Characterizing Source Emissions John G. Watson ([email protected]) Judith C. Chow Desert Research...
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Transcript of Characterizing Source Emissions John G. Watson ([email protected]) Judith C. Chow Desert Research...
Characterizing Source EmissionsCharacterizing Source EmissionsJohn G. Watson ([email protected])
Judith C. Chow
Desert Research InstituteReno, NV, USA
Presented at
The Workshop on Air Quality Management, Measurement, Modeling, and Health Effects
University of Zagreb, Zagreb, Croatia
24 May 2007
ObjectivesObjectives
•Review past and current source sampling methods for PM emission rates and source profiles
• Illustrate recent testing protocols for dilution sampling systems
Important Emissions SourcesImportant Emissions Sources• Fugitive dust from wind erosion, agricultural activities,
construction, storage piles, and vehicle traffic on paved and unpaved roads.
• Ducted exhaust from industrial facilities (e.g., coal- and oil-fired power stations, smelting, cement plants, chemical plants, petroleum extraction and refining, glass manufacturing, paper making, shipping).
• Vehicle exhaust from cars, trucks, motorcycles, and buses.
• Burning and cooking from stoves, charbroilers, trash, forest fires, and agricultural burning.
• Ammonia from animal husbandry and fertilization.
Important Emissions CharacteristicsImportant Emissions Characteristics• Emissions Rate:
Amount emitted per unit time or unit of activity.
• Particle Size:Determines transport and deposition properties.
• Chemical Composition:Fractional abundance of gaseous and particulate chemical components in emissions. Used to speciate inventory and to apportion ambient concentrations to sources.
• Temporal Variation:Emissions change on daily, weekly, seasonal, and annual cycles. Timing of emissions affects atmospheric transport and dilution as well as human exposure to outdoor air pollution.
Emissions are Measured for Different Emissions are Measured for Different PurposesPurposes• Certification:
Verify that a process design is capable of achieving emissions below a regulated limit. (e.g., FTP engine tests)
• Compliance: Determine that in-use processes are within permitted values (e.g., vehicle smog tests, periodic stack tests, opacity tests)
• Emissions trading: Relate actual emissions to allowances (e.g., continuous SO2 monitors).
• Emission inventories: Real-world emissions for pollution planning.
• Source apportionment: Speciated emissions for source and receptor modeling.
•Emissions measured for one purpose are typically inaccurate for other purposes!
Emissions ModelEmissions Model
Component i emissions fluxes =
Σij fraction of component i in source j
x emission factor (mass/activity) for source j
x activity of source j
x [particle size fraction]
x [control efficiency]
x [temporal profile]
PM Source ProfilesPM Source ProfilesVehicle Exhaust
0.001
0.01
0.1
1
10
100
Chl
orid
e
Nitr
ate
Sul
fate
Am
mon
ium
Sol
. Pot
as
Org
anic
Car
bon
Ele.
Car
bon
Alu
min
um
Silic
on
Pho
spor
us
Sul
fur
Chl
orin
e
Pota
ssiu
m
Cal
cium
Tita
nium
Va
nadi
um
Ch
rom
ium
Man
gane
se Iron
Nic
kel
Cop
per
Zin
c
Ars
enic
Sel
eniu
m
Bro
min
e
Str
ontiu
m
Lead
Chemical Compound
Ab
un
dan
ce
(%)
Wood Burning
0.001
0.01
0.1
1
10
100
Chl
orid
e
Nitr
ate
Sulfa
te
Amm
oniu
m
Sol
. Pot
as
Org
anic
Car
bon
Ele.
