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富氧煤粉燃烧锅炉回收烟气在多级压缩和冷凝过程,其热物性参数的变化较为复杂,分析不同压力条件下烟气与冷却器对流受热面间的换热特性,对烟气冷却器的设计和运行优化有重要的意义。以某300 MW机组富氧煤粉燃烧锅炉烟气冷却器为研究对象,通过热力计算分析不同压力条件下烟气水蒸汽摩尔份额和烟气温度变化对对流受热面换热特性的影响,该过程充分考虑烟气的辐射放热计算。结果表明:当烟气的压力增大时,烟气的对流放热系数、辐射放热系数和凝结放热系数明显增大,总的放热系数增大,烟气冷却器对流受热面的换热能力增强;水蒸汽摩尔份额越少,烟气的对流放热系数、辐射放热系数和凝结放热系数越小,总的放热系数越小,烟气冷却器对流受热面的换热能力明显减弱;入口烟气温度升高使烟气的辐射放热系数增大。但是烟气的凝结放热系数明显减小,是使烟气总的放热系数减小的主要因素。
In the multi-stage compression and condensation process, the change of thermal physical parameters of the flue gas recovered from the oxygen-enriched coal combustion boiler is more complicated. The heat transfer characteristics of the flue gas cooler and the convective heating surface under different pressure conditions are analyzed. The design and operational optimization are of great importance. Based on the flue gas cooler of an oxygen-rich pulverized coal fired boiler of a 300 MW unit, the influence of the mole fraction of water vapor and flue gas temperature on the heat transfer characteristics of convective heating surface under different pressure conditions was analyzed by means of thermodynamic calculation. Take full account of the radiant heat radiation calculation. The results show that when the pressure of flue gas increases, the convection exothermic coefficient, radiation exothermic coefficient and condensation heat release coefficient of flue gas increase obviously, the total exothermic coefficient increases, and the flue gas cooler convection heat transfer surface exchange The smaller the mole fraction of water vapor, the smaller the convection exothermic coefficient, the radiative and the exothermic coefficient of flue gas, and the smaller the total exothermic coefficient, the heat transfer capacity of flue gas cooler convection heating surface Obviously weakened; the inlet flue gas temperature increases the radiation exothermic coefficient of flue gas increases. However, the condensation heat coefficient of flue gas obviously decreases, which is the main factor to reduce the total exothermic coefficient of flue gas.