气相聚合流化床内聚合物结块的声波检测技术

Detection of Agglomeration in Gas-Phase Polymerization Fluidized-Bed by Using Sound Wave Technique

在420 mm的气相聚合流化床中进行了聚合物结块的检测实验。利用声波检测技术结合频谱分析,根据聚合物在结块的过程中碰撞流化床壁面产生不同声波信号的机理,提出了流化床内聚合物结块的判据,即团聚指数(I)。当I(0.2时,表明有结块产生;当I(-0.2时,则表明有粘壁结块产生,粘壁结块的尺寸在声波信号的低频能量处于极小值时达到最大。I是一个无因次量,具有一定的适用性。声波检测技术能有效、准确地预测和诊断流化床内聚合物的结块。

In fluidized-bed process for ethylene gas phase polymerization,agglomeration of polymer in fluidized-bed is a serious problem affecting the fluidizing state. Experiment of detecting agglomeration was carded out in gas phase polymerization fluidized-bed of 420 mm in diameter by using sound wave detection technique. The basic principle is that sound wave signals with different frequencies can emit when particles with different sizes impact wall of fluidized-bed. By analyzing the signals,a correlation and criterion for detecting agglomeration in fluidized-bed was presented. When agglomeration index（I） was more than 0.2, agglomeration would develop obviously. When I was less than - 0.2, agglomerates began to stick on wall of fluidized-bed. I is a dimensionless physical quantity and has broad applicability. Agglomeration in fluidized-bed can be quickly and precisely detected on-line by using the sound wave technique.