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题名	煤拔头半焦燃烧反应特性的研究
作者	仝晓波
学位类别	硕士
答辩日期	2009-05-22
授予单位	中国科学院过程工程研究所
授予地点	过程工程研究所
导师	宋文立
关键词	拔头半焦 燃烧特性 热分析 沉降炉
其他题名	Study on Combustion Characteristics of Char from Coal Topping Process
学位专业	化学工程
中文摘要	在煤拔头工艺条件下对煤进行快速热解，在得到油气等目的产物的同时也会产生大量的固体半焦。目前此拔头半焦的利用方式是直接送入到循环流化床锅炉中进行燃烧，其它用途较少。如果将煤拔头技术与电站粉煤燃烧锅炉相结合，即：将煤拔头工艺产生的半焦作为电站粉煤燃烧锅炉的燃料，则将进一步扩大煤拔头工艺的应用范围。 然而在燃煤机组运行的过程中，燃烧设备与燃料特性的相适应非常重要。鉴于此，本论文对大同烟煤拔头半焦的燃烧特性进行了深入研究，为煤拔头技术应用于电站粉煤锅炉燃烧发电提供理论基础。 首先，利用喷动载流床实验台模拟煤拔头工艺对煤进行快速热解，在550、650、750和850 ℃温度下，制备了三种粒度(0-145μm、0-198μm和0-245μm)大同烟煤的拔头半焦；对所得到的12种拔头半焦的组成进行了分析；使用热天平对原煤和拔头半焦的燃烧特性(着火温度、动力学参数以及燃烧燃烬情况)进行了分析，提出了一个无量纲综合燃烧指数，用以综合评价煤或焦样的着火、燃烧和燃烬性能；此外，测试了沉降炉内温度场的分布情况，对给料机进行了初步标定。利用沉降炉热态实验台模拟粉煤锅炉的实际燃烧工况做了初步的燃烧实验，并对实验数据进行了初步分析。 拔头半焦的组成和结构分析表明，拔头半焦的挥发份含量随热解温度的升高和气体停留时间的缩短而降低，燃料比热解温度和气体停留时间的缩短而升高。三种粒度原煤作对比，均以粒度为0-198μm的大同烟煤系列热解半焦的挥发份含量最高，燃料比值最低。随着原煤热解温度的升高和气体停留时间的缩短，煤中烃类支链和含氧结构的脱除程度增加，芳香环的缩聚程度变大，同时大分子碎片之间的聚合反应生成芳香性更高的半焦结构。 热天平实验结果表明，三种粒度大同烟煤系列拔头半焦的表观燃烧反应活化能和着火温度均高于原煤而低于阳泉无烟煤。其中，表观燃烧活化能约为1.7×105-2.9×105 J/mol。随着原煤热解温度的升高，拔头半焦的表观燃烧活化能和着火温度也升高。三个粒度原煤做对比，热解温度相同时，粒度为0-198μm大同烟煤系列拔头半焦的着火温度和表观燃烧活化能为最低。 提出了新的无量纲综合燃烧指数Z，用来表征煤样着火、燃烧和燃烬性能，该指数一方面能够合理的表征煤样的综合燃烧情况；另一方面因不受单位制的影响，适用性更广。Z值越大，煤样的综合燃烧反应性越好。拔头半焦的综合燃烧指数Z随着原煤热解温度的升高而降低。原煤热解温度相同时，三种粒度原煤拔头半焦比较，粒度为0-198 μm大同烟煤的系列拔头半焦的综合燃烧指数值最高，综合燃烧性能最佳。且粒度为0-198 μm的大同烟煤在550 ℃下所制得的拔头半焦的着火温度最低，表观燃烧活化能最低，综合燃烧指数Z值最高，综合燃烧性能最好。 空白实验工况下沉降炉反应器的温度场分布满足一般的工程需要（误差范围为5 %），符合实验要求。实验条件下，在给料机加一个搅拌电机可以实现连续均匀给料，能够实现1 g/min的给料需求。 沉降炉实验初步表明，根据烟气成分的变化情况可将煤在沉降炉内的燃烧过程分为三个区间：缓慢氧化区、高速氧化区和燃烬区。其中缓慢氧化区为反应器内距煤粉出口至465 mm以内的区间；高速氧化区为距煤粉出口465-468 mm的区间；燃烬区为距煤粉出口468 mm至700 mm的反应区间。初步实验证明，在温度设定为1100 ℃时0-198 μm大同烟煤的在沉降炉内的着火距离约为466 mm。
英文摘要	During the coal topping process, coal is fast pyrolized to obtain oil and gas, meanwhile a large amount of solid char will also produced. At present, the coal topping process is integrated with the CFB boiler and the char is directly burned in the CFB furnace. If the coal topping process could be intergraded into the PC boiler power plant, the application of Coal Topping process will be significantly increased because majority of coal power plant in China use PC boiler. For coal boiler, it is very important that the fuel should be suitable to the equipment. In this paper, the combustion characteristics of Datong coal char from coal topping process is studied to provide some information for the combination of coal topping process with PC power production. First, different chars have been prepared with the spouted bed reactor at four pyrolysis temperatures (550, 650, 750 and 850 ℃), and 3 particle size groups (0-145μm, 0-198μm and 0-245μm) from Datong bituminous coal. The compositions of different chars are analysized. The combustion characteristics of the raw coal and its chars are studied with a thermo-gravimetric device. A new dimensionless combustion index Z has been proposed to describe the combustion behavior of coal and its char. Preliminary combustion