高分子废弃物在热等离子体中的降解与转换研究

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	高分子废弃物在热等离子体中的降解与转换研究
其他题名	Pyrolysis of Macromolecular Waste in Nitrogen Thermal Plasma
	唐兰
导师	吴创之
	2003
学位授予单位	中国科学院广州能源研究所
学位授予地点	中国科学院广州能源研究所
学位名称	硕士
学位专业	热能工程
摘要	等离子态是物质的第四态。高分子废弃物在等离子体作用下可以生成氢气和其它碳氢化合物。氢气是一种优质无污染的气体燃料，可以用于燃料电池，也广泛应用于化学工业、冶金工业、半导体工业等。当热解过程中加入水蒸气时，还可以产生合成气，进一步扩大产物的应用范围。本论文考察温度范围及反应初始组成条件对产物分布的影响，在实验中选取了两种高分子废弃物，塑料聚丙烯（PP）与废轮胎作为实验原料。实验中所用直流电弧等离子体发生器最大功率62.5千瓦，反应器内径50mm，高1000mm。首先进行了塑料PP的等离子体热解实验，通过一系列实验得到了粒径、输入功率、进料速率等操作条件对气、固相产物分布及成分组成的影响。在输入功率35．2kvA，进料速率609／min的工况下，H2气体产物中所占比例可以达到18％，C2H2可达到5％。为改善气体品质，扩大其应用范围，反应过程中加入与进料量等质量的水蒸气，结果显示，H2和CO之和在气体产物中占40％，在该工况下，获得最高转化率％％及气体产率2160 ml／g。实验结果表明，等离子体热解是进行废塑料一能量回收的有效途径。然后，进行了废轮胎的等离子体热解，其主要气体产物经色谱分析为H2，CO，CH4，C2H2等。同样'根据废塑料的实验结果，我们考虑了各种操作对产物的影响。在本论文实验条件下，H2和CO产量之和可以达到38.3％。热解使轮胎中的硫分布于气体产物和固体产物中，其分布受输入功率、进料速率、水蒸气参与反应、白云石吸收等影响。在本论文实验条件下，固体产物中硫含量最高可以达到轮胎中硫总量的99％。最后，分析了废轮胎的等离子体热解固体产物热解碳黑（CBp）的用途，在实验中，固体产物产率约占60％，其中包括轮胎中的配料碳黑、某些金属氧化物及碳化物。热解碳黑CBp的特征值是轮胎中添加的各种商业碳黑特征值的平均值。采用SEM观测了CBp的表面形貌。对CBp采用XPS进行表面化学性质分析，采用NMR、XRD等手段对其内部化学性质进行了分析。实验结果显示，CBp具有与商业碳黑很相似的特性，经过进一步处理可以作为碳黑替代物使用。
其他摘要	Plasma is the fourth state of matter. Pyrolysis of macromolecular waste in nitrogen plasma can produce hydrogen and other hydrocarbons. Hydrogen-rich gas is useful in several applications: Distributed, low-pollution electricity generation from fuel cells; For chemical applications such as hydrogenation, metallurgical process; For the semiconductor industry. By injecting water steam in the process, syngas can be produced. In order to find the temperature range and initial reactant for the product distribution, two kinds of macromolecular waste of polypropylene (PP) and used old tires have been used in the experiments. The plasma reactor has a D.C. arc nitrogen plasma generator with a maximum electric power input 62.5 kVA and a reaction chamber of 50 mm inner diameter and 1000 mm height. Plasma pyrolysis of polypropylene has been studied for the purpose of converting waste plastics into gaseous fuel and useful chemicals. The results of a series of experiments have shown that under our optimum experimental conditions of power input 35.2kVA, feed rate 60g/min, the concentration of hydrogen in the gaseous product can reach up to 18%, and acetylene up to 5%. Steam injection was introduced for improving the product quality and extending the application range; by water steam injection, the sum of hydrogen and carbon monoxide can reach up to 40% in the gaseous product, while the decrease of acetylene concentration was slight. A solid conversion of 96% and gas productivity of 2160 ml/g were achieved. The results indicate that plasma assisted thermally decomposition of polypropylene may be a useful way for recovering energy and useful chemicals of waste plastics. Secondly, thermal plasma pyrolysis of used old tires for recovering energy has been performed in a nitrogen plasma reactor. The main gaseous products were identified by chromatography as H2, CO, CH4, C2H2 and so on. From a series of statistically designed experiments, the effects of the process parameters of thermal plasma pyrolysis have been investigated. Under our experimental condition, the yield of H2 and CO can reach up to 38.3% in the gas product. The pyrolysis leads to distribution of sulfur compounds in pyrolysis gas and char generated during the process. The transformation of sulfur during thermal plasma pyrolysis of used tires was studied. Global and sulfur mass balances were performed. It was found that distribution of total sulfur in tires pyrolysis product is basically affected by input power, feed rate, addition of steam and acceptor to the pyrolysis; maximum deposited sulfur in the solid residue can reach up to 99%. Lastly, the potential use of the solid residue as pyrolysis carbon black (CBP) has been discussed. In the present work, the yield of CBP and other solid residue was approximately 60%. The CBP had properties that were an average of those of the various grades carbon black added during tires manufacture. The surface chemistry of CBP was analyzed by X-ray photoelectron spectroscopy (XPS), bulk chemistry of CBP was analyzed by XRD and NMR. It was found that CBP surface chemistry is similar to those of commercial carbon blacks. Therefore, CBP has the potential to replace commercial carbon blacks in certain rubber applications.
页数	119
语种	中文
文献类型	学位论文
条目标识符	http://ir.giec.ac.cn/handle/344007/3873
专题	中国科学院广州能源研究所
推荐引用方式 GB/T 7714	唐兰. 高分子废弃物在热等离子体中的降解与转换研究[D]. 中国科学院广州能源研究所. 中国科学院广州能源研究所,2003.

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