【作者】 朱玉红；

【导师】 米镇涛；

【作者基本信息】 天津大学 ， 化学工艺， 2007， 硕士

【摘要】 本研究建立了一套模拟航空发动机系统的连续流动超临界热裂解装置,以国产航空燃料RP-3为裂解原料在304#不锈钢一次性反应器中进行裂解生焦实验,分别从焦炭总量和焦炭分布,SEM形貌,程序升温氧化TPO曲线,裂解气和裂解液诸方面分析了燃料裂解中焦炭的形成过程以及三种抑焦技术的抑焦效果。RP-3燃料在超临界热裂解过程中形成的沉积物类型有三种:分别为富氢吸附碳、无定形炭和纤维焦炭;金属催化产生的纤维焦炭是沉积物的主要来源;超临界流体对焦炭前体和已形成的固体焦炭有很强的萃取及溶解能力,可携带90%以上的焦炭;研究表明焦炭生成同时造成金属渗碳情况的发生。结焦抑制剂二苄基二硒醚与金属管壁反应生成硒化铁抑制金属催化生焦过程;与空白燃料相比,燃料中添加质量分数为100ppm的添加剂可抑制49.6%的焦炭生成,并使致密的焦炭颗粒变得疏松;二苄基二硒醚没有改变燃料裂解气的气相组成,但抑制了燃料裂解率,添加100ppm二苄基二硒醚后燃料的裂解气体产出率为空白燃料的77.9%;添加剂的加入使裂解液中的多环芳烃含量有所降低。对反应管内壁用酸性溶液进行钝化处理,形成薄而致密的钝化膜可抑制金属催化生焦。与未处理管相比,管壁钝化可以抑制99%的焦炭生成,并可削弱温度对焦炭生成量的影响,且抑焦效果持续有效;SEM和TPO分析钝化管沉积有极少量焦炭,焦炭层厚度很薄;钝化膜不改变裂解气的气相组成,其裂解气气体产出率为未处理管中燃料裂解气体的85%;裂解液中没有检测到三环以上芳烃化合物的存在。在燃料中添加供氢剂苯甲醇,并用硝酸溶液对管壁进行钝化处理,可以同时达到抑制金属催化生焦和抑制自由基聚合生焦的目的。与钝化管中燃料裂解的结果相比,质量分数为0.5%的苯甲醇可以在管壁钝化的基础上进一步抑制15%的焦炭生成,裂解气产出率为钝化管中燃料裂解气的83.3%,裂解气气相组成没有发生变化;供氢剂的加入抑制了多环芳烃的生成,使黑色粘稠的裂解液变得更加清澈透明。更多还原

【Abstract】 Carbon deposition from jet fuel on metal surfaces will create problems for the operation of future aircraft. A set of continuous flow reactor which simulates engine system in hypersonic aircraft was set up to evaluate coke formation from thermal cracking of jet fuel RP-3 under supercritical conditions and three methods suppressing deposits build up. Solid deposits collected on the substrates were examined by scanning electron microscopy(SEM), energy-dispersive X-ray spectroscopy(EDS), and temperature programmed oxidation(TPO) and cracking products was analyzed.There are three different species including chemisorbed carbon, amorphous carbon and filamentous coke in the solid deposits which forming from thermal cracking of RP-3 jet fuel; Beyond 90% of coke deposits are carried away by supercritical fluid which have highly capabilities of extraction for coke precursors and dissolution for coke deposits. Coke formation results carburetion on alloy.The coke inhibitor, dibenzyldiselenides, could suppress filamentous coke by forming thermal stable M2Se over the stainless steel surface at the higher temperature. It is found that with the addition of 100ppm dibenzyl diselenides the total coke deposits were reduced by 49.6%, and yields of gas was reduced by 20% without significant composition variation change. The passivation of metal surface could suppress filamentous coke by forming passivation film. Beyond 98% of coke deposits was decreased and influence of temperature to coke formation are weakened by surface passivation, which the ability of coke inhibition are durative; The distribution of gas products produced from passive reactor was not changed , but the 14.47% of gas yields was decreased by passive film. Hydrogen donors, BzOH was added into fuel while reactor metal surface was passived to suppress amorphous carbon and filamentous coke synchronously. Comparation to the passivation film, the addition of 0.5% BzOH could reduce the 15% of coke deposition amounts and the yields of gas was reduced by 16% without significant composition variation change. The three coke inhibition methods discussed above all suppressed the coke precursors forming.更多还原