【作者】 揭涛；

【导师】 王勤辉； 王树荣； 方梦祥；

【作者基本信息】 浙江大学 ， 热能工程， 2008， 硕士

【摘要】 煤炭在我国一次能源的生产和消费结构中一直占主导地位,随着能源消费的持续增长,环境问题的逐渐显现,煤炭的清洁利用越来越受人们的关注。煤炭气化是发展煤炭洁净转化的主要技术之一,其中压力流化床煤炭气化以其煤种适应性强,污染物排放低等特点成为煤炭气化技术的一个重要发展方向。煤灰熔融特性是动力用煤和气化用煤的一项重要的质量指标,直接决定着煤炭燃烧气化过程排渣方式的选择,是影响煤炭燃烧和气化运行的一个重要因素。本课题拟针对压力下煤灰的熔融特性和烧结特性开展一系列实验和理论研究,希望为煤炭气化系统设计和运行提供一定的帮助。首先,归纳分析了不同气氛下煤灰碱金属化合物对煤灰熔融特性的影响实验结果,发现不同气氛、不同煤灰化学成分对煤灰的熔融性的影响不同,煤灰熔融温度不仅与Fe₂O₃和CaO总含量有关,而且与其CaO/Fe₂O₃摩尔比也有关。其次,利用压力热天平分析仪和X射线衍射分析仪,对不同压力、不同气氛煤灰矿物质的转变情况进行实验研究,研究表明压力会影响煤灰矿物质化学反应平衡,压力抑制方解石、硫酸钙和钾云母的分解,促进石英的相变,以及莫来石、钙长石和铁尖晶石等矿物质的生成,对煤灰熔融特性影响复杂。然后,利用搭建的压差法实验台,对课题目标煤进行了烧结特性的实验研究,分析了主要煤灰化学成分对煤灰烧结特性的影响规律,以及气氛条件对煤灰烧结特性的影响规律,结果显示,煤灰中的CaO、Na₂O成分降低了煤灰烧结温度,与氧化性气氛相比,还原性气氛降低了煤灰烧结温度,其降低程度与煤灰中Fe₂O₃含量有关。最后,利用热力学计算软件对不同压力、不同气氛下煤灰矿物质反应过程进行模拟计算,分析了各种工况下,煤灰各矿物质生成情况,从理论上对各种气化条件下煤灰矿物质反应情况进行研究。计算表明,随着加热过程的进行,煤灰逐渐由低温矿物质转变为高温矿物质;压力条件能够抑制硫酸钙的分解反应,促进莫来石、钙长石和堇青石的生成以及石英的相变;还原性气氛主要通过和煤灰中的含铁化合物反应来改变煤灰的矿物质组分,进而影响煤灰的熔融特性。更多还原

【Abstract】 Coal is the dominant energy in the energy production and consumption structure of our country. With continued growth in energy consumption, environmental issues appear gradually, and the clean use of coal is concerned by increasing people. Coal gasification is the development of clean coal technologies, and pressurized fluidized bed coal gasification with its coal adaptability, and low emissions is to be an important development direction.The fusibility of coal ash is an important characteristic in pulverized coal combustion and coal gasification, which determines how to utilize coal resources in coal combustion or gasification. But there are some operation problems such as bed fusion, bed agglomeration and deposition in fluidized gasification technology, the paper mainly did experimental and theoretical research on coal ash fusibility which is important to solving these problems.Firstly, analyzed the influences of coal ash characteristics and atmosphere on coal ash fusibility, the results shows the fusion temperature is not only concerned with the sum of CaO and Fe₂O₃, but also with the ratio of CaO and Fe₂O₃;Secondly, experiments on the pressure thermal-balance apparatus and XRD, analyzed the influences of pressure and atmosphere on the mineral transformation in the coal. The results shows that the pressure will influence the balance of ash mineral chemical reactions suppress calcite, sulfuric acid Calcium and potassium mica decomposition and promote the transformation of quartz and mullite, calcium and iron spinel. The impact of pressure on the fusibility of coal ashes is complex.Then, analyzed the sintering temperature of coal ashes which is adding additives alter the proportion of alkaline oxides under different atmospheres. The results show the sintering temperature under coal gasification condition is lower than that under oxidizing atmosphere. And with the increase of Fe₂O₃, CaO, Na₂O content, the sintering temperature decreases.At last, we used the calculation software-FACTSage to simulate the influences of pressure and atmosphere on the mineral transformation in the coal ashes. Calculation shows that, with the heating process, the low-temperature minerals gradually transformed into high-temperature minerals; pressure suppress calcium sulfate decomposition and promote the transformation of mullite, anorthite, and cordierite. Reducing atmosphere, mainly through reacting with iron compounds, change the ash mineral components, thereby affecting the fusibility of coal ashes.更多还原