Abstract Limestone–gypsum wet flue gas desulfurization (WFGD) is the most effective desulfurization technique. However, to achieve ultralow SO2 emissions, the efficiency of WFGD should be improved and its energy consumption reduced. To address these aims, a technology of coupling WFGD with condensation desulfurization using a condensing heat exchanger (CHE) was proposed in this study. The results show that, as the WFGD approaches the limiting desulfurization efficiency, a small increase in the efficiency may cause a high energy consumption. However, the energy consumption can be reduced significantly through the synergistic absorption of SO2 during the wet flue gas condensation. The synergistic absorption efficiency is affected by the SO2 concentration at the inlet of the CHE, flue gas flow, and the amplitude and rate of temperature drop. Injecting Ca(OH)2 into the flue gas during wet flue gas condensation can form dispersive heterogeneous cores of Ca(OH)2 in the flue gas, thereby enhancing SO2 mass transfer and improving the desulfurization efficiency considerably. The increased amount of Ca(OH)2 is small, and the unreacted Ca(OH)2 can be fully utilized by collecting the condensed solution and returning it to the WFGD system. When the coupling desulfurization technology is applied to achieve ultralow SO2 emissions, at inlet SO2 concentrations of 2000 and 4000 mg/Nm3, the circulating pump power consumption decreases by 351–449 kW and 1661.5–2125.5 kW for 300- and 1000-MW units, respectively, demonstrating the significant energy-saving potential of the coupling desulfurization technology.

中文翻译：

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湿法脱硫与冷凝脱硫耦合节能增效

摘要 石灰石-石膏湿法烟气脱硫（WFGD）是最有效的脱硫技术。然而，要实现超低 SO2 排放，需要提高 WFGD 的效率并降低其能耗。为了解决这些问题，本研究提出了一种将 WFGD 与使用冷凝换热器 (CHE) 的冷凝脱硫相结合的技术。结果表明，随着WFGD接近极限脱硫效率，效率的小幅提高可能会导致高能耗。但是，通过湿法烟气冷凝过程中SO2的协同吸收，可以显着降低能耗。协同吸收效率受CHE入口SO2浓度、烟气流量、温降幅度和速率的影响。在湿法烟气冷凝过程中向烟气中注入Ca(OH)2，可以在烟气中形成分散的Ca(OH)2非均质核，从而增强SO2传质，显着提高脱硫效率。增加的Ca(OH)2量很小，未反应的Ca(OH)2可以通过收集冷凝液返回WFGD系统得到充分利用。应用耦合脱硫技术实现SO2超低排放，在入口SO2浓度为2000和4000 mg/Nm3时，300-1000-MW机组循环泵耗电量分别降低351-449 kW和1661.5-2125.5 kW，分别展示了耦合脱硫技术的显着节能潜力。