REVIEW OF NOx EMISSION FACTORS
FOR STATIONARY COMBUSTION
SOURCES AND AP-42 UPDATE
R. J. Milligan, W. C. Sailor. J. Wasilewski and W. C. Kuby
Acurex Corporation
Energy & Environmental Division
485 Clyde Avenue
Mountain View, California 94042
June 1979
ACUREX FINAL REPORT 78-306
Prepared for
Task Officer: Thomas Lahre
Office of Air Quality Planning and Standards
Environmental Protection Agency
Research Triangle Park
North Carolina 27711
Contract No. 68-02-2611
Task 34
Contract No. 68-01-4142
Task 23
-------
REVIEW OF NOx EMISSION FACTORS
FOR STATIONARY COMBUSTION
SOURCES AND AP-42 UPDATE
R. J. Milligan, W. C. Sailor, J. Wasilewski and W. C. Kuby
Acurex Corporation
Energy & Environmental Division
485 Clyde Avenue
Mountain View, California 94042
June 1979
ACUREX FINAL REPORT 78-306
Prepared for
Task Officer: Thomas Lahre
Office of Air Quality Planning and Standards
Environmental Protection Agency
Research Triangle Park
North Carolina 27711
Contract No. 68-02-2611
Task 34
Contract No. 68-01-4142
Task 23
-------
TABLE OF CONTENTS
Section Page
1 INTRODUCTION '. 1
2 UTILITY BOILERS 4
2.1 NOX Emission Factors for Utility Boilers 4
2.2 Histograms of NOX Emissions for Utility Boilers ... 8
2.3 Effect of Controls on NOX Emissions
for Utility Boilers 8
2.4 Nitric Oxide as Percent Constituent of
Total NOX Emissions 13
3 INDUSTRIAL BOILERS 20
3.1 NOX Emission Factors for Large Industrial Boilers . . 20
3.2 Histograms of NOX Emissions for Industrial Boilers. . 23
3.3 Nitric Oxide as Percent Constituent of
Total NOX Emissions 23
3.4 Effect of Controls on NOX Emissions for
Industrial Boilers 28
3.5 Other Data 28
4 COMMERCIAL AND RESIDENTIAL UNITS 32
32
35
38
and Residential Units . . . . 38
4.5 Nitric Oxide as Percent Constituent of Total
NOX Emissions 38
STATIONARY RECIPROCATING ENGINES 42
5.1 NOX Emission Factors for Compression
Ignition Engines 42
5.2 NOX Emission Factors for Spark Ignition Engines ... 44
5.3 Histograms of NOX Emissions for
Reciprocating Engines 46
5.4 Nitric Oxide as Percent Constituent of Total
NOX Emissions 46
GAS TURBINES 54
6.1 NOX Emission Factors for Various Types and Sizes
of Gas Turbine Engines 54
m
4.
4.
4.
4.
1
2
3
4
NOX
NOX
and
NOX
His1
Emission
Emission
Boi 1 ers
Emission
:ograms of
Factors
Factors
Factors
NOX Emi
for
for
for
Commercial Sized Boilers . .
Residential Furnaces
Pilot Lights
ssions for Commercial
-------
TABLE OF CONTENTS (Concluded)
Section Page
6.2 Histograms of NOX Emissions for Gas
Turbine Engines 54
6.3 State-of-the-Art Control Techniques for NOX
Emissions Water Injection 58
6.4 Nitric Oxide as Percent Constituent of
Total NOX Emissions 58
iv
-------
LIST OF ILLUSTRATIONS
Figure Page
2-1 Population Histograms of NOX Emission Factors for
Horizontally Opposed Utility Boilers 9
2-2 Population Histograms of NOX Emission Factors
for Single Wall Utility Boilers 10
2-3 Population Histograms of NOX Emission Factors
for Cyclone Utility Boilers 11
2-4 Population Histograms of NOX Emission Factors
for Bituminous Coal-Fired Tangential Utility Boilers ... 12
3-1 Population Histograms of NOX Emission Factors
for Industrial Boilers 24
4-1 Population Histograms of NOX Emission Factors
for Natural Gas-Fired Commercial Boilers, Residential
Units, and Pilot Lights 39
5-1 Population Histograms of NOX Emission Factors
for Compression Ignition Engines Firing Diesel Fuel ... 47
5-2 Population Histograms of NOX Emission Factors
for Compression Ignition Engines Firing Dual Fuels .... 49
5-3 Population Histograms of NOX Emission Factors
for Stationary Reciprocating, Natural Gas Firing
SI Engines 50
5-4 Population Histograms of NOX Emission Factors
for Stationary Reciprocating Gasoline Fired
Spark Ignition Engines 51
6-1 Population Histograms of NOX Emission Factors
for Gas Turbine Engines 56
6-2 Effectiveness of Water/Steam Injection in Reducing
NOX Emissions 59
6-3 NO and N02 Concentrations at the Base of No. 3 Stack
for Various Turbine Loads, i.e., Turbine Inlet Temperature
(Reference 6-7) 60
6-4 NO and NOX Concentrations of a Small Turbine at Various
Loads Firing No. 2 Oil 61
-------
LIST OF TABLES
Table Page
1-1 Conversion Factors 3
2-1 NOX Emission Factors Survey of Utility Boilers
(English Units) 5
2-2 NOX Emission Factors Survey of Utility Boilers
(SI Units) 6
2-3 Average Percent Reduction of NOX Emission Factors
by State-of-the-Art Control Techiques for Utility Boilers
(English Units) 14
2-4 Nitric Oxide as a Constituent of Total NOX Emissions
of Utility Boilers 16
3-1 NOX Emission Factors Survey of Industrial Boilers
(10 to 100 x 106 Btu/hr) (English Units) 21
3-2 NOX Emission Factors Survey of Industrial Boilers
(2.9 to 29 MW) (SI Units) 22
3-3 Nitric Oxide as a Constituent of Total NOX Emissions
of Industrial Boilers 27
3-4 Comparison of Data from Ferrari et al. with Calculated
Averages for Same Boiler Type and Size 29
4-1 NOX Emission Factors Survey of Commercial Stationary
Steam and Hot Water Generating Units
(0.5 to 10 x 106 Btu/hr) (English Units) 33
4-2 NOX Emission Factors Survey of Commercial Stationary
Steam and Hot Water Generating Units
(0.5 to 10 x 106 Btu/hr) (English Units) 34
4-3 NOX Emission Factors Survey of Residential Steam
and Hot Water Generating Units (<500,000 Btu/hr)
(English Units) 36
4-4 NOX Emission Factors Survey of Residential Steam
and Hot Water Generating Units (<0.15 MW) (SI Units) ... 37
4-5 Nitric Oxide as a Constituent of Total NOX Emissions
of Commercial and Residential Boilers and Heating Units
and Pilot Lights 40
-------
LIST OF TABLES (Concluded)
Table Page
5-1 Baseline NOX Emission Factors Survey of Reciprocating
Compression Ignition (CI) Engines 43
5-2 Heat Rates for Compression Ignition Engines 44
5-3 NOX Emission Factors Survey of Reciprocating
Spark Ignition (SI) Engines 45
5-4 Nitric Oxide as a Constituent of Total NOX Emissions
of Reciprocating Engines 52
6-1 NOX Emission Factors Survey of Simple and Regenerative
Cycle Gas Turbines 55
-------
SECTION 1
INTRODUCTION
In order for EPA, states, and local agenices to compile reliable
emission inventories of nitrogen oxides, it is important to have accurate
and precise NO emission factors. The two major source categories
A
responsible for the bulk of all manmade NO emissions are mobile sources
A
and stationary source combustion. The Monitoring and Data Analysis
Division (MDAD) of The Office of Air Quality Planning and Standards is
responsible for determining the NO emission factors for the latter
s\
area. Hence, it is periodically necessary that MDAD critically review
the existing emission factors for the major stationary sources of NO
X
and update those factors for which newer and more comprehensive data exist.
To assist MDAD in this task, The Energy and Environmental Division
of Acurex has compiled and reviewed the NO source test data that have
X
been generated over the last several years on the major stationary
combustion sources. This compilation includes external combustion of
coals, oils and gas in boilers as well as internal combustion in
reciprocating and turbine engines.
Stationary external combustion units are covered in the next three
sections of this report. For the purposes of this report, they are broken
into four categories:
t Utility boilers >29 MW (>100 x 106 Btu/hr) input
Industrial boilers 2.9 to 29 MW (10 to 100 x 106 Btu/hr)
input
Commercial boilers 150 kW to 2.9 MW (5 x 105 to 10 x
106 Btu/yr) input
Residential furnaces and boilers -- <150 kw (<5 x 10 Btu/yr)
input
-------
Within each size category, the boilers are further classified according to
design and fuel. Section 2 is devoted to utility boilers alone.
Section 3 covers industrial boilers and Section 4, commercial and
residential units. In support of the NO emission factor tables, each
/\
section also contains population-NO emission histograms, percentage NO
^
in NO and, for utility boilers, a section on state-of-the-art control
/\
techniques and their effectiveness.
The last two sections cover stationary reciprocating engines and
turbines, respectively. The breakdown within each section is based on
size, number of strokes per combustion cycle and fuel for reciprocating
engines and size, type of cycle and fuel for turbines.
In assessing the data reviewed in this study, it was mandatory that
the following information, in addition to that needed to calculate the
NO emission factors, be known:
J\
The type of boiler or engine -- e.g., tangential, four stroke
t Boiler operating condition: "baseline"/state-of-the-art NO
/\
control techniques -- This was particularly important for
utility sized boilers and turbines; all other sources had no
NO control technique applied unless they were specifically
^
operated under a control evaluation program.
This report is concerned with emissions at the "baseline," or
as-found condition. Thus, baseline emissions are those measured generally
in the absence of any NO control techniques. For utility and
A
industrial boilers, baseline measurements were included if they were made
at 60 to 110 percent load. All data reported without the type of boiler
delineated were rejected; data reported on utility boilers, turbines, etc.
with NO control techniques specified e.g., BOOS, FGR, water injection,
A
etc. were included in the section on control effectiveness.
Table 1-1 includes thermal equivalents for fuels discussed in this
report. Since the emission factor tables are expressed both in terms of
Ib/fuel unit and ng/J, these factors were used for conversions when the
data was reported in only one set of units.
