静床高对大截面流化床锅炉床压横向波动影响的模型

Modelling research on effects of static bed height on lateral bed pressure fluctuations in large cross-section circulating fluidized bed boilers

单炉膛、单布风板的大型循环流化床(CFB)锅炉,由于炉膛截面宽,在运行过程中时而存在床层两侧压力大幅度、交替波动的床压横向波动问题,严重影响了锅炉的安全经济运行。为了从理论上解释大截面CFB锅炉床压横向波动的机制,建立了CFB锅炉床压横向波动的非线性浅床长波驻波模型以及密相区气固流态化数学模型,并利用2台300 MW亚临界CFB锅炉的结构尺寸、运行参数及床压测试数据对模型参数进行确定。模型耦合计算的结果表明:床压横向波动幅度、周期的模拟值与实炉测试值很好地吻合;静床高对床压横向波动时炉内床压分布、床压波动幅度和周期、活性区和非活性区床高、非活性区空隙率分布等均有一定程度的影响。

Because of the wide cross section,the large-scale circulating fluidized bed（ CFB） boilers with one combustion chamber and one distributer were sometimes operated accompanying with severe lateral bed pressure fluctuations,which posed a serious threat to the stability and safety of the boilers. In order to interpret the mechanisms of lateral bed pressure fluctuations in large-scale CFB boilers in theory,a nonlinear long standing wave model for a shallow bed of bed pressure fluctuations and mathematical models of the fluidization in dense-phase were built. The structure sizes,operational parameters and bed pressure measured data of two 300 MW subcritical CFB boilers were used to determine the model parameters. The coupling calculation results of models show that the simulation results of the amplitudes and periods of pressure fluctuations are presented in good agreement with the corresponding measured data. Bed pressure distribution along the bed width,the amplitudes and periods of lateral bed pressure fluctuations,the heights of the active section and inactive section,and voidage distribution in inactive section,all have a certain relationship with the static bed height.