基于风帽压力波动的横截面位置对循环流化床气固流动影响研究

RESEARCH ON EFFECTS OF CROSS-SECTION POSITION ON GAS-SOLID FLUIDIZATION OF CIRCULATING FLUIDIZED BEDS BASED ON PRESSURE FLUCTUATIONS IN WIND CAPS

提出利用采集、分析床内横截面方向不同位置风帽压力波动信号的方法,实现对循环流化床内横截面方向上气固两相流动状态的监测。借助冷态循环流化床实验台,在不同一次风表观气速条件下,同时测量床内横截面方向不同位置风帽的入口压力波动信号。采用标准差、小波分析和均匀指数等方法对风帽压力波动信号进行分析,得到信号的特征参数。然后基于横截面方向不同位置风帽的压力信号特征参数随一次风表观气速的变化规律,研究床内横截面位置对床内气固流态化特征的影响。结果发现,床内横截面方向不同位置风帽的压力信号特征参数能反映循环流化床一次风表观气速变化引起的床内横截面方向上气固流动状态的变化,表明所提方法具有可行性,并可为基于风帽压力波动特性的大截面循环流化床的状态监测建立理论基础。

A new method, measuring and analyzing pressure fluctuation signals of wind cap to monitor conditions of gas- solid flow along the horizontal direction in circulating fluidized bed, was proposed. The wind caps which were mounted with pressure taps were located at different cross-section positions of fluidized beds. The pressure fluctuation signals of wind caps were measured at different primary air velocities in a cold circulating fluidized bed. To obtain the corresponding characteristic parameters reflecting the effect of cross-section position on the gas-solid fluidization characteristics of circulating fluidized bed, the pressure fluctuation signals in different wind caps were analyzed with the methods of standard deviation, wavelet analysis and homogeneous index. Based on the characteristic parameters of pressure fluctuations in different wind caps, the effect of cross-section position on the gas-solid fluidization characteristics was analyzed. It is found that the variations of characteristic parameters of pressure fluctuations in wind caps which are located at different cross-section positions of fluidized bed are related with the variations of the gas-solid flow conditions along the horizontal direction in circulating fluidized bed, which are caused by the primary air velocity change. It is proved that the proposed method is practical and the research achievements can be used as a theoretical basis for the condition monitoring of circulating fluidized beds with large cross section based on pressure fluctuations in wind caps.