Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China.
Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China.
Environ Sci Technol. 2022 Mar 15;56(6):3544-3551. doi: 10.1021/acs.est.1c07708. Epub 2022 Mar 3.
Flue gas desulfurization (FGD) scrubbers capture selenium in coal-fired power plants, leading to a high concentration of selenium in the slurry. This research proves that SO is preferentially oxidized compared to SeO by SO. With the increase in the oxidation-reduction potential (ORP) caused by SO addition, the conversion rate of SO increased and the size of gypsum grains grew from 31.2 to 34.6 μm. SeO migrates into gypsum grains during the growth of CaSO·2HO, leading to selenium fixation in gypsum. In a field study of a 350 MW unit, the ORP increased from 142 to 450 mV when NaSO was fed into the FGD slurry. With the addition of the oxidant, 65.1% of selenium in the liquid phase migrated into gypsum. The concentration of selenium in the leachate of gypsum after oxidant addition decreased by 68.0%. A 2.34% increase in the selenium removal rate was observed in the scrubber. This study focuses on the migration and conversion of selenium in an actual FGD slurry via a field test. The results found in the 350 MW unit are consistent with laboratory results. The change in ORP has been proven to be effective in adjusting the selenium distribution in the FGD slurry.
烟气脱硫 (FGD) 洗涤器在燃煤电厂中捕获硒，导致浆液中硒的浓度很高。本研究证明，SO 优先于 SeO 被 SO 氧化。随着 SO 添加引起的氧化还原电位 (ORP) 的增加，SO 的转化率增加，石膏晶粒的尺寸从 31.2 增长到 34.6 μm。SeO 在 CaSO·2HO 生长过程中迁移到石膏晶粒中，导致硒在石膏中固定。在 350 MW 机组的现场研究中，当向 FGD 浆液中添加 NaSO 时，ORP 从 142 增加到 450 mV。添加氧化剂后，液相中 65.1%的硒迁移到石膏中。添加氧化剂后，石膏浸出液中硒的浓度降低了 68.0%。在洗涤器中观察到硒去除率提高了 2.34%。本研究通过现场测试重点研究了实际 FGD 浆液中硒的迁移和转化。在 350 MW 机组中得到的结果与实验室结果一致。ORP 的变化已被证明可有效调节 FGD 浆液中硒的分布。
