Robust optical measurement of water vapor in steel-making process

Based on tunable diode laser spectroscopy (TDLS), we develop a simple and efficient humidity monitoring scheme to improve reliability of measurement under randomly changing transmission condition. This measurement scheme can detect the humidity of a monitored system in either high or low scattering condition such as powder coal fired furnace in steel-making process. Distributed feed-back (DFB) diode laser is used to evaluate the relative and absolute humidity by making direct absorption measurement near 938 nm region where 2nu1 + nu3 water vapor transition band exists. This system gives reliable measurement results under either high or low scattering condition.

[1]  David E. Cooper,et al.  Tunable diode laser frequency modulation spectroscopy through an optical fiber: High‐sensitivity detection of water vapor , 1990 .

[2]  J. Hodges,et al.  Wavelength-modulation laser hygrometer for ultrasensitive detection of water vapor in semiconductor gases. , 2001, Applied optics.

[3]  Sang Woo Kim,et al.  Detection of line defects in steel billets using undecimated wavelet transform , 2008, 2008 International Conference on Control, Automation and Systems.

[4]  R. Stephenson.  A and V , 1962, The British journal of ophthalmology.

[5]  Ronald K. Hanson,et al.  Wavelength modulation absorption spectroscopy with 2 f detection using multiplexed diode lasers for rapid temperature measurements in gaseous flows , 2004 .

[6]  G. Herzberg,et al.  Molecular spectra and molecular structure. Vol.2: Infrared and Raman spectra of polyatomic molecules , 1945 .

[7]  Renato Lemus,et al.  Vibrational excitations in H2O in the framework of a local model , 2004 .

[8]  T. Fernholz,et al.  In-situ monitoring of water vapour and gas temperature in a coal fired power-plant using Near-Infrared Diode Lasers , 2001 .

[9]  Gang Li,et al.  The HITRAN 2008 molecular spectroscopic database , 2005 .

[10]  M. P. Arroyo,et al.  Absorption measurements of water-vapor concentration, temperature, and line-shape parameters using a tunable InGaAsP diode laser. , 1993, Applied optics.

[11]  Wavelength Modulation Absorption Spectroscopy with 2f Detection for Combustion Temperature Measurements Using Multiplexed Near-Infrared Diode Lasers , 2004 .

[12]  G. Herzberg,et al.  Molecular Spectra and Molecular Structure , 1992 .