DRAFT
SUMMARY OF RATIONALE TO
REGULATE NOx EMISSIONS FROM
STATIONARY RECIPROCATING INTERNAL
COMBUSTION ENGINES
Stanley B. Youngblood, George R. Often, Larry Cooper
Acurex Corporation
Energy & Environmental Division
485 Clyde Avenue
Mountain View, California 94042
March 1978
ACUREX REPORT TR-78-100
Prepared for
U.S. Environmental Protection Agency
Emission Standards and Engineering Division
Standards Development Branch
Research Triangle Park
North Carolina 27711
Contract 68-02-2611
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NOTICE
The attached document is a draft prepared by a Contractor. It
includes technical information and recommendations submitted by the
Contractor to the United States Environmental Protection Agency (EPA). It
is being distributed for review and comment only. The report is not an
official EPA publication and it has not been reviewed by the Agency.
The report, including the recommendations, will be undergoing
extensive review by EPA, Federal and State agencies, public interest
organizations, and other interested groups and persons during the coming
weeks. The report is subject to change in any and all respects.
The regulations to be published by EPA under Section 111 of the
Clean Air Act of 1970 will be based to a large extent on the report and the
comments received on it. However, EPA will also consider additional per-
tinent technical and economic information which is developed in the course
of review of this report by the public and within EPA. Upon completion of
the review process, and prior to final promulgation of regulations, an EPA
report will be issued setting forth EPA's conclusions concerning the sub-
ject industry and standards of performance for new stationary sources ap-
plicable to such industry judgements necessary to promulgation of regula-
tions under Section 111 of the Act, of cource, remain the responsibility of
EPA. Subject to these limitations, EPA is making this draft available in
order to encourage the widest possible participation of interested persons
in the decisionmaking process at the earliest possible time.
The report shall have standing in any EPA proceeding or court pro-
ceeding only to the extent that it represents the views of the Contractor
who studied the subject industry and prepared the information and re-
commendations. It cannot be cited, referenced, or represented in any re-
spect in any such proceedings as a statement of EPA's views regarding the
industry.
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TABLE OF CONTENTS
Section Page
1 SELECTION OF STATIONARY RECIPROCATING 1C ENGINES FOR
NEW SOURCES PERFORMANCE STANDARDS 1-1
2 SELECTION OF POLLUTANTS 2-1
2.1 NOx 2-1
2.2 HC and CO 2-1
2.3 Participate 2-2
2.4 SOx 2-3
3 SELECTION OF AFFECTED FACILITIES 3-1
3.1 Affected Diesel Engines 3-2
3.2 Affected Dual-Fuel Engines 3-10
3.3 Affected Gas Engines 3-14
4 BEST SYSTEMS OF EMISSION REDUCTION 4-1
5 SELECTION OF THE FORMAT OF THE PROPOSED STANDARD 5-1
5.1 Alternative Formats 5-1
5.1.1 Mass Per Unit Energy Output Basis 5-1
5.1.2 Concentration Basis 5-3
5.1.3 Fuel Basis 5-5
5.1.4 Equipment Standard 5-6
5.2 Proposed Format 5-7
6 SELECTION OF THE EMISSION LIMITS 6-1
REFERENCES FOR RATIONALE SUMMARY R-l
in
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SUMMARY OF RATIONALE TO REGULATE NO EMISSIONS FROM LARGE-BORE,
/\
STATIONARY RECIPROCATING INTERNAL COMBUSTION ENGINES
1. SELECTION OF STATIONARY RECIPROCATING 1C ENGINES FOR NEW SOURCE
PERFORMANCE STANDARDS
Previous investigators have concluded that stationary reciprocating
internal combustion engines are major contributors to nationwide emissions
^ ' ' '. In particular, these studies have shown that 1C engines are
significant contributors to total U.S. NO emissions from stationary
/\
sources. Figure 1^ ' shows that reciprocating 1C engines account for
16.4 percent of all stationary source NO emissions, exceeded only by
utility and packaged boilers.
An inventory of emissions from installed stationary reciprocating
engines was computed based on the information presented in summary form in
Table 1* . As a group, stationary reciprocating 1C engines (based on
1975 data) currently account for 3 to 9 percent of the NO , CO, and HC
X
emitted from all sources, and 9 to 14 percent of those emitted from sta-
tionary sources. This table also shows the percentage contribution to
nationwide totals from installed engines as a function of their size and
the type of fuel they consume. Table 2' ' shows the emission factors
used to generate Table 1. Annual production rates are estimated in Table
1 to indicate the potential number of sources that could be affected by
NSPS.
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Industrial Process Combustion 1.6%
Noncombustion 1.7%
Warm Air Furnaces 2.8%
Gas Turbines 3.0%
Fugitive 4.4%
Incineration 0.4%
Reciprocating
1C Engines
16.4%
Utility Boilers
49.0%
Packaged Boilers
20.7%
Figure 1. Distribution of stationary NOX emissions for the year 1974
(Reference 4).
1-2
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TABLE 1. NATIONWIDE EMISSIONS FROM INSTALLED 1C ENGINES
(Percent of Total Emitted in U.S. Each Year)a
Fuel
Diesel
Natural Gas
Dual-Fuel
Gasoline
hp Range
20 - 100
101 - 500
>500
Subtotal
<500
>500
Subtotal
<15
15-99
>100
Subtotal
Total
Annual
Production,
Unitsb
39,000
14,000
3,400
56,400
5,400
600
6,000
Included in Diesel
12,600,000e
85,000
10,000
12,600,000
+ 95,000
12,600,000
+ 157,400
Percent All Sources
Percent Stationary Sources
In Mass Units (106 metric tons/yr)
NOX
0.36
0.55
0.48
1.39
1.93
4.16
6.10
0.28
0.16
0.31
0.11
0.58
8.4
13.7
2.0
CO
0.029
0.45
0.016
0.09
0.107
0.229
0.336
0.02
1.84
0.81
0.31
2.96
3.4
11.0
3.6
HCT
0.062
0.095
0.033
0.19
0.81
1.73
2.54
0.11
0.56
0.29
0.10
0.95
3.8
8.8
0.9
aTotal U.S. emission from EPA Nationwide Air Pollutant Inventory for
1975(5)
bBased on estimates of average hp of engines used in each application
clncludes all engines in this size category (mobile and stationary).
Listed separately in the totals because of the unique nature of
this group.
1-3
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TABLE 2. EMISSION FACTORS FOR INVENTORY ON TABLE 1, g/hp-hr
(Reference 6)
Fuel
Gasoline >15
hp
<15 hp
Diesel >500
<500
hpb
hpc
Natural gas
Dual-Fuel
NOX
8.85
5.63
12.9
12.4
11.5
8.2
CO
102
295
1.8
4.47
2.81
2.0
HCT
8.38
20.5
0.43
2.12
4.86
3.1
aEmission factors for gasoline and diesel engines are modal
averages; those for natural gas and dual-fuel are for
rated conditions.
bBased on an average of rated condition levels from engines
considered
^Weighted average of two- and four-stroke engines. Weighting
factors = 2/3 for four-stroke and 1/3 for two-stroke
1-4
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Table 3*'' presents a clearer picture of the relationship between
the number of potentially controllable sources and their contributions to
the nationwide inventory from currently installed units-'. Table 3
shows that three-quarters of all NO emissions from installed stationary
A
1C engines are produced by a relatively small number of engines whose dis-
placement per cylinder is greater the 350 cubic inches. This table also
shows that numerous, small engines (nearly 13 million units of 1- to
100-hp) are the most significant contributors of HC and CO emissions.
