Abstract
The absorption characteristics of sulfur dioxide (SO2) and sulfur trioxide (SO3) in the infrared region were measured using a quantum cascade laser and an absorption cell of length 1 m heated to 150°C. The laser was scanned over the wavelength range 6.9-7.4 μm, which included the absorption bands of SO2 and SO3. Measurement results showed that the absorption bands of SO2 and SO3 partially overlapped, with peaks at 7.28 μm and 7.35 μm for SO2 and 7.14 μm and 7.25 μm for SO3. These results showed the possbility of using infrared laser absorption spectroscopy for measurement of sulfur oxides (SOx) in flue gas. For SO3 measurement, infrared absorption spectroscopy was shown to be more suitable than ultraviolet absorption spectroscopy. The absorption characteristics of open air in the same wavelength region showed that the interference due to water vapor must be efficiently removed to perform SOx measurement in flue gas.