Car
bon
Alu
min
um
Silic
on
Phos
poru
s
Sulfu
r
Chl
orin
e
Pot
assi
um
Cal
cium
Tita
nium
Van
adiu
m
Chr
omiu
m
Man
gane
se Iron
Nick
el
Copp
er Zinc
Arse
nic
Sel
eniu
m
Brom
ine
Stro
ntiu
m
Lead
Chemical Compound
Abu
nda
nce
(%)
Road Dust
0.001
0.01
0.1
1
10
100
Chl
oride
Nitr
ate
Sul
fate
Amm
oni
um
Sol
. Pot
as
Org
anic
Ca
rbon
Ele
. Ca
rbon
Alu
min
um
Silic
on
Pho
spor
us
Sul
fur
Chlo
rine
Pot
assi
um
Cal
cium
Tita
nium
Vana
diu
m
Chr
omiu
m
Man
gan
ese Iron
Nic
kel
Co
ppe
r
Zinc
Ars
enic
Sele
nium
Bro
mine
Str
ontiu
m
Lead
Chemical Compound
Abu
ndan
ce (
%)
Coal-fired Power Plant
0.001
0.01
0.1
1
10
100
Chl
orid
e
Nitra
te
Sulfa
te
Am
mon
ium
Sol
. Pot
as
Org
anic
Car
bon
Ele
. Ca
rbon
Alum
inum
Silic
on
Pho
spor
us
Sul
fur
Chl
orine
Pot
assi
um
Cal
cium
Tita
nium
Vana
dium
Chr
omiu
m
Man
gane
se Iron
Nick
el
Cop
per
Zinc
Ars
enic
Sel
eniu
m
Brom
ine
Stro
ntiu
m
Lead
Chemical Compound
Abu
ndan
ce (
%)
Emissions Rates/Factors Emissions Rates/Factors (PM(PM1010, PM, PM2.52.5, SO, SO22, NO, NOXX, NH, NH33))
• Existing gridded inventories: specialized modeling studies
• Emissions factor models: http://www.epa.gov/OMSWWW/models.htm http://www.epa.gov/ttn/chief/
• Continuous emission monitors: http://www.epa.gov/acidrain/edata.html
• Large point sources: http://www.epa.gov/airsweb/
Inventory GIS Activity LayersInventory GIS Activity Layers
• Land use and terrain: geological survey, satellite
• Population: Census
• Roadways: Census, mapping companies
• Soil and coal types: Soil Conservation Service
• Fuel volumes and composition: sales records, taxes, certification tests
• Light-medium commercial/industrial: Census, stock listings
• Large point sources: Census, production records
Important Sources of Primary PM Important Sources of Primary PM and Secondary Precursorsand Secondary Precursors
• PM Fugitive dust from wind erosion, agricultural activities, construction, storage piles, and vehicle traffic on paved and unpaved roads.
• PM, NOx, VOC, SO2 Ducted exhaust from industrial facilities (e.g., coal- and oil-fired power stations, smelting, cement plants, chemical plants, petroleum extraction and refining, glass manufacturing, paper making, shipping).
• PM, NOx, VOC, SO2 Vehicle exhaust from cars, trucks, motorcycles, and buses.
• PM, VOC Burning and cooking from stoves, charbroilers, trash, forest fires, and agricultural burning.
• NH3 Animal husbandry and fertilization.
Source Characterization Source Characterization Measurement MethodsMeasurement Methods
• Laboratory suspension: Dust or residue samples resuspended in laboratory chamber.
• Source-dominated sampling: Samples taken at locations and times when a single source dominates ambient concentrations.
• Vehicle dynamometer testing: Simulate driving cycles on fixed roller.
• Vehicle on-road testing: Roadside or tunnel, integrated or individual vehicle samples
• Diluted duct sampling: Samples drawn into aging chamber and cooled with clean air.
Laboratory Dust ResuspensionLaboratory Dust Resuspension
Source-Dominated SamplingSource-Dominated SamplingUnpaved Road Dust EmissionsUnpaved Road Dust Emissions
Road Dust EmissionsRoad Dust Emissions
•Use TRAKER (Testing Re-entrained Aerosol Kinetic Emissions from Roads) vehicle to map road dust emissions.
•Calibrate TRAKER with unpaved road dust emissions.
TRAKER MeasurementsTRAKER Measurements
Location of inlets (right side and
background shown).
