流化床反应器富氧燃烧的数值模拟

发布时间：2018-11-28 21:09

【摘要】：近年来,为了缓解温室气体所带来的全球变暖,流化床富氧燃烧技术成为研究的焦点。本文仅是为一个完善的鼓泡流化床燃烧模拟计算的建立所进行的初步工作。本文采用欧拉-欧拉法描述气固两相间的相互作用,并以(the Kinetic Theory of Granular Flow)KTGF模型作为闭合方程,分别进行冷态和热态模拟。化学反应速率主要由阿伦尼乌斯方程描述,而异相反应则考虑扩散速率和固体比表面积的影响,引入效率因子。模拟结果与实验结果或者参考文献的数据进行对比,分析。在冷态模拟中,讨论了射流和湍流模型的影响。气泡的生成、上升、聚合和破碎过程均正常进行,并未受到二者影响,但是射流减小了床料层的压降和孔隙率,提高了气泡的均匀性,增强了局部区域气体的流速,减小了气泡的体积,同时降低了压力的波动幅度;湍流模型则增强了气固的紊乱,打乱了气泡的均匀分布,同时增加了床料层的压降。在热态模拟中,湍流模型增加了整个反应器的压降,同时提高了模拟与实验的吻合度,在模拟过程中应该启用湍流模型;而在化学反应速率方面,脱挥发分的反应速率设置偏大,同相反应反应速率设置偏小,应该予以调整。根据相关分析,对热态模拟进行优化,得到了相对理想的结果。
[Abstract]:In recent years, in order to mitigate the global warming caused by greenhouse gases, fluidized bed oxygen-enriched combustion technology has become the focus of research. This paper is only a preliminary work for the establishment of a complete simulation calculation of bubbling fluidized bed combustion. In this paper, the Euler-Euler method is used to describe the interaction between gas-solid phases, and the (the Kinetic Theory of Granular Flow) KTGF model is used as the closed equation to simulate the cold state and the hot state, respectively. The reaction rate is mainly described by Arrhenius equation, while the effect of diffusion rate and solid specific surface area is considered in heterogeneous reactions, and the efficiency factor is introduced. The simulation results are compared and analyzed with the experimental results or references. In the cold state simulation, the influence of jet and turbulence model is discussed. The formation, rise, polymerization and breakage of bubbles are normal, but the jet reduces the pressure drop and porosity of the bed layer, improves the uniformity of the bubble, and enhances the flow rate of the gas in the local area. The volume of bubble is reduced and the fluctuation of pressure is reduced. The turbulence model enhances the disorder of gas and solid, disrupts the uniform distribution of bubbles, and increases the pressure drop of bed layer. In the hot state simulation, the turbulence model increases the pressure drop of the whole reactor and improves the consistency between the simulation and the experiment, so the turbulence model should be used in the simulation process. On the other hand, the reaction rate of devolatilization is larger than that of in-phase reaction, and the setting of in-phase reaction rate should be adjusted. According to the correlation analysis, the thermal simulation is optimized and the relatively ideal results are obtained.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X701;X77

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