采用双混合分数/概率密度函数方法模拟混煤燃烧

Simulation of Coal Blended Combustion With the Two-mixture-fraction/PDF Method

混煤燃烧存在复杂的相互影响,将混煤当成单一煤种并采用单混合分数/概率密度函数(probability density function,PDF)方法计算,意味着忽略了煤种之间的影响,结果会产生很大偏差。而双混合分数/PDF方法可以分别定义各单煤性质并跟踪各单煤的燃烧过程,能够体现煤种之间燃烧特性的影响。利用单、双混合分数/PDF方法对同1台300 MW四角切圆锅炉进行模拟研究,并与实测数据进行对比,结果表明:双混合分数/PDF方法模拟的结果更符合混煤在炉内实际的燃烧情况。同时采用双混合分数/PDF方法模拟某一混煤燃烧过程,得到燃烧煤粉锅炉的流动,温度和烟气分布等特性。

Coals after blended can influence each other much in the combustion process. So if assuming blended coals as a single coal and using the single-mixture-fraction/ probability density function （PDF） method to compute the combustion of blended coals, the influences between different kinds of coals could be ignored and the results were far from the measurement data. In order to demonstrate the interaction between different coals in the combustion process, it is necessary to adopt the two-mixture-fraction/PDF method to define the property of each kind of blended coals and trace the combustion process of every single coal respectively. A 300 MW tangentially fired boiler furnace was studied by the single-mixture-fraction/PDF and the two-mixture-fraction/PDF approach respectively, then the results were compared with the measured data. The comparison shows that the results computed by the two-mixture-fraction/PDF calculation approach more in conformity with the real combustion of blended coals. Meanwhile the combustion of blended coals has been simulated by the two-mixture-fraction/PDF calculation approach and the flow of pulverized coal combustion, temperature and hot gas distribution and other characteristics have been obtained.