钢铁工业烧结过程二噁英的产生机理与减排研究进展

Formation Mechanism and Emission Reduction of PCDD/Fs in Iron Ore Sintering

铁矿石烧结是目前一个重要的二噁英(PCDD/Fs)产生工业源,烧结过程二噁英的生成机理复杂,主要由前驱体化合物经有机化合反应生成和碳、氢、氧和氯等元素通过"从头合成"生成,其中以"从头合成"为主,二噁英在烧结机上不仅在干燥带中产生,而且在燃烧带和烧结带的排烟道中也产生。烧结过程二噁英的减排主要方法分为源头控制、过程与操作控制以及末端治理3种,源头控制是烧结过程抑制二噁英产生的最佳选择,现行工艺往往选择末端治理。烧结烟气成分复杂,单一的二噁英减排技术减排幅度未必奏效,而且投资比较大。针对烧结工序的技术特点和烧结烟气的特征,烧结污染物协同减排是烧结工序节能减排的最佳途径,如烧结烟气循环不但可以减少二噁英产生,还可以同时减少NOx和粉尘量的排放,这是今后烧结协同减排发展的一个方向。

Iron ore sintering is an important industrial source of dioxin （PCDD/Fs）, and the mechanism of generating dioxins in sintering process is very complex. Reaction by a precursor compound of an organic compound and De novo are two main ways, and De novo is the main way. Dioxins in the sintering machine are produced not only in the dry zone, but also produced in exhaust flue after the sinter zone and the combustion zone. There are three ways to reduce emissions of dioxins： source control, process control and operation, and treatment in the end. Source control is the best choice for the in- hibition of dioxin, and treatment in the end is often chosen in the current process. Single dioxin abatement technologies may not be feasible for the complexity of sintering flue gas composition, and the investment is relatively large. For the technical characteristics of the sintering process and flue gas, the best way is synergistic emission reduction. Circulating sintering flue gas can reduce dioxins, Nox and dust content, etc. So it will be an important development direction.