负压差立管气固流动的不稳定性实验分析

负压差立管内气固两相流具有流动的不稳定性，比较典型的是颗粒流量的不稳定性. 实验表明这种不稳定性主要有两种形式，一种是流量偏移，流量从一个值逐渐或突然转变为另一个值，这种现象一般发生在立管的入口或出口，是颗粒失流化架桥产生的；另一种是流量振荡，流量在一定的范围内发生波动变化，即低频脉动流动，这是颗粒逆压力梯度流动压缩气体造成的. 负压差立管气固流动的不稳定性对工艺过程的运行具有潜在的危害性.

Instability Analysis on Gas-Solid Two-phase Flow in the Standpipe under Negative Pressure Gradient

The paper presents an experimental study on the instability behaviors of gas-solid two-phase flow in a f150 mm11500 mm standpipe under negative pressure gradient. The gassolid two-phase flow in the standpipe is characteristic of the flowing against negative pressure and slip velocity upward, which made flow instability of the gassolid two-phase flow. There are two kinds of instability, one is the flowrate shift resulting from non-fluidization, the other is flowrate fluctuation resulting from compressed gas. Flowrate shift happened at the entrance or the exit of standpipe and the flowrate fluctuation occurred in any part of standpipe. The instability of gassolid two-phase flow in the standpipe has potential harm to the operation of circulating fluidized beds.