【作者】 张小辉；

【导师】 周孑民； 张家元；

【作者基本信息】 中南大学 ， 动力工程及工程热物理， 2013， 博士

【摘要】 摘要：我国的钢铁产量连续多年居世界第一,但是钢铁生产过程的能耗量和排放水平均远高于世界先进水平,节能减排潜力巨大。而铁矿石烧结在我国的钢铁企业生产过程中能耗居第二,排放居第一,对钢铁工业的节能减排起着决定性作用,因此,研究开发能降低铁矿石烧结过程的能源消耗量和烟气排放量的烧结改进工艺对我国钢铁行业的可持续发展具有重要意义。烟气循环烧结技术通过对烧结烟气的循环使用,可以提高料层温度的稳定性和降低烟气排放量,燃料分层布料技术通过对烧结料层内固体燃料的合理分布,可以降低固体燃料的消耗,使料层温度分布更加合理。目前国内外对这两种铁矿石烧结过程节能减排技术的研究和应用处在起步阶段,研究方式也多是半工业化试验,而随着计算机仿真技术的发展和对铁矿石烧结过程各种机理研究的不断深入,使得利用数值仿真技术对铁矿石烧结过程节能减排的研究更方便和直接。论文通过对铁矿石烧结过程的流动、传热、传质、料层结构变化机理的深入分析,建立了完整的铁矿石烧结传输过程的非稳态数学模型和数值方法。利用此模型对常规烧结工艺过程进行了模拟计算,根据料层温度在深度方向上的分布以及烧结烟气随时间的变化,提出了以部分烧结烟气和烧结矿冷却过程产生的废气相混合的烟气循环烧结改进工艺以及燃料分层布料烧结改进工艺。在烟气循环烧结工艺的研究过程中,根据对烧结系统的余热利用以及减量排放侧重点的不同提出了三种烟气循环烧结方案,并首次提出了基于料层温度的烧结矿质量评价指标；在燃料分层布料烧结工艺的研究过程中,提出了以料层最高温度为控制目标的基于深度单元的燃料分层分布工艺。并基于这两种烧结改进工艺,创新性地提出了基于燃料分层分布的烟气循环烧结综合优化工艺。对文中提出的各种烧结工艺均进行了模拟计算和效益分析。研究发现,烟气循环烧结工艺对烧结过程的改善主要体现在降低烧结烟气的排放处理量和提高料层上部温度两方面；燃料分层布料烧结工艺对烧结过程的改善主要体现在使料层的最高温度在深度方向上分布更均匀和促进燃料的合理利用两方面；基于燃料分层布料的烟气循环烧结综合优化工艺则能全面提高烧结矿质量评价指标,增加烧结系统余热利用量,降低烧结周期、固体燃料使用量、烟气排放处理量以及SO2总排放量。本文所提出的三种烧结改进工艺中,在提高质量与节能减排效益方面综合优化工艺最优,在提高产量方面烟气循环烧结工艺最优。该研究有助于理解铁矿烧结传输过程的机理,为铁矿石烧结过程节能减排的研究提供了参考依据,并且对于提高铁矿石烧结过程的生产效率,降低烧结系统运行成本,提高企业竞争力具有重要意义。更多还原

【Abstract】 Abstract:The steel production of China ranking first in the world last for many years, but the energy consumption and emissions in steel production process are much higher than the advanced level of the world. This creates a huge potential for energy-saving and emission-reduction. In China, iron ore sintering plays a crucial role in iron and steel industry for its energy consumption ranking second and emissions ranking first in the steel production process. Therefore, it is of great significance for sustainable development of iron and steel industries to research and develop improved iron ore sintering technology which can reduce energy consumption and flue gas emissions.Flue gas circulation sintering (FGCS) technology can improve the stability of the sintered bed temperature and reduce emissions by recycling flue gas. Fuel layered distribution (FLD) technology can reduce the consumption of solid fuel and rationalize the distribution of sintered bed temperature through distributing solid fuel reasonably. Till now, research and application of the two technologies are still in infancy and most of the research methodologies are semi-industrial tests. Due to the development of computer simulation technique and the intensive study of various mechanisms in sintering process, it is more convenient and direct to study the energy-saving and emission-reduction in iron ore sintering.An unsteady mathematical model and numerical methods of transport process in iron ore sintering are established through intensively studying the mechanisms of flow, heat and mass transfer as well as structure change. The conventional sintering process is simulated with this model. The FGCS process of mixing flue gas in sintering and exhaust gas in sinter cooling and fuel layered distribution sintering (FLDS) process are proposed according to the distribution of sintered bed temperature in the depth direction and the flue gas changes over time. In researching the FGCS process, three schemes are proposed in accordance with different emphasis of waste heat utilization and emission-reduction in sintering system, and the quality evaluating indicator of sinter based on sintered bed temperature is first put forward., The FLD technology based on depth unit is proposed in researching the FLDS process, and its control target is the highest temperature of sintered. The synthetical optimization sintering process (SOSP) is innovatively proposed based on the two technologies above. Simulation and benefit analysis of the processes in the thesis are accomplished.The research result reveals that the improvements of sintering by using the FGCS process are reducing the flue gas emissions and improving the temperature of top sintered bed, the FLDS process can ameliorate the sintering through uniformizing the highest temperature distribution in depth direction and promoting the rational use of fuel, the SOSP can comprehensively improve quality evaluating indicator of sinter and waste heat utilization and decrease sintering cycle, solid fuel usage, flue gas emissions and total emissions of sulfur dioxide. In the above three processes, the SOSP is optimum in improving sinter quality and the effect of energy-saving and emission-reduction, and the FGCS process is optimum in increasing production.This study will help to understand the mechanisms of complex transport process in iron ore sintering and providing references for studing on sintering energy-saving and emission-reduction. The research is significant in increasing productivity, decreasing operating costs and improving competitiveness of iron and steel enterprise.更多还原