Simultaneous Removal of SO2 and NOx by Calcium Hydroxide at Low Temperature: Effect of SO2 Absorption on NO2 Removal
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- 作者：Guoqing Chen ; Jihui Gao ; Jianmin Gao ; Qian Du ; Xiaolin Fu ; Yijun Yin ; Yukun Qin
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2010
- 出版时间：December 1, 2010
- 年：2010
- 卷：49
- 期：23
- 页码：12140-12147
- 全文大小：397K
- 年卷期：v.49,no.23(December 1, 2010)
- ISSN：1520-5045
文摘
A fixed reactor was employed to investigate the influence of SO2 absorption process on NO2 removal by Ca(OH)2 under low-temperature and humid circumstance. The step experiments and pretreatment experiments were carried out to investigate the effect of the desulfurization product CaSO3 on NO2 removal. The roles of gas components (O2, H2O) and reaction temperature in SO2 enhancing NO2 removal were discussed by comparing their influences on NO2 removal in and without the presence of SO2. It is interesting to observe that NOx removal first increases and then decreases with the increase of SO2 concentration. The presence of SO2 in the flue gas was found to restrain NO release and enhance NO2 removal. SO2 removal product CaSO3 did provide an additional reaction path for NO2 removal, but the reaction rate of NO2 and CaSO3 was lower than that of Ca(OH)2 due to the lower solubility of CaSO3. The enhancement effect of SO2 on NO2 removal can be explained by the presence of SO32− and HSO3− ions derived from the hydrolysis of SO2 in the water layer. HSO3− and SO32− reacted with NO2 to form sulfate, which was detected in the spent absorbent by X-ray diffraction. The higher relative humidity can accelerate the hydrolysis of SO2 and the dissolution of Ca(OH)2, which are in favor of NO2 removal. However, the oxidization of SO32− to SO42− by O2 lowers NO2 removal. Reaction temperature has negligible influence on the enhancement of NOx removal by the presence of SO2.