(Note that nearly 80 percent of the HC emissions from engines smaller than
350 CID/cyl are methane, a noncriteria pollutant). Therefore, it can be
concluded that NO emissions are the most significant pollutant emitted
A
by stationary reciprocating engines, and most of these emissions are
emitted by large-bore (greater than 350 CID/cyl) engines.
Other studies have investigated the emissions of various stationary
sources to aid in establishing a priority for setting standards of perfor-
mance. For example, The Research Corporation of New England determined
the effect that standards of performance would have on nationwide emis-
sions of particulates, NOX, S02, HC, and CO from stationary
sources'8'. Sources were ranked according to the impact, in tons per
year of pollutant, that a standard promulgated in 1975 would have on
emissions in 1985. This ranking placed spark ignition reciprocating 1C
engines third and compression ignition 1C engines ninth on a list of 40
stationary NO emission sources.
A
i/Table 3 includes a separate row of emission estimates for engines
larger than 350-cubic-inch displacement per cylinder (CID/cyl). As is
shown in Section 3, it is more meaningful to discuss the applications and
emissions of large 1C engines on the basis of displacement per cylinder
rather than on horsepower.
1-5
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TABLE 3. EMISSIONS FROM 1C ENGINES BY SIZE AND ANNUAL PRODUCTION3
CTt
Size
>350 CID/cyl
>500 hp
>100 hp
>15 hp
All
Annual Production
Units/yr Increment NO
/\
c 1,600 4.83
4,000 2,400 4.92
28,000 24,000 5.59
152,000 124,000 6.26
12,752,000 12,600,000 6.42
Total (106 metric tons/year)
All Sources (10 6 metric tons/year)d
Stationary Sources (106 metric tons/year)d
Emissions from Install
(% U.S. Total
ed Enginesb
)
Increment CO Increment HCy
0.26
0.09 0.26 0
0.66 0.59 0
0.67 1.43 0
0.16 3.27 1
1.53 3.47
23.8 105.8
14.5 32.6
1.86
.003 1.87
.33 2.07
.83 2.42
.84 2.98
0.
24.
10.
Increment
0.01
0.20
0.35
0.56
72
2
4
aCompiled from Table 1
bExcludes emissions from natural gas engines under 500 hp (insignificant future impact projected from
new engines due to declining sales)
cCubic Inch Displacement per cylinder. All gas and dual-fuel engines >500 hp are taken to be greater
than 350 CID/cyl. Of the 3400 diesel units >500 hp, 1000 are assumed to be greater than 350 CID/cyl.
These large bore diesels contribute 80 percent of the emissions from diesel units >500 hp.
dFrom EPA Nationwide Air Pollutant Inventory for 1975(7).
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In a subsequent study, Argonne National Laboratory used the results
of the TRC study to develop a priority listing for setting NSPS.(9) In
developing this list, source screening factors were used to aid in estab-
lishing these control priorities. These factors considered:
Type, cost, and availability of control technology
Emission measurement methods and applicability
Enforceability of regulations
Source location and typical source size
Energy impact
Impact on scarce resources
t Other environmental media constraints
The study found that even with the application of maximum NSPS control
efforts, a significant increase of more than 40 percent in NO emissions
/\
occurs in the 1975 to 1990 period. Furthermore, the study concluded that
the control of reciprocating internal combustion engines is a matter of
high priority.
Other factors favoring the control of 1C engines are summarized
briefly below:
Control techniques for NO emissions have been shown to be
/\
effective and applicable to installed 1C engines. These tech-
niques can reduce NO emissions from 40 to 60 percent on the
A
average (see Section 4.0).
No Federal, State or local NO standards exist (with the ex-
/\
ception of Los Angeles and Chicago). Therefore, since engines
are manufactured for a variety of dispersed applications, a
single national standard is preferable.
1-7
-------
1C engines compete with gas turbines in certain applications.
Since NSPS are currently being developed for gas turbines, the
absence of standards for 1C engines may result in a shift away
from gas turbines to 1C engines. This could cause greater
NO emissions from both sources than if no standard were
A
applied to gas turbines, since 1C engines emit NO at greater
A
rates than gas turbines.
Furthermore, as shown in Section 3.0, sales of large-bore engines,
primarily for oil and gas exploration, have been substantial during the
past 5 years, and are anticipated to continue and possibly increase. Sta-
tionary reciprocating 1C engines, therefore, are significant contributors
to total nationwide emissions of NO Based on all these factors, then,
A
stationary reciprocating 1C engines have been selected for development of
standards of performance.
1-8
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2. SELECTION OF POLLUTANTS
2.1 NOX
Stationary reciprocating engines emit the following pollutants:
NO CO, HC, participates, and SO . As Table 3 indicates, the primary
* x
pollutant emitted by stationary reciprocating engines is NO , accounting
A
for over 6 percent (or 16 percent of all stationary sources) of the total
U.S. inventory of NO emissions. This table also illustrates that
A
large-bore engines emitted three-fourths of these NO emissions. It
A
will be shown in Section 4.0 that the control technology exists to effec-
tively reduce NO emissions from large-bore engines. Furthermore, NO
A A
emissions are projected to increase despite promulgation of all possible
New Source Performance Standards (NSPS). Therefore, NO emissions from
A
stationary reciprocating engines have been selected for control by means
of NSPS.
2.2 HC AND CO
Table 3 also showed that stationary reciprocating 1C engines emit
substantial quantities of HC and CO. However, the major 1C engine NO
A
emitters, large-bore engines, contribute relatively small amounts of the
total nationwide HC and CO emissions, especially if one considers that
more than 80 percent of the HC emissions from large-bore, spark ignition
engines are methane. Methane is not a criterion pollutant nor is it con-
sidered a pollutant at the levels which currently prevail in the atmo-
sphere^ '. Table 3 shows that numerous, small (1-to 100-hp) spark ig-
nition engines account for most uncontrolled HC and CO emissions. These
smaller engines, which are identical or similar to automotive engines,
2-1
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emit HC and CO at much higher rates than large-bore engines.?/. However,
as mentioned in Section 3.0, the large annual production of these smaller
engines makes enforcement of standards of performance for this group dif-
ficult. This and other factors discussed in Section 3.0 led to the recom-
mendation of NSPS for large-bore engines only. Standards of performance
for HC and CO emissions for large-bore engines will not be recommended
since:
The 1C engines which emit significant quantities of NO are
rt
low emitters of HC and CO
Many of the NO reduction techniques discussed in Section 4.4
}\
cause little or no increase in the already low HC and CO emis-
sions rates from large bore engines
Individual engines can cause violation of the National Ambient
Air Quality for HC, only under worst case atmospheric condi-
tions, and then only very close to the source (less than 0.3 km)
No controls for HC used in conjunction with NO controls have
/\
been demonstrated which reduce the already low nonmethane HC
emissions from large-bore engines
2.3 PARTICULATE
No standards of performance are recommended for either particulate
emissions or visible emissions (plume opacity). This recommendation stems
from the following considerations:
a Virtually no data are available on particulate emission rates
from stationary engines because it is so difficult, expensive,
2/
Large-bore engines are designed to run at steady-state conditions and
very efficiently. Consequently, cylinder temperatures are high and suf-
ficient oxygen is always provided to permit combustion to proceed toward
completion. Thus, emissions of HC and CO are small.