-------
TABLE 1-1. CONVERSION FACTORS
To Obtain
From
Multiply By
ng/J
ng/J NOX (as N02)
ng/J NOX (as N02)
ng/J NOX (as N02)
NOX ppm @ 3% 02 dry
lb/106 Btu
NOX ppm @ 3% 02 dry
NOX ppm @ 3% 02 dry
NOX ppm @ 3% 02 dry
NOX ppm dry
430
0.510 (natural gas)*
0.561 (oil)*
0.611 (coal)*
/ 17.9
\20.9 - % 02 dry
Thermal Equivalents*
Fuel
Bituminous coal
Lignite coal
Residual oil
Distillate oil
Natural gas
Heating Value (Gross)
10,000 - 14,000 Btu/lb*
(used 12,000 Btu/lb)
8,000 Btu/lb*
150,000 Btu/gal*
140,500 Btu/gal*
1,050 Btu/ft3
*These factors used only when data were otherwise insufficient.
Sources:
Maloney, K. L., et al., "systems Evaluation of the Use of Low-Sulfur Western
Coal in Existing Small and Intermediate-Sized Boilers," KVB Inc.,
EPA-600/7-78-153a, July 1978.
U.S. Environmental Protection Agency, "Compilation of Air Pollutant Emission
Factors," Third Edition, AP-42, August 1977.
-------
SECTION 2
UTILITY BOILERS
For the purposes of this study, utility boilers are defined as
field-erected watertube boilers with a heat input greater than 29 MW
(100 x 10 Btu/hr) used for generation of electricity. This category
includes the vast majority of field-erected boilers used for utility or
industrial electric power generation via steam production. The major
fuels fired are coal, oil, and natural gas. Within this definition, the
utility boiler population is divided into nine major boiler types and
further subdivided into seven fuel categories. Firing of subbituminous
coal is included in the bituminous category.
2.1 NOX EMISSION FACTORS FOR UTILITY BOILERS
Tables 2-1 and 2-2 contain the NO emission factors for utility
/\
boilers.* The first table is in English units and the emission factors
are based on the amount of fuel consumed. The second table is in SI units
and the emission factors are given as weight per energy unit released
lng/J).
A considerable body of data were collected for horizontally opposea
units firing bituminous coal, oil and natural gas. These data were
abstracted from several different sources (References 2-1, 2-2, 2-3, 2-4,
2-5, 2-6 and 2-7). Major differences between the new averages and the
existing AP-42 values occur in the oil- and the bituminous coal-fired
units. In the former, the NO average emission factor was 35 percent
A
lower and in the latter 50 percent higher. Because of the number of data
*The factors reported in the tables as well as the text are in terms of
NOX emissions as N02 except as noted.
-------
TABLE 2-1. N0v EMISSION FACTORS SURVEY OF UTILITY BOILERS (ENGLISH UNITS)
A
Type
Boiler
Tangential
Horizontally
Opposed
Single Wall
Vertical1"
Cyc 1 one
Wet
Bottom'
Spreader
Stoker
Overfeed
Stoker
Baseline NOX Emissions as a Function of Fuel3
Coal {lb/ton burned)
Anthracite
18
Bituminous
18b
14C (27<1)
-22X6
18
27 (8)
+50X
18
20 (11)
+ux
18
55
36 (7)
-35X
30
48 (2)
+60X
15
15 (8)
OX
5.4 (2)
Lignite
8
7 (2)
-12t
14
14
13 (1)
-7X
14
17
12 (3)
-29X
14
Oil (lb/103 Gal oil burned)
Residual
50
42 (2)
-16X
105
68 (9)
-35X
105
65 (36)
-38X
105
105
87 (4)
-17X
Distillate
28 (3)
Gas (lb/106 SCF gas)
Natural
300
200 (3)
-33X
700
570 (10)
-19X
700
340 (39)
-51X
700
700
660 (2)
-6X
Process
790 (8)
aNOx values reported in terms of NO^
b01d AP-42 value
GRecommended replacement number based on new or revised data base
Number of boilers tested
ePercent change in emissions factor
Includes one vertical and one horizontally-opposed unit
EE-T-118
-------
TABLE 2-2. NOX EMISSION FACTORS SURVEY OF UTILITY BOILERS (SI UNITS)
Type
3oiler
Tangential
Horizontally
Opposed
Single Wall
Vertical6
Cyc 1 one
wet
3ottomr
Soreader
Stoker
Overfeed
Stoker
Baseline NOX Emissions (ng/J) as a Function of Fuel4
Coal
Anthracite
310
Bituminous
320b
250"= (27
-------
points and the variety of sources, the new numbers appear to be more
justifiable than the old.
Data were also obtained for tangential units firing bituminous coal
(References 2-8, 2-1, 2-2, 2-9, 2-10, 2-11, 2-12, 2-13, and 2-14). The
NO emission factor obtained from averaging these baseline test numbers
was 22 percent less than the existing AP-42 value.
A considerable body of data were also obtained for single wall
units firing bituminous coal (References 2-8, 2-2, 2-6, 2-11 through 2-17,
2-18, 2-19, 2-20, and 2-13], oil (References 2-1, 2-2 and 2-15), natural
gas (References 2-1, 2-3, 2-4, 2-5 and 2-15) and process gas (Reference
2-16). All NO emission factors were less than those given in AP-42
A
except for bituminous coal which showed a slight increase. The decreases
for the oil-fired units (38 percent) and the gas-fired units (51 percent)
give values consistent with expected results when these units are compared
with horizontally opposed units and single wall, large industrial boilers
burning the same fuels. Consistent with the other average values obtained
for single wall and horizontally opposed boilers, it is recommended that
the average value for lignite-fired, single wall boilers be reduced from
14 Ib/ton (380 ng/J) to 13 Ib/ton (350 ng/J). The eight process gas-fired
utility boilers show an average NO emission factor of 790 lb/10 scf
A
(330 ng/J).
All of the cyclone boiler data came from a recent compilation of
previous tests (Reference 2-21). These data show less NO emission than
s\
the initial AP-42 numbers in all fuel categories. In particular, NO
A
emissions for bituminous coal-fired cyclone boilers were 34 percent less
than the initial AP-42 value. The new data are probably more accurate as
they are based on the average of seven different cyclone boilers. Some
cyclone boilers may have been better classified as large industrial units
but were included in the utility section to provide a better data base.
No new data were obtained for vertical units and only two new data
points were obtained for wet bottom units. Both of these were in the
bituminous coal category (References 2-8 and 2-1). These data suggest
that wet bottom, coal-fired boilers should have their NO emission
A
factors increased by some 60 percent. In comparison to cyclone units, the
original wet bottom boiler NO emission data seem unusually low; the new
/\
-------
data, especially in light of the recent cyclone boiler data, would seem
more reasonable for such units.
The remaining category for which new information is now available
is for spreader stoker units firing bituminous coal. New data on six
units are included (References 2-15, 2-16, 2-22, 2-23, 2-24, and 2-25).
The average NO emission value, 15 Ib/ton (270 ng/J) is a good
representative value for these units, agreeing well with the industrial
boiler NO emission factor for the same category.
/\
Although wet bottom boilers are not mutually exclusive from the
other categories, in this report they are treated separately because of
their very high NO emission rates.
2.2 HISTOGRAMS OF N0y EMISSIONS FOR UTILITY BOILERS
^\
Figures 2-1, 2-2, 2-3 and 2-4 are bar graphs of baseline NO
J\
emission factors versus number of units tested within each boiler
type/fuel category. Figure 2-1 covers bituminous coal-, oil- and
gas-fired horizontally opposed units; Figure 2-2 covers bituminous coal-,
oil- and gas-fired single wall units. Figure 2-3 covers bituminous coal-
and oil-fired cyclone units and Figure 2-4 covers bituminous coal-fired
tangential units. Since there were only two data points for natural
gas-fired cyclone units, no histogram was constructed. With few
exceptions, the data fall quite close together considering the numbers of
variables involved. Two boilers, one a gas-fired, single wall unit and
the other an oil-fired, single wall unit, were too far from the average
based on Chauvenet's criterion and, were excluded from the data presented
in Tables 2-1 and 2-2.
The variation within each boiler and fuel category may be due to
load (not all baselines were run at 80 percent load), air preheat, burner
type, furnace dimensions, differences in fuel nitrogen, amount of excess
air, errors in measurement, to name a few. Because of the number of
variables, the data are presented to only two significant figures.
2.3 EFFECT OF CONTROLS ON NO EMISSIONS FOR UTILITY BOILERS
There are several NO control techniques currently in use with
/\
utility boilers. These include:
Low Excess Air (LEA) -- The excess amount of combustion air
supplied is reduced
-------
0
Avt'rauo
. WMM 1 iW/l m
lAn 1 J V 1 1 1 1 1
IOU 200 300 400 500 600 700 800
\ ^\ m
900 1150
*.
(80)
NO.
(160) (240)
fdo.ors. In/ 10° scf (no/,))
a. Natural Gas-Fired Horizontally Opposed Boilei
Average
70
90
(MO)
(200)
(260)
N0x emission factors, lb/10 qal (ng/J)
b. Residual Oil-Fired Horizontally Opposed Boilers
Average
~r
(260)
emission factor-. In/ton (ny/,1)
(440)
(620)
(320)
(480)
m m m \m
10
Ib
m m
20 25 30 35
m
40 4!i
(800)
i. Biliniiinoiis Coal-: in."! llurizontal ly Opposed Boilers
Figure 2-1. Population histograms of NOX emission factors for horizontally opposed
utility boilers.
-------
12 _
11 _
10
9 -
8 _
7 _
6 -
5 -
4 _
1 _
11 -n
10
5 MILJ
fi
-.
5
4 _
2 -
5 -,
4 _
3 -
2 -
1 -
_ A'
f/i '
mm
Wh
w, u*
M M.
22
W&
LL a*
££
'ft jd/
. W/W/A
erage
m
///
72
E
u.
77,
%
// i
/// -__t , ,
Y/. m w.
V
t
wm . n
v r T i i i iv! i
200 300 400 500 600 700 800 1200 1300
A A
^ 1 i i V i
(80) (180) (280) <£30;
N0x emission factors lb/10 scf (ng/J)
a. Natural Gas-Fired Single Wall Boilers
Ayorxno //,
n
%
Tfr
'//
"77, 7?/
WM> ' w.
Tl/tf/JT/jj.
wttM/,
WutfLMt.
m Tmv/y/,
'//<
'//<
//,
'//
7,
'//<
}),
Y/
W<
25 50 7
A
"V |
'. 70 :
N0x emission factor
b. Residual Oil -Fired
Avei
VA U^ M Wk
10 15 2
A
(22
s,
Sin
ag<
J '{
% \
yg r-, *
W/. R
1 1
5 100 125
f
>0) !370'
lb/103 gal (ng/J)
gle Wall Boilers
* r
-
mm m
i i i
0 25 30 35
v 1 1 1
(270) (450'.
c.
