声场流化床A类颗粒浓度分布研究

Investigation into Particle Concentration of Geldart Group A in an Acoustic Fluidized Bed

在内径140mm，高1600mm的鼓泡流化床中，以流化催化裂化（FCC）颗粒为流化介质，采用光导纤维探针测定不同轴／径向位置的颗粒浓度分布，考察了操作气速和外加声场对密相区颗粒浓度的影响。结果表明，鼓泡床密相区颗粒浓度沿轴向逐渐减小，沿径向呈抛物线分布。声场的引入可以降低颗粒起始流化速度；声压级越大，起始流化速度越小；固定声压频率在150Hz时颗粒起始流化速度最小。随着声压强度的增大，床层中心区和上部密相区颗粒浓度增大。固定声压级，频率在100～400Hz颗粒浓度较大，频率低于100Hz或高于400Hz时，声波的作用效果减弱。

The radial and axial profiles of the FCC particle concentrations were measured using an optical fiber probe in an acoustic fluidized bed （Ф140 mm× 1 600 mm）. The effects of sound wave frequency and sound pressure level on the particle concentration were explored. The results showed that the particle concentration tends to be lower with increasing the bed height, and the particle concentration was lower in fluidized bed center region than near the wall region. The incipient fluidization velocity was the minimum value when the frequency of sound waves was 150 Hz, and it decreased as the sound pressure level was increased at the same sound frequency. It was found that the particle concentration was increased at greater sound pressure level than 100 dB and the sound frequency ranging from 100 Hz to 400 Hz. However, the effect of acoustic field on the particle concentration was weakened and even disappeared when the sound frequency was lower than 100 Hz or greater than 400 Hz.