【作者】 闫晓沛；

【导师】 罗自学； 周怀春；

【作者基本信息】 华中科技大学 ， 热能工程， 2011， 硕士

【摘要】 锅炉是火电站的重要部件之一,锅炉蒸发系统包含了燃烧和工质蒸发过程,因此对锅炉蒸发系统研究有益于电站锅炉的安全运行。本文基于三维温度场可视化监测技术,开展了炉内燃烧放热过程和锅内吸热蒸发过程的建模,以姚孟发电有限责任公司某台300MW亚临界双炉膛直流锅炉为对象,仿真研究了蒸发系统物理参数的分布特性及变化规律,并进行了模型验证。提出假想面的处理方法简化双炉膛的模型,根据三维燃烧监测系统得到炉内三维温度场分布,可以得到假想面的二维热流密度分布和壁温分布,从而解决了因采用经验值而导致计算不合理的情况。蒸发系统分布参数模型以实时监测得到的炉内三维温度分布和颗粒相黑度为依据,计算蒸发系统水冷壁各面墙的二维热流密度分布;上升管内工质汽化过程基于质量守恒、能量守恒和动量守恒定律,金属壁温采用二维稳态导热方程计算。模型计算得到的工质换热量以及金属壁温分布参数能够准确地跟踪锅炉运行的工况,避免了传统模型中通过热电偶测得有限壁温数据或采用分段计算加经验系数修正来计算壁面吸热量所引起的模型误差。利用现场采集数据验证了模型的合理性与正确性。通过对锅炉改造前后的水冷壁壁面热流密度分布、壁面温度分布以及质量含汽率分布等的对比分析,为亚临界双炉膛直流锅炉实际运行提供了有益的指导,且模型具有很好的扩展性,为水动力特性的实验研究提供了一种新方法。更多还原

【Abstract】 Boiler is an important part of the power plant. The studying on the evaporation system of the boiler is crucial for safe operation, which related to combustion behavior in furnace and evaporation of working substance. In this paper, a distributed parameter model for the evaporation system which fused the combustion process and the heat absorption was obtained based on 3-D temperature distribution by flame image processing technique and proved in a 300MW twin-furnace subcritical once-through boiler of Yaomeng Power Plant. The transient distributions and variations of the parameters were researched by the mathematical model.The imaginary wall surface was put forward to simplify the twin-furnace problem based on 3-D temperature field reconstruction. Then, the 2-D radiation flux and temperature of the imaginary wall surface can be obtained which avoiding the unreasonable results by empirical value. The model of non-uniformly distribution in two-dimensional surfaces of water-wall tubes was established by using the real-time 3-D temperature distribution and the emissivity of the particle phase inside its furnace. The mathematical model for predicting the dynamics in risers was put forward based on the mass, energy and momentum conservation equations. The real-time heat absorbed and temperature of mental wall in different operating conditions would be provided, avoiding the error of rough accuracy heat computation which would be determined from the temperature between some certain points on the rear of wall or calculated by the method of empirical auxiliary value.The simulation results were proved to be reasonable and correct by comparing with the operating status of power plant. The distributions of the parameters before/after reformation, such as heat flux, metal temperature and steam quality and so on, were analyzed relatively, which formed an important basis to optimize the actual motion of the twin-furnace subcritical once-through boiler. The model has great flexibility and extensibility which supplied a new process to research the hydrodynamic force characteristic.更多还原