Fig. 1. Radiation model of industrial cement-kiln

Fig. 2. Averaged spectrum

Fig. 3. Transmittance spectrum of CO2

Fig. 4. Schematic of FTIR system

Fig. 5. Interference signal

Fig. 6. Spectrogram

Fig. 7. Schematic of traditional data processing method

Fig. 8. Averaged results of signal containing turbulence noise in the same group obtained by different data processing methods

Fig. 9. Comparison of spectra ranging from 2100 cm-1 to 2200 cm-1

Fig. 10. Schematic of proposed data processing method

Fig. 11. Absorption spectrum of CO at 1200 ℃

Fig. 12. Corrected and uncorrected transmittance spectra at 2203 cm-1

Fig. 13. Nonlinear least square fitting between calibration spectrum and measurement spectrum of CO

Fig. 14. Residual spectrum after fitting

Fig. 15. CO concentration error under different temperature errors

Fig. 16. Averaged spectrum data of 16 times in industrial site

Fig. 17. On-line monitoring results of gas concentration in cement-kiln