【作者】 叶贻杰；

【导师】 陈汉平；

【作者基本信息】 华中科技大学 ， 热能工程， 2007， 硕士

【摘要】 生物质能作为世界一次能源消费中的第四大能源资源,在历史长河中与人类生活密切相关,是唯一可存储和运输的可再生能源,在人类未来的能源系统中也将占有重要地位。然而,在实际的生物质燃烧、气化利用过程中,结渣现象已经频繁地发生,成为重大的运行问题之一。而结渣的问题,通常是与燃料灰的特性密切相关。因此,为了高效地利用生物质能,需要充分掌握生物质灰的各种性质,而且从试验和理论的层面探讨其相应的结渣机理。本文选取木屑、花生壳、谷壳和稻秸四种常见的生物质,分别在高温和低温下进行灰化,探讨了灰分量随灰化温度和灰化时间变化的关系,并利用带有X射线能谱仪的扫描电镜(EDX-SEM)对不同生物质灰中的主要氧化物成分、无机元素组成以及灰的微观形态进行了研究,还测试分析了每种生物质的熔融性。结果表明:硅和钙在生物质的无机元素总构成中占有最大的比例,其中K2O、Na2O的含量也较高,由此导致其熔融温度低。在灰特性研究的基础上,为了深入理解生物质利用过程中内在的结渣机理,以采取有效的预防措施,从与结渣现象密切相关的影响因素以及床结渣的物理化学特性两个方面,对生物质流化床燃烧的结渣问题进行了理论分析。并初步探讨了SiO2和Al2O3对生物质灰熔融性的影响,二者配比的增加降低了混合物的熔融性,且温度水平对Al2O3混合物熔融影响较小。进一步,根据对实验数据的处理,求解了生物质的各种常规结渣指标,并采用模糊评判的方法判别出不同生物质的结渣倾向。通过本文对生物质灰特性及其结渣机理的分析研究,为形成生物质基本性质分析的系统理论提供了一定的参考,加深了对生物质灰多方面特性的认识,也有助于今后关于生物质结渣的综合研究。更多还原

【Abstract】 The amount of biomass resource is the fourth in the once energy consumption globally. Biomass plays critical role to human life. It is the only storable and transportable reproducing energy and is an important alternative to energy consumption in the future. However, agglomeration is displayed frequently during the practical biomass combustion and gasification, and disturbs the normal operation. The agglomeration is affected by the characteristics of biomass ash. Hence, it is quite necessary to understand the characteristics of biomass ash, and explore corresponding agglomeration mechanism from the experimental and theoretical respects, so that it can be utilized efficiently.In this study, four typical biomass resources: wood dust, peanut shell, rice shell and rice stem, were selected to make ash in high and low temperature, respectively, to explore the relationship of ash weight with combustion temperature and time. And then the main oxide component, inorganic element composition and microscopic morphologies were analyzed via a scanning electron microscope (SEM) with energy dispersive X-ray analysis (EDX). In addition, the melt point of every biomass ash was measured and analyzed. The results showed that the proportion of silicon and calcium was the most, and the content of K2O and Na2O was also quite high, resulting in the melt point low.To understand the inherent agglomeration mechanism during biomass application and approach preventive measures effectively, the agglomeration problem was analyzed from two aspects of influencing factors related to agglomeration phenomenon and physical and chemical characteristics of bed agglomeration during biomass fluidized-bed combustion. Then the effects of SiO2 and Al2O3 on biomass ash melting characteristic was explored, the melt degree of compound decreased with amount of addition rising, and the influence of temperature was weak for Al2O3. Finally, with the help of dealing with experiment data, the common agglomeration quotient was calculated to determine the agglomeration degree of different biomass through fuzzy mathematics.This thesis supplies essential reference for the forming of biomass characteristics theory, and important aspects of biomass ash characteristics are understood profoundly. It is beneficial for the synthetic researches of biomass agglomeration in the future.更多还原