中文摘要：

引言 气固循环流化床内的颗粒是沿着一个回路循环流动的，既有颗粒上行部分也有颗粒下行部分。通常上行部分是提升管，下行部分是立管和旋风分离器料腿。立管内气固两相流的一个重要特点是顺重力下行的颗粒速度大于气体速度，另一个特点是颗粒做顺重力逆压力梯度的下行运动，即颗粒从高处的低压端向低处的高压端流动。立管内的这种流动方式导致了立管内气固两相流的压力发生脉动。

英文摘要：

The characteristics of pressure fluctuation in a standpipe at negative pressure gradient were investigated based on measurement in the gas-solid two-phase circulating fluidized bed （CFB） . When the solid particles flowed downward from low pressure part to high pressure part in the standpipe, the particles compressed the gas entrained by them, which resulted in the instability of gas-solid two-phase flow. This instability was shown as pressure fluctuation, undulating particle velocity and uneven concentration. The range of pressure fluctuation was related to the negative pressure gradient in the standpipe.