Experimental Study Of Combusition Kinetics And Fuel Characteristics Of Biomass Tar

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.