2-2
-------
and time-consuming to measure particulates, especially when
done in strict compliance with EPA Method 5 sampling techniques
It would be very expensive to enforce a standard on particu-
lates in compliance testing required measurements in accordance
with EPA Method 5
t It is believed that particulate emissions from stationary
engines are relatively unimportant because the plumes from most
of these engines are not now visible
2.4 SOX
The production of SO emissions are strictly dependent upon the
J\
intake rate of the sulfur contained in the fuel. Thus, the annual sulfur
emissions from an engine depends on the percent sulfur in the fuel and the
energy produced by the engine during that year. Since most engines burn
low-sulfur fuels and will continue to do so, standards of performance are
not recommended for sulfur emissions.
If users in urban or SO sensitive areas decide to buy new
^
engines and to use crude or residual oil as a fuel with these engines,
then the local air pollution authorities could impose fuel restrictions on
these engines. The cost of flue gas desulfurization for reciprocating 1C
engines is considered unreasonable. The use of low-sulfur fuels, however,
is economically feasible as a control of S02 emissions. Such fuel re-
strictions would be entirely independent of the standards of performance
from both a technological and enforcement viewpoint. That is, the absence
of federal emission limits on SO would not prevent a local air pollu-
^
tion control district from setting such a standard since the engine would
not have to be changed in order to meet the local standard.
2-3
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3. SELECTION OF AFFECTED FACILITIES
In sections 1.0 and 2.0 it was shown that NO emissions are the
/\
most significant pollutant emitted by stationary reciprocating 1C engines,
and that large-bore (>350 CID/cyl) engines account for over 75 percent of
all NO emissions from stationary engines. This section will establish
A
criteria that define which large diesel, dual-fuel, and natural gas en-
gines (referred to as "affected facilities") are to be affected by the
prop'osed standards of performance. The objective here is to apply stan-
dards of performance to significant sources of NO emissions.
x\
Thus, the following sections will present and explain the criteria
that define affected facilities after considering the applications served
by stationary engines, the number of units produced annually, and the
incremental NO contributed by the annual production. The following
/\
discussions are subdivided by the three operational fuel types: diesel,
dual-fuel, and natural gas. As will be discussed in the following para-
graphs, this classification separates large-bore engines into three rela-
tively distinct categories of engine applications. Initially, large-bore
engines will be defined as those exceeding 350 CID/cyl. Then, if neces-
sary, other criteria will be presented and explained to define affected
diesel, dual-fuel, and natural gas engines.
The following discussion summarizes an extensive study of the
applications of large-bore engines. Many of the conclusions presented
here are based on information concerning engine sales and applications
during the past 5 years. This information was voluntarily submitted by
engine manufacturers in response to Section 114 requests for information
^ '. This information cannot be cited for particular manufacturers
since it is considered proprietary by the manufacturers.
3-1
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3.1 AFFECTED DIESEL ENGINES
The primary high usage (large emissions impact), domestic applica-
tion of large-bore (i.e., >350 CID/cyl) diesel engines during the past 5
years has been for oil and gas exploration and production. These and
other applications are illustrated in Figure 2^ '. As this figure
shows, the market for prime (continuous) electric generation and other in-
dustrial applications all but disappeared after the 1973 oil embargo, but
was quickly replaced by sales of standby electric units for building ser-
vices, utilities, and nuclear power stations. The rapid growth in the oil
and gas production market occurred because diesel units are being used on
oil drilling rigs of various sizes. Sales of engines to export applica-
tions have also grown steadily since 1972, and are now a major segment of
the entire sales market.
Medium-bore (from 35 to 350 CID/cyl) as well as large-bore engines
are sold to oil and gas exploration, standby service, and other industrial
applications. Furthermore, manufacturers of medium- and large-bore
engines often compete for the same applications, although, in general,
medium-bore engines have a cost advantage (lower $/hp). This is because
the higher initial costs for a large-bore, heavy-duty, continuous-service
engine more than offset their lower maintenance and fuel costs. This
overlap in sizes is best illustrated in Figure 3 which shows a
considerable number of medium- and large-bore engines in the 500- to
2000-horsepower range. Figure 4 shows the displacement per cylinder that
corresponds to the ranges of horsepower offered by the manufacturers shown
in Figure 3. Table 4 shows the overlap for particular engine models.
The application with the greatest degree of overlap for mediumand
large-bore diesels is petroleum exploration. Smaller (250- to 1000-hp)
3-2
-------
i.ooo.ood
0)
I 500,000
0)
to
I.
O
OJ
I
CO
Data from:
Waukesha
Superior
GMC/EMD
Cooper
Colt
DeLaval
Total
diesel horsepower
Export
Total
domestic horsepower
4 IV Standby
III Oil and gas
production
I Electric generation
V Other
1972
1973
1974
Year
1975
1976
Figure 2. Sales of large-bore (>350 CID/cyl) diesel horsepower
(from References 12-17).
-------
CO
Medium-Bore
Ford
Hercules
Sterling [
Case
John Deere
Murphy
Allis-Chalmers
Cunmins
Caterpillar
Detroit Diesel
Waukesha
Large-Bore >350 CID/cyl
Superior
EMD (CMC)
Alco
Cooper-Bessemer
Colt
Delaval
>350 CID/cyl
10
100 1000
Horsepower
10000
Figure 3. Manufacturers of diesel engines categorized by horsepower.
-------
Med1 urn-Bore1
i
en
Ford
Hercules (white)
Case
John Deere
Allls-Chalmers
Detroit Diesel (CMC)
Sterling
Cummins
Murphy
Caterplller
Waukesha
Large-Bore
EMD (GMC)
Alco
Superior
Colt
Cooper-Bessemer
Delaval
I
J
100 1000
Cubic inch displacement per cylinder, CID/cyl
10000
Figure 4. Manufacturers of diesel engines categorized by cubic-inch displacement per cylirxler.
-------
TABLE 4. COMPARISON OF WAUKESHA, WHITE SUPERIOR, AND MEDIUM-BORE ENGINE MODELS GREATER
THAN 500 HORSEPOWER
CO
Manufacturer
Waukesha
Waukesha
Waukesha
Waukesha
Waukesha
Waukesha
Waukesha
Waukesha
Waukesha
Cumml ns
Caterpillar
Detroit Diesel
Superior
Division/Cooper
Model
VHP
VHP
VHP
VHP
VHP
VHP
VHP
VHP
VHP
VTA-1710-P
KTA
D398TA
D399TA
12V-149
16V-149
40-X-6
PT05-6
40-X-8
PTDS-8
Number of
Cylinders
6
6
6
6
12
12
12
12
16
12
12
12
16
12
16
6
8
Displacement
per Cylinder,
CID/CYL
482
482
482
556
482
482
482
556
556
143
192
245
245
149
149
687/596
687/596
Displacement,
cubic inches
2,896
2,896
2,896
3,335
5,792
5,792
5,792
6,670
8,894
1,710
2,300
2,945
3,927
1,788
2,384
4,120/3,575
5,493/4,767
Type
NA
TC
TC.AC
TC.AC
NA
TC
TC.AC
TC.AC
TC.AC
TC.AC
TC.AC
TC.AC
TC.AC
TC.AC
TC.AC
TC.AC
TC.AC
Continuous Rated
Horsepower
411
561
702
808
818
1,123
1,403
1,616
2,154
547
900
750
1,000
810
1,080
790/675
820/945
rpm
1,200
1,200
1,200
1,200
1,200
1,200
1,200
1,200
1,200
,800
,900
,200
,200
,800
,800
1,000
900
-------
medium-bore designs (e.g., Detroit Diesel, Cummins, and Caterpillar) are
used on portable drilling rigs to drill or service 2500- to 5000-foot
wells. These rigs are trailer-mounted or helicopter-transported; there-
fore, small, lightweight (approximately 4000-lb) engines are favored. In
addition, multiple units are preferred to insure some backup power in the
event one engine is down, ruling out a single unit of comparable total
horsepower.
