火电机组锅炉炉膛负压优化策略研究

摘要

为研究火电机组锅炉炉膛负压控制技术,利用机理方法建立锅炉烟气压力数学模型,建模过程中采用分块建模方法,对锅炉内不同区域进行建模.由于快速甩负荷(FCB)过程属于火电机组运行的极端工况,炉膛压力控制如果对此工况适应即适应所有工况,所以采用FCB工况对所建模型进行仿真.仿真结果表明:随着燃料量的骤减,炉膛压力成先降后升的趋势,水平烟道和尾部烟道压力变化趋势与之类似;切磨时间间隔大,甩负荷过程中炉膛负压下降的最低点就越小.对于机组旁路容量大、机组负荷适应性强的机组,可适当增加甩负荷过程切磨时间间隔来减小炉膛压力的下降值,对于汽水系统热惯性小的机组,可以少切一台磨而选择减小给煤量的控制策略,上述方法可以减小炉膛压力波动,有利于炉内燃烧稳定.%The author built a model of boiler flue gas pressure based on mechanism analysis,besides,the author built models of different regions using block modeling method in the process of boiler modeling,for the study of thermal power boiler furnace pressure control technology.The process of FCB belongs to extreme conditions of thermal power units to run,therefore,the furnace pressure control which can adapt to this condition means will adapt to all conditions.The author carried out some simulation based on FCB conditions.The simulation results show that with the amount of fuel plummeting,furnace pressure presents the trend of increasing first and then decreasing,and the horizontal flue and flue at the rear have similar pressure.The smaller the cutting time interval is,the less the pressure drop in combustion chamber is in the process of FCB.For units that have high capacity for bypass and have strong adaptability to unit load,it may be appropriate to increase the FCB cutting time interval to reduce the decline in the value of the furnace pressure.For the unit that has small thermal inertia,we can choose to reduce the amount of coal rather than to reduce a mill,which can reduce the combustion chamber draft fluctuations and is conducive to the combustion stability.