Upgrading And Operating Performance Of Ultra Low Emission System For Coal-fired Power Plants Flue Gas

Shijiazhuang,the capital of Hebei Province,has a outstanding atmospheric environment problem in recent years due to the layout of energy structure,industrial structure,special geographical and climatic condition.For this reason,the government of Hebei Province has proposed to promote the environmental protection renovation of air pollutants discharged from coal-fired generating units in service.The emission concentration of air pollutants from public coal-fired generating units below 300,000 kW meet the emission standard of gas,that is,smoke and dust 10 mg?m^-3,sulfur dioxide 35mg?m^-33 and nitrogen oxide 50 mg?m^-3?under the condition of 6%oxygen content?.Based on the above reasons,in order to realize the integrated demonstration of ultra low emission technology,we must upgrade and transform the dust removal system,desulfurization system and denitrification system on the basis of existing treatment facilities.The results showed that:1)With regard to the promotion of dust removal system,we arrange electrostatic precipitator at the top of absorption towers.The smoke dust concentration of final outlet has been reduced from 18 mg?m^-33 to 3 mg?m^-33 which meets the emission standard of 10mg?m^-3.The removal efficiency has reached 83.3%..2)With regard to the upgrading of desulfurization system,two-stage absorption towers are connected on the basis of original desulfurization facilities.The results show that:The optimum pH of the first stage absorber is 5.82.When the inlet SO₂ concentration is 3887.11 mg?m^-3,the outlet is 630.55 mg?m^-33 The removal efficiency is 83.78%.The optimum pH of the secondary absorber is 6.55.When the imported SO₂ concentration is854.26 mg?m^-3,the outlet is 12.43 mg?m^-33 which meets the emission standard of 35 mg?m^-3.The removal efficiency is 98.54%.That circulating slurry pumps are optimized and adjusted under different working conditions.It is best when two small power circulating slurry pumps B and C are operated in the first tower and the second tower starts the G,F and E circulating slurry pumps in turn.3)With regard to the upgrading of denitrification system,the mature technology"low nitrogen burner+SCR device"has been mainly adopted.The outlet NOx concentration which is about 20 mg?m^-33 meets the emission requirement of 50 mg?m^-3.4)The annual emission reduction of nitrogen oxides,soot and sulfur dioxide are929.39,183.26 and 2212.21 tons in Yuhua after the ultra-low emission renovation of the two units,which brings remarkable benefits.