大容量超临界和超超临界压力锅炉炉膛传热公式

In-furnace Heat Transfer Formula for Large-capacity Supercritical and Ultra-supercritical Pressure Boilers

分析了以两个平行平面辐射换热公式作为蒸汽锅炉炉内火焰对四周水冷壁进行辐射传热计算方法仍是基本公式,推导出一维(横截面的径向)的辐射能在从炉膛中心向四周壁面传递时因火焰介质的吸收、自身辐射和散射作用造成的辐射强度的减弱,并在此基础上得出考虑了辐射能沿截面方向从炉膛中心向四周壁面减弱后的炉内辐射传热公式。以该公式和现有某些计算方法,对超临界和超超临界的大型煤粉电站锅炉在燃用含灰量不同的3种典型烟煤时分别进行了炉膛出口烟温的计算,和有关方法进行了比较,分析了这些方法存在的不足。

Analyzed were two parallel-plane radiative heat exchange formulae,which serve as the basic formulae for calculating the radiative heat transfer of in-furnace flames to the surrounding waterwalls in a steam boiler.Derived was the radiation intensity weakening of a one-dimensional (radial direction on a cross section) radiative energy caused by the following factors when the energy is transferred from the furnace center to surrounding wall surfaces.The factors are:absorption of flame media,self radiation and dispersion action.On this basis,a formula for radiative heat transfer in furnace was also deducted with due consideration of the weakening of radiative energy along the cross section direction from the furnace center to the surrounding wall surfaces.By using the derived formula and currently available calculation methods,the furnace outlet flue gas temperatures were calculated respectively when supercritical and ultra-supercritical large-sized pulverized coal utility boilers are burning three kinds of typical bituminous coal with different ash contents.The calculation method was compared with other relevant methods and the deficiencies of the methods in question were analyzed.