1 / 19

Kevin A Cavender EPA-Office of Air Quality, Planning and Standards

Precursor Gas Monitoring NO y Monitoring Training Overview. Kevin A Cavender EPA-Office of Air Quality, Planning and Standards. Outline. Methodology Interferences and operational issues Commercially available NOy Monitors Calibration Current work in progress Summary. Methodology.

kalani
Download Presentation

Kevin A Cavender EPA-Office of Air Quality, Planning and Standards

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Precursor Gas Monitoring NOy Monitoring Training Overview Kevin A CavenderEPA-Office of Air Quality, Planning and Standards

  2. Outline • Methodology • Interferences and operational issues • Commercially available NOy Monitors • Calibration • Current work in progress • Summary

  3. Methodology What is NOy? NOy consists of the sum of all reactive nitrogen oxides. including NO, and NO2, and other nitrogen oxides referred to as NOz. NO + NO2 + NOz = NOy The major components of NOz include nitrous acids [nitric acid (HNO3), and nitrous acid (HONO)], organic nitrates [peroxyl acetyl nitrate (PAN), methyl peroxyl acetyl nitrate (MPAN), and peroxyl propionyl nitrate, (PPN)], and particulate nitrates.

  4. Methodology • Why Measure NOy? • NOy is a precursor to both ozone and PM2.5 formation • Conventional NOx boxes “accidentally” measure some NOz species, but not all.

  5. Methodology Measurement Principles NO is measured based on its chemiluminescent reaction with O3 NO + 03 -> NO2 + hv The amount of light generated is linearly proportional to the concentration of NO. NOy is measured by first passing the sample through a converter that converts NO2 and NOz species to NO and then measuring for NO as above.

  6. Methodology Diagram of a High Sensitivity NOy instrument

  7. Methodology • What makes a high sensitivity NOy monitor different than a conventional (low sensitivity) NOx monitor? • A high sensitivity NOy monitor is very similar to conventional NOx monitors with the following exceptions: • Remote converter is located at sample inlet, not inside monitor • Pre-reactor to reduce non-NOy interferences • Increased sample flow rate • Reduced reaction chamber temperature and pressure

  8. InstallationRemote Converter Remote Converter on 10 meter tower

  9. Interferences and Operational Issues • Reaction of NO with ambient O3 • Ambient ozone will react with NO in sample lines creating negative NO interference • Residence in sample line should be kept to less than 2 seconds • Ammonia • Converter may convert a small amount of ammonia to NO creating positive NO interference • Avoid locating near ammonia sources (e.g., feed lots) • Converter height above ground level and “fetch”

  10. Commercially Available NOy Monitors TAPI 200EU/501 NOy TEI 42CY EC9841A-NOy

  11. Testing Results

  12. NOy Span Response

  13. NOy Precision Response

  14. Histogram of NOy Data Collected at Burden's Creek Site5/1/05-1/29/06 NO NOy NO2 + NOz Percent 0 0-1 1-5 5-10 10-50 50-100 100-200 200+ Concentration (ppb)

  15. Histogram of NOy Data Collected at Burden's Creek Site5/1/05-1/29/06

  16. Instrument OperationInitial Calibration • Note: Supply sufficient calibration gas to ensure excess flow through converter inlet (supply > 5 liters per minute) • Supply zero air until stable readings are obtained (approximately 20-30 minutes) • Adjust monitor to read zero response for NO and NOy. • Supply NO calibration gas at approximately 90% of scale • Adjust monitor after stable NO and NOy readings are obtained • Add ozone to calibration gas to produce NO2 at approximately 70% of scale • Amount NO decreases equals the amount of NO2 created • Calculate conversion efficiency as (NOy-NO)/(NO2 created) • Conversion efficiency should be greater > 96%. • Adjust NO2 + NOz reading to amount of NO2 created

  17. Instrument OperationConverter Efficiency Test • Converter efficiency test designed to challenge converter with more difficult to convert NOy species • N-propyl nitrate, isopropyl nitrate • Supply sufficient calibration gas to ensure excess flow at converter inlet (> 5 liters per minute) • Supply calibration gas at approximately 90% of scale • Allow sufficient time for readings to stabilize • Calculate converter efficiency as – • (NOy reading/Concentration Suppliedx100%) • If converter efficiency is less than 96% the converter should be repaired/replaced

  18. Current Work In Progress • Evaluation of inlet materials for API • Testing HNO3 loss on stainless steel, silico steel, and FTP teflon. • Evaluation of “proof of concept” NO/true NO2/NOy monitor • Two converters • Moly for NOy • High intensity LED for NO2

  19. Questions?

More Related