【作者】 武斌；

【导师】 米杰；

【作者基本信息】 太原理工大学 ， 化学工程与技术， 2018， 硕士

【摘要】 碳纳米管材料因其良好的性能而广受关注。然而,受限于碳纳米管的合成成本使之不能广受应用,燃烧法合成碳纳米管的出现,使得低成本、大规模、连续地合成碳纳米管成为可能。本文通过模拟计算的方法研究了预混合燃烧器的结构对火焰形态的影响,选取了最优化的预混合燃烧器结构进行实验,并分析了影响合成碳纳米管的主要因素,得到了合成碳纳米管的最佳工艺条件。本文以数值模拟的方法,利用COMSOL软件对不同结构下燃烧器模型进行计算,并将计算所得最佳结构的燃烧器安装搭建;利用CHEMKIN软件对不同条件下的预混火焰模拟计算,得到合成碳纳米管的最佳工况和取样高度。同时,将计算结果和实验数据相验证,证明了计算结果的合理性,为燃烧法合成碳纳米管提供一定的预测作用。具体结论如下:（1）通过COMSOL软件建立了进气孔径分别为26mm、4.0mm、3.0mm、2.0mm、1.0mm的三维燃烧器模型,由模型计算结果的对比分析可以得出,预混合燃烧器铜盘进气孔径的最佳值为1.0mm,在此结构下预混火焰的质量最高,同一水平面的温度、反应物浓度等条件最为均一。（2）在进气孔径为1.0mm的燃烧器模型中,计算了乙炔和氧气的当量比、进气流量、惰性气体含量、压力等对燃烧状态的影响。由此可得到合成碳纳米管时最佳火焰形态的工艺条件为:压力为6000[Pa],反应物当量比为1.4,进气流量为1.2*10^-5[m³/s],惰性气体氩气的含量为0.2。（3）在上述最佳火焰形态的工艺条件下,通过CHEMKIN软件计算了轴线上CO、H₂、C、OH、H、HCCO、HCO、CH₃等各中间组分的浓度分布,由此预测出最佳的取样高度在12mm¹6mm之间。（4）通过实验研究了火焰形态、当量比、进气流量、惰性气体的含量对合成过程中温度的影响,验证了三维燃烧模型的合理性,得出最优的实验工艺条件与模拟分析结果相一致。同时,实验证明了催化剂的存在对碳纳米管的合成有着关键性的作用。更多还原

【Abstract】 Carbon nanotubes are a remarkable material with many appealing properties.However,there are few synthesis techniques capable of producing nanotubes in large quantities at low-cost.The combustion synthesis method of carbon nanotubes makes it possible to synthesize carbon nanotubes at low-cost,large scale,and in a continuous manner.In this paper,the influence of the structure of the premixed burner on the flame morphology was studied.The main factors affecting the synthesis of carbon nanotubes were analyzed,and the optimal conditions for the synthesis of carbon nanotubes were obtained.In this paper,numerical simulation method is used to calculate the burner model with different structures using COMSOL software.The burner with the optimal structure is used to synthesize carbon nanotubes;the premixed flame under different conditions is calculated by CHEMKIN software to obtain the optimal conditions for the synthesis of carbon nanotubes.At the same time,the calculated results are verified with the experimental data,which proves the rationality of the calculation results and provides predictive function for the combustion synthesis method of carbon nanotubes.The specific conclusions are as follows:（1）These three-dimensional burner model with 26mm,4.0mm,3.0mm,2.0mm,and 1.0mm inlet nozzle diameters was built using COMSOL software.The comparison of model calculation results shows that the optimal diameter of premixed burner copper disc nozzle is1.0mm.Under this structure,the quality of premixed flame is the highest,and the conditions such as temperature and reactant concentration in the same level are the most uniform..（2）In the burner model with a 1.0 mm inlet diameter,the influence of the equivalence ratio of acetylene and oxygen,the flow rate,the inert gas content,and the pressure on the combustion state were calculated.The process conditions for optimum flame morphology in the synthesis of carbon nanotubes are:pressure is 6000[Pa],reactant equivalent ratio is 1.4,inlet air flow is1.2*10^-5[m³/s],the inert gas is argon and the content of argon is 0.2.（3）Under the above-mentioned process conditions of optimum flame morphology,the concentration distributions of CO,H₂,C,OH,H,HCCO,HCO,CH₃ and other intermediate components on the axis are calculated by the CHEMKIN software,thereby the best sampling height is between12mm¹6mm.（4）The influence of flame morphology,equivalence ratio,inlet flow rate and inert gas content on the temperature of the synthesis process were studied through experiments,and the rationality of the three-dimensional combustion model is verified,and the optimal experimental process conditions and simulation analysis results is identical.Meanwhile,the experiments have shown that the catalyst is essential for the synthesis of carbon nanotubes.更多还原