Larger horsepower engines are used in groups of three to five to
provide 800 to 3000 hp for wells ranging in depth from 5000 to 25,000
feet. On most of these rigs, engines supply mechanical power to operate
the drilling (rotary table), mud pumps, and hoisting equipment. In the
larger units several engines from one manufacturer's engines operate pumps
or generator sets for auxiliary power^ '. A relatively new approach is
to generate AC power, rectify some of it for drilling power (variable load
DC motors), and use the rest to drive AC auxiliaries. This approach is
used primarily on offshore platforms, although there is interest in apply-
ing it to land-based sites despite its higher cost.
In conclusion, then, larger land-based drilling sites are the major
areas of overlap of service provided by both large-bore and medium-bore
manufacturers. These applications and baseload electric generation (to a
lesser extent, since horsepower sales are small) have the most significant
NO emissions impact because they are high usage (approximately 6000
^
hr/yr). However, a >350 CID/cyl definition of affected facilities would
result in some manufacturers (e.g., Waukesha) being subject to control
technology development costs, while medium-bore engines (of same power,
but more cylinders) serve identical applications would not incur these
costs. This is clearly undesirable since this criterion would unfairly
3-7
-------
place some large-bore engines in a less competitive position than similar
sized (by horsepower), smaller bore designs.
On the other hand, lowering the criterion to include medium-bore
engines serving the same applications as large-bore designs would increase
the number of affected facilities from about 200 to over 2000 units per
year (based on 1976 sales information). Considering this large number,
and the remoteness and mobility of petroleum applications, this alterna-
tive would create serious enforcement difficulties. Consequently, a cri-
terion is required that distinguishes numerous medium-bore, high-power
engines used for applications such as baseload electrical generation.
One possible criterion would be to define diesel engines that are
affected by NSPS as those exceeding 560 CID/cyl. This alternative would
exclude engines presently manufactured by Waukesha as well as those pro-
duced by Caterpillar, Detroit Diesel, and Cummins. This criterion, how-
ever, shifts the area of overlap in horsepower between regulated and
unregulated engines to other large-bore diesel manufacturers. This situa-
tion is depicted in Figure 5, which illustrates the relationship between
displacement per cylinder and rated (continuous) horsepower. All Waukesha
engines are excluded above the 560 CID/cyl limit. However, Superior's
diesel engines ranging in size from 596- to 825- CID/cyl would be subject
to standards. These engines compete in very few cases with Waukesha
diesel engines. Raising the limit to 700-CID/cyl would exclude Superior
engines in the 500- to 1000-hp range, but it would also exclude EMD and
Alco models, which compete with Colt (>700-CID/cyl, hence regulated) in
the 1000- to 3000-hp range. Establishing a 560-CID/cyl criterion, there-
fore, appears to be a viable method of excluding engines which
3-8
-------
10,000
A-19894
5,000
2,000
1,000 COLT
] SUPERIOR
cnpfrRTflD ฎ-
ritDPDTfiD Q^
500 WAUKESHA V p<
CATERPILLAR ป**
tuu LUPrliNo "*
DETROIT DIESEL
1
O^
^
Ol
O--
1 III
DELAVAL CM
O<
tafTt
^^7)
ฉ
COOPER <
COLT
fc O
fcrs
y^ Gem
CMC,
. 13.5
IM teฃ>
O- I
?ra1 Electric
-CO
'END
1 111
40
1,283
250
500 1,000 2,000
Horsepower (continuous rating)
5,000
10,000
Figure 5. Displacement per cylinder versus continuous rated horsepower
for diesel engines.
3-9
-------
compete with medium-bore designs without introducing a significant overlap
problem at a different power level.
After considering the sizes and displacements offered by each
diesel manufacturer and the applications served by diesel engines, a 560-
CID/cyl criterion was selected as a reasonable approach for separating
large-bore engines that compete with medium-bore engines from large-bore
engines that compete solely with each other. This cylinder displacement
size was chosen because engines below this size are generally used for
different applications than those above it. Therefore, it is recommended
that diesel engines greater than 560 CID/cyl be affected by standards of
performance.
3.2 AFFECTED DUAL-FUEL ENGINES
The concept of dual-fuel operation was developed to take advantage
of both compression ignition performance and inexpensive natural gas.
These engines have been used almost exclusively for prime electric genera-
Mq 22}
tion. Figure 6V " ' illustrates, however, that shortages of natural
gas and the 1973 oil embargo have combined to significantly reduce the
sales of these engines in recent years. The few large-bore units that
were sold (11 in 1976) were all greater the 350 CID/cyl. In fact, with
the exception of Superior Division/Cooper and Stewart-Stevenson (modified
Detroit Diesel engine) products, all were greater than 500 horsepower and
1000 CID/cyl as shown in Figures 7 and 8. Moreover, nearly all of the
dual-fuel engines sold since 1972 have been larger than 1000 hp. Only
Stewart-Stevenson manufactures dual-fuel engines less than 560 CID/cyl.
Sales of these units are less than 100 units per year and about 70 percent
of these are exported'^'.
3-10
-------
0)
Q.
-------
Medium-Bore
Stewart-Stevenson
Large-Bore
Superior
Cooper-Bessemer
Colt
Del aval
CO
I
fxj
10
100
1000
Horsepower
10000
Figure 7. Manufacturers of dual-fuel engines categorized by horsepower.
-------
Medium-Bore
Stewart-Stevenson | |
Large-Bore
Superior | |
Colt
Cooper-Bessemer
Del aval
CO
i
CO
100 1000 10000
Cubic inch displacement per cylinder, CID/cyl
Figure 8. Manufacturers of dual-fuel engines categorized by cubic-inch
displacement per cylinder.
-------
Although a >350 CID/cyl limit would subject nearly all new dual-
fuel sources to standards of performance (only engines manufactured by
Stewart-Stevenson would be excluded), it is recommended that thecriterion
chosen to define affected diesel engines (>560 CID/cyl) also be applied to
dual-fuel engines. The reason is that supplies of natural gas are likely
to become even more scarce, possibly causing recently installed or future
dual-fuel units to convert to diesel fuel operation. Any additional
diesel engines that would be created by conversion from dualfuel operation
should be subject to the same regulations applicable to other large diesel
engines.
3.3 AFFECTED GAS ENGINES
The primary application of large (>350 CID/cyl) gas engines during
the past 5 years has been for oil and gas production. The primary uses
are to power gas compressors for recovery, gathering, and distribution.
(24 29)
Figure 9V ~ ', based on manufacturer's data from response to the June
16, 1976 Section 114 requests for information, illustrates that 75 to 80
percent of all gas engine horsepower sold during the past 5 years was used
for these applications.
