气固流化床分布板死区的声发射检测

Detection of distributor dead-zone in gas-solid fluidized bed by acoustic emission method

利用置于分布板下方的声发射传感器,采集气固流化床反应器中颗粒作用在分布板上产生的声信号.结合频谱分析并对照摄像法,发现由分布板下方采集到的声信号能量分布能够直观地反映分布板上死区分布的情况.当分布板上方某处存在死区时,该处声信号能量较其他点明显偏小.由此提出了基于声信号的流化床分布板死区检测的判据,即当分布板下方某处的声信号能量与该分布板所有测量点中的能量最大值的比值≤0.4时,流化床分布板存在死区.通过静床高分别为20和800 mm的气固流态化实验验证了判据的适用性,获得了一种快捷有效、实时在线的流化床分布板死区检测方法,可用于工业生产监控和操作优化.

Acoustic signals originated from particles impact on the distributor of the gas-solid fluidized bed were collected by the transducer located under the distributor. By analysing the signals with frequency spectrum analysis and comparing with experiment phenomenon, it was found that the acoustic energy can reflect the distribution of the defluidized area. As the energy was smaller when the area corresponding to the sample point exsited defluidization, a criterion to detect defluidization was presented. The criterion was that when the ratio of energy between the sample point and the largest value point was smaller than 0. 4,there was defluidization in the fluidized bed. Experiments were carried out in the gas-solid bed with the static bed height of 20 and 800 mm, and the result showed that this criterion was suitable for the online measurement of defluidization. Ultimately a {acile, sensitive, exact and on-line way to detect defluidization was acquired, which was applicable to the industry.