Characterizing Source Characterizing Source Emissions Emissions John G. Watson ([email protected]) Judith C. Chow Desert Research Institute Reno, NV, USA Presented at The Workshop on Air Quality Management, Measurement, Modeling, and Health Effects University of Zagreb, Zagreb, Croatia
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Characterizing Source Emissions John G. Watson ([email protected]) Judith C. Chow Desert Research Institute Reno, NV, USA Presented at The Workshop on Air.
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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!
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.
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).
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.