【作者】 刘彦丰；

【导师】 宋之平； 阎维平；

【作者基本信息】 华北电力大学 ， 热能工程， 2002， 博士

【摘要】 煤燃烧产生的二氧化碳是温室气体的主要成分。近年来，世界上已有许多研究机构和研究者开始对电站燃料烟气中CO₂的收集和储存技术进行研究。采用纯氧与烟气再循环的煤粉燃烧（又称O₂／CO₂燃烧技术）是其中的一项重要新技术。 对该技术的研究表明：与煤粉在空气中的燃烧相比，煤粉在O₂／CO₂气氛中燃烧的火焰温度下降、稳定性变差；采用合理的燃烧配风方式可以有效地提高火焰温度水平。但目前国内外对该燃烧技术中所涉及的煤粉燃烧机理研究还很少。 本文对已有的煤焦颗粒燃烧理论、研究方法和试验结果等进行了分析和总结。在此基础上，采用一个能够同时考虑碳粒表面C-O₂、C-CO₂非均相反应和CO-O₂均相反应的复杂燃烧机理模型，对无孔纯碳颗粒在O₂／CO₂混合气氛中的燃烧特性进行了研究。得到了准静态燃烧过程下，气相温度、混合气氛中O₂／CO₂体积比、颗粒粒径及化学动力学参数等因素对碳颗粒燃烧速率的影响。 采用热天平（TGA）对两种煤焦颗粒分别在O₂／CO₂、O₂／Ar和纯CO₂气氛下的燃烧和气化特性进行研究。得到了处在化学动力学控制区域范围内煤焦与O₂、CO₂反应的动力学参数，以及高浓度CO₂的存在对煤焦与氧反应的影响。在对理论模型分析改进的基础上，对试验结果做了模拟计算。 设计、制作了高温管式气体携带炉（EFR）试验系统，对较高温度下单颗粒煤焦在O₂／CO₂、O₂／N₂和纯CO₂气氛下的燃烧和气化特性进行了研究。得到了在气流携带条件下焦颗粒的燃尽率随O₂／CO₂体积比、气相温度的变化。结合煤焦结构的特点，对纯碳颗粒的燃烧模型进行了合理修正，对试验结果做了模拟计算。 最后选取合适的炉内湍流流动、燃烧与传热的数学模型，以加拿大能源技术研究中心0.29MW煤粉燃烧试验炉为研究对象，利用Fluent5.0对一个二维轴对称、旋流、垂直筒式炉内的煤粉燃烧过程进行模拟。得到了不同O₂／CO₂体积比的气氛下，其炉内的流动状况、温度水平、气相辐射特性等的变化，并与已有的试验结果进行了比较。更多还原

【Abstract】 CO2 emitted from coal combustion is the bases of greenhouse gases. In recent years, many institutions and researchers are investigated the technologies of collecting and depositing CO2 in the world. One of the important technologies is the coal combustion in pure oxygen and recycled flue gases (021C02). The available results show that the flame temperature of coal combustion in 02/C02 atmosphere is lower and the stability is poor compared with that in air. But the flame temperature can be enhanced effectively by adjusting air distribution. However, few studies have focused on the mechanism of coal combustion and gasification referred in this technology. First the theory, study method and some experimental results of coal char particle combustion has been summarized in this thesis. And some key issues in coal char combustion are also analyzed. Based on the suitable carbon combustion model, the combustion of solid carbon ball in 02/C02 atmosphere has been predicted. The carbon combustion rates in static state and in different gas temperatures, mole ratios of 02/C02, particle diameter and chem.-dynamic parameters are acquired. The experiments of combustion and gasification of two kinds of coal char particle in 02/C02 ~. 02/Ar and pure CO2 atmosphere have been carried out in thermal gravimetric analysis. The dynamic parameters of the reaction between coal char and Q2~ CO2 have been estimated from the results. The influences of high CO2 concentration on the reaction between coal char and oxygen in lower temperature have been observed. A corrected model was used to simulate the experiment process. A high temperature entrained flow reactor (EFR) was designed in this work. And the experiments of combustion and gasification of the same coal char particle in 02/C02 02/N2 and pure CO2 atmosphere have been carried out in this test system. The burnout ratios of coal char in entrained flow status and different mole ratio of 02/C02 and gas temperatures are obtained. For using the pure carbon particle combustion model on coal char combustion, a suitable method has been proposed in this thesis. The measurement data are in general agreement with predicted results using this model. The Fluent5.O software is used for modeling the coal combustion process of two-dimension axis symmetry and swirling flow vertical furnace. The flow, combustion and heat transfer model are analyzed and selected. The change of flow status, the temperature level and gas radiate characteristic in different 02/C02 mole ratio are studied. Some predicted results are compared to measured data. The principle of adjusting rule of 02/C02 mole ratio for 02/C02 combustion technology is proposed in this thesis.更多还原