典型钢铁企业全流程的氮素流及其含氮污染物减排潜力分析

针对钢铁生产全流程产生的NO_x造成的环境污染问题,依据NO_x生成机理及元素流分析方法,建立钢铁生产全流程氮素流分析模型。应用该模型,以某典型钢铁企业实际生产数据为样本,分析钢铁联合企业的氮元素流动特征,讨论钢铁生产全流程中排放的含氮污染物及废气NO_x的产生、脱硝及排放情况。研究结果表明,钢铁企业输入的氮素主要来源于高炉鼓风和各工序燃烧所需的空气(99.655%),输出的氮素主要以N₂形式(82.917%)排放至大气,全流程内的氮素主要以煤气和工序产品形式循环;钢铁企业排放的含氮污染物以废气NO_x(97.982%)为主,高炉炼铁工序废气NO_x排放量最高;钢铁企业产生的废气NO_x主要来源于焦炭(56.84%)和煤炭(28.91%),其中24.23%的NO_x经脱硝后转化为N₂排放至大气。对钢铁生产全流程氮素流及含氮污染物的排放、控制及相关政策开展研究,提出合理建议,对中国环境保护和钢铁行业的绿色发展具有重要意义。

Analysis of nitrogen flow in the whole process of a typical iron and steel enterprise and reduction potentialof nitrogen-containing pollutants

Aiming at the environmental pollution caused by NO_x generated in the whole process of steel production, based on the NO_x generation mechanism and substance flow analysis method, an analysis model of nitrogen flow in the whole process of steel production was established. Using this model, based on the actual production data of a typical iron and steel enterprise, the nitrogen flow characteristics of the iron and steel complex were analyzed, and the production, denitrification and emission of nitrogen-containing pollutants and exhaust gas NO_x discharged in the whole process of iron and steel production were discussed, which could provide a theoretical basis for further research on NO_x emission reduction in iron and steel industry. The results show that the main source of nitrogen input by iron and steel enterprise is the blast furnace blast and the air required for combustion in each process (99.655%), the output of nitrogen is mainly discharged into the atmosphere in the form of N₂ (82.917%), and the nitrogen in the whole process is mainly circulated in the form of gas and process products. The nitrogen-containing pollutants emitted by iron and steel enterprises are mainly NO_x (97.982%), and the NO_x emissions from the blast furnace ironmaking process are the highest. The exhaust NO_x produced by iron and steel enterprises mainly comes from coke (56.84%) and coal (28.91%), of which 24.23% of NO_x is converted into N₂ after denitrification and discharged into the atmosphere. Researching on nitrogen element flow and nitrogen-containing pollutants emission, control and related policies in the whole process of iron and steel production, and putting forward reasonable suggestions are of great significance to China's environmental protection and the green development of the iron and steel industry.