7,8 PeCDF ; 2,3,7,8

- TCDD ; and 2,3,7,8

- TCDF

. PM Filterable p articulate matter (all sizes)

.
PM2.5 A portion of total filterable particulate matter consisting of particles less than or equal to 2.5 μm in diameter.25 Term Description
SO 2 Sulfur dioxide. A common pollutant produced from the combustion of fuels with high sulfur content. TEQ An alternative method for quanti fying the toxicity of dioxin/furan

co n geners relative to the co n gener 2,3,7,8

- TCDD. TEQ values used in this analysis are based on the 2005 World Health Organization toxic equivalency factors. THC Total hydrocarbons. Refers to the total sum of hydrocarbon

c ompounds emitted during an emission test, standardized using propane as the reference compound. VOC Volatile organic compound. Any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammoni um carbonate, which participates in atmospheric photochemical reactions.26 APPENDIX B
Fuel and Control Device Groupings27 Table B. 1: Fuel Category Constituent s

Rank Fuel Category Inclusive Fuels

1 Coal Anthracite Coal Bituminous Coal Petroleum Coke Sub

- bituminous Coal 2 Bagasse Bagasse

3 Wet Biomass Wood: Bark Wood: Unadulterated Timber

4 Dry Biomass Hog Fuel Plant

- based Agricultural Residue Sanderdust Unspecified Biomass 1 Wood: Lumber

5 Residual/Heavy Liquids Alcohol: Ethanol Alternative Li quid Fuel Black Liquor Deinking Residuals Hexane Industrial Sludge Mixed liquid residues No. 5 Fuel oil No. 6 Residual oil Other Petroleum

- based Oils Process coproduct liquid Rectified methanol Red oil (steam stripper steam condensate, incl terpenes, terpe noids, methanol, TRS) Tall oil, tall oil derivatives Turpentine Used Petroleum

- based Oils (unknown spec) Used Petroleum

- based Oils (on

- spec)

6 Distillate/Light Liquids Animal Fat/Oils/Tallow Bio liquids Diesel fuel Jet Fuel JP

- 8 Aviation Fuel Kerosene No. 2 Distillate No. 4 Fuel oil Vegetable Oil yellow grease (used cooking oil)28 Rank Fuel Category Inclusive Fuels

7 Process Gases Acid Gas Biogas Blast Furnace Gas CO gas Coke Oven Gas Ethane Isobutane Landfill Gas Methane Noncondensable Gas (includes stripper offgas) Petrochemical process ga s Process coproduct gas Process Gas Pulp mill gas 8 Natural Gas Natural Gas

9 Other Non

- Process Gases Hydrogen LPG Pilot Gas Propane Refinery gas

10 Other Fuels Knots and Knotter Rejects Nitrile pitch residue Paper and Paper Residues Paper Pellets Proce ss coproduct solid Reinjection char Stripper condensate Tire Derived Fuel (TDF) with metal s removed Wax29 Rank Fuel Category Inclusive Fuels

11 Waste 1,4

- butanediol Boiler Cleaning agents Cardboard Cellulose fuel (balcones cubes) Coal Refuse Construction/Demolition Derived Material Contraban d Envirofuel pellets/cubes Filters Fuel cubes (paper diaper clippings/refuse) Municipal Sludge Oily Paper Residues Oily Rags Paint Rags/Residues Plastics Refuse Refuse Derived Fuel (RDF) Resin Solid Residues Screen Rejects Spent Alcohol Tar Tire Derived Fu el (TDF) without metals removed Tires (whole) Toluene Used Petroleum

- based Oils (off

- spec) Used Solvents Waste Derived Liquid Fuel Wood: Treated

1 Unspecified biomass was reported in the questionnaire as “ Biomass” and was assumed to be dry.30 Table B

. 2 .A : Inorganic and SO 2 Control Groupings

Control Group Control Device

1 Spray Dryer Wet Scrubber Wet Scrubber

2 Dry Scrubber Dry S c rubber (Lime Injection) Scrubber (unknown)

3 Dry Sorbent Injection Duct Sorbent Injection Furnace Sorbent Injection Wet Lime Injection Wet Sorbent Injection
4 Venturi Scrubber

5 Activated Carbon Adsorption or Injection Cyclone or Multiclone Dry Electrostatic Granular Filter Electrified Filter Bed (EFB) Electrostatic Precipitator Fabric Filter Mist Eliminator No HAP APCD Contr ol31 Table B.2.B: Mercury ( Hg ) Control Groupings

Control Group Control Device

1 Activated Carbon Adsorption or Injection

2 Fabric Filter/Dry Srubber (Lime Injection)/SNCR Fabric Filter/Wet Lime Injection Fabric Filter / Dry Scrubber Fabric Filter / Dry So rbent Injection Fabric Filter / Duct Sorbent Injection Fabric Filter / Furnace Sorbent Injection Fabric Filter/Spray Dryer Fabric Filter / Wet Scrubber
3 Fabric Filter

4 Wet Scrubber

5 Venturi Scrubber

6 Cyclone or Multiclone Dry Electrostatic Granular Filte r Dry Scrubber Dry Sorbent Injection Duct Sorbent Injection Electrified Filter Bed (EFB) Electrostatic Precipitator Mist Eliminator No HAP APCD Control Scrubber (unknown) Spray Dryer32 Table B.2.C: Particulate Matter ( PM ) Control Groupings

Control Group Control Device

1 Fabric Filter

2 Electrified Filter Bed (EFB) Electrostatic Precipitator
3 Venturi Scrubber

4 Wet Scrubber

5 Cyclone or Multiclone Dry Electrostatic Granular Filter

6 Activated Carbon Adsorption or Injection Dry Scrubber Dry Sorbent Injection Duct Sorbent Injection Mist Eliminator No HAP APCD Control Scrubber (unknown) Spray Dryer33 Table B.2.D: Metallic HAP Control Groupings

Control Group Control Device

1 Fabric Filter

2 Electrified Filter Bed (EFB) Electrostatic Precipitator
3 Venturi Scrubber

4 Wet Scrubber

5 Cyclone or Multiclone Dry Electrostatic Granular Filter

6 Activated Carbon Adsorption or Injection Dry Scrubber Dry Sorbent Injection Duct Sorbent Injection Mist Eliminator No HAP APCD Control Scrubber (unknown) Spray Dryer34 APPENDIX C

PERCENT REDUCTIONS
(See Excel spreadsheet s )35 APPENDIX D

MAJOR SOURCE BASELINE EMISSION FACTORS
(See Excel spreadsheet)36 APPENDIX E

AREA SOURCE BASELINE EMISSION FACTORS
(See Excel spreadsheet)