epa precursor gas training workshop so 2 precursor gas monitoring training overview lewis weinstock...
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EPA Precursor Gas Training Workshop
SO2 Precursor Gas Monitoring Training Overview
Lewis Weinstock
Solomon Ricks, U.S. EPA
Office of Air Quality Planning and Standards
EPA Precursor Gas Training Workshop
Outline
• Methodology• Field test results• Responses to Calibrations
• Burden’s Creek SO2 Frequency Distribution
• Instrument Operations• Summary
EPA Precursor Gas Training Workshop
Why measure trace levels of SO2
Objectives:• Emission strategy
development• Effectiveness of
reduction strategies• Validation of SO2 and
sulfate modeling predictions
• Long term trends analysis
• Health effect studiesNeed highly-sensitive ambient monitors deployed around these areas to determine CAIR’s effect on SO2 and related species.
EPA Precursor Gas Training Workshop
Trace Level Sampling Challenges (SO2)
• Performance challenges– Lower noise for reduced LDL/MDL– Reduced zero and span drift– Increased rejection of interferences
• Trace level modifications– Special band-pass filter to increase NO rejection– Improved light baffling to reduce stray light– More powerful UV source lamp– Higher detector sensitivity– Longer optical bench
EPA Precursor Gas Training Workshop
Methodology (UV Light Path)
SO2 + hv214nm SO2*
SO2* SO2 + hv330nm
EPA Precursor Gas Training Workshop
Methodology (General Schematic)
General Diagram of a Precursor Gas SO2 Analyzer
EPA Precursor Gas Training Workshop
Currently Available Trace-Level SO2 Options
Teledyne-API 100EUEQSA-0495-100
Ecotech EC9850TEQSA-0193-092
Thermo Electron 43C-TLEEQSA-0486-060(new model: 43i-TLE)
EPA Precursor Gas Training Workshop
Testing Results – FieldApril 2006
Make/Model Thermo 43C-TLE (observed)
Averaging Time 60 seconds
Conc. Range 0-100 ppb
Zero Drift (0.200 ppb/day) 12 hr. (0.199 ppb)24 hr. (0.200 ppb)
Span Drift (1% FS per week) 20% FS (0.06%)80% FS (0.27%)
Precision (Coefficient of Variance)
0.91%
Bias +1.08%
LDL (0.100 ppb) 0.112 ppb
Noise (0.050 ppb) 0.029 ppb
Linearity (1% FS. M, B, and R2 reported)
1.0163x-0.454
R2 = 0.9995
MDL Observed 0.055 ppb (0.038 – 0.148 ppb CL)
EPA Precursor Gas Training Workshop
SO2 TEI - Zero Drift - Burdens Creek
-0.5
-0.4
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
EPA Precursor Gas Training Workshop
SO2 TEI - Span Drift at 90 ppb - Burdens Creek
-20.0%
-15.0%
-10.0%
-5.0%
0.0%
5.0%
10.0%
15.0%
20.0%
Recertified Environics calibrator
EPA Precursor Gas Training Workshop
SO2 TEI - Precision Drift at 10 ppb - Burdens Creek
-20.0%
-15.0%
-10.0%
-5.0%
0.0%
5.0%
10.0%
15.0%
20.0%
Recertified Environics calibrator
?
EPA Precursor Gas Training Workshop
Burdens Creek – Ambient Concentrations
Precision Level
Span Level
EPA Precursor Gas Training Workshop
Burdens Creek – Ambient Concentrations
Burdens Creek Frequency Distribution - SO2
-2
0
2
4
6
8
10
12
99 90 75 50 25 10 1
Percentile
pp
b
EPA Precursor Gas Training Workshop
Thermo 43C-TLE Diagnostic Parameters (5-11-07)
TEI Diagnostics Actual Reading Acceptance Criteria Acceptable?
Range 100 0 - 100 ppb Y
Averaging Time 60 10 – 300 seconds Y
SO2 Background 3.36 0 – 10 ppb Y
SO2 Span Coefficient 1.030 0.800 – 1.200 Y
PMT Voltage -604 ~ -600 V Y
Lamp Voltage 1211 500 - 1200 V N
Power (+5/+15/-15/Battery) 4.9/14.9/-14.9/3.4 + 0. 1V, >3.0 V Y
Internal temperature 36.8 8 – 47 degC Y
Chamber Temperature 45.2 43 – 47 degC Y
Chamber Pressure 729.5 650 – 760 mmHg Y
Sample Flow 0.587 0.5-1.0 l/min Y
UV Lamp Intensity 13,947 10,000 – 50,000 Hz Y
Change Particle Filter Y N Respan 89.8 PPB
EPA Precursor Gas Training Workshop
Instrument Operation
Item Schedule
Check diagnostics (if not available remotely) Bi-weekly
Visual inspection and cleaning 6 months
Replace sample particulate filter Bi-weekly to monthly based on PM levels
Perform QC gas challenge (Level 1 and precision)
Bi-weekly (daily recommended)
Capillary inspection and replacement 6 months
Fan filter inspection and cleaning 6 months depending on surroundings
Lamp voltage check When lamp voltage approaches maximum (1200v)
EPA Precursor Gas Training Workshop
Interferences
•Hydrocarbons
•Fluoresces in a fashion similar to SO2 when exposed to UV light
•Removed through the hydrocarbon “kicker”
•Nitrogen oxide
•NO fluoresces in a spectral range close to SO2
•Band pass filter enhances NO rejection
EPA Precursor Gas Training Workshop
NO Rejection Test
0
20
40
60
80
100
120
NO
Con
cent
ratio
n, p
pb
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
SO2
Con
cent
ratio
n, p
pb
NO SO2
SO2 Response due to NO interference