煤气化细灰熔融过程铁的价态对熔渣流动特性的影响机理

The fine semi char derived from fluidized bed coal gasifier has high carbon content, which is the core problem affecting coal gasification efficiency and carbon conversion and becomes the barrier of the development of fluidized bed coal gasification technology. Melting of the fine semi char under reducing atmosphere is proposed, which can solve the issues such as low energy utilization efficiency and high pollutant emission. The mechanism of the residual carbon-slag interaction on slag flow properties in the fine semi char melting is unclear due to near zero volatile matter, the graphitic structure as well as high contents of iron and sulfur. Research on synergistic association mechanism between the chemical state distribution of iron and the complex phase change and slag fluidity is crucial to the breakthrough of melting technology of the fine coal gasified semi-char. From the view of the interaction among the iron-bearing mineral system, the complex mechanism of phase transformation of iron component intermediate and the liquid-solid phase equilibrium transformation, the proposal intends to study the oxidation-reduction equilibrium mechanism of the variable chemical state ion and the iron precipitation mechanism in the melting process of the coal gasified fine semi char, to reveal the effect of residual carbon in molten slag on slag viscosity and flow property, as well as to reveal the synergistic association characteristics of the effects of residual carbon and the chemical state transformation of iron components on slag flow property and the target high temperature gas products. The proposal has important theory value and practical significance for the development of fluidized bed gasification technology.

流化床煤气化炉尾部带出的细灰含碳量较高是影响煤气化效率及碳转化率的核心问题，限制了流化床煤气化技术的发展。本项目提出煤气化细灰还原性气氛熔融工艺解决其综合利用面临的能源利用效率及污染物排放等瓶颈问题的新思路。近零挥发分、石墨化结构与高铁硫含量等特点导致煤气化细灰熔融熔渣中残炭与灰分的反应转化对熔渣流动特性的影响机理尚不清楚。煤气化细灰熔融过程铁化学价态的转化与熔渣流动特性的关联机制是突破煤气化细灰熔融技术瓶颈的关键。拟从含铁矿物体系的相互反应、含铁组分中间产物复杂的相变和液固相平衡的转化角度，研究煤气化细灰熔融过程可变价离子的氧化还原平衡机制及析铁机理；研究熔渣中残炭对熔渣粘度的影响机理，揭示熔渣中残炭与含铁矿物化学价态的转化对熔渣流动特性及高温气体产物耦合影响的关联特性。本项目对于推动流化床煤气化技术的发展具有重要理论和现实意义。

煤气化炉尾部带出的细灰含碳量较高是影响煤气化效率及碳转化率的核心问题。本项目提出煤气化飞灰还原性气氛熔融工艺的新思路，主要研究成果如下：.揭示了还原性气氛高铁矿物体系相互作用及体系相变机制，掌握了高铁矿物体系、高钙矿物体系和高硫矿物体系熔融过程中物相转变机制和铁元素迁移转化路径。.研究了煤气化细灰高温熔融过程残炭及熔渣含铁矿物的转化机理，获得了残炭对于气化飞灰高温熔融过程中物相转变和铁元素迁移转化的影响规律和机理。.研究了煤气化细灰熔融熔渣中残炭与含铁矿物价态对熔渣流动性的作用机制，获得了碳含量对于熔融特性的影响机理，获得了熔渣性质变化与铁组分相变的关联机制。.研究了流态化改性对于煤气化飞灰的改性提质作用，掌握了流态化改性时氧气浓度对气化飞灰理化特性的影响规律，发现了流态化改性对气化飞灰灰熔融特性和高温流动特性存在改善作用。明确了熔渣中硅铝酸盐网络结构的聚合度与高温熔融冷却过程中黏温特性的关联机制。.本项目揭示了煤气化飞灰熔融过程残炭对熔渣粘度的影响机理，揭示了熔渣中残炭与含铁矿物化学价态的转化对熔渣流动特性影响特性，研究成果有力支撑了流化熔融新工艺的研发，实现首台十万吨级气化飞灰流化熔融工程应用，对于煤气化灰渣综合利用具有重要理论和现实意义。