Abstract
In China, sintering flue gas has become the most important source of air pollution rather than burning coal-fired flue gas.The emission characteristics and removal efficiencies of various gaseous pollutants were studiedon a 180 m2 sintering equipped with a semi-dry oxidative desulfurization and denitrification system in Tangshang, Hebei province. The emission concentrations of particulate matter, fluoride,NOX and SO2were measured in the flue gas whilepolychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) were tested in both flue gas and dust ash at 100% and 60% loadconditions. The collections and analyses ofpollutantswere used by smoke sampler, TESTO350 and dioxin sampleraccording to national standards of China. The results shown that the average emission concentration of particulate matter, fluoride, NOX and SO2 in the inlet of the flue gas purification system were 47.4 mg/m3, 0.12 mg/m3, 150 mg/m3 and 521 mg/m3 while the emission concentrations in the outlet were 1.2 mg/m3, 0.07 mg/m3, 24 mg/m3 and 20 mg/m3,respectively. Through the flue gas purification system, the PCDD/Fs concentrations were reduced from 23.12 ng/m3to 1.14 ng/m3at100% load and from 12.25 ng/m3 to 0.84 ng/m3at60% load. The PCDD/Fs concentrations in the dust ash were about 178.56~197.21 ng/kg. Thedesulfurization and denitrification system significant reduced effect on the emission of particulate matter, fluoride, NOX, SO2 and PCDD/Fs with the value 97.5%, 41.7%, 84.0%, 96.2% and 95.1% at 100% load, respectively.The removal affects increases along the chlorination degree of PCDD/Fs. Meanwhile,the different load influenced the emission concentrations and removal rates of PCDD/Fs in the flue gas, the removal effects increases as the load increases. Although the desulfurization and denitrification system has good removal effects on various pollutants, the dioxins were enriched in the dust ashso as to cause secondary pollution.
Highlights
Nowadays, steel industry has become an important pillar industry of the national economy
In this study we explored the effect of the oxidative desulfurization and denitrification unit on the removal of particulate matter, fluoride, NOX, SO2 and 2,3,7,8-substituted PCDD/Fs in flue gas and the 2,3,7,8-substituted PCDD/Fs content in the ash
This study focused on the removal effects and emission distribution characteristics of particulate matter, SO2, NOX, fluoride and dioxins in the sintering flue gas with an oxidative desulfurization and denitrification system
Summary
Steel industry has become an important pillar industry of the national economy. The flue gas of the sintering machine head is the main source of atmospheric pollutants in the steel plant. The pollutants emitted by the sintering machine head mainly include particulate matter, SO2, NOX, fluoride, and dioxins [1], especially dioxin emissions [2] account for more than one-third of the entire plant, and the sintering head flue gas is the most important source of dioxin emissions in China except for waste incineration. In China, it has a comprehensive study on the emission characteristics of atmospheric pollutants from coal-fired power plants and waste incineration plant [3,4,5,6], but the research on the emission characteristics of sintering heads has just started [4,7]. Compared with foreign studies [8,9], there is a lack of basic data on the emission characteristics of various pollutants in steel plants, as well as monitoring results under different operating loads [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25]
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