Iron bromide mercury removal compound liquid and method for removing mercury of flue gas by use of same

Abstract

The invention relates to an iron bromide mercury removal compound liquid and a method for removing mercury of flue gas by use of the same. The compound liquid is an iron bromide mercury removal compound liquid which is prepared by taking iron chloride and calcium bromide as main active raw material components and adding hydrogen peroxide with certain concentration, wherein the molar ratio of iron chloride to calcium bromide is 2:3, the mass concentration of iron chloride is 1-10%, and the mass concentration of hydrogen peroxide is 0.1-2.0%. The method for removing mercury of flue gas by use of the iron bromide mercury removal compound liquid comprises the following steps of: uniformly spraying the iron bromide mercury removal compound liquid into the coal-fired flue gas according to certain proportion; generating active bromine atoms or molecules through the oxidation effect of iron ions and hydrogen peroxide on the bromine ions, and converting zero-valence mercury in the flue gas into bivalence mercury by use of the active bromine atoms or molecules; and finally, synchronously absorbing and removing the bivalence mercury and residual iron bromide compound liquid in the flue gas by a wet desulfurization device to achieve an aim of removing mercury in the flue gas. Compared with the prior art, the method provided by the invention can improve the oxidation efficiency of zero-valance mercury in the coal-fired flue gas, avoid secondary pollution and save cost.

Description

technical field [0001] The invention relates to a control technology for mercury emission in coal-fired flue gas in the technical field of environmental protection, in particular to a mercury-removing compound liquid of ferric bromide and a method for removing mercury from flue gas by using the same. Background technique [0002] Because mercury has strong toxicity, accumulation, and stays in the atmosphere for a long time, it is obviously harmful to human health and the living environment. Mercury is one of the most volatile heavy metal elements in coal combustion. Due to the huge annual global consumption of coal combustion, coal combustion flue gas has become the main source of anthropogenic mercury emissions. As one of the countries with the most serious mercury pollution in the world, my country has begun to pay attention to the emission control of mercury pollution in coal-fired flue gas, and has achieved certain results in the research of coordinated removal of mercur...

AI Technical Summary

Problems solved by technology

Patent CA2418578 directly sprays halides and other salts into hot flue gas to enhance the conversion of zero-valent mercury, but the oxidation activity of such substances is low, and they must be used in combination with other adsorbents to achieve better results; patent US2008107579 proposes Adding salts such as chlorides to coal to improve the conversion of zero-valent mercury in flue gas, but this method will accelerate the corrosion of boiler furnace and heat exchange surfaces

[0005] The chlorine-containing or bromine-containing salts used in the above process have weak oxidation activity to zero-valent mercury, which leads to an increase in the dosage of chlorine or bromine, which not only causes waste of raw materials, but also may cause secondary pollution