During this time sales to pipeline transmission applications
declined. Combined with standby power, electric generation, and other
services (industrial and sewage pumping), these other applications accoun-
ted for the remaining 20 to 25 percent of horsepower sales. The growth of
oil and gas production applications during this period corresponds to the
increasing efforts to find new, or recover marginal, gas reserves and dis-
tribute them to the existing pipeline transmission network.
3-14
-------
1,000,000'
CO
_i
en
J_
-------
Figure 10 illustrates the number of gas engines sold for five size
groups during the past 5 years. The large number of smaller than 500-hp
engines that were sold during this period are one or two cylinder engines
used on oil well beam pumps and for natural gas well recovery and gather-
ing. Most of the other, larger gas engines that were sold during this
period ranged from 500 to 2000 hp. In 1976, approximately 400 engines in
this size range were sold, primarily for oil and gas production (see
Figure 9). Most of these gas engines were manufactured by Caterpillar,
Cooper, Waukesha, and White Superior.
With the exception of standby service, all the applications of
Figure 9 are high usage (approximately 6000 hr/yr) and, therefore, contri-
bute significant NO emissions. It is estimated that the 400,000 gas-
A
engine horsepower sold for oil and gas production applications in 1976
caused 38,400 tons of NO emissions, or nearly three times more NO
A /\
than was caused by 200,000 diesel-horsepower (>350-CID/cyl) sold for the
same application in that year (see Section 3.1). Thus, large-bore gas
engines are primary contributors of NO emissions from new stationary 1C
A
engines. Therefore, standards of performance should be directed particu-
larly at these sources.
If affected engines were defined as those <350-CID/cyl, then all
manufacturers of gas engines greater than 500 hp, except Caterpillar,
would be affected by proposed standards of performance. However, large
Caterpillar gas engines range from 225 to 930 horsepower and, therefore,
compete with the other large-bore manufacturers (particularly Waukesha).
Figures 11 and 12 show more clearly the overlap in horsepower provided by
manufacturers of engines of various cylinder displacements. Therefore, a
3-16
-------
co
s~
O)
I
800
700
600
500
400
300
200
100
0
5. >4000 hp
Legend:
1
2
3
4
<500 hp
500-1000 hp
1000-2000 hp
2000-4000 hp
1972
1973 1974
Year
1975
Figure 10. Size distribution of gas engines sold during the past 5 years.
-------
Medium-Bore
to
00
Continental
Hercules (white)
Chrysler
Ford
Chevrolet (GMC)
Cooper-Ajax
Stewart-Stevenson
Caterpillar
Waukesha
Large-Bore
Superior
Colt
Ingersoll-Rand
Delaval
Cooper-Bessemer
->350 CID/cyTJ
10
100
1000
10000
Horsepower
Figure 11. Manufacturers of gasoline and natural gas engines categorized by horsepower.
-------
Medium-Bore
co
i
Continental
Chrysler
Chevrolet (GHC)
Ford
Hercules (white)
Stewart-Stevenson
Caterpillar
Waukesha
Cooper-Ajax
Large-Bo re
Superior
Colt
Del aval
Ingersoll-Rand
Cooper-Bessemer
I
n
100 1000
Cubic inch displacement per cylinder
10000
Figure 12. Manufacturers of gasoline and natural gas engines categorized by
cubic-inch displacement per cylinder.
-------
350-CID/cyl limit would give one manufacturer an unfair competitive advan-
tage over other large-bore engine manufacturers. Thus, although a 350-
CID/cyl limit would subject most significant gas engine sources of NO
A
emissions to potential standards of performance, this criterion should be
revised based on the following considerations:
The 350-CID/cyl criterion excludes the only other manufacturer
(Catepillar) of gas engines greater than 500 hp. Caterpillar
gas engines compete directly with the large gas engines manu-
factured by Cooper, Waukesha, and White Superior, which would
be regulated.
No emissions have been measured or control techniques demon-
strated for 1- and 2-cylinder engines which would be included
in potential standards of performance by the existing
350-CID/cyl limit.
The first observation suggests that the criterion should be low-
ered, or another definition adopted, to include the large Caterpillar
engines that compete in identical applications with Cooper, Waukesha, and
White Superior units. Although Caterpillar has not reported controlled
emissions data for their gas engines, control techniques have been demon-
strated on other similar gas engines and should be effective when applied
to Caterpillar engines, since they are all similar in design (i.e., car-
bureted and gas injected engines that are either turbocharged and after-
cooled or naturally aspirated).
Table 5 compares large Caterpillar gas engines with Waukesha models
that are greater than 350 CID/cyl. As this comparison illustrates,
Caterpillar engines with smaller displacements per cylinder and greater
numbers of cylinders serve about the same power range as do the larger
3-20
-------
TABLE 5. COMPARISON OF LARGE CATERPILLAR GAS ENGINES WITH
WAUKESHA GAS ENGINES >350 CID/CYL
MFG/Model
Caterpillar
G399
G398
G379
G353
G342
Waukesha
L7042
L5790
L5108
F3521
F2895
#CYL
16
12
8
6
6
12
12
12
6
6
CID/CYL
245
245
245
245
207
587
482
426
587
482
Continuous HP @ 1,200 rpm
600 to 930
450 to 700
300 to 450
225 to 350
200 to 295
888 to 1,359
726 to 1,114
645 to 987
432 to 674
360 to 558
3-21
-------
Waukesha engines. On the basis of this table, either of the following two
steps would subject Caterpillar gas engines to potential standards of per-
formance:
9 Select a criterion of >240-CID/cyl
Define affected gas engines as those >350-CID/cy1 or
>8-cy1inder and >240-CID/cy1
Both measures would essentially include only Caterpillar engines in
the same power range as Waukesha. The second definition has a slight ad-
vantage over the first since it includes only Caterpillar engines that
have Waukesha counterparts of about the same power (note that the 240-
CID/cyl criterion alone would include the Caterpillar 6353, which has no
large Waukesha counterpart). Therefore, the >350-CID/cy1 or >8-cy1inder
and >240-CID/cy1 definition of affected gas engines is recommended.
With regard to one and two cylinder engines, it is recommended that
they be excluded from potential standards of performance. This suggestion
can be supported considering:
At present these engines account for less than 10 percent of
all gas engine horsepower and, therefore, are less significant
N0x emitters than the larger gas engines used for oil and gas
production
These sources are numerous and widely dispersed in remote
locations
These engines are low rated-/ and therefore, probably have
lower NO emissions than the larger, higher rated gas engines
/\
5/
-Operate at a small fraction of their potential power output.
3-22
-------
In addition to these factors, consideration should be given to the
undeveloped control technology for these engines. A spokesman for one
manufacturer noted that they are only currently preparing to measure NO
/\
emissions from their one- and two-cylinder engines. Therefore, it is
recom- mended that all one- and two-cylinder gas engines be exempted from
potential standards of performance.
In summary, then, it is recommended that the following criteria
define gas engines that are to be affected by standards of performance:
Affected facilities are defined as engines that are either
>350-CID/cy1 or >8-cy1inder and 240-CID/cyl
All one or two cylinder gas engines are exempt from standards
of performance
3-23
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4. BEST SYSTEMS OF EMISSION REDUCTION
Four control techniques, or combinations of these techniques, have
been identified as demonstrated NO reduction systems for stationary
A
large-bore reciprocating internal combustion engines. These systems can be
used to meet any one of three alternative emission standards. These tech-
niques are: (1) retarded ignition or injection, (2) air-to-fuel ratio
changes, (3) manifold air cooling, and (4) derating power output (at con-
stant speed). In general these techniques are applied by changing an
engine operating adjustment, although manifold air cooling may require a
larger heat exchanger, and air-to-fuel changes may require resizing of a
turbocharger.
