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TDLTech Presentation 14

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Tunable Diode Laser technical presentation

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TDLTech Presentation 14

  1. 1. © TDL Sensors Ltd 2012 Tunable Laser Gas Monitoring
  2. 2. © TDL Sensors Ltd 2012  Very high sensitivity - ppt, ppb, ppm concentrations  Measure the gas you want without interference from other gases  Large dynamic range - 5 orders of magnitude  Absolute measurements – no drift, no calibration, inherently linear  Real-time (10 Hz or faster response)  Very low maintenance  Does not wear out Advantages of laser based gas analysers: Tunable Laser Gas Monitoring
  3. 3. © TDL Sensors Ltd 2012 Based upon high-resolution laser spectroscopy Tunable Laser Gas Monitoring
  4. 4. © TDL Sensors Ltd 2012 Tunable Laser Gas Monitoring Mid IRNear IRUV-Vis Visible
  5. 5. © TDL Sensors Ltd 2012 0.7-2.7 µm Laser diodes, VCSELs 3-5 µm 4.2->12 µm DFGs QCLs Tunable Laser Gas Monitoring We use the IR spectral region for gas measurements Tunable lasers available within this region
  6. 6. © TDL Sensors Ltd 2012 Tunable Laser Gas Monitoring NIR Mid-IR Each gas absorbs light in a characteristic way. Hydrogen Fluoride (HF) Carbon Dioxide (CO2)Nitric Oxide (NO)Ammonia (NH3)Carbon Monoxide (CO)Methane (CH4)Water (H2O) This means that each gas has a unique spectrum or “fingerprint”.
  7. 7. © TDL Sensors Ltd 2012 Tunable Laser Gas Monitoring Tunable laser Photodetector I0 Beer - Lambert Law:  L I I T )(exp)( 0         Absorption coefficient PathlengthTransmission  I I0 Laser frequency tuned I Transmission Signal out Gas Gas in Gas out Measurement cell L
  8. 8. © TDL Sensors Ltd 2012 Laser wavelength is tuned rapidly – no photodetector filters Spectra are recorded 1000s of times per second Not affected by particulate attenuation or changes in mirror reflectivity Full spectrum analysis performed Powerful pattern recognition signal processing methods used Absolute concentration measured – no drifting like other techniques Tunable Laser Gas Monitoring
  9. 9. © TDL Sensors Ltd 2012 Full spectrum analysis performed Powerful pattern recognition signal processing methods used Absolute concentration measured – no drifting like other techniques Tunable Laser Gas Monitoring
  10. 10. © TDL Sensors Ltd 2012 Tunable Laser Gas Monitoring Extractive gas analyser multipass optical cell
  11. 11. © TDL Sensors Ltd 2012 Very long pathlengths can be achieved using a laser - 7.6 m standard - 70 m enhanced
  12. 12. © TDL Sensors Ltd 2012 Sample gas stream is often measured at atmospheric pressure However, TDL can also measure at reduced sample pressure
  13. 13. © TDL Sensors Ltd 2012 Advantage of measuring at reduced sample pressure
  14. 14. © TDL Sensors Ltd 2012 Reduced sample pressure advantages • Very specific measurement(s) • Multi-gas measurements with one laser • Enhanced stability • No liquid phase water • No gas sample stream drying required
  15. 15. © TDL Sensors Ltd 2012 Example: HCl 1 ppm H2O 30 % Vol emissions from a stack Reduced sample pressure advantages
  16. 16. © TDL Sensors Ltd 2012 1010 mbarA Pathlength = 760 cm, Temperature = 360 K Reduced sample pressure advantages -20 -10 0 +10
  17. 17. © TDL Sensors Ltd 2012 Peak widths narrow Reduced sample pressure advantages -20 -10 0 +10 100 mbarA Pathlength = 760 cm, Temperature = 360 K
  18. 18. © TDL Sensors Ltd 2012 Reduced sample pressure advantages -20 -10 0 +10 1010 mbarA Pathlength = 760 cm, Temperature = 360 K
  19. 19. © TDL Sensors Ltd 2012 Reduced sample pressure advantages -20 -10 0 +10 100 mbarA Pathlength = 760 cm, Temperature = 360 K
  20. 20. © TDL Sensors Ltd 2012 Reduced sample pressure advantages -2 -1 0 +1 +2 1010 mbarA Pathlength = 760 cm, Temperature = 360 K
  21. 21. © TDL Sensors Ltd 2012 Isolated HCl peak - even in the presence of high humidity -2 -1 0 +1 +2 100 mbarA Reduced sample pressure advantages Pathlength = 760 cm, Temperature = 360 K
  22. 22. © TDL Sensors Ltd 2012 Isolated HCl peak Can also access H2O peaks to report dry gas conc Reduced sample pressure advantages -2 -1 0 +1 +2 100 mbarA Pathlength = 760 cm, Temperature = 360 K
  23. 23. © TDL Sensors Ltd 2012
  24. 24. © TDL Sensors Ltd 2012 Technology Contact TDL Sensors Ltd 48 Grafton Street Manchester M13 9XX United Kingdom Tel: +44 (0)161 606 7289 info@tdlsensors.co.uk www.tdlsensors.co.uk

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