【作者】 韦刘轲；

【导师】 贾志刚；

【作者基本信息】 北京化工大学 ， 化学工程， 2010， 硕士

【摘要】 乙烯裂解炉是乙烯装置的核心设备,而乙烯裂解技术是整个乙烯工业的关键技术之一。乙烯裂解炉内包括了复杂的流体流动、燃烧反应、裂解反应以及热量传递等过程。国内在乙烯裂解技术的设计和开发方面还比较落后,目前世界上仅有少数公司掌握生产乙烯的成套技术。因此,整个乙烯裂解炉内的传递与反应过程研究对于裂解炉的设计与优化有着重要的意义。本文利用了计算流体力学的方法,并以KTI公司的GK-V型乙烯裂解炉为研究对象,建立了乙烯裂解炉的数学模型,对裂解炉内的流动、传热与反应过程进行了研究。主要工作如下：1、建立了包含1组炉管的1／4裂解炉的模型,对炉膛和炉管中的流动、传热以及裂解反应进行了考察,并分析了炉膛与炉管中的耦合影响。研究表明,由于各裂解炉炉管在整个炉膛中的空间位置分布不同,造成了各炉管的传热不均匀,各炉管的受热差异又导致了管内的主要产物收率存在差异。炉管壁面热边界分布是由炉膛内的流动、传热与炉管内的流动与裂解反应影响共同造成的。2、建立了更符合实际情况的1／2裂解炉模型,对其流动、传热以及裂解反应进行了考察,分析了包括两组炉管的裂解炉模型的传热与裂解反应。研究发现,由于结构的非对称性,1／2裂解炉的炉膛内的流动和传热情况与1／4裂解炉的流动和传热情况有差异。由于炉管的非均匀传热,1／2裂解炉和1／4裂解炉炉管的热边界条件和管内裂解反应存在差异,从而导致了各主要产物收率不相同。3、考察了炉管进料量和炉膛燃料量等操作条件对炉内主要产物收率的影响。研究发现,进料量影响了炉管内的二次反应,进而对主要产物收率有重要影响。更多还原

【Abstract】 The ethylene cracking furnace was the core unit, and the thermal cracking process was one of the most important technologies of the ethylene industry. The main and complex process in a pyrolyzer include flow, combustion, pyrolysis reaction and heat transfer. China falls behind other countries of the cracking furnace in design and development. Only some foreign corporations hold the whole technique of cracking process. Thus, it is very significant to study details of transfer and reaction process in the cracking furnace.In this study, the numerical simulation of the flow and heat transfer in firebox and the reaction in tubes were carried out by establishing a three-dimensional model of a KTI GK-V cracking furnace. Majory research work was listed as follows:(1) A numerical model of the 1/4 furnace was developed by taking account of integrated phenomena that involves heat transfer, flow and pyrolysis reaction. The coupled impact of firebox and tubes was also studied. According to the research, non-uniform distribution of heat transfer existed in furnaces, thus resulted in a non-uniform distribution along the reactor tubes and a different product yield in each reactor tube. The mutual effects of heat transfer in the firebox and cracking reaction was responsible for the distribution of the heat boundary.(2) The coupled simulation was also carried out by establishing a three-dimensional model of the 1/2 furnace, which was close to the reality. The 1/2 furnace contains two sets of coils. According to the research, the temperature distribution was different between the 1/4 furnace and the 1/2 furnace due to the asymmetric structure. The coils which were near the wall got a poor heat transfer. The heat boundary condition and cracking reaction in 1/2 cracking furnace and 1/4 cracking furnace was different, due to the furnace tubes’non-uniform heat transfer, which caused different primary product yields.(3) The study of the feed quantity in the firebox and tubes on the yield of the main furnace were carried out. It was found that feed rate affected the secondary reaction in the pyrolysis furnace and the main product.更多还原