N0x (Mission factors, Ib/ton (ng/J)
Bituminous Coal-Fired Single Wall Boilers
after a statistical analysis these tests were not considered reoreser.ta'.i
tne boiler oooulation, and therefore not included in tne replacement emis
factor.
Fiqure 2-2.
Population histograms of NOX emission factors
for single wall utility boilers.
10
-------
4 -.
3 -
2-
1 -
Average
m m
m
VI i I |
70 80 90 100
-A, .
m
i
no
(200)
(230)
(260)
(290)
(320)
3 -
NO emission factors, lb/10 gal (ng/J)
a. Oil-Fired Cyclone Boilers
Average
. F
V
A
V
T\ 1 ra ,
t////x
30 35 40
1 I
(540) (720)
I I
45 50
1
(900)
VA
NO emission factors, Ib/ton (ng/J)
b. Bituminous Coal-Fired Cyclone Boilers
Figure 2-3.
Population histograms of NOX emission
factors for cyclone utility boilers.
11
-------
GJ
5 -
4 -
3 -
I 2
I 1
Average
Wm
15
20
(180)
(270)
(360)
NO emission factors, "ib/ton (ng/J)
Figure 2-4. Population histograms of NOX emission factors for
bituminous coal-fired tangential utility boilers.
Off-Stoichiometric Combustion (OSC) -- Some burners fire a
fuel-rich mixture and combustion is completed by injection of
additional air or lean mixture downstream
Flue Gas Recirculation (FGR) -- A portion of the flue gas is
recycled to the firebox
Load Reduction (LR) -- The boiler is fired at less than capacity
Combinations of two or more of the above
t
Low NO Burner (LNB)
/\
Much of the data on these controls have previously been analyzed by
Acurex (Reference 2-26). In addition to this review, a section of the
cyclone boiler report (Reference 2-21) considers the applicability of many
NO control techniques to this boiler type. The Standards Support and
A
Environmental Impact Statement report on lignite-fired boilers
(Reference 2-27) also dwells on certain of the N0x controls. Table 2-3
indicates the percent reduction one can expect by applying particular
NO control techniques to each boiler/fuel category.
12
-------
TABLE 2-3.' AVERAGE PERCENT REDUCTION OF NOX EMISSION FACTORS BY STATE-OF-THE-ART
CONTROL TECHNIQUES FOR UTILITY BOILERS (ENGLISH UNITS)
Type Boiler
Control
Techniques
Tangential
Baseline
LEA
OSC
FGR
LR
OSC + FGR
OSC + LR
OSC + LR + FGR
Horizontally
Opposed
Baseline
LEA
OSC
FGR
LR
OSC + FGR
OSC + IR
OSC + LR + FGR
LNB
NO Emissions (16 NO^/unit fuel consumed) as a Function of Fuel
Coal
Bituminous
NOX (Ib/ton)
15
12
9
13
8
25
22
20
20
22
15
19
15
% Reduction
20
40
*
15
*
45
*
10
20
20
10
40
25
*
40
Lignite
NOX { lb/ ton)
8
6
5
7
4
14
11
11
11
13
[8]
10
% Reduction
20
38
*
12
*
45
*
20
20-
20
10
[40]
25
*
Residual 01 1
NOX (lb/103 gal)
50
401
[40
35;
45
20
35'
35;
70
56
45
60
50
56
35
28
% Reduction
[20
[20
[30
[10
[60
[30
[30.
20
35
13
30
20
50
60
Natural Gas
NOX (lb/106 SCF)
300
210
300
120
300
[90]
[270]
[60]
700
600
300
[350]
300
[175]
140
100
(I Reduction)
--
30
0
60
0
[70]
ho
170]
15
60
[60]
60
[75]
80
85
'Indicates that no data Is available and technique may result In severe corrosion and/or slagging problems
[ ] Indicates engineering estimate
-------
TABLE 2-3. Concluded
Type Boiler
Control
Techniques
Single Mall
Baseline
LEA
OSC
FGR
LR
OSC + FGR
OSC * LR
LR + OSC + FGR
LNB
Cyclone
Baseline
LEA
OSC
FGR
LR
OSC + FGR
OSC t LR
OSC + LR + FGR
NO Emissions (Ib NO^/unlt fuel consumed) as a Function of Fuel
Coats
Bituminous
N0x (Ib/ ton)
19
16
13
14
10
11
36
25
% Reduction
--
IS
30
4
25
*
45
*
40
*
*
30
*
*
*
Lignite
NO (Ib/ton)
["]
CJ
[81
[6]
13
9
% Reduction
--
[20]
[30]
*
[25]
*
[45]
*
_-
4
3
Residual Oil
N0x (lb/103 gal)
50
31)
30
[35]
35
22
2B
22
87
78
[61]
70
% Reduction
_-
25
40
[30]
30
55
45
55
--
10
*
[30]
20
*
*
*
Natural Gas
N0x (lb/106 SCF)
410
350
210
270
125
105
80
165
660
[560]
330
[330]
(% Reduction)
__
15
50
35
70
75
80
60
..
[15]
*
50
[50]
*
*
*
Indicates that no data is available and technique may result in severe corrosion and/or slagging problems
[ ] Indicates engineering estimate
-------
It should be noted that off-stoichiometric combustion (OSC), also
known as two-staged combustion, can be accomplished by one of the
following:
Burners-Out-Of-Service (BOOS) -- Lower burners fire a fuel-rich
.mixture, while upper burners supply only combustion air
§ Biased Burner Firing (BBF) -- Lower burners simply fire a
richer fuel-air mixture than upper burners
t Overfire Air (OFA) -- All burners fire a richer mixture, then
additional combustion air is supplied above the firebox
The first two are generally used in a retrofit situation while the last is
principally a new boiler feature.
2.4 NITRIC OXIDE AS PERCENT CONSTITUENT OF TOTAL N0v EMISSIONS
A
Some data, principally from KVB (Reference 2-10 and 2-11) and the
cyclone boiler report (Reference 2-21) indicate that NO is the principal
constituent of NO . Of the four boiler categories for which either NO
A
or N0? were measured along with NO , NO constituted at least 95 percent
L. A
of the NO emissions. These data are presented in Table 2-4.
A
TABLE 2-4. NITRIC OXIDE AS A CONSTITUENT OF TOTAL NOX EMISSIONS
OF UTILITY BOILERS
Type
Boiler
Single wal 1
Cyclone
NO/NOX as a Function of Fuel3
Bituminous
Coal
96% (3)b
99% (6)
Residual
Oil
98% (1)
Natural
Gas
95% (2)
aWeight percentage, NO reported as N02
^Numbers in parentheses refers to number of boilers tested.
15
-------
REFERENCES FOR SECTION 2
2-1, Bartok, W., et al., "Systematic Study of NOX Emission Control Methods
for Utility Boilers," Exxon Report, GRU-4GNOS-71, December 1971.
2-2. Crawford, A. R., et al., "Field Testing: Application of Combustion
Modifications to Control NOX Emissions from Utility Boilers,"
EPA-650/2-74-066, NTIS-PB 237 344/AS, June 1974.
2-3. Dykema, 0. W., "Analysis of Test Data for NOX Control in Gas and
Oil-Fired Utility Boilers," EPA-650/2-75-012, NTIS-PB 241 918/AS,
January 1975.
2-4. Dykema, 0. W. and R. E. Hall, "Analysis of Gas-, Oil, and Coal-Fired
Utility Boiler Test Data," in Proceedings of the Stationary Source
Combustion Symposium, Volume III, EPA-600/2-76-152c, NTIS-PB 257
I46/AS, June 1976.
2-5. Bartz, D. R., et al., "Control of Oxides of Nitrogen from Stationary
Sources in the South Coast Air Basin," ARB 2-1471 (KVB Report No.
5800-179), September 1974.
2-6. Crawford, A. R., et al., "Field Testing: Application of Combustion
Modification to Power Generating Combustion Sources," Proceedings of
the Second Stationary Source Combustion Symposium, Volume II, Utility
and Large Industrial Boilers, EPA 600/7-77-073b, July 1977.
2-7. Thompson, R. E., et al., "Effectiveness of Gas Recirculation and Staged
Combustion in Reducing NOX on a 560 MW Coal-Fired Boiler," EPRI
Report No. FP-257, NTIS-PB 260 582, September 1976.
2-8. Crawford, A. R., et al., "Control of Utility Boiler and Gas Turbine
Pollutant Emissions by Combustion Modification Phase I,"
EPA-600/7-78-036a, March 1978.
2-9. Blakeslee, C. E., and A. P. Selker, Program for Reduction of NOX from
Tangential Coal-Fired Boilers, EPA-650/2-73-005, 5a and 5b, NTIS-PB 226
547/AS, PB 245 162/AS, PB 246 889/AS, August 1973, .June 1975 and August
1975.
2-10. Burrington, R. L., et al., "Overfire Air Technology for
Tangentially-Fired Utility Boilers Burning Western U.S. Coal,"
EPA-600/7-77-117, NTIS-PB 277 012/AS, October 1977.
2-11. Hollinden, G. H., et al., "NOX Control at TVA Coal-Fired Steam
Plants," ASME Air Pollution Control Division, in Proceedings of the
Third National Symposium, April 1973.
16
-------
2-12. Higginbotham, E. B. and P. M. Goldberg, "Field Testing of a Tangential
Coal-fired Utility Boiler -- Effects of Combustion Modification NOX
Control on Multimedia Emissions," Acurex Draft Final Report 79-337,
April 1979.
2-13. Crawford, A. R., £t aK_, "NOX Emission Control for Coal-Fired Utility
Boilers," Esso Research and Engineering Company. Paper presented at
the Coal Combustion Seminar, Research Triangle Park, North Carolina,
June 19-20, 1973.
2-14. Crawford, A. R., £t ^1_._, "The Effects of Combustion Modification on
Pollutants and Equipment Performance of Power Generation Equipment,"
Proceedings of the Stationary Source Combustion Symposium, Volume III,
nary b
, EPA-
Field Testing and Surveys, EPA-600/2-76-152c, June 1976.
2-15. Cato, G. A., et al., "Field Testing: Application of Combustion
Modifications to Control Pollution Emissions from Industrial Boilers --
Phase I," EPA-650/2-74-078a, NTIS-PB 238 920/AS, October 1974.
