Computational Analysis of The Performance of Shaft Furnaces with Partial Replacement of The Burden with Self-Reducing Pellets Containing Biomass

The shaft furnace knowed Midrex™ is used for the production of direct reduced iron with the use of reformed gas. Another process based on shaft reactors is the Tecnored process, which exhibits the great advantage of using self-reducing agglomerates. Therefore, it was proposed a combination of the shaft furnace for direct reduction with self-reducing pellet burden. In addition, with the aim of improving the furnace efficiency and reducing the need for reformed gas, the injection of natural gas and oxygen into the bustle region is proposed. Thus, it is possible exploit the advantages of direct reduction involving high amounts of hydrogen and faster reactions of the self-reducing process to decrease the CO2 emission, compared to that of blast furnace. The energy profile, productivity, and carbon emission of the traditional shaft furnace were compared with the simulated results after partial replacement of the burden with self-reducing pellets containing fines of elephant grass charcoal. The simulation results for a combination of 15% of self-reducing pellets in the burden with 2.5% oxygen and natural gas injection were the best among the scenarios simulated, with the productivity being 2.7 ton/m3 day and the decrease in the amount of reformed gas being 10%.

以米德莱克斯（Midrex™）竖炉为代表的工艺通过重整气制备直接还原铁（direct reduced iron）。另一类基于竖炉反应器（shaft reactors）的特诺雷德工艺（Tecnored process），则具备使用自还原团矿（self-reducing agglomerates）的显著优势。据此，本研究提出将直接还原竖炉与自还原球团炉料（self-reducing pellet burden）相结合的工艺方案。此外，为提升炉效并降低重整气消耗，本研究提出向热风围管区域（bustle region）喷吹天然气与氧气的优化策略。如此便可充分利用高氢直接还原与自还原工艺反应速率快的双重优势，相较于传统高炉（blast furnace）工艺，实现二氧化碳（CO₂）排放的削减。本研究对比了传统竖炉的能量分布（energy profile）、生产率与碳排放（carbon emission）水平，以及炉料部分替换为含象草炭粉（elephant grass charcoal）的自还原球团后的模拟结果。在所有模拟工况（scenarios）中，当炉料掺入15%自还原球团并辅以2.5%的氧气与天然气喷吹时，模拟效果最优：其生产率可达2.7吨/(立方米·天)，重整气消耗量降低10%。