![FTIR Analysis Method
Analytical Method
– Classical Least Squares [CLS]
– Predict chemical concentrations using spectroscopy (FTIR) and
linear algebra
Calibration Method
– Requires certified gas or liquid standard – NIST Traceable
– Collect signal/spectrum from FTIR
– Combine and model using CLS
– Analysis Region dependant upon component concentration
Determining Sample Gas Concentration
– Run sample gas through FTIR gas cell
– Collect signal/spectrum from FTIR
– Use calibration model to predict sample gas concentration
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Method for HCL Monitoring by FTIR Analysis
- 1. MKS Analytical Method for HCl by FTIR
- 2. FTIR Analysis Method Analytical Method – Classical Least Squares [CLS] – Predict chemical concentrations using spectroscopy (FTIR) and linear algebra Calibration Method – Requires certified gas or liquid standard – NIST Traceable – Collect signal/spectrum from FTIR – Combine and model using CLS – Analysis Region dependant upon component concentration Determining Sample Gas Concentration – Run sample gas through FTIR gas cell – Collect signal/spectrum from FTIR – Use calibration model to predict sample gas concentration 2
- 3. Calibration Summary Region Selection – Select ALL regions where compound is present in the spectrum Analysis Band – Select the largest peak region – Modify Analysis Band Other compounds present in Sample Gas and interfere Bulk gas or another component fully overlaps any of the analysis region. 3
- 5. NO Calibration 5
- 6. Machine Independent Calibration 31 3 30 2.5% 4 29 5 2.0% 28 6 1.5% Easily able to transfer calibrations from one 1.0% instrument to another 0.5% 0.0% 22 12 Instrument to Instrument Variation Based on Ethylene Measurements 21 13 (years 2000 - 2002) 20 14 Demonstration of instrument to instrument variability 6 none of these instruments calibrated for Ethylene
- 7. Analytical Interference Removal Regions Change with Concentration – Change Analysis Regions Higher resolution allows analysis in the presence of the interference (usually H20) Spectral Interference Correction (H2O) – Mask Interferences (‘picket fencing’) 7
- 8. Different Regions for Different Concentrations 20% CO2 8% CO 100 ppm CO 8
- 9. Low Resolution (2.0 cm-1) Sample H2O NO Example of catalyst performance evaluation Figure used with permission from Johnson Matthey plc, Wayne, PA 9
- 10. High Resolution (0.5 cm-1) Sample H2O NO Example of catalyst performance evaluation Figure used with permission from Johnson Matthey plc, Wayne, PA 10
- 11. Removing H2O Interference 11
- 12. Removing H2O NO Water Sample 150ppm NO in 35% H2O (white) 35% H2O (red) Sample minus H2O (white) NO calibration (green) 12
- 13. No interference of water High sensitivity Low detection limits No artificial bias even in very high water (up to 40%) 13
- 14. Reduction of Sampling System Interferences Sample Line Temperature Sample Pressure Reactive Components Material Selection 14
- 15. FT-IR Sampling System Heated Probe with filtering – Metal or Glass – <0.1 um recommended (must keep particulate low) Heated Sampling Line – MKS recommends SS not Teflon for most Apps – Minimum length as possible – Maintain Temp – 191 C normally – Maintain Pressure – 1.0 Atm (+/- 5% recommended) Sampling Pump – Before or After FT-IR Gas Analyzer Before be careful about contamination or sample loss After be careful not to let pressure go to low – Additional Filtering Possible if before 15