2-16. Cato, G. A., et al., "Field Testing: Application of Combustion
Modifications to Control Pollution Emissions from Industrial Boilers --
Phase II," EPA-600/2-76-086a, NTIS-PB 253 500/AS, April 1976.
2-17. Hollinden, G. H., et _a]_._, "Control of NOX Formation in Wall
Coal-Fired Boilers, in Proceedings of the Stationary Source Combustion
Symposium, Volume II, EPA-600/2-76-152b, NTIS-PB 256 321/AS, June 1976.
2-18. Hunter, S. C. and H. J. Buening, "Field Testing: Application of
Combustion Modifications to Control Pollutant Emissions from Industrial
Boilers Phase I and II (Data Supplement)," EPA-600/2-77-122, June
1977.
2-19. U.S. Environmental Protection Agency, "Supplement No. 6 for Compilation
of Air Pollutant Emission Factors," Office of Air Quality Planning and
Standards, AP-42, April 1976.
2-20. Maloney, K. J., "Western Coal Use in Industrial Boilers," Western
States Section/The Combustion Institute, Salt Lake City, Utah,
April 1976.
2-21. Ctvrtnicek, T. E. and S. J. Rusek, "Applicability of NOX Combustion
Modifications to Cyclone Boilers (Furnaces)," EPA-600/7-77-006, January
1977.
2-22. Unpublished Data, EPA 68-02-2160, Acurex Corporation, August 1978.
2-23. Maloney, K. L., et al., "Systems Evaluation of the Use of Low-Sulfur
Western Coal in "Existing Small and Intermediate-Sized Boilers,"
KVB Inc., EPA-600/7-78-153a, July 1978.
2-24. Gabrielson, J. E., £t jil_._, "Field Tests of Industrial Stoker Coal-Fired
Boilers for Emissions Control and Efficiency Improvement - Site A,"
KVB Inc., EPA-600/7-78-136a, July 1978.
17
-------
2-25. Gabrielson, J. E.. et al., "Field Tests of Industrial Stoker
Coal-Fired Boilers for Emissions Control and Efficiency Improvemer
- Site 3," KVB Inc., EPA-600/7-79-04ia, February 1979.
2-26. Lim, K. J., et al., "Environmental Assessment of Utility Boiler
Combustion Modification NOX Controls," Acurex Draft Report
TR-78-105, April 1978.
2-27. Goodwin, D. R., "Standards Support and Environmental Impact
Statement, Volume I: Proposed Standards of Performance for
Lignite-Fired Steam Generators," EPA-450/2-76-030a, December 1976.
18
-------
SECTION 3
INDUSTRIAL BOILERS
Industrial boilers, for the purposes of this study, are defined as
coal-, oil-, or gas-fired steam generators with rated heat input
capacities ranging from 2.9 to 29 MW (10 to 100 x 106 Btu/hr). These
units are generally packaged boilers, including small, stoker, coal-fired
units as well as oil (residual and distillate) or gas burning firetube and
watertube boilers. As in Section 2, subbituminous coal is included in the
bituminous category.
As with all general definitions, there are exceptions. In fact,
nearly 14 percent of the industrial boiler population have input
capacities greater than 73 MW and nearly 26 percent have input capacities
smaller than 2.9 MW (Reference 3-1). For purposes of this report those
industrial boilers which have rated heat input capacities greater then
29 MW were incorporated with the previous utility boiler review, and those
of less than 2.9 MW were designated as residential-commercial types,
Section 4.
3.1 NOY EMISSION FACTORS FOR INDUSTRIAL BOILERS
/\
Industrial boilers burning oil and natural gas have been divided
into two boiler types, watertube and firetube. A considerable quantity of
data much of it from the KVB reports were amassed for each category
(Tables 3-1 and 3-2). As before, Table 3-1 is presented in English units
and Table 3-2 contains the same data presented in SI units. Since
existing AP-42 emission factors for natural gas combustion are expressed
as a range, suggested replacement factors are expressed in the same
manner. Besides these results, the data also include Ultrasystems data
for a watertube and a firetube boiler tested with both natural gas and
residual oil (References 3-2 and 3-3) and Battelle data for a watertube
19
-------
TABLE 3-i. NOX EMISSION FACTORS SURVEY OF INDUSTRIAL BOILERS
{10 to 100 x 106 Btu/hr) (ENGLISH UNITS)
Baseline NOv Emissions as a Function of Fuel3
Type
Boiler
Water-tube
Firetube
Spreader
Stoker7"
[
i
Underfeed
Stoker^
1
Coal (Ib/ton burned) Oil (Ib/I03 gal)
!
Anthracite
Overfeed ! 16
j Stoker^ !
Bituminous
15
14 (3)
75!
15
9.5 (4)
-375!
15
7.8 (3)
-505!
Lignite
6.0
9 h
6.0
6.0
Residual
60t>
6QC (14)d
0X9
60
37 (6)
-38%
Distillate
22
19 (5)
-14%
22
21 (7)
-4%
Natural Gai; i
(lb/106 SC-) '
120-230
150 (13)
70-3106
120-230
110 (9)
65-150
N0x values reported in terms of NO. -
b01d AP-42 value
""Recommended replacement numoer based on new or revised data base
Number of boilers tested
eRange found for boilers tested
Stokers may be of either watertube or firetube construction
^Percent change in emission factor
[ ] Engineering estimate
EE-T-120
20
-------
TABLE 3-2. NOX EMISSION FACTORS SURVEY OF INDUSTRIAL BOILERS
(2.9 to 29 MW) (SI UNITS)
Type
Boiler
Water-tube
Firetube
Spreader
Stoker^
Underfeed
Stoker^
Overfeed
Stoker^
Baseline NOX Emissions (ng/J) as a Function of Fuel3
Coal
Anthracite
270
Bituminous
270
250 (3)
7%
270
170 (4)
-37%
270
140 (3)
-50%
Lignite
160
240 h
160
160
Oil
Residual
170b
170C (14)d
-6X9
170
110 (6)
-35X
Distillate
67
58 (5)
-18*
67
64 (7)
-3*
Natural Gas
49-94
60 (13)
30-1306
49-94
45 (9)
28-60
NO values reported in terms of NO-
b01d AP-42 value
cRecommended replacement number based on new or revised data base
Number of boilers tested
eRange found for boilers tested
Stokers may be of either watertube or firetube construction
^Percent change in emission factor
[ ] Engineering estimate
EE-T-121
21
-------
ana firetube boiler tested with natural gas, distillate oil and residual
oi1 (Reference 3-4).
Coal-fired industrial boilers are generally of the st ;ker design.
Pulverized coal units are limited to 29 MW (100 x 106 Btu/hr) as a
minimum size because of efficiency considerations (Reference 3-5). The
KVB data contain two spreader stokers, four underfeed stokers and one
overfeed stoker. A third spreader stoker and two overfeed units were
tested by Rockwell (Reference 3-6). These data for spreader stokers are
consistent-with utility boilers of the same category. The averages for
the underfeed and overfeed units appear reasonable. Based on the
bituminous coal NO emission factors for both spreader and underfeed
P\
stokers, a value of 9 Ib/ton (240 ng/J) is suggested rather than the
6 Ib/ton (160 ng/J) currently employed. The underfeed stoker lignite
value, however, should be retained. Also there are not enough data for
lignite coal-fired spreader stokers to improve on the existing overfeed
stoker NO emission value for lignite.
3.2 HISTOGRAMS OF NO EMISSIONS FOR INDUSTRIAL BOILERS
A
Figure 3-1 shows bar graphs of baseline emission valuer versus
class of boiler for those classes in which more than two NO emission
numbers were gathered. The variation within each boiler anc "uel category
may be due to .load (not all baselines were run at 80 percent load), air
preheat, burner type, furnace dimensions, differences in fuel nitrogen,
amount of excess air, errors in measurement, to name a few. Because of
the number of variables, the data are presented to only two significant
figures. All baseline data found were included.
3.3 NITRIC OXIDE AS PERCENT CONSTITUENT OF TOTAL NO EMISSIONS
A
The total nitrogen oxides (NO ) emissions consist primarily of
A
two components: Nitrogen dioxide (N02) and nitric oxide. T;-.JS, if the
concentration of two are known, the third can be determined to some degree
of accuracy.
KVB determined NO and N0v on almost all boilers te':sd during its
/\
two field investigations. Table 3-3 contains this data reduced to percent
NO in NO . As can be seen, the average percent NO in NO, is at least
A '.
94. The ratio of NO to NO does not seem to be affected :-y fuel type or
A
boiler type or size.
22
-------
4 -l
nj-n Average
A '//.7/7X//M/A/// V/\
100 150
I
(40)
200 250
1
(80)
5
i
'//VA V/A
300
1
(120)
NO emission factors, lb/106 scf (ng/J)
a. Natural Gas-Fired Front Wall Watertube Units
U1
c
=>
w
o
HI
.0
3
4 -i
3 -
9
l
Aver
i
///[/// K//1 I//I 7/1
age
7A V//VA
V ' 1 I
50 75 100 125
\ . .
s
4
P
<:
150
(20)
(30)
(40)
(50)
/I -.
3 -
1 -
NO emission factors, lb/10 scf (ng/J)
b. Natural Gas-Fired Front Wall Firetube Units
Average
1 f^
7/VA
V 1 i
15 20
A.
V/fl/A,
25
(55)
(70)
NO emission factors, lb/10 gal (ng/J)
c. Distillate Oil-Fired Front Wall Watertube Units
(60)
Figure 3-1.
Population histograms of NOX emission factors
for industrial boilers.
23
-------
Average
m m
(80)
iNO emission factors, lb/10 gal (ng/J)
Distillate Oil--ired Front Wall Firetube Units
Average
:no)
25
i
22
W
m
//](///
tWt
WL
m m
iii
50 75 '00 125
1 1
(200) (330)
NC emission factors, lb/10^ gal (ng/J)
e. Residual Oil-Fired Front Wall WatertuDe Units
Average
m
-V-i
40
50
dob)
(120) . ..
NO emission ^actors, lb/10 gal (ng/J)
*'. Residual Oil-^irea Front Wall Firetube Units
Figure 3-1. Continued.
24
-------
4 -i
3 -
2 -
1 _
Ave
. m i
rage
V i i
10 15
n
j
H
«c
20
(180)
(270)
NO emission factors, Ib/ton (ng/J)
A
g. Bituminous Coal-Fired Spreader Stokers
4
3
2 -
1 -
Average
wm M
\
5
i
(90)
I
10
(180)
1
15
(270)
NO emission factors, Ib/ton (nq/J)
A
h. Bituminous Coal-Fired Underfeed Stokers
Figure 3-1. Concluded.
