高炉喷吹生物质水热炭的可行性分析

 钢铁生产制造过程消耗大量化石燃料,同时排放大量CO₂和污染物,降低钢铁生产过程CO₂排放成为实现钢铁工业“碳达峰”和“碳中和”目标的关键。生物质作为植物光合作用的产物,具有产量大、可再生、碳中性的特点,是唯一具有可再生性能的含碳清洁能源,具备良好的可存储性和易运输特点,将丰富的生物质资源高效应用于高炉炼铁生产成为钢铁工业实现绿色可持续发展的关键。但生物质普遍具有水分含量高、固定碳含量和发热值低、碱金属(K、Na)有害元素多和粉碎性能差的缺点,不经炭化处理难以满足高炉炼铁生产对喷吹燃料的工艺性能要求。对比分析了热解炭化和水热炭化技术原理的差异,并对两种技术制备获得生物质炭的高炉喷吹基础性能和工艺性能进行了系统检测。结果表明,热解炭化能够脱除生物质中的挥发分,提升固定碳的含量和发热值,但灰分和碱金属元素在热解过程中会富集到生物质炭中,造成热解生物质炭中灰分和碱金属元素含量大幅增加,4种生物质热解炭中碱金属元素质量分数普遍大于1%,远超高碱度煤中碱金属元素含量的标准,不能作为喷吹燃料替代煤粉进行高炉喷吹生产。水热炭化在脱除挥发分的同时,能够有效脱除溶解生物质中的矿物元素,制备得到的生物质水热炭具有灰分和碱金属元素含量低、固定碳和发热值高的特点,同时生物质水热炭还具有高的可磨性和优良的燃烧性能,能够满足高炉喷吹的要求。生物质水热炭化技术解决了生物质能量密度低、有害元素含量高、粉碎和喷吹困难等限制性问题,通过生物质水热炭化技术制备优质碳中性燃料进行高炉喷吹新技术的实施,支撑了宝武集团实现绿色低碳炼铁。

Feasibility analysis of biomass hydrochar injection for blast furnace

Iron and steel production consumes a lot of fossil fuels, emits CO₂ and discharges pollutants. Reducing CO₂ emissions in the process of iron and steel production has become the key to achieve the goal of "carbon peak" and "carbon neutrality" for the iron and steel industry. Biomass as a product of plant photosynthesis, which has the characteristics of large yield, renewable and carbon neutral, is the only renewable carbon source with good storage and easy transportation characteristics. The efficient application of abundant biomass resources in iron-making with blast furnace has become the key to achieve green and sustainable development of iron and steel industry. However, biomass generally has the disadvantages of high moisture content, low fixed carbon content and calorific value, more harmful elements of alkali metals (K, Na) and poor crushing performance. Without carbonization treatment, it is difficult to meet the requirements for the process performance of fuel injection for blast furnace iron-making. The differences of pyrolysis and hydrothermal carbonization (HTC) technology principle was analyzed, and two type preparation technologies of biomass carbon and the basis performance and processing property of blast furnace injection was investigated. Results showed that the pyrolysis carbonization can remove the volatile in biomass, improve fixed carbon content and calorific value, but the ash and alkali metal elements will be enriched into biomass during pyrolysis. The content of ash and alkali metals in pyrolysis biomass was increased significantly, and the alkali metal content in four pyrolysis biomass was more than 1%, far above the standard for alkali metal content in coal with high basicity, which cannot meet the requirements of blast furnace injection. Hydrothermal carbonization could effectively remove volatile and dissolved mineral elements of biomass. Biomass hydrochar prepared had low content of ash and alkali metal, high fixed carbon and calorific value, high grindability and excellent combustion performance, which was met the requirement of blast furnace injection. The biomass HTC technology solves the restrictive problems of low biomass energy density, high content of harmful elements, and difficulties in grinding and injecting. The implementation for new technology of high quality carbon-neutral fuel for blast furnace injecting through the biomass HTC technology is beneficial to Baowu Group to achieve green and low-carbon iron-making.