基于磁铁矿的生物质炭新型复合燃料高效过滤燃烧机理与调控机制研究

As biochar combusts at a extremely high rate with low combustion efficiency and low heat production, it is difficult to substitute biochar for coke in large-scale in the iron ore sintering filtration combustion process. In this project proposal, a new biochar-magnetite composite fuel was proposed in which the magnetite adhering layer acts as the diffusion barrier and also as the additional heat source for the biochar combustion process. The aim of this project is to increase the use of biochar in iron ore sintering and reduce the green house gas, NOx and SOx emissions by applying the proposed new composite fuel and to promote the sustainable development of the iron and steel industry..Firstly, the composite fuel with various structural parameters will be produced. With the characterization techniques, the relationship between the fuel structural parameters and the production process parameters can be developed. Furthermore, the single-particle scale, lab-scale ZrO2 packed bed and pilot-scale combustion experiments will be carried out along with the thermochemical and multi-scale numerical simulations. The evolution of fuel structure and the variation of iron oxides during combustion as well as their influence on the combustion process will be studied. A combustion model will be developed and the relationship between the fuel structure and combustion efficiency can be built. Based on the obtained results, the optimum structure of the composite fuel can be determined. The results of this project can provide guidelines for the large-scale application of biochar in the iron ore sintering industry.

针对生物炭燃烧速率过快、效率低、释热不足导致其无法大规模替代焦炭应用于铁矿石烧结过滤燃烧过程的现状，本项目提出以磁铁矿包覆层物理阻隔和释热补偿两种机制协同作用为特色的生物质炭-磁铁矿复合燃料，以求大幅提高生物质炭替代焦炭的比例，减少温室气体、NOx、SOx等污染物排放，促进钢铁工业可持续发展。.首先制备具有不同结构参数的复合燃料，借助燃料综合表征手段，构建制备过程参数与燃料结构参数定量关系。然后针对复合燃料依次开展单颗粒规模、实验室ZrO2堆积床和烧结床试验，结合化学热力学模拟与多尺度数值计算，探明燃料微观结构演变和铁氧化物转化规律及其对燃烧过程影响的耦合和协同作用机制，建立并精修耦合燃烧机理模型，构建复合燃料结构与燃烧效率调控关系。据此最终确定可实现替代目标的复合燃料最佳结构参数。本项目研究可为生物质炭在烧结工业大规模应用提供试验和理论依据。

为解决生物质炭燃烧速率过快、效率低、释热不足导致其无法大规模替代焦炭应用于铁矿石烧结过滤燃烧过程的问题，本项目提出一种新型生物质炭-磁铁矿复合燃料，开展了燃烧机理的实验与理论研究，以求大幅提高生物质炭替代焦炭的比例。. 项目首先开展了复合燃料制备及其物理、燃烧特性表征，构建了制备过程参数与燃料结构参数间的关系。然后，首次提出了考虑包覆特性的单颗粒多孔炭燃烧过程的解析模型，弥补了以往烧结模拟简单延用未包覆纯炭颗粒模型的缺点。结合模型与实验，研究了ZrO2堆积床和中试规模过滤燃烧过程中复合燃料替代焦炭的比例。首次提出了考虑惰性包覆层时实现包覆生物质炭与相同粒径焦炭燃烧速率相匹配的包覆层临界孔隙率计算的理论方法。研究结果表明，在给定温度下，临界孔隙率与临界炭颗粒半径几乎成线性关系，且随炭粒的燃烬而逐渐减小；优化的包覆层结构可实现复合燃料与焦炭的总体燃烧速率相匹配，但要实现以生物质炭复合燃料高比例替代焦炭，还需配合粒径优化与分组预制粒，保证各分组均具有最优的包覆结构参数。采用该方法可实现复合燃料替代比的大幅提升。. 本项目研究可为生物质能在烧结工业大规模应用、促成炭中和目标，提供试验和理论依据。

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