【作者】 李子木；

【导师】 张香文；

【作者基本信息】 天津大学 ， 化学工艺， 2007， 硕士

【摘要】 本文模拟吸热燃料在使用时的超临界条件,建立了超临界反应装置以及分析反应管内壁积炭重量和分布的装置及方法,通过大量的试验确定了适宜的反应条件。以正十二烷,RP-3和自配仿JP-7为裂解原料在304#不锈钢一次性反应器中进行裂解积炭实验,从积炭量分布、平均积炭速率分布以及积炭形态等方面考察了每种燃料的积炭特性。并且回归出各种燃料的热裂解积炭反应宏观动力学方程。本文还在已有研究基础上考察了正十二烷和RP-3的氧化积炭及其规律。正十二烷和RP-3的氧化积炭随温度的升高而缓慢增多,在燃料中的自溶解氧(空气中饱和为约70ppm)消耗完毕时,氧化积炭量达到最大值。而后随着温度的进一步升高,氧化积炭量有所下降,并且在氧化反应和裂解反应的过渡区内维持在较少的水平。对数据回归得到了正十二烷和RP-3的氧化反应表观活化能分别为36.91kJ/mol和80.15kJ/mol,这说明RP-3的热氧化安定性是优于正十二烷的。燃料在超临界热裂解过程中形成的积炭主要有两种:无定形炭和纤维状炭。金属催化产生的纤维焦炭是积炭的主要来源。通过对各种燃料在超临界条件下的裂解积炭总体分析,得到了正十二烷、RP-3和仿JP-7各自裂解反应的表观活化能分别为260kJ/mol、285 kJ/mol和399 kJ/mol ,这样就得到了三种燃料的热安定性由高到低的顺序为仿JP-7>RP-3>正十二烷。单独分析纤维状炭,得到正十二烷、RP-3和仿JP-7的纤维状炭积炭的表观活化能分别为371 kJ/mol,402 kJ/mol和550 kJ/mol。结果表明生成纤维状炭的积炭反应需要在较高的温度下才能发生。更多还原

【Abstract】 Simulating engine system in the hypersonic aircraft, a set of continuous flow reactor was set up to evaluate coke formation from thermal cracking of endothemic fuel in supercritical conditions. Methods were also set up to determine coke amount and depositing rate. Suitable reacting conditions were confirmed by a set of tests. With n-dodecane, RP-3 and surrogate JP-7, thermal cracking experiments were carried on in 304 stainless steel tube. Analyzing curves of coke amount and depositing rate, deposition character of each fuel and three global kinetics equations were got.Thermal oxidation deposition of n-dodecane and RP-3 was invertigated. The thermal oxidation deposition of n-dodecane and RP-3 increase slowly when temperature rises, and reach the maximum when dissolving oxygen (exposed in air about 70ppm) was exhaisted. Then it reduces gradually with increase of temperature, and becomes stable at a value in the transition region. The apparent activation energy of RP-3 is 80.15kJ/mol and it is higher than that of n-dodecane 36.91kJ/mol, indicating a better performance of RP-3 in thermal stability.There are two kinds of deposition formed in supercritical thermal cracing: amorphous carbon and filamentous carbon. Filamentous carbon formed by the metal catalysis is the main source of the deposition in the thermal cracking regime. By the annlysis of total deposition, apparent activation energy of n-dodecane, RP-3 and surrogate JP-7 were 260kJ/mol, 285kJ/mol and 399kJ/mol, demonstrating an order of the thermal stabily from high to low: surrogate JP-7, RP-3, n-dodecane. The apparent activation energys obtained by the similar analysis in filamentous carbon deposition are 371 kJ/mol, 402 kJ/mol and 550 kJ/mol. Comparison of the two sets of apparent activation energies shows that filamentous carbon was formed at a higher temperature.更多还原