Particulate Matter Source Emission Testing - Craig Thiry and Kevin Crosby The Avogadro Group, LLC Oregon - California - Arizona
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Source Emissions Testing and Emissions Specialists
Particulate Matter
Source Emission Testing
Craig Thiry and Kevin Crosby
The Avogadro Group, LLC
Oregon – California - Arizona
Cemtek Users Group Conference 2012
The Need for Testing PM2.5, PM10
Total PM or Filterable PM
Compliance with various regulations
• Permit Limits – driven by NSR, PSD
• MACT or NSPS emission limits
• Emission Factors for Quarterly Reporting
(factors input to DAHS to calculate emissions)
• Correlation Tests for PMCEMS or PMCPMS
(filterable PM only – what’s particles in the stack)
Data for Future Needs
• Baseline data for future permitting
• Emission inventories and inputs to AQ models
PM Measurement Challenges
• Lowering emission limits
• Addition of Condensable Particulate
Matter (CPM) for some situations
• Bias in the measurement of CPM
emissions (historical methods)
• Test methods may not measure low
enough to quantify low-concentration
emissions (see chart on next slide)
Limits in 1970’s as high as
125 mg/m3 (125 mg in ~1-hour test run)
Limits Today much lower
2 to 15 mg/m3 (actual results even lower)Changing Emission Limits
0.1
0.09 lb/MMBtu
0.08
0.07 NSPS (FPM only) 1970’s – first 2 bars here
0.06
0.05
and NSR in Calif (FPM + CPM) since 1980’s
0.04
0.03
0.02
0.01
0What are we trying to Measure? • Modern solid-fuel plants or gas-fired plants Low concentrations of mostly tiny particles (almost all is PM10 or PM2.5 or smaller) • Require accurate data for: - Primary, Directly emitted PM2.5 - Precursor gases to formation of Secondary PM2.5 (SO2, NOX, VOC, NH3)
What are we trying to measure?
Primary Particulate Matter
Photochemistry – other Gases
Primary PM2.5 Emissions (precursors) to Secondary PM2.5 and
- Particles to gaseous smog (ozone, etc.)
- Condensable PM from some Gases Gaseous
just after release to atmosphere G→smog
P smog (O3)
G G P C ↑
G→S P P
G→C G→S G→S P
P G G S S
C S
Ambient Monitor –
G Standard stack tests collects all P C &S
P – Easily measure
G Particles and Gases Ambient PM2.5 commonly
P at stack conditions mostly secondary, and this
GG determines NAAQS attainment
G
But we must measure Primary Emissions
- Particles and Condensable Particles
- Gases kept separate as Precursors
(use models to predict Secondary PM2.5 & smog)Typical sampling arrangement
PM Sampling Apparatus Diagram In-Stack Filter and Impingers
“Traditional” methods • Filterable PM collection is straightforward (not an issue or problem) • Condensable PM collected by bubbling through water in impingers – works great! – this maximizes gas/liquid contact • BUT - Salts form from dissolved gases – The salts become part of the CPM we measure (an Artifact of the test method) • Example: Ammonia and SO2 dissolve and form ammonium sulfate (NH4)2SO4 which is measured as CPM – results biased high
Example of Traditional Method • Sample bubbled through impingers Impingers stand about 18 inches tall. The photo shows a typical set of impingers, the first three with water and the 4th containing silica gel to dry the sample gas. The next slide shows impingers “in action” with sample bubbling through them.
MAXIMIZED GAS-LIQUID CONTACT
What to Do? “New 202” • Promulgated December 2010 • Condensable PM collected by condensing into “dry” impingers – no bubbling through water – this minimizes gas/liquid contact • Collects condensed aerosols or particles: - semi-volatile organic compounds - inorganic aerosols SO3 + H2O → H2SO4 Hypothesis: the dry-impinger method will collect significantly less artifact Lab studies indicated 40 to 80% less sulfate artifact (as much as 85 to 95% for some high- SO2 sources). Does it really work?
Results Comparison From Early Tests
CPM emissions by EPA 202 and OTM-028
Logarithmic Scale
0.100
EPA 202
CPM emission rate, lb/MMBtu
OTM 028
0.010
Pow er
(EPA 202)
0.001 Pow er
(OTM 028)
0.000
0.1 1 10 100
SO2 concentration, ppm vol dry
These are results from a variety of sources, 2007 to 2009 with trend lines
for each of the two methods. OTM-028 (draft 202) results were higher
than Old 202 for low-emitting sources with low SO2.CPM
CPMemissions
emissions by
by EPA
EPA Old
Old 202
202 and New 202
Linear Scale, vs.
Logarithmic SO2
Scale
0.030
CPM emission rate, lb/MMBtu
0.100
CPM emission rate, lb/MMBtu
0.025 Old 202
Old 202
New 202
0.010
0.020 New 202
Linear (Old 202)
Pow er (Old
0.015 Linear202)
(New 202)
Pow er (New
202)
0.001 0.010
0.005
0.000
0.1
0.000 1 10 100
0 5 10 15 20
SO2SO2
concentration, ppm
concentration, ppm vol dry
vol dry
These are results from 2010 and 2011 distributed according to SO2. The
New and Old 202 gave similar results and neither trended with SO2.
