United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/S7-86/001 Apr. 1986
SERA Project Summary
Environmental Assessment of
NOx Control on a
Compression-Ignition, Large-
Bore, Reciprocating
Internal-Combustion Engine
C. Castaldini
The report gives emission results
from field testing of the exhaust gas
from a large-bore, compression-
ignition reciprocating engine burning
diesel fuel. An objective of the tests was
to evaluate the operating efficiency of
the engine with combustion
modification NOx control to reduce
emissions to below the proposed NOx
new source performance standard
(NSPS) of 600 ppm at 15 percent 02
dry- Engine NOx emissions were
reduced 31 percent (from 825 to 571
ppm) at 15 percent O2 with 3.5° of fuel
injection timing retard. This reduction
was accompanied by a 1 percent loss in
engine efficiency. CO emissions
decreased slightly (from 119 to 90
ppm). Total unburned hydrocarbons
remained relatively unchanged (25
ppm), as did particulate emissions (35
ng/J) and total organic emissions (55
ng/J). Volatile organics (boiling point <
about 100° C) accounted for the largest
fraction of the total organic.
Naphthalene, fIuoroanthene,
phenanthrene/anthracene, and pyrene
were the only organic priority pollutants
detected in both tests at levels below 70
micrograms/dscm.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research
Triangle Park, NC, to announce key
findings of the research project that is
fully documented in two separate
volumes of the same title (see Project
Report ordering information at back).
Introduction
This report describes emission results
obtained from field testing of the exhaust
gas from a large-bore, dual-fuel,
compression-ignition, reciprocating
internal-combustion (1C) engine burning
distillate oil (diesel fuel). Objectives of the
tests were to measure exhaust gas
emissions and to evaluate the operating
efficiency of the engine under baseline or
normal operating conditions and with
combustion modification NOx control to
reduce emissions to below the proposed
NOx New Source Performance Standard
(NSPS) of 600 ppm at 15 percent 02.
Emission measurements included
continuous monitoring of exhaust gas
emissions; source assessment sampling
system (SASS) sampling of the exhaust
gas with subsequent laboratory analysis
of samples to give total exhaust gas
organics in two boiling point ranges,
compound category information within
these ranges, specific quantitation of the
semivolatile organic priority pollutants,
and exhaust gas concentrations of 73
trace elements; Method 5 sampling for
particulate; Method 8 sampling for S02
and S03; and grab sampling of fuel and
engine lubricating oil for inorganic
composition determinations.
Engine NOx emissions were reduced
31 percent (from 825 to 571 ppm) at 15
percent 02 with the control approach
tested (3.5° of fuel injection timing
retard). This reduction was accompanied
by a 1 percent loss in engine efficiency
(from 36.3 to 35.3 percent). CO emissions
-------
decreased slightly (from 119 to 90 ppm) at
15 percent 02 under controlled operation.
Total unburned hydrocarbon emissions
remained relatively unchanged (at about
25 ppm, as propane) at 15 percent O2, as
did particulate emissions at about 35
ng/J heat input. Total organic emissions
also remained relatively unchanged at
about 55 ng/J. Volatile organics (boiling
point less than about 100°C) accounted
for the largest fraction of the total
organic.
Of the 58 semivolatile organic priority
pollutants analyzed, only naphthalene,
fluoroanthene, phenanthrene/anthra-
cene, and pyrene were detected in the
uncontrolled engine exhaust at levels of 7
to 70 jug/dscm. Levels of these in the
controlled engine exhaust were lower,
being less than 1 to 50 //g/dscm.
Summary and Conclusions
Test Engine
The test engine was a turbocharged
1,565 kW (2,100-Bhp), two-stroke,
opposed-piston, compression-ignition
Model 38TDD8-1/8 engine manufactur-
ed by the Fairbanks Morse Engine
Division of Colt Industries. Figure 1, a
schematic of the engine, shows the
turboblower arrangement of the inlet
combustion air and the opposed-piston
design. The combustion air is drawn into
the turbocharger where it is compressed
and discharged through an air cooler to
the positive-displacement lobe-type
blower. The blower, driven by the upper
engine crankshaft, discharges the air
directly to the cylinders through the
engine intake manifold. The air/fuel
mixture is compressed between the two
pistons which work vertically toward
each other in each cylinder. The upper
and lower pistons drive separate
crankshafts interconnected by a vertical
drive. Hot exhaust gas leading from the
lower cylinder ports drives the turbine of
the turbocharger assembly. The fuel is
ignited by the heat of compression.
