抄録
In heavy oil-burning thermal power plants, NH3 injection is frequently used to neutralize SOx in flue gas. In order to ascertain the neutralization effect the concentration of NH3 must be measured in the presence of high concentration of SO2. Ultraviolet absorption spectroscopy in the 200-225 nm wavelength region is the most sensitive method to measure SO2 and NH3. However, as the absorption bands of SO2 and NH3 overlap, accurate determination of the SO2 absorption is needed to detect the absorption due to trace NH3. The nonlinear dependence of the absorption coefficient on the concentration, which appeared for absorption coefficients of α>0.05 cm-1, is taken into account using a third order polynomial approximation in order to accurately determine the SO2 absorption. An analysis procedure based on this approximation was developed. Results showed that NH3 concentrations of about 4 ppm can be detected in the presence of SO2 concentrations of about 1000 ppm.