These techniques reduce NO emissions by lowering peak flame tern-
A
peratures. Some of the techniques may result in increased fuel consumption
and/or engine maintenance. In general, retard is the most effective NO
A
control technique for diesel-fueled engines, and air-to-fuel changes for
natural gas units. Both retard and air-to-fuel changes are effective in
reducing NO emissions from dual-fuel engines.
The choice of control, or combination of controls, selected for a
given engine to meet a standard of performance will be influenced by the
response of that engine type to the control. The most important considera-
tions are fuel economy and operating performance. Table 6 shows the cost
and effectiveness of the four control techniques that achieve NO reduc-
A
tions of 20, 40, and 60 percent for the major engine end uses. Average
cost penalties increase for larger NO reductions, but are less
4-1
-------
TABLE 6. COST PENALTIES FOR ALTERNATIVE NO EMISSION CONTROL TECHNIQUES
A
-p.
I
ro
Fuel/Application
Diesel/
Electric Generation
Dual Fuel/
Electric Generation
Natural Gas/
Oil & Gas
Transport
Natural Gas/
Oil and Gas
Production
Average NO Reduction
20% Reduction
Control
Technique
R, D, A,
RM, RMA
Excl. D
R, M, D,
A
Excl. D
R, M, D,
A
Excl. D
R, M, D,
A
Excl. D
Annuali zed Cost
Increase, %
Range Avg.
0-31 7
0-8 4
1-14 6
1-6 3
1-21 6
1-3 1
1-11 4
1-3 1
40% Reduction
Control
R, D, AM,
RA
Excl. D
R, M,
D, A, RM
Rxcl. D
R, D, A,
RMA
Excl. D
R, D, A,
RMA
Excl. D
Annual i zed Cost
Increase, %
Range
3-40
2-30
2-5
1-47
1-6
2-8
2-7
Avg.
13
4
7
4
9
3
4
4
60% Reduction
Control
Technique
R, RA
R, D,
RA
Excl. D
D, A,
RMA
Excl. D
D, A,
RMA
Excl. D
Annual i zed Cost
Increase, %
Range
14-18
5-33
5-6
2-36
2-6
2-11
2-7
Avg.
16
14
5
10
4
4
5
T-772
R - Retard; M - Manifold Air Cooling; A - Air-to-Fuel Charges; D - Derate
-------
than 6 percent if derate is excluded, with the exception of a 16-percent
average increase for diesel engines to achieve 60-percent reduction.
These techniques would most likely be implemented by manufacturers
of stationary engines. Engines would be sold with operating specifications
that would satisfy standards of performance. The owner would operate the
engine within these specifications to maintain the engine warranty and to
ensure proper performance.
Other techniques to reduce NO emissions exist but are not cur-
y\
rently considered demonstrated due to technical limitations, high costs,
and/or a lack of data. These techniques include exhaust gas recirculation
(EGR), combustion chamber modification (CCM), water induction, speed
changes, and catalytic reduction. Although EGR and CCM appear technically
feasible, data is limited, and they would require additional time (3 to 5
years) and expense to develop. Water induction has shown effective NO
A
reductions, but also causes serious operating and maintenance problems due
to deposits within the engine and fouling of lubricating oil. Speed
changes do not appear feasible for most existing and new facilities, and
virtually no data exists for catalytic reduction of NO from large-bore
/\
reciprocating engines.
Standards of performance based on the four demonstrated control
techniques would reduce national NO emissions by 75,000 to 220,000 tons
A
(metric) annually in the fifth year after the standard went into effect,
depending on the stringency of the standard. This estimate assumes con-
stant sales during this interval.
Standard of performance based on the best NO control techniques
/\
would cause no other significant environmental impacts such as increased
emissions of other pollutants (HC and CO), solid waste, water, or noise.
4-3
-------
In general, the data indicated that HC and CO emission levels are insensi-
tive to NO reductions. Dirty lubricating oil is essentially the only
A
solid waste from engines and this is presently recycled or burned as a sup-
plemental fuel. Water is used for engine cooling and is treated to prevent
scaling. Wastes from this treatment are routinely discarded according to
local regulatory requirements. In general, stationary engines are remotely
located, or isolated, minimizing noise exposure hazards and annoyance.
The potential energy impact of standards of performance are esti-
mated to be 420,000 barrels of oil and 780 million cubic feet of gas in the
fifth year after standards go into effect, assuming a 10-percent fuel con-
sumption penalty. This impact is less than 0.04 percent of 1972 crude oil
and natural gas consumption.
Standards of performance based on the most stringent alternative
would increase total capital investments by $5 million over 2 years. Total
annualized costs are projected to increase $45 million in the fifth year
after promulgation. The total U.S. electric bill would increase 0.3 per-
cent after full phase in 30 years of the standard. Delivered natural gas
prices would increase 0.4 percent. Oil imports are projected to increase
0.6 percent after the fifth year of standards, based on 1976 oil imports
(2,850 million barrels). No impact on national employment is anticipated.
Based on these considerations, therefore, standards of performance
will be recommended based on four alternative control techniques:
(1) retard; (2) air-to-fuel changes; (3) manifold air cooling; and (4)
derate. It is also possible that some combination of these techniques will
be used to meet a proposed standard of performance.
4-4
-------
5. SELECTION OF THE FORMAT OF THE PROPOSED STANDARD
The format of a standard is the units in which the emission limits
are expressed. Four potential formats were considered and the advantages
and disadvantages of each are discussed below. The four possibilities are:
Mass per unit energy output (g/hp-hr)
t Concentration (ppm)
Input fuel (kg/kcal)
Equipment standard
5.1 ALTERNATIVE FORMATS
5.1.1 Mass Per Unit Energy Output Basis
A standard which limits emissions on the basis of mass per unit
energy output is really one which relates emissions to unit productivity
because the product of an engine is its energy generation. The advantages
and disadvantages of such a format are as follows:
Pros: (a) The emission restrictions are directly related to energy out-
put, that is, such a standard relates the environmental impact
of the source to the service it provides.
(b) The manufacturers believe strongly that the emission charac-
teristics of engines should be expressed in terms of mass per
energy output. Thus, all of the existing data are in this
format.
Cons: (a) It is harder to measure emissions in terms of mass per unit
energy output because one needs to measure not only the emis-
sion rate but also the power output. In the laboratory power
is usually measured on an engine dynamometer, but this device
cannot be used on engines which are installed in the field.
However, three solutions have been proposed to overcome
5-1
-------
these difficluties and still enable development of a standard
based on mass per unit energy output.
(i) Measure fuel flowrate and use the fuel flowrate versus
power output curve that was generated by the engine
manufacturer during the production run-in tests as a
means of determining the engine power during an emis-
sion test in the field. It has been estimated that
such an approach would yield an answer which is accu-
rate to within 10 percent.
(ii) Infer the power output of the engine from the power
output of the device that is driven by the engine. For
example, if the engine is used to turn an electric gen-
erator, the power output of the generator can be mea-
sured quite easily and the power input to the generator
inferred assuming some coupling efficiency. The usual
practice in the industry is to assume that the engine
power output is 5 percent greater than the generator
output^ '. This approach is deemed to be accurate
to within 5 percent.
