Simultaneous measurements of multiple parameters at elevated temperature using a frequency-division multiplexing...

Area of Science:

• Spectroscopy
• Laser-based sensing technologies
• Gas analysis

Background:

• High-temperature gas sensing is crucial for industrial processes.
• Existing methods often require frequent calibration and are susceptible to fouling.
• Multiplexed laser systems offer potential for simultaneous multi-component analysis.

Purpose of the Study:

• To develop and demonstrate a multiplexed diode-laser sensor system for simultaneous high-temperature gas sensing.
• To utilize wavelength modulation spectroscopy (WMS) with second harmonic detection.
• To enable in-situ measurements without frequent calibration.

Main Methods:

• A frequency-division multiplexing scheme combined two near-infrared diode lasers.
• One laser targeted H2O lines, the other targeted CO2 and CO lines.
• The WMS-1f normalized 2f method was employed for calibration-free measurements.

Main Results:

• Simultaneous measurement of temperature, H2O, CO2, and CO concentrations was achieved.
• Precisions of 1.57% for temperature, 3.87% for H2O, 3.01% for CO2, and 3.58% for CO were demonstrated.
• The system proved effective in a heated static cell, showing robustness against optical disturbances.

Conclusions:

• The developed multiplexed diode-laser sensor system is suitable for high-temperature gas analysis.
• The WMS-1f normalized 2f method effectively corrects for transmission variations.
• This technology holds significant potential for industrial applications requiring accurate, real-time gas monitoring.