Generator and pumps are mounted on a
platform on the back of the van.
TRAKER Measurements TRAKER Measurements (continued)
Two sampling plenums, DustTrak and GRIMM particle
monitors, and rotameters.
GPS logs the TRAKER’s position every 1
second.
Results from the Treasure Valley, Results from the Treasure Valley, Idaho, Road Dust StudyIdaho, Road Dust Study
Source-Dominated SamplingSource-Dominated Sampling(Cooking)(Cooking)
Real-World Cooking Simulated Cooking
New Vehicle Emissions Testing New Vehicle Emissions Testing MethodsMethods• Remote Sensing of Vehicle Emissions:
Allows emission rates to be determined for certain chemical components (VOC, NOX, CO, PM).
• Fast Response VOC and NOX Speciation Measurements and Normalizing to CO2: Can determine individual on-road vehicle emissions with respect to fuel consumption. Can be applied to other sources with high emissions of other gases.
• Dense Spatial Monitoring: Battery-powered PM monitors as well as passive VOC, NO2, and CO absorbers are located within and around source complexes. Emissions are inferred from complex dispersion models or spatial receptor models.
• Tunnel Studies: Measurements are taken in tunnels to minimize contamination from other sources (VOC, NOX, CO, PM).
Source-Dominated SamplingSource-Dominated Sampling((Vehicle Exhaust)Vehicle Exhaust)
Roadside sampling Diesel exhaust sampling
Estimate Emissions of Vehicle Estimate Emissions of Vehicle ExhaustExhaust
• Sample real-time CO2 and pollutants in a source-dominated environment to obtain fuel-based emissions factors.
• Use road tube counters to classify vehicles.
• Use area fuel sales to estimate emissions.
• Compare results with MOBILE6 emissions factors.
Estimate Vehicle Estimate Vehicle Exhaust Emission RateExhaust Emission Rate• Fourier Transform Infrared
Spectroscope measures CO2, CO, NO2, NO, and propane.
• Correlation of pollutants with CO2 yields fuel-based emissions factors.
• Real-time particle counters (e.g., Grimm 1.108) can quantify particles between 0.3 to 1.8 µm at 1-sec resolution.
Remote Sensing of In-Use Vehicle Remote Sensing of In-Use Vehicle ExhaustExhaust
TRANSMITTER
TerminusPlate
ExhaustPlume
BackscatteredLight
Lic #
DATAACQUISITION
Absorption and Backscatter
~10-15 m
RECEIVER
LORAX: Lidar On-Road Aerosol LORAX: Lidar On-Road Aerosol ExperimentExperiment
In-Plume Vehicle Emission SamplingIn-Plume Vehicle Emission Sampling
Ducted Emissions: Hot sampleDucted Emissions: Hot sample
• Total Suspended Particulate (TSP)
– EPA Method 17: in-stack filter (at stack temperature)
– EPA Method 5: heated out-of-stack filter (at 120 or 160 °C)
¤ EPA Method 5, 5A, 5B, 5C, 5D, 5F, 5G, 5H, 5I
• PM10 and PM2.5, including condensable PM
– Method 201A: combines Method 17 with in-stack 10 µm cyclone to collect PM10
– Method PRE-004: combines Method 201A with in-stack 2.5 µm cyclone to collect PM2.5
– EPA Method 202: collect condensable PM as those which pass through filter and are captured in water-filled bubblers (impingers) in an ice bath
Method 201/202 Filter/Impinger MethodsMethod 201/202 Filter/Impinger Methods
EPA Methods PRE4 & 202
Filterable PM
Condensable PM (<1 µm)
PM10 and PM2.5cyclones and
filter(in-stack)
VTT
Filter
Glass orTeflon®
probe liner(heated)Teflon®
tubing(heated
Sample gas is cooled to 60-70F in iced impingers
Analysis:
• Organic extraction
• Titration of inorganic fraction
• Dry and weigh organic and inorganic residue
• SO4= and Cl-
Analysis:
• Evaporation of rinses
• Gravimetric analysis
Post Test Purge with N2 or AirRange of chemical
speciation techniques is limited due to high
