煤基固体燃料O2/H2O燃烧关键基础问题的研究

For energy conversion with high efficiency and low carbon emission, Oxy-Coal Combustion Steam System for power generation with near-zero emissions (OCCSS) was proposed by the applicants. To make the system, the demineralised coal burns with pure oxygen with the presence of steam under the conditions of high pressure, high temperature, high steam concentration and high oxygen concentration (namely “four high” condition), which make it possible to convert chemical energy from solid fuels directly to the enthalpy of work media in the same space of combustor, then gases produced, i.e. mixture of CO2 and H2O, go to an advanced turbine to finish work. The exhaust gases from turbines are condensed into water and CO2 of high purity, which enables high conversion efficiency and near-zero emission of CO2 simultaneously. This research project will be undertaken by an inter-disciplinary team, by means of quantum chemistry theories and simulation tools, and the measurement of important free radicles in coal flame with laser diagnostics, and will focuses on the study of combustion theory of demineralised coal and its raw coal under O2/H2O and elevated pressures, including 1) kinetics of pyrolysis and combustion; 2) The kinetics of the main combustible components of the volatile from demineralised coal/raw coal (CO/H2/CH4); 3) The evolution of nitrogen and sulphur related components during combustion under high steam concentration. This study will clarify propagation of CO/H2/CH4 premix flame in O2/H2O under elevated pressure, mechanism of char nitrogen and char sulphur immigration and conversion, as well as of NO and SO2 formation. Furthermore, this study will build kinetic model of pyrolysis and combustion of demineralised coal and raw coal, as well as kinetic model of CO/H2/CH4 in O2/H2O under elevated pressure. Finally, this study will set up a solid theoretical foundation for the successful development of OCCSS system and similar systems.

为实现高效低碳能源转化，本项目组提出了煤基固体燃料-氧-水蒸气燃烧近零排放发电系统（OCCSS）：脱灰煤在燃烧室内与O2/H2O燃烧，在同一空间内实现固体燃料的化学能-工质焓直接转化，CO2/H2O混合物做功后冷凝，直接得到高浓度CO2，实现低成本碳捕集。本项目组建跨学科团队，借助量子化学理论和计算工具、先进激光火焰诊断技术对煤粉火焰重要自由基的测量，研究脱灰煤和原煤在加压O2/H2O条件下的燃烧理论，包括：1）热解动力学及焦炭燃烧动力学；2）挥发分主要可燃成分（CO/H2/CH4）的燃烧反应机理；3）氮、硫演变机制。本研究将揭示加压O2/H2O条件下CO/H2/CH4预混燃烧的火焰传播特性，焦炭氮、硫迁移和转化机制以及NO、SO2生成规律。建立脱灰煤和原煤热解和燃烧动力学模型，加压O2/H2O下CO/H2/CH4燃烧的反应机理模型。为OCCSS等相关系统的发展奠定理论基础。

为实现高效低碳能源转化，本项目组提出了煤基固体燃料-氧-水蒸气燃烧近零排放发电系统（OCCSS）：脱灰煤在燃烧室内与O2/H2O燃烧，在同一空间内实现固体燃料的化学能-工质焓直接转化，CO2/H2O混合物做功后冷凝，直接得到高浓度CO2，实现低成本碳捕集。本项目组建了跨学科团队，借助量子化学理论和计算工具、先进激光火焰诊断技术对煤粉火焰重要自由基的测量，研究了脱灰煤和原煤在常压/加压O2/H2O条件下的热解动力学及焦炭燃烧动力学、挥发分主要可燃成分（CO/H2/CH4）的燃烧反应机理以及氮硫演变机制。.研制了加压沉降炉和加压高温筛网反应器；适合煤基固体燃料燃烧特性研究的高时空分辨光学成像测量与分析平台，包括高速平面激光诱导荧光成像系统和高速自发辐射荧光测量系统，可测量自由基（OH、CH）和气态组分（NO、NH3），工作频率范围为10Hz-10kHz。.研究了脱灰煤和原煤的碳骨架结构在热解中的变化规律和模拟方法、焦炭的燃烧特性以及H2O的影响规律、测量了火焰传播速度。完成了高频、高分辨率单颗粒煤粉点火及挥发分燃烧过程成像测量研究，建立了煤粉燃烧进程信息提取方法与群燃煤粉振荡特性测量与分析方法，利用多组分试验结果，分析了煤粉燃烧振荡机理。.利用反应动力学计算，在原子分子水平上揭示了O2/H2O条件下水蒸气对系列燃烧反应OH+CO、OH(H2O)+CO、Cl+C2H2、CH4+OH、振动激发下HOCO自由基等的作用机制、微观机理和能量传递情况。发展了适用于燃烧网络中典型动力学过程的研究方案及工具，可用于获取基元反应微观机制以及精确的化学反应速率常数，特别的提供了研究涉及激发态物质的电子非绝热过程的方法及工具。.试验测量了CO/H2/CH4/O2/H2O预混气火焰传播速度，优化了以GRI 3.0机理为基础的反应动力学模型，获得了详细的火焰传播速度数据集。.研究了O2/H2O燃烧条件下脱灰煤焦表面N元素赋存形态的转化规律、碳转化和焦炭氮转化模型、H2O的影响规律、以及煤热解过程硫迁移和转化规律。.研究成果将为OCCSS和其他加压富氧燃烧系统的发展奠定理论基础。