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题名	褐煤热预处理及预处理后热解研究
作者	董鹏伟
学位类别	硕士
答辩日期	2012-05-25
授予单位	中国科学院研究生院
导师	许光文 ;    高士秋
关键词	褐煤 热预处理 热解 焦油 过热蒸汽
其他题名	Thermal pretreatment and subsequent pyrolysis of lignite
学位专业	化学工程
中文摘要	热解是一种从煤中直接获取低碳燃料及高值化学品的温和转化工艺。现有热解技术存在焦油产品收率低且焦油中的重质沥青质组分含量高的缺点，给装置的连续运行及油品的深加工带来问题，因而在工业上还没有得到广泛应用。对热解反应前的煤进行预处理，能够改善煤中结构、改变其元素配比，进而可能调控热解油品收率及品质。其中热预处理能够利用常见低品位热源，在低于热解温度条件下的不同气氛中，对煤样的结构及组成进行一定的改变，使其热解行为发生变化。针对中国储量多、含水高的褐煤，热预处理可同时实现其干燥脱水，还可充分利用热烟气及过热水蒸汽等低品位热源，因而具有极高的实际工业可应用性。 本论文采用固定床反应器研究了不同气氛、温度条件下热预处理内蒙胜利褐煤对煤元素组成和官能团结构的改变，表明：随着预处理温度的升高，煤中气体释放量增加，释出气体的主要成分为CO2。含O2气氛下的预处理过程中煤释放的气体量比惰性气氛下要高。与原煤相比，热预处理后煤中羟基的红外吸收强度减弱，芳香氢与脂肪氢的红外吸收强度比减少，脂肪氢的相对含量增加，表明煤中的氢源分布情况发生了改变。原煤的表面吸附能力较强，经过热预处理后，受干燥及煤中部分挥发分逸出的影响，中孔数量减少而微孔数量相对增多。预处理后的煤在同一反应器中直接升温至600 ℃发生原位热解。与未经处理的煤热解相比，N2、N2＋O2、CO2气氛下热预处理后热解水收率下降，热解气收率增加，热解气中CO2含量增高，从而导致热值下降。过热水蒸汽热预处理后，焦油质量收率提高约3～4个百分点。热解焦油组成的变化与预处理气氛和温度密切相关，过热水蒸汽在200 ℃时的预处理容易使得焦油中轻质组分的含量（沸点低于360 ℃的馏分）比原煤热解焦油提高了约27个百分点。水蒸汽与模拟烟气的混合气氛下在200 ℃及250 ℃预处理后，其热解焦油中轻油和酚油含量分别提高约60和42个百分点。
英文摘要	Pyrolysis provides a mild conversion of coal to obtain directly low carbon fuels and valuable chemical products. There are many coal pyrolysis technologies but none is in practical application due to possible the low tar yield and too high fraction of heavy pitch in the tar. The pitch would hinder the smooth running of the pyrolysis process and the downstream treatment of the tar. Pretreatment of coal in advance pyrolysis may change the structure and alter its element composition of the coal to infleunce the coal pyrolysis behavior. Thermal pretreatment with low-grade heat source may vary the pyrolysis behavior by altering the funtional groups and compositions of coal at temperatures lower than the pyrolysis temperature. For lignite containing high moisture content, the thermal pretreatment can implement as well the liginite drying or dewatering by using the low-rank heat in hot flue gas or overheated steam as the heat source. This study investigated the impact of pretreatment on coal properties and subsequent pyrolysis behavior in a fixed bed reactor for Shengli lignite. The results showed that the amount of gas released from coal in the treatment increased with raising the pretreatment temperature and CO2 is the major component of the released gas. More gas was released when pretreating the lignite with O2-containing gas. In comparison with raw coal, the thermally pretreated coal had lower content of hydroxyl group and lower ratio of aromatic-H to aliphatic-H. The latter indicated that the thermal pretreatment changed the distribution of H in coal. The surface absorption capability of raw coal is stronger than the thermally pretreated coal. The number of micropores increased, whereas that of mesopores decreased due to the release of volatile matters from coal in pretreatment. The pretreated coal was heated up to 600 ℃ in the same reactor for implement the in-situ pyrolysis. The yield of pyrolysis water was lowered by the thermal pretreatment in all tested atmospheres including N2, N2+O2 and CO2. The pretreatment caused also a higher CO2 content in the pyrolysis gas, which thus lowered the heating value of the gas. Pretreating the coal in superheated steam increased the tar yield by 3-4 weight percentage points, and the composition of the tar varied with the atmosphere and temperature of the pretreatment. While the light fraction (with boiling points below 360 ℃) increased by 27 weight percentage points for pretreatment in 200℃-steam, the pretreatments at 200 and 250 ℃ in the mixture of steam and simulated flue gas raised the fractions of light oil and phenol oil in tar by 60 and 42 weight percentage points, respectively.
语种	中文
公开日期	2013-09-25
内容类型	学位论文
源URL	[http://ir.ipe.ac.cn/handle/122111/1825]
专题	过程工程研究所_研究所（批量导入）
推荐引用方式 GB/T 7714	董鹏伟. 褐煤热预处理及预处理后热解研究[D]. 中国科学院研究生院. 2012.

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