temperatures, moisture, interfering
particles & gases
Method 202 ArtifactMethod 202 Artifact
Findings
• Condensable PM2.5 may be overestimated using impinger-based methods
– Sulfate artifacts significant even for gas-fired sources
– If Method 202 is performed, a post-test nitrogen purge should always be done
– Further investigation of artifacts and differences between impinger and dilution sampling methods is needed
• Dilution sampling allows broader speciation of PM2.5 for improved speciation profiles
Difference in PMDifference in PM2.52.5 Mass Mass
between In-Stack and Dilution Samplingbetween In-Stack and Dilution SamplingGas-Fired Boiler - Field Data
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0.016
0.018
Run 1 Run 2 Run 3 Run 1 Run 2 Run 3 AP42
lb/M
MB
tu
inorganic condensable (M202)organic condensable (M202)Filterable PM (M201A)PM2.5 (dilution)
Dilution Method
In-Stack Methods
Dilution Sampling of Dilution Sampling of Emissions from Meat CookingEmissions from Meat Cooking
Dilution Sampling SystemDilution Sampling System
aa
StackGas
HEPAFilter
CarbonFilter
Rotameter
VenturiProbe
T
RH
AmbientAir
Flow Control
Pump
ResidenceTime
ChamberPM2.5
Cyclones
To SampleCollection
Trains
•Stainless steel
•Cross-flow jet mixing
•Dilution Ratio 10-40:1
•Residence time 80-90 sec
Sample gas is cooled to ambient temperature by dilution with ambient air
Flow meter
PM10 Cyclone
Particle Characteristics Often Vary Particle Characteristics Often Vary During Emissions TestsDuring Emissions Tests(ELPI and Grimm OPC Size Distributions)(ELPI and Grimm OPC Size Distributions)
Mass concentration Number concentrationDp (um)
dp
0.1
1.0
2.5
Shakeout (15min)
Shakeout (15min)
Nucleation/ reactions from binder
Pouring
Loose sand mass
Recently Developed DRI/BEI Dilution SystemRecently Developed DRI/BEI Dilution System26”
12.5”
28”
8.5”
7”
3”A
B
C
A: 1.875 in
B: 5.875 in
C: 8.375 in
Inner Diameter
Thermocouple Positions on each Collar• Red points are
measurement points 0.5”, 1.25”, 1.75”, 2.25” and 2.875” (center) from inner wall.
• Grey rods indicate thermocouple locations and typical starting points for each thermocouple
Recently Developed DRI/BEI Dilution System Recently Developed DRI/BEI Dilution System (continued)(continued)
Thermocouples 1, 6, 10
Thermocouples 2, 7, 11
Thermocouples 3, 8, 13
Thermocouples 4, 9, 14
Thermocouples 5, 10, 15
Characterizing the DRI/BEI Dilution Characterizing the DRI/BEI Dilution SystemSystem
• Temperature profile at different depths and along various distances from inlet.
• Determine loses and mixing characteristic as a function of particle size, dilution ratios, and distance from inlet for polystyrene latex sphere (PSL) particles from 0.06 – 30 µm.
• Determine optimum range of dilution ratios and aging time using a diesel generator at idle and full load.
Diluted Stack Test FindingsDiluted Stack Test Findings
• Residence time and dilution ratio do not change particulate mass emission rate, but do affect size distribution and total number of particles emitted. Longer residence times shift particulate mass to larger size and decrease total number concentration.
• Higher dilution rates increase ultrafine particle concentrations.
ConclusionsConclusions• Road dust emission potential can be measured
continuously.
• Mobile emissions are more accurate from on-road sensing of many vehicles than from dynamometer testing of a few vehicles.
• Dilution sampling provides more accurate estimates of PM stack emission rates than hot stack and impinger samples.
• Chemical source profiles should be measured with emission rates.