钢铁烧结烟气多污染物的排放特征及控制技术

 监测了钢铁烧结烟气的排放特征,发现SO₂排放浓度沿着烧结机方向呈现机头和机尾低、中部高的特点,二噁英的排放浓度与烟气温度正相关,温度高于250℃时二噁英的排放浓度出现峰值.调研了数十台烧结机的烟气排放特征,表明SO₂排放浓度≤2000 mg/m³的占63%,要求脱硫效率大于90%;>2000 mg/m³的占37%,要求脱硫效率大于96%.NO_x排放浓度≤300 mg/m³的占86%,烟气无需脱硝可直接排放;在300~600 mg/m³之间的占14%,要求脱硝效率大于50%.二噁英排放浓度为1.0~5.0ng TEQ/m³,必须采取控制措施才能达标排放.针对烧结烟气SO₂和二噁英浓度高的特点,论述了基于活性炭吸附的活性炭法,以钙基吸收剂脱硫为主、活性炭(焦)脱二噁英为辅的SDA 法、MEROS 法、IOCFB 法等4 种多污染物协同控制技术及脱除效果.

Emission Characteristics of Multiple Pollutants from Iron- steel Sintering Flue Gas and Review of Control Technologies

The emission characteristics measurement of the iron-steel sintering flue gas shows that the SO₂ concentration is high in the middle of the sintering machine and low at the head and tail parts along the sintering direction. The dioxins concentration has positive a correlation with the flue gas temperature, and reaches a peak value as the temperature above 250℃. The proportion of the SO₂ concentration below 2000 mg/m³ occupies 63%, and the over 2000 mg/m³ occupies 37%. Therefore, the desulfurization efficiency should be higher than 90% and 96%, respectively. The proportion of the NO_x concentration below 300 mg/m³ is 86%, and the flue gas can be discharged directly without treatment. However, the proportion of NO_x concentration between 300 and 600 mg/m³ is 14%, and the denitration efficiency should be higher than 50%. The dioxins concentration between 1.0 and 5.0 ng TEQ/m³ has to be reduced to reach the national standard. According to the emission characteristics of high SO₂ and dioxins concentrations from the sintering flue gas, four kinds of multi-pollutant simultaneous control technologies are reviewed. Activated carbon adsorption belongs to an integrated control technology, while SDA (spray drying adsorption), MEROS (maximized emission reduction of sintering) and IOCFB (inner outer circulating fluidized bed) methods belong to collaborative control technologies based on the SO₂ absorbed by calcium-based sorbents and the dioxins adsorbed by activated carbon. Industrial applications of the four technologies are demonstrated and the removal efficiencies are compared with each other.