循环流化床锅炉一次风管道结构优化及流固耦合分析

发布时间：2018-02-14 09:05

本文关键词： 导流器一次风管道数值模拟静力学分析谐响应分析　出处：《内蒙古工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：锅炉机组在设计、建造过程中,考虑空间的有效利用,烟风系统存在很多弯管。由于弯管的结构特点,管内流体呈现复杂的流动特性,如速度分布不均、气固两相流在弯管附近形成分离区等。这些流动特性会造成流体总压和能量损失,会造成风量测量不准、管道振动等。首先,本文针对循环流化床锅炉热一次风管道的弯头多、直管段较短的特殊结构,提出在直管段入口位置加装栅格导流器。利用商业软件ANSYS workbench对栅格导流器结构进行了优化,包括确定导流器的栅格数量、栅格高度、栅格与管道轴线夹角和栅格板厚度等。优化结果为在导流器栅格数量为4×4、并分别与管道轴线成10°夹角、导流板高度为240mm、厚度为4mm时,均流效果较好、阻力损失较小。其次,将理论分析的优化结果在循环流化床锅炉上进行了实验验证。实验在三个工况下测试了安装导流器后热一次风管道内风量测量装置位置的风速分布。实验结果显示,加装导流器后,一次风管道内的风速分布较均匀,说明导流器起到了均流效果。同时,模拟结果与实验结果的吻合较好,说明模拟结果的准确性较高。最后,采用单向流固耦合的方法,利用ANSYS workbench软件,对加装导流器前后的热一次风管道进行了静力学、模态、谐响应、疲劳分析。静力学计算发现,加装导流器后,各工况下一次风管最大变形及最大应力比添加导流器前有小幅增加,说明导流器的添加对一次风管结构有影响,不过影响很小;模态分析发现,添加导流器后的一次风管道比添加导流器前的各级固有频率要小;谐响应分析发现,添加导流器后的一次风管道的共振频率比添加前小;疲劳分析发现,添加导流器前后疲劳分析结果基本相同,说明导流器添加不会对一次风管增加额外的疲劳损伤。通过本文的研究发现,在循环流化床锅炉一次风管道上加装栅格导流器对管道流场有明显的改善,对管道的振动有一定的影响,对管道寿命几乎没有影响。因此,在一次风弯管添加栅格导流器改善流场的方法是可行的。
[Abstract]:In the design and construction of boiler units, considering the effective use of space, there are many bends in the smoke and air system. Because of the structural characteristics of the bends, the fluid in the pipe presents complex flow characteristics, such as uneven velocity distribution. The gas-solid two-phase flow forms a separation zone near the bend tube. These flow characteristics will result in the loss of the total pressure and energy of the fluid, the inaccurate measurement of the air volume, the vibration of the pipeline, etc. Firstly, this paper aims at the number of bends in the circulating fluidized bed boiler heat primary air pipe. In this paper, a special structure with short straight pipe section is proposed, and a grid flow guide is installed at the entrance position of the straight pipe section. The structure of the grid diversion device is optimized by the commercial software ANSYS workbench, including determining the grid number and the grid height of the diversion device. The optimum results are as follows: when the number of grids is 4 脳 4, the angle is 10 掳with the pipe axis, the height of the guide plate is 240 mm, and the thickness is 4 mm, the effect of flow equalization is better and the loss of resistance is small. The optimized results of the theoretical analysis are experimentally verified on a circulating fluidized bed boiler. The wind velocity distribution of the air volume measuring device in the heat primary air pipe after the installation of the diffuser is tested under three operating conditions. The experimental results show that, The distribution of the wind velocity in the primary air duct is more uniform after the installation of the diversion device, which shows that the flow guide has the effect of flow equalization. At the same time, the simulation results are in good agreement with the experimental results, which shows that the accuracy of the simulation results is high. Finally, Using the method of unidirectional fluid-solid coupling and using ANSYS workbench software, the static, modal, harmonic response and fatigue analysis of the hot primary air pipe before and after the installation of the flow guide are carried out. The maximum deformation and maximum stress of primary air duct are slightly increased compared with those before adding diversion, which indicates that the addition of diversion has an effect on the structure of primary air duct, but the influence is very small. The modal analysis shows that the maximum deformation and maximum stress of primary air duct have little effect on the structure of primary air duct, and the modal analysis shows that, The resonance frequency of the primary air duct after adding the diversion is smaller than that before adding the diversion, and the harmonic response analysis shows that the resonance frequency of the primary air duct after adding the diversion is smaller than that before adding it, and the fatigue analysis shows that the resonance frequency of the primary air duct after adding the diversion is lower than that before adding it. The results of fatigue analysis before and after adding diversion device are basically the same, which indicates that the addition of diversion device does not increase the additional fatigue damage to primary air duct. The installation of grid guide on the primary air pipe of circulating fluidized bed boiler has obvious improvement on the flow field of the pipe, has certain influence on the vibration of the pipe, and has almost no effect on the life of the pipe. It is feasible to improve the flow field by adding a grid guide to the primary wind bend.
【学位授予单位】：内蒙古工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK229.66

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