【作者】 梁倩；

【导师】 周怀春；

【作者基本信息】 华中科技大学 ， 热能工程， 2007， 硕士

【摘要】 大型电站锅炉过热器、再热器的超温爆管现象是锅炉运行中最常见的事故之一,严重影响到锅炉的安全经济运行。影响过热器、再热器爆管的主要因素是烟气侧的热负荷偏差、蒸汽侧的流量偏差和受热面的结构偏差。蒸汽在过热器和再热器中的流动状况将直接影响到过热器和再热器运行安全性。本文首先介绍了现有计算方法并指出了这些方法所存在的问题,然后具体分析了符合实际结构特征和流动特征的离散数学模型。本文对过热器汇流集箱和分配集箱分别建立了水动力学数学模型,讨论了冷态情况即集箱不受热时以及热态情况下集箱的静压分布和流量分配情况。在进行冷态情况计算时,主要讨论了集箱结构因素对汇流集箱和分配集箱的不同影响,得到了集箱内的静压分布和流量偏差系数。同时,本文对轴向引入引出的Z形集箱和U形集箱和径向引入引出的三通结构均进行了模拟。由于四角切圆燃烧方式本身的特点,使烟道内热负荷分布不均匀,另外由于集箱系统流量分配的不均匀,如果两者匹配不好就会造成较大的热偏差,将导致过热器、再热器的超温爆管,所以在热态情况计算时,讨论了几种常见的热负荷分布下汇流集箱和分配集箱的静压分布和流量分配情况。更多还原

【Abstract】 Tube bursting of superheater or reheater often happens in large capacity power plants,which severely threatens safety of boiler. The main factors for superheater and reheater’s leakage include heat flux deviation on the gas side,flow deviation on the steam side and heating surface’s structure deviation.The flow condition of steam in manifold systems will directly affect the operation security of superheater and reheater. Firstly this dissertation introduces the existing calculating methods and points out the unsatisfactory expressions. And then this dissertation completely analyzes the discrete model,which coincides with actual structure feature and the changing principle of the characteristic parameters of flow.This dissertation establishes hydrodynamic mathematics models for both distribution-headers and collection-headers and discusses static pressure distribution and flow deviation in the unheated condition and heated condition. In unheated condition,this dissertation studies the structure factors which have different effect on distribution-headers and collection-headers and calculates the static pressure distribution and the flow imbalance between panels. Meanwhile this dissertation simulates the Z-header and U-header and the manifolds whose inlet and outlet pipes use T-junction. Because of the inherent limitation of pulverized coal tangentially fired boiler,there is heat flux deviation in the flue. And there is also flow deviation in manifold systems. If they don’t coincide,it would result in superheater and reheater’s leakage. So in the heated condition,this dissertation discusses static pressure distribution and flow distribution characteristics in some common heat flux distributions. Meanwhile the flow distribution characteristics in different load are also studied.更多还原