25
-------
TABLE 3-3. NITRIC OXIDE AS A CONSTITUENT OF TOTAL NOX EMISSIONS
OF INDUSTRIAL BOILERS
Type
Boiler
Watertube
Firetube
Spreader
Stoker
Underfeed
Stoker
NO/NOX as a Function of Fuel3
Bituminous
Coal
98% (2)
93% (4)
Residual
Oil
99% (12) a
98% (4)
Distillate
Oil
97% (3)
95% (5)
Natural
Gas
95% (8)
94% (9)
aWeight percentage, NO reported as ';02
^Numbers in parentheses refers to number of boilers tested
26
-------
3.4 EFFECT OF CONTROLS ON NO EMISSIONS FOR INDUSTRIAL BOILERS
A
No long term testing of state-of-the-art NO emission controls
A
has yet been undertaken for industrial boilers. Because of this, it is
difficult to say whether the NO control techniques developed for
A
utility boilers will be equally effective for industrial boilers. Short
term tests by KVB and others do indicate, however, that combustion
modification control techniques are effective in reducing NO
A
(References 3-7, 3-8, 3-2 and 3-3). It is not yet recommended that these
limited controlled emissions data be published in AP-42.
3.5 OTHER DATA
One data source for coal-fired boilers which met the requirements
for inclusion in the survey was that of Ferrari (3-9). However, the data
are presented separately for two reasons:
t The source of the data is Australia and, although the boilers
may be basically the same, some may be different in design.
t Where the data overlaps the data in this study; they are quite
different and generally do not follow the expected trend with
unit size.
Table 3-4 lists Ferrari's values and compares them with averages
for all of the boiler types for which the design is specified. Ferrari
also reported on pulverized coal units but failed to indicate the type of
units tested. However, his results for pulverized coal are considerably
lower than the averages for tangential, single wall and horizontally
opposed boilers in the utility category.
27
-------
TABLE 3-4. COMPARISON OF DATA FROM FERRARI et al. WITH CALCULATED
AVERAGES FOR SAME BOILER TYPE AND SIZE
Type Unit
Chain Grate Stokers
(overfeed)
Spreader Stokers
NOX emission factors (ng/J)
as function of boiler size
Utility
141 (4)a
166
260 (5)
Industrial
137 (2)b
HOC (3)
192 (2)
250 (3)
Top row Ferrari's values.
Numbers in parentheses refer to number of boilers tested,
'Bottom row, NO emissions update averages.
X
28
-------
REFERENCES FOR SECTION 3
3-1. ."Task 2 Summary Report -- Preliminary Summary of Industrial Boiler
Population," prepared by PEDCo in support of OAQPS work on NSPS for
industrial boilers, June 29, 1978.
3-2. Cichanowicz, J. E., et al., "Pollutant Control Techniques for Package
Boilers. Phase I -- Hardware Modifications and Alternate Fuels,
Ultrasystems Draft Report for EPA 68-02-1498, November 1976.
3-3. Heap, M. P., et al., "Reduction of Nitrogen Oxide Emissions from Field
Operating Package Boilers, Phase III," EPA-600/2-77-025, NTIS-PB 269
277, January 1977.
3-4. Barrett, R. E. and S. E. Miller, "Field Investigation of Emissions from
Combustion Equipment for Space Heating," Battelle-Columbus Laboratories,
EPA-R2-73-084a, API Publication 4180, June 1973.
3-5. "Task 7 Summary Report -- Technical and Economic Bases for Evaluation of
Emission Reduction Technology," prepared by PEDCo in support of OAQPS
work on NSPS for industrial boilers, June 2, 1978.
3-6. Littman, F. E., et al., "Regional Air Pollution Study. Point Source
Emission Inventory," EPA-600/4-77-014, March 1977.
3-7. Cato, G. A. et al., "Field Testing: Application of Combustion
Modifications to Control Pollutant Emissions from Industrial Boilers --
Phase 1," EPA-600/2-74-078a, NTIS-PB 238 920/AS, October 1974.
3-8. Cato, G. A. et al., "Field Testing: Application of Combustion
Modifications to Control Pollutant Emissions from Industrial Boilers --
Phase 2," EPA-600/2-76-086, NTIS-PB 253 920/AS, October 1974.
3-9. Ferrari, L. M., et al., "Nitrogen Oxides Emissions and Emission Factors
for Stationary Sources in New South Wales," International Clean Air
Conference, The Clean Air Society of Australia and New Zealand," May
1967.
29
-------
SECTION 4
COMMERCIAL AND RESIDENTIAL UNITS
This section not only covers all stationary steam generating
sources whose rated heat input capacity is less than 2.9 MW (< 10 x 10
Btu/hr) but also residential hot water, steam and forced air heaters. The
arbitrary dividing line between commercial and residential units is set at
150 kW (5 x 10 Btu/hr). As noted previously in the introduction to
industrial boilers, nearly 26 percent of the boilers used in industry have
input capacities less than 2.9 MW. Thus, some commercial boiler data were
obtained from industrial boiler reports.
4.1 NO EMISSION FACTORS FOR COMMERCIAL SIZED BOILERS
/\
Commercial boilers fall into three categories: stoker fed
coal-fired, hand fed coal-fired, and oil- or gas-fired units generally of
a firetube design. Many are used as a source of hot water rather than' a
source of steam or electricity. Tables 4-1 and 4-2 contain information on
those units whose NO emissions have been measured.
X
The initial KVB boiler survey (Reference 4-1) contains data on two
firetube boilers with heat input capacities of 2.1 MW (7 x 10 Btu/hr)
and 2.4 MW (8 x 10 Btu/hr). One of these units was run with two grades
of residual oil, distillate oil and natural gas. The other was run with
natural gas only. The oil data have previously been incorporated into
AP-42, supplement 6 (Reference 4-2). The natural gas data are 22 percent
lower than the existing AP-42 number which is composed solely of the
results from seven boilers tested by Battelle (References 4-3 and 4-10).
However, two of these Battelle units were industrial size and the data
have been recalculated to reflect this. Thus, the new value is the
arithmetic average of the remaining five units plus the two KVB results.
30
-------
TABLE 4-1. NOX EMISSION FACTORS SURVEY OF COMMERCIAL STATIONARY STEAM AND HOT WATER
GENERATING UNITS (0.5 to 10 x 106 Btu/hr) (ENGLISH UNITS)
Type
Boiler
Firetube
Commercial
Stokers
Commercial
Hand-Fired
Units
Baseline NOX Emissions as a Function of Fuel9
Coal (Ib/ton)
Anthracite
2.2-3.2f (1)
3
Bituminous
6.0
3.0
Lignite
6.0
Oil (lb/l()3 gal)
Residual
60b
6ic (8)d
2e
Distillate
22
19 (7)
-14%
Natural Gas
(lb/106 SCF)
120
92 (7)
-22%
aNO values reported in terms of NO-
D01d AP-42 value
'Recommended replacement number based on new or revised data base
Number of boilers tested
^Percent change in emissions factor
Range as reported in literature, best available information (Reference 4-5)
-------
TABLE 4-2. NOX EMISSION FACTORS SURVEY OF COMMERCIAL STATIONARY STEAM
AND HOT WATER GENERATING UNITS (0.15 to 2.9 MW) (SI UNITS)
Type
Boiler
i
i
Firetube
Commercial
Stokers
Commercial
Hand-Fired
Units
Basline NOX Emissions (ng/J) as Function of Fueia
Coal
Anthracite
37-55(l)f
51
Bituminous
110
54
Lignite
160
Oil
Residual
172°
180C (8)d
2e
Distillate
67
58 (7)
-15%
Natural Gas !
1
49
38 (7)
-22*
i
aNO values reported in terms of NO-
b01d AP-42 value
cRecommended replacement number based on new or revised data base
,1
Number of boilers tested
ePercent change in emissions factor
Range as reported in literature, best available information (Reference 4-5)
EE-T-119
32
-------
Battelle (Reference 4-3) has also tested a 200 kW commercial boiler
fitted with both bituminous and anthracite stokers. This unit was
operated at extremely low loads for most of the test sequences in an
attempt to achieve smokeless results. The NO emission factors reported
A
here for anthracite were run at 74 percent load and the bituminous at 49
percent load. Because of the low load and large excess air conditions,
incorporation of the bituminous coal data in AP-42 is not recommended and
have not been included in the reported average.
4.2 N0v EMISSION FACTORS FOR RESIDENTIAL FURNACES AND BOILERS
A
Residential units fall into the same broad categories as the
commercial boilers, above. NO emission data for residential units
n
are contained in Tables 4-3 and 4-4, in English units and SI units,
respectively.
Monsanto (Reference 4-6) has recently published information on a
200,000 Btu/hr furnace and a 200,000 Btu/hr boiler. Both units are
supplied by underfeed stokers and fired with western subbituminous coal.
Average baseline NO for the two units is 8.5 Ib/ton (152 ng/J). The
A
NO emission factors were approximately twice as great for the furnace
A
as for the boiler using the same coal. This suggests that design features
may play an important part in NO emission factors for these units.
A
Several recent sources of data on NO emissions for natural
/\
gas-fired residential units have been abstracted (References 4-7, 4-8, and
4-9). The most extensive results, conducted by The American Gas
Association (AGA) Laboratories (Reference 4-7) cover 38 gas-fired, forced
air furnaces manufactured by 29 different companies with heat input rates
3 3
ranging from 75 x 10 to 180 x 10 Btu/hr. The average NOX emission
factors for these units are 103 Ib N02/105 scf (42.1 ng N02/J) and
they ranged from 18.8 to 128.1 Ib N02/106 scf (7.7 to 52.5 ng N02/J).
The lowest number was considered outside of acceptable limits and was
discarded for the final average. The data for the blue flame, high 02
condition, were considered as baseline. A second, low excess air (yellow
flame adjustment) testing sequence showed an average 10 percent decrease
in NO emissions for this control technique.
