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SO2 Precursor Gas Monitoring Training Overview

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Presentation on theme: "SO2 Precursor Gas Monitoring Training Overview"— Presentation transcript:

1 SO2 Precursor Gas Monitoring Training Overview
Lewis Weinstock Solomon Ricks, U.S. EPA Office of Air Quality Planning and Standards

2 Outline Methodology Field test results Responses to Calibrations
Burden’s Creek SO2 Frequency Distribution Instrument Operations Summary

3 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 studies Need highly-sensitive ambient monitors deployed around these areas to determine CAIR’s effect on SO2 and related species.

4 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

5 Methodology (UV Light Path)
SO2 + hv214nm SO2* SO2* SO2 + hv330nm

6 Methodology (General Schematic)
General Diagram of a Precursor Gas SO2 Analyzer

7 Currently Available Trace-Level SO2 Options
Teledyne-API 100EU EQSA Thermo Electron 43C-TLE EQSA (new model: 43i-TLE) Ecotech EC9850T EQSA

8 Testing Results – Field April 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 = MDL Observed 0.055 ppb (0.038 – ppb CL)


10 Recertified Environics calibrator

11 Recertified Environics calibrator

12 Burdens Creek – Ambient Concentrations
Span Level Precision Level

13 Burdens Creek – Ambient Concentrations

14 Thermo 43C-TLE Diagnostic Parameters (5-11-07)

15 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 Fan filter inspection and cleaning 6 months depending on surroundings Lamp voltage check When lamp voltage approaches maximum (1200v)

16 Hydrocarbons Nitrogen oxide Interferences
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

17 SO2 Response due to NO interference

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