Investigation on mercury reemission from limestone-gypsum wet flue gas desulfurization slurry.

Chuanmin Chen,Yang Gao,Songtao Liu,Yongchao Liu

doi:10.1155/2014/581724

Chuanmin Chen, Yang Gao + Show 2 more

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https://doi.org/10.1155/2014/581724

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Abstract

Secondary atmospheric pollutions may result from wet flue gas desulfurization (WFGD) systems caused by the reduction of Hg2+ to Hg0 and lead to a damping of the cobenefit mercury removal efficiency by WFGD systems. The experiment on Hg0 reemission from limestone-gypsum WFGD slurry was carried out by changing the operating conditions such as the pH, temperature, Cl− concentrations, and oxygen concentrations. The partitioning behavior of mercury in the solid and liquid byproducts was also discussed. The experimental results indicated that the Hg0 reemission rate from WFGD slurry increased as the operational temperatures and pH values increased. The Hg0 reemission rates decreased as the O2 concentration of flue gas and Cl− concentration of WFGD slurry increased. The concentrations of O2 in flue gas have an evident effect on the mercury retention in the solid byproducts. The temperature and Cl− concentration have a slight effect on the mercury partitioning in the byproducts. No evident relation was found between mercury retention in the solid byproducts and the pH. The present findings could be valuable for industrial application of characterizing and optimizing mercury control in wet FGD systems.

Highlights

Mercury and its compounds are highly toxic species which have a considerable impact on human health
The experimental results indicated that the Hg0 reemission rate from wet flue gas desulfurization (WFGD) slurry increased as the operational temperatures and pH values increased
The Hg0 reemission rates decreased as the O2 concentration of flue gas and Cl− concentration of WFGD slurry increased

Summary

Introduction

Mercury and its compounds are highly toxic species which have a considerable impact on human health. Whereas HgP is retained in the electrostatic precipitators or bag filters, both Hg2+ and Hg0 species from the flue gas are emitted to the atmosphere in power plants without undergoing any postcombustion processes to reduce emissions. Wet flue gas desulfurization (WFGD) systems installed in coal fired power plants to control SO2 emissions have been used to decrease mercury emissions [3,4,5,6,7]. In such systems, SO2 usually reacts with the limestone slurry to produce insoluble gypsum

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