There are results around 0.010 and around 0.001 throughout the range.CPM by Old and New EPA 202
Linear Scale, vs. NH3
0.030
CPM emission rate, lb/MMBtu
0.025
0.020
0.015
Old 202
New 202
0.010
Linear (Old 202)
0.005 Linear (New 202)
0.000
0 5 10 15 20
NH3 concentration, ppm vol dry
These are results from 2010 and 2011 distributed according to NH3. The
New and Old 202 gave similar results generally trending with NH3. The
data points around 0.010 have both high NH3 and SO2. The data points
around 0.001 have NH3 of 2 ppm and below, no matter the SO2.CPM Emissions by Old and New EPA 202
Gas-Fired Plants Only
Old 202
New 202
0.0018
Linear (Old 202)
0.0016
Linear (New 202)
0.0014
CPM lb/MMBtu
0.0012
0.001
0.0008
0.0006
0.0004
0.0002
0
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
SO2 Concentration, ppm vol dry
Data from just gas-fired boilers and gas turbines; some of the SO2
concentrations shown are estimated. Little difference Old/New Method.CPM Emission Measurement Comparison
by Old and New EPA Method 202
0.014
CPM emission rate, lb/MMBtu
0.012
0.010 OldA 202
0.008 New 202
0.006
0.004
0.002
0.000
0.1 0.2 0.4 0.8 1 1.9 3.6 11 18 31 38 41
Stack gas SO2, ppm vol dry
Results are arranged according to SO2 concentration, X-axis is not linear.
These are from a variety of sources with more variables than just the SO2
concentration. The highest SO2 sources did not have the highest results.CPM Emission Measurement Comparison
by Old and New EPA Method 202
0.014
CPM emission rate, lb/MMBtu
0.012
OldA 202
0.010
New 202
0.008
0.006
0.004
0.002
0.000
0.02 0.1 0.3 0.3 0.4 0.5 0.7 2 2 5 6.8 15.3
Stack gas NH3, ppm vol dry
These are the same results as the previous slide, arranged by NH3. The data
points with the highest SO2 had low NH3, so are middle and left in this graph.Progress so far
• Initial tests often had • Improved technique
results higher than and reagents have
the old method solved this problem
• Method can easily • Equipment
cost a 20% premium improvements may
over the old method eventually save labor
• Lab technique will
always take more
labor
The Hypothesis is NOT PROVEN by our data
– there is only slightly less artifact for low emittersCan we Improve the Situation? • Reduce Ammonia Slip (below about 2 ppm) • Correct the results for ammonium salts - some have suggested using controlled condensation test results for the inorganic fraction • Use a Dilution method (measure filterable and condensable together) - EPA “conditional test method” CTM-039
Controlled Condensation • ASTM is working on a standard method • EPA has accepted NCASI Method 8A for some uses (CTM-013) • CC accurately measures SO3 and SO2 from almost any type of source (even when NH3 is high) • SO3 would count as CPM; SO2 would not! • Example – Gas Turbine SO3 ~ 15 to 50% of Total SOX – so using this might reduce the inorganic CPM significantly from what we measure with Old or New 202. Would be even more beneficial for Coal-fired power plants with SCR.
Dilution Sampler Concept
Stack emissions of Primary PM2.5
Emissions into a "virtual" stream of air
Photochemistry
Particles Secondary + Primary PM2.5
+ Condensables
Stream of air + Gases
Ambient sampler PM2.5 filter
Stack sampling of Primary PM2.5 by CTM-039
Sample "emitted" into a stream of air
Primary PM2.5 - Particles and Condensables (and Gases)
Sampled through filter
same as Ambient sampler
Stream of air Gases remain as gases, no secondary PM2.5CTM-039 • Designed to emulate dilution of stack emissions in ambient air • Condensables form in the same way as in actual emissions – EPA’s Gold Standard • Primary PM2.5 – particles and CPM - all sampled together (like ambient sampling) • Shows promise – the results of comparative studies are encouraging • Disadvantage: Expensive new equipment
A result of 1 mg/m3 (CCGT) is about the same level as a blank sample. Boilers were solid fuel with SNCR. Boiler A was tested once by New 202 with the ammonia injection off. CTM-039 can reduce artifact and therefore provide lower results in some cases.
Conclusions • The Hypothesis is true only in certain cases, usually at higher concentrations • New 202 is sometimes a slight improvement from the Old 202 for low-concentration sources • New 202 might not be worth its extra cost - except in some cases (sometimes every little bit helps) • Other alternatives (such as CTM-039) will cost even more - but may provide more representative results for some cases • Results will depend on which gases are present (NH3, SO2, SO3, HCl) and in what relative concentrations • The Method used will define the Results • Quality Testing is critical!
Questions ???
Craig Thiry
Business Development Director
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