【作者】 丁佳佳；

【导师】 杨天华；

【作者基本信息】 沈阳航空航天大学 ， 安全技术及工程， 2012， 硕士

【摘要】 生物质的清洁可再生优势使其具有广阔的发展前景。但由于其含有大量碱金属,在燃烧过程中容易出现积灰结渣、聚团和腐蚀等问题,制约着生物质燃料的大规模应用。本文采用理论与实验相结合的方法,利用灰成分分析、X-射线衍射（XRD）分析、扫描电镜能谱分析（SEM/EDS）及电子探针X射线显微分析（EPMA）等测试手段对三种生物质秸秆（玉米秸秆、燕麦秸秆和水稻秸秆）燃烧过程的固态沉积物进行研究,深入地探讨了生物质燃烧的固态沉积物特性,旨在探明沉积物的形成机理。本文利用化学热力学平衡软件HSC对三种秸秆不同温度下燃烧的产物进行了预测,结果表明:K与Cl的反应先于Na;900℃后Cl可以从K₂SO₄和Na₂SO₄中获取碱金属增加气态物质总量;高的Na、Si含量会使温度低于800℃时得到的钠的生成物种类复杂,同时提高K的活性及产物复杂性;当硅含量相对较高时,在低于850℃的温度下固相中存在成较多碱金属硅铝酸盐。在管式沉降炉上研究了三种秸秆在不同燃烧时间、温度下燃烧过程的固态沉积特性。结果表明:三种生物质的沉积物量与原料的灰分、燃烧时间及燃烧温度都有密切关系,水稻秸秆沉积物量受时间变化的增加最大,燕麦秸秆燃烧沉积物量受温度影响的增加程度最大,沉积物硬度依次是玉米秸秆>燕麦秸秆>水稻秸秆,致密程度同此顺序,三种生物质沉积物的灰成分分析结果均以SiO2、CaO为主,Al₂O₃、K2_O和Na₂O等含量的差异影响着沉积物中化合物的种类和多样性;生物质秸秆燃烧沉积物的形成过程分累积粘结、“桥接”聚团,“交错搭架”这三种,这与秸秆粉末中的颗粒大小分布有关,沉积物中钾长石是支撑结构,沉积物外表的光滑是通过含碱金属的低熔点化合物等融化来实现,气态物质逐渐挥发在沉积物表面形成孔洞或气泡。孔隙的填充使沉积物变得致密。灰色关联度分析结果表明除燃料的碱金属含量外,温度是决定沉积物结渣特性的关键因子。更多还原

【Abstract】 Biomass have broad prospects due to its clean and renewable advantage. But the existence of alkali metals cause many problem during the biomass combustion. This paper combined the theory predict and experiment. Using chemical fractionation analysis, XRD, SEM/EDS and EPMA to analyse the characteristics of the solid phase deposition in different combustion temperature and time, which came from three different kinds biomass straws ( the straw of corn, oats and rice ). For a deep research on the mechanism of the deposition formation.This paper predicted the effects of temperature on the compounds variety on the base of chemical thermal equilibrium calculation. The results show that: K will first react with Cl, Cl can get alkali metals from K2SO4 and Na2SO4 to add gas phase substance after 900℃; Low content Na will cause little Na2SO4 formation, when the content is high, it will make the compounds below 800℃more complex and increase the activities of K; There are many solid phase compounds of aluminum borosilicate with alkali metals, high content Si will cause appearence of these compounds below 850℃.This investigation was carried out in the self-designed deposition furnace which examined the dynamic characteristics during three biomass straw combustion. The results showed that:The deposition weight was close connected with straw ash content, temperature and time, the increase of rice straw deposition weight was significantly affected by combustion time, and so did the combustion temperature on oat straw. The order of deposition hard is corn straw > oats straw > rice straw, the main part of chemical fractionation in all deposition are SiO2 and CaO, the content variety of other compounds like Al2O3, K2O and Na2O can effect crystalline forms and diversity in the deposition; there are three kinds process of deposition formation, agglutination, "bridge connection", "crisscross stand", respectively, and which of them was followed in the actual process depended on the particle size distribution in biomass fragments. Potassium feldspar is the supporting structure of deposition, and the oxide compounds of Al, Fe, Ca, Mg continued to fill the interspace and make the structure closed-grain. The formation process of compounds can be described as from simple to complex and part to whole, finally, elements evenly distributed.At last, the clinkering index of deposition was analyzed by gray association degree theory in different combustion temperature, time and alkali metals content. The results show that apart from alkali metals content, the temperature is the most important element.更多还原