A
Hall (Reference 4-8) reports on the testing of two gas-fired
furnaces and one gas-fired boiler. In these tests NO measurements
averaged 60.5 Ib NO/106 scf (24.8 ng NO/J). If one assumes that at
33
-------
TABLE 4-3. NOX EMISSION FACTORS SURVEY OF RESIDENTIAL STEAM AND
HOT WATER GENERATING UNITS (<500,000 Btu/hr)
(ENGLISH UNITS)
Typ*
Boiler
Residential
Heating
Stoker
Units
Hand-Fired
Units
Baseline NOX Emissions as a Function of Fuel3
Coal (Ib/ton)
Anthracite
6.0
8.5 (2)
42X
3. Ob
Bituminous
6.0
Lignite
Oil (lb/103 gal)
Residual
Distillate
18
Natural Gas
(lb/100 SCF)
80*>
102C (44)d
+28X*
NO values reported in terms of NO.
b01d AP-42 value
cRc-commended replacement number based on new or revised data base
N'.moer of boilers tested
P="cent change in emissions factor
EE-T-122
-------
TABLE 4-4. NOX EMISSION FACTORS SURVEY OF RESIDENTIAL (<0.15 MW)
- STEAM AND HOT WATER GENERATING UNITS (SI UNITS)
Type
Boiler
Residential
Heating
Stoker
Units
Hand-Fired
Units
Baseline NOX Emissions (ng/J) as a Function of Fuel3
Coal
Bituminous
107
152 (2)
42%
54b
Lignite
160
Oil
Residual
Distillate
55b
Natural Gas
33 b
42C (44)d
+28%e
CO
en
NO values reported in terms of N02
b01d AP-42 value
GRecommended replacement number based on new or revised data base
Number of boilers tested
Percent change in emissions factor
-------
least 90 percent of NO is NO then the NO concentration (measured in
terms of N02) is 102 ib N02/105 scf (41.8 ng N02/J). The units
tested by Hall were "as is." Those by the AGA were tuned (blue flame).
In both cases, the tests were considered baseline. Similar lack of
effects of boiler tuning on NO emissions were shown by KVB for
/\
industrial boilers (Reference 4-10).
Finally, Rocketdyne (Reference 4-9), prior to testing various
modifications on the unit, procured and tested a Lennox 011-140 warm air
furnace equipped with a stock Lennox Burner. A baseline run on the unit
gave 98 Ib NO/106 scf (40 ng NO/J). This is equivalent to 167 Ib
N02/106 scf (68 ng N02/J) of N0x measured as N02 if the NO as
measured previously accounted for 90 percent of the NO .
A
Summation of these 41 individual boilers with the two units
previously averaged in AP-42 Supplement 3 (Reference 4-11) gave 102 Ib
N02/10 scf (42.0 ng/J) as the overall average.
4.3 NOV EMISSION FACTORS FOR PILOT LIGHTS
X
Most residential, gas-fired waterheaters and forced air furnaces
contain pilot burners. Fuel input ranged from 828 to 1570 Btu/hr for the
seven pilot lights examined by the AGA (Reference 4-7). The average NO
emission factor for these pilots is 71.3 lb/106 scf (29.2 ng/J), roughly
75 percent of that for the burners.
4.4 HISTOGRAMS OF N0v EMISSIONS FOR COMMERCIAL AND RESIDENTIAL UNITS
X
Population NO emission histograms are drawn for gas-fired
A
commercial boilers, residential heating units and pilot lights. These
histograms are shown in Figure 4-1. All data are within acceptable limits
except the 7.7 ng/J residential unit reported by Thrasher and Dewerth
(Reference 4-7).
4.5 NITRIC OXIDE AS PERCENT CONSTITUTENT OF TOTAL NOV EMISSIONS
X
Much of the data reviewed was reported in terms of either NO and
NO? or NO and NO . These data are presented in Table 4-5. A trend in
£ A
the data seems to indicate that the smaller the source, the greater the
fraction of NO in the NO emissions. The pilot light data and 38 data
A
points for gas-fired residential units were reported by the American Gas
Association Report (Reference 4-7). The remaining N0/N02 data were
taken from two older Battelle documents (Reference 4-3 and 4-4). Data for
commercial units were reported by Battelle (Reference 4-3) and KVB
(Reference 4-1).
36
-------
5-
4-
3-
2-
i _
i
Average
V*
^ '//A //A//.
"
p
// Y//\
VI I I i i i
10 20 30 40 50 -. 60
I i 1
50 100 15
7 -,
3-
CJ
-e 2-
Emission factor, ng/J (Ib x 10 scf)
a. Natural Gas-Fired Commercial Boilers
m
10
20
30
40
50
Emission factor, ng/J (Ib x 10 scf)
b. Natural Gas-Fired Residential Units
60
1
50
! 1
100 1!
4-
3-
1 -
0
Aver
\
₯/$//////_
10 20 3(
age
n
//i
^
i i
3 40 50
i i
50 100
Emission factor, ng/J (16 x 10 scf)
c. Pilot Lights
Figure 4-1. Population histograms of NO* emission factors for
natural gas-fired commercial boilers, residential
units, and pilot lights.
37
-------
TABLE 4-5. NITRIC OXIDE AS A CONSTITUENT OF TOTAL NOX EMISSIONS
OF COMMERCIAL AND RESIDENTIAL BOILERS AND HEATING UNITS
AND PILOT LIGHTS
Type
Boiler
Commercial
0.5 to 10 x 106
Btu/hr
Residential
2 to 500 x 10 3
Btu/hr
Pilot Light
<2000 Btu/hr
NO/NOX as a Function of Fuel3
Natural
Gas
97 (8)b
As found
79 (2)
Tuned
95 (38)
55 (7)
Distillate
Oil
99 (7)
75 (32)
Residual
Oil
99 (7)
Weight percentage, NO reported as N09
£
Numbers in parentheses refers to number of boilers tested,
38
-------
REFERENCES FOR SECTION 4
4-1. Cato, G. A. et al., "Field Testing: Application of Combustion
Modifications to Control Pollutant Emissions from Industrial
Boilers Phase I," EPA-600/2-74-078a, NTIS-PB 238 920/AS,
October 1974.
4-2. U.S. Environmental Protection Agency, "Supplement No. 6 for Compilation
of Air Pollutant Emission Factors," Second Edition, Office of Air
Quality Planning and Standards, Document AP-42, April 1976.
4-3. Barrett, R. E., et al., "Field Investigation of Emissions from
Combustion Equipment for Space Heating," EPA-R2-73-084a (API
Publication 4180), June 1973.
4-4. Levy, A., et al., "A Field Investigation of Emissions from Fuel Oil
Combustion for Space Heating," API Publication 4099, November 1971.
4-5. Giammar, R. D., et al., "Emissions from Residential and Small
Commercial Stoker-Coal-Fired Boilers Under Smokeless Operation,"
EPA 600/7-76-029, October 1976.
4-6. DeAngelis, D. G., and R. B. Reznik, "Source Assessment: Coal-Fired
Residential Combustion Equipment Field Tests, June 1977, "EPA
600/2-78-0040, June 1978.
4-7. Thrasher, W. H. and D. W. Dewerth, "Evaluation of the Pollutant
Emissions from Gas-Fired Forced Air Furnaces," American Gas Association
Research Report #1503, Catalog No. U7815, May 1975.
4-8. Hall, R. E., et al., "A Study of Air Pollutant Emissions from
Residential Heating Systems," EPA 650/2-74-003, January 1974.
4-9. Combs, L. P., and A. S. Okuda, "Residential Oil Furnace System
Optimization, Phase II," EPA 600/2-77-028, January 1977.
4-10. Cato, G. A., et al., "Field Testing: Application of Combustion
Modifications to Control Pollutant Emissions from Industrial Boilers
Phase 2," EPA-600/2-76-086a, NTIS-PB 253 500/AS, April 1976.
4-11. U.S. Environmental Protection Agency, "Supplement No. 3 for Compilation
of Air Pollutant Emission Factors," Second Edition, Office of Air
Quality Planning and Standards, Document AP-42, July 1974.
39
-------
SECTION 5
STATIONARY RECIPROCATING ENGINES
Reciprocating engines consist of two major subclasses, compression
ignition (CI) and spark ignition (SI). Each subclass is divided into
two-stroke and four-stroke engine cycle categories (Reference 5-1).
Further division by engine use has also been customary (Reference 5-2 and
5-3); however, because engine type and size are constantly changing within
each use category, the substitution of rated power output is recommended.
5.1 NOV EMISSION FACTORS FOR COMPRESSION IGNITION ENGINES
/\
These engines are divided into three power output categories; large
(>75 kW/cyl), medium (75 kW/cyl to 75 kW/engine), and small (<75 kW/engine)
Further division is by fuel type and by engine cycle. Two fuel types are
characteristic of compression ignition engines; diesel engines, burning
diesel oil fuel, and dual fuel engines, burning a mixture of diesel oil
and gas (natural and synthetic) consisting of anywhere from >95:5 to
<5:95 parts by weight of the two fuels. Some dual fuel engines also have
the capability of burning each fuel separately.
Table 5-1 gives the emission factors in 3 different units. To
convert from output specific units, e.g., gm/hp-hr, to input specific
3 3
units, e.g., ng/J and Kg/10 liter or lb/10 gal, heat rates for
compression ignition engines were estimated. These are presented in Table
5-2.
The nitrogen oxides emissions factors for large and medium CI
engines were reported in the Standards Support Document (Reference 5-1)
and Hare and Springer (Reference 5-4). NO emission factors for small
engines were found in Marshall and Fleming (Reference 5-5) in addition to
Hare and Springer.
40
-------
TABLE 5-1. BASELINE NOX EMISSION FACTORS SURVEY OF RECIPROCATING
COMPRESSION IGNITION (CI) ENGINES
Engine
Size
Large
>75 kW/cyl.
Medium
75 kW/eng.
-75 kW/cyl.
Small
<75 kW/eng.
Units
ng/Jb
g/hp-hr
lb/103 galb
No. Engines
ng/Jb
g/hp-hr
lb/103 galb
No. Engines
ng/Jb
g/hp-hr
lb/103 galb
No. Engines
NOX Emissions as a Function of Stroke and Fuela
Diesel oil
2 Stroke
1800
13.3
600
(14)
1980
16.1
660
(23)
4 Stroke
1200
8.8
400
(19)
1100
9.0
360
(66)
1300
10.5
430
(15)
Dual Fuel
2 Stroke
1520
10.4
__c
(3)
4 Stroke
1260
8.6
__c
(6)
NO.
values reported in terms of N0?
Input Specific
"Constituent ratio of dual fuel unknown
41
-------
TABLE 5-2. HEAT RATES FOR COMPRESSION IGNITION ENGINES
Engine Size
Large
Medium and Small
Fuel
Diesel
Dual
Diesel
Heat Rate (Btu/hp-hr)
7000 (Reference 5-1)
6500 (Reference 5-1)
7680 (Reference 5-3)
AP-42, Supplement 4 previously lists Hare and Springer data without
differentiation as to size or number of strokes per firing cycle.
