300MW燃煤锅炉O2／CO2、烟气再循环燃烧的数值模拟

Numerical Simulation of O_2/CO_2 Recycled Flue Gas Combustion in a 300MW Boiler

以一台300MW四角切圆煤粉锅炉为研究对象,通过ICEM建立炉膛的三维结构框架及网格生成,在TASCFLOW中选择合适的炉内湍流流动、燃烧与传热的数学模型,进行煤粉在氧气体积比为29%时O2/CO2气氛下燃烧过程的数值模拟。研究发现:采用O2/CO2均匀混合送入炉膛时,煤粉的点火和燃烧较空气助燃时的状况有一定的延迟,火焰中心和炉膛内的高温区有明显扩大的趋势,火焰中心更接近炉膛中心,且沿炉膛高度有所上移;采用烟气再循环时,O2直接送入炉膛有利于煤粉的点火和燃烧,大大提高炉膛内的温度水平。

With a 300 MW tangentially corner-fired pulverized coal boiler serving as an object of study,the three-dimensional framework and mesh generation of a furnace was established by using software ICEM.A proper mathematical model for in-furnace turbulent flows,combustion and heat transfer was chosen in TASCFLOW to numerically simulate the pulverized-coal combustion process in O2/CO2 atmosphere at a volumetric ratio of oxygen assessed at 29%.It has been found that when the mixture of O2/CO2 was uniformly fed into the furnace,the pulverized-coal ignition and combustion will be delayed to a definite extent as compared with the case characterized by the presence of combustion-supporting air.The high-temperature zone in the flame center and furnace tends to be expanded conspicuously with the flame center being located more close to the furnace center and somehow moving upward along the furnace height.When the flue gas is recycled,oxygen is directly fed into the furnace,which would be favorable for the pulverized-coal ignition and combustion,greatly increasing the temperature in the furnace.