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生物质焦油燃烧动力学及其燃料特性实验研究
Experimental Study of Combusition Kinetics and Fuel Characteristics of Biomass Tar
【作者】 张全国;
【导师】 沈胜强;
【作者基本信息】 大连理工大学 , 动力机械及工程, 2006, 博士
【摘要】 本文研究工作是国家十五“863”高技术研究计划项目(编号:2003AA514012)“生物质燃气焦油净化器研制”的部分研究内容,主要开展生物质焦油净化蒸馏、组成分析、燃料性质、动力学以及内燃机负荷及排放特性等实验研究,为生物质焦油替代石油燃料进行了有益的探索。研究工作取得以下主要结论:(1)根据生物质焦油蒸馏实验,本文提出了各试样不同温度段的确定范围,即﹤105℃、105℃~145℃、145℃~205℃和205℃~220℃,并定义和分析了各试样的燃料性质。(2)生物质焦油的可燃性与柴油及水的溶解性有直接关系,即与柴油不能够互溶、与水互溶的试样具有不可燃特性,与柴油能够互溶、与水不溶的试样都具有直接可燃特性。(3)通过生物质焦油的可燃特性实验,发现试样二、四没有闪点,不具备可燃性;而试样一、三、五、六均存在闪点,具有一定的可燃性,且蒸馏温度越高,闪点也越高。试样一、三、五、六与柴油的化学成分比较接近,均具有碳氢含量高,氧含量低等特点,可以作为液体燃料使用。试样二和试样四中芳香族化合物含量很低,不具备液体燃料的使用价值,但是可作为化工原料。(4)不同气氛和升温速率下的燃烧动力学实验结果表明:生物质焦油、试样一、试样三、试样五、试样六、试样一、三、五混合液以及它们与0#柴油的混合液都具有挥发份含量高、挥发特性强、着火温度低、燃烧比较稳定、燃烧后灰分很少等特点,具备液体燃料的基本性质,可作为常规能源的替代燃料使用。(5)本文根据燃烧实验数据进行了动力学参数的回归分析,拟合结果表明生物质焦油燃烧过程可在不同温度区间用一级动力学模型来反映,并得出低温区间的活化能较低,高温区间的活化能较大。(6)本文利用不同比例混合油在内燃机上燃烧实验结果表明:混合油均具有良好的动力性、经济性和排放性。0号柴油与生物质焦油试样按9:1比例配置的混合油要比8:2时节油效果显著,不同比例的混合油均具有CO2减排显著、尾气排放烟度和CO降低明显等优点,有效减少了单一0号柴油燃烧时对环境污染的影响。
【Abstract】 This paper is focused on partial content of Development of Biomass Gas Tar Purifier , a“863”high-tech research program (No.:2003AA514012) in National Tenth Five-Year. It mainly involves experimental studies of biomass tar purification and distillation, composition analysis, fuel performance, dynamics as well as load and emission characteristics of internal combustion engine. A helpful exploration for substitution of petroleum fuel by biomass tar is made. Main conclusions are achieved as follows:(1) According to biomass tar distillation test, this paper gives specific range of different temperature interval for each test specimen, i.e. up to 105℃, 105℃to 145℃, 145℃to 205℃and 205℃to 220℃. This paper also provides definition and analysis of fuel performance for each test specimen.(2) The flammability of the biomass tar has a direct relation with the solubility of diesel oil and water. Test specimens that are mutually insoluble in the oil and soluble in the water have noncombustible property, and test specimens that are mutually soluble in the oil but insoluble in the water have direct combustible property.(3) From combustibility test for biomass tar, Specimens 2 and 4 are found noncombustible without flash points, while Specimens 1, 3, 5, and 6 are found combustible with flash points. In addition, the flash point will be higher with the increase of distillation temperature. Chemical compositions of Specimena 1, 3, 5, and 6 are similar with those of the oil, with high carbon and hydrogen content and low oxygen content. The compositions can be used as liquid fuel. With a very low content of aromatic compounds, Specimens 2 and 4 have no value in use of liquid fuel, but they can be used as chemical materials.(4) Results of combustion dynamics experiments under different atmospherea and temperature-rise rates demonstrate that, biomass tar, Specimen 1, Specimen 3, Specimen 5, Specimen 6, mixture of Specimens 1, 3 and 5, as well as the mixture of them and 0# diesel oil possess the features such as high volatile content, strong volatility, low ignition temperature, relatively stable combustion, and very low ash content after combustion, etc. They have basic nature of liquid fuel, and can be used as alternative fuel for conventional energy.(5) Regression analysis for dynamical parameters has been conducted in the paper according to the data from combustion experiments. The fitting results demonstrate that the combustion process of biomass tar can be reflected by the first-order dynamic model in different temperature intevals. Also it is concluded that the activation energy of low temperature interval is relatively low and that of high temperature interval is relatively high.(6) Results of the combustion test performed in internal combustion engine with oil mixture of different proportion demonstrate that all of the oil mixtures have good power, economical efficiency and emission performance. The oil mixture of 0# diesel oil and biomass tar specimens with the ratio of 9:1 has a more significant fuel-saving effect than that of oil mixture with the ratio of 8:2. Oil mixtures with different ratios possess advantages such as significant reduction of CO2 emission, as well as obvious reduction of exhaust emission intensity and CO content, effectively reducing the pollution effect on environment in case of the combustion of single 0# diesel oil.
【Key words】 Biomass Tar; Purification; Distillation; Fuel Characteristics; Combustion Dynamics; Internal Combustion Engine Test;