Flue gas concerted catalytic denitration and demercuration technology

Abstract

The invention provides a flue gas concerted catalytic denitration and demercuration technology. The technology realizes simultaneous removal of NOx and Hg<0> without arranging a flue gas purifying device, so the reconstruction cost of present apparatuses is saved, and pollution to atmosphere is reduced, thereby the technology has strong industrial application values. The technology comprises the following steps: 1, injecting ammonia gas fully mixed with air to a boiler flue gas through the nozzle of an ammonia injection grating, fully mixing, and converting NOx in the flue gas into N2 under the action of an upper portion honeycomb Ce-Cu-V-W-TiO2 composite catalyst; 2, introducing treated flue gas obtained in step 2, and carrying out catalytic oxidation on a tiny amount of O2 and HCl and Hg<0> under the action of a lower portion honeycomb Ce-Cu-V-W-TiO2 composite catalyst to generate HgCl2; and 3, allowing a treated gas obtained in step 2 to enter the operating unit of a desulfurization tower, capturing gaseous divalent mercury having high solubility in water by a wet washing system to remove the gaseous divalent mercury, and treating sulfur-containing compounds in the flue gas to recover elemental sulfur.

Description

technical field [0001] The invention relates to the technical field of waste flue gas treatment technology, in particular to a flue gas synergistic catalytic denitrification and mercury removal process. Background technique [0002] With the rapid growth of coal utilization, SO emissions from coal-fired boiler flue gas x , NO x And pollutants such as heavy metal Hg remain high, seriously affecting the ecological environment and human health. where SO x and NO x The environmental pollution caused by acid rain and photochemical smog, and the pollution control of heavy metal mercury is also increasingly on the agenda (the emission standard of air pollutants in thermal power plants requires coal-fired boilers to control the emission of mercury and its compounds from January 1, 2015. at 0.03mg / m 3 the following). Therefore, while controlling SO 2 , NO x and mercury emission requirements are more urgent. [0003] Mercury exists in the form of elemental mercury (Hg 0 ), d...

AI Technical Summary

Problems solved by technology

The process mainly uses a large amount of ammonia and lye, resulting in a large amount of wastewater pollution

[0007] Chinese patent CN103203160A discloses a combined flue gas desulfurization, denitrification and mercury removal device and its method, including two combined desulfurization, denitrification and mercury removal reactors, using ammonia injection and activated coke adsorption processes to improve the efficiency of desulfurization, denitrification and mercury removal, but It involves the regeneration of active coke and the reprocessing of desorbed impurities, causing secondary pollution

[0008] Chinese patent CN103394274A discloses a flue gas combined denitrification, demercury and desulfurization system device and its method, including a desulfurization absorption tower and a gypsum dehydrator connected to the desulfurization absorption tower and used to dehydrate the gypsum slurry at the bottom of the desulfurization absorption tower, and also includes A denitrification device for simultaneous processing of catalytic denitrification and oxidation of zero-valent mercury to divalent mercury ions, a flue gas pipeline connecting the denitrification device with the desulfurization absorption tower, and the gypsum dehydrator to dehydrate the gypsum The final desulfurization gypsum wastewater containing chloride ions is transported into the waste water pipeline of the flue gas pipeline. This system needs to spray water containing chloride ions in the flue gas pipeline, which is corrosive to the device and increases equipment costs.

In addition, the process produces a large amount of waste water, which is likely to cause secondary pollution

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