【作者】 贾燕子；

【导师】 卫宏远；

【作者基本信息】 天津大学 ， 化学工程， 2008， 硕士

【摘要】 裂解炉是乙烯生产装置的核心部分,燃烧器产生热量,是裂解炉的最重要组成部分。通过计算机技术建立数学模型,采用数值计算方法模拟裂解炉内所发生的各种过程,可以在少量的实验基础上获得大量的数据,为提高裂解技术提供必要的信息。本文按照从简单到复杂的规律开展研究,选择单个喷嘴为研究对象,以GAMBIT和FLUENT软件为平台,结合实际工业过程,选取适当的数学模型来描述计算域内所发生的燃料燃烧、烟气流动等过程和组分分布。首先采用GAMBIT软件建立计算域几何模型,并对计算域进行网格划分,建立数学模型,选择离散化方法。之后,在忽略辐射传热的前提下,应用FLUENT计算软件进行求解,分别采用ED模型、EDC模型、有限速率/涡耗散模型、非预混燃烧模型和组分PDF输运模型进行计算,对这五种燃烧模型的数值模拟结果进行对比分析,得出最适合于实际情况的燃烧模型为有限速率/涡耗散模型。选定燃烧模型后,本文考查了速度和计算域对燃烧结果的影响。采用有限速率/涡耗散燃烧模型,忽略辐射传热,考察了不同的燃料气进口速度(50m/s、100m/s、200m/s、300m/s及409m/s)对燃烧结果的影响;同时,把计算域沿X方向各向左右延伸0.5m,考查了计算域对燃烧结果的影响。最后,结合实际工业条件,选取两种比较适合本文工业条件的辐射模型,即:P-1辐射模型和DO辐射模型,考察辐射对燃烧结果的影响。对所得结果进行比较分析表明:虽然湍流反应速率仍为主要影响因素,但是加入辐射模型后,化学反应和辐射间的相互作用变得重要了,而且对于不同的辐射模型有不同的地位和作用。更多还原

【Abstract】 Ethylene cracking furnace is the core device for the ethylene production, while the burner is the most important component which used to generate heat. Large amounts of data can be acquired by simulating the various processes through the establishment of mathematical models, which provide necessary information to improve pyrolysis technology.In this paper, a single burner was chosen for the study using GAMBIT and FLUENT software as a platform; the appropriate mathematical model was selected according to the actual industrial process, to describe some phenomena happened in the furnace such as fuel gas movement and distribution of the species.First of all, the geometry model was established using GAMBIT software, the calculation domain was meshed, the mathematical model was established, and the discretization method was chosen. Then, the numerical results of five different combustion models, ED model, EDC model, the finite rate/eddy dissipation model, non-premixed combustion model and composition PDF transportation model, were compared ignoring radiation. It was concluded that the most suitable combustion model for the industrial situation is finite rate/eddy dissipation model.The influences of inlet velocity and calculation domain were investigated in this paper. The influence of the rate on the combustion was compared at the speed of 50m/s, 100m/s, 200m/s, 300m/s and 409m/s. At the same time, the calculation domain was extended about 0.5m along the X direction to examine the impact of the calculation domain on the combustion.Finally, two radiation models, P-1 radiation model and DO radiation model, were selected to determine the impact of radiation on the combustion. The results indicated that: although the turbulent reaction rate is significant for the turbulent combustion, chemical reaction and interaction between the radiations become important after the radiation model was added, different radiation models have different roles.更多还原