多种生物质热解特性对比分析毕业论文
2022-01-09 18:00:37
论文总字数:30597字
摘 要
随着农业产能的不断膨胀,生物质固体废弃物的产量也在逐年攀升,传统处理方法很可能造成潜在的空气或水体污染,且是对资源的极大浪费。因此,寻求何种有效方式使生物质废弃物无害化、资源化,成为环境污染治理中迫切需要解决的问题。生物质热解技术排放较低,对于生物质废弃物做到资源化利用,这一手段由此在世界范围内引起广泛关注。
由于生物质成分的复杂性和种类的丰富性。在其热解过程中,其反应行为依生物质种类不同有显著的差异。本文对木屑、棉花杆、花生杆和小麦秸秆等多种生物质开展元素分析与工业分析,采用同步热分析手段对上述各类生物质的进行了多次热解实验。以对比不同种类生物质在相同热解条件下热分解行为的不同。
基于CoatsRedfern积分法和各种反应机理,计算了生物质热解的动力学参数。对应不同反应机理对CoatsRedfern积分法的影响计算四种生物质的热解参数建立动力学模型研究了生物质组分对热解行为的影响。
区分了生物质分解三个阶段,着重研究对于热解过程的影响最显著的挥发分析出过程。发现生物质中中性洗涤剂溶解物NDS的存在容易使生物质分解早期出现失重高峰,纤维素和半纤维素的含量越高,则早期的平均活化能越高。木质素含量越大,最优热解温度越高,此时出现的最高热解速率越大,主失重峰越窄且深,生物质有机会在更短的时间内完成快速分解。
关键词:生物质 热解 动力学 同步热分析
Comparison of pyrolysis performance of various typical biomass
ABSTRACT
With the continuous expansion of agricultural production capacity, the output of biomass solid waste is also increasing year by year. Traditional treatment methods are likely to cause potential air or water pollution, and it is a great waste of resources. it is a urgenta request be solved quickly to detoxify and resource biomass waste and find an effective way. Biomass pyrolysis technology has a low emission, and the utilization of biomass waste is resource-based, which has aroused widespread concern in the world.
Because of the complexity and variety of biomass components. In the process of pyrolysis, the reaction behavior is significantly different according to the species of biomass. In this paper, sawdust, cotton wool, peanut straw, straw and other biomass were analyzed preliminarily and industrially.In order to compare the thermal decomposition behavior of different kinds of biomass under the same pyrolysis conditions.
By using coats Redfern integration method and selecting different mechanism functions, four kinds of kinetic parameters of biomass pyrolysis were calculated. On This Basis, the Kinetic model of biomass pyrolysis was established, and here biomass-components were studied
Three stages of biomass decomposition were distinguished, and the volatilization process which had the most significant influence on the pyrolysis process was studied. It was found that the presence of neutral detergent solution NDS in biomass could easily lead to the peak of weight loss in the early stage of biomass decomposition. The higher the content of cellulose and hemicellulose, the higher the average activation energy in the early stage. The higher the lignin content, the higher the optimal pyrolysis temperature, the higher the maximum pyrolysis rate, the narrower and deeper the main weight loss peak, and the biomass has the opportunity to complete rapid decomposition in a shorter time.
Key words: Biomass;Pyrolysis; Kinetic; Synchronous thermal analysis
目 录
摘 要 I
ABSTRACT II
目 录 III
第一章 绪 论 1
1.1 课题背景 1
1.2 生物质固废资源化方法和应用 2
1.2.1生物质废弃物来源 2
1.2.2处理方法 2
1.3影响生物质热解的条件 5
1.4 本文的研究内容 9
第二章 实验原料理化特性分析 11
2.1 原料来源和预处理 11
2.2 实验仪器及分析方法 11
2.2.1 工业分析 11
2.2.2 元素分析 12
2.2.3 生物质成分分析 12
2.3 实验结果与分析 13
2.4 本章小结 15
第三章 生物质热解特性研究 17
3.1 实验流程 17
3.2 分析方法 17
3.3 实验结果与分析 17
3.3.1花生杆生物质热解 18
3.3.2麦秆生物质单独热解 19
3.3.3木屑生物质热解 19
3.3.4棉花杆热解 20
3.3.5四种生物质综合比较 21
3.4本章小结 23
第四章 热解过程的动力学特性与反应模型研究 25
4.1 前言 25
4.2 动力学条件和基本方程 25
4.3 热解动力学参数计算 26
4.4 实验结果与讨论 28
4.4.1花生杆单独热解拟合结果 28
4.4.2麦秆单独热解拟合结果 30
4.4.3棉花杆单独热解拟合结果 31
4.4.4木屑单独热解拟合结果 33
4.4.5 综合比较 34
4.5 本章小结 34
第五章 结论与展望 37
5.1 结论 37
5.2 展望 37
参考文献 39
第一章 绪 论
1.1 课题背景
生物质固体废弃物是随着我国经济的发展和社会的进步,广泛存在于农业生产中的一种固体废弃物。固体废物发展前景明朗,预期产量仍然大量增加,处理需求不容忽视。我国正面临建立大气碳热氧平衡的核算核查体系、实施碳热氧产品交易、探索创建零碳区域发展模式等节能减排改革的关键阶段,采取措施妥善处理生物质废弃物减少碳排放尤为重要。
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