基于生命周期评价的钢铁厂碱渣固碳技术比较研究

本研究以3种钢铁厂碱渣直接法固碳技术为研究对象,该技术将钢渣进行碳酸化处理,可快速永久地将CO2固化储存在钢渣中,气固相反应可分别在高压釜、泥浆反应器和超重力旋转床的水溶液中一步完成,并将其分别定义为T1、T2、T3.通过Umberto软件建立生命周期模型,对3种技术的资源环境影响进行评估.结果表明,T1的环境影响最高,其次为T3,T2的环境影响最小.技术评价显示,T3在技术效率、资源消耗、环境影响方面具有较好的综合效益.敏感性分析表明,加热效率的敏感性系数分别为0.97、0.97和0.46.转换率与温室气体排放的关系分别呈上升、倒U型和下降的变化趋势.提高加热效率、合理利用热源及选择合适的技术效率,将有利于技术优化,减少技术的环境影响,提高固碳效率.

A comparative study of carbon sequestration technology by steelmaking slag based on life cycle assessment

Carbon capture and storage (CCS) is an effective technology for CO₂ reduction, and CO₂ utilization is an important part of some CCS technologies. Direct carbonation is an important emerging technology characterized by a large source of carbonation feedstock, near point sources of CO₂ emissions and a single step reaction. In addition to technology efficiency considerations, it is important to consider resource and environmental consequences by conducting a lifecycle assessment, which can effectively compare, assess, select and optimize alternative technologies. This paper presents a comparative LCA of three CO₂ sequestration technologies (T1, T2 and T3) from steelmaking slag. The slag carbonation processes can sequestrate the CO₂ permanently in autoclave, slurry and rotating packed bed to enhance the mass transfer between the gas, liquid, and solid phase. The lifecycle assessment scenarios are modelled in a material and energy flow network using Umberto software. The results showed that T1 had the highest enviromental impacts, followed by T3, while T2 had lowest impact. The technology assessment showed that T3 had the best integrated benefits in technology efficiency, resource consumption and environment impacts. Sensitivity analysis yielded indicator values of 0.97, 0.97 and 0.46 for T1, T2 and T3, respectively. The relationship between conversion and greenhouse gas emission was increasing, inverse-U shape and decreasing curve, respectively. Increased heating efficiency, the introduction of a combined heat and power system, and improved heat source and conversion favor technology optimization and minimize the environmental burden.