FTIR For Stack and CEM


Published on

Presentation of the MKS Instruments, MultiGas 2030 FTIR for use in Stack Testing and CEM applications.

  • Be the first to comment

  • Be the first to like this

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

FTIR For Stack and CEM

  1. 1. Recent Developments inFTIR for Stack Emissions and CEM Monitoring in the Power Generation Industry Sylvie Bosch-Charpenay MKS Instruments On-Line Product Group
  2. 2. New RegulationsNew Standards for Combustion Engines– Standards of Performance for Stationary Spark Ignition Internal Combustion Engines : 40 CFR Part 60 subpart JJJJ. Gases to be measured: NOx, CO, THC– National Emission Standards for Hazardous Air Pollutants (NESHAP) for Reciprocating Internal Combustion Engines (RICE): 40 CFR Part 63 subpart ZZZZ. Gases to be measured: NOx, CO, THC, formaldehydeHazardous Air Pollutants– Formaldehyde (year 2013, test on annual basis)– Future speciation of individual HCs (NMHC=non-methane HC’s, methane, ethane)– Methanol, etc… 2
  3. 3. Emission MonitoringStandard methods– NOx : Chemiluminescence (CLD) – lower accuracy in high NO2– CO, CO2 : Non-Dispersive Infrared (NDIR) – separate analyzer for each gas– THC : Field Ionization Detectors (FID) – provides a single number (no speciation)– Electrochemical sensors – separate analyzer for each gasFTIR provides measurements of many gasessimultaneously– CO, CO2, NO, NO2, N2O, NH3, CH4, HCl, HF, ethane, ethylene, propylene, formaldehyde, H2O, etc… 3
  4. 4. FTIR AdvantagesFTIR is cost-effective if more than 4 gases need to bemeasuredFTIR requires minimum calibration and so reduces costsCan be easily (and inexpensively) shipped on-site, instead ofdeploying an entire vehicleFTIR is best method to measure formaldehyde 4
  5. 5. Infrared (IR) SpectroscopyBased on IR light absorption– Energy (IR radiation) heats molecule - vibrations and rotations– The pattern and intensity of the spectrum provides all the information about gas (type and concentration) H2O Spectrum 5
  6. 6. FTIR Provides Real-Time Analysis of Multiple Species 6 Averaging 15 sec to 1 minute per point
  7. 7. Measurements Requirements EPA Methods DIN EN 15277-3 3A, 4, 7E, 10Sensitivity (=short <2% of cal span <2% of cal spanterm repeatability)Accuracy (= <2% of cal span <2% of cal spancalibration error)Interferences <2.5% of cal span. Tested <4% of cal span. Tested(=cross-sensitivity) once. annually.Drift <3% of cal span <2% of cal spanSystem Response _ Typically less than 200 secTime cal span = calibration span = upper limit of calibration range 7
  8. 8. How Can FTIR Meet theMeasurement Requirements?Sensitivity usually not an issue (long acquisitiontimes OK)Accurate FTIR instrument neededOptimization of Analysis Method (minimal effect ofinterferences)Drift usually not an issue (background in N2 takenprior to testing)Optimization of Sampling System (response time,effective transport of “sticky” species) 8
  9. 9. Instrument Spectral Accuracy RequirementsInstrument Accuracy Optimization– Spectra linearity Accurate absorbance in the whole range of absorbance level– Resolution Instrument has same resolution (i.e., line width) as the calibration spectra– Line position Instrument spectra are “lining up” exactly with the calibration spectraValidation– Standard historical approach is to run cal cylinder and create instrument-specific calibration– New, better approach is to use transferrable calibrations (possible because of excellent instrument to instrument matching) and verify cal cylinder 9
  10. 10. Accuracy Validation: Correct Resolution, Line Position and Absorbance Level Comparison of calibration (yellow) to sample (white) for CO 10 => Excellent overlap of calibration and sample spectra
  11. 11. Accurate Multi-Point Calibrations 11 Multiple frequencies and calibration levels
  12. 12. Tuning of Analysis Method to Minimize InterferencesFor minimal interferences, optimized analysis rangeand masking (“picket fencing”)Correction factors included to compensate for matrixeffects (NO, CO) for best accuracyCustom water calibration may be needed (but only forvery low calibration spans)“Canned methods” should be made available bymanufacturerAdditional components can be easily added 12
  13. 13. Ability to Measure NO between Water PeaksSample = 150 ppm NO in 35% H2OTop: sample (white) and water spectrum (red)Bottom: sample minus water (white) and NO calibration (green). Grey 13areas are “picket-fenced” regions which are not used in the analysis
  14. 14. No Interference of Water High SensitivityH2O stepsup to 40% Lowdetection limits No artificial bias even in very high water (up to 40%) Note: The HCl and HF sharp decaying peaks are real and represent small amounts accumulated in transfer lines.14 Other sharp positive and negative peaks are short duration artifacts due to fast water levels changes
  15. 15. Typical Achievable Measurement RangesSpecies Ranges in mg/m3NO 0-30, 0-200, 0-400, 0-1500NO2 0-50, 0-100, 0-1000N2O 0-50, 0-100, 0-500NH3 0-10, 0-75CO 0-75, 0-150, 0-1500HF 0-5, 0-10HCl 0-15, 0-90, 0-200SO2 0-75, 0-300, 0-2000CO2 0-25%H2O 0-40%CH4 0-15, 0-50 15
  16. 16. Optimization of FTIR Sampling SystemHeated probe with filtering– Metal or Glass– Stainless steel filter required for “sticky compounds” HF, HCl, NO2, NH3– <0.1 um recommended (must keep particulate low)Heated sampling line– SS (not Teflon) recommended for most applications– As short a length as possible– Maintain temp – 191 C (very important, no cold spot!)– Maintain pressure – 1.0 Atm (+/- 5% recommended)Sampling pump before or after FTIR Gas Analyzer– Before: Be careful about contamination or sample loss Additional Filtering Possible– After: Be careful not to let pressure go too low 16
  17. 17. Mechanical & Equilibration Response Times 17“Sticky” compounds are the same when H2O is present
  18. 18. Formaldehyde Easy to Measure H2O sample Formaldehyde Sample with 5 ppm formaldehyde and 5% water (broad peaks on right correspond to diesel, also measured) 18
  19. 19. Formaldehyde Testing InStationary Combustion Turbines DL = 200-300 ppb under typical conditions DL as low as 30 ppb under optimized conditions 19
  20. 20. Q&A InformationASTM Method 6348 -03 Standard Test Method for Determination of Gaseous Compounds by Extractive Direct Interface Fourier Transform Infrared Spectroscopyhttp://www.epa.gov/ttn/atw/rice/fr05mr09.pdf 20