增压锅炉汽包瞬态温度场与应力场分析及在线监测

发布时间：2018-04-10 05:31

本文选题：增压锅炉　切入点：汽包　出处：《华北电力大学》2016年硕士论文

【摘要】：汽包是增压锅炉最大的高温厚壁承压部件,在锅炉启、停过程及变负荷运行时汽包的温度与应力变化剧烈,频繁的应力变化将引起疲劳寿命损耗。因此开发增压锅炉汽包在线监测系统,用于实时监测汽包温度与应力分布,对锅炉安全经济运行具有重要意义。如何在提高汽包温度场和应力场计算精度的同时又能保证较高的计算效率,是增压锅炉汽包在线监测系统研究的关键。针对增压锅炉汽包外壁受热的特点,提出了基于导热正反问题耦合解法的汽包瞬态温度场计算方法,通过编程求得整个汽包截面的温度场;然后在此基础上运用有限元方法,按照平面应变问题对汽包截面的瞬态理论应力进行求解分析。为了校验程序的计算精度,采用Ansys对某增压锅炉一次冷态启动过程汽包三维瞬态温度场与应力场进行了数值模拟,同时计算了二维瞬态理论应力。结合实验数据进行温度场对比,发现耦合解法对复杂边界条件具有较强的适应性。通过三维应力与理论应力的对比,计算相应的应力集中系数对二维有限元程序计算应力进行修正,能够快速精确的得到汽包的应力分布。根据应力模拟结果,基于雨流计数法,采用Miner线性累加损伤原理,计算汽包的寿命损耗,同时对汽包筒体与下降管连接处进行了应力强度校核。最终开发了一套增压锅炉汽包在线监测系统,指导锅炉安全经济运行。
[Abstract]:The steam drum is the largest high-temperature and thick-wall pressure-bearing part of the supercharged boiler. The temperature and stress of the drum vary sharply during the boiler start and stop and variable load operation. Frequent stress changes will cause fatigue life loss.Therefore, it is of great significance for boiler safety and economic operation to develop an on-line monitoring system for turbocharged boiler drum, which can be used to monitor the temperature and stress distribution of boiler drum in real time.How to improve the accuracy of the temperature field and stress field of the steam drum and at the same time ensure the high calculation efficiency is the key to the research of the on-line monitoring system of the turbocharged boiler drum.In view of the heating characteristics of the outer wall of the turbocharged boiler drum, a method of calculating the transient temperature field of the drum based on the coupling solution of the heat conduction forward and negative problems is proposed. The temperature field of the whole drum section is obtained by programming, and then the finite element method is used to calculate the temperature field of the whole drum section.According to the plane strain problem, the transient theoretical stress of the drum section is solved and analyzed.In order to verify the calculation accuracy of the program, the three-dimensional transient temperature field and stress field of the steam drum during the primary cold start-up of a turbocharged boiler were numerically simulated by using Ansys, and the two-dimensional transient theoretical stress was calculated at the same time.By comparing the temperature field with the experimental data, it is found that the coupled method has a strong adaptability to complex boundary conditions.By comparing the three-dimensional stress with the theoretical stress, the stress distribution of the drum can be obtained quickly and accurately by calculating the corresponding stress concentration factor to modify the two-dimensional finite element program.Based on the results of stress simulation and the method of rain flow counting, the life loss of the drum is calculated by using the principle of Miner linear cumulative damage, and the stress intensity of the connection between the cylinder and the descending tube is checked.Finally, a turbocharged boiler drum online monitoring system is developed to guide the safe and economical operation of the boiler.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK223.13

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