5.2 NO EMISSION FACTORS FOR SPARK IGNITION ENGINES
/\
Spark ignition (SI) engines are divided into four categories of
power output; large ( >75 kW/cyl), medium (75 kW/cyl to 75 kW/engine),
small (15-75 kW/engine) and very small (<15 kW/engine). Like compression
ignition engines, these engines, are further divided by engine cycle and
fuel type. The principal fuels for spark ignition engines are gasoline
and natural gas. Table 5-3 contains the average NO emissions factors
/\
for these engines.
A substantial body of data was acquired for natural gas-fired large
and medium sized, stationary, spark ignited (SI) engines (References 5-1,
5-6, 5-7, and 5-8). The current emission factors are 20 percent higher
for two-stroke engines and 40 percent higher for four-stroke engines than
those in AP-42, which are based on Urban and Springer and Dietzman and
Springer alone (Reference 5-6 and 5-7). The best data available were
considered to be that of Dietzman and Springer which were repeated in
Urban and Springer. These were used in the averages in Table 5-3. These
data agreed well with that abstracted from References 5-1 and 5-6.
Data for gasoline fired SI engines were obtained for all categories
except large engines (References 5-4, 5-9, 5-10, and 5-11). Numbers for
the small and very small engine categories are from Hare and Springer
(Reference 5-4). They have previously been abstracted into AP-42 under
"industrial equipment", Section 3.3.3, and "small, general utility
engines", Section 3.2.5. There are no additional data in these
categories, but a minor adjustment was necessary. The values reported
42
-------
TABLE 5-3. BASELINE NOX EMISSION FACTORS SURVEY OF RECIPROCATING
SPARK IGNITION (SI) ENGINES
Engine
Size
Large
>75 kW/cyl.
Medium
75 kW/eng.
-75 kW/cyl.
Small
15-75 kW/eng.
Very Small
<15 kW/eng.
Units
ng/jb
g/hp-hr
lb/103 galb
lb/10b SCFb
No. Engines
ng/jb
g/hp-hr
lb/103 galb
lb/10b SCFb
No. Engines
ng/jb
g/hp-hr
lb/103 galb
No. Engines
ng/Jb
g/hp-hr
lb/103 galb
No. Engines
NOX Emissions as a Function of
Stroke and Fuela
Gasoline
4 Stroke
740
10.8
260
9
310
5.4
110
3
198
5.0
69
5
Natural Gas
2 Stroke
1660
13.2
4000
55
4 Stroke
1960
15.5
4800
24
1600
12.7
3900
23
aNO values reported in terms of N0?
. X c.
Input specific values, all others are output specific
43
-------
herein are computed on an evenly weighted average and one engine that was
not tested at baseline was deleted.
5.3 HISTOGRAMS OF NO EMISSIONS FOR RECIPROCATING ENGINES
^
Population versus NO emission factor histograms were drawn for
/\
all of the categories of SI and CI engines for which data were obtained.
They appear in Figure 5-1 through 5-4. Two of the histograms contain
blocks with numbers superimposed on them. These blocks represent averages
of a particular number of engines as reported in the literature; values
for the individivual tests were not given. Abscissae of these plots are
marked in both English and SI units where possible.
5.4 NITRIC OXIDE AS PERCENT CONSTITUTENT OF TOTAL NO EMISSIONS
A
Data for percent NO in total NO were taken from Hare and
^
Springer, Dewerth, and Dietzman and Springer (References 5-4, 5-6, and
5-8). It is presented by engine subclass and category in Table 5-4.
44
-------
Averaqe
A
A' 1
500
V/M
1000
«pd
I
VA Y//xm m
1500 2000 2500
(200) (300) (400) (500) (600) (700)
NO emission factors, ng/J (lb/10 gal)
a. Large 2-Stroke
(800) (90C)
o
V-
5 -,
4 -
3 -
2 -
1 -
Average
m m
'///
7/<
f/t
//<
\
y/<
Y/t
'M
y//
y//
Y/t
-------
6 -
4 -
3 -
2-
1 -
0
y/t
tfs
///
w\
Sfy
%
' //
^
3
W
^
6
5
4
Average
T
P
ft
f / /
fy/
5
4
f /£
'///
V/f
y/t
5
£
*
2 22
500
1000
i SCO
2000
200
00
600
NO enission factors, nq/J (lb/'10J cal)
d. Medium, 4-Stroke
D ~
4 ""
1 -
0
Aver
j
WA 7f///j'/i '//////%////.
500 1000
200 400
age
ty/A V////A
WM m
1500 2000 250C
600
800
NO emission factors. ng/J (lb/10 gal)
e. Small, ^-Stroke
*Numbers in blocks indicate averages of this number of ennines as reported
in the literature. Shaded blocks indicate individual enoines.
Figure 5-1. Concluded.
45
-------
3-j
2 _
1 ~ . ,.L
^ f^
Average
1
K51
l/l
01
c
1000
1500
2000
2500
NO emission factors, ng/J
X
Large, 2-Stroke
CJ
JO
3
2
1
Average
rj
<
S
500 1000 1500
NO emission factors, ng/J
Large, 4-Stroke
2000
Figure 5-2.
Population histograms of NOX emission factors for
compression ignition engines firing dual fuels.
47
-------
500
TOGO
1500
?000
2500
3000
I
(2000)
I
(4000)
(6000)
NO emission factors, ng/J (lb/10 scf)
x
a. Larne Size, 2-?trokp
Averaae
(EOOO)
m
1000
1500
2000
2500
3000
I T
(400C! (COCO!
NO emission factors, ng/J (lb/10 scf)
b. Large Size, 4-Stroke
Averaae
J 1
4 -
3 -
2 -
0
m m m m
m
'//
//ft
/A
%
500 1000
(1000) (3000)
\
/' i
///
>/ 1
//
^
m
1 1
'//
TJ
'//
'///
i
UL
7/,
1 1
//
* t /
i
1500 2000 2500
(5000)
NO emissions factors, ng/J (Ib/"!? scf)
c. Medium Size, 4-Stroke
Figure 5-3. Population histograms of NOX emission factors for stationary
reciprocating, natural gas firing SI engines.
48
-------
4 -,
3 -
2 -
1 -
0
Average
i
m m
'//
m
7i\ n
//
m m -
200
300
(500)
(600)
(700)
(800)
(900)
NO emission factors, lb/10 gal (ng/J)
a. Medium
m
V
\
(200)
Ave
i
i
100
I
(300)
rane
w,
1
150
1
(400)
w\
1
(500)
O emission factors, 1b/10° gal (ng/J)
b. Small
(1000)
3 -
2 -
1 -
0
Average
m m vfl v\ m
50
i i
(100) (200)
100
i i
(300) (400;
enission factors, lb/10 gal (nn/j)
c. Very Smal 1
Figure 5-4.
Population histograms of NOX emission factors for stationary
reciprocating gasoline fired Spark Ignition engines.
49
-------
TABLE 5-4. NITRIC OXIDE AS A CONSTITUENT OF TOTAL NOX EMISSIONS
OF RECIPROCATING ENGINES
Engine
Size
Large
Medium
Smal 1
NOX Emissions as a Function of Type, Stroke, Fuel and Size9
Compression Ignition
Diesel Fuel
2 Stroke
93 (1)
4 Stroke
96 (4)
98 (3)
*
Spark Ignition
Natural Gas
2 Stroke
88 (42)b
4 Stroke
83 (9)
96 (15)
f
Gasoline
98 (3)
^Weight percentage, NO reported as NOp
'Number in parentheses refers to number of engines tested
50
-------
REFERENCES FOR SECTION 5
5-1 Youngblood, S. B. et al., "Standards Support and Environmental Impact
Statement for Reciprocating Internal Combustion Engines," Acurex Draft
Report TR-78-99, March 1978.
5-2 Anon, "Compilation of Air Pollution Emission Factors," U.S.
Environmental Protection Agency, Office of Air Quality Planning and
Standards, Publication AP-42, April 1973 and.Supplements.
5-3 Shimizu, A. B., et al., "NOX Combustion Control Methods and Costs for
Stationary Sources -- Summary Study," EPA 600/2-75-046, September 1975.
5-4 Hare, C. T. and K. J. Springer, "Exhaust Emissions from Uncontrolled
Vehicles and Related Equipment Using Internal Combustion Engines, Final
Report Part 5, Heavy-Duty Farm, Construction and Industrial Engines,"
Southwest Research Institute, San Antonio, Texas, AR-898, October 1973.
5-5 Marshall, W. F. and R. D. Fleming, "Diesel Emissions Reinventoried,"
Report of Investigations No. 7530 by the U.S. Department of the
Interior, Bureau of Mines, 1972.
5-6 Dietzmann, H. E., and K. J. Springer, "Exhaust Emissions from Piston and
Gas Turbine Engines Used in Natural Gas Transmission," Southwest
Research Institute, San Antonio, Texas, prepared for American Gas
Association, Arlington, VA, January 1974.
5-7. Urban, C. M. and K. J. Springer, "Study of Exhaust Emissions from
Natural Gas Pipeline Compressor Engines," Southwest Research Institute,
San Antonio, Texas, prepared for American Gas Association, Arlington,
VA, February 1975.
5-8 Dewerth, D. W., "Air Pollutant Emissions from Spark-Ignition Natural Gas
Engines and Turbines," American Gas Association Laboratories Research
Report No. 1491, September 1973.
5-9 Hare, C. T. and K. J. Springer, "Exhaust Emissions from Uncontrolled
Vehicles and Related Equipment Using Internal Combustion Engines, Final
Report, Part 4, Small Air-Cooled Spark Ignition Utility Engines," U.S.
Environmental Protection Agency, APTD-1493, May 1973.
5-10 Fleming, R. D. and F. R. French, "Durability of Advanced Emission
Controls for Heavy Duty Diesel and Gasoline Fueled Engines,"
EPA 460/3-73-010, September 1973.
5-11 Springer, K. J., "Baseline Characterization and Emissions Control
Technology Assessment of Heavy-Duty Gasoline Engines," Final Report
Southwest Research Institute, San Antonio, Texas, AF-844, November 1972.
51
-------
SECTION 6
GAS TURBINES
6.1 NOX EMISSION FACTORS FOR VARIOUS TYPES AND SIZES OF GAS
TURBINE ENGINES
For the purpose of this study, gas turbines have been divided into
three sizes: large >15 MW (>20,000 hp), medium, 4 to 15 MW (5300 hp to
20,000 hp) and small, <4 MW (<5300 hp). The units were further divided
into simple and regenerative cycle* and subsequently classified as to
fuel. As no distinction could be made between the various types of oil
burned, all of these were combined into liquid fuel. The liquid fuel
category does not contain derived fuels such as methanol but does include
heavy distillates and crudes when reported.