- 16. Field Deployable FTIR Heated Lines Sampling System Heated Probe Filter Box Stack On-Off Valve Rotometer FTIR Gas Analyzer Cylinder Spike Standard with SF6 Tracer Spike Recovery: cal gas 10% total flow Calibrated Gas Run: cal gas 7 lpm if pump pulls 5 lpm 16
- 17. Portland Cement Plants Continuous Emission Monitoring National Emission Standards for Hazardous Air Pollutants From the Portland Cement Manufacturing Industry (40 CFR 63 SUBPART LLL) – Maximum Achievable Control Technology (MACT) Standards First EPA mandated National Limits to Reduce Mercury and Other Toxic Emissions from Cement Plants EPA issued final Portland Cement MACT in September 2010 Components required – NOx, SO2, HCl, CO, CO2, PM, THC, mercury 17
- 18. HCl Measurements with FTIR EPA Method 321 – “Measurement of Gaseous Hydrogen Chloride Emissions At Portland Cement Kilns by Fourier Transform Infrared (FTIR) Spectroscopy” – Isolated sample analysis EPA Method 7E – “Determination of Nitrogen Oxides Emissions From Stationary Sources (Instrumental Analyzer Procedure)” – Describes general measurements requirements for all gases when using a continuous instrumental analyzer 18
- 19. HCl Measurements with FTIR Sample (white) with 5 ppm HCl and 12% water (red) H2O subtraction HCl peaks clearly visible after H2O subtraction 19
- 20. HCl Measurements with FTIR (2) HCl calibration peaks (red and green) HCl subtraction After HCl subtraction, only noise left 20
- 21. No Interference of Water High Sensitivity H2O steps up to 40% Low detection limits No artificial bias even in very high water (up to 40%) 21
- 22. MG2030 CEM Ranges and Detection Limits Component ppm mg/m3 CH4 0 - 21 0 - 15 CH4 0 - 70 0 - 50 CO 0 - 60 0 - 75 CO 0 - 120 0 - 150 Component Detection limit CO 0 - 1200 0 - 1500 CH4 0.3 ppm CO2 25% 25% CO 0.5 ppm H2O 40% 40% CO2 0.025% HCl 0-9 0 - 15 HCl 0 - 55 0 - 90 H2O 0.25% HCl 0 - 123 0 - 200 HCl 0.20 ppm HF 0 - 11 0 - 10 HF 0.25 ppm N2O 0 - 26 0 - 50 N2O 0.1 ppm N2O 0 - 51 0 - 100 N2O 0 - 255 0 - 500 NH3 0.35 ppm NH3 0 - 13 0 - 10 NO 0.5 ppm NH3 0 - 99 0 - 75 NO2 0.4 ppm NO 0 - 149 0 - 200 SO2 0.6 ppm NO 0 - 299 0 - 400 NO 0 - 1119 0 - 1500 NO2 0 - 24 0 - 50 NO2 0 - 49 0 - 100 NO2 0 - 488 0 - 1000 SO2 0 - 26 0 - 75 SO2 0 - 105 0 - 300 SO2 0 - 699 0 - 2000 22
- 23. Solution for Compliance of Portland Cement Plants FTIR designed for Continuous Emission Monitoring – Thermoelectric detector, no need of liquid N2 HCl detection limit of 0.2 ppm – Calculated as 3-sigma in 25% H2O Typical Gases and Ranges – CH4 0-21 ppm 0-70 ppm – CO 0-60 ppm 0-1200 ppm – CO2 0-25% (soon to 40%) – NOx 0-149 ppm 0-300 ppm – SO2 0-26 ppm 0-699 ppm – H2O 0-40% – HCl 0-9 ppm 0-55 ppm FTIR associated with FID (THC), PM and mercury sensors for complete solution 23
- 24. Why MKS Over Competitors
- 25. CEM FTIR Advantages – Multiple species – one instrument SO2, NH3, NO, HCl, HF, CO, CO2, H2O, and VOCs – Analyze components in high CO2 and H2O – Direct analysis – no chemical conversion or “fudge factors” – Analysis method minimizes interferents – Flexibility in Changing in Method Customer can easily modify 25
- 26. WHY MKS? Fastest Acquisition with High Resolution (0.5cm-1) Smallest gas cell volume with long pathlength – 200 mL for 5.11m Path Process Instrument – Not a Lab system converted to Process – Engineered for Process Environment – Gas Cell integrated heaters and pressure controller Provide Method Development as well as Customer Support 26