Engine Operation and
Test Arrangements
The test program called for the analysis
of exhaust gas samples collected (1)
during uncontrolled or baseline
operation, and (2) with fuel injection
retard to lower NOxemissionsto or below
the level of the proposed NSPS. Table 1
summarizes the engine specifications,
operating parameters, and atmospheric
conditions during both tests.
For the baseline test, fuel injection
timing was set at the normal setting for
this engine, 16° before minimum volume
(RMV). Combustion modification NOx
control consisted of retarding the fuel
injection timing from 16 to 10.5° BMV.
The effect of 5.5° retard on the operation
of the engine was a loss in efficiency of
about 1.0 percent. This efficiency loss is
clearly identifiable by the increase in fuel
flow required to maintain rated power
output, the air flow was also increased
during the low-NOx tests as indicated by
the increase in blower discharge
pressure. However, the fuel/air ratio
during the low-NOx test decreased about
8 percent from the baseline level. Blower
discharge and engine exhaust gas
temperatures remained nearly constant
while there was a small reduction in
temperature at the turbine outlet of the
turbocharger.
Emission Measurements and
Results
The sampling and analysis procedures
used in this test program conformed to a
modified EPA level 1 protocol. Except for
continuous monitoring to exhaust gas
emissions, all exhaust gases were
measured at the exit of the engine muffler
into the uninsulated exhaust stack.
Emission measurements included:
• Continuous monitoring for NOx,NO,
CO, CO2, 02, and TUHC
• Source Assessment Sampling
System (SASS) for trace elements
and organic emissions
• EPA Method 5 for solid and
condensible particulate mass
emissions
• EPA Method 8 for S02 and SO3
emissions
• Grab sample for onsite analysis of
C, to C6 hydrocarbons by gas
chromatography (GC)
• Bosch smoke spot
In addition, samples of the engine
lubricating oil and the diesel fuel oil were
collected for analysis.
The analysis protocol included:
• Analyzing the fuel/lube oil, and
SASS train samples for 73 trace
elements using spark source mass
spectrometry (SSMS), supplement-
Blower
(second stage
in series)
Upper
Crankshaft
Compressor
(first stage)
Figure 1.
Exhaust
Outlet
Schematic of turboblower arrangement (courtesy of Fairbanks Morse Division of
Colt Industries).
-------
ed by atomic absorption
spectrometry (AAS)
• Analyzing SASS train samples for
total organic content in two boiling
point ranges: 100to 300°Cbytotal
chromatographable organics (TCO)
analysis and >300°C by gravimetry
(GRAV)
• Analyzing the SASS train samples
for 58 semivolatile organic species
including many POM compounds
• Performing infrared (IR) spectro-
metry analysis of organic sample
extracts
• Performing liquid chromatography
(LC) separation of selected sample
extracts with subsequent TCO,
GRAV, and IR analysis of LC
fractions
• Performing direct insertion probe
and batch inlet low resolution mass
spectrometry (LRMS) of selected
sample extracts
Bioassay tests were also performed on
the SASS organic sorbent module extract
to estimate this sample's potential
toxicity and mutagenicity.
Table 2 summarizes exhaust gas
emissions measured in the test program.
Emissions are presented as ng/J heat
input and as mg/dscm of exhaust.
As noted in Table 2, NOx emissions
were reduced with fuel injection retard to
1,040 ng/J from a baseline of 1,490
ng/J. CO emissions were also decreased
slightly. TUHC, paniculate, and total
semivolatile organic emissions were
relatively unchanged; nonvolatile organic
emissions increased with low-NOx
operation.
