协同处理钢厂固废工艺的物质流和能量流分析

Analysis of material flow and energy flow in synergistic treatment of solid waste in steel mills

为综合回收利用钢铁企业产生的固体废弃物,提出了一种多膛炉-转底炉-熔态电炉协同处理固废的工艺。基于质量和能量守恒定律,建立了物质流和能量流的解析模型,计算并分析了物质和能量在工艺流程中内部循环的潜在节能效果,考察了熔态电炉系统中不同金属化率的球团以及不同炉料结构对系统能效的影响规律,分析了不同指标参量下协同工艺的协同度变化。研究结果表明,焦油渣热解后的热解气及残渣(高碳)可分别用作燃气与还原剂进一步利用,热解1 t焦油渣产生高热值热解气和残渣分别为534 kg/t和466 kg/t。此外,对熔态电炉系统的炉料结构分析表明,随着金属化球团金属化率提高,熔态还原过程得到的渣量和二次锌粉量变化不大,产生的烟气量和吨铁耗电量呈线性下降趋势;随着入炉料中电炉粉尘生球团质量分数的增加,产生的烟气、炉渣、二次锌粉和吨铁耗电量分别呈现不同的线性增加,电炉粉尘生球团的原料占比由30%增长到80%,冷、热装料电耗差由相差200 kW·h/t缩小至65 kW·h/t。通过对协同工艺的协同度变化分析可得,在转底炉生产金属化球团的金属化率为80%,且金属化球团对铁水贡献率在40%时协同工艺系统的协同度最好,达到0.472。协同工艺的构建能够实现钢厂固废资源的梯级利用和高效回收,未来可进一步创造更高的社会价值和经济效益。

In order to comprehensively recycle the solid waste produced by iron and steel enterprises,a process of multiple hearth furnace,rotary hearth furnace and molten electric furnace synergistic treatment of solid waste was proposed in this paper.Based on the law of conservation of mass and energy,the analytical model of material and energy flow was established.The potential energy saving effect of material and energy in the internal circulation of the process was calculated and analyzed.The influence of different metallized pellets with different metallization rates and different structure composition of charge on the energy efficiency of molten electric furnace system was investigated.And the change of the cooperation degree of different index parameters was analyzed.The results show that the pyrolysis gas and residue(high carbon)can be used as gas and reducing agent respectively,and the high calorific value gas and residue produced by pyrolysis tar residue are 534 kg/t and 466 kg/t,respectively.In addition,the analysis of the charge structure of the molten electric furnace system shows that with the increase of the metallization rate of the metallized pellets,the amount of slag and secondary zinc powder obtained during the molten reduction process do not change much,and the flue gas and power consumption per ton of iron show a linear downward trend.With the increase of the mass fraction of electric furnace dust pellet in the charging material,the power consumption of flue gas,slag,secondary zinc powder and ton iron respectively presents different linear increases.The raw material proportion of electric furnace dust pellet increases from 30%to 80%,and the power consumption difference between cold and hot charging decreases from 200 kW·h/t to 65 kW·h/t.Through the analysis of the synergy degree change of the collaborative process,it can be concluded that the synergy degree of the collaborative process system is the best,reaching 0.472,when the metallization rate of the metallized pellets produced in the rotary hearth furnace is 80%and the contribution rate of metallized pellets to hot metal is 40%.The construction of collaborative process can realize the stepwise utilization and efficient recovery of solid waste resources in steel mills and further create higher social value and economic benefits in the future.