An Improved Method for Optimizing Detection Bands of Marine Exhaust SO2 Concentration in Ultraviolet Dual-Band Measurements Based on Signal-to-noise Ratio

SO2 emitted from ship exhaust can cause serious air pollution. Ultraviolet (UV) imaging detection technology is considered to be a simple and effective technique for detecting SO2 concentration in ship exhaust gas. To predict the concentration of SO2 emitted by ships more accurately, in this paper, a simulation and analysis model of UV dual-band imaging detection of ship exhaust gas is established by considering different types and concentrations of ship exhaust gas, natural background radiation intensity, transmittance of the filter used, and quantum efficiency of the detector. The results of wavelength optimization show that for zenith angles 10°, 20°, 30°, 40°, 50°, 60°, 70°, and 80°, the corresponding optimal dual band positions are (301, 303), (305, 307), (302, 307), (307, 309), (312, 315), (316, 317), (321, 323), and (331, 332) nm, respectively. The sulfur–carbon ratio was calculated based on the SO2 concentration obtained and CO2 concentration collected and from these measurements the sulfur content in the marine oil used was calculated. The results show that the sulfur content can be accurately estimated on the basis of the sulfur–carbon ratio in favorable background radiation conditions.