In the case of engine driven compressors, two meth-
ods are available for estimating the energy transferred
by the compressor to the gas which it is compressing.
These are called the MIT and the Beta methods, and they
are similar in concept, differing only in degree of
Hi}
automationv;. They are applicable to reciprocating
compressors, and are based on the recognition that the
energy input to the gas is equal to the area under a
5-2
-------
curve of gas pressure versus instantaneous compressor
cylinder volume. The auto- mated approach computes the
area under the measured pressure versus volume curve.
Correction factors are then applied for energy losses
in the compressor itself and between the engine and
compressor. Industry sources claim that these
techniques, which are commonly used within the
industry, are accurate to within 10 percent^ '.
(iii) A torsion meter can be installed between the engine and
the unit which it is driving. Engine torque and speed
are used to determine power. These devices are avail-
able for use on large-bore engines and turbines. They
are considered to be accurate to within 1 percent, but
as might be expected, they are considerably more expen-
sive than either of the first two alternatives. Units
are available which cost between $5000 and $15,000.
They do have the advantage of being more general in
that they can be used for applications other than elec-
(33^
trical generation and pumpingv '.
Since these three approaches are available to determine power out-
put in the field, the major drawback of a mass per unit energy output
standard can be overcome.
5.1.2 Concentration Basis
A standard that is based on concentration units would regulate an
engine by setting a limit on the number of NOV molecules per million
A
exhaust molecules that could be emitted by an engine. Such a standard
5-3
-------
would be expressed in terms of parts per million (ppm). In order to pre-
vent a user from attempting to reduce the concentration of the pollutants
in the exhaust stack by adding air to dilute them, such a standard would
require the user to correct the results of his emission tests to a speci-
fied level of oxygen content in the exhaust. Since large-bore recipro-
cating internal combustion engines usually operate lean, a value of
15-percent excess oxygen would be an appropriate specified content. The
advantages and disadvantages of this format are discussed below.
Pros: (a) It is easier to regulate a standard which is based on concen-
tration units because emission measurement instrumentation
provide such results directly.
Cons: (a) Such a format does not show, directly, the relationship be-
tween the environmental impact from the source on a use basis.
That is, engine horsepower and use directly control the total
quantities of NO emitted to the atmosphere each year. On
A
the other hand, concentration at the source may be largely
independent of the environmental impact.
(b) A standard based on concentration may discourage manufacturers
from improving the fuel economy of their engines. In theory a
manufacturer could reduce an engine's ppm without affecting
its brake specific N0x (g/hp-hr) by simply readjusting it to
a poorer fuel rate. In practice, of course, he would probably
not follow such an approach. Moreover, controls which
increase fuel consumption frequently reduce specific emissions
anyway. Nevertheless, a concentration standard could
discourage attempts to reduce emissions and fuel consumption
simultaneously.
5-4
-------
5.1.3 Fuel Basis
For this format the emission limit would be specified in terms of
kilograms N0ฅ per kilocalorie fuel input (equivalent to Ib NO /MBtu).
A X
Standards of performance for new utility boilers are expressed in these
terms. The advantages and disadvantages of proposing standards for new
stationary reciprocating engines in terms of fuel input are discussed
below.-'
Pros: (a) A standard that is based on fuel input is easier to enforce
than one which is based on power output because it does not
require the power measurement. Fuel input is normally mea-
sured by an engine operator.
Cons: (a) It is more complicated to relate emissions to fuel input than
it is to merely express them in concentration units as mea-
sured by the instruments. The additional complexity arises
because it is necessary to calculate the total exhaust flow-
rates in order to compute the total mass emissions of the
pollutants.
(b) A standard which is based on fuel input could penalize the ef-
ficient engine. That is, for two engines with the same brake
specific emissions, the more efficient engine (which consumes
less fuel) will have a higher fuel based emissions level.
-No standards are proposed for SOX emissions. However, if they were,
it would be appropriate to express them on a fuel basis since the
only rational method of complying with such a standard is to limit the
sulfur content of the fuel. The production of N0x, however, is related
to both fuel bound nitrogen and NOX produced during combustion with the
atmosphere.
5-5
-------
5.1.4 Equipment Standard
An equipment standard is one which specifies equipment which the
user must install to comply with the standard. For example, an equipment
standard for an 1C engine could state that the user must install a cataly-
tic muffler on his engine, or that he must cool the inlet air to a certain
temperature. The advantages and disadvantages of such a format are
discussed below.
Pros: (a) A standard that is written in terms of equipment can be easier
to enforce than any other standard because it usually does not
rely on exhaust emission measurements. In most cases an in-
spector merely needs to verify that the equipment is being
operated in accordance with the instructions provided by the
manufacturer.
Cons: (a) An equipment standard that specified such likely control para-
meters as ignition timing, air-to-fuel ratio, manifold inlet
temperature, percent EGR rate, or chamber geometry would be
inappropriate or difficult to enforce. It would not be effec-
tive because these parameters are different for each engine.
Moreover, emissions from an engine depend not only on the type
of combustion system used but also on the details of the shape
and size of the combustion chamber.
(b) It is contrary to EPA philosophy to specify design practices
that must be followed in order to meet emission goals, because
such an approach interferes with the operation of the free
market. A more acceptable approach is to set standards on the
basis of emission limits and then let the manufacturers
5-6
-------
develop engines which comply with these limits, using whatever
technologies they deem most appropriate.
5.2 PROPOSED FORMAT
Based on the arguments presented above, it is proposed that stan-
dards of performance for new reciprocating stationary engines be expressed
in terms of mass per unit energy output, that is, in terms of g/hp-hr.
The use of such a format causes the standard to relate the emission limits
directly to the product of the source category. The most significant fac-
tors in support of this conclusion are as follows:
t All the available emission data on the effectiveness of NO
/\
control technologies are presented in g/hp-hr
Adequate means are available to measure the power output of
stationary engines in field installations
A standard which is based on productivity does not indirectly
penalize an efficient engine
It is also proposed that the standard require the owner or operator
of a new engine to maintain it in accordance with the manufacturers
instructions for complying with the standard.
5-7
-------
6. SELECTION OF THE EMISSION LIMITS
The objective of standards of performance is to achieve reductions
in NO emissions from new, modified, or reconstructed stationary reci-
^
procating engines. Since uncontrolled NO emission levels from engines
A
vary among both engines of the same fuel type and of different fuels (even
after considering ambient conditions and measurement methods), a procedure
is required for setting standards of performance that will reduce average
uncontrolled emissions from new sources. Therefore, the following ap-
proach was used to establish the numerical emission limit for standards of
performance:
1. Establish average uncontrolled NO emissions for each fuel
type by applying a sales-weighting factor to the average emis-
sion level for a particular manufacturer's data
2. Determine alternative levels for the standard by applying per-
centage NO reductions (based on the effectiveness of demon-
A
strated control techniques) to the sales-weighted uncontrolled
emissions average for all engines of a given fuel type
3. Recommend an emission level(s) for standards of performance
after considering both the effectiveness and costs of the de-
monstrated techniques
Uncontrolled NO emissions from large stationary reciprocating
A
engines were presented in Chapter 4, section 3 of the draft Standards
Support and Environmental Impact Statement (SSEIS). These data indicated
that sales-weighted average uncontrolled NO emissions were: (1) 15
A
g /hp-hr for natural gas engines; (2) 8 g/hp-hr for dual-fuel engines; and
(3) 11 g/hp-hr for diesel engines.
