声场高温流化床流化特性

Flow Characteristics in a High Temperature Fluidized Bed with Sound Assistance

在内径50mm、高1000mm的声场高温鼓泡流化床中,研究Geldart A,B两类颗粒的流化特性,考察了床层温度、声波频率及声压级对流化床最小流化速度的影响.结果表明,引入声场后,颗粒的最小流化速度随温度升高而下降;固定温度及频率,最小流化速度随声压级增大而减小;固定声压级与温度,颗粒最小流化速度随声波频率增大先减小后增大,存在一个最佳频率范围.对床内压力波动信号进行分析,得出声场影响高温流化床流化质量的判据:当声压大于110dB、频率在100～200Hz范围内时压力波动偏差与最小流化速度值最小.

The flow characteristics in a bubbling fluidized bed of 50 mm i.d. and 1000 mm in height under sound excitation at high temperatures were investigated. With Geldart A, B group particles as fluidized materials, the effects of bed temperature, acoustic frequency and the sound pressure level （SpL） on the minimum fluidization velocity were examined in detail. It is demonstrated that the minimum fluidization velocity decreases with increasing temperature. At a given temperature and sound frequency, the velocity decreases with increasing SpL. At the same SpL and temperature, there always exists an optimal frequency range. As the sound frequency increases, the velocity decreases firstly and then increases. Based on the statistical analysis of pressure fluctuation signals, the criterion of influence on the fluidization quality at high-temperature fluidized bed was presented. The experimental results indicate that the pressure standard deviation and the minimum fluidization velocity decreases when the SpL is beyond 110 dB and acoustic frequency between 100-200 Hz.