experiments are also conducted with the drop-tube furnace (DTF). The composition analysis indicates that the volatile content and fuel ratio decreases with the pyrolysis temperature increasing. Among chars from 3 particle groups, the volatile content of char from 0-198 μm particle size coal group is the highest, and the fuel ratio is the lowest. With the pyrolysis temperature increasing, the removal of oxygen-containing structure is increasing, the degree of aromatic polycondensation is increased. Meanwhile the polymerization of macromolecular debris results higher aromatic char structure. Thermagravimetric (TG) analysis results show that most apparent combustion kinetic parameters of 3 particle size chars are between that of raw coal and Yangquan anthracite. The activation energy is between1.7×105-2.8×105 J/mol. Both ignition temperature and activation energy increases with the pyrolysis temperature increasing. Among chars from different raw coal particle size at the same pyrolysis temperature, the ignition temperature and the activation energy of ones from 0-198 μm particle raw coal size is the lowest. A new dimensionless combustion index Z has been proposed to describe the combustion behavior of coal and char. The index can reasonably characterize the coal combustion behavior, and also have broader applicability due to its dimensionless nature. The higher the Z value, the better the combustion behavior. For different chars, with the increasing pyrolysis temperature the combustion index Z is decreasing. Among chars from different raw coal particle size at the same pyrolysis temperature, Z value of char from 0-198 μm particle size raw coal is the highest. The ignition temperature and the apparent activation energy of the char from 0-198 μm particle size raw coal and 550 ℃ pyrolysis temperature is the lowest, Z value is the highest, among 12 different chars. For DTF reactor, the temperature distribution along the furnace can meet the general experimental needs (Error limit of 5%). The addition of a stirring motor to the feeder could achieve a continuous and uniform feeding situation, and meet the expected demand of 1g/min feeding rate. Preliminary combustion-experiments with DTF unit indicate that, the combustion process can be divided into 3 ranges: slow oxidation zone, high-speed oxidation zone and burnout zone, according to the CO2 concentration along the furnace. In the DTF, from coal exit to the position of 465 mm belongs to slow oxidation zone; from position 465 mm to 468 mm is the high-speed oxidation zone, and from position 468 mm to 700 mm belongs to the burnout zone. The ignition distance of Datong bituminous coal in DTF is about 466 mm at 1100 ℃ temperature setting.
语种	中文
公开日期	2013-09-16
页码	116
内容类型	学位论文
源URL	[http://ir.ipe.ac.cn/handle/122111/1276]
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	仝晓波. 煤拔头半焦燃烧反应特性的研究[D]. 过程工程研究所. 中国科学院过程工程研究所. 2009.

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