| Energy as an important material basis of people’s daily life, social progress and economic development, with the over exploitation of people, oil, coal, natural gas and other resource becomes more and more scarce, even in the mid twenty-first Century there will be a part of fossil fuel depletion. Furthermore, the unreasonable exploitation of energy resources using will cause a series of environmental pollution problems. Especially, in our country, not only the consumption of energy is huge, and the rate of energy utilization is low, the consumption structure of energy is imbalance, which makes serious environmental pollution. According to the statistic, at present, the total emissions of carbon dioxide in China take the second part in the world, and it’s only lower than American, sulfur dioxide emissions ranks first in the world, and 70 percent of carbon dioxide emissions,90 percent of sulfur dioxide emissions,66.7 percent of nitrogen oxide emissions are from coal-fired. In order to alleviate the energy crisis and environment pollution, we start looking for the development and utilization of new energy. Biomass as a clean non-polluting source of energy has been widely accepted by many countries, particularly in the pyrolysis of biomass into bio-fuels and other liquid fuels, which are widely used in Western countries. However, due to the difficulty of bio-fuel’s combustion, the combustion of bio-fuel with the conventional combustion equipment will bring many adverse effects, the lack of dedicated combustion equipment, not only hinder the development of biomass fuel cracking technology, and more impact on the reasonable using of biomass. Therefore, based on the National 863 project "skewed slot low energy precision controlled heating of biomass fast pyrolysis for bio oil and mixed emulsion of new technology" as the basis,collection and access to a large number of documents, information at home and abroad on the fuel combustion machine, and has carried on the thorough study and research, energy saving and emission reduction, the biological fuel to reduce production costs for a full, for the purpose ofatomization combustion, and associated with the previous research results and experience of combustion engine combustion, the design of a suitable biological fuel, has the significant practical significance, economic significance of energy security, environmental protectionsignificance and the significance of sustainable development.Through the experiment of biological fuel properties, we investigated the biological fuel’s viscosity, flash point, density, moisture content and other characteristics, and compared it with the diesel oil in characteristics, finally obtained the particularity and the flammability of the bio-fuel. Based on the experiment of bio-fuel performance, we use the Zeldovich theory of combustion and the thermal theory to analyze the combustion process, combustion theory, the flame propagation theory of the biological fuel, simultaneously analyzed the heat of combustion kinetics of the bio-fuel, in order to establish the kinetic mechanism of the characteristics of biological fuel volatilization and combustion section, to provide a theoretical basis for the research on combustion characteristics of bio oil.Research on the combustion mode and the factors affecting the heating rate of biological fuel, and analyzed the parameters atomization characteristics of viscosity, surface tension, gas-liquid mass flow, density and nozzle structure that affect their biological fuel. Meanwhile, theoretical calculated the bio oil combustion air volume required for the theory and the actual amount of air, we got the actual air’s volume of V should be 6.37 Nm3/kg, what provide the preliminary preparations for the subsequent structural design.Through the theoretically calculated and designed the structure of bio-fuel burner, especially focused on the design of the fuel supply system, air supply system, the structure of nozzle, and made sure the nozzle diameter of the bio-fuel burner is 4.59mm, the atomization angle is 98 degrees, and equipped four nozzles for this bio-fuel burner the atomization of the fuel injector at the same time, on condition that we have to preheat the bio-fuel to 70 degrees before combustion.Numerical simulated the biological fuel burner’s atomization and combustion processes using FLUENT fluid analysis software. Among them, including the establishment of mathematical models, meshing, boundary conditions, iterative parameter settings, etc. By the results of simulation analysis show that:atomized fuel is uniform particle size, particle size is moderate, mist speeds up to 46m/s, and the temperature of the oil mist sprayed by the nozzle is up to 473K, can shorten the pre-combustion of bio-fuels and meet the design requirements. The temperature of bio fuel is up to 2500K after combustion, having achieved industrial required temperature. Meanwhile, bio fuel combustion exists negative pressure-3.87Pa in the recirculation zone, ensure the bio fuel and two time atomization air fully mixed, so as to provide sufficient oxygen for biological fuel complete combustion, at the same time, the combustion efficiency is improved.The paper have experiment the bio-fuel burner prototype of independent design, determined the nozzle structure、injection pressure by spraying performance experiment, and determined the optimal nozzle diameter, injection pressure and fuel temperature according to the effect of bio fuel temperature on spray process. By bio-fuel burner combustion experiments, analyzed the impact of the cyclone intensity on the axial velocity and the influence of excess air coefficient, different air distribution, different amount of fuel on the effect of bio fuel combustion, ultimately determined the excess air coefficient is 1.2, with air volume is 0.48m3/s, the amount of fuel is 156.25kg/h is the optimal condition, under the condition, bio-fuel combustion is the best, the combustion temperature can reach about 2550K, which can satisfy the temperature requirements for industrial application. |
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