Table 6-1 contains a summation of the data extracted. Much of the
information was obtained from the Standard Support Document (Reference 6-1)
Other sources include Dietzman and Springer (which has already been
incorporated into Supplement 6 of AP-42) (Reference 6-2), Dewerth
(Reference 6-3), Wasser (Reference 6-4), Crawford, et a!., (Reference 6-5)
and Acurex (Reference 6-6). Much of the data contained heat rates for the
units tested so that it was possible to determine input specific (Ib/MBtu,
ng/J, lb/10 scf or lb/10 gal) as well as output specific (ppm at 15
percent 02, Ib/MWH, g/hp-hr) NOX emission terms.
6.2 HISTOGRAMS OF N0₯ EMISSIONS FOR GAS TURBINE ENGINES
A
Figure 6-1 shows population NO emission factor histograms for
^
the six classes of gas turbine engines in which data on more than two
units were found. The graphs for the small turbine category show numbers
*Regenerative units use exhaust gases to preheat combustion air,
52
-------
TABLE 6-1. N0x EMISSION FACTORS SURVEY OF SIMPLE AND
REGENERATIVE CYCLE GAS ENGINES
Turbine
Size
Large
>15 MW
(>20,000 hp)
Med i urn
4 to 15 MW
(5,300 to
20,000 hp)
Small
<4 MW
(<5,300 hp)
Units
No. Engines h
ppm @ 15* 02
lb/MWHb
g/np-hrb
ng/Jc
lb/MBtuc
lb/MSCFC
or
lb/103 gal
No. Engines b
ppm 1? 15!t 02
lb/MWHb
g/hp-hrb
ng/Jc
Ib/MBtuC
lb/MSCFC
or
lb/103 gal
No. Engines b
ppm @ 15% 02
lb/MWHb
g/hp-hrb
ng/Jc
Ib/MBtuC
lb/MSCFC
or
lb/103 gal
Baseline NOX Emissions as a Function of Cycle and Fuel3
Simple Cycle
Natural Gas
4
98
4.1
1.4
140
0.32
350
8
80
3.8
1.3
120
0.29
300
30
78
4.9
1.7
120
0.28
300
Liquid Fuel
16
188
10. 2d
3.5^
360
0.85
120
3
108
6.1
2.1
210
0.48
70
58
93
5.6
1.9
180
0.41
47
Regenerative Cycle
Natural Gas
__
._
::
~
_.
i
__
6.2
2.1
180
0.42
440
Liquid Fuel
2
340
12.0
4.1
650
1.51
220
..
_.
-_
--
--
1
--
11.4
3.8
360
0.84
120
aNO values reported in terms of NO,
U X L.
Output specific values
clnput specific values
Average of 14 units only
53
-------
4
3
i
~ 5 i
= 4 _
1 3 _
_ /
5
^ 1
"H7 Average
/7/Y ^/
I//J//////////X//// Mfl !//] I///)
200 300 400 500 600 700
I I 1
.0.5) (1.0) (i.5)
NO emission factors. nq/J (Ib/MBtu)
a. Large, Simple Cycle, Liquid Fuel Fired
Average
I
m w, m
v i 1 | 1
50 100 150 200
(0.3) (0.4;
ng/J
Large, Simple Cycle, Natural Gas Fired
NO emission factors, ng/J (Ib/MBtu)
(o.i;
Average
2 -
1 -
_A __
//
m
i
m
A/ 1 i
50 100 150
VM
\
200
(0.2)
(0.3)
(0.4)
(0.5)
NO emission factors, ng/J (Ib/MBtu)
c. Medium, Simple Cycle, Natural Gas Fired
Figure 6-1.
Population histograms of NOX emission factors
for gas turbine engines.
54
-------
A
V/A
100 l'50
(0.25)
Average
!
WA W\
2"00 2*50 3do
(o.'so) (o1.
NO emission factors, ng/J (Ib/MBtu)
d. Medium, Simple Cycle, Liquid Fuel Fired
D
JO
Average
3 _
2 _
1
| 3
'w,wn//\ ui W/M* m
v ^o ido 1^0 2oo 25'o
1 1 1
(0.2) (0.2) (0.4) (.05)
NO emission factors, ng/J (Ib/'IBtu)
e. Small, Simple Cycle, Natural Gas Fired
Average
4
2 ~
l
V/A
f//t
7flt
y/<
6
9
1
^
77
00
//
15
3
₯/
200
(0.5)
^
f//
Y/t
^V/A W/A
r "«" |
300 400
(1.0)
NO emission factors, ng/J (lb/^1Btu)
f. Small, Simple Cycle, Liquid Fuel Fired
Figure 6-1. Concluded.
55
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in some of the boxed squares. These numbers represent averages of NO
A
emission values as they were presented in the literature; individual
values were not presented. The small liquid fuel fired turbine histogram
appears to be bimodal in appearance. This characteristic does not appear
to be related to turbine size or to fuel as all four fuels, Jet A.,
kerosene, and No. 1 and No. 2 fuel oils appear in both modes. It may be
related to the make of turbine or to the method of testing.
6.3 STATE-OF-THE-ART CONTROL TECHNIQUES FOR NOX EMISSIONS WATER
INJECTION
Water injection into the combustion zone in either as a liquid or
as steam has been used to increase efficiency since 1961 with NO
x
control being a fringe benefit. Not until 1971 was it primarily used to
meet NO regulations (Reference 6-1). A water/fuel ratio of 0.5
A
generally provides a NO reduction of 50 percent and for a water/fuel
A
ratio of 1.0, 80 percent. Steam appears to be less effective as the
energy for vaporization is no longer supplied by the combustion process of
the turbine. Figure 6-2 illustrates the effect of increasing the
water/fuel ratio in reducing the overall NO concentration. Steam/water
A
injection appears to work equally well for natural gas and distillate oils,
6.4 NITRIC OXIDE AS PERCENT CONSTITUTENT OF TOTAL NO EMISSIONS
A
Dietzman and Springer (Reference 6-2) have reported NO as a
percentage of NO for one turbine firing natural gas in the 4 to 15 MW
A
range. The average of the tests run was 87 percent. Nitric oxide (NO)
was not measured on any of the other turbines examined during this test
program. Dewerth (Reference 6-3) analyzed two 400 hp turbines at 60
percent load for both NO and NO and obtained an 86 percent average of
A
NO.
Previously, Tuttle, et al., (Reference 6-7) reviewed much of the
data prior to 1974 and found that it was clearly contradictory as to
whether N07 (and inversely NO) is a small or large fraction of total
NO emissions for gas turbine engines. Recently Johnson and Smith
A
(Reference 6-8) varied a 45 MW gas turbine from idle (15 MW) to full
load. NO as a percentage of NO increased from 0 to 78 percent as shown
A
in Figure 6-3. This is roughly collaborated by a second test run by
Wasser (Reference 6-4) on a 0.125 MW turbine at an EPA facility as shown
in Figure 6-4; however, results at low loads indicate a considerable
56
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3U
80
70
60
c
o
4->
£ 50
T5
QJ
i-
X
O
z
g 4°
u
i_
D-
30
20
10
0
D Natural gas ^"^ Q
O Liquid fuel / Ss
/ On
/ D ° 0
-6 °o°
/ o ^,
/ ^^*
/D o 0 ^x^
/ '
1 OQ /
- i <§) /
/o /
/ D /
/ .
; /
- 1 /
- If
-,'/
/ 1 1 1 1 1
f-
(«
v»
?i
<
0.2 0.4 0.6 0.8 1.0 1.2
Water/Fuel Ratio
Figure 6-2. Effectiveness of water/steam injection in
reducing NO emissions (Reference 5-1).
A
57
-------
120
100 -
80
s:
c_
c_
i 60 -
C
OJ
40 -
20 h
0
500
550
600
650
700
Turbine inlet temperature, C
38
Approximate load, MW
750
800
45
Figure 6-3.
NO and N02 concentrations at base of No. 3
stack for various turbine loads, i.e., turbi
inlet temperature (Reference 6-7).
ne
58
-------
c
o
c
8
o
220
200'
180
160
140
120
100
80
60
40
20
0
N
<;
I
20 40 60
80 100 120 140
Generator load, kW
160 180 200 220
Figure 6-4.
NO and NOX concentrations of a small turbine at various
loads firing No. 2 oil (Reference 6-4).
59
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quantity of NO in the EPA turbine exhaust and virtually none reported by
Johnson -and Smith. Also indicated is a dropoff of NCL directly from the
low load value for the EPA unit whereas the Johnson and Smith unit shows
an increase prior to dropping off. Much of this difference may be due to
the difference in fuels, type and size of the turbine and operating
parameters.
50
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REFERENCE FOR SECTION 6
6-1. Anon, "Standards Support and Environmental Impact Statement Volume I:
Proposed Standards of Performance for Stationary Gas Turbines,"
Emission Standards and Engineering Division, U.S. Environmental
Protection Agency, EPA-450/12-77-017a, September 1977.
6-2. Dietzmann, H. E., and K. J. Springer, "Exhaust Emissions from Piston
and Gas Turbine Engines Used in Natural Gas Transmission," Southwest
Research Institute, San Antonio, Texas. Prepared for American Gas
Association, Arlington, VA, January 1974.
6-3. Dewerth, D. W., "Air Pollutant Emissions from Spark-Ignition Natural
Gas Engines and Turbines," American Gas Association Laboratories,
Research Report No. 1491, September 1973.
6-4. Wasser, J. H., "Emission Characteristics of Small Gas Turbine
Engines: as reported in The Proceedings of the Stationary Source
Combustion Symposium, Vol. Ill, EPA-600/12-76-152, June 1976.
6-5. Crawford, A. R., et al., "Control of Utility Boiler and Gas Turbine
Pollutant Emissions by Combustion Modification -- Phase 1,"
EPA-600/7-78-036a, March 1978.
6-6. Acurex Corporation, Unpublished data.
6-7. Tuttle, J. H., et al., "Nitrogen Dioxide Formation in Gas Turbine
Engines: Measurements and Measurement Methods," Combustion Science
and Technology 9, 261 (1974)
6-8. Johnson, G. M. and M. Y. Smith, "Nitrogen Dioxide Emissions from a
Gas Turbine Power Station," International Clean Air Conference, The
Clean Air Society of Australia and New Zealand, Brisbane, Australia,
May 15-19, 1978.
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