分层供热富氢烧结关键技术探索与研究

 中国提出2030年碳达峰、2060年碳中和的“双碳”战略以缓解温室效应带来的环境问题。钢铁是仅次于火电的国内第二碳排放大户,作为钢铁行业中的核心环节,烧结工序的碳减排已是必然趋势。常规烧结工艺中,料层中固体颗粒燃料难准确满足“自蓄热效应”要求的“上多下少”的分布要求,导致料层内部供热不均、成矿质量差、能效低下,且易出现微观局部还原性气氛,对烧结成矿和烟气中CO增多造成负面影响,制约了烧结节能减碳水平的提升。对此,作者研究了燃料形态、燃料分布对烧结的影响规律,提出了“分层供热富氢烧结”理念,阐述了厚料层烧结条件下料层上、中、下各层不同的气固组合供热方法,即顶层依靠富氧点火耦合固体燃料供热、上中层依靠富氢燃气喷加耦合固体燃料供热,下层依靠水蒸气喷加耦合固体燃料供热,同时探明了对应该方法的分层供热低碳烧结机理,详细阐述了富氧点火耦合固体燃料顶层供热、富氢燃气喷加耦合固体燃料中上层供热、水蒸气喷加耦合固体燃料下层供热等关键技术及其技术效果,并对应用上述技术可能出现的烧结过湿层恶化问题提出了解决办法。通过这些技术的集成应用,可以大幅降低烧结工序能耗,减少烧结工序碳消耗、碳排放及其他污染物排放,并改善烧结矿质量。

Exploration and research on key technologies of multi-layer heat supplying and H2-rich sintering

In order to manage the environmental problem caused by greenhouse effect, China aims to peak its carbon dioxide emissions before 2030 and achieve carbon neutrality by 2060. The iron and steel industry ranks second just after the thermal power industry in terms of the carbon emission. Therefore, reducing carbon emission in iron ore sintering is an irresistible trend. In the conventional sintering, it is hard for the solid fuel particles to disperse more in the upper bed and less in the lower bed which is essential due to the heat auto-accumulation effect. Consequently, it is inevitable that the reducing atmosphere is locally present which brings about extra CO in the flue gas and adverse impacts on the sintering process, and the uneven heat pattern impairs the sinter quality and the energy efficiency. All these restrict the improvement of energy-saving and low-carbon emission in sintering process. Based on the analysis of the effects of the fuel form and fuel distribution on the sintering process, the "multi-layer heat supplying and H₂-rich sintering" idea was proposed, which provided a new heat supplying method for upper, middle and lower layer in deep bed sintering condition. With the new method, the upper bed is heated up by the oxygen-rich ignition and solid fuel combustion, the middle bed by the combustion of H₂-rich gas and solid fuel while the lower bed by the steam injection and solid fuel combustion. The low carbon combustion mechanism as well as the key technologies of the new method were elaborated. The solution to the possible deterioration of the wet layer in the application of the technologies was also put forward. The integration application of these technologies would help to reduce energy cost, carbon as well as other pollutants emission,and improve the sinter quality.