6-1
-------
As was discussed in Section 4, the demonstrated NO control tech-
/\
niques include retarded spark ignition or fuel injection, manifold air
cooling, air-to-fuel changes, derate, and combinations of these tech-
niques. These techniques have demonstrated maximum NOX reductions rang-
ing from 65 to 90 percent of uncontrolled levels. Further, it was deter-
mined that discrete ranges of cost and energy impacts could be associated
with intermediate levels of control. Consequently, alternative standards
of performance were established for each fuel type based on 20, 40, and 60
percent average NO reductions.
/\
A detailed analysis was performed to determine the economic impacts
related to each alternative. This analysis established that the economic
impacts related to the alternatives are reasonable.
Based on this analysis and the effectiveness of demonstrated tech-
niques, 6 g/hp-hr was selected as the numerical emission limit for large
stationary reciprocating internal combustion engines. This level reflects
60-percent reduction of average NO emissions for natural gas engines
A
and 50-percent reduction for diesel engines. Although the available data
indicate that diesel engines could be controlled to a level that repre-
sents a 60-percent reduction from the uncontrolled sales-weighted average
(5 g/hphr), to date no manufacturer has tried the combination of controls
and/or degree of a demonstrated control required to reach this level.
Therefore, recognizing that: (1) some uncertainty exists in the data
base; and (2) no controlled emissions data were reported below 5 g/hp-hr,
the 6 g/hp-hr level is also recommended for diesel engines.
The standard for diesel engines is also applied to dual-fuel
engines since: (1) dual-fuel engines serve the same applications as
diesel engines; and (2) it is possible that dual-fuel units will switch to
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100 percent diesel operation as natural gas curtailments increase. Sales
of dual-fuel engines have ranges from 17 to 95 units annually over the
past 5 years, with a general trend of decreasing sales. Therefore, rela-
tively few sources will be affected by this provision.
Ambient atmospheric conditions of humidity and temperature can
significantly affect N0x emission levels. Therefore, ambient correction
factors are recommended to correct data measured at nonstandard humidity
and temperature to standard conditions. Standard conditions are defined
as: (1) 75 grains of moisture per pound of dry air; and (2) 85ฐF
ambient temperature. (These are the reference conditions cited for the
Revised Heavy Duty Engine Regulations for mobile vehicles for 1979 and
later years in the Federal Register, Volume 41, Number 101). Correction
factors were selected for both spark ignition (natural gas) and compres-
sion ignition (diesel/dual-fuel) engines. These factors are presented in
Table 4-2 of Chapter 4, Section 2 of the draft SSEIS. Consequently, these
ambient correction factors, as presented in the regulation, are to be used
to correct NO emissions measured during any compliance test for com-
A
parison with the numerical emission limits.
As an alternative, engine manufacturers, owners, or operators may
elect to develop their own ambient correction factors, since the recommen-
ded factors may not be applicable for certain engine models. All such
factors, however, must be substantiated with data and then approved by EPA
before they can be used to determine compliance with the NO emission
A
limit.
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A 15-month delay is recommended for the standard to take effect.
This delay will enable the manufacturers and owners to adapt NO con-
/\
trols to the remaining models in their lines (those not yet tested) and to
verify the durability of their engines with these controls. This period
of delay will commence with the proposal of standards of performance for
new stationary reciprocating internal combustion engines.
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REFERENCES FOR RATIONALE SUMMARY
(1) Bartok, W., et al. Systems Study of Nitrogen Oxide Control Methods for
Stationary Sources, Final Report. Volume II. National Air Pollution
Control Administration. NTIS Report No. PB-192-789. 1969.
(2) McGowin, C.R. Stationary Internal Combustion Engines in the United
States. Environmental Protection Agency. EPA-R2-73-210. April 1973.
(3) Brown, R.A., H.B. Mason, and R.J. Schreiber. Systems Analysis
Requirements for Nitrogen Oxide Control of Stationary Sources.
Environmental Protection Agency. EPA-650/2-74-091. June 1974.
(4) Preliminary Environmental Assessment of the Application of Combustion
Modification Technology to Control Pollutant Emissions from Major
Stationary Combustion Sources. Volume II-Technical Result. Acurex
Corporation. Report TR-77-28. pp. 5-46. February 1977.
(5) Computer printout of Nationwide Emissions Report, National Emissions
Data System, as of January 10, 1975. Obtained from the Monitoring and
Data Analysis Division, OAQPS, U.S. Environmental Agency.
(6) Youngblood, S.B. and G.R. Offen. Acurex interoffice Memorandum.
Emissions Inventory of Currently Installed Stationary Reciprocating
Engines. September 23, 1975.
(7) Op. Cit., Reference 5.
(8) Hopper, T.6. and W.A. Marrone. Impact of New Source Performance
Standards on 1985 National Emissions from Stationary Sources. The
Research Corporation of New England. October 24, 1975.
(9) Habegger, L.J., et al. Priorities and Procedures for Development of
Standards of Performance for New Stationary Sources of Atmospheric
Emissions. Argonne National Laboratory. May 1976.
(10) Air Quality Criteria for Hydrocarbons. National Air Pollution
Control Administration. AP-64. Washington, D.C. 1970.
(11) Goodwin, D.R., EPA/Emission Standards and Engineering Division.
Request for Information. June 16, 1976.
(12) Snyder, W.E. (Waukesha) and D.R. Goodwin (EPA). Private
Communication. July 20, 1976.
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(13) Thompson, M.P- (Superior) and D.R. Goodwin (EPA). Private
Communication. August 3, 1976.
(14) Hanley, G.P. (GMC) and D.R. Goodwin (EPA). Private Communication.
September 7, 1976.
(15) Greiner, S.D. (Cooper) and D.R. Goodwin (EPA). Private
Communication. August 4, 1976.
(16) Newton, C.L. (Colt) and D.R. Goodwin (EPA). Private Communication.
August 2, 1976.
(17) Fleischer, A.R. (DeLaval) and D.R. Goodwin (EPA). Private
Communication. July 30, 1976.
(18) Alberte, Tony. Portable Rigs Have Full Power Complement. Diesel and
Gas Turbine Progress. May 1976.
(19) Op. Cit., Reference 16.
(20) Op. Cit., Reference 15.
(21) Op. Cit., Reference 17.
(22) Op. Cit., Reference 13.
(23) Offen, G.R. (Acurex) and M. Andrews (Stewart Stevenson).
Interoffice Memorandum. December 6, 1974.
(24) Op. Cit., Reference 16.
(25) Op. Cit., Reference 15.
(26) Op. Cit., Reference 17.
(27) Sheppard, R.W. (Ingersoll-Rand) and D.R. Goodwin (EPA). Private
Communication. July 28, 1976.
(28) Op. Cit., Reference 12.
(29) Op. Cit., Reference 13.
(30) Offen, G.R. (Acurex) and Beightol, K. (Cooper-Bessemer). Telephone
Conversation. January 10, 1975.
(31) Ibid.
(32) Dietzmann, H.E. and K.J. Springer. Exhaust Emissions from Piston and
Gas Turbine Engines in Natural Gas Transmission. Southwest Research
Institite. AR-923. January 1974.
(33) Youngblood, S.B. (Acurex). Interoffice Memorandum: Availability of
Torsion Meters for Large Engines. February 7, 1975.
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