| Summary: | 博士 === 國立成功大學 === 環境工程學系 === 88 === The objectives of this study are to investigate the performance, reaction kinetics, and economic evaluation of NOX/SO2 wet scrubbing with NaClO2 solutions in a single spray column or twin spray columns. The operating parameters include the NOX concentration, SO2 concentration, NaClO2 concentration, initial pH value, operating temperature, retention time, NaOH concentration, and liquid flow rate.
As the results indicated, the NO conversion and NOX removal efficiency for combined NOX/SO2 tests were much higher than that of individual NOX removal tests in the range of this study. It reveals that combined NOX/SO2 wet scrubbing with NaClO2 solutions in conventional FGD system is worth to develop. For the twin spray columns, the NOX removal efficiency in the second column was not good enough as expected. The results also supply the reaction order, reaction rate constant, and activation energy.
The analysis results of liquid components by IC and UV indicate that the species formed in the liquid for NOX absorbed into solutions are nitrite and nitrate. The ratio of chloride and ClO2 gas formed from NaClO2 varies with the pH value of absorbing liquids.
The empirical correlation of NO conversion/NOX removal efficiency and operating parameters were calculated by SAS statistic program. The equations obtained are shown as below:
NO conversion for individual NOX removal tests in a single spray column:
NO Conversion = 3321.09×([NO])-0.1897×(RT)1.2427×([NaClO2])1.0544×(Temp.)0.3123×(pH)-2.2240
NOX removal efficiency for individual NOX removal tests in a single spray column:
NOX Removal Efficiency = 275.90×([NOX])0.3716×(RT)1.2032×([NaClO2])1.0404×(Temp.)0.2424×(pH)-1.5977
The verification of above equations was performed with the data of twin spray columns tests. For NO conversion, the calculated values are close to the experimental data. However, the relative errors between the calculated values and experimental data are slightly higher for NOX removal efficiency.
The cost per ton of NOX removal with NaClO2 solution is NT$ 105,000 in the new installed plant, but is only about NT$ 7,200 for existing FGD system with simple retrofit. It should benefit for developing this process in the future.
|
|---|
