气体燃料MILD氧燃烧的基础研究

Oxy-Combustion is generally named for the combustion of fuel with pure oxygen or the mixture of oxygen and CO2 or/and H2O. The MILD combustion under oxy-combustion conditions, simply named “MILD oxy-combustion”, is a new type of combustion technology recently developed to achieve near-zero exhaust emissions of combustion to Atmosphere. This technology firing gaseous fuels has started in Europe and America to be widely utilized in metallurgical and steel industries. However, the fundamental study of this combustion of gaseous fuels is still lacking and hence its application is hard to expand to other industries. Based on our previous work of MILD combustion, this project is proposed, by theoretical analysis, experimental measurements and numerical simulations together, to: (1) clarify the effects of reactants injection and in-furnace boundary conditions on the occurrence and evolution of MILD oxy-combustion; (2) explore the overall influences of non-premixing and premixing modes of initial fuel and oxidizer, as well as the degree of premixing, on this combustion; (3) examine how physical dispersion and chemical reactions take place in MILD oxy-combustion when fuel and oxidizer are sufficiently premixed; (4) understand the formation mechanisms of NO in MILD oxy-combustion of firing typical gaseous hydrocarbon fuels. The completion of this project will lay a strong ground for the MILD oxy-combustion and its industrial applications.

氧燃烧是燃料与纯氧或O2/CO2及O2/H2O混合物燃烧的统称；该燃烧在MILD条件下简称为MILD氧燃烧。后者是近年来发展的与CO2埋存相结合能实现近零排放的一种燃烧新技术，它在欧美钢铁冶金行业的燃气加热炉上已开始推广应用。但它的基础研究目前仍然苍白，工业应用范围窄且难以扩大。为填补此空缺，申请者在前期MILD燃烧研究的基础上拟通过实验测量和数值模拟等手段，深入探究预混与非预混条件下燃气MILD 氧燃烧的物化机制与控制原理。具体内容包括：（1）弄清反应物喷射条件和燃烧室边界条件对该燃烧反应的影响；（2）研究燃料与氧化剂初始非预混和预混两种模式以及预混程度对该燃烧的整体影响；（3）探究燃料与氧化剂初始充分预混模式对炉内物理扩散和化学反应的作用规律；（4）揭示几种典型的气体燃料在MILD氧燃烧下NOx的生成机理。项目的完成将夯实MILD氧的理论和应用基础。

MILD氧燃烧是MILD燃烧和富氧燃烧的结合，指的是燃料与纯氧或O2/CO2及O2/H2O混合物实现的MILD燃烧。这种新型燃烧是近年来发展的与CO2埋存相结合实现近零排放和碳中和的高效低污染燃烧的新技术之一，它在欧美钢铁冶金行业的燃气加热炉上已得到应用，但工业应用范围仍然狭窄，目前只局限在冶金行业。人们一直缺乏对氧燃烧条件下MILD模式燃烧发生发展背后物理化学机制的认识。本项目就是针对该燃烧开展的基础研究，并且填补了认识上的一些缺陷。我们在前期MILD燃烧研究的基础上，通过实验测量和数值模拟等手段，深入研究了预混与非预混条件下燃气MILD氧燃烧的发生与发展机制及其控制原理。已开展的研究包括：弄清了反应物喷射条件和燃烧室边界条件对该燃烧反应的影响；研究了燃料与氧化剂初始非预混和预混两种模式对该燃烧的发生与发展的影响；掌握了反应物充分预混条件下炉内MILD 氧燃烧的湍流混合和化学反应的作用规律；以及揭示了天然气和液化石油气MILD氧燃烧的NOx和CO的生成机制。通过燃烧天然气和液化石油气的实验测量以及详细的化学动力学计算，我们发现和证明了，相比MILD空气燃烧，MILD氧燃烧可以在更宽泛的条件下发生、发展和稳定燃烧，并且这个结论应该普适于各种气体燃料。这是具有重要科学意义和应用价值的！总之，本项目的完成夯实了MILD氧燃烧的理论基础，也同时拓宽了它的工业应用前景。