As a measure of the potential
significance of the emissions levels for
further monitoring evaluation. Table 2
also lists occupational exposure
guidelines for most pollutants noted in
the table. The guidelines listed are
generally either time-weighted-average
Threshold Limit Values (TLV) established
by the American Conference of
Governmental Industrial Hygienists, or
the 8-hr time-weighted-averaged
exposure limits established by the
Occupational Safety and Health
Administration. These are noted only to
aid in ranking the emissions for
evaluation. In this respect, pollutants
emitted at levels several orders of
magnitude higher than their guideline
might warrant further consideration,
while species emitted at levels
significantly lower than their guideline
might be considered of lesser concern.
Only elements emitted at levels
Table 1. Compression Ignition Engine Design and Operating Parameters
Engine Design Parameters Specifications
Model designation
Engine configuration
Bore/stroke, m (in.)
Number of cylinders
Displacement/cylinder, m3 (in.3)
Compression ratio
BMEP. MPa tpsia)
kW/cylinder (Bhp/cylinder) rpm
Injection timing
Lubricating oil
Lubricating oil consumption, ml/s (gph)
Fuel oil
Hours since last overhaul
Engine Operating Parameters
RPM (percent rating)
kW, (Bhp) (percent rating)
Generator output, kWe (percent rating)
Fuel flow, g/s(lb/hr)
BSFC. g/kW-hr(lb/Bhp-hr)
Fuel rate, k W, in/k Wt out (Btu/Bhp-hr)
Injection timing
Cylinder firing pressure, MPa (psig)
Compressor inlet air temp., K (°F)
Compressor outlet air temp., K (°F)
Blower suction temp.. K (°F)
Blower discharge temp., K (°F)
Blower discharge pressure, kPa (psig)
Air flow, kq/s (Ib/min)
Fuel/air ratio
Combined cylinder exhaust temp.,
K(°F)
Turbine exhaust temp., K (°F)
Engine efficiency, percent
Average Ambient Atmospheric Condition
Ambient temperature—dry bulb, K (°F)
Barometric pressure, kPa (in. Hg)
Relative humidity, percent
38TDD8-1/8
2-stroke, opposed-piston
0.206/0.254 (8-1/8/10) x 2
6
0.017(1.037)
11:1
1.01 (148.5)
261 (350) at 900 rpm
16° before minimum volume (BMV)
Mobil 446
0.37 (0.35)
No. 2
30
Baseline
Low-NO*
900 (100%)
1566 (2100) (100%)
1503 (9.8%)
97.7(775)
225(0.37)
2.75(7009)'
16.0° BMV
9.02-9.23(1320-1350)
305 (89)
417(292)
324 (124)
338 (149)
150 (22.0)
4.05 (535)
0.02414
757 (903)
636 (686)
36.3
304 (88)
97.3 (28.82)
37
900 (100%)
1567(2101)1100%)
1505(99.8%)
101 (798)
231 (0.38)
2.84(7218)'
10.5° BMV
8.20-8.34 (1200-1220)
291 (66)
414(286)
327(130)
340 (153)
176(25.7)
4.52 (598)
0.02223
754 (898)
625 (665)
35.3
290 (63)
98.2 (29.07)
45
'Heat input accounts for the heating value of lube oil burned by the engine.
exceeding 10 percent of their guideline
are noted in Table 2.
Table 2 shows that several trace
elements were emitted at levels up to
eight times their respective guidelines.
For comparison, emissions of the
gaseous pollutants CO, SO2, and SO3
were at levels ranging from 2 to 20 times
their guidelines; NOx emissions were at
levels over 300 times its guideline. These
comparisons suggest thattheNOxcontrol
achieved may be the most significant
change.
Analyses of SASS train samples for
POM and other organic compounds (the
semivolatile organic priority pollutants
species) were performed. Only
naphthalene, fluoroanthene, phenanth-
rene/anthracene, and pyrene were
detected in the baseline test exhaust gas
at levels of 7 to 70 //g/dscm. Levels of
these compounds in the low-NOx test
exhaust gas were lower, from less than 1
to 50 /ug/dscm.
