高炉处理烧结烟气脱硫脱硝理论分析

对利用高炉处理烧结烟气同时脱硫脱硝脱二噁英技术的可行性进行了理论探讨,分析高炉内部还原二氧化硫和氮氧化物,以及分解二噁英的热力学条件,探讨烧结烟气代替空气鼓风对理论燃烧温度、风量、炉缸煤气、炉顶煤气和铁水硫含量的影响.结果表明:二氧化硫、一氧化氮和二氧化氮的最低平衡体积分数分别为1.84×10^-13%、3.08×10^-11%和3.72×10^-21%,高炉内部还原二氧化硫和氮氧化物是可行的;高炉具有分解二噁英的有利热力学条件;烟气中二氧化硫和一氧化碳对理论燃烧温度的影响可忽略,氮氧化物能略微提高理论燃烧温度,二氧化碳体积分数增加1%,理论燃烧温度降低大约40.5℃,但通过降低鼓风湿度和提高富氧率等措施,能达到高炉正常生产时的炉缸热状态水平;随着烟气中二氧化碳含量的增加,风量、炉缸和炉顶煤气量都逐渐降低,炉缸煤气一氧化碳和氢气含量增加,炉顶煤气中一氧化碳、氢气、二氧化碳和水含量都增加,氮气含量显著降低;铁水硫含量与烟气二氧化硫含量成正比,但当二氧化硫质量浓度达到2000 mg·m^-3,铁水中硫质量分数仅为0.025%,铁水质量仍合格.通过综合调节高炉操作参数,也可以实现烧结烟气代替空气鼓风进行高炉炼铁生产,达到脱硫脱硝脱二恶英的目的.

Desulfurization and denitration of sintering flue gas by blast furnace process

The technical feasibility of desulfurization, denitration and dioxin removal from sintering flue gas processed by blast furnace was discussed in theory. The reduction thermodynamics of sulfur dioxide and nitrogen oxides as well as the conditions for dioxin decomposition in a blast furnace were analyzed. The effects of blast with sintering flue gas instead of air on the theoretical flame temperature (TFT), blast volume, gas in hearth, top gas and sulfur content of hot metal were investigated. The results show that sulfur dioxide and nitrogen oxides can be reduced in the BF interior, and the lowest equilibrium volume fractions of sulfur dioxide, nitric oxide and nitrogen dioxide are 1.84×10-13%, 3.08×10-11% and 3.72×10-21%, respectively. Favorable thermodynamic conditions for dioxin decomposition are found in the blast furnace. Sulfur dioxide and carbon monoxide in sintering flue gas have little effect on the TFT, while nitrogen oxides can slightly increase the TFT. The TFT decreases by about 40.5% with a 1% increase in carbon dioxide volume fraction of sintering flue gas, but the thermal state of a hearth can be improved to the normal level by reducing the humidity and increasing the oxygen enrichment of blast. The blast volume, gas in hearth and top gas decrease with increasing carbon dioxide content of sintering flue gas. As the carbon dioxide content of sintering flue gas rises, the carbon monoxide and hydrogen contents of gas in hearth and the carbon monoxide, hydrogen, carbon dioxide and water contents of top gas increase, but the nitrogen contents of gas in hearth and top gas decrease. The sulfur quality content of hot metal is proportional to the sulfur dioxide content of flue gas and it is raised to 0.025% when the sulfur dioxide content increases to 2000 mg·m-3. The BF production can proceed smoothly with sintering flue gas blast instead of air through comprehensive operating measures, achieving the purpose of desulfurization, denitration and dioxin removal.