Method for removing heavy metal mercury from low-temperature flue gas by sodium salt method

Abstract

The invention provides a method for removing heavy metal mercury from low-temperature flue gas by a sodium salt method. The method comprises the following steps: taking sodium bicarbonate with strongoxidation action and adsorption action as a flue gas purification and adsorption oxidizing agent bed layer, adsorbing particle-state mercury Hgp in the flue gas by the pores of sodium carbonate with high specific surface area which is generated through thermal decomposition of sodium carbonate, oxidizing element-state mercury Hg0 in the flue gas by a large amount of active oxidizing substances generated through reaction of the sodium bicarbonate and SO2 in the flue gas to be converted into oxidation-state mercury Hg<2+> with high water solubility, enabling the flue gas after oxidation adsorption to enter a spraying tower, performing pyrolysis to adsorb the oxidized sodium bicarbonate and fresh sodium bicarbonate mixed solution spraying liquid and further removing various forms of mercury from the flue gas so as to purify the mercury in the flue gas. The method for removing the heavy metal mercury from the low-temperature flue gas by the sodium salt method, which is provided by the invention, is simple in process, small in investment, low in operating cost and non-corrosive to flue gas purification equipment.

Description

technical field [0001] The invention belongs to the technical field of environmental protection engineering, and relates to a technical method for removing harmful substances in flue gas, and more specifically, relates to a method for removing heavy metal mercury in low-temperature flue gas by a sodium salt method. Background technique [0002] Coal is the fossil fuel with the most abundant reserves in my country. At present, my country still uses fossil energy coal as the main energy source. While coal combustion provides energy for people, it not only produces a large amount of SO x , NO x , Heavy metals in coal, including mercury, can also cause heavy metal pollution, causing great harm to ecosystems and humans. The average content of heavy metal mercury in coal is 0.15mg / kg. According to statistics, in 2010 China's mercury emissions caused by coal burning reached 253 tons. Mercury pollution caused by coal burning is a common problem and challenge faced by mankind, an...

AI Technical Summary

Problems solved by technology

[0008] The technical problem to be solved by the present invention is to overcome the problem of insufficient activity of the heavy metal mercury adsorbed oxidant in flue gas under low temperature conditions, and to find an adsorbed oxidant with good adsorption activity under low temperature conditions, which can efficiently promote the adsorption of mercury in coal-fired flue gas. Elemental Mercury Hg 0 into the oxidized state of mercury Hg 2+ , to resolve elemental mercury Hg 0 Difficult to be captured by traditional technologies. Based on the found adsorption oxidant, a sodium salt method is provided to remove heavy metal mercury in low-temperature flue gas. This method is simple, low investment, low operating cost, and has no corrosion to flue gas purification equipment.