Abstract:

To address issues of deep spatiotemporal coupling among multiple processes in steel production parks, extensive carbon emission accounting, and unclear emission reduction pathways, a carbon flow evolution model for the entire steel production process was constructed, and a carbon flow monitoring and tracking and carbon emission accounting method was proposed. Taking a steel park in Nanjing as the research object, an analysis was conducted on the carbon evolution pathways and CO₂ emission characteristics throughout the steel production process. The findings reveal that at the system level, carbon primarily originates from purchased coke, coking coal, and pulverized coal injection, and accounting for over 80% of the total carbon input. In terms of carbon flow, over 87% of the carbon is converted into direct CO₂ emissions, while only about 2% enters end products. Notably, pulverized coal injection has the highest CO₂ conversion rate at approximately 84%, whereas limestone has the lowest at only 43%. At the process level, the ironmaking process generates the largest amount of direct carbon emissions, followed by the self-generated power sector, with the steel rolling process producing the least. Within the coking process, the proportion of carbon converted into products is the highest, while the proportion emitted as CO₂ is the lowest. The converter gas recycling rate is the highest in the steelmaking process, and the proportion of carbon converted into CO₂ emissions is the highest in the steel rolling process. Based on the system's carbon evolution pathways and the carbon conversion mechanisms of each process, a new method for accounting product carbon emissions was proposed. Additionally, the correlation mechanism between energy losses from by-product gases (such as gas venting and inefficient gas-powered generation) and carbon emissions was clarified, along with a series of recommended emission reduction pathways.

Key words: steel production, carbon flow evolution, carbon flow model, carbon emissions

摘要：

针对钢铁生产园区多工序时空深度耦合、碳排放核算粗放及减排路径不清等问题，构建了钢铁生产全流程碳流演化模型，提出碳流监测追踪及碳排放核算方法。以南京某钢铁园区为对象开展了钢铁生产流程碳演化路径及CO₂排放特性分析。研究发现：系统层面，碳元素主要来源于外购焦炭、炼焦煤和喷吹煤粉（超过80%）；去向上碳主要转化为CO₂直接排放（超过87%），进入产品的最少（仅约2%）；其中，喷吹煤粉转化为CO₂的比例最高（约84%），而石灰石最低（仅43%）。工序内部，直接碳排放量最大的是炼铁工序，自发电环节次之，轧钢工序最低；焦化工序内部碳转化至产品中的比例最高，转化至CO₂排放的占比最低；炼钢工序的转炉煤气循环利用率最高；轧钢工序内碳元素转化至CO₂排放的比例最高。根据系统碳演化路径及各工序碳转化机制，提出一套新的产品碳排放量核算方法；阐明了煤气放散、煤气低效发电等副产气能量损失对碳排放的关联机制，提出一系列减排路径。

关键词: 钢铁生产, 碳流演化, 碳流模型, 碳排放