SASS train organic extract samples
were subjected to LC fractionation, with
TCO, GRAV, IR, and LRMS analysis of LC
fractions, in attempts to elucidate the
chemical character of the exhaust gas
organic material. These analyses
suggested that the exhaust gas organic
for both tests was primarily aliphatic
hydrocarbons with some esters,
carboxylic acids, phenols, mercaptans,
-------
Table 2. Summary of Exhaust Gas Emissions'
Compound
Baseline Test
(ng/J Heat
Input)
(mg/dcsm)
Low-NOt
(ng/J Heat
Input)
(mg/dscm)
Occupational
Exposure
Guideline
(ug/dscmf
Criteria Pollutants and
Other Vapor Species
CO
TUHC(asC3H6)
S03
Solid paniculate
Condensible paniculate
Total semivolatile organics
Total nonvolatile organics
1.490
130
45
44
11
29. 5
3.3
1.1
3.5
1,940
170
59
57
14
38.4
4.5
1.5
4.6
1.040
98
42
95
19
36.6
1.2
12.2
/,230
117
50
113
23
43.7
1.4
14.5
6.0
55
_C
5.0
1.0
10.0"
Trace Elements
Phosphorus, P
Copper, Cu
Iron, Fe
Silver, Ag
Potassium, K
Sodium, Na
Calcium, Ca
Aluminum, Al
Zinc, Zn
Chromium, Cr
Lead, Pb
Nickel. Ni
Selenium. Se
>0.61
0.062
0.020
0.0085
>1.1
>0.63
>0.54
0.53
0.065
0.0020
0.0007
0.012
0.020
XJ.79
0.081
0.026
0.011
>1.4
>0.82
X3.70
0.69
0.085
0.0026
0.0009
0.0/5
0.026
0.045
0.34
0.92
<0.0017
XJ.60
>0.55
—
0.0/0
0.23
0.0/0
0.0072
0.0034
0.023
0.054
0.40
/./
<0.0020
XJ.72
>0.65
—
0.0/2
0.27
0.0/2
0.00087
0.004 1
0.027
0.10
0.1 Of
1.0
0.010
2.09
2.09
2.0
2.0
1.0
O.O5O
0.050'
0.10
0.20
'Exhaust Ox and COx levels were 13.7 and 5.3 percent, respectively, for the baseline test and 14.3 and 5.0 percent, respectively, for the low-NOi test.
''Time-weighted-average TLV unless noted.
°/Vo occupational exposure guideline applicable.
"For nuisance paniculate.
'Sample lost.
18-Hr time-weight-average OSHA exposure limit.
and low-molecular-weight fused-ring
aromatics (e.g. naphthalene and alkyl
naphthalenes).
Bioassay tests were performed on the
organic sorbent module extract from the
SASS trains for both tests. The health
effects bioassay tests performed were the
Ames mutagenicity assay, and the CHO
cytotoxicity assay. The results of these
assays are summarized in Table 3. The
results suggest that the exhaust gas
under both baseline and low-NO x
operation is of moderate to high toxicity
and moderate mutagenicity. This is a
typical bioassay response for combustion
source SASS train XAD-2 extract.
Table 3. Bioassay Analysis Results
Sample
XAD-2
Extract
XAD-2
Extract
Bioassay Analysis
Test
CHO'
Ames
Baseline
H
Low-NO * H/M
M
M
*H = High toxicity, M - Moderate toxicity.
tiM = Moderate mutagenicity.
•&U. S. GOVERNMENT PRINTING OFFICE: 1986/646-116/20797
-------
C. Castaldini is with Acurex Corp., Mountain View, CA 94039.
Robert E. Hall is the EPA Project Officer fsee below).
The complete report consists of two volumes entitled "Environmental Assessment
ofNOx Control on a Compression-Ignition, Large-Bore, Reciprocating, Internal-
Combustion Engine:"
"Volume I. Technical Results." {Order No. PB 86-155 819/AS; Cost: $16.95,
subject to change).
"Volume II. Data Supplement."(Order No. PB 86-155 827/AS; Cost: $16.95.
subject to change).
The above reports will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S7-86/001
000Q329 PS
60604
------- |