Frequency analysis of acoustic emission and applicati on in gas-solid fluidized bed
Frequency analysis of acoustic emission and applicati on in gas-solid fluidized bed
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发表时间：
2005
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通讯作者：
Huang Xiaoping
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作者：
Huang Xiaoping
提出了气固流化床信号主频测量模型，表达了主频与颗粒尺寸、温度、杨氏模量和密度的定量关系。声发射（AE）测量具有完全非侵入性、不受背景噪声影响、不对人体造成伤害等优点，本文采用快速傅立叶变换（FFT）分析仪进行了基于AE测量的实验研究。结果表明，随着颗粒尺寸、温度、杨氏模量和密度的增加，信号的主频降低。在流化床中进行了i. d.对150 mm厚的聚乙烯样品进行了计算，结果表明，在主频（LLDPE、HDPE和双峰聚乙烯）方面，计算值与实验值吻合较好，平均误差均小于8.3%。探讨了通过调整弹性组分的比例来放大工艺流程的可行性。将该模型应用于LLDPE、HDPE和双峰聚乙烯工业流化床，计算值与实验值的平均误差分别为3.9%、8.2%和8.8%。根据主频率的急剧下降和振幅的急剧增加的判据，可以发展一种新的方法来判断流化是否稳定运行，并在未来取代γ射线测量。
A model of signal main-frequency measurement was pres en ted for the gas-solid fluidized bed to represent the quantitative relation of m ain-frequency and particle size,temperature, Young’s modulus and density . The acoustic emission(AE) measurement was completely non-intrusive and not affected by the background noises, and caused to human harm.The experiment based on AE measurement was performed by using a fast Fourier transform (FFT) analyze r in this study. It was found the signals main-frequency decreased with the inc reasing particle size, temperature, Young’s modulus and density. The expe riment in the fluidized bed with i.d. of 150 mm showed that satisfactory agree ment was obtained between calculated and experimental data with respect of the m ain-frequency (LLDPE, HDPE and bimodal polyethylene), and the average errors we re all less than 8.3%. The scale-up feasibility of the technical process was d iscussed by adjusting the elastic partameter. When the AE signals main-frequenc y model was applied to the industrial fluidized bed of LLDPE, HDPE, bimodal poly ethylene, the mean errors between calculated and experimental data were 3.9%,8 .2% and 8.8% respectively. By the criterion of the sharp decrease of main-fre quency and the sharp increase of amplitude, a novel approach could be developed to judge whether the fluidization runs stably, and it could replace the γ-ray measurement in the future.