【作者】 赵爽；

【导师】 翟文杰；

【作者基本信息】 哈尔滨工业大学 ， 机械设计及理论， 2009， 硕士

【摘要】 增压锅炉作为舰船上常用的动力装置,具有高效率、高可靠性等优点。增压锅炉耐火砖墙的材料及结构对增压锅炉的性能有重大影响。由于炉墙各构件在结构上相互约束而自由热膨胀系数各不相同,温度变化将导致结构产生热应力。过大的热应力会造成炉墙组件的损坏,进而影响锅炉主体的破坏。因此开展对增压锅炉耐火砖墙的相关研究工作,对保证炉墙安全防止锅炉损坏具有重要意义,同时对于整个舰船的动力装置经济性和可靠性的提高也起到重要作用。本文以某实际舰用增压锅炉碳化硅耐火砖墙为研究对象,运用传热学及有限单元法原理,并结合所测定碳化硅耐火砖的热物理性能参数,建立了增压锅炉耐火砖墙结构的三维实体有限元模型;仿真模拟了增压锅炉在几种线性及非线性启动模式、不同升温速率以及不同散热降温条件下的瞬态温度场分布,获得了炉墙各构件在对应工况下温度场随时间的变化规律,并对不同工况下得到的炉墙典型构件的温度进行了对比分析。在增压锅炉耐火砖墙热应力分析方面,本文利用炉墙瞬态温度场分析结果进行了热应力计算,得出炉墙结构在各种工况下最大瞬态热应力随时间的变化规律。对增压锅炉从启动到达稳态过程中,炉墙的热变形和膨胀量进行了计算分析,并分析了碳化硅耐火砖的热物理性能参数对炉墙温度场和应力场的影响规律。研究结果为炉墙设计及碳化硅砖的研制提供了指导和参考规范。通过理论仿真计算得到如下主要结论:增压锅炉在启动过程中,升温速率越快,结构中产生的最大热应力也越大,炉墙外侧对流换热系数对不同工况启动过程下结构最大瞬态热应力值影响很小;降温过程中,炉墙内侧对流换热系数对结构最大瞬态热应力值影响显著。上述结合碳化硅砖性能测定的工程热分析结果对实际确定增压锅炉启动方式、升温速率和降温模式,以保证耐火砖墙乃至锅炉的安全有重要参考价值。更多还原

【Abstract】 As a general power device, supercharged boiler has the advantage of high efficiency and high reliability. Material and structure of supercharged boiler fireproof brick wall have a major impact on boiler performances. Temperatureshift can result in heat stress because brick wall components constrain each other but have different heat expansion coefficients. Overlarge heat stress may destroy the brick wall components and then the main body of boiler. For this reason, people had paid great attention to this and a lot of research work about supercharged boiler fireproof brick wall was carried, it is significant to ensure boiler wall in good condition and safety running for the work.This dissertation deals with the study of carborundum fireproof brick wall of supercharged boiler for vessels. Combined with thermophysics performances of carborundum fireproof brick wall gained by tests, 3D solid model and finite element model of fireproof brick wall are set up based on heat transfer theory and finite element principles. Transient temperature field distributions with different heating rates and temperature reduction conditions under several liner and unliner start modes are simulated, and the temporal change of brick wall components temperature field is shown. What’s more, temprature viration laws of some typical components are contrasted and analyzed.In the matter of heat stress analysis, heat stress is cuculated based on transient temperature field date, and the maximum transient heat stress which changes along with variation of time under different working conditions is gained. Heat deformation and swell increment during the boil runing process are caculated and the effecting law of carborundum fireproof brick wall thermophysics performance parameters on brick wall temperature field and heat stress field is analyzed, which provides guidance for brick wall design and carborundum brick study.From the therotical simulation, it can be concluded that, the higher the heating rates, the bigger the maximum heat stress, and the offside heat transfer coefficient have little impact on maximum transient heat stress while the inside heat transfer coefficient have remarkable impact on maximum transient heat stress. The thermoanalysis results combined with carborundum brick performance tests will do much help to determine boiler starting mode, heating rate and temperature reduction conditions in order to guarantee the safety of fireproof brick wall and even the boiler.更多还原